[PATCH] D106058: [DAG] Fold select(cond,binop(x,y),binop(x,z)) -> binop(x,select(cond,y,z))

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: spatel, lebedev.ri, jholewinski, jlebar, craig.topper.
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Similar to the folds performed in InstCombinerImpl::foldSelectOpOp, this attempts to push a select further up to help merge a pair of binops.

I'm primarily interested in select(cond,add(x,y),add(x,z)) folds to help expose pointer math (see https://bugs.llvm.org/show_bug.cgi?id=51069 etc.) but I've tried to use the more generic isBinOp() - this affects some NVPTX tests, which I think benefit (and would have been combined the same way in InstCombine) but if its affecting what is supposed to be tested then I'm happy to change the tests, restrict this to ISD::ADD or move it inside X86, if people think this is too generic.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D106058

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/NVPTX/fast-math.ll
  llvm/test/CodeGen/X86/select.ll

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