[binutils-gdb] Allow undefined references to TLS symbols.

[Cary Coutant]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=65d9213705654383804ab8af707975f0721c4a6d

commit 65d9213705654383804ab8af707975f0721c4a6d
Author: Cary Coutant <ccoutant@google.com>
Date:   Wed Jan 28 15:39:08 2015 -0800

    Allow undefined references to TLS symbols.
    
    When --warn-unresolved-symbols is used, gold tries to create a dynamic relocation
    for it, and gives an internal error if the TLS segment has not already been
    created. This patch allows the IE-to-LE optimization for an undefined symbol
    when building an executable, which suppresses the dynamic relocation, and
    relaxes the requirement to have a TLS segment when applying a relocation for
    an undefined symbol.
    
    2015-01-28  Cary Coutant  <ccoutant@google.com>
    
    gold/
    	* x86_64.cc (Target_x86_64::Scan::global): Allow IE-to-LE optimization
    	for undef TLS symbols.
    	(Target_x86_64::Relocate::relocate_tls): Likewise.
    	(Target_x86_64::Relocate::tls_ie_to_le): Likewise.

Diff:
---
 gold/ChangeLog |  7 +++++++
 gold/x86_64.cc | 20 +++++++++++++++++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/gold/ChangeLog b/gold/ChangeLog
index 946504a..2944b51 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,10 @@
+2015-01-28  Cary Coutant  <ccoutant@google.com>
+
+	* x86_64.cc (Target_x86_64::Scan::global): Allow IE-to-LE optimization
+	for undef TLS symbols.
+	(Target_x86_64::Relocate::relocate_tls): Likewise.
+	(Target_x86_64::Relocate::tls_ie_to_le): Likewise.
+
 2015-01-25  Cary Coutant  <ccoutant@google.com>
 
 	* output.cc (Output_segment::set_section_addresses): Fix calculation
diff --git a/gold/x86_64.cc b/gold/x86_64.cc
index dd6c07b..a4aebc8 100644
--- a/gold/x86_64.cc
+++ b/gold/x86_64.cc
@@ -2983,7 +2983,12 @@ Target_x86_64<size>::Scan::global(Symbol_table* symtab,
     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
       {
-	const bool is_final = gsym->final_value_is_known();
+	// For the Initial-Exec model, we can treat undef symbols as final
+	// when building an executable.
+	const bool is_final = (gsym->final_value_is_known() ||
+			       (r_type == elfcpp::R_X86_64_GOTTPOFF &&
+			        gsym->is_undefined() &&
+				parameters->options().output_is_executable()));
 	const tls::Tls_optimization optimized_type
 	    = Target_x86_64<size>::optimize_tls_reloc(is_final, r_type);
 	switch (r_type)
@@ -3779,7 +3784,15 @@ Target_x86_64<size>::Relocate::relocate_tls(
       break;
 
     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
-      if (optimized_type == tls::TLSOPT_TO_LE)
+      if (gsym != NULL && gsym->is_undefined())
+	{
+	  Target_x86_64<size>::Relocate::tls_ie_to_le(relinfo, relnum,
+						      NULL, rela,
+						      r_type, value, view,
+						      view_size);
+	  break;
+	}
+      else if (optimized_type == tls::TLSOPT_TO_LE)
 	{
 	  if (tls_segment == NULL)
 	    {
@@ -4126,7 +4139,8 @@ Target_x86_64<size>::Relocate::tls_ie_to_le(
       view[-1] = 0x80 | reg | (reg << 3);
     }
 
-  value -= tls_segment->memsz();
+  if (tls_segment != NULL)
+    value -= tls_segment->memsz();
   Relocate_functions<size, false>::rela32(view, value, 0);
 }