The ELF symbol visibilities are:
- internal: Not visibile across DSOs, cannot pass address across DSOs
- hidden: Not visibile across DSOs, can be called indirectly
- default: Usually visible across DSOs, possibly interposable
- protected: Visible across DSOs, not interposable
LLVM only supports the latter 3 visibilities. Internal visibility is in
theory useful, as it allows you to assume that the caller is maintaining
a PIC register for you in %ebx, or in some other pre-arranged location.
As far as LLVM is concerned, this isn't worth the trouble. Using hidden
visibility is always correct, so we can just do that.
Resolves PR9183.
llvm-svn: 250954
We attempted to be compatible with GCC's buggy mangling for templates
with a declaration for a template argument.
However, we weren't completely successful in copying their bug in cases
like:
char foo;
template <char &C> decltype(C) f() { return foo; };
template char &f<foo>();
Instead, just follow the ABI specification. This fixes PR22621.
llvm-svn: 229644
Currently we emit DeferredDeclsToEmit in reverse order. This patch changes that.
The advantages of the change are that
* The output order is a bit closer to the source order. The change to
test/CodeGenCXX/pod-member-memcpys.cpp is a good example.
* If we decide to deffer more, it will not cause as large changes in the
estcases as it would without this patch.
llvm-svn: 226751
Clang outputs LLVM one top level decl at a time. This combined with the
visibility computation code looking for the newest NamespaceDecl would cause
it to produce different results for nested namespaces.
The two options for producing consistent results are
* Delay codegen of anything inside a namespace until the end of the file.
* Don't look for the newest NamespaceDecl.
This patch implements the second option.
This matches the gcc behavior too.
llvm-svn: 196712
Since r175326 an implicitly hidden template argument can cause a template
installation to become hidden, even if the template itself has an explicit
default visibility. This requires that we keep track of "late" additions
of the visibility attribute.
This is hopefully the last followup change. It just removes the caching of
visibilities from types so that we can see new attributes even after a type has
been used.
llvm-svn: 176164
Now that implicitly hidden template arguments can make an instantiation hidden,
it is important to look at more than just the canonical decl of the argument
in order to see if an attribute is available in a more recent decl.
This has the disadvantage of exposing when getExplicitVisibility is called,
but lets us handle cases like
template <typename T>
struct __attribute__((visibility("default"))) barT {
static void zed() {}
};
class foo;
class __attribute__((visibility("default"))) foo;
template struct barT<foo>;
llvm-svn: 176112
control the visibility of a type for the purposes of RTTI
and template argument restrictions independently of how
visibility propagates to its non-type member declarations.
Also fix r175326 to not ignore template argument visibility
on a template explicit instantiation when a member has
an explicit attribute but the instantiation does not.
The type_visibility work is rdar://11880378
llvm-svn: 175587
for distinguishing type vs. value visibility.
The changes to the visibility of explicit specializations
are intentional. The change to the "ugly" test case is
a consequence of a sensible implementation, and I am happy
to argue that this is better behavior. Other changes may
or may not be intended; it is quite difficult to divine
intent from some of the code I altered.
I've left behind a comment which I hope explains the
philosophy behind visibility computation.
llvm-svn: 175326
The testcase in pr14929 shows that this is extremely hard to do. If we choose
to apply the attribute, that causes the visibility of some decls to change and
that can happen really late (during codegen).
Current gcc warns and ignores the attribute in this testcase with a warning.
This suggest that the correct solution is to find a point in the compilation
where we can compute the visibility and
* assert it was never computed before
* reject any attempts to compute it again in the future (with warnings).
llvm-svn: 172305
only using the linkage.
Use and test both, documenting that considering the visibility and linkage
of template parameters is a difference from gcc.
llvm-svn: 158309
struct HIDDEN foo {
};
template <class P>
struct bar {
};
template <>
struct HIDDEN bar<foo> {
DEFAULT static void zed();
};
void bar<foo>::zed() {
}
Before we would produce a hidden symbol in
struct HIDDEN foo {
};
template <class P>
struct bar {
};
template <>
struct bar<foo> {
DEFAULT static void zed();
};
void bar<foo>::zed() {
}
But adding HIDDEN to the specialization would cause us to produce a default
symbol.
llvm-svn: 157206
* Don't copy the visibility attribute during instantiations. We have to be able
to distinguish
struct HIDDEN foo {};
template<class T>
DEFAULT void bar() {}
template DEFAULT void bar<foo>();
from
struct HIDDEN foo {};
template<class T>
DEFAULT void bar() {}
template void bar<foo>();
* If an instantiation has an attribute, it takes precedence over an attribute
in the template.
* With instantiation attributes handled with the above logic, we can now
select the minimum visibility when looking at template arguments.
llvm-svn: 156821
the tempale arguments in deciding the visibility.
This agrees with gcc 4.7.
Found by trying to build chrome with component=shared_library with 155314
reverted.
llvm-svn: 155316
This fixes the included testcase and lets us simplify the code a bit. It
does require using mergeWithMin when merging class information to its
members. Expand the comments to explain why that works.
llvm-svn: 155103
an explicit default one. This means that with -fvisibility hidden we
now produce a hidden symbol for
template <typename T>
class DEFAULT foo {
void bar() {}
};
class zed {};
template class foo<zed>;
This matches the behaviour of gcc 4.7.
llvm-svn: 155102
* Handle some situations where we should never make a decl more visible,
even when merging in an explicit visibility.
* Handle attributes in members of classes that are explicitly specialized.
Thanks Nico for the report and testing, Eric for the initial review, and dgregor
for the awesome test27 :-)
llvm-svn: 151236
With that, centralize the way we merge visibility, always preferring explicit over
implicit and then picking the most restrictive one.
Fixes pr10113 and pr11690.
llvm-svn: 148163
Reid Kleckner