[llvm-bugs] [Bug 42018] New: loop-rotate makes function broken with "opt -licm -loop-rotate -jump-threading -lcssa -loop-rotate"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42018

            Bug ID: 42018
           Summary: loop-rotate makes function broken with "opt -licm
                    -loop-rotate -jump-threading -lcssa -loop-rotate"
           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 22018
  --> https://bugs.llvm.org/attachment.cgi?id=22018&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 -licm -loop-rotate -jump-threading -lcssa -loop-rotate  small.bc -o
small-opt.bc
PHI nodes must have at least one entry.  If the block is dead, the PHI should
be removed!
  %split = phi i32 
in function c
LLVM ERROR: Broken function found, compilation aborted!

without loop-rotate pass, opt works fine.
opt -licm -loop-rotate -jump-threading -lcssa  small.bc -o small-opt.bc

-----------------------------------------
int a=0, b=0;
c() {
  unsigned int d=0;
  unsigned short int e=0;
  for (; 4;) {
    int f=0;
    unsigned int g=0;
    unsigned int h=0;
    unsigned int k=0;
    unsigned int l=0;
    int i=0, j=0;
    for (d = 0; d <= 4; d++) {
      for (b = 1; b;)
        return e;
      for (; a; a++)
        f || 3;
    }
    for (; 0;)
      ;
  }
}

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