[PATCH] D149323: [SCEV] Don't invalidate past dependency-breaking instructions

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added a comment.

Consider example:

  %sum = add i32 %x, %y
  %load_p= gep ptr %p, i32 %sum
  %load1 = load %i32 load_p
  
  if (%load_1 == %sum) {
    %load_2 = load %i32 load_p
    %sum_2 = add i32 %load_2, 2
  }


Here we can theoretically prove that SCEV for `%load_2` is `%x + %y` (same as `%sum`) and `%sum2 = %x + %y + 1`.

Now, imagine that we invalidate `%x`. With your patch, if I understand it correctly, `%sum_2` won't be invalidated.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D149323/new/

https://reviews.llvm.org/D149323