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re PR tree-optimization/14847 ([tree-ssa] combine "if (a & 1) goto there" and "if (a & 4) goto there")

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2008-04-30  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/14847
	* tree-ssa-ifcombine.c (get_name_for_bit_test): New helper function.
	(recognize_bits_test): Use it.
	(recognize_single_bit_test): Likewise.

	* gcc.dg/tree-ssa/ssa-ifcombine-6.c: New testcase.

From-SVN: r134825
This commit is contained in:
Richard Guenther 2008-04-30 15:06:16 +00:00 • committed by Richard Biener
parent 56b1a55446
commit d7b339dd2a
4 changed files with 77 additions and 2 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2008-04-30 Richard Guenther <rguenther@suse.de>
PR tree-optimization/14847
* tree-ssa-ifcombine.c (get_name_for_bit_test): New helper function.
(recognize_bits_test): Use it.
(recognize_single_bit_test): Likewise.
2008-04-30 Martin Jambor <mjambor@suse.cz>
* ipa-cp.c (ipcp_init_stage): Calls ipa_set_called_with_variable_arg

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2008-04-30 Richard Guenther <rguenther@suse.de>
PR tree-optimization/14847
* gcc.dg/tree-ssa/ssa-ifcombine-6.c: New testcase.
2008-04-30 Jakub Jelinek <jakub@redhat.com>
PR c++/35986

37
gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-6.c Normal file
View file

@ -0,0 +1,37 @@
/* { dg-do compile } */
/* { dg-options "-O -fdump-tree-ifcombine" } */
void bar (void);
void
foo1 (unsigned int a)
{
if (a & 1)
goto heaven;
if (a & 4)
goto heaven;
return;
heaven:
bar ();
}
void
foo2 (unsigned int a)
{
if (a & 1)
if (a & 4)
goto heaven;
return;
heaven:
bar ();
}
/* The special treatment of a & 1 != 0 in fold caused the pattern not
to be recognized due to extra conversions inserted. */
/* { dg-final { scan-tree-dump "optimizing bits or bits test" "ifcombine" } } */
/* { dg-final { scan-tree-dump "optimizing double bit test" "ifcombine" } } */
/* { dg-final { cleanup-tree-dump "ifcombine" } } */

30
gcc/tree-ssa-ifcombine.c
View file

@ -135,6 +135,32 @@ same_phi_args_p (basic_block bb1, basic_block bb2, basic_block dest)
return true;
}
/* Return the best representative SSA name for CANDIDATE which is used
in a bit test. */
static tree
get_name_for_bit_test (tree candidate)
{
/* Skip single-use names in favor of using the name from a
non-widening conversion definition. */
if (TREE_CODE (candidate) == SSA_NAME
&& has_single_use (candidate))
{
tree def_stmt = SSA_NAME_DEF_STMT (candidate);
if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
&& (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
|| TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == CONVERT_EXPR))
{
tree rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
if (TYPE_PRECISION (TREE_TYPE (rhs))
<= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (rhs, 0))))
return TREE_OPERAND (rhs, 0);
}
}
return candidate;
}
/* Recognize a single bit test pattern in COND_EXPR and its defining
statements. Store the name being tested in *NAME and the bit
in *BIT. The COND_EXPR computes *NAME & (1 << *BIT).
@ -192,7 +218,7 @@ recognize_single_bit_test (tree cond_expr, tree *name, tree *bit)
{
/* t & 1 */
*bit = integer_zero_node;
*name = orig_name;
*name = get_name_for_bit_test (orig_name);
}
return true;
@ -272,7 +298,7 @@ recognize_bits_test (tree cond_expr, tree *name, tree *bits)
if (TREE_CODE (t) != BIT_AND_EXPR)
return false;
*name = TREE_OPERAND (t, 0);
*name = get_name_for_bit_test (TREE_OPERAND (t, 0));
*bits = TREE_OPERAND (t, 1);
return true;