Re: [RFC][PATCH] Check ELF relocs after opening all all input files

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Apr 19, 2016 at 4:47 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> Now, if you run check_relocs even later, say at
>> ldemul_before_allocation, after gc-sections has run, then all the
>> reference counting code for plt and got relocs can be removed too.
>>
>
> That is on my to-do list.  One step at a time :-).   We can start
> with x86 and enable it for other after we have worked out all the issues
>

Here is the first step.  OK for master?


-- 
H.J.

From 9b5c177dd8957627b028c0bb52d09fef3155a093 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 20 Apr 2016 05:23:45 -0700
Subject: [PATCH] Move ELF relocation check after lang_gc_sections

Move ELF relocation check after lang_gc_sections so that all the
reference counting code for plt and got relocs can be removed.  This
only affects ELF targets which check relocations after opening all
input file.

	* ldlang.c (lang_check_relocs): New function.
	(lang_process): Call lang_check_relocs after lang_gc_sections.
	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Don't
	call _bfd_elf_link_check_relocs here.
---
 ld/emultempl/elf32.em | 14 --------------
 ld/ldlang.c           | 24 ++++++++++++++++++++++++
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index 312f935..4f5d1a4 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -1026,20 +1026,6 @@ gld${EMULATION_NAME}_after_open (void)
   if (!is_elf_hash_table (htab))
     return;
 
-  if (link_info.check_relocs_after_open_input)
-    {
-      bfd *abfd;
-
-      for (abfd = link_info.input_bfds;
-	   abfd != (bfd *) NULL; abfd = abfd->link.next)
-	if (!_bfd_elf_link_check_relocs (abfd, &link_info))
-	  {
-	    /* no object output, fail return */
-	    config.make_executable = FALSE;
-	    return;
-	  }
-    }
-
   if (emit_note_gnu_build_id != NULL)
     {
       bfd *abfd;
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 856e3e2..2ae3640 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -6778,6 +6778,27 @@ lang_add_gc_name (const char * name)
   link_info.gc_sym_list = sym;
 }
 
+/* Check relocations.  */
+
+static void
+lang_check_relocs (void)
+{
+  if (link_info.check_relocs_after_open_input
+      && bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour)
+    {
+      bfd *abfd;
+
+      for (abfd = link_info.input_bfds;
+	   abfd != (bfd *) NULL; abfd = abfd->link.next)
+	if (!_bfd_elf_link_check_relocs (abfd, &link_info))
+	  {
+	    /* no object output, fail return */
+	    config.make_executable = FALSE;
+	    break;
+	  }
+    }
+}
+
 void
 lang_process (void)
 {
@@ -6917,6 +6938,9 @@ lang_process (void)
   /* Remove unreferenced sections if asked to.  */
   lang_gc_sections ();
 
+  /* Check relocations.  */
+  lang_check_relocs ();
+
   /* Update wild statements.  */
   update_wild_statements (statement_list.head);
 
-- 
2.5.5