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 (UseMCJIT && 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 for (TargetRegistry::iterator it = TargetRegistry::begin(),
53 ie = TargetRegistry::end(); it != ie; ++it) {
54 if (MArch == it->getName()) {
55 TheTarget = &*it;
56 break;
57 }
58 }
59
60 if (!TheTarget) {
61 if (ErrorStr)
62 *ErrorStr = "No available targets are compatible with this -march, "
63 "see -version for the available targets.\n";
64 return nullptr;
65 }
66
67 // Adjust the triple to match (if known), otherwise stick with the
68 // requested/host triple.
69 Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
70 if (Type != Triple::UnknownArch)
71 TheTriple.setArch(Type);
72 } else {
73 std::string Error;
74 TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
75 if (!TheTarget) {
76 if (ErrorStr)
77 *ErrorStr = Error;
78 return nullptr;
79 }
80 }
81
82 // Package up features to be passed to target/subtarget
83 std::string FeaturesStr;
84 if (!MAttrs.empty()) {
85 SubtargetFeatures Features;
86 for (unsigned i = 0; i != MAttrs.size(); ++i)
87 Features.AddFeature(MAttrs[i]);
88 FeaturesStr = Features.getString();
89 }
90
91 // FIXME: non-iOS ARM FastISel is broken with MCJIT.
92 if (UseMCJIT &&
93 TheTriple.getArch() == Triple::arm &&
94 !TheTriple.isiOS() &&
95 OptLevel == CodeGenOpt::None) {
96 OptLevel = CodeGenOpt::Less;
97 }
98
99 // Allocate a target...
100 TargetMachine *Target = TheTarget->createTargetMachine(TheTriple.getTriple(),
101 MCPU, FeaturesStr,
102 Options,
103 RelocModel, CMModel,
104 OptLevel);
105 assert(Target && "Could not allocate target machine!");
106 return Target;
107 }
108