I don't see any reason this shouldn't be allowed. AFAICT this is only
disabled due to the heuristics used to determine whether it makes sense
to allow the use of an attribute with `#pragma clang attribute`.
This allows libc++ to drop `_LIBCPP_HIDE_FROM_ABI` in a lot of places,
making the library significantly easier to read.
As reported in issue #103477, visibility of instantiated member
functions used to be ignored when calculating visibility of a
specialization.
This patch modifies `getLVForClassMember` to look up for a source
template for an instantiated member, and changes `mergeTemplateLV` to
apply it.
A similar issue was reported in #31462, but it seems that `extern`
declaration with visibility prevents the function from being emitted
as hidden. This behavior seems correct, even though GCC emits it as
with default visibility instead.
Both tests from #103477 and #31462 are added as LIT tests `test72` and
`test73` respectively.
MemberPointerType may refer to a dependent class (qualifier), for
which getMostRecentCXXRecordDecl returns NULL. It seems that the
compiler never executed this code path before patch #136128 where the
issue was reported.
LIT tests 74 and 75 are reduced from Chromium and LLVM libc test
harness as reported in #136128.
Function member (test74):
MemberPointerType 'type-parameter-0-0 (type-parameter-0-1::*)(void)' dependent
|-TemplateTypeParmType 'type-parameter-0-1' dependent depth 0 index 1
`-FunctionProtoType 'type-parameter-0-0 (void)' dependent cdecl
`-TemplateTypeParmType 'type-parameter-0-0' dependent depth 0 index 0
Template parameter (test75):
MemberPointerType 'type-parameter-0-1 type-parameter-0-0::*' dependent
|-TemplateTypeParmType 'type-parameter-0-0' dependent depth 0 index 0
`-TemplateTypeParmType 'type-parameter-0-1' dependent depth 0 index 1
As reported in issue #103477, visibility of instantiated member
functions used to be ignored when calculating visibility of a
specialization.
This patch modifies `getLVForClassMember` to look up for a source
template for an instantiated member, and changes `mergeTemplateLV` to
apply it.
A similar issue was reported in #31462, but it seems that `extern`
declaration with visibility prevents the function from being emitted as
hidden. This behavior seems correct, even though GCC emits it as with
default visibility instead.
Both tests from #103477 and #31462 are added as LIT tests `test72` and
`test73` respectively.
As part of the migration to ptradd
(https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699),
we need to change the representation of the `inrange` attribute, which
is used for vtable splitting.
Currently, inrange is specified as follows:
```
getelementptr inbounds ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, inrange i32 1, i64 2)
```
The `inrange` is placed on a GEP index, and all accesses must be "in
range" of that index. The new representation is as follows:
```
getelementptr inbounds inrange(-16, 16) ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, i32 1, i64 2)
```
This specifies which offsets are "in range" of the GEP result. The new
representation will continue working when canonicalizing to ptradd
representation:
```
getelementptr inbounds inrange(-16, 16) (i8, ptr @vt, i64 48)
```
The inrange offsets are relative to the return value of the GEP. An
alternative design could make them relative to the source pointer
instead. The result-relative format was chosen on the off-chance that we
want to extend support to non-constant GEPs in the future, in which case
this variant is more expressive.
This implementation "upgrades" the old inrange representation in bitcode
by simply dropping it. This is a very niche feature, and I don't think
trying to upgrade it is worthwhile. Let me know if you disagree.
https://reviews.llvm.org/D128482 regressed certain cases of VTT emission
which are no longer hidden with -fvisibility=hidden.
Fix this regression by marking both declarations and definitions.
Fixes [clang codegen][regression] VTT definitions missing
dso_local/hidden/etc markings #72451
We have a new policy in place making links to private resources
something we try to avoid in source and test files. Normally, we'd
organically switch to the new policy rather than make a sweeping change
across a project. However, Clang is in a somewhat special circumstance
currently: recently, I've had several new contributors run into rdar
links around test code which their patch was changing the behavior of.
This turns out to be a surprisingly bad experience, especially for
newer folks, for a handful of reasons: not understanding what the link
is and feeling intimidated by it, wondering whether their changes are
actually breaking something important to a downstream in some way,
having to hunt down strangers not involved with the patch to impose on
them for help, accidental pressure from asking for potentially private
IP to be made public, etc. Because folks run into these links entirely
by chance (through fixing bugs or working on new features), there's not
really a set of problematic links to focus on -- all of the links have
basically the same potential for causing these problems. As a result,
this is an omnibus patch to remove all such links.
This was not a mechanical change; it was done by manually searching for
rdar, radar, radr, and other variants to find all the various
problematic links. From there, I tried to retain or reword the
surrounding comments so that we would lose as little context as
possible. However, because most links were just a plain link with no
supporting context, the majority of the changes are simple removals.
Differential Review: https://reviews.llvm.org/D158071
This reverts commit 809a1e0ffd7af40ee27270ff8ba2ffc927330e71.
Mach-O doesn't support dso_local and this change broke XNU because of the use of dso_local.
Differential Revision: https://reviews.llvm.org/D98458
* static relocation model: always
* other relocation models: if isStrongDefinitionForLinker
This will make LLVM IR emitted for COFF/Mach-O and executable ELF similar.
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
