[llvm-bugs] [Bug 45743] New: Assertion `OuterLoop->isLCSSAForm(*DT) && "Outer loop not left in LCSSA form after loop interchange!"' failed

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45743

            Bug ID: 45743
           Summary: Assertion `OuterLoop->isLCSSAForm(*DT) && "Outer loop
                    not left in LCSSA form after loop interchange!"'
                    failed
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Loop Optimizer
          Assignee: unassignedbugs at nondot.org
          Reporter: balarishi.bhogadi at amd.com
                CC: llvm-bugs at lists.llvm.org

The below issue was introduced in trunk in March 2nd week.

$ cat foo.c
int a, c, d, e;
int b[2][10];
void fn1() {
  for (; c; c++) {
    e = 0;
    for (; e; e++)
      ;
    d = 5;
    for (; d; d--)
      a |= b[d][c + 9];
  }
}


$ clang -c -O2 -mllvm -enable-loopinterchange foo.c
clang:
/home/llvm-trunk/llvm-project/llvm/lib/Transforms/Scalar/LoopInterchange.cpp:586:
bool {anonymous}::LoopInterchange::processLoop({anonymous}::LoopVector,
unsigned int, unsigned int, llvm::BasicBlock*, std::vector<std::vector<char,
std::allocator<char> > >&): Assertion `OuterLoop->isLCSSAForm(*DT) && "Outer
loop not left in LCSSA form after loop interchange!"' failed.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash
backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: /home/llvm-trunk/bin/clang -c -O2 -mllvm
-enable-loopinterchange foo.c
1.      <eof> parser at end of file
2.      Per-module optimization passes
3.      Running pass 'CallGraph Pass Manager' on module 'foo.c'.
4.      Running pass 'Loop Pass Manager' on function '@fn1'
5.      Running pass 'Interchanges loops for cache reuse' on basic block
'%for.cond1.preheader'
...
...
...

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