lib/ExecutionEngine/JIT/TargetSelect.cpp

   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 JIT to use, and allows
  11 // the user to specify a specific one on the commandline with -march=x. Clients
  12 // should initialize targets prior to calling createJIT.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "JIT.h"
  17 #include "llvm/Module.h"
  18 #include "llvm/ModuleProvider.h"
  19 #include "llvm/ADT/Triple.h"
  20 #include "llvm/Support/CommandLine.h"
  21 #include "llvm/Support/raw_ostream.h"
  22 #include "llvm/System/Host.h"
  23 #include "llvm/Target/SubtargetFeature.h"
  24 #include "llvm/Target/TargetMachine.h"
  25 #include "llvm/Target/TargetRegistry.h"
  26 using namespace llvm;
  27
  28 static cl::opt<std::string>
  29 MArch("march",
  30       cl::desc("Architecture to generate assembly for (see --version)"));
  31
  32 static cl::opt<std::string>
  33 MCPU("mcpu",
  34   cl::desc("Target a specific cpu type (-mcpu=help for details)"),
  35   cl::value_desc("cpu-name"),
  36   cl::init(""));
  37
  38 static cl::list<std::string>
  39 MAttrs("mattr",
  40   cl::CommaSeparated,
  41   cl::desc("Target specific attributes (-mattr=help for details)"),
  42   cl::value_desc("a1,+a2,-a3,..."));
  43
  44 /// selectTarget - Pick a target either via -march or by guessing the native
  45 /// arch.  Add any CPU features specified via -mcpu or -mattr.
  46 TargetMachine *JIT::selectTarget(ModuleProvider *MP, std::string *ErrorStr) {
  47   Module &Mod = *MP->getModule();
  48
  49   Triple TheTriple(Mod.getTargetTriple());
  50   if (TheTriple.getTriple().empty())
  51     TheTriple.setTriple(sys::getHostTriple());
  52
  53   // Adjust the triple to match what the user requested.
  54   const Target *TheTarget = 0;
  55   if (!MArch.empty()) {
  56     for (TargetRegistry::iterator it = TargetRegistry::begin(),
  57            ie = TargetRegistry::end(); it != ie; ++it) {
  58       if (MArch == it->getName()) {
  59         TheTarget = &*it;
  60         break;
  61       }
  62     }
  63
  64     if (!TheTarget) {
  65       *ErrorStr = "No available targets are compatible with this -march, "
  66         "see -version for the available targets.\n";
  67       return 0;
  68     }
  69
  70     // Adjust the triple to match (if known), otherwise stick with the
  71     // module/host triple.
  72     Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
  73     if (Type != Triple::UnknownArch)
  74       TheTriple.setArch(Type);
  75   } else {
  76     std::string Error;
  77     TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
  78     if (TheTarget == 0) {
  79       if (ErrorStr)
  80         *ErrorStr = Error;
  81       return 0;
  82     }
  83   }
  84
  85   if (!TheTarget->hasJIT()) {
  86     errs() << "WARNING: This target JIT is not designed for the host you are"
  87            << " running.  If bad things happen, please choose a different "
  88            << "-march switch.\n";
  89   }
  90
  91   // Package up features to be passed to target/subtarget
  92   std::string FeaturesStr;
  93   if (!MCPU.empty() || !MAttrs.empty()) {
  94     SubtargetFeatures Features;
  95     Features.setCPU(MCPU);
  96     for (unsigned i = 0; i != MAttrs.size(); ++i)
  97       Features.AddFeature(MAttrs[i]);
  98     FeaturesStr = Features.getString();
  99   }
 100
 101   // Allocate a target...
 102   TargetMachine *Target =
 103     TheTarget->createTargetMachine(TheTriple.getTriple(), FeaturesStr);
 104   assert(Target && "Could not allocate target machine!");
 105   return Target;
 106 }