[llvm-bugs] [Bug 38304] New: clang miscompiles with "newgvn" at -O3 on valid code (32-bit only)

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=38304

            Bug ID: 38304
           Summary: clang miscompiles with "newgvn" at -O3 on valid code
                    (32-bit only)
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: LLVM Codegen
          Assignee: unassignedclangbugs at nondot.org
          Reporter: helloqirun at gmail.com
                CC: llvm-bugs at lists.llvm.org

clang-r325122: first working build
clang-r325127: next failing build

$ clang-trunk -v
clang version 7.0.0 (trunk 337816)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin


$ clang-trunk -O3  -m32  abc.c ; ./a.out
5

$ clang-trunk -mllvm -enable-newgvn -m32 -O3 abc.c ; ./a.out
0


$ cat abc.c
void printf();
int c, d, e, f, g = 5, i, j;
char h, k;
int __attribute__((noinline)) l(long long m) { return m; }
int(n)(int m, int p2) { return m - p2; }
short o() {
  k = 1;
  for (; k; k++) {
    if (d)
      continue;
    return 1;
  }
  for (; i <= 5; i++) {
    g = 0;
    if (l(0))
      e = 3;
  }
  return 1;
}
void p(unsigned m) {
  if (l(0)) {
    short a;
    for (; h; h++)
      a = e;
    f = (e | m) % a;
  }
}
short fn5() {
  int q;
  char b = 0;
  for (; b != 36; b = b + 9) {
    d = 0;
    for (; d > -20; --d) {
      p(b);
      o();
      j = 1 & ((1 | c && b || b) ^ 3);
      q = n(b, j);
      if (l(q))
        break;
    }
  }
  return b;
}
int main() {
  fn5();
  printf("%d\n", g);
}

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