[PATCH] D66106: [LV] fold-tail predication should be respected even with assume_safety

[Dorit Nuzman via Phabricator via llvm-commits]

dorit created this revision.
dorit added reviewers: Ayal, hsaito, fhahn.
dorit added a project: LLVM.
Herald added a subscriber: rkruppe.

assume_safety implies that loads under "if's" can be safely executed speculatively (unguarded, unmasked). However this assumption holds only for the original user "if's", not those introduced by the compiler, such as the fold-tail "if" that guards us from loading beyond the original loop trip-count. Currently the combination of fold-tail and assume-safety pragmas results in ignoring the fold-tail predicate that guards the loads, generating unmasked loads.  This patch fixes this behavior.


https://reviews.llvm.org/D66106

Files:
  include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
  lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
  lib/Transforms/Vectorize/LoopVectorize.cpp
  test/Transforms/LoopVectorize/X86/tail_folding_and_assume_safety.ll
  test/Transforms/LoopVectorize/X86/vect.omp.force.small-tc.ll

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