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re PR middle-end/38751 (odd performance regression with -Os)

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2009-01-07  Richard Guenther  <rguenther@suse.de>

	PR middle-end/38751
	* fold-const.c (extract_muldiv): Remove obsolete comment.
	(fold_plusminus_mult_expr): Undo MINUS_EXPR
	to PLUS_EXPR canonicalization for the canonicalization.

From-SVN: r143152
This commit is contained in:
Richard Guenther 2009-01-07 10:53:30 +00:00 • committed by Richard Biener
parent 238e3a40af
commit cef158f925
2 changed files with 18 additions and 5 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2009-01-07 Richard Guenther <rguenther@suse.de>
PR middle-end/38751
* fold-const.c (extract_muldiv): Remove obsolete comment.
(fold_plusminus_mult_expr): Undo MINUS_EXPR
to PLUS_EXPR canonicalization for the canonicalization.
2009-01-07 Gerald Pfeifer <gerald@pfeifer.com>
* doc/install.texi (alpha*-dec-osf*): Remove note on 32-bit

16
gcc/fold-const.c
View file

@ -6008,10 +6008,6 @@ optimize_minmax_comparison (enum tree_code code, tree type, tree op0, tree op1)
expression would not overflow or that overflow is undefined for the type
in the language in question.
We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
the machine has a multiply-accumulate insn or that this is part of an
addressing calculation.
If we return a non-null expression, it is an equivalent form of the
original computation, but need not be in the original type.
@ -7439,7 +7435,17 @@ fold_plusminus_mult_expr (enum tree_code code, tree type, tree arg0, tree arg1)
else if (TREE_CODE (arg1) == INTEGER_CST)
{
arg10 = build_one_cst (type);
arg11 = arg1;
/* As we canonicalize A - 2 to A + -2 get rid of that sign for
the purpose of this canonicalization. */
if (TREE_INT_CST_HIGH (arg1) == -1
&& negate_expr_p (arg1)
&& code == PLUS_EXPR)
{
arg11 = negate_expr (arg1);
code = MINUS_EXPR;
}
else
arg11 = arg1;
}
else
{