Commit Graph

37 Commits

Author SHA1 Message Date
Piotr Padlewski a68a78751f Generating available_externally vtables for outline virtual functions
Generating available_externally vtables for optimizations purposes.
Unfortunatelly ItaniumABI doesn't guarantee that we will be able to
refer to virtual inline method by name.
But when we don't have any inline virtual methods, and key function is
not defined in this TU, we can generate that there will be vtable and
mark it as available_externally.

This is patch will help devirtualize better.
Differential Revision: http://reviews.llvm.org/D11441

llvm-svn: 243090
2015-07-24 04:04:49 +00:00
Rafael Espindola cb92c19fc4 Use a trivial comdat for C++ tables.
This produces comdats for vtables, typeinfo, typeinfo names, and vtts.

When combined with llvm not producing implicit comdats, not doing this would
cause code bloat on ELF and link errors on COFF.

llvm-svn: 226227
2015-01-15 23:18:01 +00:00
John McCall 57420b320c type_info objects are not unnamed_addr: the ABI requires us to
unique them and permits the implementation of dynamic_cast (and
anything else which knows it's working with a complete class
type) to compare their addresses directly.

rdar://16005328

llvm-svn: 201020
2014-02-08 03:26:05 +00:00
John McCall 8f80a61914 Remove the -fhidden-weak-vtables -cc1 option. It was dead,
gross, and increasingly replaced through other mechanisms.

llvm-svn: 201011
2014-02-08 00:41:16 +00:00
Rafael Espindola ee6aa0c62e Don't emit an available_externally vtable pointing to linkonce_odr funcs.
This fixes pr13124.

From the discussion at
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2012-June/022606.html
we know that we cannot make funcions in a weak_odr vtable also weak_odr. They
should remain linkonce_odr.

The side effect is that we cannot emit a available_externally vtable unless we
also emit a copy of the function. This also has an issue: If codegen is going
to output a function, sema has to mark it used. Given llvm.org/pr9114, it looks
like sema cannot be more aggressive at marking functions used because
of vtables.

This leaves us with a few unpleasant options:

* Marking functions in vtables used if possible. This sounds a bit sloppy, so
  we should avoid it.
* Producing available_externally vtables only when all the functions in it are
  already used or weak_odr. This would cover cases like

--------------------
struct foo {
  virtual ~foo();
};
struct bar : public foo {
  virtual void zed();
};
void f() {
  foo *x(new bar);
  delete x;
}
void g(bar *x) {
  x->~bar(); // force the destructor to be used
}
--------------------------

and

----------------------------------
template<typename T>
struct bar {
  virtual ~bar();
};
template<typename T>
bar<T>::~bar() {
}

// make the destructor weak_odr instead of linkonce_odr
extern template class bar<int>;

void f() {
  bar<int> *x(new bar<int>);
  delete x;
}
----------------------------

These look like corner cases, so it is unclear if it is worth it.

* And finally: Just nuke this optimization. That is what this patch implements.

llvm-svn: 189852
2013-09-03 21:05:13 +00:00
Rafael Espindola 0f02285bc5 Use CHECK-DAG in this test.
llvm-svn: 189280
2013-08-26 22:10:31 +00:00
Richard Smith 65fd2a4e90 Emit vtables for an extern template class as available_externally, not as
linkonce_odr. Emit construction vtables as internal in this case, since the ABI
does not guarantee that they will be availble externally.

llvm-svn: 175330
2013-02-16 00:51:21 +00:00
Chris Lattner 57540c5be0 fix a bunch of comment typos found by codespell. Patch by
Luis Felipe Strano Moraes!

llvm-svn: 129559
2011-04-15 05:22:18 +00:00
Anders Carlsson 5963024ff6 Give VTTs the right visibility.
llvm-svn: 124540
2011-01-29 19:34:19 +00:00
Anders Carlsson 571e2ad042 Mark VTables and RTTI data linkonce_odr instead of weak_odr, with the exception of explicit template instantiations, which have to be weak_odr.
This fixes PR6996.

llvm-svn: 124089
2011-01-24 00:46:19 +00:00
Rafael Espindola facb7d0ade Also set unnamed_addr on declarations.
llvm-svn: 123531
2011-01-15 08:23:14 +00:00
Rafael Espindola d09776b945 Only add unnamed_addr to definitions.
llvm-svn: 123354
2011-01-13 01:12:55 +00:00
Rafael Espindola 25f4620c67 Set unnamed_addr in every type info.
llvm-svn: 123293
2011-01-11 23:55:05 +00:00
Rafael Espindola b1e879c80f Set unnamed_addr for type infos that we are confortable marking as hidden. I
think it is safe to mark all type infos with unnamed_addr, but I am not sure.

llvm-svn: 123275
2011-01-11 21:44:37 +00:00
Rafael Espindola 5674c644cf Add unnamed_addr to vtables.
llvm-svn: 123272
2011-01-11 21:10:26 +00:00
Argyrios Kyrtzidis 0c34b138df Make sure the VTables for template instantiations are emitted even if the key function doesn't have a body.
llvm-svn: 116186
2010-10-11 03:25:57 +00:00
John McCall b3732bb3b7 Just disable the hidden-visibility optimization for now by hiding it behind
a -cc1 option.  The Darwin linker complains about mixed visibility when linking
gcc-built objects with clang-built objects, and the optimization isn't really
that valuable.  Platforms with less ornery linkers can feel free to enable this.

llvm-svn: 110979
2010-08-12 23:36:15 +00:00
John McCall 5513fce96b It turns out that linkers (at least, the Darwin linker) don't necessarily
do the right thing with mixed-visibility symbols, so disable the visibility
optimization where that's possible, i.e. with template classes (since it's
possible that an arbitrary template might be subject to an explicit
instantiation elsewhere).  447.dealII actually does this.

I've put the code under an option that's currently not hooked up to anything.

llvm-svn: 110374
2010-08-05 20:39:18 +00:00
John McCall e16adc2b1e Emit standard-library RTTI with external linkage, not weak_odr.
Apply hidden visibility to most RTTI;  libstdc++ does not rely on exact
pointer equality for the type info (just the type info names).  Apply
the same optimization to RTTI that we do to vtables.

Fixes PR5962.

llvm-svn: 110192
2010-08-04 08:34:44 +00:00
John McCall 8a705c15d9 Extend the hidden-visibility vtables optimization to template classes that
haven't been explicitly instantiated.

llvm-svn: 110189
2010-08-04 06:38:15 +00:00
John McCall 5696d6d316 Emit weak vtables of non-template classes with hidden visibility.
llvm-svn: 110107
2010-08-03 07:24:12 +00:00
Daniel Dunbar 532177685a IRgen/C++: When mark vtables used, make sure to still append to the VTableUse array if we promote a vtable from being just used to having its definition required. This ensures that we properly inform the consumer about whether the vtable is required or not, previously we could fail to do so when the vtable was in the VTableUses array before the decl which marked it as required.
- I think this can be cleaned up, since this means we may notify the consumer about the vtable twice, but I didn't see an easy fix for this without more substantial refactoring.
 - Doug, please review!

llvm-svn: 104577
2010-05-25 00:33:13 +00:00
Douglas Gregor 88d292ccb8 Rework when and how vtables are emitted, by tracking where vtables are
"used" (e.g., we will refer to the vtable in the generated code) and
when they are defined (i.e., because we've seen the key function
definition). Previously, we were effectively tracking "potential
definitions" rather than uses, so we were a bit too eager about emitting
vtables for classes without key functions. 

The new scheme:
  - For every use of a vtable, Sema calls MarkVTableUsed() to indicate
  the use. For example, this occurs when calling a virtual member
  function of the class, defining a constructor of that class type,
  dynamic_cast'ing from that type to a derived class, casting
  to/through a virtual base class, etc.
  - For every definition of a vtable, Sema calls MarkVTableUsed() to
  indicate the definition. This happens at the end of the translation
  unit for classes whose key function has been defined (so we can
  delay computation of the key function; see PR6564), and will also
  occur with explicit template instantiation definitions.
 - For every vtable defined/used, we mark all of the virtual member
 functions of that vtable as defined/used, unless we know that the key
 function is in another translation unit. This instantiates virtual
 member functions when needed.
  - At the end of the translation unit, Sema tells CodeGen (via the
  ASTConsumer) which vtables must be defined (CodeGen will define
  them) and which may be used (for which CodeGen will define the
  vtables lazily). 

From a language perspective, both the old and the new schemes are
permissible: we're allowed to instantiate virtual member functions
whenever we want per the standard. However, all other C++ compilers
were more lazy than we were, and our eagerness was both a performance
issue (we instantiated too much) and a portability problem (we broke
Boost test cases, which now pass).

Notes:
  (1) There's a ton of churn in the tests, because the order in which
  vtables get emitted to IR has changed. I've tried to isolate some of
  the larger tests from these issues.
  (2) Some diagnostics related to
  implicitly-instantiated/implicitly-defined virtual member functions
  have moved to the point of first use/definition. It's better this
  way.
  (3) I could use a review of the places where we MarkVTableUsed, to
  see if I missed any place where the language effectively requires a
  vtable.

Fixes PR7114 and PR6564.

llvm-svn: 103718
2010-05-13 16:44:06 +00:00
Rafael Espindola 8e7ca8e0b1 Don't produce a vtable for a class if we have an explicit template instantiation declaration and no key function. We will produce the vtable at the explicit template instantiation.
Fixes PR6748

llvm-svn: 100266
2010-04-03 04:26:42 +00:00
Anders Carlsson 85e64359df Flip the switch and use the new vtable layout code for everything. I've verified that this passes a self-host but I'll let the bots self host as well before removing the now dead code.
llvm-svn: 99861
2010-03-30 02:21:54 +00:00
Eli Friedman 5866fe306d Fix for PR5967: Make const-marking for LLVM globals correct for cases requiring
run-time initialization, and emit run-time initializers aggresively to avoid
ordering issues with deferred globals.

llvm-svn: 92976
2010-01-08 00:50:11 +00:00
Douglas Gregor 3a08dcc156 Test linkage of typeinfo and typeinfo names for class templates
llvm-svn: 92897
2010-01-07 04:09:30 +00:00
Douglas Gregor d01472beee Revert my available_externally vtables experiment. It's breaking the LLVM-with-Clang build with linker errors that I have yet to investigate.
llvm-svn: 92822
2010-01-06 04:50:56 +00:00
Douglas Gregor 1a68ab6c83 Make use of available_externally linkage for vtables when the
non-inline key function of a class template instantiation, when no key
function is present, the class template instantiation itself was
instantiated with an explicit instantiation declaration (aka extern
template). I'm fairly certain that the C++0x specification gives us
this lattitude, although GCC doesn't take advantage of it.

llvm-svn: 92779
2010-01-05 21:40:05 +00:00
Douglas Gregor a318efd1f2 Improve key-function computation for templates. In particular:
- All classes can have a key function; templates don't change that.
  non-template classes when computing the key function.
  - We always mark all of the virtual member functions of class
  template instantiations. 
  - The vtable for an instantiation of a class template has weak
  linkage. 

We could probably use available_externally linkage for vtables of
classes instantiated by explicit instantiation declarations (extern
templates), but GCC doesn't do this and I'm not 100% that the ABI
permits it.

llvm-svn: 92753
2010-01-05 19:06:31 +00:00
Daniel Dunbar 8fbe78f6fc Update tests to use %clang_cc1 instead of 'clang-cc' or 'clang -cc1'.
- This is designed to make it obvious that %clang_cc1 is a "test variable"
   which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
   can be useful to redefine what gets run as 'clang -cc1' (for example, to set
   a default target).

llvm-svn: 91446
2009-12-15 20:14:24 +00:00
Eli Friedman 3ace52b3a7 Fix linkage of type info and vtable for classes without linkage.
llvm-svn: 91152
2009-12-11 20:48:18 +00:00
Anders Carlsson fd7dfeb779 Improve linkage of RTTI data structures. Introduce CodeGenModule::GetAddrOfRTTI which figures out the right linkage of the RTTI information for the given type and whether it should be defined or not. I will migrate clients over to GetAddrOfRTTI in subsequent commits (with tests).
llvm-svn: 91098
2009-12-11 02:46:30 +00:00
Anders Carlsson 232324c5c0 More linkage improvements.
llvm-svn: 90687
2009-12-06 00:53:22 +00:00
Anders Carlsson 0ab79e22ab If a class does not have a key function, its linkage should be weak_odr.
llvm-svn: 90680
2009-12-05 22:24:38 +00:00
Anders Carlsson 58b271d450 Use createGlobalVariable for creating vtable variables too.
llvm-svn: 90679
2009-12-05 22:19:10 +00:00
Anders Carlsson 21bbc1e705 Factor vtable related GlobalVariable creation out into a separate function. Add vtable linkage test.
llvm-svn: 90667
2009-12-05 17:04:47 +00:00