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fold-const.c (negate_expr_p): Correct/refine condition for transformations.

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* fold-const.c (negate_expr_p) <PLUS_EXPR, MINUS_EXPR>: Correct/refine
	condition for transformations.  Use !HONOR_SIGN_DEPENDENT_ROUNDING
	&& !HONOR_SIGNED_ZEROS instead of flag_unsafe_math_optimizations.
	(fold_negate_expr) <PLUS_EXPR, MINUS_EXPR>: Likewise.

From-SVN: r118744
This commit is contained in:
Roger Sayle 2006-11-13 02:55:22 +00:00 • committed by Roger Sayle
parent 163b858186
commit 1b43b96773
2 changed files with 15 additions and 4 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-11-12 Roger Sayle <roger@eyesopen.com>
* fold-const.c (negate_expr_p) <PLUS_EXPR, MINUS_EXPR>: Correct/refine
condition for transformations. Use !HONOR_SIGN_DEPENDENT_ROUNDING
&& !HONOR_SIGNED_ZEROS instead of flag_unsafe_math_optimizations.
(fold_negate_expr) <PLUS_EXPR, MINUS_EXPR>: Likewise.
2006-11-12 Daniel Berlin <dberlin@dberlin.org>
Fix PR tree-optimization/29587

12
gcc/fold-const.c
View file

@ -981,7 +981,8 @@ negate_expr_p (tree t)
&& negate_expr_p (TREE_IMAGPART (t));
case PLUS_EXPR:
if (FLOAT_TYPE_P (type) && !flag_unsafe_math_optimizations)
if (HONOR_SIGN_DEPENDENT_ROUNDING (TYPE_MODE (type))
|| HONOR_SIGNED_ZEROS (TYPE_MODE (type)))
return false;
/* -(A + B) -> (-B) - A. */
if (negate_expr_p (TREE_OPERAND (t, 1))
@ -993,7 +994,8 @@ negate_expr_p (tree t)
case MINUS_EXPR:
/* We can't turn -(A-B) into B-A when we honor signed zeros. */
return (! FLOAT_TYPE_P (type) || flag_unsafe_math_optimizations)
return !HONOR_SIGN_DEPENDENT_ROUNDING (TYPE_MODE (type))
&& !HONOR_SIGNED_ZEROS (TYPE_MODE (type))
&& reorder_operands_p (TREE_OPERAND (t, 0),
TREE_OPERAND (t, 1));
@ -1105,7 +1107,8 @@ fold_negate_expr (tree t)
return TREE_OPERAND (t, 0);
case PLUS_EXPR:
if (! FLOAT_TYPE_P (type) || flag_unsafe_math_optimizations)
if (!HONOR_SIGN_DEPENDENT_ROUNDING (TYPE_MODE (type))
&& !HONOR_SIGNED_ZEROS (TYPE_MODE (type)))
{
/* -(A + B) -> (-B) - A. */
if (negate_expr_p (TREE_OPERAND (t, 1))
@ -1129,7 +1132,8 @@ fold_negate_expr (tree t)
case MINUS_EXPR:
/* - (A - B) -> B - A */
if ((! FLOAT_TYPE_P (type) || flag_unsafe_math_optimizations)
if (!HONOR_SIGN_DEPENDENT_ROUNDING (TYPE_MODE (type))
&& !HONOR_SIGNED_ZEROS (TYPE_MODE (type))
&& reorder_operands_p (TREE_OPERAND (t, 0), TREE_OPERAND (t, 1)))
return fold_build2 (MINUS_EXPR, type,
TREE_OPERAND (t, 1), TREE_OPERAND (t, 0));