[llvm-bugs] [Bug 40895] New: Consuming too much memory for "opt -mergereturn -loop-extract"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=40895

            Bug ID: 40895
           Summary: Consuming too much memory for "opt -mergereturn
                    -loop-extract"
           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 21524
  --> https://bugs.llvm.org/attachment.cgi?id=21524&action=edit
.bc file of the source code

$clang -v
clang version 9.0.0 (trunk 354742)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm/build/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 -o small.bc

$opt -mergereturn -loop-extract small.bc -o small-opt.bc

opt will consume too much memory and not terminate for a computer with 15GB
RAM.

The following is the source code of small.c, which is generated by csmith 2.4.0
and reduced by creduce 2.9.0 (eca4f38).

a, b;
c() {
  for (; a;)
    for (; b;)
      for (;;)
        ;
}

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