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0059dd4dd1
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220690 91177308-0d34-0410-b5e6-96231b3b80d8
519 lines
17 KiB
C++
519 lines
17 KiB
C++
//===-- RegAllocPBQP.h ------------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the PBQPBuilder interface, for classes which build PBQP
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// instances to represent register allocation problems, and the RegAllocPBQP
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// interface.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_REGALLOCPBQP_H
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#define LLVM_CODEGEN_REGALLOCPBQP_H
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/PBQPRAConstraint.h"
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#include "llvm/CodeGen/PBQP/CostAllocator.h"
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#include "llvm/CodeGen/PBQP/ReductionRules.h"
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#include "llvm/Support/ErrorHandling.h"
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namespace llvm {
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namespace PBQP {
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namespace RegAlloc {
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/// @brief Spill option index.
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inline unsigned getSpillOptionIdx() { return 0; }
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/// \brief Metadata to speed allocatability test.
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///
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/// Keeps track of the number of infinities in each row and column.
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class MatrixMetadata {
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private:
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MatrixMetadata(const MatrixMetadata&);
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void operator=(const MatrixMetadata&);
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public:
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MatrixMetadata(const Matrix& M)
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: WorstRow(0), WorstCol(0),
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UnsafeRows(new bool[M.getRows() - 1]()),
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UnsafeCols(new bool[M.getCols() - 1]()) {
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unsigned* ColCounts = new unsigned[M.getCols() - 1]();
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for (unsigned i = 1; i < M.getRows(); ++i) {
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unsigned RowCount = 0;
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for (unsigned j = 1; j < M.getCols(); ++j) {
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if (M[i][j] == std::numeric_limits<PBQPNum>::infinity()) {
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++RowCount;
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++ColCounts[j - 1];
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UnsafeRows[i - 1] = true;
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UnsafeCols[j - 1] = true;
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}
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}
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WorstRow = std::max(WorstRow, RowCount);
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}
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unsigned WorstColCountForCurRow =
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*std::max_element(ColCounts, ColCounts + M.getCols() - 1);
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WorstCol = std::max(WorstCol, WorstColCountForCurRow);
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delete[] ColCounts;
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}
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unsigned getWorstRow() const { return WorstRow; }
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unsigned getWorstCol() const { return WorstCol; }
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const bool* getUnsafeRows() const { return UnsafeRows.get(); }
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const bool* getUnsafeCols() const { return UnsafeCols.get(); }
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private:
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unsigned WorstRow, WorstCol;
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std::unique_ptr<bool[]> UnsafeRows;
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std::unique_ptr<bool[]> UnsafeCols;
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};
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/// \brief Holds a vector of the allowed physical regs for a vreg.
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class AllowedRegVector {
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friend hash_code hash_value(const AllowedRegVector &);
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public:
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AllowedRegVector() : NumOpts(0), Opts(nullptr) {}
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AllowedRegVector(const std::vector<unsigned> &OptVec)
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: NumOpts(OptVec.size()), Opts(new unsigned[NumOpts]) {
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std::copy(OptVec.begin(), OptVec.end(), Opts.get());
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}
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AllowedRegVector(const AllowedRegVector &Other)
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: NumOpts(Other.NumOpts), Opts(new unsigned[NumOpts]) {
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std::copy(Other.Opts.get(), Other.Opts.get() + NumOpts, Opts.get());
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}
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AllowedRegVector(AllowedRegVector &&Other)
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: NumOpts(std::move(Other.NumOpts)), Opts(std::move(Other.Opts)) {}
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AllowedRegVector& operator=(const AllowedRegVector &Other) {
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NumOpts = Other.NumOpts;
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Opts.reset(new unsigned[NumOpts]);
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std::copy(Other.Opts.get(), Other.Opts.get() + NumOpts, Opts.get());
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return *this;
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}
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AllowedRegVector& operator=(AllowedRegVector &&Other) {
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NumOpts = std::move(Other.NumOpts);
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Opts = std::move(Other.Opts);
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return *this;
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}
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unsigned size() const { return NumOpts; }
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unsigned operator[](size_t I) const { return Opts[I]; }
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bool operator==(const AllowedRegVector &Other) const {
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if (NumOpts != Other.NumOpts)
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return false;
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return std::equal(Opts.get(), Opts.get() + NumOpts, Other.Opts.get());
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}
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bool operator!=(const AllowedRegVector &Other) const {
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return !(*this == Other);
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}
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private:
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unsigned NumOpts;
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std::unique_ptr<unsigned[]> Opts;
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};
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inline hash_code hash_value(const AllowedRegVector &OptRegs) {
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unsigned *OStart = OptRegs.Opts.get();
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unsigned *OEnd = OptRegs.Opts.get() + OptRegs.NumOpts;
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return hash_combine(OptRegs.NumOpts,
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hash_combine_range(OStart, OEnd));
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}
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/// \brief Holds graph-level metadata relevent to PBQP RA problems.
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class GraphMetadata {
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private:
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typedef ValuePool<AllowedRegVector> AllowedRegVecPool;
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public:
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typedef AllowedRegVecPool::PoolRef AllowedRegVecRef;
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GraphMetadata(MachineFunction &MF,
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LiveIntervals &LIS,
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MachineBlockFrequencyInfo &MBFI)
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: MF(MF), LIS(LIS), MBFI(MBFI) {}
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MachineFunction &MF;
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LiveIntervals &LIS;
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MachineBlockFrequencyInfo &MBFI;
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void setNodeIdForVReg(unsigned VReg, GraphBase::NodeId NId) {
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VRegToNodeId[VReg] = NId;
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}
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GraphBase::NodeId getNodeIdForVReg(unsigned VReg) const {
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auto VRegItr = VRegToNodeId.find(VReg);
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if (VRegItr == VRegToNodeId.end())
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return GraphBase::invalidNodeId();
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return VRegItr->second;
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}
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void eraseNodeIdForVReg(unsigned VReg) {
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VRegToNodeId.erase(VReg);
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}
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AllowedRegVecRef getAllowedRegs(AllowedRegVector Allowed) {
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return AllowedRegVecs.getValue(std::move(Allowed));
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}
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private:
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DenseMap<unsigned, GraphBase::NodeId> VRegToNodeId;
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AllowedRegVecPool AllowedRegVecs;
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};
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/// \brief Holds solver state and other metadata relevant to each PBQP RA node.
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class NodeMetadata {
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public:
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typedef RegAlloc::AllowedRegVector AllowedRegVector;
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typedef enum { Unprocessed,
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OptimallyReducible,
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ConservativelyAllocatable,
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NotProvablyAllocatable } ReductionState;
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NodeMetadata()
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: RS(Unprocessed), NumOpts(0), DeniedOpts(0), OptUnsafeEdges(nullptr),
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VReg(0) {}
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// FIXME: Re-implementing default behavior to work around MSVC. Remove once
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// MSVC synthesizes move constructors properly.
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NodeMetadata(const NodeMetadata &Other)
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: RS(Other.RS), NumOpts(Other.NumOpts), DeniedOpts(Other.DeniedOpts),
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OptUnsafeEdges(new unsigned[NumOpts]), VReg(Other.VReg),
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AllowedRegs(Other.AllowedRegs) {
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std::copy(&Other.OptUnsafeEdges[0], &Other.OptUnsafeEdges[NumOpts],
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&OptUnsafeEdges[0]);
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}
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// FIXME: Re-implementing default behavior to work around MSVC. Remove once
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// MSVC synthesizes move constructors properly.
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NodeMetadata(NodeMetadata &&Other)
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: RS(Other.RS), NumOpts(Other.NumOpts), DeniedOpts(Other.DeniedOpts),
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OptUnsafeEdges(std::move(Other.OptUnsafeEdges)), VReg(Other.VReg),
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AllowedRegs(std::move(Other.AllowedRegs)) {}
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// FIXME: Re-implementing default behavior to work around MSVC. Remove once
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// MSVC synthesizes move constructors properly.
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NodeMetadata& operator=(const NodeMetadata &Other) {
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RS = Other.RS;
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NumOpts = Other.NumOpts;
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DeniedOpts = Other.DeniedOpts;
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OptUnsafeEdges.reset(new unsigned[NumOpts]);
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std::copy(Other.OptUnsafeEdges.get(), Other.OptUnsafeEdges.get() + NumOpts,
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OptUnsafeEdges.get());
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VReg = Other.VReg;
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AllowedRegs = Other.AllowedRegs;
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return *this;
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}
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// FIXME: Re-implementing default behavior to work around MSVC. Remove once
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// MSVC synthesizes move constructors properly.
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NodeMetadata& operator=(NodeMetadata &&Other) {
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RS = Other.RS;
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NumOpts = Other.NumOpts;
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DeniedOpts = Other.DeniedOpts;
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OptUnsafeEdges = std::move(Other.OptUnsafeEdges);
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VReg = Other.VReg;
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AllowedRegs = std::move(Other.AllowedRegs);
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return *this;
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}
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void setVReg(unsigned VReg) { this->VReg = VReg; }
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unsigned getVReg() const { return VReg; }
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void setAllowedRegs(GraphMetadata::AllowedRegVecRef AllowedRegs) {
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this->AllowedRegs = std::move(AllowedRegs);
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}
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const AllowedRegVector& getAllowedRegs() const { return *AllowedRegs; }
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void setup(const Vector& Costs) {
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NumOpts = Costs.getLength() - 1;
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OptUnsafeEdges = std::unique_ptr<unsigned[]>(new unsigned[NumOpts]());
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}
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ReductionState getReductionState() const { return RS; }
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void setReductionState(ReductionState RS) { this->RS = RS; }
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void handleAddEdge(const MatrixMetadata& MD, bool Transpose) {
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DeniedOpts += Transpose ? MD.getWorstCol() : MD.getWorstRow();
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const bool* UnsafeOpts =
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Transpose ? MD.getUnsafeCols() : MD.getUnsafeRows();
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for (unsigned i = 0; i < NumOpts; ++i)
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OptUnsafeEdges[i] += UnsafeOpts[i];
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}
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void handleRemoveEdge(const MatrixMetadata& MD, bool Transpose) {
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DeniedOpts -= Transpose ? MD.getWorstCol() : MD.getWorstRow();
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const bool* UnsafeOpts =
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Transpose ? MD.getUnsafeCols() : MD.getUnsafeRows();
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for (unsigned i = 0; i < NumOpts; ++i)
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OptUnsafeEdges[i] -= UnsafeOpts[i];
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}
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bool isConservativelyAllocatable() const {
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return (DeniedOpts < NumOpts) ||
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(std::find(&OptUnsafeEdges[0], &OptUnsafeEdges[NumOpts], 0) !=
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&OptUnsafeEdges[NumOpts]);
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}
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private:
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ReductionState RS;
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unsigned NumOpts;
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unsigned DeniedOpts;
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std::unique_ptr<unsigned[]> OptUnsafeEdges;
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unsigned VReg;
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GraphMetadata::AllowedRegVecRef AllowedRegs;
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};
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class RegAllocSolverImpl {
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private:
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typedef MDMatrix<MatrixMetadata> RAMatrix;
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public:
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typedef PBQP::Vector RawVector;
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typedef PBQP::Matrix RawMatrix;
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typedef PBQP::Vector Vector;
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typedef RAMatrix Matrix;
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typedef PBQP::PoolCostAllocator<Vector, Matrix> CostAllocator;
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typedef GraphBase::NodeId NodeId;
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typedef GraphBase::EdgeId EdgeId;
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typedef RegAlloc::NodeMetadata NodeMetadata;
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struct EdgeMetadata { };
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typedef RegAlloc::GraphMetadata GraphMetadata;
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typedef PBQP::Graph<RegAllocSolverImpl> Graph;
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RegAllocSolverImpl(Graph &G) : G(G) {}
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Solution solve() {
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G.setSolver(*this);
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Solution S;
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setup();
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S = backpropagate(G, reduce());
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G.unsetSolver();
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return S;
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}
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void handleAddNode(NodeId NId) {
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G.getNodeMetadata(NId).setup(G.getNodeCosts(NId));
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}
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void handleRemoveNode(NodeId NId) {}
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void handleSetNodeCosts(NodeId NId, const Vector& newCosts) {}
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void handleAddEdge(EdgeId EId) {
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handleReconnectEdge(EId, G.getEdgeNode1Id(EId));
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handleReconnectEdge(EId, G.getEdgeNode2Id(EId));
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}
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void handleRemoveEdge(EdgeId EId) {
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handleDisconnectEdge(EId, G.getEdgeNode1Id(EId));
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handleDisconnectEdge(EId, G.getEdgeNode2Id(EId));
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}
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void handleDisconnectEdge(EdgeId EId, NodeId NId) {
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NodeMetadata& NMd = G.getNodeMetadata(NId);
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const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
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NMd.handleRemoveEdge(MMd, NId == G.getEdgeNode2Id(EId));
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if (G.getNodeDegree(NId) == 3) {
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// This node is becoming optimally reducible.
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moveToOptimallyReducibleNodes(NId);
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} else if (NMd.getReductionState() ==
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NodeMetadata::NotProvablyAllocatable &&
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NMd.isConservativelyAllocatable()) {
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// This node just became conservatively allocatable.
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moveToConservativelyAllocatableNodes(NId);
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}
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}
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void handleReconnectEdge(EdgeId EId, NodeId NId) {
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NodeMetadata& NMd = G.getNodeMetadata(NId);
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const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
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NMd.handleAddEdge(MMd, NId == G.getEdgeNode2Id(EId));
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}
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void handleSetEdgeCosts(EdgeId EId, const Matrix& NewCosts) {
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handleRemoveEdge(EId);
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NodeId N1Id = G.getEdgeNode1Id(EId);
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NodeId N2Id = G.getEdgeNode2Id(EId);
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NodeMetadata& N1Md = G.getNodeMetadata(N1Id);
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NodeMetadata& N2Md = G.getNodeMetadata(N2Id);
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const MatrixMetadata& MMd = NewCosts.getMetadata();
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N1Md.handleAddEdge(MMd, N1Id != G.getEdgeNode1Id(EId));
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N2Md.handleAddEdge(MMd, N2Id != G.getEdgeNode1Id(EId));
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}
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private:
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void removeFromCurrentSet(NodeId NId) {
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switch (G.getNodeMetadata(NId).getReductionState()) {
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case NodeMetadata::Unprocessed: break;
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case NodeMetadata::OptimallyReducible:
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assert(OptimallyReducibleNodes.find(NId) !=
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OptimallyReducibleNodes.end() &&
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"Node not in optimally reducible set.");
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OptimallyReducibleNodes.erase(NId);
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break;
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case NodeMetadata::ConservativelyAllocatable:
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assert(ConservativelyAllocatableNodes.find(NId) !=
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ConservativelyAllocatableNodes.end() &&
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"Node not in conservatively allocatable set.");
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ConservativelyAllocatableNodes.erase(NId);
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break;
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case NodeMetadata::NotProvablyAllocatable:
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assert(NotProvablyAllocatableNodes.find(NId) !=
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NotProvablyAllocatableNodes.end() &&
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"Node not in not-provably-allocatable set.");
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NotProvablyAllocatableNodes.erase(NId);
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break;
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}
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}
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void moveToOptimallyReducibleNodes(NodeId NId) {
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removeFromCurrentSet(NId);
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OptimallyReducibleNodes.insert(NId);
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G.getNodeMetadata(NId).setReductionState(
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NodeMetadata::OptimallyReducible);
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}
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void moveToConservativelyAllocatableNodes(NodeId NId) {
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removeFromCurrentSet(NId);
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ConservativelyAllocatableNodes.insert(NId);
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G.getNodeMetadata(NId).setReductionState(
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NodeMetadata::ConservativelyAllocatable);
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}
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void moveToNotProvablyAllocatableNodes(NodeId NId) {
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removeFromCurrentSet(NId);
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NotProvablyAllocatableNodes.insert(NId);
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G.getNodeMetadata(NId).setReductionState(
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NodeMetadata::NotProvablyAllocatable);
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}
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void setup() {
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// Set up worklists.
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for (auto NId : G.nodeIds()) {
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if (G.getNodeDegree(NId) < 3)
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moveToOptimallyReducibleNodes(NId);
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else if (G.getNodeMetadata(NId).isConservativelyAllocatable())
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moveToConservativelyAllocatableNodes(NId);
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else
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moveToNotProvablyAllocatableNodes(NId);
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}
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}
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// Compute a reduction order for the graph by iteratively applying PBQP
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// reduction rules. Locally optimal rules are applied whenever possible (R0,
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// R1, R2). If no locally-optimal rules apply then any conservatively
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// allocatable node is reduced. Finally, if no conservatively allocatable
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// node exists then the node with the lowest spill-cost:degree ratio is
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// selected.
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std::vector<GraphBase::NodeId> reduce() {
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assert(!G.empty() && "Cannot reduce empty graph.");
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typedef GraphBase::NodeId NodeId;
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std::vector<NodeId> NodeStack;
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// Consume worklists.
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while (true) {
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if (!OptimallyReducibleNodes.empty()) {
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NodeSet::iterator NItr = OptimallyReducibleNodes.begin();
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NodeId NId = *NItr;
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OptimallyReducibleNodes.erase(NItr);
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NodeStack.push_back(NId);
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switch (G.getNodeDegree(NId)) {
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case 0:
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break;
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case 1:
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applyR1(G, NId);
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break;
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case 2:
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applyR2(G, NId);
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break;
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default: llvm_unreachable("Not an optimally reducible node.");
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}
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} else if (!ConservativelyAllocatableNodes.empty()) {
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// Conservatively allocatable nodes will never spill. For now just
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// take the first node in the set and push it on the stack. When we
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// start optimizing more heavily for register preferencing, it may
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// would be better to push nodes with lower 'expected' or worst-case
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// register costs first (since early nodes are the most
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// constrained).
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NodeSet::iterator NItr = ConservativelyAllocatableNodes.begin();
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NodeId NId = *NItr;
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ConservativelyAllocatableNodes.erase(NItr);
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NodeStack.push_back(NId);
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G.disconnectAllNeighborsFromNode(NId);
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} else if (!NotProvablyAllocatableNodes.empty()) {
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NodeSet::iterator NItr =
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std::min_element(NotProvablyAllocatableNodes.begin(),
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NotProvablyAllocatableNodes.end(),
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SpillCostComparator(G));
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NodeId NId = *NItr;
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NotProvablyAllocatableNodes.erase(NItr);
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NodeStack.push_back(NId);
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G.disconnectAllNeighborsFromNode(NId);
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} else
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break;
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}
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return NodeStack;
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}
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class SpillCostComparator {
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|
public:
|
|
SpillCostComparator(const Graph& G) : G(G) {}
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bool operator()(NodeId N1Id, NodeId N2Id) {
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PBQPNum N1SC = G.getNodeCosts(N1Id)[0] / G.getNodeDegree(N1Id);
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|
PBQPNum N2SC = G.getNodeCosts(N2Id)[0] / G.getNodeDegree(N2Id);
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return N1SC < N2SC;
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|
}
|
|
private:
|
|
const Graph& G;
|
|
};
|
|
|
|
Graph& G;
|
|
typedef std::set<NodeId> NodeSet;
|
|
NodeSet OptimallyReducibleNodes;
|
|
NodeSet ConservativelyAllocatableNodes;
|
|
NodeSet NotProvablyAllocatableNodes;
|
|
};
|
|
|
|
class PBQPRAGraph : public PBQP::Graph<RegAllocSolverImpl> {
|
|
private:
|
|
typedef PBQP::Graph<RegAllocSolverImpl> BaseT;
|
|
public:
|
|
PBQPRAGraph(GraphMetadata Metadata) : BaseT(Metadata) {}
|
|
};
|
|
|
|
inline Solution solve(PBQPRAGraph& G) {
|
|
if (G.empty())
|
|
return Solution();
|
|
RegAllocSolverImpl RegAllocSolver(G);
|
|
return RegAllocSolver.solve();
|
|
}
|
|
|
|
} // namespace RegAlloc
|
|
} // namespace PBQP
|
|
|
|
/// @brief Create a PBQP register allocator instance.
|
|
FunctionPass *
|
|
createPBQPRegisterAllocator(char *customPassID = nullptr);
|
|
|
|
} // namespace llvm
|
|
|
|
#endif /* LLVM_CODEGEN_REGALLOCPBQP_H */
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