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re PR tree-optimization/14752 ([tree-ssa] "~a" should be changed to "a" if used in the condition of an if statement)

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PR middle-end/14752
	* c-common.c (c_common_truthvalue_conversion) <MINUS_EXPR,
	BIT_XOR_EXPR, BIT_AND_EXPR>: Delete.  Let fold optimize these
	cases via the construction of "expr != 0".

	* gcc.dg/fold-eqandshift-2.c: New test case.

From-SVN: r111575
This commit is contained in:
Roger Sayle 2006-02-28 21:31:29 +00:00 • committed by Roger Sayle
parent 63292ebfb4
commit c457fcec8e
4 changed files with 34 additions and 31 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-02-28 Roger Sayle <roger@eyesopen.com>
PR middle-end/14752
* c-common.c (c_common_truthvalue_conversion) <MINUS_EXPR,
BIT_XOR_EXPR, BIT_AND_EXPR>: Delete. Let fold optimize these
cases via the construction of "expr != 0".
2006-02-28 Steven Bosscher <stevenb.gcc@gmail.com>
* alias.c (alias_invariant, alias_invariant_size): Remove.

31
gcc/c-common.c
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@ -2537,37 +2537,6 @@ c_common_truthvalue_conversion (tree expr)
return c_common_truthvalue_conversion (TREE_OPERAND (expr, 0));
break;
case MINUS_EXPR:
/* Perhaps reduce (x - y) != 0 to (x != y). The expressions
aren't guaranteed to the be same for modes that can represent
infinity, since if x and y are both +infinity, or both
-infinity, then x - y is not a number.
Note that this transformation is safe when x or y is NaN.
(x - y) is then NaN, and both (x - y) != 0 and x != y will
be false. */
if (HONOR_INFINITIES (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0)))))
break;
/* Fall through.... */
case BIT_XOR_EXPR:
/* This and MINUS_EXPR can be changed into a comparison of the
two objects. */
if (TREE_TYPE (TREE_OPERAND (expr, 0))
== TREE_TYPE (TREE_OPERAND (expr, 1)))
return fold_build2 (NE_EXPR, truthvalue_type_node,
TREE_OPERAND (expr, 0), TREE_OPERAND (expr, 1));
return fold_build2 (NE_EXPR, truthvalue_type_node,
TREE_OPERAND (expr, 0),
fold_convert (TREE_TYPE (TREE_OPERAND (expr, 0)),
TREE_OPERAND (expr, 1)));
case BIT_AND_EXPR:
if (integer_onep (TREE_OPERAND (expr, 1))
&& TREE_TYPE (expr) != truthvalue_type_node)
/* Using convert here would cause infinite recursion. */
return build1 (NOP_EXPR, truthvalue_type_node, expr);
break;
case MODIFY_EXPR:
if (!TREE_NO_WARNING (expr))
warning (OPT_Wparentheses,

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2006-02-28 Roger Sayle <roger@eyesopen.com>
PR middle-end/14752
* gcc.dg/fold-eqandshift-2.c: New test case.
2006-02-28 Richard Guenther <rguenther@suse.de>
* gcc.dg/tree-ssa/pr26421.c: Fix testcase to force struct

22
gcc/testsuite/gcc.dg/fold-eqandshift-2.c Normal file
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@ -0,0 +1,22 @@
/* PR middle-end/14752 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-original" } */
void bar (void);
void foo (unsigned int a)
{
if ((a >> 2) & 1)
bar ();
}
void baz (unsigned int b)
{
if ((~b >> 2) & 1)
bar ();
}
/* { dg-final { scan-tree-dump-times "\\(a \& 4\\) != 0" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "\\(b \& 4\\) == 0" 1 "original" } } */
/* { dg-final { cleanup-tree-dump "original" } } */