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
selectTarget()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.
selectTarget(const Triple & TargetTriple,StringRef MArch,StringRef MCPU,const SmallVectorImpl<std::string> & MAttrs)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 = std::find_if(
52 TargetRegistry::targets().begin(), TargetRegistry::targets().end(),
53 [&](const Target &T) { return MArch == T.getName(); });
54
55 if (I == TargetRegistry::targets().end()) {
56 if (ErrorStr)
57 *ErrorStr = "No available targets are compatible with this -march, "
58 "see -version for the available targets.\n";
59 return nullptr;
60 }
61
62 TheTarget = &*I;
63
64 // Adjust the triple to match (if known), otherwise stick with the
65 // requested/host triple.
66 Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
67 if (Type != Triple::UnknownArch)
68 TheTriple.setArch(Type);
69 } else {
70 std::string Error;
71 TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
72 if (!TheTarget) {
73 if (ErrorStr)
74 *ErrorStr = Error;
75 return nullptr;
76 }
77 }
78
79 // Package up features to be passed to target/subtarget
80 std::string FeaturesStr;
81 if (!MAttrs.empty()) {
82 SubtargetFeatures Features;
83 for (unsigned i = 0; i != MAttrs.size(); ++i)
84 Features.AddFeature(MAttrs[i]);
85 FeaturesStr = Features.getString();
86 }
87
88 // FIXME: non-iOS ARM FastISel is broken with MCJIT.
89 if (TheTriple.getArch() == Triple::arm &&
90 !TheTriple.isiOS() &&
91 OptLevel == CodeGenOpt::None) {
92 OptLevel = CodeGenOpt::Less;
93 }
94
95 // Allocate a target...
96 TargetMachine *Target = TheTarget->createTargetMachine(TheTriple.getTriple(),
97 MCPU, FeaturesStr,
98 Options,
99 RelocModel, CMModel,
100 OptLevel);
101 assert(Target && "Could not allocate target machine!");
102 return Target;
103 }
104