lib/ExecutionEngine/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 "llvm/ExecutionEngine/ExecutionEngine.h"
  17 #include "llvm/Module.h"
  18 #include "llvm/ADT/Triple.h"
  19 #include "llvm/MC/SubtargetFeature.h"
  20 #include "llvm/Support/CommandLine.h"
  21 #include "llvm/Support/raw_ostream.h"
  22 #include "llvm/Support/Host.h"
  23 #include "llvm/Target/TargetMachine.h"
  24 #include "llvm/Target/TargetRegistry.h"
  25 using namespace llvm;
  26
  27 /// selectTarget - Pick a target either via -march or by guessing the native
  28 /// arch.  Add any CPU features specified via -mcpu or -mattr.
  29 TargetMachine *EngineBuilder::selectTarget(Module *Mod,
  30                               StringRef MArch,
  31                               StringRef MCPU,
  32                               const SmallVectorImpl<std::string>& MAttrs,
  33                               std::string *ErrorStr) {
  34   Triple TheTriple(Mod->getTargetTriple());
  35   if (TheTriple.getTriple().empty())
  36     TheTriple.setTriple(sys::getHostTriple());
  37
  38   // Adjust the triple to match what the user requested.
  39   const Target *TheTarget = 0;
  40   if (!MArch.empty()) {
  41     for (TargetRegistry::iterator it = TargetRegistry::begin(),
  42            ie = TargetRegistry::end(); it != ie; ++it) {
  43       if (MArch == it->getName()) {
  44         TheTarget = &*it;
  45         break;
  46       }
  47     }
  48
  49     if (!TheTarget) {
  50       *ErrorStr = "No available targets are compatible with this -march, "
  51         "see -version for the available targets.\n";
  52       return 0;
  53     }
  54
  55     // Adjust the triple to match (if known), otherwise stick with the
  56     // module/host triple.
  57     Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
  58     if (Type != Triple::UnknownArch)
  59       TheTriple.setArch(Type);
  60   } else {
  61     std::string Error;
  62     TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
  63     if (TheTarget == 0) {
  64       if (ErrorStr)
  65         *ErrorStr = Error;
  66       return 0;
  67     }
  68   }
  69
  70   if (!TheTarget->hasJIT()) {
  71     errs() << "WARNING: This target JIT is not designed for the host you are"
  72            << " running.  If bad things happen, please choose a different "
  73            << "-march switch.\n";
  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 =
  87     TheTarget->createTargetMachine(TheTriple.getTriple(), MCPU, FeaturesStr);
  88   assert(Target && "Could not allocate target machine!");
  89   return Target;
  90 }