An object with tail allocated elements is in risk of being passed to malloc_size, which does not work for non-heap allocated objects.
Conservatively, disable objects with tail allocations.
rdar://121886093
Usually resilient classes cannot be promoted anyway, because their initializers are not visible and let the object appear to escape.
But in some rare situations this check is needed.
rdar://121558570
Add a new mandatory BooleanLiteralFolding pass which constant folds conditional branches with boolean literals as operands.
```
%1 = integer_literal -1
%2 = apply %bool_init(%1) // Bool.init(_builtinBooleanLiteral:)
%3 = struct_extract %2, #Bool._value
cond_br %3, bb1, bb2
```
->
```
...
br bb1
```
This pass is intended to run before DefiniteInitialization, where mandatory inlining and constant folding didn't run, yet (which would perform this kind of optimization).
This optimization is required to let DefiniteInitialization handle boolean literals correctly.
For example in infinite loops:
```
init() {
while true { // DI need to know that there is no loop exit from this while-statement
if some_condition {
member_field = init_value
break
}
}
}
```
```
let c = SomeClass()
```
is turned into
```
private let outlinedVariable = SomeClass() // statically initialized and allocated in the data section
let c = outlinedVariable
```
rdar://111021230
rdar://115502043
Also, make the ObjectOutliner work for OSSA. Though, it currently doesn't run in the OSSA pipeline.
Optionally, the dependency to the initialization of the global can be specified with a dependency token `depends_on <token>`.
This is usually a `builtin "once"` which calls the initializer for the global variable.
Layers:
- FunctionConvention: AST FunctionType: results, parameters
- ArgumentConventions: SIL function arguments
- ApplyOperandConventions: applied operands
The meaning of an integer index is determined by the collection
type. All the mapping between the various indices (results,
parameters, SIL argument, applied arguments) is restricted to the
collection type that owns that mapping. Remove the concept of a
"caller argument index".
By default it lowers the builtin to an `alloc_vector` with a paired `dealloc_stack`.
If the builtin appears in the initializer of a global variable and the vector elements are initialized,
a statically initialized global is created where the initializer is a `vector` instruction.
In regular swift this is a nice optimization. In embedded swift it's a requirement, because the compiler needs to be able to specialize generic deinits of non-copyable types.
The new de-virtualization utilities are called from two places:
* from the new DeinitDevirtualizer pass. It replaces the old MoveOnlyDeinitDevirtualization, which is very basic and does not fulfill the needs for embedded swift.
* from MandatoryPerformanceOptimizations for embedded swift
* add `NominalTypeDecl.isResilient`
* make the return type of `Type.getNominalFields` optional and return nil in case the nominal type is resilient.
This forces users of this API to think about what to do in case the nominal type is resilient.
A transformation must not create a `struct` instruction with a non-copyable type because this would apply that a (potential) deinit would be called for that struct.
Make filter APIs for UseList chainable by adding them to Sequence where Element == Operand
For example, it allows to write:
```
let singleUse = value.uses.ignoreDebugUses.ignoreUsers(ofType: EndAccessInst.self).singleUse
```
Also, add `UseList.getSingleUser(notOfType:)`
When merging stores in a global initializer, it's possible that the merged store is inserted at the wrong location, causing a SIL verifier error.
This is hard to reproduce, but can happen.
The merged store must be inserted _after_ all other stores. Instead it's inserted after the store of the last property. Now, if properties are _not_ initialized in the order they are declared, this problem can show up.
rdar://117189962
Introduce two modes of bridging:
* inline mode: this is basically how it worked so far. Using full C++ interop which allows bridging functions to be inlined.
* pure mode: bridging functions are not inlined but compiled in a cpp file. This allows to reduce the C++ interop requirements to a minimum. No std/llvm/swift headers are imported.
This change requires a major refactoring of bridging sources. The implementation of bridging functions go to two separate files: SILBridgingImpl.h and OptimizerBridgingImpl.h.
Depending on the mode, those files are either included in the corresponding header files (inline mode), or included in the c++ file (pure mode).
The mode can be selected with the BRIDGING_MODE cmake variable. By default it is set to the inline mode (= existing behavior). The pure mode is only selected in certain configurations to work around C++ interop issues:
* In debug builds, to workaround a problem with LLDB's `po` command (rdar://115770255).
* On windows to workaround a build problem.
All SILArgument types are "block arguments". There are three kinds:
1. Function arguments
2. Phis
3. Terminator results
In every situation where the source of the block argument matters, we
need to distinguish between these three. Accidentally failing to
handle one of the cases is an perpetual source of compiler
bugs. Attempting to handle both phis and terminator results uniformly
is *always* a bug, especially once OSSA has phi flags. Even when all
cases are handled correctly, the code that deals with data flow across
blocks is incomprehensible without giving each case a type. This
continues to be a massive waste of time literally every time I review
code that involves cross-block control flow.
Unfortunately, we don't have these C++ types yet (nothing big is
blocking that, it just wasn't done). That's manageable because we can
use wrapper types on the Swift side for now. Wrapper types don't
create any more complexity than protocols, but they do sacrifice some
usability in switch cases.
There is no reason for a BlockArgument type. First, a function
argument is a block argument just as much as any other. BlockArgument
provides no useful information beyond Argument. And it is nearly
always a mistake to care about whether a value is a function argument
and not care whether it is a phi or terminator result.
For chains of async functions where suspensions can be statically
proven to never be required, this pass removes all suspensions and
turns the functions into synchronous functions.
For example, this function does not actually require any suspensions,
once the correct executor is acquired upon initial entry:
```
func fib(_ n: Int) async -> Int {
if n <= 1 { return n }
return await fib(n-1) + fib(n-2)
}
```
So we can turn the above into this for better performance:
```
func fib() async -> Int {
return fib_sync()
}
func fib_sync(_ n: Int) -> Int {
if n <= 1 { return n }
return fib(n-1) + fib(n-2)
}
```
while rewriting callers of `fib` to use the `sync` entry-point
when we can prove that it will be invoked on a compatible executor.
This pass is currently experimental and under development. Thus, it
is disabled by default and you must use
`-enable-experimental-async-demotion` to try it.
It lowers let property accesses of classes.
Lowering consists of two tasks:
* In class initializers, insert `end_init_let_ref` instructions at places where all let-fields are initialized.
This strictly separates the life-range of the class into a region where let fields are still written during
initialization and a region where let fields are truly immutable.
* Add the `[immutable]` flag to all `ref_element_addr` instructions (for let-fields) which are in the "immutable"
region. This includes the region after an inserted `end_init_let_ref` in an class initializer, but also all
let-field accesses in other functions than the initializer and the destructor.
This pass should run after DefiniteInitialization but before RawSILInstLowering (because it relies on `mark_uninitialized` still present in the class initializer).
Note that it's not mandatory to run this pass. If it doesn't run, SIL is still correct.
Simplified example (after lowering):
bb0(%0 : @owned C): // = self of the class initializer
%1 = mark_uninitialized %0
%2 = ref_element_addr %1, #C.l // a let-field
store %init_value to %2
%3 = end_init_let_ref %1 // inserted by lowering
%4 = ref_element_addr [immutable] %3, #C.l // set to immutable by lowering
%5 = load %4
This instructions marks the point where all let-fields of a class are initialized.
This is important to ensure the correctness of ``ref_element_addr [immutable]`` for let-fields,
because in the initializer of a class, its let-fields are not immutable, yet.
Codegen is the same, but `begin_dealloc_ref` consumes the operand and produces a new SSA value.
This cleanly splits the liferange to the region before and within the destructor of a class.
