[PATCH] D25333: [LV] Avoid rounding errors for predicated instruction costs

[Matthew Simpson via llvm-commits]

mssimpso created this revision.
mssimpso added reviewers: anemet, mkuper, gilr.
mssimpso added subscribers: llvm-commits, mcrosier.
Herald added a subscriber: mzolotukhin.

This patch modifies the cost calculation of predicated instructions (div and rem) to avoid the accumulation of rounding errors due to multiple truncating integer divisions. The calculation for predicated stores will be addressed in a follow-on patch, since we currently don't scale the cost of predicated stores by block probability.


https://reviews.llvm.org/D25333

Files:
  lib/Transforms/Vectorize/LoopVectorize.cpp
  test/Transforms/LoopVectorize/AArch64/predication_costs.ll

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