[PATCH] D92645: [X86] Add X86ISD::SUBV_BROADCAST_LOAD and begin removing X86ISD::SUBV_BROADCAST (PR38969)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: craig.topper, spatel, pengfei.
Herald added a subscriber: hiraditya.
RKSimon requested review of this revision.
Herald added a project: LLVM.

Subvector broadcasts are only load instructions, yet X86ISD::SUBV_BROADCAST treats them more generally, requiring a lot of fallback tablegen patterns.

This initial patch replaces constant vector lowering inside lowerBuildVectorAsBroadcast with direct X86ISD::SUBV_BROADCAST_LOAD loads which helps us merge a number of equivalent loads/broadcasts.

As well as general plumbing/analysis additions for SUBV_BROADCAST_LOAD, I needed to wrap SelectionDAG::makeEquivalentMemoryOrdering so it can handle result chains from non generic LoadSDNode nodes.

Later patches will continue to replace X86ISD::SUBV_BROADCAST usage.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92645

Files:
  llvm/include/llvm/CodeGen/SelectionDAG.h
  llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/lib/Target/X86/X86ISelLowering.h
  llvm/lib/Target/X86/X86InstrAVX512.td
  llvm/lib/Target/X86/X86InstrFragmentsSIMD.td
  llvm/lib/Target/X86/X86InstrSSE.td
  llvm/test/CodeGen/X86/broadcast-elm-cross-splat-vec.ll
  llvm/test/CodeGen/X86/subvector-broadcast.ll
  llvm/test/CodeGen/X86/vector-trunc.ll

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