It converts a lazily initialized global to a statically initialized global variable.
When this pass runs on a global initializer `[global_init_once_fn]` it tries to create a static initializer for the initialized global.
```
sil [global_init_once_fn] @globalinit {
alloc_global @the_global
%a = global_addr @the_global
%i = some_const_initializer_insts
store %i to %a
}
```
The pass creates a static initializer for the global:
```
sil_global @the_global = {
%initval = some_const_initializer_insts
}
```
and removes the allocation and store instructions from the initializer function:
```
sil [global_init_once_fn] @globalinit {
%a = global_addr @the_global
%i = some_const_initializer_insts
}
```
The initializer then becomes a side-effect free function which let's the builtin-simplification remove the `builtin "once"` which calls the initializer.
Now that we handle inlined global initializers in LICM, CSE and the StringOptimization, we don't need to have a separate mid-level inliner pass, which treats global accessors specially.
A pass is skipped if no other pass changed the function since the previous run of the same pass.
Don't do this is if a pass depends on the function bodies of called functions, e.g. the inliner.
Other passes might change the callees, e.g. function signature opts, which makes it worth to run the inliner
again, even if the function itself didn't change.
Specifically, we already have the appropriate semantics for arguments captured
by escaping closures but in certain cases allocbox to stack is able to prove
that the closure doesn’t actually escape. This results in the capture being
converted into a non-escaping SIL form. This then causes the move checker to
emit the wrong kind of error.
The solution is to create an early allocbox to stack that doesn’t promote move
only types in boxes from heap -> stack if it is captured by an escaping closure
but does everything else normally. Then once the move checking is completed, we
run alloc box to stack an additional time to ensure that we keep the guarantee
that heap -> stack is performed in those cases.
rdar://108905586
Optimizations can rely on alias analysis to know that an in-argument (or parts of it) is not actually read.
We have to do the same in the verifier: if alias analysis says that an in-argument is not read, there is no need that the memory location is initialized.
Fixes a false verifier error.
rdar://106806899
to work with aggregates containing unknown values. Such aggregates
can be generated when an instruction is skipped during constant
evaluation and its results are used to create a struct.
Linear maps are captured in vjp routine via callee-guaranteed partial apply and are passed as @owned references to the enclosing pullback that finally consumes them. Necessary retains are inserted by a partial apply forwarder.
However, this is not the case when the function being differentiated contains loops as heap-allocated context is used and bare pointer is captured by the pullback partial apply. As a result, partial apply forwarder does not retain the linear maps that are owned by a heap-allocated context, however, they are still treated as @owned references and therefore are released in the pullback after the first call. As a result, subsequent pullback calls release linear maps and we'd end with possible use-after-free.
Ensure we retain values when we load values from the context.
Reproducible only when:
* Loops (so, heap-allocated context)
* Pullbacks of thick functions (so context is non-zero)
* Multiple pullback calls
* Some cleanup while there
Fixes#64257
Previously, the utility bailed out on lexical lifetimes because it
didn't respect deinit barriers. Here, deinit barriers are found and
added to liveness if the value is lexical. This enables copies to be
propagated without hoisting destroys over deinit barriers.
rdar://104630103
Use BasicBlockBitfield to record per-block liveness state. This has
been the intention since BasicBlockBitfield was first introduced.
Remove the per-field bitfield from PrunedLiveBlocks. This
(re)specializes the data structure for scalar liveness and drastically
simplifies the implementation.
This utility is fundamental to all ownership utilities. It will be on
the critical path in many areas of the compiler, including at
-Onone. It needs to be minimal and as easy as possible for compiler
engineers to understand, investigate, and debug.
This is in preparation for fixing bugs related to multi-def liveness
as used by the move checker.
Add a separate 'verifyOwnership()' entry point so it's possible
to check OSSA lifetimes at various points.
Move SILGenCleanup into a SILGen pass pipeline.
After SILGen, verify incomplete OSSA.
After SILGenCleanup, verify ownership.
The `isEscaping` function is called a lot from ARCSequenceOpt and ReleaseHoisting.
To avoid quadratic complexity for large functions, limit the amount of work what the EscapeUtils are allowed to to.
This keeps the complexity linear.
The arbitrary limit is good enough for almost all functions.
It lets the EscapeUtils do several hundred up/down walks which is much more than needed in most cases.
Fixes a compiler hang
https://github.com/apple/swift/issues/63846
rdar://105795976
Otherwise, sometimes when the object checker emits a diagnostic and cleans up
the IR, some of the cleaned up copies are copies that should have been handled
by the address checker. The end result is that the address checker does not emit
diagnostics for that IR. I found this problem was exascerbated when writing code
for escaping closures.
This commit also cleans up the passes in preparation for at a future time moving
some of the transformations into the utils folder.
Although nonescaping closures are representationally trivial pointers to their
on-stack context, it is useful to model them as borrowing their captures, which
allows for checking correct use of move-only values across the closure, and
lets us model the lifetime dependence between a closure and its captures without
an ad-hoc web of `mark_dependence` instructions.
During ownership elimination, We eliminate copy/destroy_value instructions and
end the partial_apply's lifetime with an explicit dealloc_stack as before,
for compatibility with existing IRGen and non-OSSA aware passes.
Encapsulate all the complexity of reborrows and guaranteed phi in 3
ownership liveness interfaces:
LinerLiveness, InteriorLiveness, and ExtendedLiveness.
The Swift Simplification pass can do more than the old MandatoryCombine pass: simplification of more instruction types and dead code elimination.
The result is a better -Onone performance while still keeping debug info consistent.
Currently following code patterns are simplified:
* `struct` -> `struct_extract`
* `enum` -> `unchecked_enum_data`
* `partial_apply` -> `apply`
* `br` to a 1:1 related block
* `cond_br` with a constant condition
* `isConcrete` and `is_same_metadata` builtins
More simplifications can be added in the future.
rdar://96708429
rdar://104562580
If a `debug_step` has the same debug location as a previous or succeeding instruction it is removed.
It's just important that there is at least one instruction for a certain debug location so that single stepping on that location will work.
The changes are intentionally were made close to the original implementation w/o possible simplifications to ease the review
Fixes#63207, supersedes #63379 (and fixes#63234)
Specifically, previously if we emitted an error we just dumped all of the
consuming uses. Now instead for each consuming use that needs a copy, we perform
a search for a specific boundary use (consuming or non-consuming) that is
reachable from the former and emit a specialized error for it. Thus we emit for
the two consuming case the normal consumed twice error, and now for
non-consuming errors we emit the "use after consume" error.
