Dario Rexin 3cf40ea504 [IRGen] Re-introduce TypeLayout strings (#62059) ...

* Introduce TypeLayout Strings

Layout strings encode the structure of a type into a byte string that can be
interpreted by a runtime function to achieve a destroy or copy. Rather than
generating ir for a destroy/assignWithCopy/etc, we instead generate a layout
string which encodes enough information for a called runtime function to
perform the operation for us. Value witness functions tend to be quite large,
so this allows us to replace them with a single call instead. This gives us the
option of making a codesize/runtime cost trade off.

* Added Attribute @_GenerateLayoutBytecode

This marks a type definition that should use generic bytecode based
value witnesses rather than generating the standard suite of
value witness functions. This should reduce the codesize of the binary
for a runtime interpretation of the bytecode cost.

* Statically link in implementation

Summary:
This creates a library to store the runtime functions in to deploy to
runtimes that do not implement bytecode layouts. Right now, that is
everything. Once these are added to the runtime itself, it can be used
to deploy to old runtimes.

* Implement Destroy at Runtime Using LayoutStrings

If GenerateLayoutBytecode is enabled, Create a layout string and use it
to call swift_generic_destroy

* Add Resilient type and Archetype Support for BytecodeLayouts

Add Resilient type and Archetype Support to Bytecode Layouts

* Implement Bytecode assign/init with copy/take

Implements swift_generic_initialize and swift_generic_assign to allow copying
types using bytecode based witnesses.

* Add EnumTag Support

* Add IRGen Bytecode Layouts Test

Added a test to ensure layouts are correct and getting generated

* Implement BytecodeLayouts ObjC retain/release

* Fix for Non static alignments in aligned groups

* Disable MultiEnums

MultiEnums currently have some correctness issues with non fixed multienum
types. Disabling them for now then going to attempt a correct implementation in
a follow up patch

* Fixes after merge

* More fixes

* Possible fix for native unowned

* Use TypeInfoeBasedTypeLayoutEntry for all scalars when ForceStructTypeLayouts is disabled

* Remove @_GenerateBytecodeLayout attribute

* Fix typelayout_based_value_witness.swift

Co-authored-by: Gwen Mittertreiner <gwenm@fb.com>
Co-authored-by: Gwen Mittertreiner <gwen.mittertreiner@gmail.com>

2022-11-29 21:05:22 -08:00

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