There's a buggy SIL verifier check that was previously tautological,
and it turns out that it's violated, apparently harmlessly. Since it
was already doing nothing, I've commented it out temporarily while
I figure out the right way to fix SILGen to get the invariant right.
This centralizes the entrypoints for creating SILFunctions. Creating a
SILFunction is intimately tied to a specific SILModule, so it makes sense to
either centralize the creation on SILModule or SILFunction. Since a SILFunction
is in a SILModule, it seems more natural to put it on SILModule.
I purposely created a new override on SILMod that exactly matches the signature
of SILFunction::create so that beyond the extra indirection through SILMod, this
change should be NFC. We can refactor individual cases in later iterations of
refactoring.
The drivers for this change are providing a simpler API to SIL pass
authors, having a more efficient of the in-memory representation,
and ruling out an entire class of common bugs that usually result
in hard-to-debug backend crashes.
Summary
-------
SILInstruction
Old New
+---------------+ +------------------+ +-----------------+
|SILInstruction | |SILInstruction | |SILDebugLocation |
+---------------+ +------------------+ +-----------------+
| ... | | ... | | ... |
|SILLocation | |SILDebugLocation *| -> |SILLocation |
|SILDebugScope *| +------------------+ |SILDebugScope * |
+---------------+ +-----------------+
We’re introducing a new class SILDebugLocation which represents the
combination of a SILLocation and a SILDebugScope.
Instead of storing an inline SILLocation and a SILDebugScope pointer,
SILInstruction now only has one SILDebugLocation pointer. The APIs of
SILBuilder and SILDebugLocation guarantees that every SILInstruction
has a nonempty SILDebugScope.
Developer-visible changes include:
SILBuilder
----------
In the old design SILBuilder populated the InsertedInstrs list to
allow setting the debug scopes of all built instructions in bulk
at the very end (as the responsibility of the user). In the new design,
SILBuilder now carries a "current debug scope" state and immediately
sets the debug scope when an instruction is inserted.
This fixes a use-after-free issue with with SIL passes that delete
instructions before destroying the SILBuilder that created them.
Because of this, SILBuilderWithScopes no longer needs to be a template,
which simplifies its call sites.
SILInstruction
--------------
It is neither possible or necessary to manually call setDebugScope()
on a SILInstruction any more. The function still exists as a private
method, but is only used when splicing instructions from one function
to another.
Efficiency
----------
In addition to dropping 20 bytes from each SILInstruction,
SILDebugLocations are now allocated in the SILModule's bump pointer
allocator and are uniqued by SILBuilder. Unfortunately repeat compiles
of the standard library already vary by about 5% so I couldn’t yet
produce reliable numbers for how much this saves overall.
rdar://problem/22017421
If the compiler can prove that a throwing function actually does not throw it can
replace a try_apply with an "apply [nothrow]". Such an apply_inst calls a function
with an error result but does not have the overhead of checking for the error case.
Currently this flag is not set, yet.
Swift SVN r31151
dealloc_ref [destructor] is the existing behavior. It expects the
reference count to have reached zero and the isDeallocating bit to
be set.
The new [constructor] variant first drops the initial strong
reference.
This allows DI to properly free uninitialized instances in
constructors. Previously this would fail with an assertion if the
runtime was built with debugging enabled.
Progress on <rdar://problem/21991742>.
Swift SVN r31142
This flag is required for performing the propagation of global and static "let" values into their uses.
Let variables have now a [let] attribute in the SIL textual form.
Swift SVN r30153
We need a SIL level unsafe cast that supports arbitrary usage of
UnsafePointer, generalizes Builtin.reinterpretCast, and has the same
semantics on generic vs. nongeneric code. In other words, we need to
be able to promote the cast of an address type to the cast of an
object type without changing semantics, and that cast needs to support
types that are not layout identical.
This patch introduces an unchecked_bitwise_cast instruction for that
purpose. It is different from unsafe_addr_cast, which has been our
fall-back "unknown" cast in the past. With unchecked_bitwise_cast we
cannot assume layout or RC identity. The cast implies a store and
reload of the value to obtain the low order bytes. I know that
bit_cast is just an abbreviation for bitwise_cast, but we use
"bitcast" throught to imply copying a same sized value. No one could
come up with a better name for copying an objects low bytes via:
@addr = alloca $wideTy
store @addr, $wideTy
load @addr, $narrowTy
Followup patches will optimize unchecked_bitwise_cast into more
semantically useful unchecked casts when enough type information is
present. This way, the optimizer will rarely need to be taught about
the bitwise case.
Swift SVN r29510
Still no implementation yet; we'll need to renovate how boxes work a bit to make them projectable (and renovate SILGen to generate typed boxes for the insn to be useful).
Swift SVN r29490
This reverts commit r29475 because it conflicts with reverting r29474,
and it looks like that commit is breaking the build of the SpriteKit
overlay.
Swift SVN r29481
Still no implementation yet; we'll need to renovate how boxes work a bit to make them projectable (and renovate SILGen to generate typed boxes for the insn to be useful).
Swift SVN r29475
Make unqualified lookup always provide a declaration for the things it
finds, rather than providing either a module or a declaration. Unify
various code paths in our type checker now that module declarations
come in with the other declarations.
Swift SVN r28286
Preparation to fix <rdar://problem/18151694> Add Builtin.checkUnique
to avoid lost Array copies.
This adds the following new builtins:
isUnique : <T> (inout T[?]) -> Int1
isUniqueOrPinned : <T> (inout T[?]) -> Int1
These builtins take an inout object reference and return a
boolean. Passing the reference inout forces the optimizer to preserve
a retain distinct from what’s required to maintain lifetime for any of
the reference's source-level copies, because the called function is
allowed to replace the reference, thereby releasing the referent.
Before this change, the API entry points for uniqueness checking
already took an inout reference. However, after full inlining, it was
possible for two source-level variables that reference the same object
to appear to be the same variable from the optimizer's perspective
because an address to the variable was longer taken at the point of
checking uniqueness. Consequently the optimizer could remove
"redundant" copies which were actually needed to implement
copy-on-write semantics. With a builtin, the variable whose reference
is being checked for uniqueness appears mutable at the level of an
individual SIL instruction.
The kind of reference count checking that Builtin.isUnique performs
depends on the argument type:
- Native object types are directly checked by reading the
strong reference count:
(Builtin.NativeObject, known native class reference)
- Objective-C object types require an additional check that the
dynamic object type uses native swift reference counting:
(Builtin.UnknownObject, unknown class reference, class existential)
- Bridged object types allow the dymanic object type check to be
bypassed based on the pointer encoding:
(Builtin.BridgeObject)
Any of the above types may also be wrapped in an optional. If the
static argument type is optional, then a null check is also performed.
Thus, isUnique only returns true for non-null, native swift object
references with a strong reference count of one.
isUniqueOrPinned has the same semantics as isUnique except that it
also returns true if the object is marked pinned regardless of the
reference count. This allows for simultaneous non-structural
modification of multiple subobjects.
In some cases, the standard library can dynamically determine that it
has a native reference even though the static type is a bridge or
unknown object. Unsafe variants of the builtin are available to allow
the additional pointer bit mask and dynamic class lookup to be
bypassed in these cases:
isUnique_native : <T> (inout T[?]) -> Int1
isUniqueOrPinned_native : <T> (inout T[?]) -> Int1
These builtins perform an implicit cast to NativeObject before
checking uniqueness. There’s no way at SIL level to cast the address
of a reference, so we need to encapsulate this operation as part of
the builtin.
Swift SVN r27887
reference to something of class type. This is required to model
RebindSelfInConstructorExpr correctly to DI, since in the class case,
self.init and super.init *take* a value out of class box so that it
can pass the +1 value without performing an extra retain. Nothing
else in the compiler uninitializes a DI-controlled memory object
like this, so nothing else needs this. DI really doesn't like something
going from initialized to uninitialized.
Yes, I feel super-gross about this and am really unhappy about it. I
may end up reverting this if I can find an alternate solution to this
problem.
Swift SVN r27525
This is new attribute we're using to coalesce @thin, @objc_block, and @cc, and to extend to new uses like C function pointer types. Parse the new attribute, but preserve support for the old attributes, and print with the old attributes for now to separate out test changes. Migration fixits and test updates to come. I did take the opportunity here to kill off the '@cc(cdecl)' hack for AST-level function pointer types, which are now only spelt with @convention(c).
Swift SVN r27247
Previously some parts of the compiler referred to them as "fields",
and most referred to them as "elements". Use the more generic 'elements'
nomenclature because that's what we refer to other things in the compiler
(e.g. the elements of a bracestmt).
At the same time, make the API better by providing "getElement" consistently
and using it, instead of getElements()[i].
NFC.
Swift SVN r26894
threaded into IRGen; tests to follow when that's done.
I made a preliminary effort to make the inliner do the
right thing with try_apply, but otherwise tried to avoid
touching the optimizer any more than was required by the
removal of ApplyInstBase.
Swift SVN r26747
As part of this, re-arrange the argument order so that
generic arguments come before the context, which comes
before the error result. Be more consistent about always
adding a context parameter on thick functions, even
when it's unused. Pull out the witness-method Self
argument so that it appears last after the error
argument.
Swift SVN r26667
We no longer need or use it since we can always refer to the same bit on
the applied function when deciding whether to inline during mandatory
inlining.
Resolves rdar://problem/19478366.
Swift SVN r26534
For better consistency with other address-only instruction variants, and to open the door to new exciting existential representations (such as a refcounted boxed representation for ErrorType).
Swift SVN r25902
If multiple swift files are compiled together, then guessing as to the
file when we emit IR obviously doesn't work. Find the filename when we
generate a function's coverage map and propagate it through SIL.
Swift SVN r25436
Keeping a reference to the function here is dangerous. We only
actually care about the name, so save ourselves a copy of that
instead.
This fixes a crash that seems to happen only when the coverage data is
very large.
Swift SVN r25433
Before if you had a differing number of arguments from types, you would
get the error:
Expected sil type to have the right argument types.
Now we say:
Expected sil type to have the same number of arg names as arg types.
which is slightly clearer.
Swift SVN r25049
This will have an effect on inlining into thunks.
Currently this flag is set for witness thunks and thunks from function signature optimization.
No change in code generation, yet.
Swift SVN r24998
