https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110891
Bug ID: 110891
Summary: [14 Regression] Dead Code Elimination Regression since
r14-2674-gd0de3bf9175
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/njdE3xof4
Given the following code:
void foo(void);
static int a, c = 7, d, o, q;
static int *b = &a, *f, *j = &d, *n = &c, *ae;
static short e, m;
static short *i = &e;
static char r;
void __assert_fail(char *, char *, int, char *) __attribute__((__noreturn__));
static const short g();
static void h();
static int *k(int) {
(*i)++;
*j ^= *b;
return &a;
}
static void l(unsigned p) {
int *aa = &o;
h();
o = 5 ^ g() && p;
if (f == &d || f == &c || f == &a)
;
else {
foo();
__assert_fail("", "", 3, __PRETTY_FUNCTION__);
}
*aa ^= *n;
if (*aa)
if (!(((p) >= 0) && ((p) <= 0))) {
__builtin_unreachable();
}
k(p);
}
static const short g() { return q; }
static void h() {
unsigned ag = c;
d = ag > r ? ag : 0;
ae = k(c);
f = ae;
if (ae == &d || ae == &c || ae == &a)
;
else
__assert_fail("", "", 4, __PRETTY_FUNCTION__);
}
int main() {
l(a);
m || (*b |= 64);
*b &= 5;
}
gcc-trunk -O2 does not eliminate the call to foo:
main:
subq $8, %rsp
movl c(%rip), %eax
movl %eax, d(%rip)
call k.isra.0
cmpq $c, %rax
movq %rax, f(%rip)
sete %cl
cmpq $a, %rax
sete %dil
cmpq $d, %rax
sete %dl
orb %cl, %dl
jne .L4
testb %dil, %dil
je .L15
.L4:
cmpq $d, %rax
je .L6
testb %cl, %cl
jne .L6
testb %dil, %dil
je .L16
.L6:
call k.isra.0
andl $5, a(%rip)
xorl %eax, %eax
addq $8, %rsp
ret
.L16:
call foo
movl $.LC0, %esi
movl $__PRETTY_FUNCTION__.1, %ecx
movl $3, %edx
movq %rsi, %rdi
call __assert_fail
.L15:
movl $.LC0, %esi
movl $__PRETTY_FUNCTION__.0, %ecx
movl $4, %edx
movq %rsi, %rdi
call __assert_fail
gcc-13.2.0 -O2 eliminates the call to foo:
main:
subq $8, %rsp
movl c(%rip), %eax
movl %eax, d(%rip)
call k.isra.0
cmpq $c, %rax
movq %rax, f(%rip)
sete %dl
cmpq $d, %rax
sete %cl
orb %cl, %dl
jne .L4
cmpq $a, %rax
jne .L6
.L4:
call k.isra.0
andl $5, a(%rip)
xorl %eax, %eax
addq $8, %rsp
ret
.L6:
movl $.LC0, %esi
movl $__PRETTY_FUNCTION__.0, %ecx
movl $4, %edx
movq %rsi, %rdi
call __assert_fail
Bisects to r14-2674-gd0de3bf9175
