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 --git a/gold/ChangeLog b/gold/ChangeLog
index 946504a..2944b51 100644 (file)
--- 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 (file)
--- 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);
 }