Summary:
The MSVC ABI appears to mangle the lexical scope into the names of
statics. Specifically, a counter is incremented whenever a scope is
entered where things can be declared in such a way that an ambiguity can
arise. For example, a class scope inside of a class scope doesn't do
anything interesting because the nested class cannot collide with
another nested class.
There are problems with this scheme:
- It is unreliable. The counter is only incremented when a previously
never encountered scope is entered. There are cases where this will
cause ambiguity amongst declarations that have the same name where one
was introduced in a deep scope while the other was introduced right
after in the previous lexical scope.
- It is wasteful. Statements like: {{{{{{{ static int foo = a; }}}}}}}
will make the mangling of "foo" larger than it need be because the
scope counter has been incremented many times.
Because of these problems, and practical implementation concerns. We
choose not to implement this scheme if the local static or local type
isn't visible. The mangling of these declarations will look very
similar but the numbering will make far more sense, this scheme is
lifted from the Itanium ABI implementation.
Reviewers: rsmith, doug.gregor, rnk, eli.friedman, cdavis5x
Reviewed By: rnk
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D2953
llvm-svn: 202951
These features are new in VS 2013 and are necessary in order to layout
std::ostream correctly. Currently we have an ABI incompatibility when
self-hosting with the 2013 stdlib in our convertible_fwd_ostream wrapper
in gtest.
This change adds another implicit attribute, MSVtorDispAttr, because
implicit attributes are currently the best way to make sure the
information stays on class templates through instantiation.
Reviewers: majnemer
Differential Revision: http://llvm-reviews.chandlerc.com/D2746
llvm-svn: 201274
Introduce a notion of a 'current representation method' for
pointers-to-members.
When starting out, this is set to 'best case' (representation method is
chosen by examining the class, selecting the smallest representation
that would work given the class definition or lack thereof).
This pragma allows the translation unit to dictate exactly what
representation to use, similar to how the inheritance model keywords
operate.
N.B. PCH support is forthcoming.
Differential Revision: http://llvm-reviews.chandlerc.com/D2723
llvm-svn: 201105
Member pointers are mangled as they would be represented at runtime.
They can be a single integer literal, single decl, or a tuple with some
more numbers tossed in. With Clang today, most of those numbers will be
zero because we reject pointers to members of virtual bases.
This change required moving VTableContextBase ownership from
CodeGenVTables to ASTContext, because mangling now depends on vtable
layout.
I also hoisted the inheritance model helpers up to be inline static
methods of MSInheritanceAttr. This makes the AST code that deals with
member pointers much more readable.
MSVC doesn't appear to have stable manglings of null member pointers:
- Null data memptrs in function templates have a mangling collision with
the first field of a non-polymorphic single inheritance class.
- The mangling of null data memptrs changes if you add casts.
- Large null function memptrs in class templates crash MSVC.
Clang uses the class template mangling for null data memptrs and the
function template mangling for null function memptrs to deal with this.
Reviewers: majnemer
Differential Revision: http://llvm-reviews.chandlerc.com/D2695
llvm-svn: 200857
With this change, we give different results for __alignof than MSVC, but
our record layout is compatible.
Some data member pointers also now have a size that is not a multiple of
their alignment.
Fixes PR18618.
Reviewers: majnemer
Differential Revision: http://llvm-reviews.chandlerc.com/D2669
llvm-svn: 200585
We would previously allow inappropriate inheritance keywords to appear
on class declarations. We would also allow inheritance keywords on
templates which were not fully specialized; this was divergent from
MSVC.
Differential Revision: http://llvm-reviews.chandlerc.com/D2585
llvm-svn: 200423
This reverts commit r199475 (which reverted r199416) with fixes for the
breakages.
We wouldn't lock an inheritance model if we saw a pointer-to-member
formed as a result of the address-of operator.
llvm-svn: 199482
The MSVC ABI is rather finicky about the exact representation of it's
pointer-to-member representation. The exact position of when and where
it will go with one representation versus another appears to be when it
desires the pointer-to-member to be complete.
To properly implement this in clang, do several things:
- Give up on tracking the polymorphic nature of the class. It isn't
useful to Sema and is only pertinent when choosing CodeGen-time
details like whether the field-offset can be 0 instead of -1.
- Insist on locking-in the inheritance model when we ask our
pointer-to-member type to be complete. From there, grab the
underlying CXXRecordDecl and try to make *that* complete. Once we've
done this, we can calculate it's inheritance model and apply it using
an attribute.
N.B. My first bullet point is a lie. We will eventually care about the
specifics of whether or not a CXXRecordDecl is or is not polymorphic
because MSVC compatible mangling of such things depends on it. However,
I believe we will handle this in a rather different way.
llvm-svn: 199416
encodes the canonical rules for LLVM's style. I noticed this had drifted
quite a bit when cleaning up LLVM, so wanted to clean up Clang as well.
llvm-svn: 198686
Static locals requiring initialization are not thread safe on Windows.
Unfortunately, it's possible to create static locals that are actually
externally visible with inline functions and templates. As a result, we
have to implement an initialization guard scheme that is compatible with
TUs built by MSVC, which makes thread safety prohibitively difficult.
MSVC's scheme is that every function that requires a guard gets an i32
bitfield. Each static local is assigned a bit that indicates if it has
been initialized, up to 32 bits, at which point a new bitfield is
created. MSVC rejects inline functions with more than 32 static locals,
and the externally visible mangling (?_B) only allows for one guard
variable per function.
On Eli's recommendation, I used MangleNumberingContext to track which
bit each static corresponds to.
Implements PR16888.
Reviewers: rjmccall, eli.friedman
Differential Revision: http://llvm-reviews.chandlerc.com/D1416
llvm-svn: 190427
Summary:
Handles all inheritance models for both data and function member
pointers.
Also implements isZeroInitializable() and refactors some of the null
member pointer code.
MSVC supports converting member pointers through virtual bases, which
clang does not (yet?) support. Implementing that extension is covered
by http://llvm.org/15713
Reviewers: rjmccall
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D613
llvm-svn: 179305
Summary:
This makes it possible to share code between lib/AST/MicrosoftCXXABI.cpp
and lib/CodeGen/MicrosoftCXXABI.cpp. No functionality change.
Also adds comments about the layout of the member pointer structs as I
currently understand them.
Reviewers: rjmccall
CC: timurrrr, cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D590
llvm-svn: 178548
Summary:
This also relaxes the requirement on Windows that the member pointer
class type be a complete type (http://llvm.org/PR12070). We still ask
for a complete type to instantiate any templates (MSVC does this), but
if that fails we continue as normal, relying on any inheritance
attributes on the declaration.
Reviewers: rjmccall
CC: triton, timurrrr, cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D568
llvm-svn: 178283
builtin types (When requested). This is another step toward making
ASTUnit build the ASTContext as needed when loading an AST file,
rather than doing so after the fact. No actual functionality change (yet).
llvm-svn: 138985
Craig Topper