https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112545
Bug ID: 112545
Summary: [14 Regression] Size regression when using -Os
starting with r14-569-g21e2ef2dc25
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: theodort at inf dot ethz.ch
Target Milestone: ---
https://godbolt.org/z/hcq8sKhvP
Given the following code:
static struct {
int a;
int b;
} c;
static int d, e, g;
static short f, i;
static void h(unsigned short j) {
c.a = i;
if (!(((j) >= 1) && ((j) <= 65535))) {
__builtin_unreachable();
}
}
int main1() {
d = 6;
for (; d != -7; d--) {
h(d ^ d < (0 <= 6));
if (d >= 12)
if (e) {
for (; f; ++f) g = c.b;
if (g) e = 0;
}
}
}
gcc-trunk -Os generates significantly more complex code:
main1:
movl e(%rip), %ecx
movl $6, %eax
xorl %edi, %edi
xorl %r8d, %r8d
movl c+4(%rip), %r10d
movl g(%rip), %esi
xorl %r9d, %r9d
movl $6, d(%rip)
movw f(%rip), %dx
.L2:
cmpl $-7, %eax
je .L31
xorl %r11d, %r11d
testl %eax, %eax
setle %r11b
cmpw %ax, %r11w
jne .L3
testb %r8b, %r8b
je .L4
movl %eax, d(%rip)
.L4:
testb %dil, %dil
je .L5
movl %ecx, e(%rip)
.L5:
xorl %ecx, %ecx
movw %dx, f(%rip)
movl %ecx, c(%rip)
movl %esi, g(%rip)
.L3:
cmpl $11, %eax
jle .L6
testl %ecx, %ecx
je .L6
.L7:
testw %dx, %dx
je .L32
incl %edx
movl %r10d, %esi
movb $1, %r9b
jmp .L7
.L32:
testl %esi, %esi
je .L6
movb $1, %dil
xorl %ecx, %ecx
.L6:
decl %eax
movb $1, %r8b
jmp .L2
.L31:
testb %r8b, %r8b
je .L10
movl $-7, d(%rip)
testb %dil, %dil
je .L11
movl %ecx, e(%rip)
.L11:
xorl %eax, %eax
movl %eax, c(%rip)
.L12:
testb %r9b, %r9b
je .L13
movw %dx, f(%rip)
movl %esi, g(%rip)
jmp .L13
.L10:
testb %dil, %dil
je .L12
movl %ecx, e(%rip)
jmp .L12
.L13:
xorl %eax, %eax
ret
than gcc-13.2.0 -Os:
main1:
movl $-7, d(%rip)
xorl %eax, %eax
movl %eax, c(%rip)
ret
Bisects to r14-569-g21e2ef2dc25
