[all-commits] [llvm/llvm-project] c7496c: [LV] Use SCEV to check if minimum iteration check ...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c7496cebac047665dbe9460d536c7654bc643a43
      https://github.com/llvm/llvm-project/commit/c7496cebac047665dbe9460d536c7654bc643a43
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2024-10-18 (Fri, 18 Oct 2024)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/test/Transforms/LoopVectorize/AArch64/eliminate-tail-predication.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/masked-call.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/pr60831-sve-inv-store-crash.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/sve-tail-folding.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/wider-VF-for-callinst.ll
    M llvm/test/Transforms/LoopVectorize/if-reduction.ll
    M llvm/test/Transforms/LoopVectorize/version-stride-with-integer-casts.ll

  Log Message:
  -----------
  [LV] Use SCEV to check if minimum iteration check is known. (#111310)

Use SCEV to check if the minimum iteration check (TC < Step) is known to
be false.

This is a first step towards addressing
https://github.com/llvm/llvm-project/issues/111098. To catch the exact
case from the issue, we need to do extra work to make sure the wrap
flags on the shl are preserved and used by SCEV.

Note that skeleton creation will be gradually moved to VPlan and this
simplification should be done as VPlan transform eventually. The current
plan is to move skeleton creation to VPlan starting from parts closest
to the parts already created by VPlan, starting with induction resume
value creation (started with
https://github.com/llvm/llvm-project/pull/110577), then memory and SCEV
checks and finally minimum iteration checks.

PR: https://github.com/llvm/llvm-project/pull/111310



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