[PATCH] D126533: [LAA] Relax pointer dependency with runtime pointer checks

[Igor Kirillov via Phabricator via llvm-commits]

igor.kirillov added a comment.

This patch actually also enables support for the cases where we have potentially conflicting accesses that have different strides (well invariant read is technically stride equal to zero). Here's one more real-live example:

   __attribute__((aligned(ALIGNMENT))) TYPE * const a = global_data.a;
   __attribute__((aligned(ALIGNMENT))) TYPE * const b = global_data.b;
   __attribute__((aligned(ALIGNMENT))) TYPE * const c = global_data.c;
   __attribute__((aligned(ALIGNMENT))) TYPE * const d = global_data.d;
  
  ...
  
  for (int i = 0; i < LEN/2; i++) {
    a[2*i] = c[i] * b[i] + d[i] * b[i] + c[i] * c[i] + d[i] * b[i] + d[i] * c[i];
  }

But we have to keep in mind that if we enable this feature then function `RuntimePointerChecking::groupChecks` will be running second time with `UseDependencies` equal to `false` and it will be emitting a lot of runtime check. There is a way to decrease that number by doing more accurate grouping and it can be implemented as follow-up patch.


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  https://reviews.llvm.org/D126533/new/

https://reviews.llvm.org/D126533