2007-05-16 19:42:48 +02:00
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// merge.cc -- handle section merging for gold
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2007-09-22 23:02:10 +02:00
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// Copyright 2006, 2007 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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2007-05-16 19:42:48 +02:00
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#include "gold.h"
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#include <cstdlib>
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2007-10-18 19:46:23 +02:00
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#include <algorithm>
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2007-05-16 19:42:48 +02:00
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#include "merge.h"
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namespace gold
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{
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// Sort the entries in a merge mapping. The key is an input object, a
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// section index in that object, and an offset in that section.
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bool
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Output_merge_base::Merge_key_less::operator()(const Merge_key& mk1,
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const Merge_key& mk2) const
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{
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// The order of different objects and different sections doesn't
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// matter. We want to get consistent results across links so we
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// don't use pointer comparison.
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if (mk1.object != mk2.object)
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2007-10-10 08:33:56 +02:00
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{
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// Two different object files can have the same name: if foo.a
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// includes both bar/qux.o and baz/qux.o, then both end up with
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// the name foo.a(qux.o). But it's impossible for two different
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// object files to have both the same name and the same offset.
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if (mk1.object->offset() != mk2.object->offset())
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return mk1.object->offset() < mk2.object->offset();
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return mk1.object->name() < mk2.object->name();
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}
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2007-05-16 19:42:48 +02:00
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if (mk1.shndx != mk2.shndx)
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return mk1.shndx < mk2.shndx;
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return mk1.offset < mk2.offset;
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}
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// Add a mapping from an OFFSET in input section SHNDX in object
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// OBJECT to an OUTPUT_OFFSET in a merged output section. This
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// manages the mapping used to resolve relocations against merged
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// sections.
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void
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Output_merge_base::add_mapping(Relobj* object, unsigned int shndx,
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off_t offset, off_t output_offset)
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{
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Merge_key mk;
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mk.object = object;
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mk.shndx = shndx;
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mk.offset = offset;
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std::pair<Merge_map::iterator, bool> ins =
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this->merge_map_.insert(std::make_pair(mk, output_offset));
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gold_assert(ins.second);
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}
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// Return the output address for an input address. The input address
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// is at offset OFFSET in section SHNDX in OBJECT.
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// OUTPUT_SECTION_ADDRESS is the address of the output section. If we
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// know the address, set *POUTPUT and return true. Otherwise return
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// false.
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bool
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Output_merge_base::do_output_address(const Relobj* object, unsigned int shndx,
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off_t offset,
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uint64_t output_section_address,
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uint64_t* poutput) const
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{
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gold_assert(output_section_address == this->address());
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Merge_key mk;
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mk.object = object;
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mk.shndx = shndx;
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mk.offset = offset;
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Merge_map::const_iterator p = this->merge_map_.lower_bound(mk);
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// If MK is not in the map, lower_bound returns the next iterator
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// larger than it.
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2007-09-23 05:16:47 +02:00
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if (p == this->merge_map_.end()
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|| p->first.object != object
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2007-05-16 19:42:48 +02:00
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|| p->first.shndx != shndx
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|| p->first.offset != offset)
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{
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if (p == this->merge_map_.begin())
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return false;
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--p;
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}
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if (p->first.object != object || p->first.shndx != shndx)
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return false;
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// Any input section is fully mapped: we don't need to know the size
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// of the range starting at P->FIRST.OFFSET.
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*poutput = output_section_address + p->second + (offset - p->first.offset);
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return true;
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}
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// Compute the hash code for a fixed-size constant.
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size_t
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Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const
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{
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const unsigned char* p = this->pomd_->constant(k);
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uint64_t entsize = this->pomd_->entsize();
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// Fowler/Noll/Vo (FNV) hash (type FNV-1a).
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if (sizeof(size_t) == 8)
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{
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size_t result = static_cast<size_t>(14695981039346656037ULL);
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for (uint64_t i = 0; i < entsize; ++i)
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{
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result &= (size_t) *p++;
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result *= 1099511628211ULL;
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}
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return result;
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}
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else
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{
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size_t result = 2166136261UL;
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for (uint64_t i = 0; i < entsize; ++i)
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{
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result ^= (size_t) *p++;
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result *= 16777619UL;
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}
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return result;
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}
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}
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// Return whether one hash table key equals another.
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bool
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Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1,
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Merge_data_key k2) const
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{
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const unsigned char* p1 = this->pomd_->constant(k1);
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const unsigned char* p2 = this->pomd_->constant(k2);
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return memcmp(p1, p2, this->pomd_->entsize()) == 0;
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}
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// Add a constant to the end of the section contents.
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void
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Output_merge_data::add_constant(const unsigned char* p)
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{
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uint64_t entsize = this->entsize();
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2007-10-18 19:46:23 +02:00
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uint64_t addsize = std::max(entsize, this->addralign());
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if (this->len_ + addsize > this->alc_)
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2007-05-16 19:42:48 +02:00
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{
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if (this->alc_ == 0)
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2007-10-18 19:46:23 +02:00
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this->alc_ = 128 * addsize;
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2007-05-16 19:42:48 +02:00
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else
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this->alc_ *= 2;
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this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_));
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if (this->p_ == NULL)
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2007-10-14 08:49:14 +02:00
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gold_nomem();
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2007-05-16 19:42:48 +02:00
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}
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memcpy(this->p_ + this->len_, p, entsize);
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2007-10-18 19:46:23 +02:00
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if (addsize > entsize)
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memset(this->p_ + this->len_ + entsize, 0, addsize - entsize);
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this->len_ += addsize;
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2007-05-16 19:42:48 +02:00
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}
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// Add the input section SHNDX in OBJECT to a merged output section
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// which holds fixed length constants. Return whether we were able to
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// handle the section; if not, it will be linked as usual without
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// constant merging.
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bool
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Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx)
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{
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off_t len;
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2007-09-25 19:50:26 +02:00
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const unsigned char* p = object->section_contents(shndx, &len, false);
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2007-05-16 19:42:48 +02:00
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uint64_t entsize = this->entsize();
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if (len % entsize != 0)
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return false;
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for (off_t i = 0; i < len; i += entsize, p += entsize)
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{
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// Add the constant to the section contents. If we find that it
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// is already in the hash table, we will remove it again.
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Merge_data_key k = this->len_;
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this->add_constant(p);
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std::pair<Merge_data_hashtable::iterator, bool> ins =
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this->hashtable_.insert(k);
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if (!ins.second)
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{
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// Key was already present. Remove the copy we just added.
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this->len_ -= entsize;
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k = *ins.first;
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}
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// Record the offset of this constant in the output section.
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this->add_mapping(object, shndx, i, k);
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}
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return true;
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}
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// Set the final data size in a merged output section with fixed size
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// constants.
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void
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Output_merge_data::do_set_address(uint64_t, off_t)
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{
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// Release the memory we don't need.
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this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_));
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gold_assert(this->p_ != NULL);
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this->set_data_size(this->len_);
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}
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// Write the data of a merged output section with fixed size constants
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// to the file.
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void
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Output_merge_data::do_write(Output_file* of)
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{
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of->write(this->offset(), this->p_, this->len_);
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}
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// Add an input section to a merged string section.
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template<typename Char_type>
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bool
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Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
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unsigned int shndx)
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{
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off_t len;
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2007-09-25 19:50:26 +02:00
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const unsigned char* pdata = object->section_contents(shndx, &len, false);
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2007-05-16 19:42:48 +02:00
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const Char_type* p = reinterpret_cast<const Char_type*>(pdata);
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if (len % sizeof(Char_type) != 0)
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{
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2007-10-14 08:49:14 +02:00
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object->error(_("mergeable string section length not multiple of "
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"character size"));
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return false;
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2007-05-16 19:42:48 +02:00
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}
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2007-10-20 01:33:37 +02:00
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// The index I is in bytes, not characters.
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2007-05-16 19:42:48 +02:00
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off_t i = 0;
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while (i < len)
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{
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off_t plen = 0;
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for (const Char_type* pl = p; *pl != 0; ++pl)
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{
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2007-10-20 01:33:37 +02:00
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// The length PLEN is in characters, not bytes.
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2007-05-16 19:42:48 +02:00
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++plen;
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2007-10-20 06:35:43 +02:00
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if (i + plen * static_cast<off_t>(sizeof(Char_type)) >= len)
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2007-05-16 19:42:48 +02:00
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{
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2007-10-14 08:49:14 +02:00
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object->error(_("entry in mergeable string section "
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"not null terminated"));
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break;
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2007-05-16 19:42:48 +02:00
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}
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}
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2007-10-12 08:06:34 +02:00
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const Char_type* str = this->stringpool_.add(p, true, NULL);
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2007-05-16 19:42:48 +02:00
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2007-09-22 07:38:12 +02:00
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this->merged_strings_.push_back(Merged_string(object, shndx, i, str));
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2007-05-16 19:42:48 +02:00
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p += plen + 1;
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2007-10-20 01:33:37 +02:00
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i += (plen + 1) * sizeof(Char_type);
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2007-05-16 19:42:48 +02:00
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}
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return true;
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}
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// Set the final data size of a merged string section. This is where
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// we finalize the mappings from the input sections to the output
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// section.
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template<typename Char_type>
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void
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Output_merge_string<Char_type>::do_set_address(uint64_t, off_t)
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{
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this->stringpool_.set_string_offsets();
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2007-09-22 07:38:12 +02:00
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for (typename Merged_strings::const_iterator p =
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this->merged_strings_.begin();
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p != this->merged_strings_.end();
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2007-05-16 19:42:48 +02:00
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++p)
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2007-09-22 07:38:12 +02:00
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this->add_mapping(p->object, p->shndx, p->offset,
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this->stringpool_.get_offset(p->string));
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2007-05-16 19:42:48 +02:00
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this->set_data_size(this->stringpool_.get_strtab_size());
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// Save some memory.
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2007-09-22 07:38:12 +02:00
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this->merged_strings_.clear();
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2007-05-16 19:42:48 +02:00
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}
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// Write out a merged string section.
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template<typename Char_type>
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void
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Output_merge_string<Char_type>::do_write(Output_file* of)
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{
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this->stringpool_.write(of, this->offset());
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}
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// Instantiate the templates we need.
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template
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class Output_merge_string<char>;
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template
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class Output_merge_string<uint16_t>;
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template
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class Output_merge_string<uint32_t>;
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} // End namespace gold.
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