[llvm-bugs] [Bug 43218] New: instsimplify crashes with segmentation fault

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=43218

            Bug ID: 43218
           Summary: instsimplify crashes with segmentation fault
           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 22468
  --> https://bugs.llvm.org/attachment.cgi?id=22468&action=edit
.bc file of the source code

$clang -v
clang version 10.0.0 (trunk 370163)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/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/7.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.4.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64

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

$opt -load-store-vectorizer -sroa -jump-threading -instsimplify small.bc -o
small-opt.bc
Stack dump:
0.      Program arguments:
/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt
-load-store-vectorizer -sroa -jump-threading -instsimplify small.bc -o
small-opt.bc 
1.      Running pass 'Function Pass Manager' on module 'small.bc'.
2.      Running pass 'Remove redundant instructions' on function '@a'
  #0 0x000055deac2787fa llvm::sys::PrintStackTrace(llvm::raw_ostream&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x27277fa)
  #1 0x000055deac2764d4 llvm::sys::RunSignalHandlers()
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x27254d4)
  #2 0x000055deac276612 SignalHandler(int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x2725612)
  #3 0x00007f918413e890 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x12890)
...
...
...
#253 0x000055deab6a60ac llvm::findScalarElement(llvm::Value*, unsigned int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x1b550ac)
#254 0x000055deab6a60ac llvm::findScalarElement(llvm::Value*, unsigned int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x1b550ac)
#255 0x000055deab6a60ac llvm::findScalarElement(llvm::Value*, unsigned int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x1b550ac)
Segmentation fault (core dumped)

By using bugpoint, the optimization sequences can be further reduced.

$opt bugpoint-reduced-simplified.bc -instsimplify
Stack dump:
0.      Program arguments:
/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt
bugpoint-reduced-simplified.bc -instsimplify 
1.      Running pass 'Function Pass Manager' on module
'bugpoint-reduced-simplified.bc'.
2.      Running pass 'Remove redundant instructions' on function '@a'
  #0 0x0000561c4bc367fa llvm::sys::PrintStackTrace(llvm::raw_ostream&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x27277fa)
  #1 0x0000561c4bc344d4 llvm::sys::RunSignalHandlers()
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x27254d4)
  #2 0x0000561c4bc34612 SignalHandler(int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x2725612)
  #3 0x00007fc9921ed890 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x12890)
  #4 0x0000561c4b063f32 llvm::findScalarElement(llvm::Value*, unsigned int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x1b54f32)
...
...
...
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x1b550ac)
#254 0x0000561c4b0640ac llvm::findScalarElement(llvm::Value*, unsigned int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x1b550ac)
#255 0x0000561c4b0640ac llvm::findScalarElement(llvm::Value*, unsigned int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build6/bin/opt+0x1b550ac)
Segmentation fault (core dumped)

----------------------------------------------
void a() {
  short ***b, ***c;
  short ****d[] = {&c, &c, &b, &c};
  for (; 0;)
    for (;;) {
      short *****e = &d[3];
      *e = d[2];
    }
}

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