https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99373
--- Comment #2 from Zhendong Su <zhendong.su at inf dot ethz.ch> ---
The following might be the same/related. The dead call is eliminated if b is
changed to:
static int b(int *c) {
foo();
d++;
}
[623] % gcctk -O3 -S small.c
[624] %
[624] % cat small.c
extern void foo(void);
static int a, d;
static int b(int *c) {
while (1) {
foo();
d++;
}
}
int main () {
a && b(&a);
return 0;
}
[625] %
[625] % cat small.s
.file "small.c"
.text
.section .text.startup,"ax",@progbits
.p2align 4
.globl main
.type main, @function
main:
.LFB1:
.cfi_startproc
movl a(%rip), %edx
testl %edx, %edx
jne .L7
xorl %eax, %eax
ret
.L7:
pushq %rax
.cfi_def_cfa_offset 16
.L3:
call foo
addl $1, d(%rip)
jmp .L3
.cfi_endproc
.LFE1:
.size main, .-main
.local d
.comm d,4,4
.local a
.comm a,4,4
.ident "GCC: (GNU) 11.0.1 20210304 (experimental) [master revision
cdfc2f6a6dc:ab3cea6cccd:f3641ac70eb0ae9f8983b7ddb1660c92439565de]"
.section .note.GNU-stack,"",@progbits
