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

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.

1 files changed, 37 insertions, 0 deletions

diff --git a/ld/emultempl/avrelf.em b/ld/emultempl/avrelf.em
index 170dc3e3743..f4e26548019 100644
--- a/ld/emultempl/avrelf.em
+++ b/ld/emultempl/avrelf.em
@@ -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