darkkirb/old-cross-binutils
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

AVR/ld: Propagate link-relax elf header flag correctly.

Browse source 
The AVR target has an elf header flag to indicate if an object was
assembler ready for linker relaxation.  If a partial link is performed
then it is important that the link-relax flag in the output object is
set correctly, otherwise, during the final link, we might try to perform
linker relaxation on code that was not assembled suitably.

As the link-relax elf header covers the entire object file we must be
conservative when setting the flag in the output object, so, for a
partial link, any input object that does not have the link-relax flag
set will cause the output object to also not have the link-relax flag
set.

This conservative approach could be softened in future, we only need to
disable the link relax flag if an input file is not marked link-relax
ready, and the input file contains a relaxable section.  However, I've
left this optimisation for a later day.

For the final link I've overloaded the use of the link-relax elf header
flag, in a final executable, the flag now indicates if the executable
was built with linker relaxation on or not.

ld/ChangeLog:

	* emultempl/avrelf.em: Add include of elf/avr.h.
	(avr_finish): New function.
	(LDEMUL_FINISH): Added.

ld/testsuite/ChangeLog:

	* ld-avr/relax-elf-flags-01.d: New file.
	* ld-avr/relax-elf-flags-02.d: New file.
	* ld-avr/relax-elf-flags-03.d: New file.
	* ld-avr/relax-elf-flags-04.d: New file.
	* ld-avr/relax-elf-flags-05.d: New file.
	* ld-avr/relax-elf-flags-06.d: New file.
	* ld-avr/relax-elf-flags-07.d: New file.
	* ld-avr/relax-elf-flags-08.d: New file.
	* ld-avr/relax-elf-flags-a.s: New file.
	* ld-avr/relax-elf-flags-b.s: New file.
This commit is contained in:
Andrew Burgess 2014-11-22 23:25:17 +00:00
parent eac7440d80
commit 9d7b48dc6e
13 changed files with 160 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
ld/ChangeLog
View file

@ -1,3 +1,9 @@
2014-12-23 Andrew Burgess <andrew.burgess@embecosm.com>
* emultempl/avrelf.em: Add include of elf/avr.h.
(avr_finish): New function.
(LDEMUL_FINISH): Added.
2014-12-23 Alan Modra <amodra@gmail.com>
* ldexp.c (update_definedness): Return false if script symbol is

37
ld/emultempl/avrelf.em
View file

@ -28,6 +28,7 @@ fragment <<EOF
#include "elf32-avr.h"
#include "ldctor.h"
#include "elf/avr.h"
/* The fake file and it's corresponding section meant to hold
the linker stubs if needed. */
@ -175,6 +176,41 @@ avr_elf_before_parse (void)
gld${EMULATION_NAME}_before_parse ();
}
static void
avr_finish (void)
{
bfd *abfd;
bfd_boolean avr_link_relax;
if (link_info.relocatable)
{
avr_link_relax = TRUE;
for (abfd = link_info.input_bfds; abfd != NULL; abfd = abfd->link.next)
{
/* Don't let the linker stubs prevent the final object being
marked as link-relax ready. */
if ((elf_elfheader (abfd)->e_flags
& EF_AVR_LINKRELAX_PREPARED) == 0
&& abfd != stub_file->the_bfd)
{
avr_link_relax = FALSE;
break;
}
}
}
else
{
avr_link_relax = RELAXATION_ENABLED;
}
abfd = link_info.output_bfd;
if (avr_link_relax)
elf_elfheader (abfd)->e_flags |= EF_AVR_LINKRELAX_PREPARED;
else
elf_elfheader (abfd)->e_flags &= ~EF_AVR_LINKRELAX_PREPARED;
finish_default ();
}
EOF
@ -274,3 +310,4 @@ LDEMUL_BEFORE_PARSE=avr_elf_before_parse
LDEMUL_BEFORE_ALLOCATION=avr_elf_${EMULATION_NAME}_before_allocation
LDEMUL_AFTER_ALLOCATION=avr_elf_after_allocation
LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS=avr_elf_create_output_section_statements
LDEMUL_FINISH=avr_finish

13
ld/testsuite/ChangeLog
View file

@ -1,3 +1,16 @@
2014-12-23 Andrew Burgess <andrew.burgess@embecosm.com>
* ld-avr/relax-elf-flags-01.d: New file.
* ld-avr/relax-elf-flags-02.d: New file.
* ld-avr/relax-elf-flags-03.d: New file.
* ld-avr/relax-elf-flags-04.d: New file.
* ld-avr/relax-elf-flags-05.d: New file.
* ld-avr/relax-elf-flags-06.d: New file.
* ld-avr/relax-elf-flags-07.d: New file.
* ld-avr/relax-elf-flags-08.d: New file.
* ld-avr/relax-elf-flags-a.s: New file.
* ld-avr/relax-elf-flags-b.s: New file.
2014-12-23 Alan Modra <amodra@gmail.com>
* ld-powerpc/sdabase.s,

12
ld/testsuite/ld-avr/relax-elf-flags-01.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is set on partial link
#as: -mmcu=avrxmega2
#ld: -r -mavrxmega2
#source: relax-elf-flags-a.s -mlink-relax
#source: relax-elf-flags-b.s -mlink-relax
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0xe6, avr:102, link-relax
#...

12
ld/testsuite/ld-avr/relax-elf-flags-02.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is clear on partial link (first file)
#as: -mmcu=avrxmega2
#ld: -r -mavrxmega2
#source: relax-elf-flags-a.s
#source: relax-elf-flags-b.s -mlink-relax
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0x66, avr:102
#...

12
ld/testsuite/ld-avr/relax-elf-flags-03.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is clear on partial link, second file.
#as: -mmcu=avrxmega2
#ld: -r -mavrxmega2
#source: relax-elf-flags-a.s -mlink-relax
#source: relax-elf-flags-b.s
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0x66, avr:102
#...

12
ld/testsuite/ld-avr/relax-elf-flags-04.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is clear on partial link (both files)
#as: -mmcu=avrxmega2
#ld: -r -mavrxmega2
#source: relax-elf-flags-a.s
#source: relax-elf-flags-b.s
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0x66, avr:102
#...

12
ld/testsuite/ld-avr/relax-elf-flags-05.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is set final link (no inputs relaxable)
#as: -mmcu=avrxmega2
#ld: -relax -mavrxmega2
#source: relax-elf-flags-a.s
#source: relax-elf-flags-b.s
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0xe6, avr:102, link-relax
#...

12
ld/testsuite/ld-avr/relax-elf-flags-06.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is set final link (first input relaxable)
#as: -mmcu=avrxmega2
#ld: -relax -mavrxmega2
#source: relax-elf-flags-a.s -mlink-relax
#source: relax-elf-flags-b.s
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0xe6, avr:102, link-relax
#...

12
ld/testsuite/ld-avr/relax-elf-flags-07.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is set final link (both inputs relaxable)
#as: -mmcu=avrxmega2
#ld: -relax -mavrxmega2
#source: relax-elf-flags-a.s -mlink-relax
#source: relax-elf-flags-b.s -mlink-relax
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0xe6, avr:102, link-relax
#...

12
ld/testsuite/ld-avr/relax-elf-flags-08.d Normal file
View file

@ -0,0 +1,12 @@
#name: AVR, check link-relax flag is clear final link (both inputs relaxable)
#as: -mmcu=avrxmega2
#ld: -mavrxmega2
#source: relax-elf-flags-a.s -mlink-relax
#source: relax-elf-flags-b.s -mlink-relax
#readelf: -h
#target: avr-*-*
ELF Header:
#...
Flags: 0x66, avr:102
#...

4
ld/testsuite/ld-avr/relax-elf-flags-a.s Normal file
View file

@ -0,0 +1,4 @@
.text
.global _start
_start:
nop

4
ld/testsuite/ld-avr/relax-elf-flags-b.s Normal file
View file

@ -0,0 +1,4 @@
.text
.global func
func:
nop