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combine.c (simplify_set): Try harder to find the best CC mode when simplifying a nested COMPARE on the RHS.

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* combine.c (simplify_set): Try harder to find the best CC mode when
	simplifying a nested COMPARE on the RHS.

From-SVN: r171304
This commit is contained in:
Eric Botcazou 2011-03-22 20:04:58 +00:00 committed by Eric Botcazou
parent 56f8587a5b
commit e8b97ccd59
2 changed files with 20 additions and 1 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2011-03-22 Eric Botcazou <ebotcazou@adacore.com>
* combine.c (simplify_set): Try harder to find the best CC mode when
simplifying a nested COMPARE on the RHS.
2011-03-22 Joseph Myers <joseph@codesourcery.com>
* config/alpha/gnu.h: Remove.

14
gcc/combine.c
View File

@ -6240,10 +6240,18 @@ simplify_set (rtx x)
enum rtx_code new_code;
rtx op0, op1, tmp;
int other_changed = 0;
rtx inner_compare = NULL_RTX;
enum machine_mode compare_mode = GET_MODE (dest);
if (GET_CODE (src) == COMPARE)
{
op0 = XEXP (src, 0), op1 = XEXP (src, 1);
if (GET_CODE (op0) == COMPARE && op1 == const0_rtx)
{
inner_compare = op0;
op0 = XEXP (inner_compare, 0), op1 = XEXP (inner_compare, 1);
}
}
else
op0 = src, op1 = CONST0_RTX (GET_MODE (src));
@ -6285,6 +6293,12 @@ simplify_set (rtx x)
need to use a different CC mode here. */
if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC)
compare_mode = GET_MODE (op0);
else if (inner_compare
&& GET_MODE_CLASS (GET_MODE (inner_compare)) == MODE_CC
&& new_code == old_code
&& op0 == XEXP (inner_compare, 0)
&& op1 == XEXP (inner_compare, 1))
compare_mode = GET_MODE (inner_compare);
else
compare_mode = SELECT_CC_MODE (new_code, op0, op1);