[llvm-bugs] [Bug 42448] New: loop-unswitch makes function broken with "opt -instcombine -lowerswitch -loop-rotate -jump-threading -lcssa -loop-unswitch"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42448

            Bug ID: 42448
           Summary: loop-unswitch makes function broken with "opt
                    -instcombine -lowerswitch -loop-rotate -jump-threading
                    -lcssa -loop-unswitch"
           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 22165
  --> https://bugs.llvm.org/attachment.cgi?id=22165&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 -instcombine -lowerswitch -loop-rotate -jump-threading -lcssa
-loop-unswitch small.bc -o small-opt.bc
PHI nodes must have at least one entry.  If the block is dead, the PHI should
be removed!
  %storemerge = phi i32 
in function e
LLVM ERROR: Broken function found, compilation aborted!

--------------------------------------------------
long a, b, d;
int c;
void e() {
f:
  for (;;) {
    int g;
    b = 0;
    for (; b <= 4;) {
      c = 1;
      for (; c;)
        goto f;
      for (; a;)
        for (; d;)
          ;
    }
  }
}

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20190630/b24953e9/attachment.html>