[llvm-bugs] [Bug 31391] New: [LoopIdiomRecognition] Add support for run-time checks for memory disambiguation.

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https://llvm.org/bugs/show_bug.cgi?id=31391

            Bug ID: 31391
           Summary: [LoopIdiomRecognition] Add support for run-time checks
                    for memory disambiguation.
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: Loop Optimizer
          Assignee: unassignedbugs at nondot.org
          Reporter: mcrosier at codeaurora.org
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Currently, the loop idiom recognition pass is unable convert the below test
case into a memcpy because runtime checks are required to ensure 'a' and 'b'
don't alias:

void test(unsigned N, double *src, double *dst) {
  for (int i = 0; i < N; ++i)
    dst[i] = src[i];
}

As an aside, once D27677 (https://reviews.llvm.org/D27677) lands the LV will
vectorize this loop when targeting AArch64 by inserting the necessary runtime
checks.  Regardless, we should consider having this feature in the LIR pass
because it will catch cases in loop that the LV can't vectorize.

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