[binutils-gdb] bfd: allow negative offsets to _GLOBAL_OFFSET_TABLE_ in elf64 SPARC

[Jose E.Marchesi <jemarch at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b19753ce31da347605dfa903c6fd2158e2444f0d

commit b19753ce31da347605dfa903c6fd2158e2444f0d
Author: Jose E. Marchesi <jose.marchesi@oracle.com>
Date:   Mon Sep 19 05:19:14 2016 -0700

    bfd: allow negative offsets to _GLOBAL_OFFSET_TABLE_ in elf64 SPARC
    
    The code compiled with the -fpic model in SPARC uses 13-bit signed
    immediate PC-relative loads to fetch entries from the GOT table.  In
    theory this would allow using a GOT table (.got section) containing up
    to 1024 entries in elf32 or 512 entries in elf64.
    
    However, in elf64 sparc GNU targets _GLOBAL_OFFSET_TABLE_ is always
    placed at the beginning of the .got section, making it impossible to use
    negative offsets.  This limits the usage of -fpic to GOT tables
    containing a maximum of 257 entries in elf64.
    
    This patch activates an optimization that is already used in sparc-elf32
    also in sparc-elf64, that sets _GLOBAL_OFFSET_TABLE_ to point 0x1000
    into the .got section if the section size is bigger than 0x1000.
    
    2016-09-19  Jose E. Marchesi  <jose.marchesi@oracle.com>
    
    	* elfxx-sparc.c (_bfd_sparc_elf_size_dynamic_sections): Allow
    	negative offsets to _GLOBAL_OFFSET_TABLE_ if the .got section is
    	bigger than 0x1000 bytes.

Diff:
---
 bfd/ChangeLog     |  6 ++++++
 bfd/elfxx-sparc.c | 16 ++++++++--------
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index b54d0c9..36624ee 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2016-09-19  Jose E. Marchesi  <jose.marchesi@oracle.com>
+
+	* elfxx-sparc.c (_bfd_sparc_elf_size_dynamic_sections): Allow
+	negative offsets to _GLOBAL_OFFSET_TABLE_ if the .got section is
+	bigger than 0x1000 bytes.
+
 2016-09-14  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	* elf32-arm.c (elf32_arm_gc_mark_extra_sections): Only mark section
diff --git a/bfd/elfxx-sparc.c b/bfd/elfxx-sparc.c
index 63558c7..30daedf 100644
--- a/bfd/elfxx-sparc.c
+++ b/bfd/elfxx-sparc.c
@@ -2661,19 +2661,19 @@ _bfd_sparc_elf_size_dynamic_sections (bfd *output_bfd,
   /* Allocate .plt and .got entries, and space for local symbols.  */
   htab_traverse (htab->loc_hash_table, allocate_local_dynrelocs, info);
 
-  if (! ABI_64_P (output_bfd)
-      && !htab->is_vxworks
+  if (!htab->is_vxworks
       && elf_hash_table (info)->dynamic_sections_created)
     {
-      /* Make space for the trailing nop in .plt.  */
-      if (htab->elf.splt->size > 0)
-	htab->elf.splt->size += 1 * SPARC_INSN_BYTES;
+      if (! ABI_64_P (output_bfd))
+        {
+          /* Make space for the trailing nop in .plt.  */
+          if (htab->elf.splt->size > 0)
+            htab->elf.splt->size += 1 * SPARC_INSN_BYTES;
+        }
 
       /* If the .got section is more than 0x1000 bytes, we add
 	 0x1000 to the value of _GLOBAL_OFFSET_TABLE_, so that 13
-	 bit relocations have a greater chance of working.
-
-	 FIXME: Make this optimization work for 64-bit too.  */
+	 bit relocations have a greater chance of working.  */
       if (htab->elf.sgot->size >= 0x1000
 	  && elf_hash_table (info)->hgot->root.u.def.value == 0)
 	elf_hash_table (info)->hgot->root.u.def.value = 0x1000;