[llvm-bugs] [Bug 38288] New: clang miscompiles with "-newgvn" at -O3 in 32-bit mode on valid code

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=38288

            Bug ID: 38288
           Summary: clang miscompiles with "-newgvn" at -O3 in 32-bit mode
                    on valid code
           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

It appears that it also affects the 64-bit mode.

clang-r333687: first working build
clang-r333691: 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 -m32 abc.c ; ./a.out
5

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


$ cat abc.c
void printf();
struct {
  int d;
} e, f;
int g, h, a, i, j;
char k, b;
short l = 5;
int __attribute__((noinline)) m(long long n) { return n; }
short(fn2)(char n) { return n; }
int(o)(int n, int p2) { return n - p2; }
void q(unsigned);
void r() {
  char p = 0;
  for (; p != 36; p = p + 9) {
    int s;
    h = 0;
    for (; h > -20; --h) {
      q(p);
      s = 1 & ((1 | g && p || p) ^ 3);
      i = o(p, s);
      if (m(i))
        ;
      else {
        for (; b;)
          fn2(p);
        l = 0;
      }
    }
  }
}
void q(unsigned n) {
  if (m(0)) {
    short c = 6;
    if (m(j))
      a = c = 0;
    for (; k; k++)
      e = f;
    a = (e.d | n) % c;
  }
}
int main() {
  r();
  printf("%d\n", l);
}

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