http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47952
Aldy Hernandez <aldyh at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #3 from Aldy Hernandez <aldyh at gcc dot gnu.org> 2011-03-07
15:37:06 UTC ---
[These notes are from a question via email to Jakub/Richard. Saving here to
keep everything in one place. Still awaiting response.]
In this PR we have an undefined reference to symbol
"_ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC1EPSt15_List_node_base" (see
full .s in attachment). This symbol is only used in the .tm_clone_table:
.section .tm_clone_table,"aw",@progbits
[...]
.quad _ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC1EPSt15_List_node_base
[...]
However, the symbol seems to be an alias to another symbol (which is used):
.globl _ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC1EPSt15_List_node_base
.set
_ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC1EPSt15_List_node_base,
_ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC2EPSt15_List_node_base
Notice these are constructor variants (C1 versus C2 in the mangling).
The original symbol is defined like this:
.section
.text._ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC2EPSt15_List_node_base,"axG",@progbits,_ZNSt14_List_iteratorIN4Game12BuildProjectEEC5EPSt15_List_node_base,comdat
.align 2
.weak
_ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC2EPSt15_List_node_base
.type
_ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC2EPSt15_List_node_base,
@function
_ZGTtNSt14_List_iteratorIN4Game12BuildProjectEEC2EPSt15_List_node_base:
[...]
[...]
This is a wild guess, but should we avoid dumping symbols in the
.tm_clone_table if the original function was a weak symbol? The one-liner
below, fixes the undefined reference at hand, as well as a myriad of other
linking problems in the Glob2 benchmark.
??
Index: varasm.c
===================================================================
--- varasm.c (revision 170622)
+++ varasm.c (working copy)
@@ -5867,6 +5867,9 @@ finish_tm_clone_pairs_1 (void **slot, vo
if (!src_n->needed)
return 1;
+ if (DECL_WEAK (src_n->decl))
+ return 1;
+
if (!*switched)
{
switch_to_section (get_named_section (NULL, ".tm_clone_table", 3));
