[PATCH] D37121: [DivRemHoist] add a pass to move div/rem pairs into the same block (PR31028)

[Sanjay Patel via Phabricator via llvm-commits]

spatel updated this revision to Diff 114020.
spatel added a comment.

Patch updated:
As I was rummaging around in the cost models (realizing they're quite wrong for div/rem/mul in their own ways) and trying to bend them to express what I wanted...

I decided it would be better to just add a new TTI shim (hasDivRemOp()) to implement the behavior that I initially had when this was a CGP add-on. I realize we're at the edge of IR vs. backend transforms here, so let me know if this is wrong. Based on the existing hooks for things like masked ops, however, this doesn't look out of place to me.

I also figured it was best to just replace a non-hoistable rem instruction in-place and avoid getting into the inaccurate cost model mess to decide when hoisting would be the right thing to do. So now the i128 test for x86 shows that optimization instead of just bailing out. I think that's also the right thing to do for all targets that don't have HW divrem (everything in trunk besides x86?).


https://reviews.llvm.org/D37121

Files:
  include/llvm/Analysis/TargetTransformInfo.h
  include/llvm/Analysis/TargetTransformInfoImpl.h
  include/llvm/InitializePasses.h
  include/llvm/Transforms/Scalar.h
  include/llvm/Transforms/Scalar/DivRemHoist.h
  lib/Analysis/TargetTransformInfo.cpp
  lib/Passes/PassBuilder.cpp
  lib/Passes/PassRegistry.def
  lib/Target/X86/X86TargetTransformInfo.cpp
  lib/Target/X86/X86TargetTransformInfo.h
  lib/Transforms/IPO/PassManagerBuilder.cpp
  lib/Transforms/Scalar/CMakeLists.txt
  lib/Transforms/Scalar/DivRemHoist.cpp
  lib/Transforms/Scalar/Scalar.cpp
  test/Other/new-pm-defaults.ll
  test/Other/new-pm-thinlto-defaults.ll
  test/Transforms/DivRemHoist/div-rem-pairs.ll

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