> On 02/11/2014 07:54 PM, Jan Hubicka wrote:
> >+ /* Allow combining RTTI and non-RTTI is OK. */
>
> You mean combining -frtti and -fno-rtti compiles? Yes, that's fine,
> though you need to prefer the -frtti version in case code from that
> translation unit uses the RTTI info.
Is there some mechanism that linker will do so? At the moment we just chose
variant
that would be selected by linker. I can make the choice, but what happens with
non-LTO?
>
> >/aux/hubicka/firefox/accessible/src/generic/DocAccessible.cpp:1232:0: note:
> >the first different method is �HandleAccEvent�
>
> I don't see where this note would come from in the patch.
>
Sorry, diffed old tree
Index: ipa-devirt.c
===================================================================
--- ipa-devirt.c (revision 207702)
+++ ipa-devirt.c (working copy)
@@ -1675,6 +1675,132 @@
}
+/* Compare two virtual tables, PREVAILING and VTABLE and output ODR
+ violation warings. */
+
+void
+compare_virtual_tables (tree prevailing, tree vtable)
+{
+ tree init1 = DECL_INITIAL (prevailing), init2 = DECL_INITIAL (vtable);
+ tree val1 = NULL, val2 = NULL;
+ if (!DECL_VIRTUAL_P (prevailing))
+ {
+ odr_violation_reported = true;
+ if (warning_at (DECL_SOURCE_LOCATION (prevailing), 0,
+ "declaration %D conflict with a virtual table",
+ prevailing))
+ inform (DECL_SOURCE_LOCATION (TYPE_NAME (DECL_CONTEXT (vtable))),
+ "a type defining the virtual table in another translation
unit");
+ return;
+ }
+ if (init1 == init2 || init2 == error_mark_node)
+ return;
+ /* Be sure to keep virtual table contents even for external
+ vtables when they are available. */
+ gcc_assert (init1 && init1 != error_mark_node);
+ if (!init2 && DECL_EXTERNAL (vtable))
+ return;
+ if (init1 && init2
+ && CONSTRUCTOR_NELTS (init1) == CONSTRUCTOR_NELTS (init2))
+ {
+ unsigned i;
+ tree field1, field2;
+ bool matched = true;
+
+ FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (init1),
+ i, field1, val1)
+ {
+ gcc_assert (!field1);
+ field2 = CONSTRUCTOR_ELT (init2, i)->index;
+ val2 = CONSTRUCTOR_ELT (init2, i)->value;
+ gcc_assert (!field2);
+ if (val2 == val1)
+ continue;
+ if (TREE_CODE (val1) == NOP_EXPR)
+ val1 = TREE_OPERAND (val1, 0);
+ if (TREE_CODE (val2) == NOP_EXPR)
+ val2 = TREE_OPERAND (val2, 0);
+ /* Unwind
+ val <addr_expr type <pointer_type>
+ readonly constant
+ arg 0 <mem_ref type <pointer_type __vtbl_ptr_type>
+ readonly
+ arg 0 <addr_expr type <pointer_type>
+ arg 0 <var_decl _ZTCSd0_Si>> arg 1 <integer_cst 24>>> */
+
+ while (TREE_CODE (val1) == TREE_CODE (val2)
+ && (((TREE_CODE (val1) == MEM_REF
+ || TREE_CODE (val1) == POINTER_PLUS_EXPR)
+ && (TREE_OPERAND (val1, 1))
+ == TREE_OPERAND (val2, 1))
+ || TREE_CODE (val1) == ADDR_EXPR))
+ {
+ val1 = TREE_OPERAND (val1, 0);
+ val2 = TREE_OPERAND (val2, 0);
+ if (TREE_CODE (val1) == NOP_EXPR)
+ val1 = TREE_OPERAND (val1, 0);
+ if (TREE_CODE (val2) == NOP_EXPR)
+ val2 = TREE_OPERAND (val2, 0);
+ }
+ if (val1 == val2)
+ continue;
+ if (TREE_CODE (val2) == ADDR_EXPR)
+ {
+ tree tmp = val1;
+ val1 = val2;
+ val2 = tmp;
+ }
+ /* Combining RTTI and non-RTTI vtables is OK.
+ ??? Perhaps we can alsa (optionally) warn here? */
+ if (TREE_CODE (val1) == ADDR_EXPR
+ && TREE_CODE (TREE_OPERAND (val1, 0)) == VAR_DECL
+ && !DECL_VIRTUAL_P (TREE_OPERAND (val1, 0))
+ && integer_zerop (val2))
+ continue;
+ /* For some reason zeros gets NOP_EXPR wrappers. */
+ if (integer_zerop (val1)
+ && integer_zerop (val2))
+ continue;
+ /* Compare assembler names; this function is run during
+ declaration merging. */
+ if (DECL_P (val1) && DECL_P (val2)
+ && DECL_ASSEMBLER_NAME (val1) == DECL_ASSEMBLER_NAME (val2))
+ continue;
+ matched = false;
+ break;
+ }
+ if (!matched)
+ {
+ odr_violation_reported = true;
+ if (warning_at (DECL_SOURCE_LOCATION (TYPE_NAME (DECL_CONTEXT
(vtable))), 0,
+ "type %qD violates one definition rule",
+ DECL_CONTEXT (vtable)))
+ {
+ inform (DECL_SOURCE_LOCATION (TYPE_NAME (DECL_CONTEXT
(prevailing))),
+ "a type with the same name but different virtual table is
"
+ "defined in another translation unit");
+ /* See if we can be more informative. */
+ if (val1 && val2 && TREE_CODE (val1) == FUNCTION_DECL
+ && TREE_CODE (val1) == FUNCTION_DECL
+ && !DECL_ARTIFICIAL (val1) && !DECL_ARTIFICIAL (val2))
+ {
+ inform (DECL_SOURCE_LOCATION (val1),
+ "the first different method is %qD", val1);
+ inform (DECL_SOURCE_LOCATION (val2),
+ "a conflicting method is %qD", val2);
+ }
+ }
+ }
+ return;
+ }
+ if (warning_at (DECL_SOURCE_LOCATION (TYPE_NAME (DECL_CONTEXT (vtable))), 0,
+ "type %qD violates one definition rule",
+ DECL_CONTEXT (vtable)))
+ inform (DECL_SOURCE_LOCATION (TYPE_NAME (DECL_CONTEXT (prevailing))),
+ "a type with the same name but number of virtual methods is "
+ "defined in another translation unit");
+}
+
/* Return true if N looks like likely target of a polymorphic call.
Rule out cxa_pure_virtual, noreturns, function declared cold and
other obvious cases. */
Index: lto/lto-symtab.c
===================================================================
--- lto/lto-symtab.c (revision 207701)
+++ lto/lto-symtab.c (working copy)
@@ -679,5 +679,14 @@
if (!ret)
return decl;
+ /* Check and report ODR violations on virtual tables. */
+ if (decl != ret->decl
+ && TREE_CODE (decl) == VAR_DECL && DECL_VIRTUAL_P (decl))
+ {
+ compare_virtual_tables (ret->decl, decl);
+ /* We are done with checking and DECL will die after merigng. */
+ DECL_VIRTUAL_P (decl) = 0;
+ }
+
return ret->decl;
}
Index: ipa-utils.h
===================================================================
--- ipa-utils.h (revision 207702)
+++ ipa-utils.h (working copy)
@@ -92,6 +92,7 @@
tree, tree, HOST_WIDE_INT);
tree vtable_pointer_value_to_binfo (tree t);
bool vtable_pointer_value_to_vtable (tree, tree *, unsigned HOST_WIDE_INT *);
+void compare_virtual_tables (tree, tree);
/* Return vector containing possible targets of polymorphic call E.
If FINALP is non-NULL, store true if the list is complette.
