[all-commits] [llvm/llvm-project] 795d14: [NFCI][IndVars] rewriteLoopExitValues(): don't exp...

[Roman Lebedev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 795d142d237e0a06c136886a6dd9c49235c37295
      https://github.com/llvm/llvm-project/commit/795d142d237e0a06c136886a6dd9c49235c37295
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2021-08-30 (Mon, 30 Aug 2021)

  Changed paths:
    M llvm/lib/Transforms/Utils/LoopUtils.cpp

  Log Message:
  -----------
  [NFCI][IndVars] rewriteLoopExitValues(): don't expand SCEV's until needed

Previously, we'd expand *ALL* the SCEV's eagerly, because we needed to
check with `isValidRewrite()`, and discard bad rewrite candidates,
but now that we do not do that, we also don't need to always expand.

In particular, this avoids expanding potentially-huge SCEV's that we
would discard anyways because they are high-cost and we aren't
rewriting aggressively.