256 lines
11 KiB
C++
256 lines
11 KiB
C++
//===- VPlanUtils.h - VPlan-related utilities -------------------*- 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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#ifndef LLVM_TRANSFORMS_VECTORIZE_VPLANUTILS_H
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#define LLVM_TRANSFORMS_VECTORIZE_VPLANUTILS_H
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#include "VPlan.h"
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namespace llvm {
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class ScalarEvolution;
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class SCEV;
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} // namespace llvm
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namespace llvm {
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namespace vputils {
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/// Returns true if only the first lane of \p Def is used.
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bool onlyFirstLaneUsed(const VPValue *Def);
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/// Returns true if only the first part of \p Def is used.
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bool onlyFirstPartUsed(const VPValue *Def);
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/// Returns true if only scalar values of \p Def are used by all users.
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bool onlyScalarValuesUsed(const VPValue *Def);
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/// Get or create a VPValue that corresponds to the expansion of \p Expr. If \p
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/// Expr is a SCEVConstant or SCEVUnknown, return a VPValue wrapping the live-in
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/// value. Otherwise return a VPExpandSCEVRecipe to expand \p Expr. If \p Plan's
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/// pre-header already contains a recipe expanding \p Expr, return it. If not,
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/// create a new one.
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VPValue *getOrCreateVPValueForSCEVExpr(VPlan &Plan, const SCEV *Expr,
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ScalarEvolution &SE);
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/// Return the SCEV expression for \p V. Returns SCEVCouldNotCompute if no
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/// SCEV expression could be constructed.
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const SCEV *getSCEVExprForVPValue(VPValue *V, ScalarEvolution &SE);
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/// Returns true if \p VPV is a single scalar, either because it produces the
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/// same value for all lanes or only has its first lane used.
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inline bool isSingleScalar(const VPValue *VPV) {
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auto PreservesUniformity = [](unsigned Opcode) -> bool {
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if (Instruction::isBinaryOp(Opcode) || Instruction::isCast(Opcode))
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return true;
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switch (Opcode) {
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case Instruction::GetElementPtr:
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case Instruction::ICmp:
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case Instruction::FCmp:
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case VPInstruction::Broadcast:
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case VPInstruction::PtrAdd:
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return true;
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default:
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return false;
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}
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};
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// A live-in must be uniform across the scope of VPlan.
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if (VPV->isLiveIn())
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return true;
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if (auto *Rep = dyn_cast<VPReplicateRecipe>(VPV)) {
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const VPRegionBlock *RegionOfR = Rep->getParent()->getParent();
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// Don't consider recipes in replicate regions as uniform yet; their first
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// lane cannot be accessed when executing the replicate region for other
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// lanes.
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if (RegionOfR && RegionOfR->isReplicator())
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return false;
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return Rep->isSingleScalar() || (PreservesUniformity(Rep->getOpcode()) &&
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all_of(Rep->operands(), isSingleScalar));
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}
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if (isa<VPWidenGEPRecipe, VPDerivedIVRecipe, VPBlendRecipe,
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VPWidenSelectRecipe>(VPV))
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return all_of(VPV->getDefiningRecipe()->operands(), isSingleScalar);
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if (auto *WidenR = dyn_cast<VPWidenRecipe>(VPV)) {
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return PreservesUniformity(WidenR->getOpcode()) &&
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all_of(WidenR->operands(), isSingleScalar);
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}
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if (auto *VPI = dyn_cast<VPInstruction>(VPV))
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return VPI->isSingleScalar() || VPI->isVectorToScalar() ||
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(PreservesUniformity(VPI->getOpcode()) &&
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all_of(VPI->operands(), isSingleScalar));
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// VPExpandSCEVRecipes must be placed in the entry and are alway uniform.
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return isa<VPExpandSCEVRecipe>(VPV);
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}
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/// Return true if \p V is a header mask in \p Plan.
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bool isHeaderMask(const VPValue *V, VPlan &Plan);
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/// Checks if \p V is uniform across all VF lanes and UF parts. It is considered
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/// as such if it is either loop invariant (defined outside the vector region)
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/// or its operand is known to be uniform across all VFs and UFs (e.g.
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/// VPDerivedIV or VPCanonicalIVPHI).
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bool isUniformAcrossVFsAndUFs(VPValue *V);
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/// Returns the header block of the first, top-level loop, or null if none
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/// exist.
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VPBasicBlock *getFirstLoopHeader(VPlan &Plan, VPDominatorTree &VPDT);
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} // namespace vputils
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//===----------------------------------------------------------------------===//
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// Utilities for modifying predecessors and successors of VPlan blocks.
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//===----------------------------------------------------------------------===//
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/// Class that provides utilities for VPBlockBases in VPlan.
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class VPBlockUtils {
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public:
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VPBlockUtils() = delete;
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/// Insert disconnected VPBlockBase \p NewBlock after \p BlockPtr. Add \p
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/// NewBlock as successor of \p BlockPtr and \p BlockPtr as predecessor of \p
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/// NewBlock, and propagate \p BlockPtr parent to \p NewBlock. \p BlockPtr's
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/// successors are moved from \p BlockPtr to \p NewBlock. \p NewBlock must
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/// have neither successors nor predecessors.
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static void insertBlockAfter(VPBlockBase *NewBlock, VPBlockBase *BlockPtr) {
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assert(NewBlock->getSuccessors().empty() &&
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NewBlock->getPredecessors().empty() &&
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"Can't insert new block with predecessors or successors.");
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NewBlock->setParent(BlockPtr->getParent());
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SmallVector<VPBlockBase *> Succs(BlockPtr->successors());
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for (VPBlockBase *Succ : Succs) {
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Succ->replacePredecessor(BlockPtr, NewBlock);
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NewBlock->appendSuccessor(Succ);
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}
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BlockPtr->clearSuccessors();
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connectBlocks(BlockPtr, NewBlock);
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}
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/// Insert disconnected block \p NewBlock before \p Blockptr. First
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/// disconnects all predecessors of \p BlockPtr and connects them to \p
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/// NewBlock. Add \p NewBlock as predecessor of \p BlockPtr and \p BlockPtr as
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/// successor of \p NewBlock.
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static void insertBlockBefore(VPBlockBase *NewBlock, VPBlockBase *BlockPtr) {
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assert(NewBlock->getSuccessors().empty() &&
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NewBlock->getPredecessors().empty() &&
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"Can't insert new block with predecessors or successors.");
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NewBlock->setParent(BlockPtr->getParent());
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for (VPBlockBase *Pred : to_vector(BlockPtr->predecessors())) {
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Pred->replaceSuccessor(BlockPtr, NewBlock);
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NewBlock->appendPredecessor(Pred);
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}
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BlockPtr->clearPredecessors();
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connectBlocks(NewBlock, BlockPtr);
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}
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/// Insert disconnected VPBlockBases \p IfTrue and \p IfFalse after \p
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/// BlockPtr. Add \p IfTrue and \p IfFalse as succesors of \p BlockPtr and \p
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/// BlockPtr as predecessor of \p IfTrue and \p IfFalse. Propagate \p BlockPtr
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/// parent to \p IfTrue and \p IfFalse. \p BlockPtr must have no successors
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/// and \p IfTrue and \p IfFalse must have neither successors nor
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/// predecessors.
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static void insertTwoBlocksAfter(VPBlockBase *IfTrue, VPBlockBase *IfFalse,
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VPBlockBase *BlockPtr) {
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assert(IfTrue->getSuccessors().empty() &&
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"Can't insert IfTrue with successors.");
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assert(IfFalse->getSuccessors().empty() &&
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"Can't insert IfFalse with successors.");
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BlockPtr->setTwoSuccessors(IfTrue, IfFalse);
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IfTrue->setPredecessors({BlockPtr});
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IfFalse->setPredecessors({BlockPtr});
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IfTrue->setParent(BlockPtr->getParent());
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IfFalse->setParent(BlockPtr->getParent());
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}
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/// Connect VPBlockBases \p From and \p To bi-directionally. If \p PredIdx is
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/// -1, append \p From to the predecessors of \p To, otherwise set \p To's
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/// predecessor at \p PredIdx to \p From. If \p SuccIdx is -1, append \p To to
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/// the successors of \p From, otherwise set \p From's successor at \p SuccIdx
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/// to \p To. Both VPBlockBases must have the same parent, which can be null.
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/// Both VPBlockBases can be already connected to other VPBlockBases.
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static void connectBlocks(VPBlockBase *From, VPBlockBase *To,
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unsigned PredIdx = -1u, unsigned SuccIdx = -1u) {
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assert((From->getParent() == To->getParent()) &&
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"Can't connect two block with different parents");
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assert((SuccIdx != -1u || From->getNumSuccessors() < 2) &&
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"Blocks can't have more than two successors.");
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if (SuccIdx == -1u)
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From->appendSuccessor(To);
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else
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From->getSuccessors()[SuccIdx] = To;
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if (PredIdx == -1u)
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To->appendPredecessor(From);
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else
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To->getPredecessors()[PredIdx] = From;
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}
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/// Disconnect VPBlockBases \p From and \p To bi-directionally. Remove \p To
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/// from the successors of \p From and \p From from the predecessors of \p To.
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static void disconnectBlocks(VPBlockBase *From, VPBlockBase *To) {
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assert(To && "Successor to disconnect is null.");
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From->removeSuccessor(To);
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To->removePredecessor(From);
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}
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/// Reassociate all the blocks connected to \p Old so that they now point to
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/// \p New.
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static void reassociateBlocks(VPBlockBase *Old, VPBlockBase *New) {
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for (auto *Pred : to_vector(Old->getPredecessors()))
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Pred->replaceSuccessor(Old, New);
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for (auto *Succ : to_vector(Old->getSuccessors()))
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Succ->replacePredecessor(Old, New);
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New->setPredecessors(Old->getPredecessors());
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New->setSuccessors(Old->getSuccessors());
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Old->clearPredecessors();
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Old->clearSuccessors();
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}
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/// Return an iterator range over \p Range which only includes \p BlockTy
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/// blocks. The accesses are casted to \p BlockTy.
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template <typename BlockTy, typename T>
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static auto blocksOnly(const T &Range) {
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// Create BaseTy with correct const-ness based on BlockTy.
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using BaseTy = std::conditional_t<std::is_const<BlockTy>::value,
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const VPBlockBase, VPBlockBase>;
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// We need to first create an iterator range over (const) BlocktTy & instead
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// of (const) BlockTy * for filter_range to work properly.
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auto Mapped =
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map_range(Range, [](BaseTy *Block) -> BaseTy & { return *Block; });
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auto Filter = make_filter_range(
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Mapped, [](BaseTy &Block) { return isa<BlockTy>(&Block); });
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return map_range(Filter, [](BaseTy &Block) -> BlockTy * {
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return cast<BlockTy>(&Block);
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});
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}
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/// Inserts \p BlockPtr on the edge between \p From and \p To. That is, update
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/// \p From's successor to \p To to point to \p BlockPtr and \p To's
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/// predecessor from \p From to \p BlockPtr. \p From and \p To are added to \p
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/// BlockPtr's predecessors and successors respectively. There must be a
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/// single edge between \p From and \p To.
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static void insertOnEdge(VPBlockBase *From, VPBlockBase *To,
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VPBlockBase *BlockPtr) {
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unsigned SuccIdx = From->getIndexForSuccessor(To);
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unsigned PredIx = To->getIndexForPredecessor(From);
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VPBlockUtils::connectBlocks(From, BlockPtr, -1, SuccIdx);
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VPBlockUtils::connectBlocks(BlockPtr, To, PredIx, -1);
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}
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/// Returns true if \p VPB is a loop header, based on regions or \p VPDT in
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/// their absence.
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static bool isHeader(const VPBlockBase *VPB, const VPDominatorTree &VPDT);
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/// Returns true if \p VPB is a loop latch, using isHeader().
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static bool isLatch(const VPBlockBase *VPB, const VPDominatorTree &VPDT);
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};
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} // namespace llvm
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#endif
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