[PATCH] D43931: [LoopUnroll] Ignore ephemeral values when checking full unroll profitability.

[Andrei Elovikov via Phabricator via llvm-commits]

a.elovikov created this revision.
a.elovikov added reviewers: mzolotukhin, evstupac, sanjoy.

Before this patch call graph is like this in the LoopUnrollPass:

tryToUnrollLoop

  ApproximateLoopSize
    collectEphemeralValues
    /* Use collected ephemeral values */
  computeUnrollCount
    analyzeLoopUnrollCost
      /* Bail out from the analysis if loop contains CallInst */

This patch moves collection of the ephemeral values to the tryToUnrollLoop
function and passes the collected values into both ApproximateLoopsize (as
before) and additionally starts using them in analyzeLoopUnrollCost:

tryToUnrollLoop

  collectEphemeralValues
  ApproximateLoopSize(EphValues)
    /* Use EphValues */
  computeUnrollCount(EphValues)
    analyzeLoopUnrollCost(EphValues)
      /* Ignore ephemeral values - they don't contribute to the final cost */
      /* Bail out from the analysis if loop contains CallInst */


Repository:
  rL LLVM

https://reviews.llvm.org/D43931

Files:
  lib/Transforms/Scalar/LoopUnrollPass.cpp
  test/Transforms/LoopUnroll/complete_unroll_profitability_with_assume.ll

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