src/ld/passes/huge.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
  34 #include "ld.hpp"
  35 #include "huge.h"
  36
  37 namespace ld {
  38 namespace passes {
  39 namespace huge {
  40
  41 class NullAtom
  42 {
  43 public:
  44         bool operator()(const ld::Atom* atom) const {
  45                 return (atom == NULL);
  46         }
  47 };
  48
  49 void doPass(const Options& opts, ld::Internal& state)
  50 {
  51         const bool log = false;
  52
  53         // only make make __huge section in final linked images
  54         if ( opts.outputKind() == Options::kObjectFile )
  55                 return;
  56
  57         // only make make __huge section for x86_64
  58         if ( opts.architecture() != CPU_TYPE_X86_64 )
  59                 return;
  60
  61         // only needed if some (non-linkedit) atoms have an addresss >2GB from base address
  62         state.usingHugeSections = false;
  63         uint64_t address = 0;
  64         for (std::vector<ld::Internal::FinalSection*>::iterator sit=state.sections.begin(); sit != state.sections.end(); ++sit) {
  65                 ld::Internal::FinalSection* sect = *sit;
  66                 if ( sect->type() == ld::Section::typePageZero )
  67                         continue;
  68                 if ( sect->type() == ld::Section::typeStack )
  69                         continue;
  70                 for (std::vector<const ld::Atom*>::iterator ait=sect->atoms.begin(); ait != sect->atoms.end(); ++ait) {
  71                         const ld::Atom* atom = *ait;
  72                         if ( (address > 0x7FFFFFFFLL) && !sect->isSectionHidden() ) {
  73                                 state.usingHugeSections = true;
  74                                 if (log) fprintf(stderr, "atom: %s is >2GB (0x%09llX), so enabling huge mode\n", atom->name(), address);
  75                                 break;
  76                         }
  77                         address += atom->size();
  78                 }
  79                 if ( state.usingHugeSections )
  80                         break;
  81         }
  82         if ( !state.usingHugeSections )
  83                 return;
  84
  85         // move all zero fill atoms that >1MB in size to a new __huge section
  86         ld::Internal::FinalSection* hugeSection = state.getFinalSection(*new ld::Section("__DATA", "__huge", ld::Section::typeZeroFill));
  87         for (std::vector<ld::Internal::FinalSection*>::iterator sit=state.sections.begin(); sit != state.sections.end(); ++sit) {
  88                 ld::Internal::FinalSection* sect = *sit;
  89                 if ( sect == hugeSection )
  90                         continue;
  91                 if ( sect->type() == ld::Section::typeZeroFill ) {
  92                         bool movedSome = false;
  93                         for (std::vector<const ld::Atom*>::iterator ait=sect->atoms.begin(); ait != sect->atoms.end(); ++ait) {
  94                                 const ld::Atom* atom = *ait;
  95                                 if ( atom->size() > 1024*1024 ) {
  96                                         hugeSection->atoms.push_back(atom);
  97                                         if (log) fprintf(stderr, "moved to __huge: %s, size=%llu\n", atom->name(), atom->size());
  98                                         *ait = NULL;  // change atom to NULL for later bulk removal
  99                                         movedSome = true;
 100                                 }
 101                         }
 102                         if ( movedSome )
 103                                 sect->atoms.erase(std::remove_if(sect->atoms.begin(), sect->atoms.end(), NullAtom()), sect->atoms.end());
 104                 }
 105         }
 106
 107
 108 }
 109
 110
 111 } // namespace huge
 112 } // namespace passes
 113 } // namespace ld