[llvm-bugs] [Bug 41703] New: wrong code with "opt -loop-extract-single -mergereturn -structurizecfg -ipsccp -loop-simplify"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=41703

            Bug ID: 41703
           Summary: wrong code with "opt -loop-extract-single -mergereturn
                    -structurizecfg -ipsccp -loop-simplify"
           Product: libraries
           Version: 8.0
          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 21872
  --> https://bugs.llvm.org/attachment.cgi?id=21872&action=edit
.bc file of the source code

$clang -v
clang version 8.0.0 (tags/RELEASE_800/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir:
/home/jack-zhou/clang+llvm-8.0.0-x86_64-linux-gnu-ubuntu-18.04/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  -mllvm -disable-llvm-optzns small.c -o small.bc

$ clang small.bc -o small1.out && ./small1.out
0
0
0
0
3
0
0
0

$opt -loop-extract-single -mergereturn -structurizecfg -ipsccp -loop-simplify 
small.bc -o small-opt.bc

clang small-opt.bc -o small2.out && ./small2.out
0
0
0
0
0
0
0
0

---------------------------------------------
#include <stdio.h>
typedef signed char int8_t;
typedef short int int16_t;
typedef int int32_t;
typedef long int int64_t;

/* Unsigned.  */
typedef unsigned char uint8_t;
typedef unsigned short int uint16_t;
typedef unsigned int uint32_t;
typedef unsigned long int uint64_t;

int32_t a[8];
int32_t *b = &a[4];
uint8_t c = 3;
int32_t **d = &b;
uint8_t e;
uint16_t f(g) {
  uint16_t h = 2;
  int32_t ***m = &d;
  for (; h; ++h) {
    for (; e;) {
      int64_t j = 0;
      if (j)
        break;
    }
    ***m = c;
  }
  return 0;
}
void main() {
  int i, k = 0;
  int16_t l = 4;
  f(l);
  for (i = 0; i < 8; i++)
    printf("%d\n",a[i]);
}

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