targethooks: Change SAME_FUNCTION_VERSIONS hook to support checking mergeability

This changes the hook to support checking version mergeability for cases
where the version strings do imply the same version, but are conflicting
in some other way so cannot be merged.

This is a change required for adding priority version support in aarch64.

gcc/ChangeLog:

	* target.def (TARGET_OPTION_SAME_FUNCTION_VERSIONS): Update
	documentation.
	* tree.cc (disjoint_version_decls): Change for new NULL parameter
	to same_function_versions.
	(diagnose_versioned_decls): Update to pass diagnostic location to
	same_function_versions.
	* doc/tm.texi: Regenerate.
	* config/aarch64/aarch64.cc (aarch64_same_function_versions):
	Update hook impl for new arguments.
	* config/riscv/riscv.cc (riscv_same_function_versions): Update
	hook impl for new arguments.
	* config/loongarch/loongarch.cc
	(loongarch_same_function_versions): Likewise
	* hooks.cc (hook_stringslice_stringslice_unreachable): Changed
	to...
	(hook_stringslice_consttree_stringslice_consttree_unreachable):
	...this and add extra arguments.
	* hooks.h (hook_stringslice_stringslice_unreachable): Changed
	to...
	(hook_stringslice_consttree_stringslice_consttree_unreachable):
	and add extra arguments.

gcc/config/aarch64/aarch64.cc

@@ -21670,19 +21670,22 @@ aarch64_get_function_versions_dispatcher (void *decl)
    function.  */
 
 bool
-aarch64_same_function_versions (string_slice str1, string_slice str2)
+aarch64_same_function_versions (string_slice old_str, const_tree,
+				string_slice new_str, const_tree)
 {
   enum aarch_parse_opt_result parse_res;
-  aarch64_fmv_feature_mask feature_mask1;
-  aarch64_fmv_feature_mask feature_mask2;
-  parse_res = aarch64_parse_fmv_features (str1, NULL,
-					  &feature_mask1, NULL);
-  gcc_assert (parse_res == AARCH_PARSE_OK);
-  parse_res = aarch64_parse_fmv_features (str2, NULL,
-					  &feature_mask2, NULL);
+  aarch64_fmv_feature_mask old_feature_mask;
+  aarch64_fmv_feature_mask new_feature_mask;
+
+  parse_res = aarch64_parse_fmv_features (old_str, NULL, &old_feature_mask,
+					  NULL);
   gcc_assert (parse_res == AARCH_PARSE_OK);
 
-  return feature_mask1 == feature_mask2;
+  parse_res = aarch64_parse_fmv_features (new_str, NULL, &new_feature_mask,
+					  NULL);
+  gcc_assert (parse_res == AARCH_PARSE_OK);
+
+  return old_feature_mask == new_feature_mask;
 }
 
 /* Implement TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P.  Use an opt-out

gcc/config/loongarch/loongarch.cc

@@ -12165,7 +12165,8 @@ loongarch_generate_version_dispatcher_body (void *node_p)
    This assumes that FN1 and FN2 have the same signature.  */
 
 bool
-loongarch_option_same_function_versions (string_slice str1, string_slice str2)
+loongarch_option_same_function_versions (string_slice str1, const_tree,
+					 string_slice str2, const_tree)
 {
   loongarch_fmv_feature_mask feature_mask1;
   loongarch_fmv_feature_mask feature_mask2;

gcc/config/riscv/riscv.cc

@@ -14869,7 +14869,8 @@ compare_fmv_features (const struct riscv_feature_bits &mask1,
    version.  */
 
 bool
-riscv_same_function_versions (string_slice v1, string_slice v2)
+riscv_same_function_versions (string_slice v1, const_tree, string_slice v2,
+			      const_tree)
 {
   struct riscv_feature_bits mask1, mask2;
   int prio1, prio2;

gcc/doc/tm.texi

@@ -11028,9 +11028,15 @@ changed via the optimize attribute or pragma, see
 @code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}
 @end deftypefn
 
-@deftypefn {Target Hook} bool TARGET_OPTION_SAME_FUNCTION_VERSIONS (string_slice @var{fn1}, string_slice @var{fn2})
+@deftypefn {Target Hook} bool TARGET_OPTION_SAME_FUNCTION_VERSIONS (string_slice @var{fn1}, const_tree @var{decl1}, string_slice @var{fn2}, const_tree @var{decl2})
 This target hook returns @code{true} if the target/target-version strings
 @var{fn1} and @var{fn2} imply the same function version.
+
+If @var{decl1} and @var{decl2} are non @code{NULL} then @var{fn1} and
+@var{fn2} are from an earlier and a later declaration respectively, and the
+hook diagnoses any version string incompatibility for these decls.
+If the version strings are incompatible and the declarations can not be
+merged, then hook emits an error.
 @end deftypefn
 
 @deftypefn {Target Hook} bool TARGET_OPTION_FUNCTIONS_B_RESOLVABLE_FROM_A (tree @var{decl_a}, tree @var{decl_v}, tree @var{base})

gcc/hooks.cc

@@ -595,7 +595,10 @@ hook_stringslice_locationtptr_true (string_slice, location_t *)
 }
 
 bool
-hook_stringslice_stringslice_unreachable (string_slice, string_slice)
+hook_stringslice_consttree_stringslice_consttree_unreachable (string_slice,
+							      const_tree,
+							      string_slice,
+							      const_tree)
 {
   gcc_unreachable ();
 }

gcc/hooks.h

@@ -139,6 +139,6 @@ extern opt_machine_mode hook_optmode_mode_uhwi_none (machine_mode,
 						     unsigned HOST_WIDE_INT);
 
 extern bool hook_stringslice_locationtptr_true (string_slice, location_t *);
-extern bool hook_stringslice_stringslice_unreachable (string_slice, string_slice);
+extern bool hook_stringslice_consttree_stringslice_consttree_unreachable (string_slice, const_tree, string_slice, const_tree);
 
 #endif

gcc/target.def

@@ -6971,14 +6971,22 @@ changed via the optimize attribute or pragma, see\n\
  void, (void),
  hook_void_void)
 
-/* This function returns true if FN1 and FN2 define the same version of a
-   function.  */
+/* This function returns true if FN1 and FN2 define the same version
+   of a function.
+   If DECL1 and DECL2 is not-null then emit a diagnostic if the versions do
+   imply the same version, but are not mergeable.  */
 DEFHOOK
 (same_function_versions,
  "This target hook returns @code{true} if the target/target-version strings\n\
-@var{fn1} and @var{fn2} imply the same function version.",
- bool, (string_slice fn1, string_slice fn2),
- hook_stringslice_stringslice_unreachable)
+@var{fn1} and @var{fn2} imply the same function version.\n\
+\n\
+If @var{decl1} and @var{decl2} are non @code{NULL} then @var{fn1} and\n\
+@var{fn2} are from an earlier and a later declaration respectively, and the\n\
+hook diagnoses any version string incompatibility for these decls.\n\
+If the version strings are incompatible and the declarations can not be\n\
+merged, then hook emits an error.",
+ bool, (string_slice fn1, const_tree decl1, string_slice fn2, const_tree decl2),
+ hook_stringslice_consttree_stringslice_consttree_unreachable)
 
 /* Checks if we can be certain that function DECL_A could resolve DECL_B.  */
 DEFHOOK

gcc/tree.cc

@@ -15610,7 +15610,8 @@ disjoint_version_decls (tree fn1, tree fn2)
 	      for (string_slice v1 : fn1_versions)
 		{
 		  for (string_slice v2 : fn2_versions)
-		    if (targetm.target_option.same_function_versions (v1, v2))
+		    if (targetm.target_option.same_function_versions
+			  (v1, NULL_TREE, v2, NULL_TREE))
 		      return false;
 		}
 	      return true;
@@ -15628,7 +15629,8 @@ disjoint_version_decls (tree fn1, tree fn2)
 	      if (!v2.is_valid ())
 		v2 = "default";
 	      for (string_slice v1 : fn1_versions)
-		if (targetm.target_option.same_function_versions (v1, v2))
+		if (targetm.target_option.same_function_versions
+		      (v1, NULL_TREE, v2, NULL_TREE))
 		  return false;
 	      return true;
 	    }
@@ -15647,7 +15649,8 @@ disjoint_version_decls (tree fn1, tree fn2)
 	  if (!v2.is_valid ())
 	    v2 = "default";
 
-	  if (targetm.target_option.same_function_versions (v1, v2))
+	  if (targetm.target_option.same_function_versions (v1, NULL_TREE,
+							    v2, NULL_TREE))
 	    return false;
 
 	  return true;
@@ -15695,30 +15698,32 @@ diagnose_versioned_decls (tree old_decl, tree new_decl)
      the two sets of target_clones imply the same set of versions.  */
   if (old_target_clones_attr && new_target_clones_attr)
     {
-      auto_vec<string_slice> fn1_versions = get_clone_versions (old_decl);
-      auto_vec<string_slice> fn2_versions = get_clone_versions (new_decl);
+      auto_vec<string_slice> old_versions = get_clone_versions (old_decl);
+      auto_vec<string_slice> new_versions = get_clone_versions (new_decl);
 
       bool mergeable = true;
 
-      if (fn1_versions.length () != fn2_versions.length ())
+      if (old_versions.length () != new_versions.length ())
 	mergeable = false;
 
       /* Check both inclusion directions.  */
-      for (auto fn1v : fn1_versions)
+      for (auto oldv: old_versions)
 	{
 	  bool matched = false;
-	  for (auto fn2v : fn2_versions)
-	    if (targetm.target_option.same_function_versions (fn1v, fn2v))
+	  for (auto newv: new_versions)
+	    if (targetm.target_option.same_function_versions (oldv, old_decl,
+							      newv, new_decl))
 	      matched = true;
 	  if (!matched)
 	    mergeable = false;
 	}
 
-      for (auto fn2v : fn2_versions)
+      for (auto newv: new_versions)
 	{
 	  bool matched = false;
-	  for (auto fn1v : fn1_versions)
-	    if (targetm.target_option.same_function_versions (fn1v, fn2v))
+	  for (auto oldv: old_versions)
+	    if (targetm.target_option.same_function_versions (oldv, old_decl,
+							      newv, new_decl))
 	      matched = true;
 	  if (!matched)
 	    mergeable = false;
@@ -15767,9 +15772,9 @@ diagnose_versioned_decls (tree old_decl, tree new_decl)
       return true;
     }
 
-  /* The only remaining case is two target_version annotated decls.  Must
-     be mergeable as otherwise are distinct.  */
-  return false;
+  /* The only remaining case is two target_version annotated decls.  */
+  return !targetm.target_option.same_function_versions
+	    (old_target_attr, old_decl, new_target_attr, new_decl);
 }
 
 void