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re PR tree-optimization/56175 (Issue with combine phase on x86.) 

2013-02-25  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56175
	* tree-ssa-forwprop.c (hoist_conversion_for_bitop_p): New predicate,
	split out from ...
	(simplify_bitwise_binary): ... here.  Also guard the conversion
	of (type) X op CST to (type) (X op ((type-x) CST)) with it.

	* gcc.dg/tree-ssa/forwprop-24.c: New testcase.

From-SVN: r196263
This commit is contained in:
Richard Biener 2013-02-25 15:31:31 +00:00 committed by Richard Biener
parent 5621a5d7b1
commit 259ee451e5
4 changed files with 58 additions and 10 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2013-02-25 Richard Biener <rguenther@suse.de>
PR tree-optimization/56175
* tree-ssa-forwprop.c (hoist_conversion_for_bitop_p): New predicate,
split out from ...
(simplify_bitwise_binary): ... here. Also guard the conversion
of (type) X op CST to (type) (X op ((type-x) CST)) with it.
2013-02-25 Catherine Moore <clm@codesourcery.com>
Revert:

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2013-02-25 Richard Biener <rguenther@suse.de>
PR tree-optimization/56175
* gcc.dg/tree-ssa/forwprop-24.c: New testcase.
2013-02-24 Jakub Jelinek <jakub@redhat.com>
PR c++/56403

18
gcc/testsuite/gcc.dg/tree-ssa/forwprop-24.c Normal file
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@ -0,0 +1,18 @@
/* { dg-do compile } */
/* { dg-options "-O -fdump-tree-cddce1" } */
void bar (void);
unsigned short
foo (unsigned char x, unsigned short y)
{
unsigned char t = (unsigned char)((x & 1) ^ ((unsigned char)y & 1));
if (t == 1)
bar ();
return y;
}
/* We should have combined this to require only one bitwise and
as in (x ^ (char) y) & 1. */
/* { dg-final { scan-tree-dump-times " & " 1 "cddce1" } } */
/* { dg-final { cleanup-tree-dump "cddce1" } } */

37
gcc/tree-ssa-forwprop.c
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@ -1772,6 +1772,29 @@ defcodefor_name (tree name, enum tree_code *code, tree *arg1, tree *arg2)
/* Ignore arg3 currently. */
}
/* Return true if a conversion of an operand from type FROM to type TO
should be applied after performing the operation instead. */
static bool
hoist_conversion_for_bitop_p (tree to, tree from)
{
/* That's a good idea if the conversion widens the operand, thus
after hoisting the conversion the operation will be narrower. */
if (TYPE_PRECISION (from) < TYPE_PRECISION (to))
return true;
/* It's also a good idea if the conversion is to a non-integer mode. */
if (GET_MODE_CLASS (TYPE_MODE (to)) != MODE_INT)
return true;
/* Or if the precision of TO is not the same as the precision
of its mode. */
if (TYPE_PRECISION (to) != GET_MODE_PRECISION (TYPE_MODE (to)))
return true;
return false;
}
/* Simplify bitwise binary operations.
Return true if a transformation applied, otherwise return false. */
@ -1789,9 +1812,11 @@ simplify_bitwise_binary (gimple_stmt_iterator *gsi)
defcodefor_name (arg1, &def1_code, &def1_arg1, &def1_arg2);
defcodefor_name (arg2, &def2_code, &def2_arg1, &def2_arg2);
/* Try to fold (type) X op CST -> (type) (X op ((type-x) CST)). */
/* Try to fold (type) X op CST -> (type) (X op ((type-x) CST))
when profitable. */
if (TREE_CODE (arg2) == INTEGER_CST
&& CONVERT_EXPR_CODE_P (def1_code)
&& hoist_conversion_for_bitop_p (TREE_TYPE (arg1), TREE_TYPE (def1_arg1))
&& INTEGRAL_TYPE_P (TREE_TYPE (def1_arg1))
&& int_fits_type_p (arg2, TREE_TYPE (def1_arg1)))
{
@ -1816,15 +1841,7 @@ simplify_bitwise_binary (gimple_stmt_iterator *gsi)
if (CONVERT_EXPR_CODE_P (def1_code)
&& CONVERT_EXPR_CODE_P (def2_code)
&& types_compatible_p (TREE_TYPE (def1_arg1), TREE_TYPE (def2_arg1))
/* Make sure that the conversion widens the operands, or has same
precision, or that it changes the operation to a bitfield
precision. */
&& ((TYPE_PRECISION (TREE_TYPE (def1_arg1))
<= TYPE_PRECISION (TREE_TYPE (arg1)))
|| (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (arg1)))
!= MODE_INT)
|| (TYPE_PRECISION (TREE_TYPE (arg1))
!= GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (arg1))))))
&& hoist_conversion_for_bitop_p (TREE_TYPE (arg1), TREE_TYPE (def1_arg1)))
{
gimple newop;
tree tem = make_ssa_name (TREE_TYPE (def1_arg1), NULL);