The MSVC 2015 ABI utilizes a rather straightforward adaptation of the
algorithm found in the appendix of N2382. While we are here, implement
support for emitting cleanups if an exception is thrown while we are
intitializing a static local variable.
llvm-svn: 236697
These extra endcatch markers aren't helping identify regions to outline,
so let's get rid of them. LLVM outlines (more or less) from begincatch
to endcatch. Any unwind edge from an enclosed invoke is a transition to
a new exception handler, which has it's own outlining markers.
llvm-svn: 235562
The catch object parameter to llvm.eh.begincatch is optional, and can be
null. We can save some ourselves the stack space, copy ctor, and dtor
calls if we pass null.
llvm-svn: 234264
Don't assume that all pointers are convertible to void pointer.
Instead correctly respect [conv.ptr]p2; only allow pointer types with an
object pointee type to be caught as pointer-to-void.
llvm-svn: 234090
Now the GEP constant utility functions require the type to be explicitly
passed (since eventually the pointer type will be opaque and not convey
the required type information). For now callers can still pass nullptr
(though none were needed here in Clang, which is nice) if
convenienc/necessary, but eventually that will be disallowed as well.
llvm-svn: 233937
Utilizing IMAGEREL relocations for synthetic IR constructs isn't
valuable, just clutter. While we are here, simplify HandlerType names
by making the numeric value for the 'adjective' part of the mangled name
instead of appending '.const', etc. The old scheme made for very long
global names and leads to wordy things like '.std_bad_alloc'
llvm-svn: 233503
There will be an explicit template instantiation in another translation
unit which will provide the definition of the VF/VB-Tables.
This fixes PR22932.
llvm-svn: 232680
The HandlerMap describes, to the runtime, what sort of catches surround
the try. In principle, this structure has to be emitted by the backend
because only it knows the layout of the stack (the runtime needs to know
where on the stack the destination of a copy lives, etc.) but there is
some C++ specific information that the backend can't reason about.
Stick this information in special LLVM globals with the relevant
"const", "volatile", "reference" info mangled into the name.
llvm-svn: 232538
Previously, we would error out on this code because the default argument
wasn't parsed until the end of Outer:
struct __declspec(dllexport) Outer {
struct __declspec(dllexport) Inner {
Inner(void *p = 0);
};
};
Now we do the checking on the closing brace of Outer instead of Inner.
llvm-svn: 232519
Qualifiers are located next to the TypeDescriptor in order to properly
ensure that a pointer type can only be caught by a more qualified catch
handler. This means that a catch handler of type 'const int *' requires
an RTTI object for 'int *'. We got this correct for 'throw' but not for
'catch'.
N.B. We don't currently have the means to store the qualifiers because
LLVM's EH strategy is tailored to the Itanium scheme. The Itanium ABI
stores qualifiers inside the type descriptor in such a way that the
manner of qualification is stored in addition to the pointee type's
descriptor. Perhaps the best way of modeling this for the MS ABI is
using an aggregate type to bundle the qualifiers with the descriptor?
This is tricky because we want to make it clear to the optimization
passes which catch handlers invalidate other handlers.
My current thoughts on a design for this is along the lines of:
{ { TypeDescriptor* TD, i32 QualifierFlags }, i32 MiscFlags }
The idea is that the inner most aggregate is all that is needed to
communicate that one catch handler might supercede another. The
'MiscFlags' field would be used to hold the bitpattern for the notion
that the 'catch' handler does not need to invoke a copy-constructor
because we are catching by reference.
llvm-svn: 232318
The MS ABI utilizes a compiler generated function called the "vector
constructor iterator" to construct arrays of objects with
non-trivial constructors/destructors. For this to work, the constructor
must follow a specific calling convention. A thunk must be created if
the default constructor has default arguments, is variadic or is
otherwise incompatible. This thunk is called the default constructor
closure.
N.B. Default constructor closures are only generated if the default
constructor is exported because clang itself does not utilize vector
constructor iterators. Failing to export the default constructor
closure will result in link/load failure if a translation unit compiled
with MSVC is on the import side.
Differential Revision: http://reviews.llvm.org/D8331
llvm-svn: 232229
std::make_exception_ptr calls std::__GetExceptionInfo in order to figure
out how to properly copy the exception object.
Differential Revision: http://reviews.llvm.org/D8280
llvm-svn: 232188
A nullptr exception object can be caught by any pointer type catch
handler. However, it is not possible to express this in the exception
info for the MS ABI. As a middle ground, allow such exception objects
to be caught with pointer-to-void catch handlers.
llvm-svn: 232069
This adds support for copy-constructor closures. These are generated
when the C++ runtime has to call a copy-constructor with a particular
calling convention or with default arguments substituted in to the call.
Because the runtime has no mechanism to call the function with a
different calling convention or know-how to evaluate the default
arguments at run-time, we create a thunk which will do all the
appropriate work and package it in a way the runtime can use.
Differential Revision: http://reviews.llvm.org/D8225
llvm-svn: 231952
Because the catchable type has a reference to its name, mangle the
location to ensure that two catchable types with different locations are
distinct.
llvm-svn: 231819
Find all unambiguous public classes of the exception object's class type
and reference all of their copy constructors. Yes, this is not
conforming but it is necessary in order to implement their ABI. This is
because the copy constructor is actually referenced by the metadata
describing which catch handlers are eligible to handle the exception
object.
N.B. This doesn't yet handle the copy constructor closure case yet,
that work is ongoing.
Differential Revision: http://reviews.llvm.org/D8101
llvm-svn: 231499
Throwing a C++ exception, under the MS ABI, is implemented using three
components:
- ThrowInfo structure which contains information like CV qualifiers,
what destructor to call and a pointer to the CatchableTypeArray.
- In a significant departure from the Itanium ABI, copying by-value
occurs in the runtime and not at the catch site. This means we need
to enumerate all possible types that this exception could be caught as
and encode the necessary information to convert from the exception
object's type to the catch handler's type. This includes complicated
derived to base conversions and the execution of copy-constructors.
N.B. This implementation doesn't support the execution of a
copy-constructor from within the runtime for now. Adding support for
that functionality is quite difficult due to things like default
argument expressions which may evaluate arbitrary code hiding in the
copy-constructor's parameters.
Differential Revision: http://reviews.llvm.org/D8066
llvm-svn: 231328
It is common for COM interface classes to be marked as 'novtable' to
tell the compiler that constructors and destructors should not reference
virtual function tables.
This commit implements this feature in clang.
llvm-svn: 227796
This attribute implies indicates that the function musttail calls
another function and returns whatever it returns. The return type of the
thunk is meaningless, as the thunk can dynamically call different
functions with different return types. So long as the callers bitcast
the thunk with the correct type, behavior is well defined.
This attribute was necessary to fix PR20944, where the indirect call
combiner noticed that the thunk returned void and replaced the results
of the indirect call instruction with undef.
Over-the-shoulder reviewed by David Majnemer.
llvm-svn: 226707
The llvm IR until recently had no support for comdats. This was a problem when
targeting C++ on ELF/COFF as just using weak linkage would cause quite a bit of
dead bits to remain on the executable (unless -ffunction-sections,
-fdata-sections and --gc-sections were used).
To fix the problem, llvm's codegen will just assume that any weak or linkonce
that is not in an explicit comdat should be output in one with the same name as
the global.
This unfortunately breaks cases like pr19848 where a weak symbol is not
xpected to be part of any comdat.
Now that we have explicit comdats in the IR, we can finally get both cases
right.
This first patch just makes clang give explicit comdats to GlobalValues where
t is allowed to.
A followup patch to llvm will then stop implicitly producing comdats.
llvm-svn: 225705
Rethrowing exceptions in the MS model is very simple: just call
_CxxThrowException with nullptr for both arguments.
N.B. They chose stdcall as the calling convention for x86 but cdecl for
all other platforms.
llvm-svn: 222733
The most complex aspect of the convention is the handling of homogeneous
vector and floating point aggregates. Reuse the homogeneous aggregate
classification code that we use on PPC64 and ARM for this.
This convention also has a C mangling, and we apparently implement that
in both Clang and LLVM.
Reviewed By: majnemer
Differential Revision: http://reviews.llvm.org/D6063
llvm-svn: 221006
Summary:
The Itanium ABI approach of using offset-to-top isn't possible with the
MS ABI, it doesn't have that kind of information lying around.
Instead, we do the following:
- Call the virtual deleting destructor with the "don't delete the object
flag" set. The virtual deleting destructor will return a pointer to
'this' adjusted to the most derived class.
- Call the global delete using the adjusted 'this' pointer.
Reviewers: rnk
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D5996
llvm-svn: 220993
This eliminates some i8* GEPs and makes the IR that clang emits a bit
more canonical. More work is needed for vftables, but that isn't a clear
win so I plan to send it for review.
llvm-svn: 220398
This commit changes the way we blacklist functions in ASan, TSan,
MSan and UBSan. We used to treat function as "blacklisted"
and turned off instrumentation in it in two cases:
1) Function is explicitly blacklisted by its mangled name.
This part is not changed.
2) Function is located in llvm::Module, whose identifier is
contained in the list of blacklisted sources. This is completely
wrong, as llvm::Module may not correspond to the actual source
file function is defined in. Also, function can be defined in
a header, in which case user had to blacklist the .cpp file
this header was #include'd into, not the header itself.
Such functions could cause other problems - for instance, if the
header was included in multiple source files, compiled
separately and linked into a single executable, we could end up
with both instrumented and non-instrumented version of the same
function participating in the same link.
After this change we will make blacklisting decision based on
the SourceLocation of a function definition. If a function is
not explicitly defined in the source file, (for example, the
function is compiler-generated and responsible for
initialization/destruction of a global variable), then it will
be blacklisted if the corresponding global variable is defined
in blacklisted source file, and will be instrumented otherwise.
After this commit, the active users of blacklist files may have
to revisit them. This is a backwards-incompatible change, but
I don't think it's possible or makes sense to support the
old incorrect behavior.
I plan to make similar change for blacklisting GlobalVariables
(which is ASan-specific).
llvm-svn: 219997
David Majnemer