[all-commits] [llvm/llvm-project] 38ad0d: [X86] combineEXTRACT_SUBVECTOR - extract from a la...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 38ad0df38c91d8b6655664f205810fb5a7a86b4b
      https://github.com/llvm/llvm-project/commit/38ad0df38c91d8b6655664f205810fb5a7a86b4b
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2025-03-26 (Wed, 26 Mar 2025)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/vector-interleaved-store-i16-stride-6.ll
    M llvm/test/CodeGen/X86/vector-interleaved-store-i8-stride-3.ll
    M llvm/test/CodeGen/X86/vector-interleaved-store-i8-stride-6.ll
    M llvm/test/CodeGen/X86/widen_fadd.ll
    M llvm/test/CodeGen/X86/widen_fdiv.ll
    M llvm/test/CodeGen/X86/widen_fmul.ll
    M llvm/test/CodeGen/X86/widen_fsub.ll
    M llvm/test/CodeGen/X86/x86-interleaved-access.ll

  Log Message:
  -----------
  [X86] combineEXTRACT_SUBVECTOR - extract from a larger subvector insertion (#132950)

Fold EXTRACT_SUBVECTOR(INSERT_SUBVECTOR(SRC,SUB,C1),C2) ->
INSERT_SUBVECTOR(EXTRACT_SUBVECTOR(SRC,C2),SUB,C1-C2)

This extends the existing fold which required the extract/insert
subvector indices to match - now it will always extract as long as the
original inserted subvector is entirely contained within the extraction.

Helps avoid unnecessary use of 512-bit vectors, and improves the chance
of concatenation folds.



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