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      1 //===--- TargetRegistry.cpp - Target registration -------------------------===//
      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 #include "llvm/Support/TargetRegistry.h"
     11 #include "llvm/ADT/STLExtras.h"
     12 #include "llvm/ADT/StringRef.h"
     13 #include "llvm/Support/Host.h"
     14 #include "llvm/Support/raw_ostream.h"
     15 #include <cassert>
     16 #include <vector>
     17 using namespace llvm;
     18 
     19 // Clients are responsible for avoid race conditions in registration.
     20 static Target *FirstTarget = nullptr;
     21 
     22 TargetRegistry::iterator TargetRegistry::begin() {
     23   return iterator(FirstTarget);
     24 }
     25 
     26 const Target *TargetRegistry::lookupTarget(const std::string &ArchName,
     27                                            Triple &TheTriple,
     28                                            std::string &Error) {
     29   // Allocate target machine.  First, check whether the user has explicitly
     30   // specified an architecture to compile for. If so we have to look it up by
     31   // name, because it might be a backend that has no mapping to a target triple.
     32   const Target *TheTarget = nullptr;
     33   if (!ArchName.empty()) {
     34     for (TargetRegistry::iterator it = TargetRegistry::begin(),
     35            ie = TargetRegistry::end(); it != ie; ++it) {
     36       if (ArchName == it->getName()) {
     37         TheTarget = &*it;
     38         break;
     39       }
     40     }
     41 
     42     if (!TheTarget) {
     43       Error = "error: invalid target '" + ArchName + "'.\n";
     44       return nullptr;
     45     }
     46 
     47     // Adjust the triple to match (if known), otherwise stick with the
     48     // given triple.
     49     Triple::ArchType Type = Triple::getArchTypeForLLVMName(ArchName);
     50     if (Type != Triple::UnknownArch)
     51       TheTriple.setArch(Type);
     52   } else {
     53     // Get the target specific parser.
     54     std::string TempError;
     55     TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), TempError);
     56     if (!TheTarget) {
     57       Error = ": error: unable to get target for '"
     58             + TheTriple.getTriple()
     59             + "', see --version and --triple.\n";
     60       return nullptr;
     61     }
     62   }
     63 
     64   return TheTarget;
     65 }
     66 
     67 const Target *TargetRegistry::lookupTarget(const std::string &TT,
     68                                            std::string &Error) {
     69   // Provide special warning when no targets are initialized.
     70   if (begin() == end()) {
     71     Error = "Unable to find target for this triple (no targets are registered)";
     72     return nullptr;
     73   }
     74   const Target *Matching = nullptr;
     75   Triple::ArchType Arch =  Triple(TT).getArch();
     76   for (iterator it = begin(), ie = end(); it != ie; ++it) {
     77     if (it->ArchMatchFn(Arch)) {
     78       if (Matching) {
     79         Error = std::string("Cannot choose between targets \"") +
     80           Matching->Name  + "\" and \"" + it->Name + "\"";
     81         return nullptr;
     82       }
     83       Matching = &*it;
     84     }
     85   }
     86 
     87   if (!Matching) {
     88     Error = "No available targets are compatible with this triple, "
     89       "see -version for the available targets.";
     90     return nullptr;
     91   }
     92 
     93   return Matching;
     94 }
     95 
     96 void TargetRegistry::RegisterTarget(Target &T,
     97                                     const char *Name,
     98                                     const char *ShortDesc,
     99                                     Target::ArchMatchFnTy ArchMatchFn,
    100                                     bool HasJIT) {
    101   assert(Name && ShortDesc && ArchMatchFn &&
    102          "Missing required target information!");
    103 
    104   // Check if this target has already been initialized, we allow this as a
    105   // convenience to some clients.
    106   if (T.Name)
    107     return;
    108 
    109   // Add to the list of targets.
    110   T.Next = FirstTarget;
    111   FirstTarget = &T;
    112 
    113   T.Name = Name;
    114   T.ShortDesc = ShortDesc;
    115   T.ArchMatchFn = ArchMatchFn;
    116   T.HasJIT = HasJIT;
    117 }
    118 
    119 static int TargetArraySortFn(const std::pair<StringRef, const Target *> *LHS,
    120                              const std::pair<StringRef, const Target *> *RHS) {
    121   return LHS->first.compare(RHS->first);
    122 }
    123 
    124 void TargetRegistry::printRegisteredTargetsForVersion() {
    125   std::vector<std::pair<StringRef, const Target*> > Targets;
    126   size_t Width = 0;
    127   for (TargetRegistry::iterator I = TargetRegistry::begin(),
    128        E = TargetRegistry::end();
    129        I != E; ++I) {
    130     Targets.push_back(std::make_pair(I->getName(), &*I));
    131     Width = std::max(Width, Targets.back().first.size());
    132   }
    133   array_pod_sort(Targets.begin(), Targets.end(), TargetArraySortFn);
    134 
    135   raw_ostream &OS = outs();
    136   OS << "  Registered Targets:\n";
    137   for (unsigned i = 0, e = Targets.size(); i != e; ++i) {
    138     OS << "    " << Targets[i].first;
    139     OS.indent(Width - Targets[i].first.size()) << " - "
    140       << Targets[i].second->getShortDescription() << '\n';
    141   }
    142   if (Targets.empty())
    143     OS << "    (none)\n";
    144 }
    145