1491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen//===-- RegisterClassInfo.cpp - Dynamic Register Class Info ---------------===// 2491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// 3491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// The LLVM Compiler Infrastructure 4491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// 5491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// This file is distributed under the University of Illinois Open Source 6491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// License. See LICENSE.TXT for details. 7491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// 8491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 9491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// 10491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// This file implements the RegisterClassInfo class which provides dynamic 1136b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines// information about target register classes. Callee-saved vs. caller-saved and 1236b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines// reserved registers depend on calling conventions and other dynamic 1336b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines// information, so some things cannot be determined statically. 14491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen// 15491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 16491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 171525260b3e50cc578939ef41b60609689eecfdd2Andrew Trick#include "llvm/CodeGen/RegisterClassInfo.h" 18fb9ebbf236974beac31705eaeb9f50ab585af6abJakob Stoklund Olesen#include "llvm/CodeGen/MachineFunction.h" 19fb9ebbf236974beac31705eaeb9f50ab585af6abJakob Stoklund Olesen#include "llvm/CodeGen/MachineRegisterInfo.h" 2027bc818eaf73efe169f95c4dd8f564fd051dd824Jakob Stoklund Olesen#include "llvm/Support/CommandLine.h" 21d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen#include "llvm/Support/Debug.h" 22d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen#include "llvm/Support/raw_ostream.h" 23d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Target/TargetMachine.h" 24d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen 25491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesenusing namespace llvm; 26491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 27dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines#define DEBUG_TYPE "regalloc" 28dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines 29f79b489571610cc5a97c050415b982e94a9989fdJakob Stoklund Olesenstatic cl::opt<unsigned> 30f79b489571610cc5a97c050415b982e94a9989fdJakob Stoklund OlesenStressRA("stress-regalloc", cl::Hidden, cl::init(0), cl::value_desc("N"), 31f79b489571610cc5a97c050415b982e94a9989fdJakob Stoklund Olesen cl::desc("Limit all regclasses to N registers")); 3227bc818eaf73efe169f95c4dd8f564fd051dd824Jakob Stoklund Olesen 33dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen HinesRegisterClassInfo::RegisterClassInfo() 34dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines : Tag(0), MF(nullptr), TRI(nullptr), CalleeSaved(nullptr) {} 35491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 36491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesenvoid RegisterClassInfo::runOnMachineFunction(const MachineFunction &mf) { 37491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen bool Update = false; 38491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen MF = &mf; 39491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 40491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // Allocate new array the first time we see a new target. 41491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen if (MF->getTarget().getRegisterInfo() != TRI) { 42491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen TRI = MF->getTarget().getRegisterInfo(); 43491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen RegClass.reset(new RCInfo[TRI->getNumRegClasses()]); 441f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick unsigned NumPSets = TRI->getNumRegPressureSets(); 451f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick PSetLimits.reset(new unsigned[NumPSets]); 461f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick std::fill(&PSetLimits[0], &PSetLimits[NumPSets], 0); 47491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen Update = true; 48491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen } 49491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 50491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // Does this MF have different CSRs? 5139b5c0c049a19c7a7feffc9506da07923cc136e4Jakob Stoklund Olesen const MCPhysReg *CSR = TRI->getCalleeSavedRegs(MF); 52ab5ceacbc11b68f1a4993aa38bad11bcfea42a4cJakob Stoklund Olesen if (Update || CSR != CalleeSaved) { 53491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // Build a CSRNum map. Every CSR alias gets an entry pointing to the last 54491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // overlapping CSR. 556edf90b8a7168e53409d161fb8b285094c4c9182Jakob Stoklund Olesen CSRNum.clear(); 566edf90b8a7168e53409d161fb8b285094c4c9182Jakob Stoklund Olesen CSRNum.resize(TRI->getNumRegs(), 0); 57491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen for (unsigned N = 0; unsigned Reg = CSR[N]; ++N) 58396618b43a85e12d290a90b181c6af5d7c0c5f11Jakob Stoklund Olesen for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) 59396618b43a85e12d290a90b181c6af5d7c0c5f11Jakob Stoklund Olesen CSRNum[*AI] = N + 1; // 0 means no CSR, 1 means CalleeSaved[0], ... 60491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen Update = true; 61491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen } 62491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen CalleeSaved = CSR; 63491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 64491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // Different reserved registers? 65fb9ebbf236974beac31705eaeb9f50ab585af6abJakob Stoklund Olesen const BitVector &RR = MF->getRegInfo().getReservedRegs(); 66fb9ebbf236974beac31705eaeb9f50ab585af6abJakob Stoklund Olesen if (Reserved.size() != RR.size() || RR != Reserved) { 67491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen Update = true; 68fb9ebbf236974beac31705eaeb9f50ab585af6abJakob Stoklund Olesen Reserved = RR; 69fb9ebbf236974beac31705eaeb9f50ab585af6abJakob Stoklund Olesen } 70491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 71491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // Invalidate cached information from previous function. 72491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen if (Update) 73491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen ++Tag; 74491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen} 75491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 76491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen/// compute - Compute the preferred allocation order for RC with reserved 77491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen/// registers filtered out. Volatile registers come first followed by CSR 78491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen/// aliases ordered according to the CSR order specified by the target. 79491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesenvoid RegisterClassInfo::compute(const TargetRegisterClass *RC) const { 80491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen RCInfo &RCI = RegClass[RC->getID()]; 81491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 82491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // Raw register count, including all reserved regs. 83491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen unsigned NumRegs = RC->getNumRegs(); 84491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 85491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen if (!RCI.Order) 8639b5c0c049a19c7a7feffc9506da07923cc136e4Jakob Stoklund Olesen RCI.Order.reset(new MCPhysReg[NumRegs]); 87491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 88491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen unsigned N = 0; 8939b5c0c049a19c7a7feffc9506da07923cc136e4Jakob Stoklund Olesen SmallVector<MCPhysReg, 16> CSRAlias; 90c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen unsigned MinCost = 0xff; 91c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen unsigned LastCost = ~0u; 92c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen unsigned LastCostChange = 0; 93491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 94491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // FIXME: Once targets reserve registers instead of removing them from the 95491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // allocation order, we can simply use begin/end here. 9639b5c0c049a19c7a7feffc9506da07923cc136e4Jakob Stoklund Olesen ArrayRef<MCPhysReg> RawOrder = RC->getRawAllocationOrder(*MF); 9779c890f64f3b67f9b11341aa452c4302b75184aaJakob Stoklund Olesen for (unsigned i = 0; i != RawOrder.size(); ++i) { 9879c890f64f3b67f9b11341aa452c4302b75184aaJakob Stoklund Olesen unsigned PhysReg = RawOrder[i]; 99491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // Remove reserved registers from the allocation order. 100491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen if (Reserved.test(PhysReg)) 101491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen continue; 102c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen unsigned Cost = TRI->getCostPerUse(PhysReg); 103c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen MinCost = std::min(MinCost, Cost); 104c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen 1057c48913af62ced0da03ba58755cf5f53ad587ba8Jakob Stoklund Olesen if (CSRNum[PhysReg]) 1067c48913af62ced0da03ba58755cf5f53ad587ba8Jakob Stoklund Olesen // PhysReg aliases a CSR, save it for later. 1077c48913af62ced0da03ba58755cf5f53ad587ba8Jakob Stoklund Olesen CSRAlias.push_back(PhysReg); 108c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen else { 109c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen if (Cost != LastCost) 110c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen LastCostChange = N; 111491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen RCI.Order[N++] = PhysReg; 112c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen LastCost = Cost; 113c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen } 114491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen } 115491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen RCI.NumRegs = N + CSRAlias.size(); 116491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen assert (RCI.NumRegs <= NumRegs && "Allocation order larger than regclass"); 117491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 1187c48913af62ced0da03ba58755cf5f53ad587ba8Jakob Stoklund Olesen // CSR aliases go after the volatile registers, preserve the target's order. 119c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen for (unsigned i = 0, e = CSRAlias.size(); i != e; ++i) { 120c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen unsigned PhysReg = CSRAlias[i]; 121c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen unsigned Cost = TRI->getCostPerUse(PhysReg); 122c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen if (Cost != LastCost) 123c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen LastCostChange = N; 124c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen RCI.Order[N++] = PhysReg; 125c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen LastCost = Cost; 126c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen } 127491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 12827bc818eaf73efe169f95c4dd8f564fd051dd824Jakob Stoklund Olesen // Register allocator stress test. Clip register class to N registers. 12927bc818eaf73efe169f95c4dd8f564fd051dd824Jakob Stoklund Olesen if (StressRA && RCI.NumRegs > StressRA) 13027bc818eaf73efe169f95c4dd8f564fd051dd824Jakob Stoklund Olesen RCI.NumRegs = StressRA; 13127bc818eaf73efe169f95c4dd8f564fd051dd824Jakob Stoklund Olesen 132f39031b360f135ece3bdc86151804dd1f3f51733Jakob Stoklund Olesen // Check if RC is a proper sub-class. 133f39031b360f135ece3bdc86151804dd1f3f51733Jakob Stoklund Olesen if (const TargetRegisterClass *Super = TRI->getLargestLegalSuperClass(RC)) 134f39031b360f135ece3bdc86151804dd1f3f51733Jakob Stoklund Olesen if (Super != RC && getNumAllocatableRegs(Super) > RCI.NumRegs) 135f39031b360f135ece3bdc86151804dd1f3f51733Jakob Stoklund Olesen RCI.ProperSubClass = true; 136f39031b360f135ece3bdc86151804dd1f3f51733Jakob Stoklund Olesen 137c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen RCI.MinCost = uint8_t(MinCost); 138c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen RCI.LastCostChange = LastCostChange; 139c7a275245f501e2f68a55af05c75bc9b6b50ec84Jakob Stoklund Olesen 140d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen DEBUG({ 141d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen dbgs() << "AllocationOrder(" << RC->getName() << ") = ["; 142687397c01387534e98d2e8332d4b91536290d778Jakob Stoklund Olesen for (unsigned I = 0; I != RCI.NumRegs; ++I) 143d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen dbgs() << ' ' << PrintReg(RCI.Order[I], TRI); 144f39031b360f135ece3bdc86151804dd1f3f51733Jakob Stoklund Olesen dbgs() << (RCI.ProperSubClass ? " ] (sub-class)\n" : " ]\n"); 145d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen }); 146d365fa9415ce31b5f0a6019b33c6f099a82f4e34Jakob Stoklund Olesen 147491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen // RCI is now up-to-date. 148491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen RCI.Tag = Tag; 149491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen} 150491a13691d3b30b8288dfc6e01ad6a58f69a4ce6Jakob Stoklund Olesen 1511f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick/// This is not accurate because two overlapping register sets may have some 1521f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick/// nonoverlapping reserved registers. However, computing the allocation order 1531f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick/// for all register classes would be too expensive. 1541f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trickunsigned RegisterClassInfo::computePSetLimit(unsigned Idx) const { 155dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines const TargetRegisterClass *RC = nullptr; 1561f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick unsigned NumRCUnits = 0; 1571f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick for (TargetRegisterInfo::regclass_iterator 1581f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick RI = TRI->regclass_begin(), RE = TRI->regclass_end(); RI != RE; ++RI) { 1591f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick const int *PSetID = TRI->getRegClassPressureSets(*RI); 1601f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick for (; *PSetID != -1; ++PSetID) { 1611f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick if ((unsigned)*PSetID == Idx) 1621f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick break; 1631f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick } 1641f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick if (*PSetID == -1) 1651f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick continue; 1661f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick 1671f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick // Found a register class that counts against this pressure set. 1681f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick // For efficiency, only compute the set order for the largest set. 1691f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick unsigned NUnits = TRI->getRegClassWeight(*RI).WeightLimit; 1701f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick if (!RC || NUnits > NumRCUnits) { 1711f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick RC = *RI; 1721f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick NumRCUnits = NUnits; 1731f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick } 1741f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick } 1751f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick compute(RC); 1761f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick unsigned NReserved = RC->getNumRegs() - getNumAllocatableRegs(RC); 1771f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick return TRI->getRegPressureSetLimit(Idx) 1781f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick - TRI->getRegClassWeight(RC).RegWeight * NReserved; 1791f8b48ab3262bd5623ecbda7b0c024884e8169d3Andrew Trick} 180