[llvm-bugs] [Bug 31077] New: wrong code with "opt -inline -instcombine -ipsccp -loop-extract"

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=31077

            Bug ID: 31077
           Summary: wrong code with "opt -inline -instcombine -ipsccp
                    -loop-extract"
           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 287325)
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 -inline -instcombine -ipsccp -loop-extract -o small-opt.bc small.bc
$ 
$ llc -o small.s small.bc
$ gcc small.s; ./a.out
$ 
$ llc -o small-opt.s small-opt.bc
$ gcc small-opt.s 
$ ./a.out
Segmentation fault (core dumped)
$ 
$ cat small.c
char a, e;
int b = 8, c, g;

void fn1 ()
{
  int d[7];
  for (; a;)
    d[1] ^= c;
}

int fn2 ()
{
  int h[7]= { 0, 0, 0, 0, 0, 0, 0 };
  --h[0];
  return g;
}

void fn3 ()
{
  for (; e < 1; e++)
    {
      int *f = &b;
      *f = fn2 ();
    }
}

int main ()
{
  fn3 ();
  fn1 ();
  return 0; 
}
$

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