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fold-const.c (fold_binary): Fold (~X & C) eq/ne 0 as (X & C) ne/eq 0, where C is a single bit, i.e.

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* fold-const.c (fold_binary) <EQ_EXPR>:  Fold (~X & C) eq/ne 0 as
	(X & C) ne/eq 0, where C is a single bit, i.e. a power of two.
	Fold both "((X & C) ^ C) eq/ne 0" and "((X ^ C) & C) eq/ne 0"
	as (X & C) ne/eq 0.

	* gcc.dg/fold-eqandnot-1.c: New test case.

From-SVN: r111471
This commit is contained in:
Roger Sayle 2006-02-27 03:22:18 +00:00 committed by Roger Sayle
parent 53f1b560db
commit 5881ad5d9d
4 changed files with 88 additions and 0 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-02-26 Roger Sayle <roger@eyesopen.com>
* fold-const.c (fold_binary) <EQ_EXPR>: Fold (~X & C) eq/ne 0 as
(X & C) ne/eq 0, where C is a single bit, i.e. a power of two.
Fold both "((X & C) ^ C) eq/ne 0" and "((X ^ C) & C) eq/ne 0"
as (X & C) ne/eq 0.
2006-02-26 Roger Sayle <roger@eyesopen.com>
PR middle-end/19983

44
gcc/fold-const.c
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@ -9868,6 +9868,50 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
fold_build2 (BIT_XOR_EXPR, TREE_TYPE (arg1),
TREE_OPERAND (arg0, 1), arg1));
/* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
(X & C) == 0 when C is a single bit. */
if (TREE_CODE (arg0) == BIT_AND_EXPR
&& TREE_CODE (TREE_OPERAND (arg0, 0)) == BIT_NOT_EXPR
&& integer_zerop (arg1)
&& integer_pow2p (TREE_OPERAND (arg0, 1)))
{
tem = fold_build2 (BIT_AND_EXPR, TREE_TYPE (arg0),
TREE_OPERAND (TREE_OPERAND (arg0, 0), 0),
TREE_OPERAND (arg0, 1));
return fold_build2 (code == EQ_EXPR ? NE_EXPR : EQ_EXPR,
type, tem, arg1);
}
/* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
constant C is a power of two, i.e. a single bit. */
if (TREE_CODE (arg0) == BIT_XOR_EXPR
&& TREE_CODE (TREE_OPERAND (arg0, 0)) == BIT_AND_EXPR
&& integer_zerop (arg1)
&& integer_pow2p (TREE_OPERAND (arg0, 1))
&& operand_equal_p (TREE_OPERAND (TREE_OPERAND (arg0, 0), 1),
TREE_OPERAND (arg0, 1), OEP_ONLY_CONST))
{
tree arg00 = TREE_OPERAND (arg0, 0);
return fold_build2 (code == EQ_EXPR ? NE_EXPR : EQ_EXPR, type,
arg00, build_int_cst (TREE_TYPE (arg00), 0));
}
/* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
when is C is a power of two, i.e. a single bit. */
if (TREE_CODE (arg0) == BIT_AND_EXPR
&& TREE_CODE (TREE_OPERAND (arg0, 0)) == BIT_XOR_EXPR
&& integer_zerop (arg1)
&& integer_pow2p (TREE_OPERAND (arg0, 1))
&& operand_equal_p (TREE_OPERAND (TREE_OPERAND (arg0, 0), 1),
TREE_OPERAND (arg0, 1), OEP_ONLY_CONST))
{
tree arg000 = TREE_OPERAND (TREE_OPERAND (arg0, 0), 0);
tem = fold_build2 (BIT_AND_EXPR, TREE_TYPE (arg000),
arg000, TREE_OPERAND (arg0, 1));
return fold_build2 (code == EQ_EXPR ? NE_EXPR : EQ_EXPR, type,
tem, build_int_cst (TREE_TYPE (tem), 0));
}
if (integer_zerop (arg1)
&& tree_expr_nonzero_p (arg0))
{

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2006-02-26 Roger Sayle <roger@eyesopen.com>
* gcc.dg/fold-eqandnot-1.c: New test case.
2006-02-26 Roger Sayle <roger@eyesopen.com>
PR middle-end/19983

33
gcc/testsuite/gcc.dg/fold-eqandnot-1.c Normal file
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@ -0,0 +1,33 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-original" } */
int test1(int a)
{
return !(a & 4);
}
int test2(int b)
{
return (b & 4) == 0;
}
int test3(int c)
{
return ((c & 4) ^ 4) != 0;
}
int test4(int d)
{
return ((d ^ 4) & 4) != 0;
}
int test5(int e)
{
return (~e & 4) != 0;
}
/* { dg-final { scan-tree-dump-times "\\(a \& 4\\) == 0" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "\\(b \& 4\\) == 0" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "\\(c \& 4\\) == 0" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "\\(d \& 4\\) == 0" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "\\(e \& 4\\) == 0" 1 "original" } } */
/* { dg-final { cleanup-tree-dump "original" } } */