procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

fold-const.c (fold_binary_loc): New transformation.

Browse source 
2010-10-20  Dmitry Melnik  <dm@ispras.ru>

gcc/
	* fold-const.c (fold_binary_loc): New transformation.

gcc/testsuite/
	* gcc.dg/20101013-1.c: New test.

From-SVN: r165720
This commit is contained in:
Dmitry Melnik 2010-10-20 12:26:10 +00:00 • committed by Alexander Monakov
parent b9121f42a1
commit 2298ade7e5
4 changed files with 44 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
gcc/ChangeLog
View file

@ -1,3 +1,7 @@
2010-10-20 Dmitry Melnik <dm@ispras.ru>
* fold-const.c (fold_binary_loc): New transformation.
2010-10-20 H.J. Lu <hongjiu.lu@intel.com>
PR target/46085

25
gcc/fold-const.c
View file

@ -11599,6 +11599,31 @@ fold_binary_loc (location_t loc,
return NULL_TREE;
case TRUNC_DIV_EXPR:
/* Optimize (X & (-A)) / A where A is a power of 2,
to X >> log2(A) */
if (TREE_CODE (arg0) == BIT_AND_EXPR
&& !TYPE_UNSIGNED (type) && TREE_CODE (arg1) == INTEGER_CST
&& integer_pow2p (arg1) && tree_int_cst_sgn (arg1) > 0)
{
tree sum = fold_binary_loc (loc, PLUS_EXPR, TREE_TYPE (arg1),
arg1, TREE_OPERAND (arg0, 1));
if (sum && integer_zerop (sum)) {
unsigned long pow2;
if (TREE_INT_CST_LOW (arg1))
pow2 = exact_log2 (TREE_INT_CST_LOW (arg1));
else
pow2 = exact_log2 (TREE_INT_CST_HIGH (arg1))
+ HOST_BITS_PER_WIDE_INT;
return fold_build2_loc (loc, RSHIFT_EXPR, type,
TREE_OPERAND (arg0, 0),
build_int_cst (NULL_TREE, pow2));
}
}
/* Fall thru */
case FLOOR_DIV_EXPR:
/* Simplify A / (B << N) where A and B are positive and B is
a power of 2, to A >> (N + log2(B)). */

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2010-10-20 Dmitry Melnik <dm@ispras.ru>
* gcc.dg/20101013-1.c: New test.
2010-10-20 H.J. Lu <hongjiu.lu@intel.com>
PR target/46085

11
gcc/testsuite/gcc.dg/20101013-1.c Normal file
View file

@ -0,0 +1,11 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
int foo(int a)
{
int x = (a & (~15)) / 16;
return x;
}
/* { dg-final { scan-tree-dump ">>" "optimized" } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */