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gcc-reflection/gcc/tree-ssa-phiopt.cc
Jakub Jelinek 254a858ae7 Update copyright years.
2026-01-02 09:56:11 +01:00

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/* Optimization of PHI nodes by converting them into straightline code.
Copyright (C) 2004-2026 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "insn-codes.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "cfghooks.h"
#include "tree-pass.h"
#include "ssa.h"
#include "tree-ssa.h"
#include "optabs-tree.h"
#include "insn-config.h"
#include "gimple-pretty-print.h"
#include "fold-const.h"
#include "stor-layout.h"
#include "cfganal.h"
#include "gimplify.h"
#include "gimple-iterator.h"
#include "gimplify-me.h"
#include "tree-cfg.h"
#include "tree-dfa.h"
#include "domwalk.h"
#include "cfgloop.h"
#include "tree-data-ref.h"
#include "tree-scalar-evolution.h"
#include "tree-inline.h"
#include "case-cfn-macros.h"
#include "tree-eh.h"
#include "gimple-fold.h"
#include "internal-fn.h"
#include "gimple-range.h"
#include "gimple-match.h"
#include "dbgcnt.h"
#include "tree-ssa-propagate.h"
#include "tree-ssa-dce.h"
#include "tree-ssa-loop-niter.h"
/* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
static gphi *
single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1)
{
gimple_stmt_iterator i;
gphi *phi = NULL;
for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
{
gphi *p = as_a <gphi *> (gsi_stmt (i));
/* If the PHI arguments are equal then we can skip this PHI. */
if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p, e0->dest_idx),
gimple_phi_arg_def (p, e1->dest_idx)))
continue;
/* Punt on virtual phis with different arguments from the edges. */
if (virtual_operand_p (gimple_phi_result (p)))
return NULL;
/* If we already have a PHI that has the two edge arguments are
different, then return it is not a singleton for these PHIs. */
if (phi)
return NULL;
phi = p;
}
return phi;
}
/* Replace PHI node element whose edge is E in block BB with variable NEW.
Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
is known to have two edges, one of which must reach BB). */
static void
replace_phi_edge_with_variable (basic_block cond_block,
edge e, gphi *phi, tree new_tree,
bitmap dce_ssa_names = nullptr)
{
basic_block bb = gimple_bb (phi);
gimple_stmt_iterator gsi;
tree phi_result = gimple_phi_result (phi);
bool deleteboth = false;
/* Duplicate range info if they are the only things setting the target PHI.
This is needed as later on, the new_tree will be replacing
The assignement of the PHI.
For an example:
bb1:
_4 = min<a_1, 255>
goto bb2
# RANGE [-INF, 255]
a_3 = PHI<_4(1)>
bb3:
use(a_3)
And _4 gets propagated into the use of a_3 and losing the range info.
This can't be done for more than 2 incoming edges as the propagation
won't happen.
The new_tree needs to be defined in the same basic block as the conditional. */
if (TREE_CODE (new_tree) == SSA_NAME
&& EDGE_COUNT (gimple_bb (phi)->preds) == 2
&& INTEGRAL_TYPE_P (TREE_TYPE (phi_result))
&& !SSA_NAME_RANGE_INFO (new_tree)
&& SSA_NAME_RANGE_INFO (phi_result)
&& gimple_bb (SSA_NAME_DEF_STMT (new_tree)) == cond_block
&& dbg_cnt (phiopt_edge_range))
duplicate_ssa_name_range_info (new_tree, phi_result);
/* Change the PHI argument to new. */
SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
/* Remove the empty basic block. */
edge edge_to_remove = NULL, keep_edge = NULL;
if (EDGE_SUCC (cond_block, 0)->dest == bb)
{
edge_to_remove = EDGE_SUCC (cond_block, 1);
keep_edge = EDGE_SUCC (cond_block, 0);
}
else if (EDGE_SUCC (cond_block, 1)->dest == bb)
{
edge_to_remove = EDGE_SUCC (cond_block, 0);
keep_edge = EDGE_SUCC (cond_block, 1);
}
else if ((keep_edge = find_edge (cond_block, e->src)))
{
basic_block bb1 = EDGE_SUCC (cond_block, 0)->dest;
basic_block bb2 = EDGE_SUCC (cond_block, 1)->dest;
if (single_pred_p (bb1) && single_pred_p (bb2)
&& single_succ_p (bb1) && single_succ_p (bb2)
&& empty_block_p (bb1) && empty_block_p (bb2))
deleteboth = true;
}
else
gcc_unreachable ();
/* If we are removing the cond on a loop exit,
reset number of iteration information of the loop. */
if (loop_exits_from_bb_p (cond_block->loop_father, cond_block))
{
auto loop = cond_block->loop_father;
free_numbers_of_iterations_estimates (loop);
loop->any_upper_bound = false;
loop->any_likely_upper_bound = false;
}
if (edge_to_remove && EDGE_COUNT (edge_to_remove->dest->preds) == 1)
{
e->flags |= EDGE_FALLTHRU;
e->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
e->probability = profile_probability::always ();
delete_basic_block (edge_to_remove->dest);
/* Eliminate the COND_EXPR at the end of COND_BLOCK. */
gsi = gsi_last_bb (cond_block);
gsi_remove (&gsi, true);
}
else if (deleteboth)
{
basic_block bb1 = EDGE_SUCC (cond_block, 0)->dest;
basic_block bb2 = EDGE_SUCC (cond_block, 1)->dest;
edge newedge = redirect_edge_and_branch (keep_edge, bb);
/* The new edge should be the same. */
gcc_assert (newedge == keep_edge);
keep_edge->flags |= EDGE_FALLTHRU;
keep_edge->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
keep_edge->probability = profile_probability::always ();
/* Copy the edge's phi entry from the old one. */
copy_phi_arg_into_existing_phi (e, keep_edge);
/* Delete the old 2 empty basic blocks */
delete_basic_block (bb1);
delete_basic_block (bb2);
/* Eliminate the COND_EXPR at the end of COND_BLOCK. */
gsi = gsi_last_bb (cond_block);
gsi_remove (&gsi, true);
}
else
{
/* If there are other edges into the middle block make
CFG cleanup deal with the edge removal to avoid
updating dominators here in a non-trivial way. */
gcond *cond = as_a <gcond *> (*gsi_last_bb (cond_block));
if (keep_edge->flags & EDGE_FALSE_VALUE)
gimple_cond_make_false (cond);
else if (keep_edge->flags & EDGE_TRUE_VALUE)
gimple_cond_make_true (cond);
}
if (dce_ssa_names)
simple_dce_from_worklist (dce_ssa_names);
statistics_counter_event (cfun, "Replace PHI with variable", 1);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file,
"COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
cond_block->index,
bb->index);
}
/* Returns true if the ARG used from DEF_STMT is profitable to move
to a PHI node of the basic block MERGE where the new statement
will be located. */
static bool
is_factor_profitable (gimple *def_stmt, basic_block merge, tree arg)
{
/* The defining statement should be conditional. */
if (dominated_by_p (CDI_DOMINATORS, merge,
gimple_bb (def_stmt)))
return false;
/* If the arg is invariant, then there is
no extending of the live range. */
if (is_gimple_min_invariant (arg))
return true;
/* Otherwise, the arg needs to be a ssa name. */
if (TREE_CODE (arg) != SSA_NAME)
return false;
/* We should not increase the live range of arg
across too many statements or calls. */
gimple_stmt_iterator gsi = gsi_for_stmt (def_stmt);
gsi_next_nondebug (&gsi);
/* Skip past nops and predicates. */
while (!gsi_end_p (gsi)
&& (gimple_code (gsi_stmt (gsi)) == GIMPLE_NOP
|| gimple_code (gsi_stmt (gsi)) == GIMPLE_PREDICT))
gsi_next_nondebug (&gsi);
/* If the defining statement is at the end of the bb, then it is
always profitable to be to move. */
if (gsi_end_p (gsi))
return true;
/* Check if the uses of arg is dominated by merge block, this is a quick and
rough estimate if arg is still alive at the merge bb. */
/* FIXME: extend to a more complete live range detection. */
use_operand_p use_p;
imm_use_iterator iter;
FOR_EACH_IMM_USE_FAST (use_p, iter, arg)
{
gimple *use_stmt = USE_STMT (use_p);
basic_block use_bb = gimple_bb (use_stmt);
if (dominated_by_p (CDI_DOMINATORS, merge, use_bb))
return true;
}
/* If there are a few (non-call/asm) statements between
the old defining statement and end of the bb, then
the live range of new arg does not increase enough. */
int max_statements = param_phiopt_factor_max_stmts_live;
while (!gsi_end_p (gsi))
{
gimple *stmt = gsi_stmt (gsi);
auto gcode = gimple_code (stmt);
/* Skip over NOPs and predicts. */
if (gcode == GIMPLE_NOP
|| gcode == GIMPLE_PREDICT)
{
gsi_next_nondebug (&gsi);
continue;
}
/* Non-assigns will extend the live range too much. */
if (gcode != GIMPLE_ASSIGN)
return false;
max_statements --;
if (max_statements == 0)
return false;
gsi_next_nondebug (&gsi);
}
return true;
}
/* PR66726: Factor operations out of COND_EXPR. If the arguments of the PHI
stmt are Unary operator, factor out the operation and perform the operation
to the result of PHI stmt. COND_STMT is the controlling predicate.
Return true if the operation was factored out; false otherwise. */
static bool
factor_out_conditional_operation (edge e0, edge e1, basic_block merge,
gphi *phi, gimple *cond_stmt)
{
gimple *arg0_def_stmt = NULL, *arg1_def_stmt = NULL;
tree temp, result;
gphi *newphi;
gimple_stmt_iterator gsi, gsi_for_def;
location_t locus = gimple_location (phi);
gimple_match_op arg0_op, arg1_op;
/* We should only get here if the phi had two arguments. */
gcc_assert (gimple_phi_num_args (phi) == 2);
/* Virtual operands are never handled. */
if (virtual_operand_p (gimple_phi_result (phi)))
return false;
tree arg0 = gimple_phi_arg_def (phi, e0->dest_idx);
tree arg1 = gimple_phi_arg_def (phi, e1->dest_idx);
location_t narg0_loc = gimple_location (phi);
location_t narg1_loc = gimple_location (phi);
if (gimple_phi_arg_location (phi, e0->dest_idx) != UNKNOWN_LOCATION)
narg0_loc = gimple_phi_arg_location (phi, e0->dest_idx);
if (gimple_phi_arg_location (phi, e1->dest_idx) != UNKNOWN_LOCATION)
narg1_loc = gimple_phi_arg_location (phi, e1->dest_idx);
gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE);
/* Arugments that are the same don't have anything to be
done to them. */
if (operand_equal_for_phi_arg_p (arg0, arg1))
return false;
/* First canonicalize to simplify tests. */
if (TREE_CODE (arg0) != SSA_NAME)
{
std::swap (arg0, arg1);
std::swap (e0, e1);
}
if (TREE_CODE (arg0) != SSA_NAME
|| (TREE_CODE (arg1) != SSA_NAME
&& TREE_CODE (arg1) != INTEGER_CST))
return false;
/* Check if arg0 is an SSA_NAME and the stmt which defines arg0 is
an unary operation. */
arg0_def_stmt = SSA_NAME_DEF_STMT (arg0);
if (!gimple_extract_op (arg0_def_stmt, &arg0_op))
return false;
/* Check to make sure none of the operands are in abnormal phis. */
if (arg0_op.operands_occurs_in_abnormal_phi ())
return false;
/* Currently just support one operand expressions. */
if (arg0_op.num_ops != 1)
return false;
tree new_arg0 = arg0_op.ops[0];
tree new_arg1;
/* If arg0 have > 1 use, then this transformation actually increases
the number of expressions evaluated at runtime. */
if (!has_single_use (arg0))
return false;
if (!is_factor_profitable (arg0_def_stmt, merge, new_arg0))
return false;
if (gimple_has_location (arg0_def_stmt))
narg0_loc = gimple_location (arg0_def_stmt);
if (TREE_CODE (arg1) == SSA_NAME)
{
/* Check if arg1 is an SSA_NAME. */
arg1_def_stmt = SSA_NAME_DEF_STMT (arg1);
if (!gimple_extract_op (arg1_def_stmt, &arg1_op))
return false;
if (arg1_op.code != arg0_op.code)
return false;
if (arg1_op.num_ops != arg0_op.num_ops)
return false;
if (arg1_op.operands_occurs_in_abnormal_phi ())
return false;
/* If arg1 have > 1 use, then this transformation actually increases
the number of expressions evaluated at runtime. */
if (!has_single_use (arg1))
return false;
new_arg1 = arg1_op.ops[0];
if (!is_factor_profitable (arg1_def_stmt, merge, new_arg1))
return false;
if (gimple_has_location (arg1_def_stmt))
narg1_loc = gimple_location (arg1_def_stmt);
/* Chose the location for the new statement if the phi location is unknown. */
if (locus == UNKNOWN_LOCATION)
{
if (narg0_loc == UNKNOWN_LOCATION
&& narg1_loc != UNKNOWN_LOCATION)
locus = narg1_loc;
else if (narg0_loc != UNKNOWN_LOCATION
&& narg1_loc == UNKNOWN_LOCATION)
locus = narg0_loc;
}
}
else
{
/* For constants only handle if the phi was the only one. */
if (single_non_singleton_phi_for_edges (phi_nodes (merge), e0, e1) == NULL)
return false;
/* TODO: handle more than just casts here. */
if (!gimple_assign_cast_p (arg0_def_stmt))
return false;
/* arg0_def_stmt should be conditional. */
if (dominated_by_p (CDI_DOMINATORS, gimple_bb (phi), gimple_bb (arg0_def_stmt)))
return false;
/* If arg1 is an INTEGER_CST, fold it to new type if it fits, or else
if the bits will not be modified during the conversion, except for
boolean types whose precision is not 1 (see int_fits_type_p). */
if (!INTEGRAL_TYPE_P (TREE_TYPE (new_arg0))
|| !(int_fits_type_p (arg1, TREE_TYPE (new_arg0))
|| (TYPE_PRECISION (TREE_TYPE (new_arg0))
== TYPE_PRECISION (TREE_TYPE (arg1))
&& (TREE_CODE (TREE_TYPE (new_arg0)) != BOOLEAN_TYPE
|| TYPE_PRECISION (TREE_TYPE (new_arg0)) == 1))))
return false;
/* For the INTEGER_CST case, we are just moving the
conversion from one place to another, which can often
hurt as the conversion moves further away from the
statement that computes the value. So, perform this
only if new_arg0 is an operand of COND_STMT, or
if arg0_def_stmt is the only non-debug stmt in
its basic block, because then it is possible this
could enable further optimizations (minmax replacement
etc.). See PR71016.
Note no-op conversions don't have this issue as
it will not generate any zero/sign extend in that case. */
if ((TYPE_PRECISION (TREE_TYPE (new_arg0))
!= TYPE_PRECISION (TREE_TYPE (arg1)))
&& new_arg0 != gimple_cond_lhs (cond_stmt)
&& new_arg0 != gimple_cond_rhs (cond_stmt)
&& gimple_bb (arg0_def_stmt) == e0->src)
{
gsi = gsi_for_stmt (arg0_def_stmt);
gsi_prev_nondebug (&gsi);
/* Ignore nops, predicates and labels. */
while (!gsi_end_p (gsi)
&& (gimple_code (gsi_stmt (gsi)) == GIMPLE_NOP
|| gimple_code (gsi_stmt (gsi)) == GIMPLE_PREDICT
|| gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL))
gsi_prev_nondebug (&gsi);
if (!gsi_end_p (gsi))
{
gimple *stmt = gsi_stmt (gsi);
if (gassign *assign = dyn_cast <gassign *> (stmt))
{
tree lhs = gimple_assign_lhs (assign);
tree lhst = TREE_TYPE (lhs);
enum tree_code ass_code
= gimple_assign_rhs_code (assign);
if (ass_code != MAX_EXPR && ass_code != MIN_EXPR
/* Conversions from boolean like types is ok
as `a?1:b` and `a?0:b` will always simplify
to `a & b` or `a | b`.
See PR 116890. */
&& !(INTEGRAL_TYPE_P (lhst)
&& TYPE_UNSIGNED (lhst)
&& TYPE_PRECISION (lhst) == 1))
return false;
if (lhs != gimple_assign_rhs1 (arg0_def_stmt))
return false;
gsi_prev_nondebug (&gsi);
if (!gsi_end_p (gsi))
return false;
}
else
return false;
}
}
new_arg1 = fold_convert (TREE_TYPE (new_arg0), arg1);
/* Drop the overlow that fold_convert might add. */
if (TREE_OVERFLOW (new_arg1))
new_arg1 = drop_tree_overflow (new_arg1);
/* The locus of the new statement is arg0 defining statement. */
if (gimple_has_location (arg0_def_stmt))
locus = gimple_location (arg0_def_stmt);
}
/* If types of new_arg0 and new_arg1 are different bailout. */
if (!types_compatible_p (TREE_TYPE (new_arg0), TREE_TYPE (new_arg1)))
return false;
/* Create a new PHI stmt. */
result = gimple_phi_result (phi);
temp = make_ssa_name (TREE_TYPE (new_arg0), NULL);
gimple_match_op new_op = arg0_op;
/* Create the operation stmt if possible and insert it. */
new_op.ops[0] = temp;
gimple_seq seq = NULL;
result = maybe_push_res_to_seq (&new_op, &seq, result);
/* If we can't create the new statement, release the temp name
and return back. */
if (!result)
{
release_ssa_name (temp);
return false;
}
if (locus != UNKNOWN_LOCATION)
annotate_all_with_location (seq, locus);
gsi = gsi_after_labels (gimple_bb (phi));
gsi_insert_seq_before (&gsi, seq, GSI_CONTINUE_LINKING);
newphi = create_phi_node (temp, gimple_bb (phi));
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "PHI ");
print_generic_expr (dump_file, gimple_phi_result (phi));
fprintf (dump_file,
" changed to factor operation out from COND_EXPR.\n");
fprintf (dump_file, "New stmt with OPERATION that defines ");
print_generic_expr (dump_file, result);
fprintf (dump_file, ".\n");
}
/* Remove the old operation(s) that has single use. */
gsi_for_def = gsi_for_stmt (arg0_def_stmt);
gsi_remove (&gsi_for_def, true);
release_defs (arg0_def_stmt);
if (arg1_def_stmt)
{
gsi_for_def = gsi_for_stmt (arg1_def_stmt);
gsi_remove (&gsi_for_def, true);
release_defs (arg1_def_stmt);
}
add_phi_arg (newphi, new_arg0, e0, narg0_loc);
add_phi_arg (newphi, new_arg1, e1, narg1_loc);
/* Remove the original PHI stmt. */
gsi = gsi_for_stmt (phi);
gsi_remove (&gsi, true);
statistics_counter_event (cfun, "factored out operation", 1);
return true;
}
/* Return TRUE if SEQ/OP pair should be allowed during early phiopt.
Currently this is to allow MIN/MAX and ABS/NEGATE and constants. */
static bool
phiopt_early_allow (gimple_seq &seq, gimple_match_op &op)
{
/* Don't allow functions. */
if (!op.code.is_tree_code ())
return false;
tree_code code = (tree_code)op.code;
/* For non-empty sequence, only allow one statement
a MIN/MAX and an original MIN/MAX. */
if (!gimple_seq_empty_p (seq))
{
if (code == MIN_EXPR || code == MAX_EXPR)
{
if (!gimple_seq_singleton_p (seq))
return false;
gimple *stmt = gimple_seq_first_stmt (seq);
/* Only allow assignments. */
if (!is_gimple_assign (stmt))
return false;
code = gimple_assign_rhs_code (stmt);
return code == MIN_EXPR || code == MAX_EXPR;
}
return false;
}
switch (code)
{
case MIN_EXPR:
case MAX_EXPR:
case ABS_EXPR:
case ABSU_EXPR:
case NEGATE_EXPR:
case SSA_NAME:
return true;
case INTEGER_CST:
case REAL_CST:
case VECTOR_CST:
case FIXED_CST:
return true;
default:
return false;
}
}
/* gimple_simplify_phiopt is like gimple_simplify but designed for PHIOPT.
Return NULL if nothing can be simplified or the resulting simplified value
with parts pushed if EARLY_P was true. Also rejects non allowed tree code
if EARLY_P is set.
Takes the comparison from COMP_STMT and two args, ARG0 and ARG1 and tries
to simplify CMP ? ARG0 : ARG1.
Also try to simplify (!CMP) ? ARG1 : ARG0 if the non-inverse failed. */
static tree
gimple_simplify_phiopt (bool early_p, tree type, gimple *comp_stmt,
tree arg0, tree arg1,
gimple_seq *seq)
{
gimple_seq seq1 = NULL;
enum tree_code comp_code = gimple_cond_code (comp_stmt);
location_t loc = gimple_location (comp_stmt);
tree cmp0 = gimple_cond_lhs (comp_stmt);
tree cmp1 = gimple_cond_rhs (comp_stmt);
/* To handle special cases like floating point comparison, it is easier and
less error-prone to build a tree and gimplify it on the fly though it is
less efficient.
Don't use fold_build2 here as that might create (bool)a instead of just
"a != 0". */
tree cond = build2_loc (loc, comp_code, boolean_type_node,
cmp0, cmp1);
if (dump_file && (dump_flags & TDF_FOLDING))
{
fprintf (dump_file, "\nphiopt match-simplify trying:\n\t");
print_generic_expr (dump_file, cond);
fprintf (dump_file, " ? ");
print_generic_expr (dump_file, arg0);
fprintf (dump_file, " : ");
print_generic_expr (dump_file, arg1);
fprintf (dump_file, "\n");
}
gimple_match_op op (gimple_match_cond::UNCOND,
COND_EXPR, type, cond, arg0, arg1);
if (op.resimplify (&seq1, follow_all_ssa_edges))
{
bool allowed = !early_p || phiopt_early_allow (seq1, op);
tree result = maybe_push_res_to_seq (&op, &seq1);
if (dump_file && (dump_flags & TDF_FOLDING))
{
fprintf (dump_file, "\nphiopt match-simplify back:\n");
if (seq1)
print_gimple_seq (dump_file, seq1, 0, TDF_VOPS|TDF_MEMSYMS);
fprintf (dump_file, "result: ");
if (result)
print_generic_expr (dump_file, result);
else
fprintf (dump_file, " (none)");
fprintf (dump_file, "\n");
if (!allowed)
fprintf (dump_file, "rejected because early\n");
}
/* Early we want only to allow some generated tree codes. */
if (allowed && result)
{
if (loc != UNKNOWN_LOCATION)
annotate_all_with_location (seq1, loc);
gimple_seq_add_seq_without_update (seq, seq1);
return result;
}
}
gimple_seq_discard (seq1);
seq1 = NULL;
/* Try the inverted comparison, that is !COMP ? ARG1 : ARG0. */
comp_code = invert_tree_comparison (comp_code, HONOR_NANS (cmp0));
if (comp_code == ERROR_MARK)
return NULL;
cond = build2_loc (loc,
comp_code, boolean_type_node,
cmp0, cmp1);
if (dump_file && (dump_flags & TDF_FOLDING))
{
fprintf (dump_file, "\nphiopt match-simplify trying:\n\t");
print_generic_expr (dump_file, cond);
fprintf (dump_file, " ? ");
print_generic_expr (dump_file, arg1);
fprintf (dump_file, " : ");
print_generic_expr (dump_file, arg0);
fprintf (dump_file, "\n");
}
gimple_match_op op1 (gimple_match_cond::UNCOND,
COND_EXPR, type, cond, arg1, arg0);
if (op1.resimplify (&seq1, follow_all_ssa_edges))
{
bool allowed = !early_p || phiopt_early_allow (seq1, op1);
tree result = maybe_push_res_to_seq (&op1, &seq1);
if (dump_file && (dump_flags & TDF_FOLDING))
{
fprintf (dump_file, "\nphiopt match-simplify back:\n");
if (seq1)
print_gimple_seq (dump_file, seq1, 0, TDF_VOPS|TDF_MEMSYMS);
fprintf (dump_file, "result: ");
if (result)
print_generic_expr (dump_file, result);
else
fprintf (dump_file, " (none)");
fprintf (dump_file, "\n");
if (!allowed)
fprintf (dump_file, "rejected because early\n");
}
/* Early we want only to allow some generated tree codes. */
if (allowed && result)
{
if (loc != UNKNOWN_LOCATION)
annotate_all_with_location (seq1, loc);
gimple_seq_add_seq_without_update (seq, seq1);
return result;
}
}
gimple_seq_discard (seq1);
return NULL;
}
/* empty_bb_or_one_feeding_into_p returns true if bb was empty basic block
or it has one cheap preparation statement that feeds into the PHI
statement and it sets STMT to that statement. */
static bool
empty_bb_or_one_feeding_into_p (basic_block bb,
gimple *phi,
gimple *&stmt)
{
stmt = nullptr;
gimple *stmt_to_move = nullptr;
tree lhs;
if (empty_block_p (bb))
return true;
if (!single_pred_p (bb))
return false;
/* The middle bb cannot have phi nodes as we don't
move those assignments yet. */
if (!gimple_seq_empty_p (phi_nodes (bb)))
return false;
gimple_stmt_iterator gsi;
gsi = gsi_start_nondebug_after_labels_bb (bb);
while (!gsi_end_p (gsi))
{
gimple *s = gsi_stmt (gsi);
gsi_next_nondebug (&gsi);
/* Skip over Predict and nop statements. */
if (gimple_code (s) == GIMPLE_PREDICT
|| gimple_code (s) == GIMPLE_NOP)
continue;
/* If there is more one statement return false. */
if (stmt_to_move)
return false;
stmt_to_move = s;
}
/* The only statement here was a Predict or a nop statement
so return true. */
if (!stmt_to_move)
return true;
if (gimple_vuse (stmt_to_move))
return false;
if (gimple_could_trap_p (stmt_to_move)
|| gimple_has_side_effects (stmt_to_move))
return false;
ssa_op_iter it;
tree use;
FOR_EACH_SSA_TREE_OPERAND (use, stmt_to_move, it, SSA_OP_USE)
if (ssa_name_maybe_undef_p (use))
return false;
/* Allow assignments but allow some builtin/internal calls.
As const calls don't match any of the above, yet they could
still have some side-effects - they could contain
gimple_could_trap_p statements, like floating point
exceptions or integer division by zero. See PR70586.
FIXME: perhaps gimple_has_side_effects or gimple_could_trap_p
should handle this.
Allow some known builtin/internal calls that are known not to
trap: logical functions (e.g. bswap and bit counting). */
if (!is_gimple_assign (stmt_to_move))
{
if (!is_gimple_call (stmt_to_move))
return false;
combined_fn cfn = gimple_call_combined_fn (stmt_to_move);
switch (cfn)
{
default:
return false;
case CFN_BUILT_IN_BSWAP16:
case CFN_BUILT_IN_BSWAP32:
case CFN_BUILT_IN_BSWAP64:
case CFN_BUILT_IN_BSWAP128:
CASE_CFN_FFS:
CASE_CFN_PARITY:
CASE_CFN_POPCOUNT:
CASE_CFN_CLZ:
CASE_CFN_CTZ:
case CFN_BUILT_IN_CLRSB:
case CFN_BUILT_IN_CLRSBL:
case CFN_BUILT_IN_CLRSBLL:
lhs = gimple_call_lhs (stmt_to_move);
break;
}
}
else
lhs = gimple_assign_lhs (stmt_to_move);
gimple *use_stmt;
use_operand_p use_p;
/* Allow only a statement which feeds into the other stmt. */
if (!lhs || TREE_CODE (lhs) != SSA_NAME
|| !single_imm_use (lhs, &use_p, &use_stmt)
|| use_stmt != phi)
return false;
stmt = stmt_to_move;
return true;
}
/* Move STMT to before GSI and insert its defining
name into INSERTED_EXPRS bitmap.
Also rewrite its if it might be undefined when unconditionalized. */
static void
move_stmt (gimple *stmt, gimple_stmt_iterator *gsi, auto_bitmap &inserted_exprs)
{
if (!stmt)
return;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "statement un-sinked:\n");
print_gimple_stmt (dump_file, stmt, 0,
TDF_VOPS|TDF_MEMSYMS);
}
tree name = gimple_get_lhs (stmt);
// Mark the name to be renamed if there is one.
bitmap_set_bit (inserted_exprs, SSA_NAME_VERSION (name));
gimple_stmt_iterator gsi1 = gsi_for_stmt (stmt);
gsi_move_before (&gsi1, gsi, GSI_NEW_STMT);
reset_flow_sensitive_info (name);
/* Rewrite some code which might be undefined when
unconditionalized. */
if (gimple_needing_rewrite_undefined (stmt))
rewrite_to_defined_unconditional (gsi);
}
/* RAII style class to temporarily remove flow sensitive
from ssa names defined by a gimple statement. */
class auto_flow_sensitive
{
public:
auto_flow_sensitive (gimple *s);
~auto_flow_sensitive ();
private:
auto_vec<std::pair<tree, flow_sensitive_info_storage>, 2> stack;
};
/* Constructor for auto_flow_sensitive. Saves
off the ssa names' flow sensitive information
that was defined by gimple statement S and
resets it to be non-flow based ones. */
auto_flow_sensitive::auto_flow_sensitive (gimple *s)
{
if (!s)
return;
ssa_op_iter it;
tree def;
FOR_EACH_SSA_TREE_OPERAND (def, s, it, SSA_OP_DEF)
{
flow_sensitive_info_storage storage;
storage.save_and_clear (def);
stack.safe_push (std::make_pair (def, storage));
}
}
/* Deconstructor, restores the flow sensitive information
for the SSA names that had been saved off. */
auto_flow_sensitive::~auto_flow_sensitive ()
{
for (auto p : stack)
p.second.restore (p.first);
}
/* The function match_simplify_replacement does the main work of doing the
replacement using match and simplify. Return true if the replacement is done.
Otherwise return false.
BB is the basic block where the replacement is going to be done on. ARG0
is argument 0 from PHI. Likewise for ARG1. */
static bool
match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
basic_block middle_bb_alt,
edge e0, edge e1, gphi *phi,
tree arg0, tree arg1, bool early_p,
bool threeway_p)
{
gimple *stmt;
gimple_stmt_iterator gsi;
edge true_edge, false_edge;
gimple_seq seq = NULL;
tree result;
gimple *stmt_to_move = NULL;
gimple *stmt_to_move_alt = NULL;
tree arg_true, arg_false;
/* Special case A ? B : B as this will always simplify to B. */
if (operand_equal_for_phi_arg_p (arg0, arg1))
return false;
/* If the basic block only has a cheap preparation statement,
allow it and move it once the transformation is done. */
if (!empty_bb_or_one_feeding_into_p (middle_bb, phi, stmt_to_move))
return false;
if (threeway_p
&& middle_bb != middle_bb_alt
&& !empty_bb_or_one_feeding_into_p (middle_bb_alt, phi,
stmt_to_move_alt))
return false;
/* Do not make conditional undefs unconditional. */
if ((TREE_CODE (arg0) == SSA_NAME
&& ssa_name_maybe_undef_p (arg0))
|| (TREE_CODE (arg1) == SSA_NAME
&& ssa_name_maybe_undef_p (arg1)))
return false;
/* At this point we know we have a GIMPLE_COND with two successors.
One successor is BB, the other successor is an empty block which
falls through into BB.
There is a single PHI node at the join point (BB).
So, given the condition COND, and the two PHI arguments, match and simplify
can happen on (COND) ? arg0 : arg1. */
stmt = last_nondebug_stmt (cond_bb);
/* We need to know which is the true edge and which is the false
edge so that we know when to invert the condition below. */
extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
/* Forward the edges over the middle basic block. */
if (true_edge->dest == middle_bb)
true_edge = EDGE_SUCC (true_edge->dest, 0);
if (false_edge->dest == middle_bb)
false_edge = EDGE_SUCC (false_edge->dest, 0);
/* When THREEWAY_P then e1 will point to the edge of the final transition
from middle-bb to end. */
if (true_edge == e0)
{
if (!threeway_p)
gcc_assert (false_edge == e1);
arg_true = arg0;
arg_false = arg1;
}
else
{
gcc_assert (false_edge == e0);
if (!threeway_p)
gcc_assert (true_edge == e1);
arg_true = arg1;
arg_false = arg0;
}
tree type = TREE_TYPE (gimple_phi_result (phi));
{
auto_flow_sensitive s1(stmt_to_move);
auto_flow_sensitive s_alt(stmt_to_move_alt);
result = gimple_simplify_phiopt (early_p, type, stmt,
arg_true, arg_false,
&seq);
}
if (!result)
{
/* If we don't get back a MIN/MAX_EXPR still make sure the expression
stays in a form to be recognized by ISA that map to IEEE x > y ? x : y
semantics (that's not IEEE max semantics). */
if (!HONOR_NANS (type) && !HONOR_SIGNED_ZEROS (type))
return false;
if (stmt_to_move || stmt_to_move_alt)
return false;
tree_code cmp = gimple_cond_code (stmt);
if (cmp != LT_EXPR && cmp != LE_EXPR
&& cmp != GT_EXPR && cmp != GE_EXPR)
return false;
tree lhs = gimple_cond_lhs (stmt);
tree rhs = gimple_cond_rhs (stmt);
/* `lhs CMP rhs ? lhs : rhs` or `lhs CMP rhs ? rhs : lhs`
are only acceptable case here. */
if ((!operand_equal_for_phi_arg_p (lhs, arg_false)
|| !operand_equal_for_phi_arg_p (rhs, arg_true))
&& (!operand_equal_for_phi_arg_p (rhs, arg_false)
|| !operand_equal_for_phi_arg_p (lhs, arg_true)))
return false;
seq = nullptr;
result = gimple_build (&seq, cmp, boolean_type_node, lhs, rhs);
result = gimple_build (&seq, COND_EXPR, type, result,
arg_true, arg_false);
statistics_counter_event (cfun, "Non-IEEE FP MIN/MAX PHI replacement",
1);
}
if (dump_file && (dump_flags & TDF_FOLDING))
fprintf (dump_file, "accepted the phiopt match-simplify.\n");
auto_bitmap exprs_maybe_dce;
/* Mark the cond statements' lhs/rhs as maybe dce. */
if (TREE_CODE (gimple_cond_lhs (stmt)) == SSA_NAME
&& !SSA_NAME_IS_DEFAULT_DEF (gimple_cond_lhs (stmt)))
bitmap_set_bit (exprs_maybe_dce,
SSA_NAME_VERSION (gimple_cond_lhs (stmt)));
if (TREE_CODE (gimple_cond_rhs (stmt)) == SSA_NAME
&& !SSA_NAME_IS_DEFAULT_DEF (gimple_cond_rhs (stmt)))
bitmap_set_bit (exprs_maybe_dce,
SSA_NAME_VERSION (gimple_cond_rhs (stmt)));
gsi = gsi_last_bb (cond_bb);
/* Insert the sequence generated from gimple_simplify_phiopt. */
if (seq)
{
// Mark the lhs of the new statements maybe for dce
mark_lhs_in_seq_for_dce (exprs_maybe_dce, seq);
gsi_insert_seq_before (&gsi, seq, GSI_CONTINUE_LINKING);
}
/* If there was a statement to move, move it to right before
the original conditional. */
move_stmt (stmt_to_move, &gsi, exprs_maybe_dce);
move_stmt (stmt_to_move_alt, &gsi, exprs_maybe_dce);
replace_phi_edge_with_variable (cond_bb, e1, phi, result, exprs_maybe_dce);
/* Add Statistic here even though replace_phi_edge_with_variable already
does it as we want to be able to count when match-simplify happens vs
the others. */
statistics_counter_event (cfun, "match-simplify PHI replacement", 1);
/* Note that we optimized this PHI. */
return true;
}
/* Update *ARG which is defined in STMT so that it contains the
computed value if that seems profitable. Return true if the
statement is made dead by that rewriting. */
static bool
jump_function_from_stmt (tree *arg, gimple *stmt)
{
enum tree_code code = gimple_assign_rhs_code (stmt);
if (code == ADDR_EXPR)
{
/* For arg = &p->i transform it to p, if possible. */
tree rhs1 = gimple_assign_rhs1 (stmt);
poly_int64 offset;
tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (rhs1, 0),
&offset);
if (tem
&& TREE_CODE (tem) == MEM_REF
&& known_eq (mem_ref_offset (tem) + offset, 0))
{
*arg = TREE_OPERAND (tem, 0);
return true;
}
}
/* TODO: Much like IPA-CP jump-functions we want to handle constant
additions symbolically here, and we'd need to update the comparison
code that compares the arg + cst tuples in our caller. For now the
code above exactly handles the VEC_BASE pattern from vec.h. */
return false;
}
/* RHS is a source argument in a BIT_AND_EXPR or BIT_IOR_EXPR which feeds
a conditional of the form SSA_NAME NE 0.
If RHS is fed by a simple EQ_EXPR or NE_EXPR comparison of two values,
see if the two input values of the comparison match arg0 and arg1.
If so update *code and return TRUE. Otherwise return FALSE. */
static bool
rhs_is_fed_for_value_replacement (const_tree arg0, const_tree arg1,
enum tree_code *code, const_tree rhs,
enum tree_code bit_expression_code)
{
/* Obviously if RHS is not an SSA_NAME, we can't look at the defining
statement. */
if (TREE_CODE (rhs) == SSA_NAME)
{
gimple *def1 = SSA_NAME_DEF_STMT (rhs);
/* Verify the defining statement has an EQ_EXPR or NE_EXPR on the RHS. */
if (is_gimple_assign (def1)
&& ((bit_expression_code == BIT_AND_EXPR
&& gimple_assign_rhs_code (def1) == EQ_EXPR)
|| (bit_expression_code == BIT_IOR_EXPR
&& gimple_assign_rhs_code (def1) == NE_EXPR)))
{
/* Finally verify the source operands of the EQ_EXPR or NE_EXPR
are equal to arg0 and arg1. */
tree op0 = gimple_assign_rhs1 (def1);
tree op1 = gimple_assign_rhs2 (def1);
if ((operand_equal_for_phi_arg_p (arg0, op0)
&& operand_equal_for_phi_arg_p (arg1, op1))
|| (operand_equal_for_phi_arg_p (arg0, op1)
&& operand_equal_for_phi_arg_p (arg1, op0)))
{
/* We will perform the optimization. */
*code = gimple_assign_rhs_code (def1);
return true;
}
}
}
return false;
}
/* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND.
Also return TRUE if arg0/arg1 are equal to the source arguments of an
EQ comparison feeding a BIT_AND_EXPR, or NE comparison feeding a
BIT_IOR_EXPR which feeds COND.
Return FALSE otherwise. */
static bool
operand_equal_for_value_replacement (const_tree arg0, const_tree arg1,
enum tree_code *code, gimple *cond)
{
gimple *def;
tree lhs = gimple_cond_lhs (cond);
tree rhs = gimple_cond_rhs (cond);
if ((operand_equal_for_phi_arg_p (arg0, lhs)
&& operand_equal_for_phi_arg_p (arg1, rhs))
|| (operand_equal_for_phi_arg_p (arg1, lhs)
&& operand_equal_for_phi_arg_p (arg0, rhs)))
return true;
/* Now handle more complex case where we have an EQ comparison
feeding a BIT_AND_EXPR, or a NE comparison feeding a BIT_IOR_EXPR,
which then feeds into COND.
First verify that COND is of the form SSA_NAME NE 0. */
if (*code != NE_EXPR || !integer_zerop (rhs)
|| TREE_CODE (lhs) != SSA_NAME)
return false;
/* Now ensure that SSA_NAME is set by a BIT_AND_EXPR or BIT_OR_EXPR. */
def = SSA_NAME_DEF_STMT (lhs);
if (!is_gimple_assign (def)
|| (gimple_assign_rhs_code (def) != BIT_AND_EXPR
&& gimple_assign_rhs_code (def) != BIT_IOR_EXPR))
return false;
/* Now verify arg0/arg1 correspond to the source arguments of an EQ
comparison feeding the BIT_AND_EXPR or a NE comparison feeding the
BIT_IOR_EXPR. */
tree tmp = gimple_assign_rhs1 (def);
if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp,
gimple_assign_rhs_code (def)))
return true;
tmp = gimple_assign_rhs2 (def);
if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp,
gimple_assign_rhs_code (def)))
return true;
return false;
}
/* Returns true if ARG is a neutral element for operation CODE
on the RIGHT side. */
static bool
neutral_element_p (tree_code code, tree arg, bool right)
{
switch (code)
{
case PLUS_EXPR:
case BIT_IOR_EXPR:
case BIT_XOR_EXPR:
return integer_zerop (arg);
case LROTATE_EXPR:
case RROTATE_EXPR:
case LSHIFT_EXPR:
case RSHIFT_EXPR:
case MINUS_EXPR:
case POINTER_PLUS_EXPR:
return right && integer_zerop (arg);
case MULT_EXPR:
return integer_onep (arg);
case TRUNC_DIV_EXPR:
case CEIL_DIV_EXPR:
case FLOOR_DIV_EXPR:
case ROUND_DIV_EXPR:
case EXACT_DIV_EXPR:
return right && integer_onep (arg);
case BIT_AND_EXPR:
return integer_all_onesp (arg);
default:
return false;
}
}
/* Returns true if ARG is an absorbing element for operation CODE. */
static bool
absorbing_element_p (tree_code code, tree arg, bool right, tree rval)
{
switch (code)
{
case BIT_IOR_EXPR:
return integer_all_onesp (arg);
case MULT_EXPR:
case BIT_AND_EXPR:
return integer_zerop (arg);
case LSHIFT_EXPR:
case RSHIFT_EXPR:
case LROTATE_EXPR:
case RROTATE_EXPR:
return !right && integer_zerop (arg);
case TRUNC_DIV_EXPR:
case CEIL_DIV_EXPR:
case FLOOR_DIV_EXPR:
case ROUND_DIV_EXPR:
case EXACT_DIV_EXPR:
case TRUNC_MOD_EXPR:
case CEIL_MOD_EXPR:
case FLOOR_MOD_EXPR:
case ROUND_MOD_EXPR:
return (!right
&& integer_zerop (arg)
&& tree_single_nonzero_warnv_p (rval, NULL));
default:
return false;
}
}
/* The function value_replacement does the main work of doing the value
replacement. Return non-zero if the replacement is done. Otherwise return
0. If we remove the middle basic block, return 2.
BB is the basic block where the replacement is going to be done on. ARG0
is argument 0 from the PHI. Likewise for ARG1. */
static int
value_replacement (basic_block cond_bb, basic_block middle_bb,
edge e0, edge e1, gphi *phi, tree arg0, tree arg1)
{
gimple_stmt_iterator gsi;
edge true_edge, false_edge;
enum tree_code code;
bool empty_or_with_defined_p = true;
/* Virtual operands don't need to be handled. */
if (virtual_operand_p (arg1))
return 0;
/* Special case A ? B : B as this will always simplify to B. */
if (operand_equal_for_phi_arg_p (arg0, arg1))
return 0;
gcond *cond = as_a <gcond *> (*gsi_last_bb (cond_bb));
code = gimple_cond_code (cond);
/* This transformation is only valid for equality comparisons. */
if (code != NE_EXPR && code != EQ_EXPR)
return 0;
/* Do not make conditional undefs unconditional. */
if ((TREE_CODE (arg0) == SSA_NAME
&& ssa_name_maybe_undef_p (arg0))
|| (TREE_CODE (arg1) == SSA_NAME
&& ssa_name_maybe_undef_p (arg1)))
return false;
/* If the type says honor signed zeros we cannot do this
optimization. */
if (HONOR_SIGNED_ZEROS (arg1))
return 0;
/* If there is a statement in MIDDLE_BB that defines one of the PHI
arguments, then adjust arg0 or arg1. */
gsi = gsi_start_nondebug_after_labels_bb (middle_bb);
while (!gsi_end_p (gsi))
{
gimple *stmt = gsi_stmt (gsi);
tree lhs;
gsi_next_nondebug (&gsi);
if (!is_gimple_assign (stmt))
{
if (gimple_code (stmt) != GIMPLE_PREDICT
&& gimple_code (stmt) != GIMPLE_NOP)
empty_or_with_defined_p = false;
continue;
}
/* Now try to adjust arg0 or arg1 according to the computation
in the statement. */
lhs = gimple_assign_lhs (stmt);
if (!(lhs == arg0
&& jump_function_from_stmt (&arg0, stmt))
|| (lhs == arg1
&& jump_function_from_stmt (&arg1, stmt)))
empty_or_with_defined_p = false;
}
/* The middle bb is not empty if there are any phi nodes. */
if (phi_nodes (middle_bb))
empty_or_with_defined_p = false;
/* We need to know which is the true edge and which is the false
edge so that we know if have abs or negative abs. */
extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
/* At this point we know we have a COND_EXPR with two successors.
One successor is BB, the other successor is an empty block which
falls through into BB.
The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
There is a single PHI node at the join point (BB) with two arguments.
We now need to verify that the two arguments in the PHI node match
the two arguments to the equality comparison. */
bool equal_p = operand_equal_for_value_replacement (arg0, arg1, &code, cond);
bool maybe_equal_p = false;
if (!equal_p
&& empty_or_with_defined_p
&& TREE_CODE (gimple_cond_rhs (cond)) == INTEGER_CST
&& (operand_equal_for_phi_arg_p (gimple_cond_lhs (cond), arg0)
? TREE_CODE (arg1) == INTEGER_CST
: (operand_equal_for_phi_arg_p (gimple_cond_lhs (cond), arg1)
&& TREE_CODE (arg0) == INTEGER_CST)))
maybe_equal_p = true;
if (equal_p || maybe_equal_p)
{
edge e;
tree arg;
/* For NE_EXPR, we want to build an assignment result = arg where
arg is the PHI argument associated with the true edge. For
EQ_EXPR we want the PHI argument associated with the false edge. */
e = (code == NE_EXPR ? true_edge : false_edge);
/* Unfortunately, E may not reach BB (it may instead have gone to
OTHER_BLOCK). If that is the case, then we want the single outgoing
edge from OTHER_BLOCK which reaches BB and represents the desired
path from COND_BLOCK. */
if (e->dest == middle_bb)
e = single_succ_edge (e->dest);
/* Now we know the incoming edge to BB that has the argument for the
RHS of our new assignment statement. */
if (e0 == e)
arg = arg0;
else
arg = arg1;
/* If the middle basic block was empty or is defining the
PHI arguments and this is a single phi where the args are different
for the edges e0 and e1 then we can remove the middle basic block. */
if (empty_or_with_defined_p
&& single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)),
e0, e1) == phi)
{
use_operand_p use_p;
gimple *use_stmt;
/* Even if arg0/arg1 isn't equal to second operand of cond, we
can optimize away the bb if we can prove it doesn't care whether
phi result is arg0/arg1 or second operand of cond. Consider:
<bb 2> [local count: 118111600]:
if (i_2(D) == 4)
goto <bb 4>; [97.00%]
else
goto <bb 3>; [3.00%]
<bb 3> [local count: 3540129]:
<bb 4> [local count: 118111600]:
# i_6 = PHI <i_2(D)(3), 6(2)>
_3 = i_6 != 0;
Here, carg is 4, oarg is 6, crhs is 0, and because
(4 != 0) == (6 != 0), we don't care if i_6 is 4 or 6, both
have the same outcome. So, we can optimize this to:
_3 = i_2(D) != 0;
If the single imm use of phi result >, >=, < or <=, similarly
we can check if both carg and oarg compare the same against
crhs using ccode. */
if (maybe_equal_p
&& TREE_CODE (arg) != INTEGER_CST
&& single_imm_use (gimple_phi_result (phi), &use_p, &use_stmt))
{
enum tree_code ccode = ERROR_MARK;
tree clhs = NULL_TREE, crhs = NULL_TREE;
tree carg = gimple_cond_rhs (cond);
tree oarg = e0 == e ? arg1 : arg0;
if (is_gimple_assign (use_stmt)
&& (TREE_CODE_CLASS (gimple_assign_rhs_code (use_stmt))
== tcc_comparison))
{
ccode = gimple_assign_rhs_code (use_stmt);
clhs = gimple_assign_rhs1 (use_stmt);
crhs = gimple_assign_rhs2 (use_stmt);
}
else if (gimple_code (use_stmt) == GIMPLE_COND)
{
ccode = gimple_cond_code (use_stmt);
clhs = gimple_cond_lhs (use_stmt);
crhs = gimple_cond_rhs (use_stmt);
}
if (ccode != ERROR_MARK
&& clhs == gimple_phi_result (phi)
&& TREE_CODE (crhs) == INTEGER_CST)
switch (ccode)
{
case EQ_EXPR:
case NE_EXPR:
if (!tree_int_cst_equal (crhs, carg)
&& !tree_int_cst_equal (crhs, oarg))
equal_p = true;
break;
case GT_EXPR:
if (tree_int_cst_lt (crhs, carg)
== tree_int_cst_lt (crhs, oarg))
equal_p = true;
break;
case GE_EXPR:
if (tree_int_cst_le (crhs, carg)
== tree_int_cst_le (crhs, oarg))
equal_p = true;
break;
case LT_EXPR:
if (tree_int_cst_lt (carg, crhs)
== tree_int_cst_lt (oarg, crhs))
equal_p = true;
break;
case LE_EXPR:
if (tree_int_cst_le (carg, crhs)
== tree_int_cst_le (oarg, crhs))
equal_p = true;
break;
default:
break;
}
if (equal_p)
{
tree phires = gimple_phi_result (phi);
if (SSA_NAME_RANGE_INFO (phires))
{
/* After the optimization PHI result can have value
which it couldn't have previously. */
value_range r (TREE_TYPE (phires));
if (get_global_range_query ()->range_of_expr (r, phires,
phi))
{
value_range tmp (carg, carg);
r.union_ (tmp);
reset_flow_sensitive_info (phires);
set_range_info (phires, r);
}
else
reset_flow_sensitive_info (phires);
}
}
if (equal_p && MAY_HAVE_DEBUG_BIND_STMTS)
{
imm_use_iterator imm_iter;
tree phires = gimple_phi_result (phi);
tree temp = NULL_TREE;
bool reset_p = false;
/* Add # DEBUG D#1 => arg != carg ? arg : oarg. */
FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, phires)
{
if (!is_gimple_debug (use_stmt))
continue;
if (temp == NULL_TREE)
{
if (!single_pred_p (middle_bb)
|| EDGE_COUNT (gimple_bb (phi)->preds) != 2)
{
/* But only if middle_bb has a single
predecessor and phi bb has two, otherwise
we could use a SSA_NAME not usable in that
place or wrong-debug. */
reset_p = true;
break;
}
gimple_stmt_iterator gsi
= gsi_after_labels (gimple_bb (phi));
tree type = TREE_TYPE (phires);
temp = build_debug_expr_decl (type);
tree t = build2 (NE_EXPR, boolean_type_node,
arg, carg);
t = build3 (COND_EXPR, type, t, arg, oarg);
gimple *g = gimple_build_debug_bind (temp, t, phi);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
}
FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
replace_exp (use_p, temp);
update_stmt (use_stmt);
}
if (reset_p)
reset_debug_uses (phi);
}
}
if (equal_p)
{
replace_phi_edge_with_variable (cond_bb, e1, phi, arg);
/* Note that we optimized this PHI. */
return 2;
}
}
else if (equal_p)
{
if (!single_pred_p (middle_bb))
return 0;
statistics_counter_event (cfun, "Replace PHI with "
"variable/value_replacement", 1);
/* Replace the PHI arguments with arg. */
SET_PHI_ARG_DEF (phi, e0->dest_idx, arg);
SET_PHI_ARG_DEF (phi, e1->dest_idx, arg);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "PHI ");
print_generic_expr (dump_file, gimple_phi_result (phi));
fprintf (dump_file, " reduced for COND_EXPR in block %d to ",
cond_bb->index);
print_generic_expr (dump_file, arg);
fprintf (dump_file, ".\n");
}
return 1;
}
}
if (!single_pred_p (middle_bb))
return 0;
/* Now optimize (x != 0) ? x + y : y to just x + y. */
gsi = gsi_last_nondebug_bb (middle_bb);
if (gsi_end_p (gsi))
return 0;
gimple *assign = gsi_stmt (gsi);
if (!is_gimple_assign (assign)
|| (!INTEGRAL_TYPE_P (TREE_TYPE (arg0))
&& !POINTER_TYPE_P (TREE_TYPE (arg0))))
return 0;
if (gimple_assign_rhs_class (assign) != GIMPLE_BINARY_RHS)
{
/* If last stmt of the middle_bb is a conversion, handle it like
a preparation statement through constant evaluation with
checking for UB. */
enum tree_code sc = gimple_assign_rhs_code (assign);
if (CONVERT_EXPR_CODE_P (sc))
assign = NULL;
else
return 0;
}
/* Punt if there are (degenerate) PHIs in middle_bb, there should not be. */
if (!gimple_seq_empty_p (phi_nodes (middle_bb)))
return 0;
/* Allow up to 2 cheap preparation statements that prepare argument
for assign, e.g.:
if (y_4 != 0)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
_1 = (int) y_4;
iftmp.0_6 = x_5(D) r<< _1;
<bb 4>:
# iftmp.0_2 = PHI <iftmp.0_6(3), x_5(D)(2)>
or:
if (y_3(D) == 0)
goto <bb 4>;
else
goto <bb 3>;
<bb 3>:
y_4 = y_3(D) & 31;
_1 = (int) y_4;
_6 = x_5(D) r<< _1;
<bb 4>:
# _2 = PHI <x_5(D)(2), _6(3)> */
gimple *prep_stmt[2] = { NULL, NULL };
int prep_cnt;
for (prep_cnt = 0; ; prep_cnt++)
{
if (prep_cnt || assign)
gsi_prev_nondebug (&gsi);
if (gsi_end_p (gsi))
break;
gimple *g = gsi_stmt (gsi);
if (gimple_code (g) == GIMPLE_LABEL)
break;
if (prep_cnt == 2 || !is_gimple_assign (g))
return 0;
tree lhs = gimple_assign_lhs (g);
tree rhs1 = gimple_assign_rhs1 (g);
use_operand_p use_p;
gimple *use_stmt;
if (TREE_CODE (lhs) != SSA_NAME
|| TREE_CODE (rhs1) != SSA_NAME
|| !INTEGRAL_TYPE_P (TREE_TYPE (lhs))
|| !INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
|| !single_imm_use (lhs, &use_p, &use_stmt)
|| ((prep_cnt || assign)
&& use_stmt != (prep_cnt ? prep_stmt[prep_cnt - 1] : assign)))
return 0;
switch (gimple_assign_rhs_code (g))
{
CASE_CONVERT:
break;
case PLUS_EXPR:
case BIT_AND_EXPR:
case BIT_IOR_EXPR:
case BIT_XOR_EXPR:
if (TREE_CODE (gimple_assign_rhs2 (g)) != INTEGER_CST)
return 0;
break;
default:
return 0;
}
prep_stmt[prep_cnt] = g;
}
/* Only transform if it removes the condition. */
if (!single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)), e0, e1))
return 0;
/* Size-wise, this is always profitable. */
if (optimize_bb_for_speed_p (cond_bb)
/* The special case is useless if it has a low probability. */
&& profile_status_for_fn (cfun) != PROFILE_ABSENT
&& EDGE_PRED (middle_bb, 0)->probability < profile_probability::even ()
/* If assign is cheap, there is no point avoiding it. */
&& estimate_num_insns_seq (bb_seq (middle_bb), &eni_time_weights)
>= 3 * estimate_num_insns (cond, &eni_time_weights))
return 0;
tree cond_lhs = gimple_cond_lhs (cond);
tree cond_rhs = gimple_cond_rhs (cond);
/* Propagate the cond_rhs constant through preparation stmts,
make sure UB isn't invoked while doing that. */
for (int i = prep_cnt - 1; i >= 0; --i)
{
gimple *g = prep_stmt[i];
tree grhs1 = gimple_assign_rhs1 (g);
if (!operand_equal_for_phi_arg_p (cond_lhs, grhs1))
return 0;
cond_lhs = gimple_assign_lhs (g);
cond_rhs = fold_convert (TREE_TYPE (grhs1), cond_rhs);
if (TREE_CODE (cond_rhs) != INTEGER_CST
|| TREE_OVERFLOW (cond_rhs))
return 0;
if (gimple_assign_rhs_class (g) == GIMPLE_BINARY_RHS)
{
cond_rhs = int_const_binop (gimple_assign_rhs_code (g), cond_rhs,
gimple_assign_rhs2 (g));
if (TREE_OVERFLOW (cond_rhs))
return 0;
}
cond_rhs = fold_convert (TREE_TYPE (cond_lhs), cond_rhs);
if (TREE_CODE (cond_rhs) != INTEGER_CST
|| TREE_OVERFLOW (cond_rhs))
return 0;
}
tree lhs, rhs1, rhs2;
enum tree_code code_def;
if (assign)
{
lhs = gimple_assign_lhs (assign);
rhs1 = gimple_assign_rhs1 (assign);
rhs2 = gimple_assign_rhs2 (assign);
code_def = gimple_assign_rhs_code (assign);
}
else
{
gcc_assert (prep_cnt > 0);
lhs = cond_lhs;
rhs1 = NULL_TREE;
rhs2 = NULL_TREE;
code_def = ERROR_MARK;
}
if (((code == NE_EXPR && e1 == false_edge)
|| (code == EQ_EXPR && e1 == true_edge))
&& arg0 == lhs
&& ((assign == NULL
&& operand_equal_for_phi_arg_p (arg1, cond_rhs))
|| (assign
&& arg1 == rhs1
&& operand_equal_for_phi_arg_p (rhs2, cond_lhs)
&& neutral_element_p (code_def, cond_rhs, true))
|| (assign
&& arg1 == rhs2
&& operand_equal_for_phi_arg_p (rhs1, cond_lhs)
&& neutral_element_p (code_def, cond_rhs, false))
|| (assign
&& operand_equal_for_phi_arg_p (arg1, cond_rhs)
&& ((operand_equal_for_phi_arg_p (rhs2, cond_lhs)
&& absorbing_element_p (code_def, cond_rhs, true, rhs2))
|| (operand_equal_for_phi_arg_p (rhs1, cond_lhs)
&& absorbing_element_p (code_def,
cond_rhs, false, rhs2))))))
{
gsi = gsi_for_stmt (cond);
/* Moving ASSIGN might change VR of lhs, e.g. when moving u_6
def-stmt in:
if (n_5 != 0)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
# RANGE [0, 4294967294]
u_6 = n_5 + 4294967295;
<bb 4>:
# u_3 = PHI <u_6(3), 4294967295(2)> */
reset_flow_sensitive_info (lhs);
gimple_stmt_iterator gsi_from;
for (int i = prep_cnt - 1; i >= 0; --i)
{
tree plhs = gimple_assign_lhs (prep_stmt[i]);
reset_flow_sensitive_info (plhs);
gsi_from = gsi_for_stmt (prep_stmt[i]);
gsi_move_before (&gsi_from, &gsi);
}
if (assign)
{
gsi_from = gsi_for_stmt (assign);
gsi_move_before (&gsi_from, &gsi);
}
replace_phi_edge_with_variable (cond_bb, e1, phi, lhs);
return 2;
}
return 0;
}
/* Attempt to optimize (x <=> y) cmp 0 and similar comparisons.
For strong ordering <=> try to match something like:
<bb 2> : // cond3_bb (== cond2_bb)
if (x_4(D) != y_5(D))
goto <bb 3>; [INV]
else
goto <bb 6>; [INV]
<bb 3> : // cond_bb
if (x_4(D) < y_5(D))
goto <bb 6>; [INV]
else
goto <bb 4>; [INV]
<bb 4> : // middle_bb
<bb 6> : // phi_bb
# iftmp.0_2 = PHI <1(4), 0(2), -1(3)>
_1 = iftmp.0_2 == 0;
and for partial ordering <=> something like:
<bb 2> : // cond3_bb
if (a_3(D) == b_5(D))
goto <bb 6>; [50.00%]
else
goto <bb 3>; [50.00%]
<bb 3> [local count: 536870913]: // cond2_bb
if (a_3(D) < b_5(D))
goto <bb 6>; [50.00%]
else
goto <bb 4>; [50.00%]
<bb 4> [local count: 268435456]: // cond_bb
if (a_3(D) > b_5(D))
goto <bb 6>; [50.00%]
else
goto <bb 5>; [50.00%]
<bb 5> [local count: 134217728]: // middle_bb
<bb 6> [local count: 1073741824]: // phi_bb
# SR.27_4 = PHI <0(2), -1(3), 1(4), -128(5)>
_2 = SR.27_4 > 0; */
static bool
spaceship_replacement (basic_block cond_bb, basic_block middle_bb,
edge e0, edge e1, gphi *phi,
tree arg0, tree arg1)
{
tree phires = gimple_phi_result (phi);
if (!INTEGRAL_TYPE_P (TREE_TYPE (phires))
|| TYPE_UNSIGNED (TREE_TYPE (phires))
|| !tree_fits_shwi_p (arg0)
|| !tree_fits_shwi_p (arg1)
|| (!IN_RANGE (tree_to_shwi (arg0), -1, 1)
&& tree_to_shwi (arg0) != -128)
|| (!IN_RANGE (tree_to_shwi (arg1), -1, 1)
&& tree_to_shwi (arg1) != -128))
return false;
basic_block phi_bb = gimple_bb (phi);
gcc_assert (phi_bb == e0->dest && phi_bb == e1->dest);
if (!IN_RANGE (EDGE_COUNT (phi_bb->preds), 3, 4))
return false;
use_operand_p use_p;
gimple *use_stmt;
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (phires))
return false;
if (!single_imm_use (phires, &use_p, &use_stmt))
return false;
enum tree_code cmp;
tree lhs, rhs;
gimple *orig_use_stmt = use_stmt;
tree orig_use_lhs = NULL_TREE;
tree temps[2] = { NULL_TREE, NULL_TREE };
/* Handle std::partial_ordering::_M_reverse(), i.e.
_1 = (unsigned char) phires;
_2 = -_1;
_3 = (signed char) _2;
and uses of _3 in comparison instead of phires. */
if (gimple_assign_cast_p (use_stmt))
{
orig_use_lhs = gimple_assign_lhs (use_stmt);
temps[0] = orig_use_lhs;
tree ty1 = TREE_TYPE (gimple_assign_rhs1 (use_stmt));
tree ty2 = TREE_TYPE (orig_use_lhs);
if (!TYPE_UNSIGNED (ty2) || !INTEGRAL_TYPE_P (ty2))
return false;
if (TYPE_PRECISION (ty2) != 8 || TYPE_PRECISION (ty1) < 8)
return false;
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig_use_lhs))
return false;
if (!single_imm_use (orig_use_lhs, &use_p, &use_stmt))
return false;
if (!is_gimple_assign (use_stmt)
|| gimple_assign_rhs_code (use_stmt) != NEGATE_EXPR)
return false;
orig_use_lhs = gimple_assign_lhs (use_stmt);
temps[1] = orig_use_lhs;
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig_use_lhs))
return false;
if (!single_imm_use (orig_use_lhs, &use_p, &use_stmt))
return false;
if (!gimple_assign_cast_p (use_stmt))
return false;
orig_use_lhs = gimple_assign_lhs (use_stmt);
tree ty3 = TREE_TYPE (orig_use_lhs);
if (!useless_type_conversion_p (ty3, ty1))
return false;
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig_use_lhs))
return false;
if (!single_imm_use (orig_use_lhs, &use_p, &use_stmt))
return false;
}
if (gimple_code (use_stmt) == GIMPLE_COND)
{
cmp = gimple_cond_code (use_stmt);
lhs = gimple_cond_lhs (use_stmt);
rhs = gimple_cond_rhs (use_stmt);
}
else if (is_gimple_assign (use_stmt))
{
if (gimple_assign_rhs_class (use_stmt) == GIMPLE_BINARY_RHS)
{
cmp = gimple_assign_rhs_code (use_stmt);
lhs = gimple_assign_rhs1 (use_stmt);
rhs = gimple_assign_rhs2 (use_stmt);
}
else if (gimple_assign_rhs_code (use_stmt) == COND_EXPR)
{
tree cond = gimple_assign_rhs1 (use_stmt);
if (!COMPARISON_CLASS_P (cond))
return false;
cmp = TREE_CODE (cond);
lhs = TREE_OPERAND (cond, 0);
rhs = TREE_OPERAND (cond, 1);
}
else
return false;
}
else
return false;
switch (cmp)
{
case EQ_EXPR:
case NE_EXPR:
case LT_EXPR:
case GT_EXPR:
case LE_EXPR:
case GE_EXPR:
break;
default:
return false;
}
if (lhs != (orig_use_lhs ? orig_use_lhs : phires)
|| !tree_fits_shwi_p (rhs)
|| !IN_RANGE (tree_to_shwi (rhs), -1, 1))
return false;
if (!empty_block_p (middle_bb))
return false;
gcond *cond1 = as_a <gcond *> (*gsi_last_bb (cond_bb));
enum tree_code cmp1 = gimple_cond_code (cond1);
switch (cmp1)
{
case LT_EXPR:
case LE_EXPR:
case GT_EXPR:
case GE_EXPR:
break;
default:
return false;
}
tree lhs1 = gimple_cond_lhs (cond1);
tree rhs1 = gimple_cond_rhs (cond1);
if (TREE_CODE (lhs1) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs1))
return false;
if (TREE_CODE (rhs1) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs1))
return false;
if (!single_pred_p (cond_bb) || !cond_only_block_p (cond_bb))
return false;
basic_block cond2_bb = single_pred (cond_bb);
if (EDGE_COUNT (cond2_bb->succs) != 2)
return false;
edge cond2_phi_edge;
if (EDGE_SUCC (cond2_bb, 0)->dest == cond_bb)
{
if (EDGE_SUCC (cond2_bb, 1)->dest != phi_bb)
return false;
cond2_phi_edge = EDGE_SUCC (cond2_bb, 1);
}
else if (EDGE_SUCC (cond2_bb, 0)->dest != phi_bb)
return false;
else
cond2_phi_edge = EDGE_SUCC (cond2_bb, 0);
tree arg2 = gimple_phi_arg_def (phi, cond2_phi_edge->dest_idx);
if (!tree_fits_shwi_p (arg2))
return false;
gcond *cond2 = safe_dyn_cast <gcond *> (*gsi_last_bb (cond2_bb));
if (!cond2)
return false;
enum tree_code cmp2 = gimple_cond_code (cond2);
tree lhs2 = gimple_cond_lhs (cond2);
tree rhs2 = gimple_cond_rhs (cond2);
if (lhs2 == lhs1)
{
if (!operand_equal_p (rhs2, rhs1, 0))
{
if ((cmp2 == EQ_EXPR || cmp2 == NE_EXPR)
&& TREE_CODE (rhs1) == INTEGER_CST
&& TREE_CODE (rhs2) == INTEGER_CST)
{
/* For integers, we can have cond2 x == 5
and cond1 x < 5, x <= 4, x <= 5, x < 6,
x > 5, x >= 6, x >= 5 or x > 4. */
if (tree_int_cst_lt (rhs1, rhs2))
{
if (wi::ne_p (wi::to_wide (rhs1) + 1, wi::to_wide (rhs2)))
return false;
if (cmp1 == LE_EXPR)
cmp1 = LT_EXPR;
else if (cmp1 == GT_EXPR)
cmp1 = GE_EXPR;
else
return false;
}
else
{
gcc_checking_assert (tree_int_cst_lt (rhs2, rhs1));
if (wi::ne_p (wi::to_wide (rhs2) + 1, wi::to_wide (rhs1)))
return false;
if (cmp1 == LT_EXPR)
cmp1 = LE_EXPR;
else if (cmp1 == GE_EXPR)
cmp1 = GT_EXPR;
else
return false;
}
rhs1 = rhs2;
}
else
return false;
}
}
else if (lhs2 == rhs1)
{
if (rhs2 != lhs1)
return false;
}
else
return false;
tree arg3 = arg2;
basic_block cond3_bb = cond2_bb;
edge cond3_phi_edge = cond2_phi_edge;
gcond *cond3 = cond2;
enum tree_code cmp3 = cmp2;
tree lhs3 = lhs2;
tree rhs3 = rhs2;
if (EDGE_COUNT (phi_bb->preds) == 4)
{
if (absu_hwi (tree_to_shwi (arg2)) != 1)
return false;
if ((cond2_phi_edge->flags & EDGE_FALSE_VALUE)
&& HONOR_NANS (TREE_TYPE (lhs1)))
return false;
if (e1->flags & EDGE_TRUE_VALUE)
{
if (tree_to_shwi (arg0) != -128
|| absu_hwi (tree_to_shwi (arg1)) != 1
|| wi::to_widest (arg1) == wi::to_widest (arg2))
return false;
}
else if (tree_to_shwi (arg1) != -128
|| absu_hwi (tree_to_shwi (arg0)) != 1
|| wi::to_widest (arg0) == wi::to_widest (arg2))
return false;
switch (cmp2)
{
case LT_EXPR:
case LE_EXPR:
case GT_EXPR:
case GE_EXPR:
break;
default:
return false;
}
/* if (x < y) goto phi_bb; else fallthru;
if (x > y) goto phi_bb; else fallthru;
bbx:;
phi_bb:;
is ok, but if x and y are swapped in one of the comparisons,
or the comparisons are the same and operands not swapped,
or the true and false edges are swapped, it is not.
For HONOR_NANS, the edge flags are irrelevant and the comparisons
must be different for non-swapped operands and same for swapped
operands. */
if ((lhs2 == lhs1)
^ (HONOR_NANS (TREE_TYPE (lhs1))
? ((cmp2 == LT_EXPR || cmp2 == LE_EXPR)
!= (cmp1 == LT_EXPR || cmp1 == LE_EXPR))
: (((cond2_phi_edge->flags
& ((cmp2 == LT_EXPR || cmp2 == LE_EXPR)
? EDGE_TRUE_VALUE : EDGE_FALSE_VALUE)) != 0)
!= ((e1->flags
& ((cmp1 == LT_EXPR || cmp1 == LE_EXPR)
? EDGE_TRUE_VALUE : EDGE_FALSE_VALUE)) != 0))))
return false;
if (!single_pred_p (cond2_bb) || !cond_only_block_p (cond2_bb))
return false;
cond3_bb = single_pred (cond2_bb);
if (EDGE_COUNT (cond2_bb->succs) != 2)
return false;
if (EDGE_SUCC (cond3_bb, 0)->dest == cond2_bb)
{
if (EDGE_SUCC (cond3_bb, 1)->dest != phi_bb)
return false;
cond3_phi_edge = EDGE_SUCC (cond3_bb, 1);
}
else if (EDGE_SUCC (cond3_bb, 0)->dest != phi_bb)
return false;
else
cond3_phi_edge = EDGE_SUCC (cond3_bb, 0);
arg3 = gimple_phi_arg_def (phi, cond3_phi_edge->dest_idx);
cond3 = safe_dyn_cast <gcond *> (*gsi_last_bb (cond3_bb));
if (!cond3)
return false;
cmp3 = gimple_cond_code (cond3);
lhs3 = gimple_cond_lhs (cond3);
rhs3 = gimple_cond_rhs (cond3);
if (lhs3 == lhs1)
{
if (!operand_equal_p (rhs3, rhs1, 0))
return false;
}
else if (lhs3 == rhs1)
{
if (rhs3 != lhs1)
return false;
}
else
return false;
}
else if (absu_hwi (tree_to_shwi (arg0)) != 1
|| absu_hwi (tree_to_shwi (arg1)) != 1
|| wi::to_widest (arg0) == wi::to_widest (arg1)
|| HONOR_NANS (TREE_TYPE (lhs1)))
return false;
if (!integer_zerop (arg3) || (cmp3 != EQ_EXPR && cmp3 != NE_EXPR))
return false;
if ((cond3_phi_edge->flags & (cmp3 == EQ_EXPR
? EDGE_TRUE_VALUE : EDGE_FALSE_VALUE)) == 0)
return false;
/* lhs1 one_cmp rhs1 results in phires of 1. */
enum tree_code one_cmp;
if ((cmp1 == LT_EXPR || cmp1 == LE_EXPR)
^ (!integer_onep ((e1->flags & EDGE_TRUE_VALUE) ? arg1 : arg0)))
one_cmp = LT_EXPR;
else
one_cmp = GT_EXPR;
enum tree_code res_cmp;
bool negate_p = false;
switch (cmp)
{
case EQ_EXPR:
if (integer_zerop (rhs) && !HONOR_NANS (TREE_TYPE (lhs1)))
res_cmp = EQ_EXPR;
else if (integer_minus_onep (rhs))
res_cmp = one_cmp == LT_EXPR ? GT_EXPR : LT_EXPR;
else if (integer_onep (rhs))
res_cmp = one_cmp;
else
return false;
break;
case NE_EXPR:
if (integer_zerop (rhs) && !HONOR_NANS (TREE_TYPE (lhs1)))
res_cmp = NE_EXPR;
else if (integer_minus_onep (rhs))
res_cmp = one_cmp == LT_EXPR ? LE_EXPR : GE_EXPR;
else if (integer_onep (rhs))
res_cmp = one_cmp == LT_EXPR ? GE_EXPR : LE_EXPR;
else
return false;
if (HONOR_NANS (TREE_TYPE (lhs1)))
negate_p = true;
break;
case LT_EXPR:
if (integer_onep (rhs))
res_cmp = one_cmp == LT_EXPR ? GE_EXPR : LE_EXPR;
else if (integer_zerop (rhs))
res_cmp = one_cmp == LT_EXPR ? GT_EXPR : LT_EXPR;
else
return false;
if (HONOR_NANS (TREE_TYPE (lhs1)))
negate_p = true;
break;
case LE_EXPR:
if (integer_zerop (rhs))
res_cmp = one_cmp == LT_EXPR ? GE_EXPR : LE_EXPR;
else if (integer_minus_onep (rhs))
res_cmp = one_cmp == LT_EXPR ? GT_EXPR : LT_EXPR;
else
return false;
if (HONOR_NANS (TREE_TYPE (lhs1)))
negate_p = true;
break;
case GT_EXPR:
if (integer_minus_onep (rhs))
res_cmp = one_cmp == LT_EXPR ? LE_EXPR : GE_EXPR;
else if (integer_zerop (rhs))
res_cmp = one_cmp;
else
return false;
break;
case GE_EXPR:
if (integer_zerop (rhs))
res_cmp = one_cmp == LT_EXPR ? LE_EXPR : GE_EXPR;
else if (integer_onep (rhs))
res_cmp = one_cmp;
else
return false;
break;
default:
gcc_unreachable ();
}
if (orig_use_lhs)
res_cmp = swap_tree_comparison (res_cmp);
tree clhs1 = lhs1, crhs1 = rhs1;
if (negate_p)
{
if (cfun->can_throw_non_call_exceptions)
return false;
res_cmp = invert_tree_comparison (res_cmp, false);
clhs1 = make_ssa_name (boolean_type_node);
gimple *g = gimple_build_assign (clhs1, res_cmp, lhs1, rhs1);
gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
crhs1 = boolean_false_node;
res_cmp = EQ_EXPR;
}
if (gimple_code (use_stmt) == GIMPLE_COND)
{
gcond *use_cond = as_a <gcond *> (use_stmt);
gimple_cond_set_code (use_cond, res_cmp);
gimple_cond_set_lhs (use_cond, clhs1);
gimple_cond_set_rhs (use_cond, crhs1);
}
else if (gimple_assign_rhs_class (use_stmt) == GIMPLE_BINARY_RHS)
{
gimple_assign_set_rhs_code (use_stmt, res_cmp);
gimple_assign_set_rhs1 (use_stmt, clhs1);
gimple_assign_set_rhs2 (use_stmt, crhs1);
}
else
{
tree cond = build2 (res_cmp, TREE_TYPE (gimple_assign_rhs1 (use_stmt)),
clhs1, crhs1);
gimple_assign_set_rhs1 (use_stmt, cond);
}
update_stmt (use_stmt);
if (MAY_HAVE_DEBUG_BIND_STMTS)
{
use_operand_p use_p;
imm_use_iterator iter;
bool has_debug_uses = false;
bool has_cast1_debug_uses = false;
bool has_neg_debug_uses = false;
bool has_cast2_debug_uses = false;
FOR_EACH_IMM_USE_FAST (use_p, iter, phires)
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
{
has_debug_uses = true;
break;
}
}
if (orig_use_lhs)
{
FOR_EACH_IMM_USE_FAST (use_p, iter, temps[0])
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
{
has_debug_uses = true;
has_cast1_debug_uses = true;
break;
}
}
FOR_EACH_IMM_USE_FAST (use_p, iter, temps[1])
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
{
has_debug_uses = true;
has_cast1_debug_uses = true;
has_neg_debug_uses = true;
break;
}
}
FOR_EACH_IMM_USE_FAST (use_p, iter, orig_use_lhs)
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
{
has_debug_uses = true;
has_cast1_debug_uses = true;
has_neg_debug_uses = true;
has_cast2_debug_uses = true;
break;
}
}
if (has_debug_uses)
{
gimple_stmt_iterator gsi = gsi_for_stmt (orig_use_stmt);
tree zero = build_zero_cst (TREE_TYPE (temps[0]));
gimple_assign_set_rhs_with_ops (&gsi, INTEGER_CST, zero);
update_stmt (orig_use_stmt);
gsi = gsi_for_stmt (SSA_NAME_DEF_STMT (temps[1]));
zero = build_zero_cst (TREE_TYPE (temps[1]));
gimple_assign_set_rhs_with_ops (&gsi, INTEGER_CST, zero);
update_stmt (SSA_NAME_DEF_STMT (temps[1]));
gsi = gsi_for_stmt (SSA_NAME_DEF_STMT (orig_use_lhs));
zero = build_zero_cst (TREE_TYPE (orig_use_lhs));
gimple_assign_set_rhs_with_ops (&gsi, INTEGER_CST, zero);
update_stmt (SSA_NAME_DEF_STMT (orig_use_lhs));
}
}
if (has_debug_uses)
{
/* If there are debug uses, emit something like:
# DEBUG D#1 => i_2(D) > j_3(D) ? 1 : -1
# DEBUG D#2 => i_2(D) == j_3(D) ? 0 : D#1
where > stands for the comparison that yielded 1
and replace debug uses of phi result with that D#2.
Ignore the value of -128 if !HONOR_NANS, because if NaNs
aren't expected, all floating point numbers should be
comparable. If HONOR_NANS, emit something like:
# DEBUG D#1 => i_2(D) < j_3(D) ? -1 : -128
# DEBUG D#2 => i_2(D) > j_3(D) ? 1 : D#1
# DEBUG D#3 => i_2(D) == j_3(D) ? 0 : D#2
instead. */
gimple_stmt_iterator gsi = gsi_after_labels (gimple_bb (phi));
tree type = TREE_TYPE (phires);
tree minus_one = build_int_cst (type, -1);
if (HONOR_NANS (TREE_TYPE (lhs1)))
{
tree temp3 = build_debug_expr_decl (type);
tree t = build2 (one_cmp == LT_EXPR ? GT_EXPR : LT_EXPR,
boolean_type_node, lhs1, rhs2);
t = build3 (COND_EXPR, type, t, minus_one,
build_int_cst (type, -128));
gimple *g = gimple_build_debug_bind (temp3, t, phi);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
minus_one = temp3;
}
tree temp1 = build_debug_expr_decl (type);
tree t = build2 (one_cmp, boolean_type_node, lhs1, rhs2);
t = build3 (COND_EXPR, type, t, build_one_cst (type),
minus_one);
gimple *g = gimple_build_debug_bind (temp1, t, phi);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
tree temp2 = build_debug_expr_decl (type);
t = build2 (EQ_EXPR, boolean_type_node, lhs1, rhs2);
t = build3 (COND_EXPR, type, t, build_zero_cst (type), temp1);
g = gimple_build_debug_bind (temp2, t, phi);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
replace_uses_by (phires, temp2);
if (has_cast1_debug_uses)
{
tree temp3 = build_debug_expr_decl (TREE_TYPE (temps[0]));
t = fold_convert (TREE_TYPE (temps[0]), temp2);
g = gimple_build_debug_bind (temp3, t, phi);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
replace_uses_by (temps[0], temp3);
temp2 = temp3;
}
if (has_neg_debug_uses)
{
tree temp3 = build_debug_expr_decl (TREE_TYPE (temps[1]));
t = fold_build1 (NEGATE_EXPR, TREE_TYPE (temps[1]), temp2);
g = gimple_build_debug_bind (temp3, t, phi);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
replace_uses_by (temps[1], temp3);
temp2 = temp3;
}
if (has_cast2_debug_uses)
{
tree temp3 = build_debug_expr_decl (TREE_TYPE (orig_use_lhs));
t = fold_convert (TREE_TYPE (orig_use_lhs), temp2);
g = gimple_build_debug_bind (temp3, t, phi);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
replace_uses_by (orig_use_lhs, temp3);
}
}
}
if (orig_use_lhs)
{
gimple_stmt_iterator gsi = gsi_for_stmt (SSA_NAME_DEF_STMT (orig_use_lhs));
gsi_remove (&gsi, true);
gsi = gsi_for_stmt (SSA_NAME_DEF_STMT (temps[1]));
gsi_remove (&gsi, true);
gsi = gsi_for_stmt (orig_use_stmt);
gsi_remove (&gsi, true);
release_ssa_name (orig_use_lhs);
release_ssa_name (temps[1]);
release_ssa_name (temps[0]);
}
gimple_stmt_iterator psi = gsi_for_stmt (phi);
remove_phi_node (&psi, true);
statistics_counter_event (cfun, "spaceship replacement", 1);
return true;
}
/* Optimize x ? __builtin_fun (x) : C, where C is __builtin_fun (0).
Convert
<bb 2>
if (b_4(D) != 0)
goto <bb 3>
else
goto <bb 4>
<bb 3>
_2 = (unsigned long) b_4(D);
_9 = __builtin_popcountl (_2);
OR
_9 = __builtin_popcountl (b_4(D));
<bb 4>
c_12 = PHI <0(2), _9(3)>
Into
<bb 2>
_2 = (unsigned long) b_4(D);
_9 = __builtin_popcountl (_2);
OR
_9 = __builtin_popcountl (b_4(D));
<bb 4>
c_12 = PHI <_9(2)>
Similarly for __builtin_clz or __builtin_ctz if
C?Z_DEFINED_VALUE_AT_ZERO is 2, optab is present and
instead of 0 above it uses the value from that macro. */
static bool
cond_removal_in_builtin_zero_pattern (basic_block cond_bb,
basic_block middle_bb,
edge e1, edge e2, gphi *phi,
tree arg0, tree arg1)
{
gimple_stmt_iterator gsi, gsi_from;
gimple *call;
gimple *cast = NULL;
tree lhs, arg;
/* Check that
_2 = (unsigned long) b_4(D);
_9 = __builtin_popcountl (_2);
OR
_9 = __builtin_popcountl (b_4(D));
are the only stmts in the middle_bb. */
gsi = gsi_start_nondebug_after_labels_bb (middle_bb);
if (gsi_end_p (gsi))
return false;
cast = gsi_stmt (gsi);
gsi_next_nondebug (&gsi);
if (!gsi_end_p (gsi))
{
call = gsi_stmt (gsi);
gsi_next_nondebug (&gsi);
if (!gsi_end_p (gsi))
return false;
}
else
{
call = cast;
cast = NULL;
}
/* Check that we have a popcount/clz/ctz builtin. */
if (!is_gimple_call (call))
return false;
lhs = gimple_get_lhs (call);
if (lhs == NULL_TREE)
return false;
combined_fn cfn = gimple_call_combined_fn (call);
if (gimple_call_num_args (call) != 1
&& (gimple_call_num_args (call) != 2
|| cfn == CFN_CLZ
|| cfn == CFN_CTZ))
return false;
arg = gimple_call_arg (call, 0);
internal_fn ifn = IFN_LAST;
int val = 0;
bool any_val = false;
switch (cfn)
{
case CFN_BUILT_IN_BSWAP16:
case CFN_BUILT_IN_BSWAP32:
case CFN_BUILT_IN_BSWAP64:
case CFN_BUILT_IN_BSWAP128:
CASE_CFN_FFS:
CASE_CFN_PARITY:
CASE_CFN_POPCOUNT:
break;
CASE_CFN_CLZ:
if (INTEGRAL_TYPE_P (TREE_TYPE (arg)))
{
tree type = TREE_TYPE (arg);
if (TREE_CODE (type) == BITINT_TYPE)
{
if (gimple_call_num_args (call) == 1)
{
any_val = true;
ifn = IFN_CLZ;
break;
}
if (!tree_fits_shwi_p (gimple_call_arg (call, 1)))
return false;
HOST_WIDE_INT at_zero = tree_to_shwi (gimple_call_arg (call, 1));
if ((int) at_zero != at_zero)
return false;
ifn = IFN_CLZ;
val = at_zero;
break;
}
if (direct_internal_fn_supported_p (IFN_CLZ, type, OPTIMIZE_FOR_BOTH)
&& CLZ_DEFINED_VALUE_AT_ZERO (SCALAR_INT_TYPE_MODE (type),
val) == 2)
{
ifn = IFN_CLZ;
break;
}
}
return false;
CASE_CFN_CTZ:
if (INTEGRAL_TYPE_P (TREE_TYPE (arg)))
{
tree type = TREE_TYPE (arg);
if (TREE_CODE (type) == BITINT_TYPE)
{
if (gimple_call_num_args (call) == 1)
{
any_val = true;
ifn = IFN_CTZ;
break;
}
if (!tree_fits_shwi_p (gimple_call_arg (call, 1)))
return false;
HOST_WIDE_INT at_zero = tree_to_shwi (gimple_call_arg (call, 1));
if ((int) at_zero != at_zero)
return false;
ifn = IFN_CTZ;
val = at_zero;
break;
}
if (direct_internal_fn_supported_p (IFN_CTZ, type, OPTIMIZE_FOR_BOTH)
&& CTZ_DEFINED_VALUE_AT_ZERO (SCALAR_INT_TYPE_MODE (type),
val) == 2)
{
ifn = IFN_CTZ;
break;
}
}
return false;
case CFN_BUILT_IN_CLRSB:
val = TYPE_PRECISION (integer_type_node) - 1;
break;
case CFN_BUILT_IN_CLRSBL:
val = TYPE_PRECISION (long_integer_type_node) - 1;
break;
case CFN_BUILT_IN_CLRSBLL:
val = TYPE_PRECISION (long_long_integer_type_node) - 1;
break;
default:
return false;
}
if (cast)
{
/* We have a cast stmt feeding popcount/clz/ctz builtin. */
/* Check that we have a cast prior to that. */
if (gimple_code (cast) != GIMPLE_ASSIGN
|| !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (cast)))
return false;
/* Result of the cast stmt is the argument to the builtin. */
if (arg != gimple_assign_lhs (cast))
return false;
arg = gimple_assign_rhs1 (cast);
}
gcond *cond = dyn_cast <gcond *> (*gsi_last_bb (cond_bb));
/* Cond_bb has a check for b_4 [!=|==] 0 before calling the popcount/clz/ctz
builtin. */
if (!cond
|| (gimple_cond_code (cond) != NE_EXPR
&& gimple_cond_code (cond) != EQ_EXPR)
|| !integer_zerop (gimple_cond_rhs (cond))
|| arg != gimple_cond_lhs (cond))
return false;
/* Canonicalize. */
if ((e2->flags & EDGE_TRUE_VALUE
&& gimple_cond_code (cond) == NE_EXPR)
|| (e1->flags & EDGE_TRUE_VALUE
&& gimple_cond_code (cond) == EQ_EXPR))
{
std::swap (arg0, arg1);
std::swap (e1, e2);
}
/* Check PHI arguments. */
if (lhs != arg0
|| TREE_CODE (arg1) != INTEGER_CST)
return false;
if (any_val)
{
if (!tree_fits_shwi_p (arg1))
return false;
HOST_WIDE_INT at_zero = tree_to_shwi (arg1);
if ((int) at_zero != at_zero)
return false;
val = at_zero;
}
else if (wi::to_wide (arg1) != val)
return false;
/* And insert the popcount/clz/ctz builtin and cast stmt before the
cond_bb. */
gsi = gsi_last_bb (cond_bb);
if (cast)
{
gsi_from = gsi_for_stmt (cast);
gsi_move_before (&gsi_from, &gsi);
reset_flow_sensitive_info (gimple_get_lhs (cast));
}
gsi_from = gsi_for_stmt (call);
if (ifn == IFN_LAST
|| (gimple_call_internal_p (call) && gimple_call_num_args (call) == 2))
gsi_move_before (&gsi_from, &gsi);
else
{
/* For __builtin_c[lt]z* force .C[LT]Z ifn, because only
the latter is well defined at zero. */
call = gimple_build_call_internal (ifn, 2, gimple_call_arg (call, 0),
build_int_cst (integer_type_node, val));
gimple_call_set_lhs (call, lhs);
gsi_insert_before (&gsi, call, GSI_SAME_STMT);
gsi_remove (&gsi_from, true);
}
reset_flow_sensitive_info (lhs);
/* Now update the PHI and remove unneeded bbs. */
replace_phi_edge_with_variable (cond_bb, e2, phi, lhs);
return true;
}
/* Auxiliary functions to determine the set of memory accesses which
can't trap because they are preceded by accesses to the same memory
portion. We do that for MEM_REFs, so we only need to track
the SSA_NAME of the pointer indirectly referenced. The algorithm
simply is a walk over all instructions in dominator order. When
we see an MEM_REF we determine if we've already seen a same
ref anywhere up to the root of the dominator tree. If we do the
current access can't trap. If we don't see any dominating access
the current access might trap, but might also make later accesses
non-trapping, so we remember it. We need to be careful with loads
or stores, for instance a load might not trap, while a store would,
so if we see a dominating read access this doesn't mean that a later
write access would not trap. Hence we also need to differentiate the
type of access(es) seen.
??? We currently are very conservative and assume that a load might
trap even if a store doesn't (write-only memory). This probably is
overly conservative.
We currently support a special case that for !TREE_ADDRESSABLE automatic
variables, it could ignore whether something is a load or store because the
local stack should be always writable. */
/* A hash-table of references (MEM_REF/ARRAY_REF/COMPONENT_REF), and in which
basic block an *_REF through it was seen, which would constitute a
no-trap region for same accesses.
Size is needed to support 2 MEM_REFs of different types, like
MEM<double>(s_1) and MEM<long>(s_1), which would compare equal with
OEP_ADDRESS_OF. */
struct ref_to_bb
{
tree exp;
HOST_WIDE_INT size;
unsigned int phase;
basic_block bb;
};
/* Hashtable helpers. */
struct refs_hasher : free_ptr_hash<ref_to_bb>
{
static inline hashval_t hash (const ref_to_bb *);
static inline bool equal (const ref_to_bb *, const ref_to_bb *);
};
/* Used for quick clearing of the hash-table when we see calls.
Hash entries with phase < nt_call_phase are invalid. */
static unsigned int nt_call_phase;
/* The hash function. */
inline hashval_t
refs_hasher::hash (const ref_to_bb *n)
{
inchash::hash hstate;
inchash::add_expr (n->exp, hstate, OEP_ADDRESS_OF);
hstate.add_hwi (n->size);
return hstate.end ();
}
/* The equality function of *P1 and *P2. */
inline bool
refs_hasher::equal (const ref_to_bb *n1, const ref_to_bb *n2)
{
return operand_equal_p (n1->exp, n2->exp, OEP_ADDRESS_OF)
&& n1->size == n2->size;
}
class nontrapping_dom_walker : public dom_walker
{
public:
nontrapping_dom_walker (cdi_direction direction, hash_set<tree> *ps)
: dom_walker (direction), m_nontrapping (ps), m_seen_refs (128)
{}
edge before_dom_children (basic_block) final override;
void after_dom_children (basic_block) final override;
private:
/* We see the expression EXP in basic block BB. If it's an interesting
expression (an MEM_REF through an SSA_NAME) possibly insert the
expression into the set NONTRAP or the hash table of seen expressions.
STORE is true if this expression is on the LHS, otherwise it's on
the RHS. */
void add_or_mark_expr (basic_block, tree, bool);
hash_set<tree> *m_nontrapping;
/* The hash table for remembering what we've seen. */
hash_table<refs_hasher> m_seen_refs;
};
/* Called by walk_dominator_tree, when entering the block BB. */
edge
nontrapping_dom_walker::before_dom_children (basic_block bb)
{
edge e;
edge_iterator ei;
gimple_stmt_iterator gsi;
/* If we haven't seen all our predecessors, clear the hash-table. */
FOR_EACH_EDGE (e, ei, bb->preds)
if ((((size_t)e->src->aux) & 2) == 0)
{
nt_call_phase++;
break;
}
/* Mark this BB as being on the path to dominator root and as visited. */
bb->aux = (void*)(1 | 2);
/* And walk the statements in order. */
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple *stmt = gsi_stmt (gsi);
if ((gimple_code (stmt) == GIMPLE_ASM && gimple_vdef (stmt))
|| (is_gimple_call (stmt)
&& (!nonfreeing_call_p (stmt) || !nonbarrier_call_p (stmt))))
nt_call_phase++;
else if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt))
{
add_or_mark_expr (bb, gimple_assign_lhs (stmt), true);
add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), false);
}
}
return NULL;
}
/* Called by walk_dominator_tree, when basic block BB is exited. */
void
nontrapping_dom_walker::after_dom_children (basic_block bb)
{
/* This BB isn't on the path to dominator root anymore. */
bb->aux = (void*)2;
}
/* We see the expression EXP in basic block BB. If it's an interesting
expression of:
1) MEM_REF
2) ARRAY_REF
3) COMPONENT_REF
possibly insert the expression into the set NONTRAP or the hash table
of seen expressions. STORE is true if this expression is on the LHS,
otherwise it's on the RHS. */
void
nontrapping_dom_walker::add_or_mark_expr (basic_block bb, tree exp, bool store)
{
HOST_WIDE_INT size;
if ((TREE_CODE (exp) == MEM_REF || TREE_CODE (exp) == ARRAY_REF
|| TREE_CODE (exp) == COMPONENT_REF)
&& (size = int_size_in_bytes (TREE_TYPE (exp))) > 0)
{
struct ref_to_bb map;
ref_to_bb **slot;
struct ref_to_bb *r2bb;
basic_block found_bb = 0;
if (!store)
{
tree base = get_base_address (exp);
/* Only record a LOAD of a local variable without address-taken, as
the local stack is always writable. This allows cselim on a STORE
with a dominating LOAD. */
if (!auto_var_p (base) || TREE_ADDRESSABLE (base))
return;
}
/* Try to find the last seen *_REF, which can trap. */
map.exp = exp;
map.size = size;
slot = m_seen_refs.find_slot (&map, INSERT);
r2bb = *slot;
if (r2bb && r2bb->phase >= nt_call_phase)
found_bb = r2bb->bb;
/* If we've found a trapping *_REF, _and_ it dominates EXP
(it's in a basic block on the path from us to the dominator root)
then we can't trap. */
if (found_bb && (((size_t)found_bb->aux) & 1) == 1)
{
m_nontrapping->add (exp);
}
else
{
/* EXP might trap, so insert it into the hash table. */
if (r2bb)
{
r2bb->phase = nt_call_phase;
r2bb->bb = bb;
}
else
{
r2bb = XNEW (struct ref_to_bb);
r2bb->phase = nt_call_phase;
r2bb->bb = bb;
r2bb->exp = exp;
r2bb->size = size;
*slot = r2bb;
}
}
}
}
/* This is the entry point of gathering non trapping memory accesses.
It will do a dominator walk over the whole function, and it will
make use of the bb->aux pointers. It returns a set of trees
(the MEM_REFs itself) which can't trap. */
static hash_set<tree> *
get_non_trapping (void)
{
nt_call_phase = 0;
hash_set<tree> *nontrap = new hash_set<tree>;
nontrapping_dom_walker (CDI_DOMINATORS, nontrap)
.walk (cfun->cfg->x_entry_block_ptr);
clear_aux_for_blocks ();
return nontrap;
}
/* Do the main work of conditional store replacement. We already know
that the recognized pattern looks like so:
split:
if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
MIDDLE_BB:
something
fallthrough (edge E0)
JOIN_BB:
some more
We check that MIDDLE_BB contains only one store, that that store
doesn't trap (not via NOTRAP, but via checking if an access to the same
memory location dominates us, or the store is to a local addressable
object) and that the store has a "simple" RHS. */
static bool
cond_store_replacement (basic_block middle_bb, basic_block join_bb,
edge e0, edge e1, hash_set<tree> *nontrap)
{
gimple *assign = last_and_only_stmt (middle_bb);
tree lhs, rhs, name, name2;
gphi *newphi;
gassign *new_stmt;
gimple_stmt_iterator gsi;
location_t locus;
/* Check if middle_bb contains of only one store. */
if (!assign
|| !gimple_assign_single_p (assign)
|| gimple_has_volatile_ops (assign))
return false;
/* And no PHI nodes so all uses in the single stmt are also
available where we insert to. */
if (!gimple_seq_empty_p (phi_nodes (middle_bb)))
return false;
locus = gimple_location (assign);
lhs = gimple_assign_lhs (assign);
rhs = gimple_assign_rhs1 (assign);
if ((!REFERENCE_CLASS_P (lhs)
&& !DECL_P (lhs))
|| !is_gimple_reg_type (TREE_TYPE (lhs)))
return false;
/* Prove that we can move the store down. We could also check
TREE_THIS_NOTRAP here, but in that case we also could move stores,
whose value is not available readily, which we want to avoid. */
if (!nontrap->contains (lhs))
{
/* If LHS is an access to a local variable without address-taken
(or when we allow data races) and known not to trap, we could
always safely move down the store. */
tree base;
if (ref_can_have_store_data_races (lhs)
|| tree_could_trap_p (lhs)
/* tree_could_trap_p is a predicate for rvalues, so check
for readonly memory explicitly. */
|| ((base = get_base_address (lhs))
&& ((DECL_P (base)
&& TREE_READONLY (base))
|| TREE_CODE (base) == STRING_CST)))
return false;
}
/* Now we've checked the constraints, so do the transformation:
1) Remove the single store. */
gsi = gsi_for_stmt (assign);
unlink_stmt_vdef (assign);
gsi_remove (&gsi, true);
release_defs (assign);
/* Make both store and load use alias-set zero as we have to
deal with the case of the store being a conditional change
of the dynamic type. */
lhs = unshare_expr (lhs);
tree *basep = &lhs;
while (handled_component_p (*basep))
basep = &TREE_OPERAND (*basep, 0);
if (TREE_CODE (*basep) == MEM_REF
|| TREE_CODE (*basep) == TARGET_MEM_REF)
TREE_OPERAND (*basep, 1)
= fold_convert (ptr_type_node, TREE_OPERAND (*basep, 1));
else
*basep = build2 (MEM_REF, TREE_TYPE (*basep),
build_fold_addr_expr (*basep),
build_zero_cst (ptr_type_node));
/* 2) Insert a load from the memory of the store to the temporary
on the edge which did not contain the store. */
name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
new_stmt = gimple_build_assign (name, lhs);
gimple_set_location (new_stmt, locus);
lhs = unshare_expr (lhs);
{
/* Set the no-warning bit on the rhs of the load to avoid uninit
warnings. */
tree rhs1 = gimple_assign_rhs1 (new_stmt);
suppress_warning (rhs1, OPT_Wuninitialized);
}
gsi_insert_on_edge (e1, new_stmt);
/* 3) Create a PHI node at the join block, with one argument
holding the old RHS, and the other holding the temporary
where we stored the old memory contents. */
name2 = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
newphi = create_phi_node (name2, join_bb);
add_phi_arg (newphi, rhs, e0, locus);
add_phi_arg (newphi, name, e1, locus);
new_stmt = gimple_build_assign (lhs, gimple_phi_result (newphi));
/* 4) Insert that PHI node. */
gsi = gsi_after_labels (join_bb);
if (gsi_end_p (gsi))
{
gsi = gsi_last_bb (join_bb);
gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
}
else
gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nConditional store replacement happened!");
fprintf (dump_file, "\nReplaced the store with a load.");
fprintf (dump_file, "\nInserted a new PHI statement in joint block:\n");
print_gimple_stmt (dump_file, new_stmt, 0, TDF_VOPS|TDF_MEMSYMS);
}
statistics_counter_event (cfun, "conditional store replacement", 1);
return true;
}
/* Do the main work of conditional store replacement. */
static bool
cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb,
basic_block join_bb, gimple *then_assign,
gimple *else_assign,
gphi *vphi)
{
tree lhs_base, lhs, then_rhs, else_rhs, name;
location_t then_locus, else_locus;
gimple_stmt_iterator gsi;
gphi *newphi = nullptr;
gassign *new_stmt;
if (then_assign == NULL
|| !gimple_assign_single_p (then_assign)
|| else_assign == NULL
|| !gimple_assign_single_p (else_assign)
|| stmt_references_abnormal_ssa_name (then_assign)
|| stmt_references_abnormal_ssa_name (else_assign))
return false;
/* Allow both being clobbers but no other volatile operations. */
if (gimple_clobber_p (then_assign)
&& gimple_clobber_p (else_assign))
;
else if (gimple_has_volatile_ops (then_assign)
|| gimple_has_volatile_ops (else_assign))
return false;
lhs = gimple_assign_lhs (then_assign);
if (!operand_equal_p (lhs, gimple_assign_lhs (else_assign), 0))
return false;
lhs_base = get_base_address (lhs);
if (lhs_base == NULL_TREE
|| (!DECL_P (lhs_base) && TREE_CODE (lhs_base) != MEM_REF))
return false;
then_rhs = gimple_assign_rhs1 (then_assign);
else_rhs = gimple_assign_rhs1 (else_assign);
then_locus = gimple_location (then_assign);
else_locus = gimple_location (else_assign);
if (!is_gimple_reg_type (TREE_TYPE (lhs)))
{
/* Handle clobbers seperately as operand_equal_p does not check
the kind of the clobbers being the same. */
if (TREE_CLOBBER_P (then_rhs) && TREE_CLOBBER_P (else_rhs))
{
if (CLOBBER_KIND (then_rhs) != CLOBBER_KIND (else_rhs))
return false;
}
else if (!operand_equal_p (then_rhs, else_rhs))
return false;
/* Currently only handle commoning of `= {}`. */
if (TREE_CODE (then_rhs) != CONSTRUCTOR)
return false;
}
if (dump_file && (dump_flags & TDF_DETAILS))
{
if (TREE_CLOBBER_P (then_rhs))
fprintf(dump_file, "factoring out clobber:\n\tthen:\n");
else
fprintf(dump_file, "factoring out stores:\n\tthen:\n");
print_gimple_stmt (dump_file, then_assign, 0,
TDF_VOPS|TDF_MEMSYMS);
fprintf(dump_file, "\telse:\n");
print_gimple_stmt (dump_file, else_assign, 0,
TDF_VOPS|TDF_MEMSYMS);
fprintf (dump_file, "\n");
}
/* Now we've checked the constraints, so do the transformation:
1) Remove the stores. */
gsi = gsi_for_stmt (then_assign);
unlink_stmt_vdef (then_assign);
gsi_remove (&gsi, true);
release_defs (then_assign);
gsi = gsi_for_stmt (else_assign);
unlink_stmt_vdef (else_assign);
gsi_remove (&gsi, true);
release_defs (else_assign);
/* 2) Create a PHI node at the join block, with one argument
holding the old RHS, and the other holding the temporary
where we stored the old memory contents. */
if (operand_equal_p (then_rhs, else_rhs))
name = then_rhs;
else
{
name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
newphi = create_phi_node (name, join_bb);
add_phi_arg (newphi, then_rhs, EDGE_SUCC (then_bb, 0), then_locus);
add_phi_arg (newphi, else_rhs, EDGE_SUCC (else_bb, 0), else_locus);
}
new_stmt = gimple_build_assign (lhs, name);
/* Update the vdef for the new store statement. */
tree newvphilhs = make_ssa_name (gimple_vop (cfun));
tree vdef = gimple_phi_result (vphi);
gimple_set_vuse (new_stmt, newvphilhs);
gimple_set_vdef (new_stmt, vdef);
gimple_phi_set_result (vphi, newvphilhs);
SSA_NAME_DEF_STMT (vdef) = new_stmt;
update_stmt (vphi);
if (dump_file && (dump_flags & TDF_DETAILS))
{
if (newphi)
{
fprintf(dump_file, "to use phi:\n");
print_gimple_stmt (dump_file, newphi, 0,
TDF_VOPS|TDF_MEMSYMS);
fprintf(dump_file, "\n");
}
else
fprintf(dump_file, "to:\n");
print_gimple_stmt (dump_file, new_stmt, 0,
TDF_VOPS|TDF_MEMSYMS);
fprintf(dump_file, "\n\n");
}
/* 3) Insert that new store. */
gsi = gsi_after_labels (join_bb);
if (gsi_end_p (gsi))
{
gsi = gsi_last_bb (join_bb);
gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
}
else
gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
statistics_counter_event (cfun, "if-then-else store replacement", 1);
return true;
}
/* Return the last store in BB with VDEF or NULL if there are
loads following the store. VPHI is where the only use of the
vdef should be. If ONLYONESTORE is true, then the store is
the only store in the BB. */
static gimple *
trailing_store_in_bb (basic_block bb, tree vdef, gphi *vphi, bool onlyonestore)
{
if (SSA_NAME_IS_DEFAULT_DEF (vdef))
return NULL;
gimple *store = SSA_NAME_DEF_STMT (vdef);
if (gimple_bb (store) != bb
|| gimple_code (store) == GIMPLE_PHI)
return NULL;
/* Verify there is no other store in this BB if requested. */
if (onlyonestore
&& !SSA_NAME_IS_DEFAULT_DEF (gimple_vuse (store))
&& gimple_bb (SSA_NAME_DEF_STMT (gimple_vuse (store))) == bb
&& gimple_code (SSA_NAME_DEF_STMT (gimple_vuse (store))) != GIMPLE_PHI)
return NULL;
/* Verify there is no load or store after the store, the vdef of the store
should only be used by the vphi joining the 2 bbs. */
use_operand_p use_p;
gimple *use_stmt;
if (!single_imm_use (gimple_vdef (store), &use_p, &use_stmt))
return NULL;
if (use_stmt != vphi)
return NULL;
return store;
}
/* Limited Conditional store replacement. We already know
that the recognized pattern looks like so:
split:
if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
THEN_BB:
...
STORE = Y;
...
goto JOIN_BB;
ELSE_BB:
...
STORE = Z;
...
fallthrough (edge E0)
JOIN_BB:
some more
Handles only the case with store in THEN_BB and ELSE_BB. That is
cheap enough due to in phiopt and not worry about heurstics. Moving the store
out might provide an opportunity for a phiopt to happen.
At -O1 (!flag_expensive_optimizations), this only handles the only store in
the BBs. */
static bool
cond_if_else_store_replacement_limited (basic_block then_bb, basic_block else_bb,
basic_block join_bb)
{
gphi *vphi = get_virtual_phi (join_bb);
if (!vphi)
return false;
tree then_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (then_bb));
gimple *then_assign = trailing_store_in_bb (then_bb, then_vdef, vphi,
!flag_expensive_optimizations);
if (!then_assign)
return false;
tree else_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (else_bb));
gimple *else_assign = trailing_store_in_bb (else_bb, else_vdef, vphi,
!flag_expensive_optimizations);
if (!else_assign)
return false;
return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
then_assign, else_assign, vphi);
}
/* Conditional store replacement. We already know
that the recognized pattern looks like so:
split:
if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
THEN_BB:
...
X = Y;
...
goto JOIN_BB;
ELSE_BB:
...
X = Z;
...
fallthrough (edge E0)
JOIN_BB:
some more
We check that it is safe to sink the store to JOIN_BB by verifying that
there are no read-after-write or write-after-write dependencies in
THEN_BB and ELSE_BB. */
static bool
cond_if_else_store_replacement (basic_block then_bb, basic_block else_bb,
basic_block join_bb)
{
vec<data_reference_p> then_datarefs, else_datarefs;
vec<ddr_p> then_ddrs, else_ddrs;
gimple *then_store, *else_store;
bool found, ok = false, res;
tree then_lhs, else_lhs;
basic_block blocks[3];
gphi *vphi = get_virtual_phi (join_bb);
if (!vphi)
return false;
/* Handle the case with trailing stores in THEN_BB and ELSE_BB. That is
cheap enough to always handle as it allows us to elide dependence
checking. */
while (cond_if_else_store_replacement_limited (then_bb, else_bb, join_bb))
;
/* If either vectorization or if-conversion is disabled then do
not sink any stores. */
if (param_max_stores_to_sink == 0
|| (!flag_tree_loop_vectorize && !flag_tree_slp_vectorize)
|| !flag_tree_loop_if_convert)
return false;
/* Find data references. */
then_datarefs.create (1);
else_datarefs.create (1);
if ((find_data_references_in_bb (NULL, then_bb, &then_datarefs)
== chrec_dont_know)
|| !then_datarefs.length ()
|| (find_data_references_in_bb (NULL, else_bb, &else_datarefs)
== chrec_dont_know)
|| !else_datarefs.length ())
{
free_data_refs (then_datarefs);
free_data_refs (else_datarefs);
return false;
}
/* Find pairs of stores with equal LHS. */
auto_vec<std::pair<gimple *, gimple *>, 1> stores_pairs;
for (auto then_dr : then_datarefs)
{
if (DR_IS_READ (then_dr))
continue;
then_store = DR_STMT (then_dr);
then_lhs = gimple_get_lhs (then_store);
if (then_lhs == NULL_TREE)
continue;
found = false;
for (auto else_dr : else_datarefs)
{
if (DR_IS_READ (else_dr))
continue;
else_store = DR_STMT (else_dr);
else_lhs = gimple_get_lhs (else_store);
if (else_lhs == NULL_TREE)
continue;
if (operand_equal_p (then_lhs, else_lhs, 0))
{
found = true;
break;
}
}
if (!found)
continue;
stores_pairs.safe_push (std::make_pair (then_store, else_store));
}
/* No pairs of stores found. */
if (!stores_pairs.length ()
|| stores_pairs.length () > (unsigned) param_max_stores_to_sink)
{
free_data_refs (then_datarefs);
free_data_refs (else_datarefs);
return false;
}
/* Compute and check data dependencies in both basic blocks. */
then_ddrs.create (1);
else_ddrs.create (1);
if (!compute_all_dependences (then_datarefs, &then_ddrs,
vNULL, false)
|| !compute_all_dependences (else_datarefs, &else_ddrs,
vNULL, false))
{
free_dependence_relations (then_ddrs);
free_dependence_relations (else_ddrs);
free_data_refs (then_datarefs);
free_data_refs (else_datarefs);
return false;
}
blocks[0] = then_bb;
blocks[1] = else_bb;
blocks[2] = join_bb;
renumber_gimple_stmt_uids_in_blocks (blocks, 3);
/* Check that there are no read-after-write or write-after-write dependencies
in THEN_BB. */
for (auto ddr : then_ddrs)
{
struct data_reference *dra = DDR_A (ddr);
struct data_reference *drb = DDR_B (ddr);
if (DDR_ARE_DEPENDENT (ddr) != chrec_known
&& ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
&& gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
|| (DR_IS_READ (drb) && DR_IS_WRITE (dra)
&& gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
|| (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
{
free_dependence_relations (then_ddrs);
free_dependence_relations (else_ddrs);
free_data_refs (then_datarefs);
free_data_refs (else_datarefs);
return false;
}
}
/* Check that there are no read-after-write or write-after-write dependencies
in ELSE_BB. */
for (auto ddr : else_ddrs)
{
struct data_reference *dra = DDR_A (ddr);
struct data_reference *drb = DDR_B (ddr);
if (DDR_ARE_DEPENDENT (ddr) != chrec_known
&& ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
&& gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
|| (DR_IS_READ (drb) && DR_IS_WRITE (dra)
&& gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
|| (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
{
free_dependence_relations (then_ddrs);
free_dependence_relations (else_ddrs);
free_data_refs (then_datarefs);
free_data_refs (else_datarefs);
return false;
}
}
/* Sink stores with same LHS. */
for (auto &store_pair : stores_pairs)
{
then_store = store_pair.first;
else_store = store_pair.second;
res = cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
then_store, else_store, vphi);
ok = ok || res;
}
free_dependence_relations (then_ddrs);
free_dependence_relations (else_ddrs);
free_data_refs (then_datarefs);
free_data_refs (else_datarefs);
return ok;
}
/* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */
static bool
local_mem_dependence (gimple *stmt, basic_block bb)
{
tree vuse = gimple_vuse (stmt);
gimple *def;
if (!vuse)
return false;
def = SSA_NAME_DEF_STMT (vuse);
return (def && gimple_bb (def) == bb);
}
/* Given a "diamond" control-flow pattern where BB0 tests a condition,
BB1 and BB2 are "then" and "else" blocks dependent on this test,
and BB3 rejoins control flow following BB1 and BB2, look for
opportunities to hoist loads as follows. If BB3 contains a PHI of
two loads, one each occurring in BB1 and BB2, and the loads are
provably of adjacent fields in the same structure, then move both
loads into BB0. Of course this can only be done if there are no
dependencies preventing such motion.
One of the hoisted loads will always be speculative, so the
transformation is currently conservative:
- The fields must be strictly adjacent.
- The two fields must occupy a single memory block that is
guaranteed to not cross a page boundary.
The last is difficult to prove, as such memory blocks should be
aligned on the minimum of the stack alignment boundary and the
alignment guaranteed by heap allocation interfaces. Thus we rely
on a parameter for the alignment value.
Provided a good value is used for the last case, the first
restriction could possibly be relaxed. */
static void
hoist_adjacent_loads (basic_block bb0, basic_block bb1,
basic_block bb2, basic_block bb3)
{
unsigned HOST_WIDE_INT param_align = param_l1_cache_line_size;
unsigned HOST_WIDE_INT param_align_bits = param_align * BITS_PER_UNIT;
gphi_iterator gsi;
/* Walk the phis in bb3 looking for an opportunity. We are looking
for phis of two SSA names, one each of which is defined in bb1 and
bb2. */
for (gsi = gsi_start_phis (bb3); !gsi_end_p (gsi); gsi_next (&gsi))
{
gphi *phi_stmt = gsi.phi ();
gimple *def1, *def2;
tree arg1, arg2, ref1, ref2, field1, field2;
tree tree_offset1, tree_offset2, tree_size2, next;
unsigned HOST_WIDE_INT offset1, offset2, size2, align1;
gimple_stmt_iterator gsi2;
basic_block bb_for_def1, bb_for_def2;
if (gimple_phi_num_args (phi_stmt) != 2
|| virtual_operand_p (gimple_phi_result (phi_stmt)))
continue;
arg1 = gimple_phi_arg_def (phi_stmt, 0);
arg2 = gimple_phi_arg_def (phi_stmt, 1);
if (TREE_CODE (arg1) != SSA_NAME
|| TREE_CODE (arg2) != SSA_NAME
|| SSA_NAME_IS_DEFAULT_DEF (arg1)
|| SSA_NAME_IS_DEFAULT_DEF (arg2))
continue;
def1 = SSA_NAME_DEF_STMT (arg1);
def2 = SSA_NAME_DEF_STMT (arg2);
if ((gimple_bb (def1) != bb1 || gimple_bb (def2) != bb2)
&& (gimple_bb (def2) != bb1 || gimple_bb (def1) != bb2))
continue;
/* Check the mode of the arguments to be sure a conditional move
can be generated for it. */
if (optab_handler (movcc_optab, TYPE_MODE (TREE_TYPE (arg1)))
== CODE_FOR_nothing)
continue;
/* Both statements must be assignments whose RHS is a COMPONENT_REF. */
if (!gimple_assign_single_p (def1)
|| !gimple_assign_single_p (def2)
|| gimple_has_volatile_ops (def1)
|| gimple_has_volatile_ops (def2))
continue;
ref1 = gimple_assign_rhs1 (def1);
ref2 = gimple_assign_rhs1 (def2);
if (TREE_CODE (ref1) != COMPONENT_REF
|| TREE_CODE (ref2) != COMPONENT_REF)
continue;
/* The zeroth operand of the two component references must be
identical. It is not sufficient to compare get_base_address of
the two references, because this could allow for different
elements of the same array in the two trees. It is not safe to
assume that the existence of one array element implies the
existence of a different one. */
if (!operand_equal_p (TREE_OPERAND (ref1, 0), TREE_OPERAND (ref2, 0), 0))
continue;
field1 = TREE_OPERAND (ref1, 1);
field2 = TREE_OPERAND (ref2, 1);
/* Check for field adjacency, and ensure field1 comes first. */
for (next = DECL_CHAIN (field1);
next && TREE_CODE (next) != FIELD_DECL;
next = DECL_CHAIN (next))
;
if (next != field2)
{
for (next = DECL_CHAIN (field2);
next && TREE_CODE (next) != FIELD_DECL;
next = DECL_CHAIN (next))
;
if (next != field1)
continue;
std::swap (field1, field2);
std::swap (def1, def2);
}
bb_for_def1 = gimple_bb (def1);
bb_for_def2 = gimple_bb (def2);
/* Check for proper alignment of the first field. */
tree_offset1 = bit_position (field1);
tree_offset2 = bit_position (field2);
tree_size2 = DECL_SIZE (field2);
if (!tree_fits_uhwi_p (tree_offset1)
|| !tree_fits_uhwi_p (tree_offset2)
|| !tree_fits_uhwi_p (tree_size2))
continue;
offset1 = tree_to_uhwi (tree_offset1);
offset2 = tree_to_uhwi (tree_offset2);
size2 = tree_to_uhwi (tree_size2);
align1 = DECL_ALIGN (field1) % param_align_bits;
if (offset1 % BITS_PER_UNIT != 0)
continue;
/* For profitability, the two field references should fit within
a single cache line. */
if (align1 + offset2 - offset1 + size2 > param_align_bits)
continue;
/* The two expressions cannot be dependent upon vdefs defined
in bb1/bb2. */
if (local_mem_dependence (def1, bb_for_def1)
|| local_mem_dependence (def2, bb_for_def2))
continue;
/* The conditions are satisfied; hoist the loads from bb1 and bb2 into
bb0. We hoist the first one first so that a cache miss is handled
efficiently regardless of hardware cache-fill policy. */
gsi2 = gsi_for_stmt (def1);
gsi_move_to_bb_end (&gsi2, bb0);
gsi2 = gsi_for_stmt (def2);
gsi_move_to_bb_end (&gsi2, bb0);
statistics_counter_event (cfun, "hoisted loads", 1);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file,
"\nHoisting adjacent loads from %d and %d into %d: \n",
bb_for_def1->index, bb_for_def2->index, bb0->index);
print_gimple_stmt (dump_file, def1, 0, TDF_VOPS|TDF_MEMSYMS);
print_gimple_stmt (dump_file, def2, 0, TDF_VOPS|TDF_MEMSYMS);
}
}
}
/* Determine whether we should attempt to hoist adjacent loads out of
diamond patterns in pass_phiopt. Always hoist loads if
-fhoist-adjacent-loads is specified and the target machine has
both a conditional move instruction and a defined cache line size. */
static bool
gate_hoist_loads (void)
{
return (flag_hoist_adjacent_loads == 1
&& param_l1_cache_line_size
&& HAVE_conditional_move);
}
template <class func_type>
static void
execute_over_cond_phis (func_type func)
{
unsigned n, i;
basic_block *bb_order;
basic_block bb;
/* Search every basic block for COND_EXPR we may be able to optimize.
We walk the blocks in order that guarantees that a block with
a single predecessor is processed before the predecessor.
This ensures that we collapse inner ifs before visiting the
outer ones, and also that we do not try to visit a removed
block. */
bb_order = single_pred_before_succ_order ();
n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS;
for (i = 0; i < n; i++)
{
basic_block bb1, bb2;
edge e1, e2;
bool diamond_p = false;
bb = bb_order[i];
/* Check to see if the last statement is a GIMPLE_COND. */
gcond *cond_stmt = safe_dyn_cast <gcond *> (*gsi_last_bb (bb));
if (!cond_stmt)
continue;
e1 = EDGE_SUCC (bb, 0);
bb1 = e1->dest;
e2 = EDGE_SUCC (bb, 1);
bb2 = e2->dest;
/* We cannot do the optimization on abnormal edges. */
if ((e1->flags & EDGE_ABNORMAL) != 0
|| (e2->flags & EDGE_ABNORMAL) != 0)
continue;
/* If either bb1's succ or bb2 or bb2's succ is non NULL. */
if (EDGE_COUNT (bb1->succs) == 0
|| EDGE_COUNT (bb2->succs) == 0)
continue;
/* Find the bb which is the fall through to the other. */
if (EDGE_SUCC (bb1, 0)->dest == bb2)
;
else if (EDGE_SUCC (bb2, 0)->dest == bb1)
{
std::swap (bb1, bb2);
std::swap (e1, e2);
}
else if (EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest
&& single_succ_p (bb2))
{
diamond_p = true;
e2 = EDGE_SUCC (bb2, 0);
/* Make sure bb2 is just a fall through. */
if ((e2->flags & EDGE_FALLTHRU) == 0)
continue;
}
else
continue;
e1 = EDGE_SUCC (bb1, 0);
/* Make sure that bb1 is just a fall through. */
if (!single_succ_p (bb1)
|| (e1->flags & EDGE_FALLTHRU) == 0)
continue;
func (bb, bb1, bb2, e1, e2, diamond_p, cond_stmt);
}
free (bb_order);
}
/* This pass tries to replaces an if-then-else block with an
assignment. We have different kinds of transformations.
Some of these transformations are also performed by the ifcvt
RTL optimizer.
PHI-OPT using Match-and-simplify infrastructure
-----------------------
The PHI-OPT pass will try to use match-and-simplify infrastructure
(gimple_simplify) to do transformations. This is implemented in
match_simplify_replacement.
The way it works is it replaces:
bb0:
if (cond) goto bb2; else goto bb1;
bb1:
bb2:
x = PHI <a (bb1), b (bb0), ...>;
with a statement if it gets simplified from `cond ? b : a`.
bb0:
x1 = cond ? b : a;
bb2:
x = PHI <a (bb1), x1 (bb0), ...>;
Bb1 might be removed as it becomes unreachable when doing the replacement.
Though bb1 does not have to be considered a forwarding basic block from bb0.
Will try to see if `(!cond) ? a : b` gets simplified (iff !cond simplifies);
this is done not to have an explosion of patterns in match.pd.
Note bb1 does not need to be completely empty, it can contain
one statement which is known not to trap.
It also can handle the case where we have two forwarding bbs (diamond):
bb0:
if (cond) goto bb2; else goto bb1;
bb1: goto bb3;
bb2: goto bb3;
bb3:
x = PHI <a (bb1), b (bb2), ...>;
And that is replaced with a statement if it is simplified
from `cond ? b : a`.
Again bb1 and bb2 does not have to be completely empty but
each can contain one statement which is known not to trap.
But in this case bb1/bb2 can only be forwarding basic blocks.
This fully replaces the old "Conditional Replacement",
"ABS Replacement" and "MIN/MAX Replacement" transformations as they are now
implmeneted in match.pd.
Value Replacement
-----------------
This transformation, implemented in value_replacement, replaces
bb0:
if (a != b) goto bb2; else goto bb1;
bb1:
bb2:
x = PHI <a (bb1), b (bb0), ...>;
with
bb0:
bb2:
x = PHI <b (bb0), ...>;
This opportunity can sometimes occur as a result of other
optimizations.
Another case caught by value replacement looks like this:
bb0:
t1 = a == CONST;
t2 = b > c;
t3 = t1 & t2;
if (t3 != 0) goto bb1; else goto bb2;
bb1:
bb2:
x = PHI (CONST, a)
Gets replaced with:
bb0:
bb2:
t1 = a == CONST;
t2 = b > c;
t3 = t1 & t2;
x = a;
This pass also performs a fifth transformation of a slightly different
flavor.
Factor operations in COND_EXPR
------------------------------
This transformation factors the unary operations out of COND_EXPR with
factor_out_conditional_operation.
For example:
if (a <= CST) goto <bb 3>; else goto <bb 4>;
<bb 3>:
tmp = (int) a;
<bb 4>:
tmp = PHI <tmp, CST>
Into:
if (a <= CST) goto <bb 3>; else goto <bb 4>;
<bb 3>:
<bb 4>:
a = PHI <a, CST>
tmp = (int) a;
Adjacent Load Hoisting
----------------------
This transformation replaces
bb0:
if (...) goto bb2; else goto bb1;
bb1:
x1 = (<expr>).field1;
goto bb3;
bb2:
x2 = (<expr>).field2;
bb3:
# x = PHI <x1, x2>;
with
bb0:
x1 = (<expr>).field1;
x2 = (<expr>).field2;
if (...) goto bb2; else goto bb1;
bb1:
goto bb3;
bb2:
bb3:
# x = PHI <x1, x2>;
The purpose of this transformation is to enable generation of conditional
move instructions such as Intel CMOVE or PowerPC ISEL. Because one of
the loads is speculative, the transformation is restricted to very
specific cases to avoid introducing a page fault. We are looking for
the common idiom:
if (...)
x = y->left;
else
x = y->right;
where left and right are typically adjacent pointers in a tree structure. */
namespace {
const pass_data pass_data_phiopt =
{
GIMPLE_PASS, /* type */
"phiopt", /* name */
OPTGROUP_NONE, /* optinfo_flags */
TV_TREE_PHIOPT, /* tv_id */
( PROP_cfg | PROP_ssa ), /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
0, /* todo_flags_finish */
};
class pass_phiopt : public gimple_opt_pass
{
public:
pass_phiopt (gcc::context *ctxt)
: gimple_opt_pass (pass_data_phiopt, ctxt), early_p (false)
{}
/* opt_pass methods: */
opt_pass * clone () final override { return new pass_phiopt (m_ctxt); }
void set_pass_param (unsigned n, bool param) final override
{
gcc_assert (n == 0);
early_p = param;
}
bool gate (function *) final override { return flag_ssa_phiopt; }
unsigned int execute (function *) final override;
private:
bool early_p;
}; // class pass_phiopt
} // anon namespace
gimple_opt_pass *
make_pass_phiopt (gcc::context *ctxt)
{
return new pass_phiopt (ctxt);
}
unsigned int
pass_phiopt::execute (function *)
{
bool do_hoist_loads = !early_p ? gate_hoist_loads () : false;
bool cfgchanged = false;
calculate_dominance_info (CDI_DOMINATORS);
mark_ssa_maybe_undefs ();
auto phiopt_exec = [&] (basic_block bb, basic_block bb1,
basic_block bb2, edge e1, edge e2,
bool diamond_p, gcond *cond_stmt)
{
if (diamond_p)
{
basic_block bb3 = e1->dest;
if (!single_pred_p (bb1)
|| !single_pred_p (bb2))
return;
if (do_hoist_loads
&& !FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt)))
&& EDGE_COUNT (bb->succs) == 2
&& EDGE_COUNT (bb3->preds) == 2
/* If one edge or the other is dominant, a conditional move
is likely to perform worse than the well-predicted branch. */
&& !predictable_edge_p (EDGE_SUCC (bb, 0))
&& !predictable_edge_p (EDGE_SUCC (bb, 1)))
hoist_adjacent_loads (bb, bb1, bb2, bb3);
/* Try to see if there are only store in each side of the if
and try to remove that; don't do this for -Og. */
if (EDGE_COUNT (bb3->preds) == 2 && !optimize_debug)
while (cond_if_else_store_replacement_limited (bb1, bb2, bb3))
;
}
gimple_stmt_iterator gsi;
/* Check that we're looking for nested phis. */
basic_block merge = diamond_p ? EDGE_SUCC (bb2, 0)->dest : bb2;
gimple_seq phis = phi_nodes (merge);
if (gimple_seq_empty_p (phis))
return;
/* Factor out operations from the phi if possible. */
if (single_pred_p (bb1)
&& EDGE_COUNT (merge->preds) == 2
&& !optimize_debug)
{
for (gsi = gsi_start (phis); !gsi_end_p (gsi); )
{
gphi *phi = as_a <gphi *> (gsi_stmt (gsi));
if (factor_out_conditional_operation (e1, e2, merge, phi,
cond_stmt))
{
/* Start over if there was an operation that was factored out because the new phi might have another opportunity. */
phis = phi_nodes (merge);
gsi = gsi_start (phis);
}
else
gsi_next (&gsi);
}
}
/* Value replacement can work with more than one PHI
so try that first. */
if (!early_p && !diamond_p)
for (gsi = gsi_start (phis); !gsi_end_p (gsi); gsi_next (&gsi))
{
gphi *phi = as_a <gphi *> (gsi_stmt (gsi));
tree arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
tree arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1) == 2)
{
cfgchanged = true;
return;
}
}
gphi *phi = single_non_singleton_phi_for_edges (phis, e1, e2);
if (!phi)
return;
tree arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
tree arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
/* Something is wrong if we cannot find the arguments in the PHI
node. */
gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE);
/* Do the replacement of conditional if it can be done. */
if (match_simplify_replacement (bb, bb1, bb2, e1, e2, phi,
arg0, arg1, early_p, diamond_p))
cfgchanged = true;
else if (!early_p
&& !diamond_p
&& single_pred_p (bb1)
&& cond_removal_in_builtin_zero_pattern (bb, bb1, e1, e2,
phi, arg0, arg1))
cfgchanged = true;
else if (single_pred_p (bb1)
&& !diamond_p
&& spaceship_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
cfgchanged = true;
};
execute_over_cond_phis (phiopt_exec);
if (cfgchanged)
return TODO_cleanup_cfg;
return 0;
}
/* This pass tries to transform conditional stores into unconditional
ones, enabling further simplifications with the simpler then and else
blocks. In particular it replaces this:
bb0:
if (cond) goto bb2; else goto bb1;
bb1:
*p = RHS;
bb2:
with
bb0:
if (cond) goto bb1; else goto bb2;
bb1:
condtmp' = *p;
bb2:
condtmp = PHI <RHS, condtmp'>
*p = condtmp;
This transformation can only be done under several constraints,
documented below. It also replaces:
bb0:
if (cond) goto bb2; else goto bb1;
bb1:
*p = RHS1;
goto bb3;
bb2:
*p = RHS2;
bb3:
with
bb0:
if (cond) goto bb3; else goto bb1;
bb1:
bb3:
condtmp = PHI <RHS1, RHS2>
*p = condtmp; */
namespace {
const pass_data pass_data_cselim =
{
GIMPLE_PASS, /* type */
"cselim", /* name */
OPTGROUP_NONE, /* optinfo_flags */
TV_TREE_PHIOPT, /* tv_id */
( PROP_cfg | PROP_ssa ), /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
0, /* todo_flags_finish */
};
class pass_cselim : public gimple_opt_pass
{
public:
pass_cselim (gcc::context *ctxt)
: gimple_opt_pass (pass_data_cselim, ctxt)
{}
/* opt_pass methods: */
bool gate (function *) final override { return flag_tree_cselim; }
unsigned int execute (function *) final override;
}; // class pass_cselim
} // anon namespace
gimple_opt_pass *
make_pass_cselim (gcc::context *ctxt)
{
return new pass_cselim (ctxt);
}
unsigned int
pass_cselim::execute (function *)
{
bool cfgchanged = false;
hash_set<tree> *nontrap = 0;
unsigned todo = 0;
/* ??? We are not interested in loop related info, but the following
will create it, ICEing as we didn't init loops with pre-headers.
An interfacing issue of find_data_references_in_bb. */
loop_optimizer_init (LOOPS_NORMAL);
scev_initialize ();
calculate_dominance_info (CDI_DOMINATORS);
/* Calculate the set of non-trapping memory accesses. */
nontrap = get_non_trapping ();
auto cselim_exec = [&] (basic_block bb, basic_block bb1,
basic_block bb2, edge e1, edge e2,
bool diamond_p, gcond *)
{
if (diamond_p)
{
basic_block bb3 = e1->dest;
/* Only handle sinking of store from 2 bbs only,
The middle bbs don't need to come from the
if always since we are sinking rather than
hoisting. */
if (EDGE_COUNT (bb3->preds) != 2)
return;
if (cond_if_else_store_replacement (bb1, bb2, bb3))
cfgchanged = true;
return;
}
/* Also make sure that bb1 only have one predecessor and that it
is bb. */
if (!single_pred_p (bb1)
|| single_pred (bb1) != bb)
return;
/* bb1 is the middle block, bb2 the join block, bb the split block,
e1 the fallthrough edge from bb1 to bb2. We can't do the
optimization if the join block has more than two predecessors. */
if (EDGE_COUNT (bb2->preds) > 2)
return;
if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
cfgchanged = true;
};
execute_over_cond_phis (cselim_exec);
delete nontrap;
/* If the CFG has changed, we should cleanup the CFG. */
if (cfgchanged)
{
/* In cond-store replacement we have added some loads on edges
and new VOPS (as we moved the store, and created a load). */
gsi_commit_edge_inserts ();
todo = TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
}
scev_finalize ();
loop_optimizer_finalize ();
return todo;
}
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