Conditionally use an integral cast for BodyFarm support for OSAtomicCompareAndSwap if the return type is not a boolean.

llvm-svn: 165774

#undef only occurs if that submodule is imported.

llvm-svn: 165773

llvm-svn: 165772

has none of its own. Factor in Doug's comments.
// rdar://12378793

llvm-svn: 165771

Updates to llvm/Support/Casting.h have rendered these classof()'s
irrelevant.

llvm-svn: 165770

Somewhat troublingly, without this implemented, the check inside
isa_impl<> would silently use the parent's `classof()` when determining
whether it was okay to downcast from the parent to the child!

Bug analysis:

A build failure after removing the parent's `classof()` initially
alerted me to the bug, after which a little bit of thinking and reading
of the code identified the root cause.

The compiler could be made to prevent this bug from happening if there
were a way to ensure that in the code

    template <typename To, typename From, typename Enabler = void>
    struct isa_impl {
      static inline bool doit(const From &Val) {
        return To::classof(&Val);
      }
    };

that `To::classof` is actually inside the class `To`, and not in a base
class. I am not aware of a way to check this in C++. If there is a means
to perform that check, please bring it up on the list and this will be
fixed.

There is a high likelihood that there are other instances of this same
bug in the codebase.

llvm-svn: 165769

* Fix confusing explanation regarding abstract classes.

* Clarify auto-upcasting and why `Shape` doesn't need a `classof()`.

* Add section `Rules of Thumb` with some quick summary tips.

llvm-svn: 165768

isa<> et al. automatically infer when the cast is an upcast (including a
self-cast), so these are no longer necessary.

llvm-svn: 165767

Recent changes to isa<>/dyn_cast<> have made unnecessary those classof()
of the form:

    static bool classof(const Foo *) { return true; }

Accordingly, remove mention of such classof() from the documentation.

llvm-svn: 165766

Additionally, all such cases are handled with no dynamic check.

All `classof()` of the form

    class Foo {
      [...]
      static bool classof(const Bar *) { return true; }
      [...]
    }

where Foo is an ancestor of Bar are no longer necessary.
Don't write them!

Note: The exact test is `is_base_of<Foo, Bar>`, which is non-strict, so
that Foo is considered an ancestor of itself.

This leads to the following rule of thumb for LLVM-style RTTI:

    The argument type of `classof()` should be a strict ancestor.

For more information about implementing LLVM-style RTTI, see
docs/HowToSetUpLLVMStyleRTTI.rst

llvm-svn: 165765

This classof() is effectively saying that a MachineCodeEmitter "is-a"
JITEmitter, but JITEmitter is in fact a descendant of
MachineCodeEmitter, so this is not semantically correct. Consequently,
none of the assertions that rely on these classof() actualy check
anything.

Remove the RTTI (which didn't actually check anything) and use
static_cast<> instead.

Post-Mortem Bug Analysis
========================

Cause of the bug
----------------

r55022 appears to be the source of the classof() and assertions removed
by this commit. It aimed at removing some dynamic_cast<> that were
solely in the assertions. A typical diff hunk from that commit looked
like:

  -  assert(dynamic_cast<JITEmitter*>(MCE) && "Unexpected MCE?");
  -  JITEmitter *JE = static_cast<JITEmitter*>(getCodeEmitter());
  +  assert(isa<JITEmitter>(MCE) && "Unexpected MCE?");
  +  JITEmitter *JE = cast<JITEmitter>(getCodeEmitter());

Hence, the source of the bug then seems to be an attempt to replace
dynamic_cast<> with LLVM-style RTTI without properly setting up the
class hierarchy for LLVM-style RTTI. The bug therefore appears to be
simply a "thinko".

What initially indicated the presence of the bug
------------------------------------------------

After implementing automatic upcasting for isa<>, classof() functions of
the form

  static bool classof(const Foo *) { return true; }

were removed, since they only serve the purpose of optimizing
statically-OK upcasts. A subsequent recompilation triggered a build
failure on the isa<> tests within the removed asserts, since the
automatic upcasting (correctly) failed to substitute this classof().

Key to pinning down the root cause of the bug
---------------------------------------------

After being alerted to the presence of the bug, some thought about the
semantics which were being asserted by the buggy classof() revealed that
it was incorrect.

How the bug could have been prevented
-------------------------------------

This bug could have been prevented by better documentation for how to
set up LLVM-style RTTI. This should be solved by the recently added
documentation HowToSetUpLLVMStyleRTTI. However, this bug suggests that
the documentation should clearly explain the contract that classof()
must fulfill. The HowToSetUpLLVMStyleRTTI already explains this
contract, but it is a little tucked away. A future patch will expand
that explanation and make it more prominent.

There does not appear to be a simple way to have the compiler prevent
this bug, since fundamentally it boiled down to a spurious classof()
where the programmer made an erroneous statement about the conversion.
This suggests that perhaps the interface to LLVM-style RTTI of classof()
is not the best. There is already some evidence for this, since in a
number of places Clang has classof() forward to classofKind(Kind K)
which evaluates the cast in terms of just the Kind. This could probably
be generalized to simply a `static const Kind MyKind;` field in leaf
classes and `static const Kind firstMyKind, lastMyKind;` for non-leaf
classes, and have the rest of the work be done inside Casting.h,
assuming that the Kind enum is laid out in a preorder traversal of the
inheritance tree.

llvm-svn: 165764

This only applies if the type has a name. (we could potentially do something
crazy with decltype in C++11 to qualify members of unnamed types but that
seems excessive)

It might be nice to also suggest a fixit for "&this->i", "&foo->i",
and "&foo.i" but those expressions produce 'bound' member functions that have
a different AST representation & make error recovery a little trickier. Left
as future work.

llvm-svn: 165763

llvm-svn: 165762

llvm-svn: 165761

llvm-svn: 165760

When all cases of a switch statement are dead, the weights vector only has one
element, and we will get an ssertion failure when calling createBranchWeights.

llvm-svn: 165759

llvm-svn: 165758

llvm-svn: 165757

Fixed an issue where we would try to launch an application twice and the second failure would cover up the first.

llvm-svn: 165756

llvm-svn: 165755

change in the LLDB target data API.

llvm-svn: 165754

llvm-svn: 165753

reimplemented in the AsmParser where it belongs.

llvm-svn: 165752

now unused static helper function.

The test case needs to be remove temporarily until I can better filter memory
operands that aren't actual variable reference.

llvm-svn: 165751

llvm-svn: 165747

only with modules, when two disjoint modules #define the same
identifier to different token sequences.

llvm-svn: 165746

llvm-svn: 165744

objc_atomicCompareAndSwap.

llvm-svn: 165743

llvm-svn: 165742

llvm-svn: 165741

Fixed an indentation issue that only shows up when dumping .o files that use linked addresses (DWARF in .o files with debug map).

llvm-svn: 165740

to the instruction position.  The old encoding would give an absolute
ID which counts up within a function, and only resets at the next function.

I.e., Instead of having:

... = icmp eq i32 n-1, n-2
br i1 ..., label %bb1, label %bb2

it will now be roughly:

... = icmp eq i32 1, 2
br i1 1, label %bb1, label %bb2

This makes it so that ids remain relatively small and can be encoded
in fewer bits.

With this encoding, forward reference operands will be given
negative-valued IDs.  Use signed VBRs for the most common case
of forward references, which is phi instructions.

To retain backward compatibility we bump the bitcode version
from 0 to 1 to distinguish between the different encodings.

llvm-svn: 165739

llvm-svn: 165736

in c-index-test. index_enteredMainFile is not invoked when indexing a
module file.

llvm-svn: 165735

llvm-svn: 165734

llvm-svn: 165733

llvm-svn: 165732

llvm-svn: 165731

Dynamic type code must be efficient and fast. Now it is.

Added ObjC v1 support for getting the complete list of ISA values.

The main flow of the AppleObjCRuntime subclasses is now they must override "virtual bool UpdateISAToDescriptorMap_Impl();". This function will update the complete list of ISA values and create ClassDescriptorSP objects for each one. Now we have the complete list of valid ISA values which we can use for verification when doing dynamic typing.

Refactored a bunch of stuff so that the AppleObjCRuntime subclasses don't have to implement as many functions as they used to.

llvm-svn: 165730

associated with deserializing macro history for an identifier.

llvm-svn: 165729