// 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);
// 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,
{ 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;
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;
}
// 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,
// 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,
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