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 TargetMachineRegistry for the appropriate JIT to use, and
  11 // allows the user to specify a specific one on the commandline with -march=x.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "JIT.h"
  16 #include "llvm/Module.h"
  17 #include "llvm/ModuleProvider.h"
  18 #include "llvm/Support/RegistryParser.h"
  19 #include "llvm/Support/Streams.h"
  20 #include "llvm/Target/SubtargetFeature.h"
  21 #include "llvm/Target/TargetMachine.h"
  22 #include "llvm/Target/TargetMachineRegistry.h"
  23 using namespace llvm;
  24
  25 static cl::opt<const TargetMachineRegistry::entry*, false,
  26                RegistryParser<TargetMachine> >
  27 MArch("march", cl::desc("Architecture to generate assembly for:"));
  28
  29 static cl::opt<std::string>
  30 MCPU("mcpu",
  31   cl::desc("Target a specific cpu type (-mcpu=help for details)"),
  32   cl::value_desc("cpu-name"),
  33   cl::init(""));
  34
  35 static cl::list<std::string>
  36 MAttrs("mattr",
  37   cl::CommaSeparated,
  38   cl::desc("Target specific attributes (-mattr=help for details)"),
  39   cl::value_desc("a1,+a2,-a3,..."));
  40
  41 /// createInternal - Create an return a new JIT compiler if there is one
  42 /// available for the current target.  Otherwise, return null.
  43 ///
  44 ExecutionEngine *JIT::createJIT(ModuleProvider *MP, std::string *ErrorStr,
  45                                 JITMemoryManager *JMM,
  46                                 CodeGenOpt::Level OptLevel) {
  47   const TargetMachineRegistry::entry *TheArch = MArch;
  48   if (TheArch == 0) {
  49     std::string Error;
  50     TheArch = TargetMachineRegistry::getClosestTargetForJIT(Error);
  51     if (TheArch == 0) {
  52       if (ErrorStr)
  53         *ErrorStr = Error;
  54       return 0;
  55     }
  56   } else if (TheArch->JITMatchQualityFn() == 0) {
  57     cerr << "WARNING: This target JIT is not designed for the host you are"
  58          << " running.  If bad things happen, please choose a different "
  59          << "-march switch.\n";
  60   }
  61
  62   // Package up features to be passed to target/subtarget
  63   std::string FeaturesStr;
  64   if (!MCPU.empty() || !MAttrs.empty()) {
  65     SubtargetFeatures Features;
  66     Features.setCPU(MCPU);
  67     for (unsigned i = 0; i != MAttrs.size(); ++i)
  68       Features.AddFeature(MAttrs[i]);
  69     FeaturesStr = Features.getString();
  70   }
  71
  72   // Allocate a target...
  73   TargetMachine *Target = TheArch->CtorFn(*MP->getModule(), FeaturesStr);
  74   assert(Target && "Could not allocate target machine!");
  75
  76   // If the target supports JIT code generation, return a new JIT now.
  77   if (TargetJITInfo *TJ = Target->getJITInfo())
  78     return new JIT(MP, *Target, *TJ, JMM, OptLevel);
  79
  80   if (ErrorStr)
  81     *ErrorStr = "target does not support JIT code generation";
  82   return 0;
  83 }