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authorIan Lance Taylor <iant@google.com>2007-05-16 17:42:48 +0000
committerIan Lance Taylor <iant@google.com>2007-05-16 17:42:48 +0000
commitb8e6aad9606384125f588d531c567f49bad346e2 (patch)
treee1172d50384713b91c329cc88cabcd2728f929a9 /gold/merge.h
parent60dfee729999b913a247956c4816e758afb86a4b (diff)
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Add support for SHF_MERGE sections.
Diffstat (limited to 'gold/merge.h')
-rw-r--r--gold/merge.h226
1 files changed, 226 insertions, 0 deletions
diff --git a/gold/merge.h b/gold/merge.h
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+// merge.h -- handle section merging for gold -*- C++ -*-
+
+#ifndef GOLD_MERGE_H
+#define GOLD_MERGE_H
+
+#include <climits>
+
+#include "stringpool.h"
+#include "output.h"
+
+namespace gold
+{
+
+// A general class for SHF_MERGE data, to hold functions shared by
+// fixed-size constant data and string data.
+
+class Output_merge_base : public Output_section_data
+{
+ public:
+ Output_merge_base(uint64_t entsize)
+ : Output_section_data(1), merge_map_(), entsize_(entsize)
+ { }
+
+ // Return the output address for an input address.
+ bool
+ do_output_address(const Relobj* object, unsigned int shndx, off_t offset,
+ uint64_t output_section_address, uint64_t* 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.
+ void
+ add_mapping(Relobj* object, unsigned int shndx, off_t offset,
+ off_t output_offset);
+
+ private:
+ // We build a mapping from OBJECT/SHNDX/OFFSET to an offset in the
+ // output section.
+ struct Merge_key
+ {
+ const Relobj* object;
+ unsigned int shndx;
+ off_t offset;
+ };
+
+ struct Merge_key_less
+ {
+ bool
+ operator()(const Merge_key&, const Merge_key&) const;
+ };
+
+ typedef std::map<Merge_key, off_t, Merge_key_less> Merge_map;
+
+ // 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_;
+};
+
+// Handle SHF_MERGE sections with fixed-size constant data.
+
+class Output_merge_data : public Output_merge_base
+{
+ public:
+ Output_merge_data(uint64_t entsize)
+ : Output_merge_base(entsize), p_(NULL), len_(0), alc_(0),
+ hashtable_(128, Merge_data_hash(this), Merge_data_eq(this))
+ { }
+
+ // Add an input section.
+ bool
+ do_add_input_section(Relobj* object, unsigned int shndx);
+
+ // Set the final data size.
+ void
+ do_set_address(uint64_t, off_t);
+
+ // Write the data to the file.
+ void
+ do_write(Output_file*);
+
+ 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.
+
+ // A key in the hash table. This is an offset in the section
+ // contents we are building.
+ typedef off_t Merge_data_key;
+
+ // Compute the hash code. To do this we need a pointer back to the
+ // object holding the data.
+ class Merge_data_hash
+ {
+ public:
+ Merge_data_hash(const Output_merge_data* pomd)
+ : pomd_(pomd)
+ { }
+
+ size_t
+ operator()(Merge_data_key) const;
+
+ private:
+ const Output_merge_data* pomd_;
+ };
+
+ friend class Merge_data_hash;
+
+ // Compare two entries in the hash table for equality. To do this
+ // we need a pointer back to the object holding the data. Note that
+ // we now have a pointer to the object stored in two places in the
+ // hash table. Fixing this would require specializing the hash
+ // table, which would be hard to do portably.
+ class Merge_data_eq
+ {
+ public:
+ Merge_data_eq(const Output_merge_data* pomd)
+ : pomd_(pomd)
+ { }
+
+ bool
+ operator()(Merge_data_key k1, Merge_data_key k2) const;
+
+ private:
+ const Output_merge_data* pomd_;
+ };
+
+ friend class Merge_data_eq;
+
+ // The type of the hash table.
+ typedef Unordered_set<Merge_data_key, Merge_data_hash, Merge_data_eq>
+ Merge_data_hashtable;
+
+ // Given a hash table key, which is just an offset into the section
+ // data, return a pointer to the corresponding constant.
+ const unsigned char*
+ constant(Merge_data_key k) const
+ {
+ gold_assert(k >= 0 && k < this->len_);
+ return this->p_ + k;
+ }
+
+ // Add a constant to the output.
+ void
+ add_constant(const unsigned char*);
+
+ // The accumulated data.
+ unsigned char* p_;
+ // The length of the accumulated data.
+ off_t len_;
+ // The size of the allocated buffer.
+ size_t alc_;
+ // The hash table.
+ Merge_data_hashtable hashtable_;
+};
+
+// Handle SHF_MERGE sections with string data. This is a template
+// based on the type of the characters in the string.
+
+template<typename Char_type>
+class Output_merge_string : public Output_merge_base
+{
+ public:
+ Output_merge_string()
+ : Output_merge_base(sizeof(Char_type)), stringpool_(false), hashtable_()
+ { }
+
+ // Add an input section.
+ bool
+ do_add_input_section(Relobj* object, unsigned int shndx);
+
+ // Set the final data size.
+ void
+ do_set_address(uint64_t, off_t);
+
+ // Write the data to the file.
+ void
+ do_write(Output_file*);
+
+ private:
+ // As we see input sections, we build a mapping from object, section
+ // index and offset to strings.
+ struct Merge_string_key
+ {
+ Relobj* object;
+ unsigned int shndx;
+ off_t offset;
+
+ Merge_string_key(Relobj *objecta, unsigned int shndxa, off_t offseta)
+ : object(objecta), shndx(shndxa), offset(offseta)
+ { }
+ };
+
+ struct Merge_string_key_hash
+ {
+ size_t
+ operator()(const Merge_string_key&) const;
+ };
+
+ struct Merge_string_key_eq
+ {
+ bool
+ operator()(const Merge_string_key&, const Merge_string_key&) const;
+ };
+
+ typedef Unordered_map<Merge_string_key, const Char_type*,
+ Merge_string_key_hash, Merge_string_key_eq>
+ Merge_string_hashtable;
+
+ // 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.
+ Merge_string_hashtable hashtable_;
+};
+
+} // End namespace gold.
+
+#endif // !defined(GOLD_MERGE_H)