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 eda2ebd7807376829eb880c39623f364b438971f)
Target: x86_64-unknown-linux-gnu
Thread model: posix

https://github.com/llvm/llvm-project/commit/f32c0fe8e50534f4210d878b9a1420793860c567 introduced this regression