1ccc9581e8b79b4216cb1143344bdae9342722d5dJakob Stoklund Olesen//===-- RegAllocBasic.cpp - Basic Register Allocator ----------------------===// 214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// 314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// The LLVM Compiler Infrastructure 414e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// 514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// This file is distributed under the University of Illinois Open Source 614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// License. See LICENSE.TXT for details. 714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// 814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick//===----------------------------------------------------------------------===// 914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// 1014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// This file defines the RABasic function pass, which provides a minimal 1114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// implementation of the basic register allocator. 1214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// 1314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick//===----------------------------------------------------------------------===// 1414e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 1514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#define DEBUG_TYPE "regalloc" 16d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/CodeGen/Passes.h" 17812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen#include "AllocationOrder.h" 18cfafc54040cc9722995558124f253d05a038176bJakob Stoklund Olesen#include "LiveDebugVariables.h" 19d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "RegAllocBase.h" 2014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "Spiller.h" 218a83d54528c197675ba0f21ebe95ac30fa3d8841Andrew Trick#include "llvm/Analysis/AliasAnalysis.h" 2214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/CodeGen/CalcSpillWeights.h" 23e141a4960f702bef957b28abde3801ec64e32d87Andrew Trick#include "llvm/CodeGen/LiveIntervalAnalysis.h" 24789d5d85ba6e9259a8e0f0bcfbd06a59ad164512Pete Cooper#include "llvm/CodeGen/LiveRangeEdit.h" 251ead68d769f27f6d68d4aaeffe4199fa2cacbc95Jakob Stoklund Olesen#include "llvm/CodeGen/LiveRegMatrix.h" 2614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/CodeGen/LiveStackAnalysis.h" 274eed756153b84c211114a3e9186bf0cb55d4b394Benjamin Kramer#include "llvm/CodeGen/MachineBlockFrequencyInfo.h" 2814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/CodeGen/MachineFunctionPass.h" 2914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/CodeGen/MachineInstr.h" 3014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/CodeGen/MachineLoopInfo.h" 3114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/CodeGen/MachineRegisterInfo.h" 3214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/CodeGen/RegAllocRegistry.h" 331ead68d769f27f6d68d4aaeffe4199fa2cacbc95Jakob Stoklund Olesen#include "llvm/CodeGen/VirtRegMap.h" 34d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/PassAnalysisSupport.h" 35d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Support/Debug.h" 36d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Support/raw_ostream.h" 3714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick#include "llvm/Target/TargetMachine.h" 38e141a4960f702bef957b28abde3801ec64e32d87Andrew Trick#include "llvm/Target/TargetRegisterInfo.h" 39953af2c3c560a13bd5eeb676c128b7e362dca684Jakob Stoklund Olesen#include <cstdlib> 4098d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen#include <queue> 41e16eecc323879744dcff4f359ba9ccdb25bd6909Andrew Trick 4214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trickusing namespace llvm; 4314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 4414e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trickstatic RegisterRegAlloc basicRegAlloc("basic", "basic register allocator", 4514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick createBasicRegisterAllocator); 4614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 47c62feda741f9d5811b625967c40f1847fb2040e7Benjamin Kramernamespace { 4898d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen struct CompSpillWeight { 4998d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen bool operator()(LiveInterval *A, LiveInterval *B) const { 5098d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen return A->weight < B->weight; 5198d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen } 5298d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen }; 5398d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen} 5498d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen 5598d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesennamespace { 5614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick/// RABasic provides a minimal implementation of the basic register allocation 5714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick/// algorithm. It prioritizes live virtual registers by spill weight and spills 5814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick/// whenever a register is unavailable. This is not practical in production but 5914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick/// provides a useful baseline both for measuring other allocators and comparing 6014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick/// the speed of the basic algorithm against other styles of allocators. 6114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trickclass RABasic : public MachineFunctionPass, public RegAllocBase 6214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick{ 6314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick // context 6418c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick MachineFunction *MF; 6514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 6614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick // state 67200241e4de11981523b3d14f3acab6129efed701Andy Gibbs OwningPtr<Spiller> SpillerInstance; 6898d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen std::priority_queue<LiveInterval*, std::vector<LiveInterval*>, 6998d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen CompSpillWeight> Queue; 70a94e635cec8dff2c9b39343643fe204dfab390dcJakob Stoklund Olesen 71a94e635cec8dff2c9b39343643fe204dfab390dcJakob Stoklund Olesen // Scratch space. Allocated here to avoid repeated malloc calls in 72a94e635cec8dff2c9b39343643fe204dfab390dcJakob Stoklund Olesen // selectOrSplit(). 73a94e635cec8dff2c9b39343643fe204dfab390dcJakob Stoklund Olesen BitVector UsableRegs; 74a94e635cec8dff2c9b39343643fe204dfab390dcJakob Stoklund Olesen 7514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trickpublic: 7614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick RABasic(); 7714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 7814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick /// Return the pass name. 7914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick virtual const char* getPassName() const { 8014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick return "Basic Register Allocator"; 8114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick } 8214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 8314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick /// RABasic analysis usage. 8418c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick virtual void getAnalysisUsage(AnalysisUsage &AU) const; 8514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 8614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick virtual void releaseMemory(); 8714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 8818c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick virtual Spiller &spiller() { return *SpillerInstance; } 89f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick 90d0bec3e62c98b1f0ef3a41db8f95599b2014c131Jakob Stoklund Olesen virtual float getPriority(LiveInterval *LI) { return LI->weight; } 91d0bec3e62c98b1f0ef3a41db8f95599b2014c131Jakob Stoklund Olesen 9298d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen virtual void enqueue(LiveInterval *LI) { 9398d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen Queue.push(LI); 9498d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen } 9598d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen 9698d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen virtual LiveInterval *dequeue() { 9798d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen if (Queue.empty()) 9898d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen return 0; 9998d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen LiveInterval *LI = Queue.top(); 10098d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen Queue.pop(); 10198d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen return LI; 10298d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen } 10398d9648de7d571b2e6d139b65961a70d1833b0d7Jakob Stoklund Olesen 10418c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick virtual unsigned selectOrSplit(LiveInterval &VirtReg, 10518c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick SmallVectorImpl<LiveInterval*> &SplitVRegs); 10614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 10714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick /// Perform register allocation. 10814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick virtual bool runOnMachineFunction(MachineFunction &mf); 10914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 110a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen // Helper for spilling all live virtual registers currently unified under preg 111a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen // that interfere with the most recently queried lvr. Return true if spilling 112a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen // was successful, and append any new spilled/split intervals to splitLVRs. 113a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen bool spillInterferences(LiveInterval &VirtReg, unsigned PhysReg, 114a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen SmallVectorImpl<LiveInterval*> &SplitVRegs); 115a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen 11614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick static char ID; 11714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick}; 11814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 11914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trickchar RABasic::ID = 0; 12014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 12114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick} // end anonymous namespace 12214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 12314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew TrickRABasic::RABasic(): MachineFunctionPass(ID) { 124cfafc54040cc9722995558124f253d05a038176bJakob Stoklund Olesen initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry()); 12514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick initializeLiveIntervalsPass(*PassRegistry::getPassRegistry()); 12614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick initializeSlotIndexesPass(*PassRegistry::getPassRegistry()); 1275b220213bfe9c37c2bb41a7ae0804e06a14f1007Rafael Espindola initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry()); 12842b7a71dc7381d1f38bf7b7201fc26dd80453364Andrew Trick initializeMachineSchedulerPass(*PassRegistry::getPassRegistry()); 12914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry()); 13014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick initializeLiveStacksPass(*PassRegistry::getPassRegistry()); 131964bc25e5a03be208427ce2ebadb22a42681ef9cJakob Stoklund Olesen initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry()); 13214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry()); 13314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick initializeVirtRegMapPass(*PassRegistry::getPassRegistry()); 134812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen initializeLiveRegMatrixPass(*PassRegistry::getPassRegistry()); 13514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick} 13614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 13718c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trickvoid RABasic::getAnalysisUsage(AnalysisUsage &AU) const { 13818c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.setPreservesCFG(); 13918c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addRequired<AliasAnalysis>(); 14018c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addPreserved<AliasAnalysis>(); 14118c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addRequired<LiveIntervals>(); 14205ec712e7f75635abbdd84dced69f4a45fe0f541Jakob Stoklund Olesen AU.addPreserved<LiveIntervals>(); 14318c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addPreserved<SlotIndexes>(); 144cfafc54040cc9722995558124f253d05a038176bJakob Stoklund Olesen AU.addRequired<LiveDebugVariables>(); 145cfafc54040cc9722995558124f253d05a038176bJakob Stoklund Olesen AU.addPreserved<LiveDebugVariables>(); 14618c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addRequired<CalculateSpillWeights>(); 14718c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addRequired<LiveStacks>(); 14818c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addPreserved<LiveStacks>(); 1494eed756153b84c211114a3e9186bf0cb55d4b394Benjamin Kramer AU.addRequired<MachineBlockFrequencyInfo>(); 1504eed756153b84c211114a3e9186bf0cb55d4b394Benjamin Kramer AU.addPreserved<MachineBlockFrequencyInfo>(); 15118c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addRequiredID(MachineDominatorsID); 15218c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addPreservedID(MachineDominatorsID); 15318c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addRequired<MachineLoopInfo>(); 15418c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addPreserved<MachineLoopInfo>(); 15518c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addRequired<VirtRegMap>(); 15618c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick AU.addPreserved<VirtRegMap>(); 157812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen AU.addRequired<LiveRegMatrix>(); 158812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen AU.addPreserved<LiveRegMatrix>(); 15918c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick MachineFunctionPass::getAnalysisUsage(AU); 16014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick} 16114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 16214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trickvoid RABasic::releaseMemory() { 16318c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick SpillerInstance.reset(0); 16414e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick} 16514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 166a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen 167a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen// Spill or split all live virtual registers currently unified under PhysReg 168a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen// that interfere with VirtReg. The newly spilled or split live intervals are 169a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen// returned by appending them to SplitVRegs. 170a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesenbool RABasic::spillInterferences(LiveInterval &VirtReg, unsigned PhysReg, 171a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen SmallVectorImpl<LiveInterval*> &SplitVRegs) { 172a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen // Record each interference and determine if all are spillable before mutating 173a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen // either the union or live intervals. 174812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen SmallVector<LiveInterval*, 8> Intfs; 175812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen 176a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen // Collect interferences assigned to any alias of the physical register. 177812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) { 178812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen LiveIntervalUnion::Query &Q = Matrix->query(VirtReg, *Units); 179812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen Q.collectInterferingVRegs(); 180812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen if (Q.seenUnspillableVReg()) 181a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen return false; 182812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen for (unsigned i = Q.interferingVRegs().size(); i; --i) { 183812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen LiveInterval *Intf = Q.interferingVRegs()[i - 1]; 184812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen if (!Intf->isSpillable() || Intf->weight > VirtReg.weight) 185812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen return false; 186812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen Intfs.push_back(Intf); 187a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen } 188a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen } 189a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen DEBUG(dbgs() << "spilling " << TRI->getName(PhysReg) << 190a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen " interferences with " << VirtReg << "\n"); 191812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen assert(!Intfs.empty() && "expected interference"); 192a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen 193a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen // Spill each interfering vreg allocated to PhysReg or an alias. 194812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen for (unsigned i = 0, e = Intfs.size(); i != e; ++i) { 195812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen LiveInterval &Spill = *Intfs[i]; 196812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen 197812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // Skip duplicates. 198812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen if (!VRM->hasPhys(Spill.reg)) 199812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen continue; 200812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen 201812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // Deallocate the interfering vreg by removing it from the union. 202812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // A LiveInterval instance may not be in a union during modification! 203812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen Matrix->unassign(Spill); 204812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen 205812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // Spill the extracted interval. 206812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen LiveRangeEdit LRE(&Spill, SplitVRegs, *MF, *LIS, VRM); 207812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen spiller().spill(LRE); 208812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen } 209a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen return true; 210a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen} 211a8bd9a68f7c00fe1d895bb5e27ff804aa33abd64Jakob Stoklund Olesen 21214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// Driver for the register assignment and splitting heuristics. 21314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// Manages iteration over the LiveIntervalUnions. 21413bdbb0544900643b4520f67cc48c6046c515c65Andrew Trick// 21518c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick// This is a minimal implementation of register assignment and splitting that 21618c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick// spills whenever we run out of registers. 21714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// 21814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// selectOrSplit can only be called once per live virtual register. We then do a 21914e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// single interference test for each register the correct class until we find an 22014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// available register. So, the number of interference tests in the worst case is 22114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick// |vregs| * |machineregs|. And since the number of interference tests is 22218c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick// minimal, there is no value in caching them outside the scope of 22318c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick// selectOrSplit(). 22418c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trickunsigned RABasic::selectOrSplit(LiveInterval &VirtReg, 22518c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick SmallVectorImpl<LiveInterval*> &SplitVRegs) { 226f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick // Populate a list of physical register spill candidates. 22718c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick SmallVector<unsigned, 8> PhysRegSpillCands; 228e141a4960f702bef957b28abde3801ec64e32d87Andrew Trick 22913bdbb0544900643b4520f67cc48c6046c515c65Andrew Trick // Check for an available register in this class. 230812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen AllocationOrder Order(VirtReg.reg, *VRM, RegClassInfo); 231812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen while (unsigned PhysReg = Order.next()) { 232812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // Check for interference in PhysReg 233812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen switch (Matrix->checkInterference(VirtReg, PhysReg)) { 234812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen case LiveRegMatrix::IK_Free: 235812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // PhysReg is available, allocate it. 23618c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick return PhysReg; 237f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick 238812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen case LiveRegMatrix::IK_VirtReg: 239812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // Only virtual registers in the way, we may be able to spill them. 24018c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick PhysRegSpillCands.push_back(PhysReg); 241812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen continue; 242812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen 243812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen default: 244812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen // RegMask or RegUnit interference. 245812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen continue; 246e141a4960f702bef957b28abde3801ec64e32d87Andrew Trick } 24714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick } 248812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen 249f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick // Try to spill another interfering reg with less spill weight. 25018c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick for (SmallVectorImpl<unsigned>::iterator PhysRegI = PhysRegSpillCands.begin(), 251812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen PhysRegE = PhysRegSpillCands.end(); PhysRegI != PhysRegE; ++PhysRegI) { 252812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen if (!spillInterferences(VirtReg, *PhysRegI, SplitVRegs)) 253812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen continue; 25413bdbb0544900643b4520f67cc48c6046c515c65Andrew Trick 255812cda9a5cc26b1f8dda6f909bf5062c215b65d7Jakob Stoklund Olesen assert(!Matrix->checkInterference(VirtReg, *PhysRegI) && 2562b38c51f0ece16ef00068da56bee4623fb9ae485Jakob Stoklund Olesen "Interference after spill."); 257f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick // Tell the caller to allocate to this newly freed physical register. 25818c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick return *PhysRegI; 259e141a4960f702bef957b28abde3801ec64e32d87Andrew Trick } 260bf4e10f2f69db24c107cb61d6fe10ed5b2047374Jakob Stoklund Olesen 26118c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick // No other spill candidates were found, so spill the current VirtReg. 26218c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick DEBUG(dbgs() << "spilling: " << VirtReg << '\n'); 263bf4e10f2f69db24c107cb61d6fe10ed5b2047374Jakob Stoklund Olesen if (!VirtReg.isSpillable()) 264bf4e10f2f69db24c107cb61d6fe10ed5b2047374Jakob Stoklund Olesen return ~0u; 26520942dcd8634ad75091fe89669868cfebf74e869Jakob Stoklund Olesen LiveRangeEdit LRE(&VirtReg, SplitVRegs, *MF, *LIS, VRM); 26647dbf6cef761c25cfeb0aa7d624a6f98288bb96aJakob Stoklund Olesen spiller().spill(LRE); 26713bdbb0544900643b4520f67cc48c6046c515c65Andrew Trick 268f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick // The live virtual register requesting allocation was spilled, so tell 269f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick // the caller not to allocate anything during this round. 270f4baeaf8485f01beda46d29fd55753199dc68070Andrew Trick return 0; 271e141a4960f702bef957b28abde3801ec64e32d87Andrew Trick} 27214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 27314e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trickbool RABasic::runOnMachineFunction(MachineFunction &mf) { 27414e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick DEBUG(dbgs() << "********** BASIC REGISTER ALLOCATION **********\n" 27514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick << "********** Function: " 276986d76d7b3844b9a2f3d01a48975952749267a93David Blaikie << mf.getName() << '\n'); 27714e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 27818c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick MF = &mf; 279d4348a2dc24c4fb012c1b9b20e71908f52049283Jakob Stoklund Olesen RegAllocBase::init(getAnalysis<VirtRegMap>(), 280d4348a2dc24c4fb012c1b9b20e71908f52049283Jakob Stoklund Olesen getAnalysis<LiveIntervals>(), 281d4348a2dc24c4fb012c1b9b20e71908f52049283Jakob Stoklund Olesen getAnalysis<LiveRegMatrix>()); 282842759662ba3eae35d6078643983a07266be9aa5Jakob Stoklund Olesen SpillerInstance.reset(createInlineSpiller(*this, *MF, *VRM)); 28313bdbb0544900643b4520f67cc48c6046c515c65Andrew Trick 284e16eecc323879744dcff4f359ba9ccdb25bd6909Andrew Trick allocatePhysRegs(); 28514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 28614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick // Diagnostic output before rewriting 28718c57a8a09a7c79fbcf4348b0ad8135246ab984fAndrew Trick DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *VRM << "\n"); 28814e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 289e16eecc323879744dcff4f359ba9ccdb25bd6909Andrew Trick releaseMemory(); 29014e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick return true; 29114e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick} 29214e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick 29313bdbb0544900643b4520f67cc48c6046c515c65Andrew TrickFunctionPass* llvm::createBasicRegisterAllocator() 29414e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick{ 29514e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick return new RABasic(); 29614e8d71cc945034d4ee6e76be00e00f14efac62fAndrew Trick} 297