Richard,
Your proposed patch fails to bootstrap here on
x86_64-apple-darwin14 against the system clang compilers...
g++ -c -g -DIN_GCC -fno-exceptions -fno-rtti
-fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wno-format -Wmissing-format-attribute
-Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros
-Wno-overlength-strings -fno-common -DHAVE_CONFIG_H -I. -I.
-I../../gcc-5-20150211/gcc -I../../gcc-5-20150211/gcc/.
-I../../gcc-5-20150211/gcc/../include
-I../../gcc-5-20150211/gcc/../libcpp/include -I/sw/include
-I/sw/include -I../../gcc-5-20150211/gcc/../libdecnumber
-I../../gcc-5-20150211/gcc/../libdecnumber/dpd -I../libdecnumber
-I../../gcc-5-20150211/gcc/../libbacktrace -I/sw/include -I/sw/include
-o varasm.o -MT varasm.o -MMD -MP -MF ./.deps/varasm.TPo
../../gcc-5-20150211/gcc/varasm.c
...
../../gcc-5-20150211/gcc/varasm.c:6899:9: error: use of undeclared
identifier 'resolution_to_local_definition_p'
return resolution_to_local_definition_p (vnode->resolution);
^
../../gcc-5-20150211/gcc/varasm.c:6906:9: error: use of undeclared
identifier 'resolution_to_local_definition_p'
return resolution_to_local_definition_p (node->resolution);
^
Jack
On Tue, Feb 10, 2015 at 4:19 PM, Richard Henderson <[email protected]> wrote:
> On 02/07/2015 08:45 AM, H.J. Lu wrote:
>> Here is an updated patch.
>
> This is an annoying comment to differentiate 3 different versions, FYI.
>
>> @@ -6826,11 +6817,18 @@ default_binds_local_p_1 (const_tree exp, int shlib)
>> && (TREE_STATIC (exp) || DECL_EXTERNAL (exp)))
>> {
>> varpool_node *vnode = varpool_node::get (exp);
>> - if (vnode && (resolution_local_p (vnode->resolution) ||
>> vnode->in_other_partition))
>> - resolved_locally = true;
>> - if (vnode
>> - && resolution_to_local_definition_p (vnode->resolution))
>> - resolved_to_local_def = true;
>> + /* If not building shared library, common or initialized symbols
>> + are also resolved locally, regardless they are weak or not if
>> + weak_dominate is true. */
>> + if (vnode)
>> + {
>> + if ((weak_dominate && !shlib && vnode->definition)
>> + || vnode->in_other_partition
>> + || resolution_local_p (vnode->resolution))
>> + resolved_locally = true;
>> + if (resolution_to_local_definition_p (vnode->resolution))
>> + resolved_to_local_def = true;
>> + }
>> }
>> else if (TREE_CODE (exp) == FUNCTION_DECL && TREE_PUBLIC (exp))
>> {
>
> Not the same test for a function_decl? That's certainly a mistake.
>
> Indeed, I believe we can now unify these two cases by using the base
> symtab_node instead of varpool_node and cgraph_node.
>
> I'm a bit confused about why we have both resolved_to_local_def vs
> resolved_locally. At least within this function, which only cares about
> module
> locality rather than object file locality. Honza?
>
>> @@ -6859,9 +6857,15 @@ default_binds_local_p_1 (const_tree exp, int shlib)
>> else if (! TREE_PUBLIC (exp))
>> local_p = true;
>> /* A variable is local if the user has said explicitly that it will
>> - be. */
>> + be and it is resolved or defined locally, not compiling for PIC,
>> + not weak or weak_dominate is false. */
>> else if ((DECL_VISIBILITY_SPECIFIED (exp)
>> || resolved_to_local_def)
>> + && (!weak_dominate
>> + || resolved_locally
>> + || !flag_pic
>> + || !DECL_EXTERNAL (exp)
>> + || !DECL_WEAK (exp))
>> && DECL_VISIBILITY (exp) != VISIBILITY_DEFAULT)
>> local_p = true;
>
> I think this test is conflating several issues, and as such it's very
> confusing.
>
> As an existing issue, I'm not sure why "specified" visibility is any different
> from unspecified visibility. As far as I'm aware, the "specified" bit simply
> means that the decl doesn't inherit inherit visibility from the class, or from
> the command-line. But once we're this far, the visibility actually applied to
> the symbol should be all that matters.
>
> Unfortunately, this test is 11 years old, from r85167. It came in as part of
> the implementation of the visibility attribute for the class.
>
> I believe the next test should be
>
> else if (DECL_WEAK (exp) && !resolved_locally)
> local_p = false;
>
> Given the change above, resolved_locally will now be true for (weak && defined
> && weak_dominate), and therefore we need not reiterate that test.
>
> I believe the next test should be dictated by normal non-lto usage like
>
> extern void bar(void) __attribute__((visibility("hidden")));
> void foo(void) { ... bar(); ...)
>
> where the user is expecting that the function call make use of a simpler
> instruction sequence, probably avoiding an PLT. Therefore
>
> else if (DECL_VISIBILITY (exp) != VISIBILITY_DEFAULT)
> local_p = true;
>
> Since we have already excluded undef-weak, we know that any symbol here is
> either defined or strong, and non-default visibility must resolve it locally.
>
>> /* Variables defined outside this object might not be local. */
>> @@ -6881,8 +6885,9 @@ default_binds_local_p_1 (const_tree exp, int shlib)
>> else if (shlib)
>> local_p = false;
>> /* Uninitialized COMMON variable may be unified with symbols
>> - resolved from other modules. */
>> + resolved from other modules unless weak_dominate is true. */
>> else if (DECL_COMMON (exp)
>> + && !weak_dominate
>> && !resolved_locally
>
> Like the weak test, surely weak_dominate has already been accounted for.
>
>> @@ -7445,9 +7465,10 @@ default_elf_asm_output_external (FILE *file
>> ATTRIBUTE_UNUSED,
>> {
>> /* We output the name if and only if TREE_SYMBOL_REFERENCED is
>> set in order to avoid putting out names that are never really
>> - used. */
>> + used. Always output visibility specified in the source. */
>> if (TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))
>> - && targetm.binds_local_p (decl))
>> + && (DECL_VISIBILITY_SPECIFIED (decl)
>> + || targetm.binds_local_p (decl)))
>> maybe_assemble_visibility (decl);
>
> Explain?
>
> I'm testing the following in the meantime, in order to validate my hypotheses
> above.
>
>
> r~
>
