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Fix PR tree-optimization/103228 and 103228: folding of (type) X op CST where type is a nop convert

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Currently we fold (type) X op CST into (type) (X op ((type-x) CST)) when the conversion widens
but not when the conversion is a nop. For the same reason why we move the widening conversion
(the possibility of removing an extra conversion), we should do the same if the conversion is a
nop.

Committed as approved with the comment change.

	PR tree-optimization/103228
	PR tree-optimization/55177

gcc/ChangeLog:

	* match.pd ((type) X bitop CST): Also do this
	transformation for nop conversions.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr103228-1.c: New test.
	* gcc.dg/tree-ssa/pr55177-1.c: New test.
This commit is contained in:
Andrew Pinski 2021-11-15 09:31:20 +00:00
parent 0e4a8656e8
commit 3222135700
3 changed files with 29 additions and 2 deletions
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6
gcc/match.pd
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@ -1616,8 +1616,10 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
Restrict it to GIMPLE to avoid endless recursions. */
&& (bitop != BIT_AND_EXPR || GIMPLE)
&& (/* That's a good idea if the conversion widens the operand, thus
after hoisting the conversion the operation will be narrower. */
TYPE_PRECISION (TREE_TYPE (@0)) < TYPE_PRECISION (type)
after hoisting the conversion the operation will be narrower.
It is also a good if the conversion is a nop as moves the
conversion to one side; allowing for combining of the conversions. */
TYPE_PRECISION (TREE_TYPE (@0)) <= TYPE_PRECISION (type)
/* It's also a good idea if the conversion is to a non-integer
mode. */
|| GET_MODE_CLASS (TYPE_MODE (type)) != MODE_INT

11
gcc/testsuite/gcc.dg/tree-ssa/pr103228-1.c Normal file
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@ -0,0 +1,11 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
int f(int a, int b)
{
b|=1u;
b|=2;
return b;
}
/* { dg-final { scan-tree-dump-times "\\\| 3" 1 "optimized"} } */
/* { dg-final { scan-tree-dump-times "\\\| 1" 0 "optimized"} } */
/* { dg-final { scan-tree-dump-times "\\\| 2" 0 "optimized"} } */

14
gcc/testsuite/gcc.dg/tree-ssa/pr55177-1.c Normal file
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@ -0,0 +1,14 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
extern int x;
void foo(void)
{
int a = __builtin_bswap32(x);
a &= 0x5a5b5c5d;
x = __builtin_bswap32(a);
}
/* { dg-final { scan-tree-dump-times "__builtin_bswap32" 0 "optimized"} } */
/* { dg-final { scan-tree-dump-times "& 1566333786" 1 "optimized"} } */
/* { dg-final { scan-tree-dump-times "& 1515936861" 0 "optimized"} } */