[PATCH] D86093: [X86][AVX] Lower v16i8/v8i16 shuffles using VTRUNC/TRUNCATE

[Simon Pilgrim via Phabricator via llvm-commits]

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

This patch extends the existing lowerShuffleWithVPMOV with a lowerShuffleWithVTRUNC wrapper that handles basic unary/binary shuffles that can be lowered either as a pure ISD::TRUNCATE or a X86ISD::VTRUNC (with undef/zero values in the remaining upper elements).

For binary shuffles we concat the sources together into a single 256-bit source vector. To avoid regressions we perform this after we've tried to lower with PACKS/PACKUS which typically does a cleaner job than a concat.

For non-AVX512VL cases we have to canonicalize VTRUNC cases to use a 512-bit source vectors (inserting undefs/zeros in the upper elements as necessary), truncate and then (possibly) extract the 128-bit result.

This should address the last regressions in D66004 <https://reviews.llvm.org/D66004>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D86093

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/avx512-trunc.ll
  llvm/test/CodeGen/X86/avx512-vec-cmp.ll
  llvm/test/CodeGen/X86/madd.ll
  llvm/test/CodeGen/X86/masked_store_trunc.ll
  llvm/test/CodeGen/X86/pmaddubsw.ll
  llvm/test/CodeGen/X86/shuffle-vs-trunc-128.ll
  llvm/test/CodeGen/X86/shuffle-vs-trunc-256.ll
  llvm/test/CodeGen/X86/shuffle-vs-trunc-512.ll
  llvm/test/CodeGen/X86/vec-strict-fptoint-128.ll
  llvm/test/CodeGen/X86/vec_fp_to_int.ll
  llvm/test/CodeGen/X86/vector-rotate-128.ll
  llvm/test/CodeGen/X86/vector-trunc.ll
  llvm/test/CodeGen/X86/widen_mul.ll
  llvm/test/CodeGen/X86/x86-interleaved-access.ll

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