[llvm-bugs] [Bug 42451] New: hotcoldsplit makes function broken with "opt -loop-unroll -mergereturn -hotcoldsplit -loop-rotate -sroa -inline -barrier -loop-idiom -early-cse -hotcoldsplit"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42451

            Bug ID: 42451
           Summary: hotcoldsplit makes function broken with "opt
                    -loop-unroll -mergereturn -hotcoldsplit -loop-rotate
                    -sroa -inline -barrier -loop-idiom -early-cse
                    -hotcoldsplit"
           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 22168
  --> https://bugs.llvm.org/attachment.cgi?id=22168&action=edit
.bc file of the source code

$clang -v
clang version 9.0.0 (trunk 363125)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/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 -loop-unroll -mergereturn -hotcoldsplit -loop-rotate  -sroa -inline
-barrier -loop-idiom -early-cse -hotcoldsplit  small.bc -o small-opt.bc
Instruction does not dominate all uses!
  %k.sroa.5.i = alloca [6 x i8], align 8
  %0 = bitcast [6 x i8]* %k.sroa.5.i to i8*
in function main
LLVM ERROR: Broken function found, compilation aborted!

-------------------------------------------------------
int a, b, c, g, h;
int i[2];
short l(d) {
  int e = 0;
  char f[6];
  for (; e < 6; e++)
    f[e] = 3;
  return 1;
}
int *m();
short o(int *j) {
  short k[3][3][2] = {1};
  k[2][1][1];
  k[1][2][1];
  return c;
}
void p() { m(); }
int *m() {
  {
    int n;
    b++;
    for (; 0;) {
      g;
      g++;
      for (; 0; 1)
        return 0;
    }
    a--;
  }
  for (;;)
    ;
}
void main() { h || l(o((p(), i))); }

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