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re PR middle-end/52134 (Does not fold (x * 4) & -4)

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2012-03-13  Richard Guenther  <rguenther@suse.de>

	PR middle-end/52134
	* fold-const.c (fold_binary_loc): Fold (X * Y) & -(1 << CST) to X * Y
	if Y is a constant multiple of 1 << CST.

	* gcc.dg/pr52134.c: New testcase.

From-SVN: r185334
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Richard Guenther 2012-03-13 13:47:35 +00:00 • committed by Richard Biener
parent 2895dfa417
commit 0c12cd5e90
4 changed files with 39 additions and 0 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2012-03-13 Richard Guenther <rguenther@suse.de>
PR middle-end/52134
* fold-const.c (fold_binary_loc): Fold (X * Y) & -(1 << CST) to X * Y
if Y is a constant multiple of 1 << CST.
2012-03-13 Georg-Johann Lay <avr@gjlay.de>
PR target/52488

14
gcc/fold-const.c
View file

@ -11398,6 +11398,20 @@ fold_binary_loc (location_t loc,
fold_convert_loc (loc, type, arg0));
}
/* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
multiple of 1 << CST. */
if (TREE_CODE (arg1) == INTEGER_CST)
{
double_int cst1 = tree_to_double_int (arg1);
double_int ncst1 = double_int_ext (double_int_neg (cst1),
TYPE_PRECISION (TREE_TYPE (arg1)),
TYPE_UNSIGNED (TREE_TYPE (arg1)));
if (double_int_equal_p (double_int_and (cst1, ncst1), ncst1)
&& multiple_of_p (type, arg0,
double_int_to_tree (TREE_TYPE (arg1), ncst1)))
return fold_convert_loc (loc, type, arg0);
}
/* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
((A & N) + B) & M -> (A + B) & M
Similarly if (N & M) == 0,

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2012-03-13 Richard Guenther <rguenther@suse.de>
PR middle-end/52134
* gcc.dg/pr52134.c: New testcase.
2012-03-13 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
* ada/acats/tests/cd/cdd1001.a (CDD1001): Fix typo.

14
gcc/testsuite/gcc.dg/pr52134.c Normal file
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@ -0,0 +1,14 @@
/* { dg-do compile } */
/* { dg-options "-fdump-tree-original" } */
unsigned f(unsigned t)
{
return (t*4)&-4;
}
int f1(int t)
{
return (t*4)&-4;
}
/* { dg-final { scan-tree-dump-not "\\\&" "original" } } */
/* { dg-final { cleanup-tree-dump "original" } } */