In order to transfer debug info from `debug_value` to `alloc_stack` we need to drop `op_ref` debug expression, as the latter instruction represents the location and not the value itself. Also, fix the debug info verifier as variable type was deduced from `alloc_stack` / `alloc_box` improperly: pointer type of instruction itself was used instead of underlying object type.
The issue is only exposed when both optimizations (SIL mem2reg at least) and debug info are enabled
Resolves SR-15849
Added an AST helper in Types.h:
- isPotentiallyAnyObject()
This formalizes logic for when cast operations forward
ownership. Various OSSA optimization rely on this for
correctness. This fixes latent bugs throughout the optimizer.
I was compelled to fix this now because we want to make OSSA
optimizations across dynamic casts more aggressive. For example, we
want to optimize retain/release across enum formation.
The main point of this change is to make sure that a shared function always has a body: both, in the optimizer pipeline and in the swiftmodule file.
This is important because the compiler always needs to emit code for a shared function. Shared functions cannot be referenced from outside the module.
In several corner cases we missed to maintain this invariant which resulted in unresolved-symbol linker errors.
As side-effect of this change we can drop the shared_external SIL linkage and the IsSerializable flag, which simplifies the serialization and linkage concept.
This ensures that opened archetypes always inherit any outer generic parameters from the context in which they reside. This matters because class bounds may bind generic parameters from these outer contexts, and without the outer context you can wind up with ill-formed generic environments like
<τ_0_0, where τ_0_0 : C<T>, τ_0_0 : P>
Where T is otherwise unbound because there is no entry for it among the generic parameters of the environment's associated generic signature.
This is just a quick fix to stop us from dropping live values such as m in the
following example:
```
public func addressOnlyVarTest<T : P>(_ x: T) {
var k = x
k.doSomething()
let m = _move(k)
m.doSomething()
k = x
k.doSomething()
}
```
Before this change, we would just drop m and one wouldn't even see it in the
debugger.
I am only doing this currently for cases where when we merge at least one
alloc_stack was moved. The reason why is that to implement this correctly, I
need to use llvm.dbg.addr and changing the debug info from using
llvm.dbg.declare -> llvm.dbg.addr requires statistics and needs to be done a
little later in the swift development process. If one of these alloc_stack had
the [moved] marker attached to it, we know the user /did/ use move so they have
in a sense opted into having a move function effect its program so we are only
changing how new code appears in the debugger.
This subclass of SILArgument should be eliminated--it's not always a
phi, and whether it is a "phi argument" has nothing whatsoever to do
with the opcode. That is a property of a value's uses, not a property of the
value.
Until then, provide a logical and useful API within the type. This
often avoids the need to explicitly cast to a SILPhiArgument type and
avoids a lot of boilerplate in code that deals with phis.
Note: PhiOperand and PhiValue are improved abstractions on top of this
API. But the SILArgument-level API is still an important bridge
between SILArgument and other phi abstractions.
A serialized specialized function can reference another specialized function.
In case the other specialization is already generated by the optimizer before the de-serialization point,
we can end up that a shared_external function references a shared function. This is okay.
This is an instruction that I am going to use to drive some of the ownership
based dataflow optimizations that I am writing now. The instruction contains a
kind that allows one to know what type of checking is required and allows the
need to add a bunch of independent instructions for independent checkers. Each
checker is responsible for removing all of its own mark instructions. NOTE:
MarkMustCheckInst is only allowed in Raw SIL since once we are in Canonical SIL
we want to ensure that all such checking has already occurred.
Squashed commit of the following:
commit e5a05ffe44
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 27 17:45:31 2022 +0900
cleanup
commit 1f751cea5a
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 27 14:50:33 2022 +0900
cleanups
commit c632f3215d
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 27 14:01:09 2022 +0900
add test for generic from actor decl
commit 09b8bd50a7
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 27 14:00:58 2022 +0900
cleanups
commit 31f4d0cffd
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 27 11:40:51 2022 +0900
fix test
commit ad4db2fb6c
Merge: 97227edcca07e2dfda56
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 26 23:31:41 2022 +0900
Merge branch 'main' into wip-zzz
commit 97227edcca
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 26 21:01:25 2022 +0900
remove @_dynamic methods!
fix tests
commit 1c79344dbb
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 19 12:51:09 2022 +0900
cleanup
wip
stuck
fixed the stack cleanups
cleanups pretty good now
weird load
rki
works
remove hack
add take + throw + return
fix test
more tests fixed
more tests fixed
more tests fixed
commit 3ed494c175
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Tue Jan 18 21:09:28 2022 +0900
stack issues in SIL verification
commit 5cf43a7f86
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Tue Jan 18 09:19:51 2022 +0900
about to call the remoteCall
goot to return, but missing subs
commit df8e47122a
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 13 14:09:49 2022 +0900
[Distributed] Refactor Invocation to Decoder/Encoder
getting there
done-recording
working on the string init
stuck trying to get String initializer SILFunction
created the remote call target
commit fc7bd62f32
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 12 23:01:14 2022 +0900
[Distributed] Pass arguments from Invocation to HBuffer
commit cafc2cc058
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 12 22:08:47 2022 +0900
works
commit a7d01837ff
Author: Pavel Yaskevich <pyaskevich@apple.com>
Date: Tue Jan 11 15:48:58 2022 -0800
[Distributed] Adjust interface of `swift_distributed_execute_target`
Since this is a special function, `calleeContext` doesn't point to
a direct parent but instead both parent context (uninitialized)
and resume function are passed as last arguments which means that
`callContext` has to act as an intermediate context in call to accessor.
commit c1f830be27
Author: Pavel Yaskevich <pyaskevich@apple.com>
Date: Tue Jan 11 17:00:08 2022 -0800
[Distributed] Drop optionality from result buffer in `_executeDistributedTarget`
`RawPointer?` is lowered into a two arguments since it's a struct,
to make it easy let's just allocate an empty pointer for `Void` result.
commit c83c2c37b6
Author: Pavel Yaskevich <pyaskevich@apple.com>
Date: Tue Jan 11 17:02:45 2022 -0800
[Distributed] NFC: Update _remoteCall test-case to check multiple different result types
commit 29e7cf50e4
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 12 21:32:37 2022 +0900
wip
commit 9128ecc6f8
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 12 20:46:20 2022 +0900
wip
commit a6b2a62a67
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 12 20:38:22 2022 +0900
wip
commit 8b188f0d43
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 12 16:55:10 2022 +0900
wip
commit 3796bec2b9
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Jan 12 16:55:02 2022 +0900
wip
commit 0ffc68b5ef
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Tue Jan 11 21:44:58 2022 +0900
[Distributed] Implementing ad-hoc protocol requirements
commit 78862575e4
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 6 18:03:54 2022 +0900
cleanup
commit 5f4ab89e25
Merge: 24a628e7c0fdda6f2ee4
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 6 15:51:39 2022 +0900
Merge branch 'main' into wip-impl-execute-swift
commit 24a628e7c0
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Thu Jan 6 15:33:21 2022 +0900
wip
commit 69e7fed09d
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Dec 22 06:36:45 2021 +0900
[Distributed] comment out distributed_actor_remoteCall for now
commit 376733a9f6
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Tue Dec 21 16:00:06 2021 +0900
reimplement distributed get type info impls
commit 74ab47886a
Author: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Wed Dec 15 21:37:08 2021 +0900
[Distributed] Implement func metadata and executeDistributedTarget
dont expose new entrypoints
able to get all the way to calling _execute
Introduce a new instruction `dealloc_stack_ref ` and remove the `stack` flag from `dealloc_ref`.
The `dealloc_ref [stack]` was confusing, because all it does is to mark the deallocation of the stack space for a stack promoted object.
This instruction is similar to a copy_addr except that it marks a move of an
address that has to be checked. In order to keep the memory lifetime verifier
happy, the semantics before the checker runs are the mark_unresolved_move_addr is
equivalent to copy_addr [init] (not copy_addr [take][init]).
The use of this instruction is that Mandatory Inlining converts builtin "move"
to a mark_unresolved_move_addr when inlining the function "_move" (the only
place said builtin is invoked).
This is then run through a special checker (that is later in this PR) that
either proves that the mark_unresolved_move_addr can actually be a move in which
case it converts it to copy_addr [take][init] or if it can not be a move, emit
an error and convert the instruction to a copy_addr [init]. After this is done
for all instructions, we loop back through again and emit an error on any
mark_unresolved_move_addr that were not processed earlier allowing for us to
know that we have completeness.
NOTE: The move kills checker for addresses is going to run after Mandatory
Inlining, but before predictable memory opts and friends.
The reason why I am doing this is that currently checked_cast_br of an AnyObject
may return a different value due to boxing. As an example, this can occur when
performing a checked_cast_br of a __SwiftValue(AnyHashable(Klass())).
To model this in SIL, I added to OwnershipForwardingMixin a bit of information
that states if the instruction directly forwards ownership with a default value
of true. In checked_cast_br's constructor though I specialize this behavior if
the source type is AnyObject and thus mark the checked_cast_br as not directly
forwarding its operand. If an OwnershipForwardingMixin directly forwards
ownership, one can assume that if it forwards ownership, it will always do so in
a way that ensures that each forwarded value is rc-identical to whatever result
it algebraically forwards ownership to. So in the context of checked_cast_br, it
means that the source value is rc-identical to the argument of the success and
default blocks.
I added a verifier check to CheckedCastBr that makes sure that it can never
forward guaranteed ownership and have a source type of AnyObject.
In SemanticARCOpts, I modified the code that builds extended live ranges of
owned values (*) to check if a OwnershipForwardingMixin is directly
forwarding. If it is not directly forwarding, then we treat the use just as an
unknown consuming use. This will then prevent us from converting such an owned
value to guaranteed appropriately in such a case.
I also in SILGen needed to change checked_cast_br emission in SILGenBuilder to
perform an ensurePlusOne on the input operand (converting it to +1 with an
appropriate cleanup) if the source type is an AnyObject. I found this via the
verifier check catching this behavior from SILGen when compiling libswift. This
just shows how important IR verification of invariants can be.
(*) For those unaware, SemanticARCOpts contains a model of an owned value and
all forwarding uses of it called an OwnershipLiveRange.
rdar://85710101
Required for UnsafeRawPointer.withMemoryReboud(to:).
%out_token = rebind_memory %0 : $Builtin.RawPointer to %in_token
%0 must be of $Builtin.RawPointer type
%in_token represents a cached set of bound types from a prior memory state.
%out_token is an opaque $Builtin.Word representing the previously bound
types for this memory region.
This instruction's semantics are identical to ``bind_memory``, except
that the types to which memory will be bound, and the extent of the
memory region is unknown at compile time. Instead, the bound-types are
represented by a token that was produced by a prior memory binding
operation. ``%in_token`` must be the result of bind_memory or
The key thing is that the move checker will not consider the explicit copy value
to be a copy_value that can be rewritten, ensuring that any uses of the result
of the explicit copy_value (consuming or other wise) are not checked.
Similar to the _move operator I recently introduced, this is a transparent
function so we can perform one level of specialization and thus at least be
generic over all concrete types.
This patch introduces a new stdlib function called _move:
```Swift
@_alwaysEmitIntoClient
@_transparent
@_semantics("lifetimemanagement.move")
public func _move<T>(_ value: __owned T) -> T {
#if $ExperimentalMoveOnly
Builtin.move(value)
#else
value
#endif
}
```
It is a first attempt at creating a "move" function for Swift, albeit a skleton
one since we do not yet perform the "no use after move" analysis. But this at
leasts gets the skeleton into place so we can built the analysis on top of it
and churn tree in a manageable way. Thus in its current incarnation, all it does
is take in an __owned +1 parameter and returns it after moving it through
Builtin.move.
Given that we want to use an OSSA based analysis for our "no use after move"
analysis and we do not have opaque values yet, we can not supporting moving
generic values since they are address only. This has stymied us in the past from
creating this function. With the implementation in this PR via a bit of
cleverness, we are now able to support this as a generic function over all
concrete types by being a little clever.
The trick is that when we transparent inline _move (to get the builtin), we
perform one level of specialization causing the inlined Builtin.move to be of a
loadable type. If after transparent inlining, we inline builtin "move" into a
context where it is still address only, we emit a diagnostic telling the user
that they applied move to a generic or existential and that this is not yet
supported.
The reason why we are taking this approach is that we wish to use this to
implement a new (as yet unwritten) diagnostic pass that verifies that _move
(even for non-trivial copyable values) ends the lifetime of the value. This will
ensure that one can write the following code to reliably end the lifetime of a
let binding in Swift:
```Swift
let x = Klass()
let _ = _move(x)
// hypotheticalUse(x)
```
Without the diagnostic pass, if one were to write another hypothetical use of x
after the _move, the compiler would copy x to at least hypotheticalUse(x)
meaning the lifetime of x would not end at the _move, =><=.
So to implement this diagnostic pass, we want to use the OSSA infrastructure and
that only works on objects! So how do we square this circle: by taking advantage
of the mandatory SIL optimzier pipeline! Specifically we take advantage of the
following:
1. Mandatory Inlining and Predictable Dead Allocation Elimination run before any
of the move only diagnostic passes that we run.
2. Mandatory Inlining is able to specialize a callee a single level when it
inlines code. One can take advantage of this to even at -Onone to
monomorphosize code.
and then note that _move is such a simple function that predictable dead
allocation elimination is able to without issue eliminate the extra alloc_stack
that appear in the caller after inlining without issue. So we (as the tests
show) get SIL that for concrete types looks exactly like we just had run a
move_value for that specific type as an object since we promote away the
stores/loads in favor of object operations when we eliminate the allocation.
In order to prevent any issue with this being used in a context where multiple
specializations may occur, I made the inliner emit a diagnostic if it inlines
_move into a function that applies it to an address only value. The diagnostic
is emitted at the source location where the function call occurs so it is easy
to find, e.x.:
```
func addressOnlyMove<T>(t: T) -> T {
_move(t) // expected-error {{move() used on a generic or existential value}}
}
moveonly_builtin_generic_failure.swift:12:5: error: move() used on a generic or existential value
_move(t)
^
```
To eliminate any potential ABI impact, if someone calls _move in a way that
causes it to be used in a context where the transparent inliner will not inline
it, I taught IRGen that Builtin.move is equivalent to a take from src -> dst and
marked _move as always emit into client (AEIC). I also took advantage of the
feature flag I added in the previous commit in order to prevent any cond_fails
from exposing Builtin.move in the stdlib. If one does not pass in the flag
-enable-experimental-move-only then the function just returns the value without
calling Builtin.move, so we are safe.
rdar://83957028
Adds two new IRGen-level builtins (one for allocating, the other for deallocating), a stdlib shim function for enhanced stack-promotion heuristics, and the proposed public stdlib functions.
