https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110903
Bug ID: 110903
Summary: [14 Regression] Dead Code Elimination Regression since
r14-1597-g64d90d06d2d
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/7of4jjM3K
Given the following code:
void foo(void);
static char b, c;
static short e, f;
static int g = 41317;
static int(a)(int h, int i) { return h + i; }
static int(d)(int h, int i) { return i ? h : 0; }
int main() {
{
char j;
short k;
for (; g >= 10; g = (short)g) {
int l = 1, m = 0;
j = 8 * k;
k = j <= 0;
f = c + 3;
for (; c < 2; c = f) {
char n = 4073709551615;
if (!(((m) >= 0) && ((m) <= 0))) {
__builtin_unreachable();
}
if (g)
;
else {
if ((m = k, (b = a(d(l, k), e) && n) || l) < k) foo();
e = l = 0;
}
}
}
}
}
gcc-trunk -O3 does not eliminate the call to foo:
main:
movl g(%rip), %edi
cmpl $9, %edi
jle .L25
pushq %rbp
movl %edi, %ecx
movl $1, %ebp
movl $1, %esi
pushq %rbx
movl $1, %ebx
subq $8, %rsp
movzbl c(%rip), %edx
movsbw %dl, %ax
addl $3, %eax
movw %ax, f(%rip)
cmpb $1, %dl
jg .L12
.p2align 4,,10
.p2align 3
.L6:
testl %edi, %edi
je .L7
movb %al, c(%rip)
movsbw %al, %dx
cmpb $1, %al
jle .L6
.L9:
movswl %di, %ecx
movl %ecx, g(%rip)
cmpl $9, %ecx
jle .L17
addl $3, %edx
movw %dx, f(%rip)
.L12:
movswl %cx, %eax
cmpw $9, %cx
jle .L29
.L4:
jmp .L4
.p2align 4,,10
.p2align 3
.L7:
movswl e(%rip), %ecx
movl %ebx, %edx
andl %esi, %edx
addl %ecx, %edx
orl %esi, %edx
jne .L10
testb %bpl, %bpl
jne .L30
.L10:
xorl %edx, %edx
movb %al, c(%rip)
movw %dx, e(%rip)
movsbw %al, %dx
cmpb $1, %al
jg .L9
xorl %esi, %esi
jmp .L6
.p2align 4,,10
.p2align 3
.L30:
call foo
movzwl f(%rip), %eax
movl g(%rip), %edi
jmp .L10
.L29:
movl %eax, g(%rip)
.L17:
addq $8, %rsp
xorl %eax, %eax
popq %rbx
popq %rbp
ret
.L25:
xorl %eax, %eax
ret
gcc-13.2.0 -O3 eliminates the call to foo:
main:
movl g(%rip), %esi
movl %esi, %ecx
cmpl $9, %esi
jle .L14
movzbl c(%rip), %eax
movsbw %al, %dx
addl $3, %edx
movw %dx, f(%rip)
cmpb $1, %al
jg .L12
xorl %eax, %eax
testb %al, %al
movl %edx, %eax
je .L6
cmpb $1, %dl
jg .L22
.L7:
jmp .L7
.p2align 4,,10
.p2align 3
.L22:
movb %dl, c(%rip)
.L8:
movswl %si, %ecx
movl %ecx, g(%rip)
cmpl $9, %ecx
jle .L14
addl $3, %eax
cbtw
movw %ax, f(%rip)
.L12:
movswl %cx, %eax
cmpw $9, %cx
jle .L23
.L4:
jmp .L4
.p2align 4,,10
.p2align 3
.L6:
movb %dl, c(%rip)
cmpw $1, %dx
jg .L8
.p2align 4,,10
.p2align 3
.L9:
movl g(%rip), %eax
testl %eax, %eax
jne .L9
movw $0, e(%rip)
movb %dl, c(%rip)
.L23:
movl %eax, g(%rip)
.L14:
xorl %eax, %eax
ret
Bisects to r14-1597-g64d90d06d2d
