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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 =
     34         std::find_if(targets().begin(), targets().end(),
     35                      [&](const Target &T) { return ArchName == T.getName(); });
     36 
     37     if (I == targets().end()) {
     38       Error = "error: invalid target '" + ArchName + "'.\n";
     39       return nullptr;
     40     }
     41 
     42     TheTarget = &*I;
     43 
     44     // Adjust the triple to match (if known), otherwise stick with the
     45     // given triple.
     46     Triple::ArchType Type = Triple::getArchTypeForLLVMName(ArchName);
     47     if (Type != Triple::UnknownArch)
     48       TheTriple.setArch(Type);
     49   } else {
     50     // Get the target specific parser.
     51     std::string TempError;
     52     TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), TempError);
     53     if (!TheTarget) {
     54       Error = ": error: unable to get target for '"
     55             + TheTriple.getTriple()
     56             + "', see --version and --triple.\n";
     57       return nullptr;
     58     }
     59   }
     60 
     61   return TheTarget;
     62 }
     63 
     64 const Target *TargetRegistry::lookupTarget(const std::string &TT,
     65                                            std::string &Error) {
     66   // Provide special warning when no targets are initialized.
     67   if (targets().begin() == targets().end()) {
     68     Error = "Unable to find target for this triple (no targets are registered)";
     69     return nullptr;
     70   }
     71   Triple::ArchType Arch = Triple(TT).getArch();
     72   auto ArchMatch = [&](const Target &T) { return T.ArchMatchFn(Arch); };
     73   auto I = std::find_if(targets().begin(), targets().end(), ArchMatch);
     74 
     75   if (I == targets().end()) {
     76     Error = "No available targets are compatible with this triple, "
     77       "see -version for the available targets.";
     78     return nullptr;
     79   }
     80 
     81   auto J = std::find_if(std::next(I), targets().end(), ArchMatch);
     82   if (J != targets().end()) {
     83     Error = std::string("Cannot choose between targets \"") + I->Name +
     84             "\" and \"" + J->Name + "\"";
     85     return nullptr;
     86   }
     87 
     88   return &*I;
     89 }
     90 
     91 void TargetRegistry::RegisterTarget(Target &T,
     92                                     const char *Name,
     93                                     const char *ShortDesc,
     94                                     Target::ArchMatchFnTy ArchMatchFn,
     95                                     bool HasJIT) {
     96   assert(Name && ShortDesc && ArchMatchFn &&
     97          "Missing required target information!");
     98 
     99   // Check if this target has already been initialized, we allow this as a
    100   // convenience to some clients.
    101   if (T.Name)
    102     return;
    103 
    104   // Add to the list of targets.
    105   T.Next = FirstTarget;
    106   FirstTarget = &T;
    107 
    108   T.Name = Name;
    109   T.ShortDesc = ShortDesc;
    110   T.ArchMatchFn = ArchMatchFn;
    111   T.HasJIT = HasJIT;
    112 }
    113 
    114 static int TargetArraySortFn(const std::pair<StringRef, const Target *> *LHS,
    115                              const std::pair<StringRef, const Target *> *RHS) {
    116   return LHS->first.compare(RHS->first);
    117 }
    118 
    119 void TargetRegistry::printRegisteredTargetsForVersion() {
    120   std::vector<std::pair<StringRef, const Target*> > Targets;
    121   size_t Width = 0;
    122   for (const auto &T : TargetRegistry::targets()) {
    123     Targets.push_back(std::make_pair(T.getName(), &T));
    124     Width = std::max(Width, Targets.back().first.size());
    125   }
    126   array_pod_sort(Targets.begin(), Targets.end(), TargetArraySortFn);
    127 
    128   raw_ostream &OS = outs();
    129   OS << "  Registered Targets:\n";
    130   for (unsigned i = 0, e = Targets.size(); i != e; ++i) {
    131     OS << "    " << Targets[i].first;
    132     OS.indent(Width - Targets[i].first.size()) << " - "
    133       << Targets[i].second->getShortDescription() << '\n';
    134   }
    135   if (Targets.empty())
    136     OS << "    (none)\n";
    137 }
    138