// merge.h -- handle section merging for gold -*- C++ -*-
-// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Copyright (C) 2006-2020 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
#define GOLD_MERGE_H
#include <climits>
+#include <map>
+#include <vector>
#include "stringpool.h"
#include "output.h"
namespace gold
{
-// This class manages mappings from input sections to offsets in an
-// output section. This is used where input sections are merged. The
-// actual data is stored in fields in Object.
+// For each object with merge sections, we store an Object_merge_map.
+// This is used to map locations in input sections to a merged output
+// section. The output section itself is not recorded here--it can be
+// found in the output_sections_ field of the Object.
-class Merge_map
+class Object_merge_map
{
public:
- Merge_map()
+ Object_merge_map()
+ : section_merge_maps_()
{ }
- // Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in the
- // input section SHNDX in object OBJECT to OUTPUT_OFFSET in the
+ ~Object_merge_map();
+
+ // Add a mapping for MERGE_MAP, for the bytes from OFFSET to OFFSET
+ // + LENGTH in the input section SHNDX to OUTPUT_OFFSET in the
// output section. An OUTPUT_OFFSET of -1 means that the bytes are
- // discarded.
+ // discarded. OUTPUT_OFFSET is relative to the start of the merged
+ // data in the output section.
void
- add_mapping(Relobj* object, unsigned int shndx,
- section_offset_type offset, section_size_type length,
- section_offset_type output_offset);
-
- // Return the output offset for an input address. The input address
- // is at offset OFFSET in section SHNDX in OBJECT. This sets
- // *OUTPUT_OFFSET to the offset in the output section; this will be
- // -1 if the bytes are not being copied to the output. This returns
- // true if the mapping is known, false otherwise.
+ add_mapping(const Output_section_data*, unsigned int shndx,
+ section_offset_type offset, section_size_type length,
+ section_offset_type output_offset);
+
+ // Get the output offset for an input address. MERGE_MAP is the map
+ // we are looking for, or NULL if we don't care. The input address
+ // is at offset OFFSET in section SHNDX. This sets *OUTPUT_OFFSET
+ // to the offset in the output section; this will be -1 if the bytes
+ // are not being copied to the output. This returns true if the
+ // mapping is known, false otherwise. *OUTPUT_OFFSET is relative to
+ // the start of the merged data in the output section.
bool
- get_output_offset(const Relobj* object, unsigned int shndx,
+ get_output_offset(unsigned int shndx,
section_offset_type offset,
- section_offset_type *output_offset) const;
+ section_offset_type* output_offset);
+
+ const Output_section_data*
+ find_merge_section(unsigned int shndx) const;
+
+ // Initialize an mapping from input offsets to output addresses for
+ // section SHNDX. STARTING_ADDRESS is the output address of the
+ // merged section.
+ template<int size>
+ void
+ initialize_input_to_output_map(
+ unsigned int shndx,
+ typename elfcpp::Elf_types<size>::Elf_Addr starting_address,
+ Unordered_map<section_offset_type,
+ typename elfcpp::Elf_types<size>::Elf_Addr>*);
+
+ // Map input section offsets to a length and an output section
+ // offset. An output section offset of -1 means that this part of
+ // the input section is being discarded.
+ struct Input_merge_entry
+ {
+ // The offset in the input section.
+ section_offset_type input_offset;
+ // The length.
+ section_size_type length;
+ // The offset in the output section.
+ section_offset_type output_offset;
+ };
+
+ // A list of entries for a particular input section.
+ struct Input_merge_map
+ {
+ void add_mapping(section_offset_type input_offset, section_size_type length,
+ section_offset_type output_offset);
+
+ typedef std::vector<Input_merge_entry> Entries;
+
+ // We store these with the Relobj, and we look them up by input
+ // section. It is possible to have two different merge maps
+ // associated with a single output section. For example, this
+ // happens routinely with .rodata, when merged string constants
+ // and merged fixed size constants are both put into .rodata. The
+ // output offset that we store is not the offset from the start of
+ // the output section; it is the offset from the start of the
+ // merged data in the output section. That means that the caller
+ // is going to add the offset of the merged data within the output
+ // section, which means that the caller needs to know which set of
+ // merged data it found the entry in. So it's not enough to find
+ // this data based on the input section and the output section; we
+ // also have to find it based on a set of merged data in the
+ // output section. In order to verify that we are looking at the
+ // right data, we store a pointer to the Merge_map here, and we
+ // pass in a pointer when looking at the data. If we are asked to
+ // look up information for a different Merge_map, we report that
+ // we don't have it, rather than trying a lookup and returning an
+ // answer which will receive the wrong offset.
+ const Output_section_data* output_data;
+ // The list of mappings.
+ Entries entries;
+ // Whether the ENTRIES field is sorted by input_offset.
+ bool sorted;
+
+ Input_merge_map()
+ : output_data(NULL), entries(), sorted(true)
+ { }
+ };
+
+ // Get or make the Input_merge_map to use for the section SHNDX
+ // with MERGE_MAP.
+ Input_merge_map*
+ get_or_make_input_merge_map(const Output_section_data* merge_map,
+ unsigned int shndx);
+
+ private:
+ // A less-than comparison routine for Input_merge_entry.
+ struct Input_merge_compare
+ {
+ bool
+ operator()(const Input_merge_entry& i1, const Input_merge_entry& i2) const
+ { return i1.input_offset < i2.input_offset; }
+ };
+
+ // Map input section indices to merge maps.
+ typedef std::vector<std::pair<unsigned int, Input_merge_map*> >
+ Section_merge_maps;
+
+ // Return a pointer to the Input_merge_map to use for the input
+ // section SHNDX, or NULL.
+ const Input_merge_map*
+ get_input_merge_map(unsigned int shndx) const;
+
+ Input_merge_map *
+ get_input_merge_map(unsigned int shndx) {
+ return const_cast<Input_merge_map *>(static_cast<const Object_merge_map *>(
+ this)->get_input_merge_map(shndx));
+ }
+
+ Section_merge_maps section_merge_maps_;
};
// A general class for SHF_MERGE data, to hold functions shared by
{
public:
Output_merge_base(uint64_t entsize, uint64_t addralign)
- : Output_section_data(addralign), merge_map_(), entsize_(entsize)
+ : Output_section_data(addralign), entsize_(entsize),
+ keeps_input_sections_(false), first_relobj_(NULL), first_shndx_(-1),
+ input_sections_()
{ }
- // Return the output offset for an input offset.
- bool
- do_output_offset(const Relobj* object, unsigned int shndx,
- section_offset_type offset,
- section_offset_type* poutput) const;
-
- protected:
// Return the entry size.
uint64_t
entsize() const
{ return this->entsize_; }
- // Add a mapping from an OFFSET in input section SHNDX in object
- // OBJECT to an OUTPUT_OFFSET in the output section.
+ // Whether this is a merge string section. This is only true of
+ // Output_merge_string.
+ bool
+ is_string()
+ { return this->do_is_string(); }
+
+ // Whether this keeps input sections.
+ bool
+ keeps_input_sections() const
+ { return this->keeps_input_sections_; }
+
+ // Set the keeps-input-sections flag. This is virtual so that sub-classes
+ // can perform additional checks.
void
- add_mapping(Relobj* object, unsigned int shndx, section_offset_type offset,
- section_size_type length, section_offset_type output_offset)
+ set_keeps_input_sections()
+ { this->do_set_keeps_input_sections(); }
+
+ // Return the object of the first merged input section. This used
+ // for script processing. This is NULL if merge section is empty.
+ Relobj*
+ first_relobj() const
+ { return this->first_relobj_; }
+
+ // Return the section index of the first merged input section. This
+ // is used for script processing. This is valid only if merge section
+ // is not valid.
+ unsigned int
+ first_shndx() const
+ {
+ gold_assert(this->first_relobj_ != NULL);
+ return this->first_shndx_;
+ }
+
+ // Set of merged input sections.
+ typedef Unordered_set<Section_id, Section_id_hash> Input_sections;
+
+ // Beginning of merged input sections.
+ Input_sections::const_iterator
+ input_sections_begin() const
{
- this->merge_map_.add_mapping(object, shndx, offset, length, output_offset);
+ gold_assert(this->keeps_input_sections_);
+ return this->input_sections_.begin();
}
+ // Beginning of merged input sections.
+ Input_sections::const_iterator
+ input_sections_end() const
+ {
+ gold_assert(this->keeps_input_sections_);
+ return this->input_sections_.end();
+ }
+
+ protected:
+ // Return the output offset for an input offset.
+ bool
+ do_output_offset(const Relobj* object, unsigned int shndx,
+ section_offset_type offset,
+ section_offset_type* poutput) const;
+
+ // This may be overridden by the child class.
+ virtual bool
+ do_is_string()
+ { return false; }
+
+ // This may be overridden by the child class.
+ virtual void
+ do_set_keeps_input_sections()
+ { this->keeps_input_sections_ = true; }
+
+ // Record the merged input section for script processing.
+ void
+ record_input_section(Relobj* relobj, unsigned int shndx);
+
private:
- // A mapping from input object/section/offset to offset in output
- // section.
- Merge_map merge_map_;
// The entry size. For fixed-size constants, this is the size of
// the constants. For strings, this is the size of a character.
uint64_t entsize_;
+ // Whether we keep input sections.
+ bool keeps_input_sections_;
+ // Object of the first merged input section. We use this for script
+ // processing.
+ Relobj* first_relobj_;
+ // Section index of the first merged input section.
+ unsigned int first_shndx_;
+ // Input sections. We only keep them is keeps_input_sections_ is true.
+ Input_sections input_sections_;
};
// Handle SHF_MERGE sections with fixed-size constant data.
void
do_write_to_buffer(unsigned char*);
+ // Write to a map file.
+ void
+ do_print_to_mapfile(Mapfile* mapfile) const
+ { mapfile->print_output_data(this, _("** merge constants")); }
+
// Print merge stats to stderr.
void
do_print_merge_stats(const char* section_name);
+ // Set keeps-input-sections flag.
+ void
+ do_set_keeps_input_sections()
+ {
+ gold_assert(this->input_count_ == 0);
+ Output_merge_base::do_set_keeps_input_sections();
+ }
+
private:
// We build a hash table of the fixed-size constants. Each constant
// is stored as a pointer into the section data we are accumulating.
{
public:
Output_merge_string(uint64_t addralign)
- : Output_merge_base(sizeof(Char_type), addralign), stringpool_(),
- merged_strings_(), input_count_(0)
+ : Output_merge_base(sizeof(Char_type), addralign), stringpool_(addralign),
+ merged_strings_lists_(), input_count_(0), input_size_(0)
{
- gold_assert(addralign <= sizeof(Char_type));
this->stringpool_.set_no_zero_null();
}
void
do_write_to_buffer(unsigned char*);
+ // Write to a map file.
+ void
+ do_print_to_mapfile(Mapfile* mapfile) const
+ { mapfile->print_output_data(this, _("** merge strings")); }
+
// Print merge stats to stderr.
void
do_print_merge_stats(const char* section_name);
clear_stringpool()
{ this->stringpool_.clear(); }
+ // Whether this is a merge string section.
+ virtual bool
+ do_is_string()
+ { return true; }
+
+ // Set keeps-input-sections flag.
+ void
+ do_set_keeps_input_sections()
+ {
+ gold_assert(this->input_count_ == 0);
+ Output_merge_base::do_set_keeps_input_sections();
+ }
+
private:
// The name of the string type, for stats.
const char*
// index and offset to strings.
struct Merged_string
{
- // The input object where the string was found.
- Relobj* object;
- // The input section in the input object.
- unsigned int shndx;
// The offset in the input section.
section_offset_type offset;
- // The string itself, a pointer into a Stringpool.
- const Char_type* string;
- // The length of the string in bytes, including the null terminator.
- size_t length;
-
- Merged_string(Relobj *objecta, unsigned int shndxa,
- section_offset_type offseta, const Char_type* stringa,
- size_t lengtha)
- : object(objecta), shndx(shndxa), offset(offseta), string(stringa),
- length(lengtha)
+ // The key in the Stringpool.
+ Stringpool::Key stringpool_key;
+
+ Merged_string(section_offset_type offseta, Stringpool::Key stringpool_keya)
+ : offset(offseta), stringpool_key(stringpool_keya)
{ }
};
typedef std::vector<Merged_string> Merged_strings;
+ struct Merged_strings_list
+ {
+ // The input object where the strings were found.
+ Relobj* object;
+ // The input section in the input object.
+ unsigned int shndx;
+ // The list of merged strings.
+ Merged_strings merged_strings;
+
+ Merged_strings_list(Relobj* objecta, unsigned int shndxa)
+ : object(objecta), shndx(shndxa), merged_strings()
+ { }
+ };
+
+ typedef std::vector<Merged_strings_list*> Merged_strings_lists;
+
// As we see the strings, we add them to a Stringpool.
Stringpool_template<Char_type> stringpool_;
// Map from a location in an input object to an entry in the
// Stringpool.
- Merged_strings merged_strings_;
+ Merged_strings_lists merged_strings_lists_;
// The number of entries seen in input files.
size_t input_count_;
+ // The total size of input sections.
+ size_t input_size_;
};
} // End namespace gold.
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