[llvm-bugs] [Bug 41725] New: loop-interchange makes function broken with "opt -instcombine -licm -structurizecfg -jump-threading -loop-rotate -instcombine -loop-interchange"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=41725

            Bug ID: 41725
           Summary: loop-interchange makes function broken with "opt
                    -instcombine -licm -structurizecfg -jump-threading
                    -loop-rotate -instcombine -loop-interchange"
           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 21889
  --> https://bugs.llvm.org/attachment.cgi?id=21889&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 -instcombine -licm -structurizecfg -jump-threading -loop-rotate
-instcombine -loop-interchange small.bc -o small-opt.bc
Instruction does not dominate all uses!
  %8 = add nsw i32 %storemerge14, -1
  %.lcssa = phi i32 [ %8, %Flow3 ]
in function d
LLVM ERROR: Broken function found, compilation aborted!


without scalarizer pass, opt works fine.
$opt -instcombine -licm -structurizecfg -jump-threading -loop-rotate
-instcombine small.bc -o small-opt.bc

------------------------------------------------------
int a, b;
int c[10][1];
int d() {
  a = 0;
  for (; a <= 1; a++) {
    b = 5;
    for (; b; b--)
      c[b][a] = 0;
  }
}

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