From cd04836359da82ae1dc67e5a05565536f4427b51 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Mon, 5 Feb 2018 08:38:16 -0800
Subject: x86: Remove the unused _GLOBAL_OFFSET_TABLE_

Since _GLOBAL_OFFSET_TABLE_ may be referenced implicitly on x86,
checking ref_regular_nonweak leaves the unused _GLOBAL_OFFSET_TABLE_
in output.  This patch checks explicit GOT references instead.

ld-i386/discarded1.s and ld-x86-64/discarded1.s are updated to avoid
linker optimization which removes GOT references.

bfd/

	PR ld/22782
	* elf32-i386.c (elf_i386_check_relocs): Set got_referenced if
	_GLOBAL_OFFSET_TABLE_ is referenced or GOT is needed to resolve
	undefined weak symbol to 0.
	* elf64-x86-64.c (elf_x86_64_check_relocs): Set got_referenced
	if _GLOBAL_OFFSET_TABLE_ is referenced.
	* elfxx-x86.c (_bfd_x86_elf_size_dynamic_sections): Check
	got_referenced instead of ref_regular_nonweak.  Remove the
	unused _GLOBAL_OFFSET_TABLE_ from symbol table.
	* elfxx-x86.h (elf_x86_link_hash_table): Add got_referenced.

ld/

	PR ld/22782
	* testsuite/ld-i386/discarded1.s: Replace mov with div.
	* testsuite/ld-x86-64/discarded1.s: Likewise.
	* testsuite/ld-i386/i386.exp: Run pr22782.
	* testsuite/ld-i386/load1-nacl.d: Updated for removing
	_GLOBAL_OFFSET_TABLE_ from output.
	* testsuite/ld-i386/load1.d: Likewise.
	* testsuite/ld-x86-64/load1a-nacl.d: Likewise.
	* testsuite/ld-x86-64/load1a.d: Likewise.
	* testsuite/ld-x86-64/load1b-nacl.d: Likewise.
	* testsuite/ld-x86-64/load1b.d: Likewise.
	* testsuite/ld-i386/pr22782.d: New file.
	* testsuite/ld-i386/pr22782.s: Likewise.
	* testsuite/ld-x86-64/pr22782.s: Likewise.
	* testsuite/ld-x86-64/pr22782a.d: Likewise.
	* testsuite/ld-x86-64/pr22782b.d: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run pr22782a and pr22782b.
---
 bfd/elfxx-x86.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

(limited to 'bfd/elfxx-x86.c')

diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index a7db5d9..dbda542 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -1086,7 +1086,7 @@ _bfd_x86_elf_size_dynamic_sections (bfd *output_bfd,
       /* Don't allocate .got.plt section if there are no GOT nor PLT
 	 entries and there is no reference to _GLOBAL_OFFSET_TABLE_.  */
       if ((htab->elf.hgot == NULL
-	   || !htab->elf.hgot->ref_regular_nonweak)
+	   || !htab->got_referenced)
 	  && (htab->elf.sgotplt->size == bed->got_header_size)
 	  && (htab->elf.splt == NULL
 	      || htab->elf.splt->size == 0)
@@ -1096,7 +1096,20 @@ _bfd_x86_elf_size_dynamic_sections (bfd *output_bfd,
 	      || htab->elf.iplt->size == 0)
 	  && (htab->elf.igotplt == NULL
 	      || htab->elf.igotplt->size == 0))
-	htab->elf.sgotplt->size = 0;
+	{
+	  htab->elf.sgotplt->size = 0;
+	  if (htab->elf.hgot != NULL)
+	    {
+	      /* Remove the unused _GLOBAL_OFFSET_TABLE_ from symbol
+		 table. */
+	      htab->elf.hgot->root.type = bfd_link_hash_undefined;
+	      htab->elf.hgot->root.u.undef.abfd
+		= htab->elf.hgot->root.u.def.section->owner;
+	      htab->elf.hgot->root.linker_def = 0;
+	      htab->elf.hgot->ref_regular = 0;
+	      htab->elf.hgot->def_regular = 0;
+	    }
+	}
     }
 
   if (_bfd_elf_eh_frame_present (info))
-- 
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