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35167a94b8
We have several bug reports that could be characterized as "reducing scalarization", and this topic was also raised on llvm-dev recently: http://lists.llvm.org/pipermail/llvm-dev/2020-January/138157.html ...so I'm proposing that we deal with these patterns in a new, lightweight IR vector pass that runs before/after other vectorization passes. There are 4 alternate options that I can think of to deal with this kind of problem (and we've seen various attempts at all of these), but they all have flaws: InstCombine - can't happen without TTI, but we don't want target-specific folds there. SDAG - too late to assist other vectorization passes; TLI is not equipped for these kind of cost queries; limited to a single basic block. CGP - too late to assist other vectorization passes; would need to re-implement basic cleanups like CSE/instcombine. SLP - doesn't fit with existing transforms; limited to a single basic block. This initial patch/transform is based on existing code in AggressiveInstCombine: we walk backwards through the function looking for a pattern match. But we diverge from that cost-independent IR canonicalization pass by using TTI to decide if the vector alternative is profitable. We probably have at least 10 similar bug reports/patterns (binops, constants, inserts, cheap shuffles, etc) that would fit in this pass as follow-up enhancements. It's possible that we could iterate on a worklist to fix-point like InstCombine does, but it's safer to start with a most basic case and evolve from there, so I didn't try to do anything fancy with this initial implementation. Differential Revision: https://reviews.llvm.org/D73480
150 lines
4.3 KiB
C++
150 lines
4.3 KiB
C++
//===-- Vectorize.h - Vectorization Transformations -------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This header file defines prototypes for accessor functions that expose passes
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// in the Vectorize transformations library.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_VECTORIZE_H
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#define LLVM_TRANSFORMS_VECTORIZE_H
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namespace llvm {
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class BasicBlock;
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class Pass;
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//===----------------------------------------------------------------------===//
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/// Vectorize configuration.
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struct VectorizeConfig {
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//===--------------------------------------------------------------------===//
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// Target architecture related parameters
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/// The size of the native vector registers.
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unsigned VectorBits;
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/// Vectorize boolean values.
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bool VectorizeBools;
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/// Vectorize integer values.
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bool VectorizeInts;
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/// Vectorize floating-point values.
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bool VectorizeFloats;
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/// Vectorize pointer values.
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bool VectorizePointers;
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/// Vectorize casting (conversion) operations.
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bool VectorizeCasts;
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/// Vectorize floating-point math intrinsics.
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bool VectorizeMath;
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/// Vectorize bit intrinsics.
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bool VectorizeBitManipulations;
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/// Vectorize the fused-multiply-add intrinsic.
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bool VectorizeFMA;
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/// Vectorize select instructions.
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bool VectorizeSelect;
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/// Vectorize comparison instructions.
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bool VectorizeCmp;
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/// Vectorize getelementptr instructions.
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bool VectorizeGEP;
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/// Vectorize loads and stores.
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bool VectorizeMemOps;
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/// Only generate aligned loads and stores.
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bool AlignedOnly;
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//===--------------------------------------------------------------------===//
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// Misc parameters
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/// The required chain depth for vectorization.
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unsigned ReqChainDepth;
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/// The maximum search distance for instruction pairs.
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unsigned SearchLimit;
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/// The maximum number of candidate pairs with which to use a full
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/// cycle check.
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unsigned MaxCandPairsForCycleCheck;
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/// Replicating one element to a pair breaks the chain.
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bool SplatBreaksChain;
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/// The maximum number of pairable instructions per group.
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unsigned MaxInsts;
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/// The maximum number of candidate instruction pairs per group.
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unsigned MaxPairs;
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/// The maximum number of pairing iterations.
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unsigned MaxIter;
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/// Don't try to form odd-length vectors.
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bool Pow2LenOnly;
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/// Don't boost the chain-depth contribution of loads and stores.
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bool NoMemOpBoost;
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/// Use a fast instruction dependency analysis.
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bool FastDep;
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/// Initialize the VectorizeConfig from command line options.
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VectorizeConfig();
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};
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//===----------------------------------------------------------------------===//
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//
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// LoopVectorize - Create a loop vectorization pass.
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//
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Pass *createLoopVectorizePass();
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Pass *createLoopVectorizePass(bool InterleaveOnlyWhenForced,
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bool VectorizeOnlyWhenForced);
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//===----------------------------------------------------------------------===//
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//
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// SLPVectorizer - Create a bottom-up SLP vectorizer pass.
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//
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Pass *createSLPVectorizerPass();
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//===----------------------------------------------------------------------===//
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/// Vectorize the BasicBlock.
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///
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/// @param BB The BasicBlock to be vectorized
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/// @param P The current running pass, should require AliasAnalysis and
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/// ScalarEvolution. After the vectorization, AliasAnalysis,
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/// ScalarEvolution and CFG are preserved.
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///
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/// @return True if the BB is changed, false otherwise.
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///
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bool vectorizeBasicBlock(Pass *P, BasicBlock &BB,
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const VectorizeConfig &C = VectorizeConfig());
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//===----------------------------------------------------------------------===//
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//
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// LoadStoreVectorizer - Create vector loads and stores, but leave scalar
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// operations.
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//
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Pass *createLoadStoreVectorizerPass();
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//===----------------------------------------------------------------------===//
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//
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// Optimize partial vector operations using target cost models.
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//
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Pass *createVectorCombinePass();
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} // End llvm namespace
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#endif
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