[llvm-bugs] [Bug 42660] New: indvars makes function broken with "opt -newgvn -reg2mem -licm -ipconstprop -loop-interchange -jump-threading -lcssa -indvars"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42660

            Bug ID: 42660
           Summary: indvars makes function broken with "opt -newgvn
                    -reg2mem -licm  -ipconstprop -loop-interchange
                    -jump-threading -lcssa -indvars"
           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 22254
  --> https://bugs.llvm.org/attachment.cgi?id=22254&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 -newgvn -reg2mem -licm  -ipconstprop -loop-interchange -jump-threading
-lcssa -indvars  small.bc -o small-opt.bc
PHI nodes must have at least one entry.  If the block is dead, the PHI should
be removed!
  %cleanup.dest23.lcssa37.lcssa38 = phi i32 
PHI nodes must have at least one entry.  If the block is dead, the PHI should
be removed!
  %.lcssa55 = phi i8* 
in function d
LLVM ERROR: Broken function found, compilation aborted!

------------------------------------------------------------
short a;
short(c)();
static int d(g) {
  if (c())
  h:
    for (;;) {
      int e;
      if (g)
        continue;
      for (;;) {
        char *b, *l;
        int m, f, i, j, k;
        if (a)
          goto h;
      }
    }
  return d(1);
}

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