1 //===-- MipsTargetMachine.cpp - Define TargetMachine for Mips -------------===// 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 // Implements the info about Mips target spec. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "MipsTargetMachine.h" 14 #include "MCTargetDesc/MipsABIInfo.h" 15 #include "MCTargetDesc/MipsMCTargetDesc.h" 16 #include "Mips.h" 17 #include "Mips16ISelDAGToDAG.h" 18 #include "MipsSEISelDAGToDAG.h" 19 #include "MipsSubtarget.h" 20 #include "MipsTargetObjectFile.h" 21 #include "llvm/ADT/Optional.h" 22 #include "llvm/ADT/STLExtras.h" 23 #include "llvm/ADT/StringRef.h" 24 #include "llvm/Analysis/TargetTransformInfo.h" 25 #include "llvm/CodeGen/GlobalISel/IRTranslator.h" 26 #include "llvm/CodeGen/GlobalISel/Legalizer.h" 27 #include "llvm/CodeGen/GlobalISel/RegBankSelect.h" 28 #include "llvm/CodeGen/GlobalISel/InstructionSelect.h" 29 #include "llvm/CodeGen/BasicTTIImpl.h" 30 #include "llvm/CodeGen/MachineFunction.h" 31 #include "llvm/CodeGen/Passes.h" 32 #include "llvm/CodeGen/TargetPassConfig.h" 33 #include "llvm/IR/Attributes.h" 34 #include "llvm/IR/Function.h" 35 #include "llvm/Support/CodeGen.h" 36 #include "llvm/Support/Debug.h" 37 #include "llvm/Support/TargetRegistry.h" 38 #include "llvm/Support/raw_ostream.h" 39 #include "llvm/Target/TargetOptions.h" 40 #include <string> 41 42 using namespace llvm; 43 44 #define DEBUG_TYPE "mips" 45 46 extern "C" void LLVMInitializeMipsTarget() { 47 // Register the target. 48 RegisterTargetMachine<MipsebTargetMachine> X(getTheMipsTarget()); 49 RegisterTargetMachine<MipselTargetMachine> Y(getTheMipselTarget()); 50 RegisterTargetMachine<MipsebTargetMachine> A(getTheMips64Target()); 51 RegisterTargetMachine<MipselTargetMachine> B(getTheMips64elTarget()); 52 53 PassRegistry *PR = PassRegistry::getPassRegistry(); 54 initializeGlobalISel(*PR); 55 initializeMipsDelaySlotFillerPass(*PR); 56 initializeMipsBranchExpansionPass(*PR); 57 initializeMicroMipsSizeReducePass(*PR); 58 initializeMipsPreLegalizerCombinerPass(*PR); 59 } 60 61 static std::string computeDataLayout(const Triple &TT, StringRef CPU, 62 const TargetOptions &Options, 63 bool isLittle) { 64 std::string Ret; 65 MipsABIInfo ABI = MipsABIInfo::computeTargetABI(TT, CPU, Options.MCOptions); 66 67 // There are both little and big endian mips. 68 if (isLittle) 69 Ret += "e"; 70 else 71 Ret += "E"; 72 73 if (ABI.IsO32()) 74 Ret += "-m:m"; 75 else 76 Ret += "-m:e"; 77 78 // Pointers are 32 bit on some ABIs. 79 if (!ABI.IsN64()) 80 Ret += "-p:32:32"; 81 82 // 8 and 16 bit integers only need to have natural alignment, but try to 83 // align them to 32 bits. 64 bit integers have natural alignment. 84 Ret += "-i8:8:32-i16:16:32-i64:64"; 85 86 // 32 bit registers are always available and the stack is at least 64 bit 87 // aligned. On N64 64 bit registers are also available and the stack is 88 // 128 bit aligned. 89 if (ABI.IsN64() || ABI.IsN32()) 90 Ret += "-n32:64-S128"; 91 else 92 Ret += "-n32-S64"; 93 94 return Ret; 95 } 96 97 static Reloc::Model getEffectiveRelocModel(bool JIT, 98 Optional<Reloc::Model> RM) { 99 if (!RM.hasValue() || JIT) 100 return Reloc::Static; 101 return *RM; 102 } 103 104 // On function prologue, the stack is created by decrementing 105 // its pointer. Once decremented, all references are done with positive 106 // offset from the stack/frame pointer, using StackGrowsUp enables 107 // an easier handling. 108 // Using CodeModel::Large enables different CALL behavior. 109 MipsTargetMachine::MipsTargetMachine(const Target &T, const Triple &TT, 110 StringRef CPU, StringRef FS, 111 const TargetOptions &Options, 112 Optional<Reloc::Model> RM, 113 Optional<CodeModel::Model> CM, 114 CodeGenOpt::Level OL, bool JIT, 115 bool isLittle) 116 : LLVMTargetMachine(T, computeDataLayout(TT, CPU, Options, isLittle), TT, 117 CPU, FS, Options, getEffectiveRelocModel(JIT, RM), 118 getEffectiveCodeModel(CM, CodeModel::Small), OL), 119 isLittle(isLittle), TLOF(llvm::make_unique<MipsTargetObjectFile>()), 120 ABI(MipsABIInfo::computeTargetABI(TT, CPU, Options.MCOptions)), 121 Subtarget(nullptr), DefaultSubtarget(TT, CPU, FS, isLittle, *this, 122 Options.StackAlignmentOverride), 123 NoMips16Subtarget(TT, CPU, FS.empty() ? "-mips16" : FS.str() + ",-mips16", 124 isLittle, *this, Options.StackAlignmentOverride), 125 Mips16Subtarget(TT, CPU, FS.empty() ? "+mips16" : FS.str() + ",+mips16", 126 isLittle, *this, Options.StackAlignmentOverride) { 127 Subtarget = &DefaultSubtarget; 128 initAsmInfo(); 129 } 130 131 MipsTargetMachine::~MipsTargetMachine() = default; 132 133 void MipsebTargetMachine::anchor() {} 134 135 MipsebTargetMachine::MipsebTargetMachine(const Target &T, const Triple &TT, 136 StringRef CPU, StringRef FS, 137 const TargetOptions &Options, 138 Optional<Reloc::Model> RM, 139 Optional<CodeModel::Model> CM, 140 CodeGenOpt::Level OL, bool JIT) 141 : MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, JIT, false) {} 142 143 void MipselTargetMachine::anchor() {} 144 145 MipselTargetMachine::MipselTargetMachine(const Target &T, const Triple &TT, 146 StringRef CPU, StringRef FS, 147 const TargetOptions &Options, 148 Optional<Reloc::Model> RM, 149 Optional<CodeModel::Model> CM, 150 CodeGenOpt::Level OL, bool JIT) 151 : MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, JIT, true) {} 152 153 const MipsSubtarget * 154 MipsTargetMachine::getSubtargetImpl(const Function &F) const { 155 Attribute CPUAttr = F.getFnAttribute("target-cpu"); 156 Attribute FSAttr = F.getFnAttribute("target-features"); 157 158 std::string CPU = !CPUAttr.hasAttribute(Attribute::None) 159 ? CPUAttr.getValueAsString().str() 160 : TargetCPU; 161 std::string FS = !FSAttr.hasAttribute(Attribute::None) 162 ? FSAttr.getValueAsString().str() 163 : TargetFS; 164 bool hasMips16Attr = 165 !F.getFnAttribute("mips16").hasAttribute(Attribute::None); 166 bool hasNoMips16Attr = 167 !F.getFnAttribute("nomips16").hasAttribute(Attribute::None); 168 169 bool HasMicroMipsAttr = 170 !F.getFnAttribute("micromips").hasAttribute(Attribute::None); 171 bool HasNoMicroMipsAttr = 172 !F.getFnAttribute("nomicromips").hasAttribute(Attribute::None); 173 174 // FIXME: This is related to the code below to reset the target options, 175 // we need to know whether or not the soft float flag is set on the 176 // function, so we can enable it as a subtarget feature. 177 bool softFloat = 178 F.hasFnAttribute("use-soft-float") && 179 F.getFnAttribute("use-soft-float").getValueAsString() == "true"; 180 181 if (hasMips16Attr) 182 FS += FS.empty() ? "+mips16" : ",+mips16"; 183 else if (hasNoMips16Attr) 184 FS += FS.empty() ? "-mips16" : ",-mips16"; 185 if (HasMicroMipsAttr) 186 FS += FS.empty() ? "+micromips" : ",+micromips"; 187 else if (HasNoMicroMipsAttr) 188 FS += FS.empty() ? "-micromips" : ",-micromips"; 189 if (softFloat) 190 FS += FS.empty() ? "+soft-float" : ",+soft-float"; 191 192 auto &I = SubtargetMap[CPU + FS]; 193 if (!I) { 194 // This needs to be done before we create a new subtarget since any 195 // creation will depend on the TM and the code generation flags on the 196 // function that reside in TargetOptions. 197 resetTargetOptions(F); 198 I = llvm::make_unique<MipsSubtarget>(TargetTriple, CPU, FS, isLittle, *this, 199 Options.StackAlignmentOverride); 200 } 201 return I.get(); 202 } 203 204 void MipsTargetMachine::resetSubtarget(MachineFunction *MF) { 205 LLVM_DEBUG(dbgs() << "resetSubtarget\n"); 206 207 Subtarget = const_cast<MipsSubtarget *>(getSubtargetImpl(MF->getFunction())); 208 MF->setSubtarget(Subtarget); 209 } 210 211 namespace { 212 213 /// Mips Code Generator Pass Configuration Options. 214 class MipsPassConfig : public TargetPassConfig { 215 public: 216 MipsPassConfig(MipsTargetMachine &TM, PassManagerBase &PM) 217 : TargetPassConfig(TM, PM) { 218 // The current implementation of long branch pass requires a scratch 219 // register ($at) to be available before branch instructions. Tail merging 220 // can break this requirement, so disable it when long branch pass is 221 // enabled. 222 EnableTailMerge = !getMipsSubtarget().enableLongBranchPass(); 223 } 224 225 MipsTargetMachine &getMipsTargetMachine() const { 226 return getTM<MipsTargetMachine>(); 227 } 228 229 const MipsSubtarget &getMipsSubtarget() const { 230 return *getMipsTargetMachine().getSubtargetImpl(); 231 } 232 233 void addIRPasses() override; 234 bool addInstSelector() override; 235 void addPreEmitPass() override; 236 void addPreRegAlloc() override; 237 bool addIRTranslator() override; 238 void addPreLegalizeMachineIR() override; 239 bool addLegalizeMachineIR() override; 240 bool addRegBankSelect() override; 241 bool addGlobalInstructionSelect() override; 242 }; 243 244 } // end anonymous namespace 245 246 TargetPassConfig *MipsTargetMachine::createPassConfig(PassManagerBase &PM) { 247 return new MipsPassConfig(*this, PM); 248 } 249 250 void MipsPassConfig::addIRPasses() { 251 TargetPassConfig::addIRPasses(); 252 addPass(createAtomicExpandPass()); 253 if (getMipsSubtarget().os16()) 254 addPass(createMipsOs16Pass()); 255 if (getMipsSubtarget().inMips16HardFloat()) 256 addPass(createMips16HardFloatPass()); 257 } 258 // Install an instruction selector pass using 259 // the ISelDag to gen Mips code. 260 bool MipsPassConfig::addInstSelector() { 261 addPass(createMipsModuleISelDagPass()); 262 addPass(createMips16ISelDag(getMipsTargetMachine(), getOptLevel())); 263 addPass(createMipsSEISelDag(getMipsTargetMachine(), getOptLevel())); 264 return false; 265 } 266 267 void MipsPassConfig::addPreRegAlloc() { 268 addPass(createMipsOptimizePICCallPass()); 269 } 270 271 TargetTransformInfo 272 MipsTargetMachine::getTargetTransformInfo(const Function &F) { 273 if (Subtarget->allowMixed16_32()) { 274 LLVM_DEBUG(errs() << "No Target Transform Info Pass Added\n"); 275 // FIXME: This is no longer necessary as the TTI returned is per-function. 276 return TargetTransformInfo(F.getParent()->getDataLayout()); 277 } 278 279 LLVM_DEBUG(errs() << "Target Transform Info Pass Added\n"); 280 return TargetTransformInfo(BasicTTIImpl(this, F)); 281 } 282 283 // Implemented by targets that want to run passes immediately before 284 // machine code is emitted. return true if -print-machineinstrs should 285 // print out the code after the passes. 286 void MipsPassConfig::addPreEmitPass() { 287 // Expand pseudo instructions that are sensitive to register allocation. 288 addPass(createMipsExpandPseudoPass()); 289 290 // The microMIPS size reduction pass performs instruction reselection for 291 // instructions which can be remapped to a 16 bit instruction. 292 addPass(createMicroMipsSizeReducePass()); 293 294 // The delay slot filler pass can potientially create forbidden slot hazards 295 // for MIPSR6 and therefore it should go before MipsBranchExpansion pass. 296 addPass(createMipsDelaySlotFillerPass()); 297 298 // This pass expands branches and takes care about the forbidden slot hazards. 299 // Expanding branches may potentially create forbidden slot hazards for 300 // MIPSR6, and fixing such hazard may potentially break a branch by extending 301 // its offset out of range. That's why this pass combine these two tasks, and 302 // runs them alternately until one of them finishes without any changes. Only 303 // then we can be sure that all branches are expanded properly and no hazards 304 // exists. 305 // Any new pass should go before this pass. 306 addPass(createMipsBranchExpansion()); 307 308 addPass(createMipsConstantIslandPass()); 309 } 310 311 bool MipsPassConfig::addIRTranslator() { 312 addPass(new IRTranslator()); 313 return false; 314 } 315 316 void MipsPassConfig::addPreLegalizeMachineIR() { 317 addPass(createMipsPreLegalizeCombiner()); 318 } 319 320 bool MipsPassConfig::addLegalizeMachineIR() { 321 addPass(new Legalizer()); 322 return false; 323 } 324 325 bool MipsPassConfig::addRegBankSelect() { 326 addPass(new RegBankSelect()); 327 return false; 328 } 329 330 bool MipsPassConfig::addGlobalInstructionSelect() { 331 addPass(new InstructionSelect()); 332 return false; 333 } 334