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/Module.h"
19#include "llvm/ADT/Triple.h"
20#include "llvm/MC/SubtargetFeature.h"
21#include "llvm/Target/TargetMachine.h"
22#include "llvm/Support/CommandLine.h"
23#include "llvm/Support/Host.h"
24#include "llvm/Support/TargetRegistry.h"
25
26using namespace llvm;
27
28TargetMachine *EngineBuilder::selectTarget() {
29  Triple TT(LLVM_HOSTTRIPLE);
30  return selectTarget(TT, MArch, MCPU, MAttrs);
31}
32
33/// selectTarget - Pick a target either via -march or by guessing the native
34/// arch.  Add any CPU features specified via -mcpu or -mattr.
35TargetMachine *EngineBuilder::selectTarget(const Triple &TargetTriple,
36                              StringRef MArch,
37                              StringRef MCPU,
38                              const SmallVectorImpl<std::string>& MAttrs) {
39  Triple TheTriple(TargetTriple);
40  if (TheTriple.getTriple().empty())
41    TheTriple.setTriple(sys::getDefaultTargetTriple());
42
43  // Adjust the triple to match what the user requested.
44  const Target *TheTarget = 0;
45  if (!MArch.empty()) {
46    for (TargetRegistry::iterator it = TargetRegistry::begin(),
47           ie = TargetRegistry::end(); it != ie; ++it) {
48      if (MArch == it->getName()) {
49        TheTarget = &*it;
50        break;
51      }
52    }
53
54    if (!TheTarget) {
55      if (ErrorStr)
56        *ErrorStr = "No available targets are compatible with this -march, "
57                    "see -version for the available targets.\n";
58      return 0;
59    }
60
61    // Adjust the triple to match (if known), otherwise stick with the
62    // requested/host triple.
63    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
64    if (Type != Triple::UnknownArch)
65      TheTriple.setArch(Type);
66  } else {
67    std::string Error;
68    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
69    if (TheTarget == 0) {
70      if (ErrorStr)
71        *ErrorStr = Error;
72      return 0;
73    }
74  }
75
76  // Package up features to be passed to target/subtarget
77  std::string FeaturesStr;
78  if (!MAttrs.empty()) {
79    SubtargetFeatures Features;
80    for (unsigned i = 0; i != MAttrs.size(); ++i)
81      Features.AddFeature(MAttrs[i]);
82    FeaturesStr = Features.getString();
83  }
84
85  // Allocate a target...
86  TargetMachine *Target = TheTarget->createTargetMachine(TheTriple.getTriple(),
87                                                         MCPU, FeaturesStr,
88                                                         Options,
89                                                         RelocModel, CMModel,
90                                                         OptLevel);
91  assert(Target && "Could not allocate target machine!");
92  return Target;
93}
94