[clang] Miscompile at O3 with SIGKILL

[cardigan1008]

When I compiled this code with O3, it triggered SIGKILL. With O0/1/2, it returned 0.

Bisected to 5b92713, which was committed by @fhahn

Compiler Explorer: https://godbolt.org/z/q9j75feYG

Code:

int printf(const char *, ...);
int a, c, d;
int *b;
char e;
short f;
int g(int i) {
  if (i <= 0)
    return 1;
  int h = 0;
  for (; h < i - 1; h++) {
    for (; d - h - 1;)
      if (c)
        b[d] = e = 1;
    if (e)
      break;
  }
  return 0;
}
void j() { g(f); }
int main(int i, char *k[]) {
  j();
  while (0 < f)
    ;
  printf("%X\n", a);
}

[dtcxzyw]

Reproducer: https://alive2.llvm.org/ce/z/fLN5gw

; bin/opt -passes=constraint-elimination test.ll -S
define i1 @test(i16 %n) {
entry:
  %cond = icmp slt i16 %n, 1
  br i1 %cond, label %exit, label %loop.preheader

loop.preheader:
  %sub = add nsw i16 %n, -1
  %ext = zext nneg i16 %sub to i32
  br label %loop

loop:
  %indvar = phi i32 [ %indvar.inc, %loop.latch ], [ 0, %loop.preheader ]
  %12 = icmp eq i32 %indvar, %ext
  br i1 %12, label %exit, label %loop.latch

loop.latch:
  %indvar.inc = add nuw nsw i32 %indvar, 1
  br label %loop

exit:
  %cmp = icmp sgt i16 %n, 0
  ret i1 %cmp
}

I will post a fix later.