Delay setting up compressed debug section names

When we set up st_name for output section name in elf_fake_sections, we
don't know if the compressed DWARF debug section will be smaller. We may
end up with compressed DWARF debug sections which are bigger than the
uncompressed ones.  This patch delays setting up st_name for output DWARF
debug section to _bfd_elf_assign_file_positions_for_non_load which will
compress the output debug section.  We also postpone placement of shstrtab
section after DWARF debug sections have been compressed.  The net effect
is .shstrtab section is now placed after .symtab and .strtab sections.

bfd/

	PR ld/18277
	* compress.c (bfd_compress_section_contents): Remove the
	write_compress argument.
	(bfd_init_section_compress_status): Updated.
	(bfd_compress_section): Likewise.
	* elf.c (_bfd_elf_set_reloc_sh_name): New.
	(_bfd_elf_init_reloc_shdr): Add delay_st_name_p.  Set sh_name
	to (unsigned int) -1 if delay_st_name_p is TRUE.  Use
	_bfd_elf_set_reloc_sh_name.
	(elf_fake_sections): Don't rename DWARF debug section for
	linker output if it will be compressed.  Instead, set
	delay_st_name_p to TRUE and pass it to _bfd_elf_init_reloc_shdr.
	(assign_section_numbers): Call _bfd_elf_strtab_addref only if
	sh_name != (unsigned int) -1.  Don't finalize nor assign
	shstrtab section here.  Delay setting output section names to
	_bfd_elf_write_object_contents.
	(_bfd_elf_compute_section_file_positions): Update comments on
	sh_offset for shstrtab section.
	(assign_file_positions_for_non_load_sections): Set sh_offset to
	-1 for shstrtab section.
	(assign_file_positions_except_relocs): Likewise.
	(_bfd_elf_assign_file_positions_for_non_load): Set up sh_name
	when compressing DWARF debug sections.  Place shstrtab section
	after DWARF debug sections have been compressed.
	(_bfd_elf_write_object_contents): Setting sh_name for output
	sections.

ld/testsuite/

	PR ld/18277
	* ld-elf/compressed1d.d: New.
	* ld-elf/compressed1e.d: Likewise.

1 files changed, 5 insertions, 10 deletions

diff --git a/bfd/compress.c b/bfd/compress.c
index dfde50e81c6..d0f745fe6e1 100644
--- a/bfd/compress.c
+++ b/bfd/compress.c
@@ -72,8 +72,7 @@ decompress_contents (bfd_byte *compressed_buffer,
 static bfd_size_type
 bfd_compress_section_contents (bfd *abfd, sec_ptr sec,
 			       bfd_byte *uncompressed_buffer,
-			       bfd_size_type uncompressed_size,
-			       bfd_boolean write_compress)
+			       bfd_size_type uncompressed_size)
 {
   uLong compressed_size;
   bfd_byte *buffer;
@@ -177,11 +176,8 @@ bfd_compress_section_contents (bfd *abfd, sec_ptr sec,
 
       compressed_size += header_size;
       /* PR binutils/18087: If compression didn't make the section smaller,
-	 just keep it uncompressed.  We always generate .zdebug_* section
-	 when linking since section names have been finalized and they
-	 can't be changed easily.  */
-      if ((write_compress && compression_header_size == 0)
-	   || compressed_size < uncompressed_size)
+	 just keep it uncompressed.  */
+      if (compressed_size < uncompressed_size)
 	{
 	  bfd_update_compression_header (abfd, buffer, sec);
 
@@ -547,8 +543,7 @@ bfd_init_section_compress_status (bfd *abfd, sec_ptr sec)
     {
       uncompressed_size = bfd_compress_section_contents (abfd, sec,
 							 uncompressed_buffer,
-							 uncompressed_size,
-							 FALSE);
+							 uncompressed_size);
       ret = uncompressed_size != 0;
     }
 
@@ -590,5 +585,5 @@ bfd_compress_section (bfd *abfd, sec_ptr sec, bfd_byte *uncompressed_buffer)
 
   /* Compress it.  */
   return bfd_compress_section_contents (abfd, sec, uncompressed_buffer,
-					uncompressed_size, TRUE) != 0;
+					uncompressed_size) != 0;
 }