[llvm-bugs] [Bug 34469] New: wrong code in Polly on x86_64-linux-gnu with "opt -instcombine -newgvn -polly-opt-isl -polly-mse -polly-codegen"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=34469

            Bug ID: 34469
           Summary: wrong code in Polly on x86_64-linux-gnu with "opt
                    -instcombine -newgvn -polly-opt-isl -polly-mse
                    -polly-codegen"
           Product: Polly
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Optimizer
          Assignee: polly-dev at googlegroups.com
          Reporter: su at cs.ucdavis.edu
                CC: llvm-bugs at lists.llvm.org

It might be a dup of or related to PR 34439 (and PR 34431). 


$ clangpolly -v
clang version 6.0.0 (http://llvm.org/git/clang.git
c55c0db172fe48c0ee64bd86d2cb35c3e38f328b) (http://llvm.org/git/llvm.git
cfc091852bfc3c1fe9c2731e73f7ee9e832a2e60)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/su/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
$ 
$ clangpolly -O3 -mllvm -disable-llvm-optzns -c -emit-llvm -o small.bc small.c
$ optpolly -instcombine -newgvn -polly-opt-isl -polly-mse -polly-codegen -o
small-opt.bc small.bc
$ clangpolly small-opt.bc 
$ ./a.out
0
$ 
$ clangpolly -O0 small.c; ./a.out
1
$ 


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


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

int a[16], b;

int main ()
{
  int c = 0;
  for (; c < 16; c++)
    {
      a[c] = c;
      b = a[1];
    }
  printf ("%d\n", b);
  return 0; 
}

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