Extended Description

cat test.c
void foo(void);

static int a;
static int *b = &a;
static int **c = &b;
static char e;

static unsigned d() {
if (c)
return a;
else
return 1;
}

int main() {
int f = d();
unsigned char g = f;
e = g >> 4;
if (e) {
for (;;) {
if (f)
break;
c = 0;
foo();
}
for (;;)
;
}
}

13.0.0 at -O3 can eliminate the call to foo but trunk cannot:

clang-13 -O3 -S -o /dev/stdout test.c
...
main: # @​main
.cfi_startproc

%bb.0:

testb	$-16, a(%rip)
je	.LBB0_2
.p2align	4, 0x90

.LBB0_1: # =>This Inner Loop Header: Depth=1
jmp .LBB0_1
.LBB0_2:
xorl %eax, %eax
retq

clang-trunk -O3 -S -o /dev/stdout test.c
main: # @​main
.cfi_startproc

%bb.0:

pushq	%rax
.cfi_def_cfa_offset 16
cmpq	$0, c(%rip)
movl	$1, %eax
je	.LBB0_2

%bb.1:

movl	a(%rip), %eax

.LBB0_2:
cmpb $16, %al
jae .LBB0_3

%bb.6:

xorl	%eax, %eax
popq	%rcx
.cfi_def_cfa_offset 8
retq

.LBB0_3:
.cfi_def_cfa_offset 16
testl %eax, %eax
je .LBB0_4
.p2align 4, 0x90
.LBB0_5: # =>This Inner Loop Header: Depth=1
jmp .LBB0_5
.p2align 4, 0x90
.LBB0_4: # =>This Inner Loop Header: Depth=1
movq $0, c(%rip)
callq foo
jmp .LBB0_4

clang-trunk -v
clang version 14.0.0 (https://github.com/llvm/llvm-project.git eda2ebd)
Target: x86_64-unknown-linux-gnu
Thread model: posix

f32c0fe introduced this regression