https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113716
Bug ID: 113716
Summary: Missed optimization: (2/a)*b*(!b) => 0
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: 652023330028 at smail dot nju.edu.cn
Target Milestone: ---
Hello, we noticed that the code below can be optimized as stated in the title
((2/a)*b*(!b) => 0), but gcc -O3 -fwrapv missed it.
https://godbolt.org/z/34Ejoxeqo
int m;
void func(int a, int b){
a=(2/a)*b;
m=a*(!b);
}
GCC -O3 -fwrapv:
func(int, int):
xor edx, edx
mov eax, 2
idiv edi
xor edx, edx
test esi, esi
cmovne eax, edx
imul eax, esi
mov DWORD PTR m[rip], eax
ret
Expected code (Clang):
func(int, int): # @func(int, int)
mov dword ptr [rip + m], 0
ret
Thank you very much for your time and effort! We look forward to hearing from
you.
