If control falls off the end of a function after an __asm block, MSVC
assumes that the inline assembly filled the EAX and possibly EDX
registers with an appropriate return value. This functionality is used
in inline functions returning 64-bit integers in system headers, so we
need some amount of compatibility.
This is implemented in Clang by adding extra output constraints to every
inline asm block, and storing the resulting output registers into the
return value slot. If we see an asm block somewhere in the function
body, we emit a normal epilogue instead of marking the end of the
function with a return type unreachable.
Normal returns in functions not using this functionality will overwrite
the return value slot, and in most cases LLVM should be able to
eliminate the dead stores.
Fixes PR17201.
Reviewed By: majnemer
Differential Revision: http://reviews.llvm.org/D5177
llvm-svn: 217187
This avoids encoding information about the function prototype into the
thunk at the cost of some function prototype bitcast gymnastics.
Fixes PR20653.
llvm-svn: 216782
In C++11, instantiation of exception specs is deferred. The instantiation is
done in MarkFunctionReferenced(), which wasn't called for non-OdrUsed functions,
which then caused an assert in codegen. Fixes PR19190, see the bug for details.
llvm-svn: 216562
We would previously assert (a decl cannot have two DLL attributes) on this code:
template <typename T> struct __declspec(dllimport) S { T f() { return T(); } };
template struct __declspec(dllexport) S<int>;
The problem was that when instantiating, we would take the attribute from the
template even if the instantiation itself already had an attribute.
Also, don't inherit DLL attributes from the template to its members before
instantiation, as the attribute may change.
I couldn't figure out what MinGW does here, so I'm leaving that open. At least
we're not asserting anymore.
llvm-svn: 216340
This already works, but somewhat by accident (due to the order of
emission in clang, the location is set to the loop header (during the
emission of the iteratior increment) before the loop backedge is
emitted), so let's just add a test for symmetry and future-proofing.
llvm-svn: 216298
Similar to r215768 (which fixed the same case for while loops). To quote
r215768's commit message:
"A little test case simplification - this could be simplified further,
though there are certainly interesting connections to the if/else
construct so I'm hesitant to remove that entirely though it does appear
somewhat unrelated.
(similar fix to r215766, related to PR19864)"
llvm-svn: 216297
for loops introduce two scopes - one for the outer loop variable and its
initialization, and another for the body of the loop, including any
variable declared inside the loop condition.
llvm-svn: 216288
The Itanium ABI will give out the same mangling number for two different
lambdas if their call operators have different types. The MS ABI cannot
do the same because it does not mangle the return type into it's
lambdas.
This fixes PR20719.
llvm-svn: 216259
Normally we mark all members of exported classes referenced to get them emitted.
However, MSVC doesn't do this for class templates that are implicitly specialized or
just have an explicit instantiation declaration. For such specializations, the members
are emitted when referenced.
The exception is the case when the dllexport attribute is propagated from a base class
to a base class template that doesn't have an explicit attribute: in this case all
methods of the base class template do get instantiated.
llvm-svn: 216145
MSVC "14" CTP 3 has fixed it's mangling for alias templates when used as
template-template arguments; update clang to be compatible with this
mangling.
llvm-svn: 215972
This fixes PR20671, see the bug for details. In short, ActOnTranslationUnit()
calls DefineUsedVTables() and only then PerformPendingInstantiations(). But
PerformPendingInstantiations() is what does delayed template parsing, so
vtables only references from late-parsed templates weren't marked used.
As a fix, move the SavePendingInstantiationsAndVTableUsesRAII in
PerformPendingInstantiations() up above the delayed template parsing code.
That way, vtables referenced from templates end up in the RAII object, and the
call to DefineUsedVTables() in PerformPendingInstantiations() marks them used.
llvm-svn: 215786
A little test case simplification - this could be simplified further,
though there are certainly interesting connections to the if/else
construct so I'm hesitant to remove that entirely though it does appear
somewhat unrelated.
(similar fix to r215766, related to PR19864)
llvm-svn: 215768
This avoids debuggers stepping to strange places (like the last
statement in the loop body, or the first statement in the if).
This is not the whole answer, though - similar bugs no doubt exist in
other loops (patches to follow) and attributing exception handling code
to the correct line is also tricky (based on the previous fix to
PR19864, exception handling is still erroneously attributed to the 'if'
line).
llvm-svn: 215766
C++11 allows this qualifiers to exist on function types when used in
template arguments. Previously, I believed it wasn't possible because
MSVC rejected declarations like: S<int () const &> s;
However, it turns out MSVC properly allows them in using declarations;
updated clang to be compatible with this mangling.
llvm-svn: 215464
Previously, assigning an inheritance model to a derived class would
trigger further assiginments to the various bases of the class. This
was done to fix a bug where we couldn't handle an implicit
base-to-derived conversion for pointers-to-members when the conversion
was ambiguous at an earlier point.
However, this is not how the MS scheme works. Instead, assign
inheritance models to *just* the class which owns to declaration we
ended up referencing.
N.B. This result is surprising in many ways. It means that it is
possible for a base to have a "larger" inheritance model than it's
derived classes. It also means that bases in the conversion path do not
get assigned a model.
struct A { void f(); void f(int); };
struct B : A {};
struct C : B {};
void f() { void (C::*x)() = &A::f; }
We can only begin to assign an inheritance model *after* we've seen the
address-of but *before* we've done the implicit conversion the more
derived pointer-to-member type. After that point, both 'A' and 'C' will
have an inheritance model but 'B' will not. Surprising, right?
llvm-svn: 215174
There are no vtable offset offsets in the MS ABI, but vbtable offsets
are analogous. There are no consumers of this information yet, but at
least we don't crash now.
llvm-svn: 215149
This reverts commit r215137.
This doesn't work at all, an offset-offset is probably different than an
offset. I'm scared that this passed our normal test suite.
llvm-svn: 215141
It is possible for lambdas to get the same mangling number because they
may exist in different mangling contexts. To handle this correctly,
mangle the context into the name as well.
llvm-svn: 214947
The MS mangling scheme apparently has separate manglings for type and
non-type parameter packs when they are empty. Match template arguments
with parameters during mangling; check the parameter to see if it was
destined to hold type-ish things or nontype-ish things.
Differential Revision: http://reviews.llvm.org/D4792
llvm-svn: 214932
to instruct the code generator to not enforce a higher alignment
than the given number (of bytes) when accessing memory via an opaque
pointer or reference. Patch reviewed by John McCall (with post-commit
review pending). rdar://16254558
llvm-svn: 214911
This matches MSVC's logic, which seems to be that when the friend
declaration is qualified, it cannot be a declaration of a new symbol
and so the dll linkage doesn't change.
Differential Revision: http://reviews.llvm.org/D4764
llvm-svn: 214774
or a class derived from T. We already supported this when initializing
_Atomic(T) from T for most (and maybe all) other reasonable values of T.
llvm-svn: 214390
A templated using declaration may be used as a template-template
argument.
Unfortunately, the VS "14" chooses '?' as the sole marker for the
argument. This is problematic because it presupposes the possibility of
using more than one template-aliases as arguments to the same template.
This fixes PR20047.
llvm-svn: 214290
Reid Kleckner