Wrong code at -Os on x86-64_gnu-linux (recent regression)

[shao-hua-li]

Clang at -Os produced the wrong code.

Bisected to dce77a3, which was committed by @fhahn

Compiler explorer: https://godbolt.org/z/fTrenPK4h

% cat reduced.c
int printf(const char *, ...);
int a, b, c, d, e;
int f[9];
int g(int i) {
  c = 1 << i;
  if (b & c)
    return 4;
  return 0;
}
int j(int i) {
  int h = g(i);
  return h;
}
int k() {
  d = 6;
  for (; d; d--) {
    e = 0;
    for (; e <= 6; e++) {
      f[j(d - 1)] = f[d];
      for (; e + d;)
        return 0;
    }
  }
  return 0;
}
int main() {
  k();
  printf("%d\n", a);
}
%
% clang -O3 reduced.c && ./a.out
0
% clang -Os reduced.c && ./a.out

%

[fhahn]

The issue is that IndVars doesn't drop poison-generating flags when hoisting the IV to introduce a new use of the widened IV. working on a fix

[fhahn]

Should be fixed, thanks again as always @shao-hua-li

[shao-hua-li]

You're welcome @fhahn