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(force_to_mode): Don't allow sign-extension of constants when we are

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narrowing things in an IOR or XOR.

From-SVN: r6117
This commit is contained in:
Richard Kenner
1993-11-19 18:24:20 -05:00
parent 35fc1624ac
commit 2dd484ed8e
1 changed files with 8 additions and 0 deletions
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8
gcc/combine.c
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@@ -5790,6 +5790,14 @@ force_to_mode (x, mode, mask, reg)
op1 = gen_lowpart_for_combine (op_mode, force_to_mode (XEXP (x, 1),
mode, mask, reg));
/* If OP1 is a CONST_INT and X is an IOR or XOR, clear bits outside
MASK since OP1 might have been sign-extended but we never want
to turn on extra bits, since combine might have previously relied
on them being off. */
if (GET_CODE (op1) == CONST_INT && (code == IOR || code == XOR)
&& (INTVAL (op1) & mask) != 0)
op1 = GEN_INT (INTVAL (op1) & mask);
if (op_mode != GET_MODE (x) || op0 != XEXP (x, 0) || op1 != XEXP (x, 1))
x = gen_binary (code, op_mode, op0, op1);
break;