[Bug tree-optimization/94914] Failure to optimize check of high part of 64-bit result of 32 by 32 multiplication into overflow check
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Tue May 5 09:35:35 GMT 2020
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94914
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:6d938a5d770d0e94ecd923d20006b05126659235
commit r11-63-g6d938a5d770d0e94ecd923d20006b05126659235
Author: Jakub Jelinek <jakub@redhat.com>
Date: Tue May 5 11:31:43 2020 +0200
match.pd: Optimize (((type)A * B) >> prec) != 0 into __imag__ .MUL_OVERFLOW
[PR94914]
On x86 (the only target with umulv4_optab) one can use mull; seto to check
for overflow instead of performing wider multiplication and performing
comparison on the high bits.
2020-05-05 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/94914
* match.pd ((((type)A * B) >> prec) != 0 to .MUL_OVERFLOW(A, B) !=
0):
New simplification.
* gcc.target/i386/pr94914.c: New test.
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