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