https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111012
Bug ID: 111012
Summary: [14 Regression] Dead Code Elimination Regression at
-O3 since r14-573-g69f1a8af45d
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: scherrer.sv at gmail dot com
Target Milestone: ---
static int b, c;
static char d;
static short e = -1L;
static int *j = &c;
void foo(void);
void bar150_(void);
void bar173_(void);
static char(a)(char k, char l) { return k + l; }
static void g(unsigned k, int l) {
if (l)
if (!k)
foo();
if (k)
bar150_();
}
static const unsigned char h();
static char i(int k) {
if (k)
bar173_();
c <= 0 >= b;
if (k)
return c;
return c;
}
static void f(char k, unsigned) {
char m = h(8 != c);
g(m && 8, k);
}
static const unsigned char h(int k) {
d = i(c);
*j = a(e, d < k < k && c) ^ k;
b = 0;
return c;
}
int main() { f(c, b); }
gcc-9ec5d6de735 (trunk) -O3 cannot eliminate the call to foo but
gcc-releases/gcc-13.1.0 -O3 can.
-----------------------------------------------------------------------
gcc-9ec5d6de7355c15b3811150d1581dab5bd489966 -O3 case.c -S -o case.s
--------- OUTPUT ---------
main:
.LFB5:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
pushq %rbx
.cfi_def_cfa_offset 24
.cfi_offset 3, -24
subq $8, %rsp
.cfi_def_cfa_offset 32
movl c(%rip), %ebx
cmpl $8, %ebx
setne %bpl
testl %ebx, %ebx
jne .L9
movl $-2, c(%rip)
xorl %eax, %eax
movl %eax, b(%rip)
.L4:
call bar150_
.L6:
addq $8, %rsp
.cfi_remember_state
.cfi_def_cfa_offset 24
xorl %eax, %eax
popq %rbx
.cfi_def_cfa_offset 16
popq %rbp
.cfi_def_cfa_offset 8
ret
.p2align 4,,10
.p2align 3
.L9:
.cfi_restore_state
call bar173_
movl c(%rip), %edx
movzbl %bpl, %ebp
movl $0, b(%rip)
movsbl %dl, %eax
cmpl %eax, %ebp
setg %al
movzbl %al, %eax
cmpl %eax, %ebp
setg %al
testl %edx, %edx
setne %dl
andl %edx, %eax
subl $1, %eax
movsbl %al, %eax
xorl %ebp, %eax
movl %eax, c(%rip)
testb %bl, %bl
je .L3
testb %al, %al
jne .L4
call foo
jmp .L6
.L3:
testb %al, %al
je .L6
jmp .L4
---------- END OUTPUT ---------
-----------------------------------------------------------------------
gcc-2b98cc24d6af0432a74f6dad1c722ce21c1f7458 -O3 case.c -S -o case.s
--------- OUTPUT ---------
main:
.LFB5:
.cfi_startproc
movl c(%rip), %eax
pushq %rbx
.cfi_def_cfa_offset 16
.cfi_offset 3, -16
xorl %ebx, %ebx
cmpl $8, %eax
setne %bl
testl %eax, %eax
jne .L10
.L2:
cmpl %eax, %ebx
setg %al
movzbl %al, %eax
cmpl %eax, %ebx
jg .L3
notl %ebx
.L4:
movl %ebx, c(%rip)
movl $0, b(%rip)
call bar150_
xorl %eax, %eax
popq %rbx
.cfi_remember_state
.cfi_def_cfa_offset 8
ret
.L3:
.cfi_restore_state
cmpl $1, c(%rip)
sbbb %bl, %bl
xorl $1, %ebx
movsbl %bl, %ebx
jmp .L4
.L10:
call bar173_
movsbl c(%rip), %eax
jmp .L2
---------- END OUTPUT ---------
-----------------------------------------------------------------------
Bisects to r14-573-g69f1a8af45d
