[llvm] [SLP] NFC: Simplify CandidateVFs initialization (PR #144882)
Sander de Smalen via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 19 04:51:59 PDT 2025
https://github.com/sdesmalen-arm created https://github.com/llvm/llvm-project/pull/144882
Also adds a comment to clarify the meaning of MaxRegVF.
>From ad6f2775cb2cb97dd822c229a89103f37761d35c Mon Sep 17 00:00:00 2001
From: Sander de Smalen <sander.desmalen at arm.com>
Date: Thu, 19 Jun 2025 11:02:59 +0000
Subject: [PATCH] [SLP] NFC: Simplify CandidateVFs initialization
Also adds a comment to clarify the meaning of MaxRegVF.
---
llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 4551a365a6967..750c93a439c16 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -21198,7 +21198,11 @@ bool SLPVectorizerPass::vectorizeStores(
}
}
+ // MaxRegVF represents the number of instructions (scalar, or vector in
+ // case of revec) that can be vectorized to naturally fit in a vector
+ // register.
unsigned MaxRegVF = MaxVF;
+
MaxVF = std::min<unsigned>(MaxVF, bit_floor(Operands.size()));
if (MaxVF < MinVF) {
LLVM_DEBUG(dbgs() << "SLP: Vectorization infeasible as MaxVF (" << MaxVF
@@ -21207,13 +21211,11 @@ bool SLPVectorizerPass::vectorizeStores(
continue;
}
- unsigned Sz = 1 + Log2_32(MaxVF) - Log2_32(MinVF);
- SmallVector<unsigned> CandidateVFs(Sz + (NonPowerOf2VF > 0 ? 1 : 0));
- unsigned Size = MinVF;
- for (unsigned &VF : reverse(CandidateVFs)) {
- VF = Size > MaxVF ? NonPowerOf2VF : Size;
- Size *= 2;
- }
+ SmallVector<unsigned> CandidateVFs;
+ for (unsigned VF = std::max(MaxVF, NonPowerOf2VF); VF >= MinVF;
+ VF = divideCeil(VF, 2))
+ CandidateVFs.push_back(VF);
+
unsigned End = Operands.size();
unsigned Repeat = 0;
constexpr unsigned MaxAttempts = 4;
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