forked from OSchip/llvm-project
157 lines
5.3 KiB
C++
157 lines
5.3 KiB
C++
//===-- LiveRegMatrix.cpp - Track register interference -------------------===//
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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 LiveRegMatrix analysis pass.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "regalloc"
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#include "llvm/CodeGen/LiveRegMatrix.h"
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#include "RegisterCoalescer.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/VirtRegMap.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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using namespace llvm;
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STATISTIC(NumAssigned , "Number of registers assigned");
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STATISTIC(NumUnassigned , "Number of registers unassigned");
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char LiveRegMatrix::ID = 0;
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INITIALIZE_PASS_BEGIN(LiveRegMatrix, "liveregmatrix",
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"Live Register Matrix", false, false)
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INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
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INITIALIZE_PASS_DEPENDENCY(VirtRegMap)
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INITIALIZE_PASS_END(LiveRegMatrix, "liveregmatrix",
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"Live Register Matrix", false, false)
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LiveRegMatrix::LiveRegMatrix() : MachineFunctionPass(ID),
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UserTag(0), RegMaskTag(0), RegMaskVirtReg(0) {}
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void LiveRegMatrix::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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AU.addRequiredTransitive<LiveIntervals>();
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AU.addRequiredTransitive<VirtRegMap>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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bool LiveRegMatrix::runOnMachineFunction(MachineFunction &MF) {
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TRI = MF.getTarget().getRegisterInfo();
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MRI = &MF.getRegInfo();
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LIS = &getAnalysis<LiveIntervals>();
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VRM = &getAnalysis<VirtRegMap>();
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unsigned NumRegUnits = TRI->getNumRegUnits();
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if (NumRegUnits != Matrix.size())
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Queries.reset(new LiveIntervalUnion::Query[NumRegUnits]);
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Matrix.init(LIUAlloc, NumRegUnits);
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// Make sure no stale queries get reused.
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invalidateVirtRegs();
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return false;
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}
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void LiveRegMatrix::releaseMemory() {
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for (unsigned i = 0, e = Matrix.size(); i != e; ++i) {
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Matrix[i].clear();
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Queries[i].clear();
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}
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}
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void LiveRegMatrix::assign(LiveInterval &VirtReg, unsigned PhysReg) {
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DEBUG(dbgs() << "assigning " << PrintReg(VirtReg.reg, TRI)
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<< " to " << PrintReg(PhysReg, TRI) << ':');
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assert(!VRM->hasPhys(VirtReg.reg) && "Duplicate VirtReg assignment");
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VRM->assignVirt2Phys(VirtReg.reg, PhysReg);
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MRI->setPhysRegUsed(PhysReg);
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for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
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DEBUG(dbgs() << ' ' << PrintRegUnit(*Units, TRI));
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Matrix[*Units].unify(VirtReg);
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}
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++NumAssigned;
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DEBUG(dbgs() << '\n');
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}
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void LiveRegMatrix::unassign(LiveInterval &VirtReg) {
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unsigned PhysReg = VRM->getPhys(VirtReg.reg);
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DEBUG(dbgs() << "unassigning " << PrintReg(VirtReg.reg, TRI)
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<< " from " << PrintReg(PhysReg, TRI) << ':');
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VRM->clearVirt(VirtReg.reg);
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for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
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DEBUG(dbgs() << ' ' << PrintRegUnit(*Units, TRI));
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Matrix[*Units].extract(VirtReg);
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}
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++NumUnassigned;
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DEBUG(dbgs() << '\n');
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}
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bool LiveRegMatrix::checkRegMaskInterference(LiveInterval &VirtReg,
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unsigned PhysReg) {
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// Check if the cached information is valid.
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// The same BitVector can be reused for all PhysRegs.
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// We could cache multiple VirtRegs if it becomes necessary.
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if (RegMaskVirtReg != VirtReg.reg || RegMaskTag != UserTag) {
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RegMaskVirtReg = VirtReg.reg;
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RegMaskTag = UserTag;
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RegMaskUsable.clear();
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LIS->checkRegMaskInterference(VirtReg, RegMaskUsable);
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}
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// The BitVector is indexed by PhysReg, not register unit.
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// Regmask interference is more fine grained than regunits.
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// For example, a Win64 call can clobber %ymm8 yet preserve %xmm8.
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return !RegMaskUsable.empty() && (!PhysReg || !RegMaskUsable.test(PhysReg));
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}
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bool LiveRegMatrix::checkRegUnitInterference(LiveInterval &VirtReg,
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unsigned PhysReg) {
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if (VirtReg.empty())
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return false;
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CoalescerPair CP(VirtReg.reg, PhysReg, *TRI);
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for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
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const LiveRange &UnitRange = LIS->getRegUnit(*Units);
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if (VirtReg.overlaps(UnitRange, CP, *LIS->getSlotIndexes()))
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return true;
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}
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return false;
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}
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LiveIntervalUnion::Query &LiveRegMatrix::query(LiveInterval &VirtReg,
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unsigned RegUnit) {
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LiveIntervalUnion::Query &Q = Queries[RegUnit];
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Q.init(UserTag, &VirtReg, &Matrix[RegUnit]);
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return Q;
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}
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LiveRegMatrix::InterferenceKind
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LiveRegMatrix::checkInterference(LiveInterval &VirtReg, unsigned PhysReg) {
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if (VirtReg.empty())
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return IK_Free;
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// Regmask interference is the fastest check.
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if (checkRegMaskInterference(VirtReg, PhysReg))
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return IK_RegMask;
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// Check for fixed interference.
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if (checkRegUnitInterference(VirtReg, PhysReg))
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return IK_RegUnit;
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// Check the matrix for virtual register interference.
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for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units)
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if (query(VirtReg, *Units).checkInterference())
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return IK_VirtReg;
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return IK_Free;
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}
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