[llvm-bugs] [Bug 41290] New: newgvn cannot terminate : out of memory

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=41290

            Bug ID: 41290
           Summary: newgvn cannot terminate : out of memory
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: cszide at 163.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 21698
  --> https://bugs.llvm.org/attachment.cgi?id=21698&action=edit
.bc file of the source code

$clang -v
clang version 9.0.0 (trunk 355281)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm/build4/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64

$clang -O3 -c -emit-llvm  -mllvm -disable-llvm-optzns small.c

$opt -mem2reg -reg2mem -instcombine -simplifycfg  small.bc -o small-opt.bc

$opt -newgvn small-opt.bc
In this step, opt will consume too much memory and not terminate.
By using godbolt, it shows that the llvm 6/7/truck version also has this
problem.

LLVM ERROR: out of memory

Stack dump:

0.      Program arguments: /opt/compiler-explorer/clang-trunk/bin/opt
-o/compiler-explorer/c-preload/compiler-wrapper: line 21: 31236 Alarm clock    
        "$@"

Compiler returned: 142

----------------------------------------------
a, c;
d() {
e:
  for (;;) {
    int f;
    for (; c;)
      for (; a; a++) {
        int b = 0;
        for (; b;)
          return c;
      }
    for (; 0;)
      goto e;
  }
}

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