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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 = 0;
21 
begin()22 TargetRegistry::iterator TargetRegistry::begin() {
23   return iterator(FirstTarget);
24 }
25 
lookupTarget(const std::string & TT,std::string & Error)26 const Target *TargetRegistry::lookupTarget(const std::string &TT,
27                                            std::string &Error) {
28   // Provide special warning when no targets are initialized.
29   if (begin() == end()) {
30     Error = "Unable to find target for this triple (no targets are registered)";
31     return 0;
32   }
33   const Target *Best = 0, *EquallyBest = 0;
34   unsigned BestQuality = 0;
35   for (iterator it = begin(), ie = end(); it != ie; ++it) {
36     if (unsigned Qual = it->TripleMatchQualityFn(TT)) {
37       if (!Best || Qual > BestQuality) {
38         Best = &*it;
39         EquallyBest = 0;
40         BestQuality = Qual;
41       } else if (Qual == BestQuality)
42         EquallyBest = &*it;
43     }
44   }
45 
46   if (!Best) {
47     Error = "No available targets are compatible with this triple, "
48       "see -version for the available targets.";
49     return 0;
50   }
51 
52   // Otherwise, take the best target, but make sure we don't have two equally
53   // good best targets.
54   if (EquallyBest) {
55     Error = std::string("Cannot choose between targets \"") +
56       Best->Name  + "\" and \"" + EquallyBest->Name + "\"";
57     return 0;
58   }
59 
60   return Best;
61 }
62 
RegisterTarget(Target & T,const char * Name,const char * ShortDesc,Target::TripleMatchQualityFnTy TQualityFn,bool HasJIT)63 void TargetRegistry::RegisterTarget(Target &T,
64                                     const char *Name,
65                                     const char *ShortDesc,
66                                     Target::TripleMatchQualityFnTy TQualityFn,
67                                     bool HasJIT) {
68   assert(Name && ShortDesc && TQualityFn &&
69          "Missing required target information!");
70 
71   // Check if this target has already been initialized, we allow this as a
72   // convenience to some clients.
73   if (T.Name)
74     return;
75 
76   // Add to the list of targets.
77   T.Next = FirstTarget;
78   FirstTarget = &T;
79 
80   T.Name = Name;
81   T.ShortDesc = ShortDesc;
82   T.TripleMatchQualityFn = TQualityFn;
83   T.HasJIT = HasJIT;
84 }
85 
getClosestTargetForJIT(std::string & Error)86 const Target *TargetRegistry::getClosestTargetForJIT(std::string &Error) {
87   const Target *TheTarget = lookupTarget(sys::getHostTriple(), Error);
88 
89   if (TheTarget && !TheTarget->hasJIT()) {
90     Error = "No JIT compatible target available for this host";
91     return 0;
92   }
93 
94   return TheTarget;
95 }
96 
TargetArraySortFn(const void * LHS,const void * RHS)97 static int TargetArraySortFn(const void *LHS, const void *RHS) {
98   typedef std::pair<StringRef, const Target*> pair_ty;
99   return ((const pair_ty*)LHS)->first.compare(((const pair_ty*)RHS)->first);
100 }
101 
printRegisteredTargetsForVersion()102 void TargetRegistry::printRegisteredTargetsForVersion() {
103   std::vector<std::pair<StringRef, const Target*> > Targets;
104   size_t Width = 0;
105   for (TargetRegistry::iterator I = TargetRegistry::begin(),
106        E = TargetRegistry::end();
107        I != E; ++I) {
108     Targets.push_back(std::make_pair(I->getName(), &*I));
109     Width = std::max(Width, Targets.back().first.size());
110   }
111   array_pod_sort(Targets.begin(), Targets.end(), TargetArraySortFn);
112 
113   raw_ostream &OS = outs();
114   OS << "  Registered Targets:\n";
115   for (unsigned i = 0, e = Targets.size(); i != e; ++i) {
116     OS << "    " << Targets[i].first;
117     OS.indent(Width - Targets[i].first.size()) << " - "
118       << Targets[i].second->getShortDescription() << '\n';
119   }
120   if (Targets.empty())
121     OS << "    (none)\n";
122 }
123