diff options
Diffstat (limited to 'gold/merge.cc')
| -rw-r--r-- | gold/merge.cc | 39 |
1 files changed, 30 insertions, 9 deletions
diff --git a/gold/merge.cc b/gold/merge.cc index fc6bffb..beb0906 100644 --- a/gold/merge.cc +++ b/gold/merge.cc @@ -49,7 +49,8 @@ class 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(const Merge_map*, unsigned int shndx, section_offset_type offset, section_size_type length, section_offset_type output_offset); @@ -58,7 +59,8 @@ class Object_merge_map // 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. + // 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 Merge_map*, unsigned int shndx, section_offset_type offset, @@ -86,10 +88,28 @@ class Object_merge_map { return i1.input_offset < i2.input_offset; } }; - // A list of entries for a particular section. + // A list of entries for a particular input section. struct Input_merge_map { - // The Merge_map for this section. + // 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 Merge_map* merge_map; // The list of mappings. std::vector<Input_merge_entry> entries; @@ -162,7 +182,7 @@ Object_merge_map::get_or_make_input_merge_map(const Merge_map* merge_map, if (map != NULL) { // For a given input section in a given object, every mapping - // must be donw with the same Merge_map. + // must be done with the same Merge_map. gold_assert(map->merge_map == merge_map); return map; } @@ -277,8 +297,8 @@ Object_merge_map::get_output_offset(const Merge_map* merge_map, // Class Merge_map. // Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in input -// section SHNDX in object OBJECT to an OUTPUT_OFFSET in a merged -// output section. +// section SHNDX in object OBJECT to an OUTPUT_OFFSET in merged data +// in an output section. void Merge_map::add_mapping(Relobj* object, unsigned int shndx, @@ -297,8 +317,9 @@ Merge_map::add_mapping(Relobj* object, unsigned int shndx, // 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 returns -// true if the mapping is known, false otherwise. +// *OUTPUT_OFFSET to the offset in the merged data in the output +// section. This returns true if the mapping is known, false +// otherwise. bool Merge_map::get_output_offset(const Relobj* object, unsigned int shndx, |