When unconditionally casting from a base to a final derived class, e.g. `base as! Derived`, the program did not abort with a trap.
Instead the resulting null-pointer caused a crash later in the program.
This fix inserts a trap condition for the failing case of such a cast.
rdar://151462303
Certain dynamic casts cannot work safely with isolated conformances,
regardless of what executor the code runs on. For such cases, reject
all attempts to conform to the type.
Reformatting everything now that we have `llvm` namespaces. I've
separated this from the main commit to help manage merge-conflicts and
for making it a bit easier to read the mega-patch.
This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".
I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.
As an optimization, there is a fast-cast to non-final classes that just
compares isa pointers. If the source of the cast is an Optional<class>,
though, it's not allowed to "directly compare the isa-pointer"; because
the source might be Optional.none, i.e. null.
Add a check for nil when emitting the fast class cast.
rdar://108614878
When casting a class instance to a final class, we can directly compare the isa-pointer with address of the metadata.
This avoids a call to `swift_dynamicCastClass`.
It also avoids a call to the metadata accessor of the class (which calls `swift_getInitializedObjCClass`).
For comparing the metadata pointers it's not required that the metadata is fully initialized.
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
rdar://22666588
This change removes a comparison and a branch on every virtual call. Before this
change we were generating code for comparing the metadata to figure out if the
incoming instance is an 'exact' cast, and then we checked if the result of the
cast was zero. This is unnecessary because we can simply reuse the result of the
exact metadata comparison. Moreover, we know that the metadata instance can't be
zero because we've emitted a load to that address that did not trap.
%1 = getelementptr inbounds %C4main1X, %C4main1X* %0 ...
%.metadata = load %swift.type*, %swift.type** %1 // Loading %0
%2 = icmp eq %swift.type* %.metadata, bitcast (...)
%3 = icmp ne %C4main1X* %0, null ; <----------- %0 can't be null.
%4 = and i1 %3, %2
br i1 %4, label %5, label %7
Swift SVN r31920
The code path here is mostly the same as the class cast case--we have to test the ObjC class (if it is a class) against any ObjC protocols, then look up conformances for the native protocols.
Swift SVN r23184
- A spot fix in SILGen for reabstracting the result of a downcast, which fixes checked casts to function types.
- Associate the layout information in type metadata records with the most abstract representation of the type. This is the correct thing to do in cases where we need the metadata as a tag for an opaque value--if we store a value in an Any, or pass it as an unconstrained generic parameter, we must maximally reabstract it. This fixes the value semantics of existentials containing trivial metatypes.
- To ensure that we get runtime layout of structs and enums correct when they contain reabstractable types, introduce a "metadata for layout" concept, which doesn't need to describe the canonical metadata for the type, but only needs to describe a type with equivalent layout and value semantics. This is a correctness fix that allows us to correctly lay out generic types containing dependent tuples and functions, and although we don't really take advantage of it here, it's also a potential runtime performance win down the road, because we could potentially produce direct metadata for a primitive type that's layout-equivalent with a runtime-instantiated type. To aid in type safety here, push SILType deeper into IRGen in places where we potentially care about specific representations of types.
- Finally, fix an inconsistency between the runtime and IRGen's concept of what spare bits unmanaged references and thick metatypes have.
Together, these fixes address rdar://problem/16406907, rdar://problem/17822208, rdar://problem/18189508, and likely many other related issues, and also fixes crash suite cases 012 and 024.
Swift SVN r21963
