1 //===-- TargetSelect.cpp - Target Chooser Code ----------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This just asks the TargetRegistry for the appropriate target to use, and 11 // allows the user to specify a specific one on the commandline with -march=x, 12 // -mcpu=y, and -mattr=a,-b,+c. Clients should initialize targets prior to 13 // calling selectTarget(). 14 // 15 //===----------------------------------------------------------------------===// 16 17 #include "llvm/ADT/Triple.h" 18 #include "llvm/ExecutionEngine/ExecutionEngine.h" 19 #include "llvm/IR/Module.h" 20 #include "llvm/MC/SubtargetFeature.h" 21 #include "llvm/Support/Host.h" 22 #include "llvm/Support/TargetRegistry.h" 23 #include "llvm/Target/TargetMachine.h" 24 25 using namespace llvm; 26 27 TargetMachine *EngineBuilder::selectTarget() { 28 Triple TT; 29 30 // MCJIT can generate code for remote targets, but the old JIT and Interpreter 31 // must use the host architecture. 32 if (WhichEngine != EngineKind::Interpreter && M) 33 TT.setTriple(M->getTargetTriple()); 34 35 return selectTarget(TT, MArch, MCPU, MAttrs); 36 } 37 38 /// selectTarget - Pick a target either via -march or by guessing the native 39 /// arch. Add any CPU features specified via -mcpu or -mattr. 40 TargetMachine *EngineBuilder::selectTarget(const Triple &TargetTriple, 41 StringRef MArch, 42 StringRef MCPU, 43 const SmallVectorImpl<std::string>& MAttrs) { 44 Triple TheTriple(TargetTriple); 45 if (TheTriple.getTriple().empty()) 46 TheTriple.setTriple(sys::getProcessTriple()); 47 48 // Adjust the triple to match what the user requested. 49 const Target *TheTarget = nullptr; 50 if (!MArch.empty()) { 51 auto I = find_if(TargetRegistry::targets(), 52 [&](const Target &T) { return MArch == T.getName(); }); 53 54 if (I == TargetRegistry::targets().end()) { 55 if (ErrorStr) 56 *ErrorStr = "No available targets are compatible with this -march, " 57 "see -version for the available targets.\n"; 58 return nullptr; 59 } 60 61 TheTarget = &*I; 62 63 // Adjust the triple to match (if known), otherwise stick with the 64 // requested/host triple. 65 Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch); 66 if (Type != Triple::UnknownArch) 67 TheTriple.setArch(Type); 68 } else { 69 std::string Error; 70 TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error); 71 if (!TheTarget) { 72 if (ErrorStr) 73 *ErrorStr = Error; 74 return nullptr; 75 } 76 } 77 78 // Package up features to be passed to target/subtarget 79 std::string FeaturesStr; 80 if (!MAttrs.empty()) { 81 SubtargetFeatures Features; 82 for (unsigned i = 0; i != MAttrs.size(); ++i) 83 Features.AddFeature(MAttrs[i]); 84 FeaturesStr = Features.getString(); 85 } 86 87 // FIXME: non-iOS ARM FastISel is broken with MCJIT. 88 if (TheTriple.getArch() == Triple::arm && 89 !TheTriple.isiOS() && 90 OptLevel == CodeGenOpt::None) { 91 OptLevel = CodeGenOpt::Less; 92 } 93 94 // Allocate a target... 95 TargetMachine *Target = 96 TheTarget->createTargetMachine(TheTriple.getTriple(), MCPU, FeaturesStr, 97 Options, RelocModel, CMModel, OptLevel, 98 /*JIT*/ true); 99 Target->Options.EmulatedTLS = EmulatedTLS; 100 Target->Options.ExplicitEmulatedTLS = true; 101 102 assert(Target && "Could not allocate target machine!"); 103 return Target; 104 } 105
