https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115004
Bug ID: 115004
Summary: [11/12/13/14/15 Regression] Missed optimization for
Dead Code Elimination
Product: gcc
Version: 15.0
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 by Dead Code
Elimination, but gcc -O3 missed it.
This is a regression from GCC-8.1.
https://godbolt.org/z/7e64e56Mq
int m;
void fn(signed char p1, short p2, signed char p3_1, signed char p3_2, short p4,
unsigned char p5) {
if(
(signed char)((p4 | 0) && (p1 || p2) || p5 || p3_1 && p5)
-
(signed char)((p4 | 0) && (p1 || p2) || p5 || p3_2 && p5)
)
{ m=1; }
}
GCC -O3:
fn(signed char, short, signed char, signed char, short, unsigned char):
test r8w, r8w
je .L1
test dil, dil
setne al
test si, si
setne dl
or eax, edx
test r9b, r9b
jne .L6
.L1:
ret
.L6:
test al, al
jne .L1
test r9b, r9b
jne .L1
mov DWORD PTR m[rip], 1
ret
Expected code (GCC-7.5):
fn(signed char, short, signed char, signed char, short, unsigned char):
rep ret
Thank you very much for your time and effort! We look forward to hearing from
you.
