http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53476
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> 2012-12-13
13:49:47 UTC ---
Reduced testcase:
static int Wv10a __attribute__((weakref ("Wv10b")));
static int Wv10b __attribute__((weakref ("wv10")));
extern int wv10;
extern void abort (void);
int main ()
{
if (!!&Wv10a)
abort ();
return 0;
}
fails to link at -O1 works with -O0.
>From .000i.cgraph:
Reclaiming functions:
Reclaiming variables:
Clearing address taken flags:
Trivially needed variables:
Removing variables: Wv10a
Final Symbol table:
...
Breakpoint 5, varpool_remove_unreferenced_decls ()
at /space/rguenther/src/svn/trunk/gcc/varpool.c:405
405 varpool_remove_node (node);
(gdb) call debug_symtab_node((symtab_node)node)
Wv10a/0 (Wv10a) @0x7ffff68fa068
Type: variable
Visibility: external weak
References: Wv10b/1 (alias)
Referring: main/2 (addr)
Availability: available
Varpool flags: analyzed finalized
so it's still refered to.
if (cgraph_dump_file)
fprintf (cgraph_dump_file, "Trivially needed variables:");
FOR_EACH_DEFINED_VARIABLE (node)
{
if (node->analyzed
&& (!varpool_can_remove_if_no_refs (node)
/* We just expanded all function bodies. See if any of
them needed the variable. */
|| (!DECL_EXTERNAL (node->symbol.decl)
&& DECL_RTL_SET_P (node->symbol.decl))))
doesn't catch it because
(gdb) call debug_tree (node->symbol.decl)
<var_decl 0x7ffff68045f0 Wv10a
type <integer_type 0x7ffff67f75e8 int public SI
size <integer_cst 0x7ffff67fa0c0 constant 32>
unit size <integer_cst 0x7ffff67fa0e0 constant 4>
align 32 symtab 0 alias set -1 canonical type 0x7ffff67f75e8 precision
32 min <integer_cst 0x7ffff67fa060 -2147483648> max <integer_cst 0x7ffff67fa080
2147483647>
pointer_to_this <pointer_type 0x7ffff67ff2a0>>
addressable used static external weak SI file t.c line 1 col 12 size
<integer_cst 0x7ffff67fa0c0 32> unit size <integer_cst 0x7ffff67fa0e0 4>
align 32 context <translation_unit_decl 0x7ffff6918000 D.1721> attributes
<tree_list 0x7ffff68f3c08>
(mem:SI (symbol_ref/i:DI ("Wv10a") <var_decl 0x7ffff68045f0 Wv10a>) [0
Wv10a+0 S4 A32]) chain <var_decl 0x7ffff6804688 Wv10b>>
it has DECL_EXTERNAL set (but it also is TREE_STATIC and has RTL!).
On the 4.7 branch we simply checked whether the DECL had RTL but didn't bother
to check whether it does not have DECL_EXTERNAL set.
I'd say either revert to 4.7 behavior here or do
Index: varpool.c
===================================================================
--- varpool.c (revision 194472)
+++ varpool.c (working copy)
@@ -358,7 +358,8 @@ varpool_remove_unreferenced_decls (void)
&& (!varpool_can_remove_if_no_refs (node)
/* We just expanded all function bodies. See if any of
them needed the variable. */
- || (!DECL_EXTERNAL (node->symbol.decl)
+ || (!(DECL_EXTERNAL (node->symbol.decl)
+ && !TREE_STATIC (node->symbol.decl))
&& DECL_RTL_SET_P (node->symbol.decl))))
{
enqueue_node (node, &first);
testing reversal to 4.7 behavior.
