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