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