[all-commits] [llvm/llvm-project] 57bb47: [Pass Manager] remove EarlyCSE as clean-up for Vec...

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  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 57bb4787d72f1ae64f877b05c98d506602ac5958
      https://github.com/llvm/llvm-project/commit/57bb4787d72f1ae64f877b05c98d506602ac5958
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2020-05-24 (Sun, 24 May 2020)

  Changed paths:
    M llvm/lib/Passes/PassBuilder.cpp
    M llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
    M llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
    M llvm/test/Other/new-pm-defaults.ll
    M llvm/test/Other/new-pm-thinlto-defaults.ll
    M llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
    M llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
    M llvm/test/Other/opt-O2-pipeline.ll
    M llvm/test/Other/opt-O3-pipeline.ll
    M llvm/test/Other/opt-Os-pipeline.ll

  Log Message:
  -----------
  [Pass Manager] remove EarlyCSE as clean-up for VectorCombine

EarlyCSE was added with D75145, but the motivating test is
not regressed by removing the extra pass now. That might be
because VectorCombine altered the way it processes instructions,
or it might be from (re)moving VectorCombine in the pipeline.

The extra round of EarlyCSE appears to cost approximately
0.26% in compile-time as discussed in D80236, so we need some
evidence to justify its inclusion here, but we do not have
that (yet).

I suspect that between SLP and VectorCombine, we are creating
patterns that InstCombine and/or codegen are not prepared for,
but we will need to reduce those examples and include them as
PhaseOrdering and/or test-suite benchmarks.