gdb/dwarf: pass a file_entry to line_header::file_file_name

In the following patch, there will be some callers of file_file_name
that will already have access to the file_entry object for which they
want the file name.  It would be inefficient to have them pass an index,
only for line_header::file_file_name to re-lookup the same file_entry
object.  Change line_header::file_file_name to accept a file_entry
object reference, instead of an index to look up.

I think this change makes sense in any case.  Callers that have an index
can first obtain a file_entry using line_header::file_name_at or
line_header::file_names.

When passing a file_entry object, we can assume that the file_entry's
index is valid, unlike when passing an index.  So, push the special case
about an invalid index to the sole current caller of file_file_name,
macro_start_file.  I think that error belongs there anyway, since it
specifically talks about "bad file number in macro information".

This requires recording the file index in the file_entry structure, so
add that.

Change-Id: Ic6e44c407539d92b7863d7ba82405ade17f384ad

1 files changed, 7 insertions, 3 deletions

diff --git a/gdb/dwarf2/line-header.h b/gdb/dwarf2/line-header.h
index 32f52c4..e6b52f7 100644
--- a/gdb/dwarf2/line-header.h
+++ b/gdb/dwarf2/line-header.h
@@ -36,9 +36,10 @@ struct file_entry
 {
   file_entry () = default;
 
-  file_entry (const char *name_, dir_index d_index_,
+  file_entry (const char *name_, file_name_index index_, dir_index d_index_,
 	      unsigned int mod_time_, unsigned int length_)
     : name (name_),
+      index (index_),
       d_index (d_index_),
       mod_time (mod_time_),
       length (length_)
@@ -52,6 +53,9 @@ struct file_entry
      owned by debug_line_buffer.  */
   const char *name {};
 
+  /* The index of this file in the file table.  */
+  file_name_index index {};
+
   /* The directory index (1-based).  */
   dir_index d_index {};
 
@@ -168,8 +172,8 @@ struct line_header
   const gdb_byte *statement_program_start {}, *statement_program_end {};
 
   /* Return file name relative to the compilation directory of file
-     number FILE in this object's file name table.  */
-  std::string file_file_name (int file) const;
+     FE in this object's file name table.  */
+  std::string file_file_name (const file_entry &fe) const;
 
   /* Return the compilation directory of the compilation unit in the context of
      which this line header is read.  Return nullptr if non applicable.  */