[llvm-bugs] [Bug 31187] New: wrong code with "opt -loop-rotate -licm -loop-unroll"

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=31187

            Bug ID: 31187
           Summary: wrong code with "opt -loop-rotate -licm -loop-unroll"
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: su at cs.ucdavis.edu
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

$ clang -v
clang version 4.0.0 (trunk 287975)
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 -c -emit-llvm -o small.bc small.c
$ opt -loop-rotate -licm -loop-unroll -o small-opt.bc small.bc
$ llc -o small.s small-opt.bc
$ gcc small.s
$ ./a.out
0
$ 
$ clang -O0 small.c
$ ./a.out
1
$ 


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


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

unsigned a;
int b, c[9][8], d, e; 

int main ()
{
  {
    for (; e < 1; e++)
      {
        c[3][1] = 0;
        for (; a < 4; a++)
          for (; b < 9; b++)
            for (d = 0; d < 8; d++)
              c[b][d] = 1;
      }
  }
  printf ("%d\n", c[3][1]);
  return 0; 
}

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