Strict aliasing only applies to memory operations that use strict
addresses. The optimizer needs to be aware of this flag. Uses of raw
addresses should not have their address substituted with a strict
address.
Also add Builtin.LoadRaw which will be used by raw pointer loads.
Till now there was no way in SIL to explicitly express a dependency of an instruction on any opened archetypes used by it. This was a cause of many errors and correctness issues. In many cases the code was moved around without taking into account these dependencies, which resulted in breaking the invariant that any uses of an opened archetype should be dominated by the definition of this archetype.
This patch does the following:
- Map opened archetypes to the instructions defining them, i.e. to open_existential instructions.
- Introduce a helper class SILOpenedArchetypesTracker for creating and maintaining such mappings.
- Introduce a helper class SILOpenedArchetypesState for providing a read-only API for looking up available opened archetypes.
- Each SIL instruction which uses an opened archetype as a type gets an additional opened archetype operand representing a dependency of the instruction on this archetype. These opened archetypes operands are an in-memory representation. They are not serialized. Instead, they are re-constructed when reading binary or textual SIL files.
- SILVerifier was extended to conduct more thorough checks related to the usage of opened archetypes.
Till now there was no way in SIL to explicitly express a dependency of an instruction on any opened archetypes used by it. This was a cause of many errors and correctness issues. In many cases the code was moved around without taking into account these dependencies, which resulted in breaking the invariant that any uses of an opened archetype should be dominated by the definition of this archetype.
This patch does the following:
- Map opened archetypes to the instructions defining them, i.e. to open_existential instructions.
- Introduce a helper class SILOpenedArchetypesTracker for creating and maintaining such mappings.
- Introduce a helper class SILOpenedArchetypesState for providing a read-only API for looking up available opened archetypes.
- Each SIL instruction which uses an opened archetype as a type gets an additional opened archetype operand representing a dependency of the instruction on this archetype. These opened archetypes operands are an in-memory representation. They are not serialized. Instead, they are re-constructed when reading binary or textual SIL files.
- SILVerifier was extended to conduct more thorough checks related to the usage of opened archetypes.
Till now there was no way in SIL to explicitly express a dependency of an instruction on any opened archetypes used by it. This was a cause of many errors and correctness issues. In many cases the code was moved around without taking into account these dependencies, which resulted in breaking the invariant that any uses of an opened archetype should be dominated by the definition of this archetype.
This patch does the following:
- Map opened archetypes to the instructions defining them, i.e. to open_existential instructions.
- Introduce a helper class SILOpenedArchetypesTracker for creating and maintaining such mappings.
- Introduce a helper class SILOpenedArchetypesState for providing a read-only API for looking up available opened archetypes.
- Each SIL instruction which uses an opened archetype as a type gets an additional opened archetype operand representing a dependency of the instruction on this archetype. These opened archetypes operands are an in-memory representation. They are not serialized. Instead, they are re-constructed when reading binary or textual SIL files.
- SILVerifier was extended to conduct more thorough checks related to the usage of opened archetypes.
Now that ObjC types can be generic, we need to satisfy the type system by plumbing pseudogeneric parameters through func-to-block invocation thunks. Fixes rdar://problem/26524763.
This instruction creates a "virtual" address to represent a property with a behavior that supports definite initialization. The instruction holds references to functions that perform the initialization and 'set' logic for the property. It will be DI's job to rewrite assignments into this virtual address into calls to the initializer or setter based on the initialization state of the property at the time of assignment.
As there are no instructions left which produce multiple result values, this is a NFC regarding the generated SIL and generated code.
Although this commit is large, most changes are straightforward adoptions to the changes in the ValueBase and SILValue classes.
And use the new project_existential_box to get to the address value.
SILGen now generates a project_existential_box for each alloc_existential_box.
And IRGen re-uses the address value from the alloc_existential_box if the operand of project_existential_box is an alloc_existential_box.
This lets the generated code be the same as before.
This eliminates some minor overheads, but mostly it eliminates
a lot of conceptual complexity due to the overhead basically
appearing outside of its context.
The main idea here is that we really, really want to be
able to recover the protocol requirement of a conformance
reference even if it's abstract due to the conforming type
being abstract (e.g. an archetype). I've made the conversion
from ProtocolConformance* explicit to discourage casual
contamination of the Ref with a null value.
As part of this change, always make conformance arrays in
Substitutions fully parallel to the requirements, as opposed
to occasionally being empty when the conformances are abstract.
As another part of this, I've tried to proactively fix
prospective bugs with partially-concrete conformances, which I
believe can happen with concretely-bound archetypes.
In addition to just giving us stronger invariants, this is
progress towards the removal of the archetype from Substitution.
If a global variable in a module we are compiling has a type containing
a resilient value type from a different module, we don't know the size
at compile time, so we cannot allocate storage for the global statically.
Instead, we will use a buffer, just like alloc_stack does for archetypes
and resilient value types.
This adds a new SIL instruction but does not yet make use of it.
Debug variable info may be attached to debug_value, debug_value_addr,
alloc_box, and alloc_stack instructions.
In order to write textual SIL -> SIL testcases that exercise the handling
of debug information by SIL passes, we need to make a couple of additions
to the textual SIL language. In memory, the debug information attached to
SIL instructions references information from the AST. If we want to create
debug info from parsing a textual .sil file, these bits need to be made
explicit.
Performance Notes: This is memory neutral for compilations from Swift
source code, because the variable name is still stored in the AST. For
compilations from textual source the variable name is stored in tail-
allocated memory following the SIL instruction that introduces the
variable.
<rdar://problem/22707128>
(libraries now)
It has been generally agreed that we need to do this reorg, and now
seems like the perfect time. Some major pass reorganization is in the
works.
This does not have to be the final word on the matter. The consensus
among those working on the code is that it's much better than what we
had and a better starting point for future bike shedding.
Note that the previous organization was designed to allow separate
analysis and optimization libraries. It turns out this is an
artificial distinction and not an important goal.
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 commit adds a DebugVariable field that is shared by
- AllocBoxInst
- AllocStackInst
- DebugValueInst
- DebugValueAddrInst
Currently DebugVariable only holds the Swift argument number.
This allows us to retire several expensive heuristics in IRGen that
attempted to identify which local variables actually where arguments
and recover their relative order.
Memory footprint notes:
This commit adds a 4-byte field to 4 SILInstructin subclasses.
This was offset by 8ab1e2dd50
which removed 20 bytes from *every* SILInstruction.
Caveats:
This commit surfaces a known bug in FunctionSigantureOpts, tracked in
rdar://problem/23727705 — debug info for exploded function arguments
cannot be expressed until this is fixed.
This reapplies ed2b16dc5a with a bugfix for
generic function arrguments and an additional testcase.
<rdar://problem/21185379&22705926>
This commit adds a DebugVariable field that is shared by
- AllocBoxInst
- AllocStackInst
- DebugValueInst
- DebugValueAddrInst
Currently DebugVariable only holds the Swift argument number.
This allows us to retire several expensive heuristics in IRGen that
attempted to identify which local variables actually where arguments
and recover their relative order.
Memory footprint notes:
This commit adds a 4-byte field to 4 SILInstructin subclasses.
This was offset by 8ab1e2dd50
which removed 20 bytes from *every* SILInstruction.
Caveats:
This commit surfaces a known bug in FunctionSigantureOpts, tracked in
rdar://problem/23727705 — debug info for exploded function arguments
cannot be expressed until this is fixed.
<rdar://problem/21185379&22705926>
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
This will be used in call graph construction so that we can model calls
to deinits that are potentially called as a result of executing
instructions that can end up releasing memory.
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
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
