https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114318
Bug ID: 114318
Summary: Missing Optimization after multiple function calls
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: carnet at student dot ethz.ch
Target Milestone: ---
GCC -O3 does not inline the function if there are more than two calls. This
also only happens in the main function. Changing the name of the main function
and/or reducing the number of function calls, enables the optimization.
https://godbolt.org/z/KM71WrYac
Source
int a, c, d;
int *b, *e;
static int *f() {
int *g = &d;
int **h = &b;
*g = 1;
*h = &c;
if (*b)
for (; d; d = d + 8)
;
return &d;
}
int main() {
f();
f();
f();
}
x86 -O3 Assembly:
f.part.0:
movl d(%rip), %eax
testl %eax, %eax
je .L1
movl $0, d(%rip)
.L1:
ret
main:
movl $1, d(%rip)
movl c(%rip), %ecx
testl %ecx, %ecx
je .L5
xorl %eax, %eax
call f.part.0
.L5:
movl $1, d(%rip)
movl c(%rip), %edx
testl %edx, %edx
je .L6
xorl %eax, %eax
call f.part.0
.L6:
movl $1, d(%rip)
movl c(%rip), %eax
movq $c, b(%rip)
testl %eax, %eax
je .L7
xorl %eax, %eax
call f.part.0
.L7:
xorl %eax, %eax
ret
e:
.zero 8
b:
.zero 8
d:
.zero 4
c:
.zero 4
a:
.zero 4
