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