src/ld/passes/dylibs.cpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
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  24
  25
  26 #include <stdint.h>
  27 #include <math.h>
  28 #include <unistd.h>
  29 #include <dlfcn.h>
  30 #include <mach/machine.h>
  31
  32 #include <vector>
  33 #include <map>
  34
  35 #include "ld.hpp"
  36 #include "dylibs.h"
  37
  38 namespace ld {
  39 namespace passes {
  40 namespace dylibs {
  41
  42
  43 class WillBeUsed
  44 {
  45 public:
  46         bool operator()(ld::dylib::File* dylib) const {
  47                 return dylib->willRemoved();
  48         }
  49 };
  50
  51
  52 void doPass(const Options& opts, ld::Internal& state)
  53 {
  54 //      const bool log = false;
  55
  56         // clear "willRemoved" bit on all dylibs
  57         for (std::vector<ld::dylib::File*>::iterator it = state.dylibs.begin(); it != state.dylibs.end(); ++it) {
  58                 ld::dylib::File* aDylib = *it;
  59                 aDylib->setWillBeRemoved(false);
  60         }
  61         for (std::vector<ld::dylib::File*>::iterator it = state.dylibs.begin(); it != state.dylibs.end(); ++it) {
  62                 ld::dylib::File* aDylib = *it;
  63                 // set "willRemoved" bit on implicit dylibs that did not provide any exports
  64                 if ( aDylib->implicitlyLinked() && !aDylib->explicitlyLinked() && !aDylib->providedExportAtom() )
  65                         aDylib->setWillBeRemoved(true);
  66                 // set "willRemoved" bit on dead strippable explicit dylibs that did not provide any exports
  67                 if ( aDylib->explicitlyLinked() && aDylib->deadStrippable() && !aDylib->providedExportAtom() )
  68                         aDylib->setWillBeRemoved(true);
  69                 // set "willRemoved" bit on any unused explicit when -dead_strip_dylibs is used
  70                 if ( opts.deadStripDylibs() && !aDylib->providedExportAtom() )
  71                         aDylib->setWillBeRemoved(true);
  72         }
  73         // remove unused dylibs
  74         state.dylibs.erase(std::remove_if(state.dylibs.begin(), state.dylibs.end(), WillBeUsed()), state.dylibs.end());
  75
  76
  77         // <rdar://problem/9441273> automatically weak-import dylibs when all symbols from it are weak-imported
  78         for (std::vector<ld::Internal::FinalSection*>::iterator sit=state.sections.begin(); sit != state.sections.end(); ++sit) {
  79                 ld::Internal::FinalSection* sect = *sit;
  80                 for (std::vector<const ld::Atom*>::iterator ait=sect->atoms.begin();  ait != sect->atoms.end(); ++ait) {
  81                         const ld::Atom* atom = *ait;
  82                         const ld::Atom* target = NULL;
  83                         bool targetIsWeakImport = false;
  84                         for (ld::Fixup::iterator fit = atom->fixupsBegin(), end=atom->fixupsEnd(); fit != end; ++fit) {
  85                                 if ( fit->firstInCluster() )
  86                                         target = NULL;
  87                                 switch ( fit->binding ) {
  88                                         case ld::Fixup::bindingsIndirectlyBound:
  89                                                 target = state.indirectBindingTable[fit->u.bindingIndex];
  90                                                 targetIsWeakImport = fit->weakImport;
  91                                                 break;
  92                                         case ld::Fixup::bindingDirectlyBound:
  93                                                 target = fit->u.target;
  94                                                 targetIsWeakImport = fit->weakImport;
  95                                                 break;
  96                     default:
  97                         break;
  98                                 }
  99                                 if ( (target != NULL) && (target->definition() == ld::Atom::definitionProxy) ) {
 100                                         if ( targetIsWeakImport && !opts.allowWeakImports() )
 101                                                 throwf("weak import of symbol '%s' not supported because of option: -no_weak_imports", target->name());
 102                                         ld::Atom::WeakImportState curWI = target->weakImportState();
 103                                         if ( curWI == ld::Atom::weakImportUnset ) {
 104                                                 // first use of this proxy, set weak-import based on this usage
 105                                                 (const_cast<ld::Atom*>(target))->setWeakImportState(targetIsWeakImport);
 106                                         }
 107                                         else {
 108                                                 // proxy already has weak-importness set, check for weakness mismatch
 109                                                 bool curIsWeakImport = (curWI == ld::Atom::weakImportTrue);
 110                                                 if ( curIsWeakImport != targetIsWeakImport ) {
 111                                                         // found mismatch
 112                                                         switch ( opts.weakReferenceMismatchTreatment() ) {
 113                                                                 case Options::kWeakReferenceMismatchError:
 114                                                                         throwf("mismatching weak references for symbol: %s", target->name());
 115                                                                 case Options::kWeakReferenceMismatchWeak:
 116                                                                         (const_cast<ld::Atom*>(target))->setWeakImportState(true);
 117                                                                         break;
 118                                                                 case Options::kWeakReferenceMismatchNonWeak:
 119                                                                         (const_cast<ld::Atom*>(target))->setWeakImportState(false);
 120                                                                         break;
 121                                                         }
 122                                                 }
 123                                         }
 124                                 }
 125                         }
 126                 }
 127         }
 128
 129 }
 130
 131
 132 } // namespace dylibs
 133 } // namespace passes
 134 } // namespace ld