[llvm-bugs] [Bug 32859] New: wrong code in NewGVN (with "opt -inline -sroa -jump-threading -lcssa -loop-rotate -loop-vectorize -loop-unroll -newgvn") on x86_64-linux-gnu

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=32859

            Bug ID: 32859
           Summary: wrong code in NewGVN (with "opt -inline -sroa
                    -jump-threading -lcssa -loop-rotate -loop-vectorize
                    -loop-unroll -newgvn") on x86_64-linux-gnu
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: su at cs.ucdavis.edu
                CC: llvm-bugs at lists.llvm.org

$ clang -v
clang version 5.0.0 (trunk 301671)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/clang-trunk/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.4
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.2.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$
$ clang -O0 small.c; ./a.out
1
1
1
1
1
1
1
1
1
1
$ clang -O3 -mllvm -disable-llvm-optzns -S -emit-llvm -o small.bc small.c
$ opt -inline -sroa -jump-threading -lcssa -loop-rotate -loop-vectorize
-loop-unroll -newgvn -o small-opt.bc small.bc
$ clang small-opt.bc; ./a.out
1
$


-------------------------------------------


int printf (const char *, ...);

int a = 1;

void foo ()
{ 
  int b, c, d;
  for (c = 0; c < 16; c++)
    for (b = c, d = 0; d < 3; d++)
      if (b & 1)
        b = 0;
}

int main ()
{ 
  int e;
  foo ();
  for (e = 0; e < 10; e++)
    { 
      int f = 1 / a;
      printf ("%d\n", (f && f == 1) || 0);
    }
  return 0;
}

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