fold: Remove (rrotate (rrotate A CST) CST) folding [PR117492]

This removes an (broken) simplification from fold which is already handled in match.
The reason why it was broken is because of the use of wi::to_wide on the RHS of the
rotate which could be 2 different types even though the LHS was the same type.
Since it is already handled in match (by the patterns for
`Turn (a OP c1) OP c2 into a OP (c1+c2).`). It can be removed without losing any optimizations.

Bootstrapped and tested on x86_64-linux-gnu.

	PR middle-end/117492

gcc/ChangeLog:

	* fold-const.cc (fold_binary_loc): Remove `Two consecutive rotates adding up
	to the some integer` simplifcation.

gcc/testsuite/ChangeLog:

	* gcc.dg/torture/pr117492-1.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
This commit is contained in:
Andrew Pinski 2024-11-08 14:46:18 -08:00
parent 6e84a41622
commit ed88bc2344
2 changed files with 16 additions and 10 deletions

View File

@ -12530,16 +12530,6 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type,
arg01, arg1)); arg01, arg1));
} }
/* Two consecutive rotates adding up to the some integer
multiple of the precision of the type can be ignored. */
if (code == RROTATE_EXPR && TREE_CODE (arg1) == INTEGER_CST
&& TREE_CODE (arg0) == RROTATE_EXPR
&& TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
&& wi::umod_trunc (wi::to_wide (arg1)
+ wi::to_wide (TREE_OPERAND (arg0, 1)),
prec) == 0)
return fold_convert_loc (loc, type, TREE_OPERAND (arg0, 0));
return NULL_TREE; return NULL_TREE;
case MIN_EXPR: case MIN_EXPR:

View File

@ -0,0 +1,16 @@
/* { dg-do compile } */
/* PR middle-end/117492 */
/* This code would ICE in fold due to code which was using wi::to_wide with different types
and adding them. */
typedef unsigned u;
u
foo(u x)
{
return
__builtin_stdc_rotate_left((unsigned)
__builtin_stdc_rotate_right(x, 0x100000001ull),
1);
}