1 //===-- PowerPCSubtarget.cpp - PPC Subtarget Information ------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the PPC specific subclass of TargetSubtargetInfo. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "PPCSubtarget.h" 14 #include "GISel/PPCCallLowering.h" 15 #include "GISel/PPCLegalizerInfo.h" 16 #include "GISel/PPCRegisterBankInfo.h" 17 #include "PPC.h" 18 #include "PPCRegisterInfo.h" 19 #include "PPCSelectionDAGInfo.h" 20 #include "PPCTargetMachine.h" 21 #include "llvm/CodeGen/GlobalISel/InstructionSelect.h" 22 #include "llvm/CodeGen/GlobalISel/InstructionSelector.h" 23 #include "llvm/CodeGen/MachineFunction.h" 24 #include "llvm/CodeGen/MachineScheduler.h" 25 #include "llvm/IR/GlobalAlias.h" 26 #include "llvm/IR/GlobalValue.h" 27 #include "llvm/IR/GlobalVariable.h" 28 #include "llvm/MC/TargetRegistry.h" 29 #include "llvm/Support/CommandLine.h" 30 #include "llvm/Target/TargetMachine.h" 31 #include "llvm/TargetParser/PPCTargetParser.h" 32 #include <cstdlib> 33 34 using namespace llvm; 35 36 #define DEBUG_TYPE "ppc-subtarget" 37 38 #define GET_SUBTARGETINFO_TARGET_DESC 39 #define GET_SUBTARGETINFO_CTOR 40 #include "PPCGenSubtargetInfo.inc" 41 42 static cl::opt<bool> 43 EnableMachinePipeliner("ppc-enable-pipeliner", 44 cl::desc("Enable Machine Pipeliner for PPC"), 45 cl::init(false), cl::Hidden); 46 47 PPCSubtarget &PPCSubtarget::initializeSubtargetDependencies(StringRef CPU, 48 StringRef TuneCPU, 49 StringRef FS) { 50 initializeEnvironment(); 51 initSubtargetFeatures(CPU, TuneCPU, FS); 52 return *this; 53 } 54 55 PPCSubtarget::PPCSubtarget(const Triple &TT, const std::string &CPU, 56 const std::string &TuneCPU, const std::string &FS, 57 const PPCTargetMachine &TM) 58 : PPCGenSubtargetInfo(TT, CPU, TuneCPU, FS), TargetTriple(TT), 59 IsPPC64(TargetTriple.getArch() == Triple::ppc64 || 60 TargetTriple.getArch() == Triple::ppc64le), 61 TM(TM), FrameLowering(initializeSubtargetDependencies(CPU, TuneCPU, FS)), 62 InstrInfo(*this), TLInfo(TM, *this) { 63 TSInfo = std::make_unique<PPCSelectionDAGInfo>(); 64 65 CallLoweringInfo.reset(new PPCCallLowering(*getTargetLowering())); 66 Legalizer.reset(new PPCLegalizerInfo(*this)); 67 auto *RBI = new PPCRegisterBankInfo(*getRegisterInfo()); 68 RegBankInfo.reset(RBI); 69 70 InstSelector.reset(createPPCInstructionSelector(TM, *this, *RBI)); 71 } 72 73 PPCSubtarget::~PPCSubtarget() = default; 74 75 const SelectionDAGTargetInfo *PPCSubtarget::getSelectionDAGInfo() const { 76 return TSInfo.get(); 77 } 78 79 void PPCSubtarget::initializeEnvironment() { 80 StackAlignment = Align(16); 81 CPUDirective = PPC::DIR_NONE; 82 HasPOPCNTD = POPCNTD_Unavailable; 83 } 84 85 void PPCSubtarget::initSubtargetFeatures(StringRef CPU, StringRef TuneCPU, 86 StringRef FS) { 87 // Determine default and user specified characteristics 88 std::string CPUName = std::string(CPU); 89 if (CPUName.empty() || CPU == "generic") { 90 if (TargetTriple.getSubArch() == Triple::PPCSubArch_spe) 91 CPUName = "e500"; 92 else 93 CPUName = std::string(PPC::getNormalizedPPCTargetCPU(TargetTriple)); 94 } 95 96 // Determine the CPU to schedule for. 97 if (TuneCPU.empty()) TuneCPU = CPUName; 98 99 // Initialize scheduling itinerary for the specified CPU. 100 InstrItins = getInstrItineraryForCPU(CPUName); 101 102 // Parse features string. 103 ParseSubtargetFeatures(CPUName, TuneCPU, FS); 104 105 // If the user requested use of 64-bit regs, but the cpu selected doesn't 106 // support it, ignore. 107 if (IsPPC64 && has64BitSupport()) 108 Use64BitRegs = true; 109 110 if (TargetTriple.isPPC32SecurePlt()) 111 IsSecurePlt = true; 112 113 if (HasSPE && IsPPC64) 114 report_fatal_error( "SPE is only supported for 32-bit targets.\n", false); 115 if (HasSPE && (HasAltivec || HasVSX || HasFPU)) 116 report_fatal_error( 117 "SPE and traditional floating point cannot both be enabled.\n", false); 118 119 // If not SPE, set standard FPU 120 if (!HasSPE) 121 HasFPU = true; 122 123 StackAlignment = getPlatformStackAlignment(); 124 125 // Determine endianness. 126 IsLittleEndian = TM.isLittleEndian(); 127 128 if (HasAIXSmallLocalExecTLS || HasAIXSmallLocalDynamicTLS) { 129 if (!TargetTriple.isOSAIX() || !IsPPC64) 130 report_fatal_error("The aix-small-local-[exec|dynamic]-tls attribute is " 131 "only supported on AIX in " 132 "64-bit mode.\n", 133 false); 134 // The aix-small-local-[exec|dynamic]-tls attribute should only be used with 135 // -data-sections, as having data sections turned off with this option 136 // is not ideal for performance. Moreover, the 137 // small-local-[exec|dynamic]-tls region is a limited resource, and should 138 // not be used for variables that may be replaced. 139 if (!TM.getDataSections()) 140 report_fatal_error("The aix-small-local-[exec|dynamic]-tls attribute can " 141 "only be specified with " 142 "-data-sections.\n", 143 false); 144 } 145 146 if (HasAIXShLibTLSModelOpt && (!TargetTriple.isOSAIX() || !IsPPC64)) 147 report_fatal_error("The aix-shared-lib-tls-model-opt attribute " 148 "is only supported on AIX in 64-bit mode.\n", 149 false); 150 } 151 152 bool PPCSubtarget::enableMachineScheduler() const { return true; } 153 154 bool PPCSubtarget::enableMachinePipeliner() const { 155 return getSchedModel().hasInstrSchedModel() && EnableMachinePipeliner; 156 } 157 158 bool PPCSubtarget::useDFAforSMS() const { return false; } 159 160 // This overrides the PostRAScheduler bit in the SchedModel for each CPU. 161 bool PPCSubtarget::enablePostRAScheduler() const { return true; } 162 163 PPCGenSubtargetInfo::AntiDepBreakMode PPCSubtarget::getAntiDepBreakMode() const { 164 return TargetSubtargetInfo::ANTIDEP_ALL; 165 } 166 167 void PPCSubtarget::getCriticalPathRCs(RegClassVector &CriticalPathRCs) const { 168 CriticalPathRCs.clear(); 169 CriticalPathRCs.push_back(isPPC64() ? 170 &PPC::G8RCRegClass : &PPC::GPRCRegClass); 171 } 172 173 void PPCSubtarget::overrideSchedPolicy(MachineSchedPolicy &Policy, 174 unsigned NumRegionInstrs) const { 175 // The GenericScheduler that we use defaults to scheduling bottom up only. 176 // We want to schedule from both the top and the bottom and so we set 177 // OnlyBottomUp to false. 178 // We want to do bi-directional scheduling since it provides a more balanced 179 // schedule leading to better performance. 180 Policy.OnlyBottomUp = false; 181 // Spilling is generally expensive on all PPC cores, so always enable 182 // register-pressure tracking. 183 Policy.ShouldTrackPressure = true; 184 } 185 186 bool PPCSubtarget::useAA() const { 187 return true; 188 } 189 190 bool PPCSubtarget::enableSubRegLiveness() const { return true; } 191 192 bool PPCSubtarget::isGVIndirectSymbol(const GlobalValue *GV) const { 193 if (isAIXABI()) { 194 if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) 195 // On AIX the only symbols that aren't indirect are toc-data. 196 return !GVar->hasAttribute("toc-data"); 197 198 return true; 199 } 200 201 // Large code model always uses the TOC even for local symbols. 202 if (TM.getCodeModel() == CodeModel::Large) 203 return true; 204 205 if (TM.shouldAssumeDSOLocal(GV)) 206 return false; 207 return true; 208 } 209 210 CodeModel::Model PPCSubtarget::getCodeModel(const TargetMachine &TM, 211 const GlobalValue *GV) const { 212 // If there isn't an attribute to override the module code model 213 // this will be the effective code model. 214 CodeModel::Model ModuleModel = TM.getCodeModel(); 215 216 // Initially support per global code model for AIX only. 217 if (!isAIXABI()) 218 return ModuleModel; 219 220 // Only GlobalVariables carry an attribute which can override the module code 221 // model. 222 assert(GV && "Unexpected NULL GlobalValue"); 223 const GlobalVariable *GlobalVar = 224 [](const GlobalValue *GV) -> const GlobalVariable * { 225 const GlobalVariable *Var = dyn_cast<GlobalVariable>(GV); 226 if (Var) 227 return Var; 228 229 const GlobalAlias *Alias = dyn_cast<GlobalAlias>(GV); 230 if (Alias) 231 return dyn_cast<GlobalVariable>(Alias->getAliaseeObject()); 232 233 return nullptr; 234 }(GV); 235 236 if (!GlobalVar) 237 return ModuleModel; 238 239 std::optional<CodeModel::Model> MaybeCodeModel = GlobalVar->getCodeModel(); 240 if (MaybeCodeModel) { 241 CodeModel::Model CM = *MaybeCodeModel; 242 assert((CM == CodeModel::Small || CM == CodeModel::Large) && 243 "invalid code model for AIX"); 244 return CM; 245 } 246 247 return ModuleModel; 248 } 249 250 bool PPCSubtarget::isELFv2ABI() const { return TM.isELFv2ABI(); } 251 bool PPCSubtarget::isPPC64() const { return TM.isPPC64(); } 252 253 bool PPCSubtarget::isUsingPCRelativeCalls() const { 254 return isPPC64() && hasPCRelativeMemops() && isELFv2ABI() && 255 CodeModel::Medium == getTargetMachine().getCodeModel(); 256 } 257 258 // GlobalISEL 259 const CallLowering *PPCSubtarget::getCallLowering() const { 260 return CallLoweringInfo.get(); 261 } 262 263 const RegisterBankInfo *PPCSubtarget::getRegBankInfo() const { 264 return RegBankInfo.get(); 265 } 266 267 const LegalizerInfo *PPCSubtarget::getLegalizerInfo() const { 268 return Legalizer.get(); 269 } 270 271 InstructionSelector *PPCSubtarget::getInstructionSelector() const { 272 return InstSelector.get(); 273 } 274