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simplify-rtx.c (simplify_relational_operation_1): Simplify (X^Y) == 0 as X == Y and (X^Y) != 0 as X != Y.

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* simplify-rtx.c (simplify_relational_operation_1):  Simplify
	(X^Y) == 0 as X == Y and (X^Y) != 0 as X != Y.  Simplify (X^Y) == Y
	as X == 0, and some symmetry related transformations.
	Simplify (X^C1) == C2 as X == (C1^C2).  Split long comment line.

From-SVN: r111443
This commit is contained in:
Roger Sayle 2006-02-25 22:29:48 +00:00 • committed by Roger Sayle
parent eb8dffe0fb
commit 5484a3c37c
2 changed files with 40 additions and 1 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-02-25 Roger Sayle <roger@eyesopen.com>
* simplify-rtx.c (simplify_relational_operation_1): Simplify
(X^Y) == 0 as X == Y and (X^Y) != 0 as X != Y. Simplify (X^Y) == Y
as X == 0, and some symmetry related transformations.
Simplify (X^C1) == C2 as X == (C1^C2). Split long comment line.
2006-02-25 Roger Sayle <roger@eyesopen.com>
PR middle-end/23673

34
gcc/simplify-rtx.c
View file

@ -3512,7 +3512,8 @@ simplify_relational_operation_1 (enum rtx_code code, enum machine_mode mode,
{
if (INTVAL (op1) == 0 && COMPARISON_P (op0))
{
/* If op0 is a comparison, extract the comparison arguments form it. */
/* If op0 is a comparison, extract the comparison arguments
from it. */
if (code == NE)
{
if (GET_MODE (op0) == mode)
@ -3561,6 +3562,37 @@ simplify_relational_operation_1 (enum rtx_code code, enum machine_mode mode,
? simplify_gen_unary (ZERO_EXTEND, mode, op0, cmp_mode)
: lowpart_subreg (mode, op0, cmp_mode);
/* (eq/ne (xor x y) 0) simplifies to (eq/ne x y). */
if ((code == EQ || code == NE)
&& op1 == const0_rtx
&& op0code == XOR)
return simplify_gen_relational (code, mode, cmp_mode,
XEXP (op0, 0), XEXP (op0, 1));
/* (eq/ne (xor x y) x) simplifies to (eq/ne x 0). */
if ((code == EQ || code == NE)
&& op0code == XOR
&& rtx_equal_p (XEXP (op0, 0), op1)
&& !side_effects_p (XEXP (op0, 1)))
return simplify_gen_relational (code, mode, cmp_mode, op1, const0_rtx);
/* Likewise (eq/ne (xor x y) y) simplifies to (eq/ne y 0). */
if ((code == EQ || code == NE)
&& op0code == XOR
&& rtx_equal_p (XEXP (op0, 1), op1)
&& !side_effects_p (XEXP (op0, 0)))
return simplify_gen_relational (code, mode, cmp_mode, op1, const0_rtx);
/* (eq/ne (xor x C1) C2) simplifies to (eq/ne x (C1^C2)). */
if ((code == EQ || code == NE)
&& op0code == XOR
&& (GET_CODE (op1) == CONST_INT
|| GET_CODE (op1) == CONST_DOUBLE)
&& (GET_CODE (XEXP (op0, 1)) == CONST_INT
|| GET_CODE (XEXP (op0, 1)) == CONST_DOUBLE))
return simplify_gen_relational (code, mode, cmp_mode, XEXP (op0, 0),
simplify_gen_binary (XOR, cmp_mode,
XEXP (op0, 1), op1));
return NULL_RTX;
}