[llvm-bugs] [Bug 36964] New: wrong code with opt "-jump-threading -loop-rotate -gvn -loop-unroll -memcpyopt -gvn"

via llvm-bugs llvm-bugs at lists.llvm.org
Fri Mar 30 21:40:12 PDT 2018


https://bugs.llvm.org/show_bug.cgi?id=36964

            Bug ID: 36964
           Summary: wrong code with opt "-jump-threading -loop-rotate -gvn
                    -loop-unroll -memcpyopt -gvn"
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: su at cs.ucdavis.edu
                CC: llvm-bugs at lists.llvm.org

$ clangpolly -v
clang version 7.0.0 (http://llvm.org/git/clang.git
e327c701dd9ac0a478f777a41a198010ee8ddeba) (llvm/trunk 328759)
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 -O0 -w small.c; ./a.out
$ 
$ clangpolly -O3 -mllvm -disable-llvm-optzns -w -c -emit-llvm -o small.bc
small.c
$ optpolly -jump-threading -loop-rotate -gvn -loop-unroll -memcpyopt -gvn -o
small-opt.bc small.bc
$ clangpolly small-opt.bc
$ ./a.out
Aborted (core dumped)
$ 


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


int a, *b = &a;

int main ()
{    
  int c[1], d[30], i, j;
  for (j = 0; j < 1; j++)
    c;
  for (i = 0; i < 3; i++)
    for (j = 0; j < 10; j++)
      d[i * 3 + j] = 0;
  *b = d[2];
  if (a != 0) 
    __builtin_abort ();
  return 0;  
}

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