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/ExecutionEngine/ExecutionEngine.h"
17#include "llvm/IR/Module.h"
18#include "llvm/MC/TargetRegistry.h"
19#include "llvm/Target/TargetMachine.h"
20#include "llvm/TargetParser/Host.h"
21#include "llvm/TargetParser/SubtargetFeature.h"
22#include "llvm/TargetParser/Triple.h"
23
24using namespace llvm;
25
26TargetMachine *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 = M->getTargetTriple();
33
34 return selectTarget(TargetTriple: 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.
39TargetMachine *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(Range: TargetRegistry::targets(),
51 P: [&](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(Str: MArch);
65 if (Type != Triple::UnknownArch)
66 TheTriple.setArch(Kind: Type);
67 } else {
68 std::string Error;
69 TheTarget = TargetRegistry::lookupTarget(TheTriple, 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(String: MAttrs[i]);
83 FeaturesStr = Features.getString();
84 }
85
86 // Allocate a target...
87 TargetMachine *Target = TheTarget->createTargetMachine(
88 TT: TheTriple, CPU: MCPU, Features: FeaturesStr, Options, RM: RelocModel, CM: CMModel, OL: OptLevel,
89 /*JIT=*/true);
90 Target->Options.EmulatedTLS = EmulatedTLS;
91
92 assert(Target && "Could not allocate target machine!");
93 return Target;
94}
95