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", cl::desc("Architecture to generate assembly for (see --version)"));
  30
  31 static cl::opt<std::string>
  32 MCPU("mcpu",
  33   cl::desc("Target a specific cpu type (-mcpu=help for details)"),
  34   cl::value_desc("cpu-name"),
  35   cl::init(""));
  36
  37 static cl::list<std::string>
  38 MAttrs("mattr",
  39   cl::CommaSeparated,
  40   cl::desc("Target specific attributes (-mattr=help for details)"),
  41   cl::value_desc("a1,+a2,-a3,..."));
  42
  43 /// selectTarget - Pick a target either via -march or by guessing the native
  44 /// arch.  Add any CPU features specified via -mcpu or -mattr.
  45 TargetMachine *JIT::selectTarget(ModuleProvider *MP, std::string *ErrorStr) {
  46   Triple TheTriple(sys::getHostTriple());
  47
  48   // Adjust the triple to match what the user requested.
  49   if (!MArch.empty())
  50     TheTriple.setArch(Triple::getArchTypeForLLVMName(MArch));
  51
  52   std::string Error;
  53   const Target *TheTarget =
  54     TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
  55   if (TheTarget == 0) {
  56     if (ErrorStr)
  57       *ErrorStr = Error;
  58     return 0;
  59   }
  60
  61   if (!TheTarget->hasJIT()) {
  62     errs() << "WARNING: This target JIT is not designed for the host you are"
  63            << " running.  If bad things happen, please choose a different "
  64            << "-march switch.\n";
  65   }
  66
  67   // Package up features to be passed to target/subtarget
  68   std::string FeaturesStr;
  69   if (!MCPU.empty() || !MAttrs.empty()) {
  70     SubtargetFeatures Features;
  71     Features.setCPU(MCPU);
  72     for (unsigned i = 0; i != MAttrs.size(); ++i)
  73       Features.AddFeature(MAttrs[i]);
  74     FeaturesStr = Features.getString();
  75   }
  76
  77   // Allocate a target...
  78   TargetMachine *Target =
  79     TheTarget->createTargetMachine(TheTriple.getTriple(), FeaturesStr);
  80   assert(Target && "Could not allocate target machine!");
  81   return Target;
  82 }