Also repaint the "existential" bikeshed since there's a loud preference for talking about existentials as existentials within the implementation.
Swift SVN r3523
Describe a `ref_element_addr` instruction for extracting elements from reference types and a `generalize` instruction for representation conversion of generic values.
Swift SVN r3432
Derives the address of a member from the address of a fragile value type. SIL extract : SIL element_addr :: LLVM extractvalue : LLVM getelementptr. Also add SILVerifier checks for ExtractInst and ElementAddrInst that they deal only in values and addresses, respectively.
Swift SVN r3391
We'll need some additional instructions to describe initialization of existentials and existential method calls: `alloc_existential` to initialize an existential's witness and substitution table(s) and provide access to its storage, and `existential_method_ref`/`project_existential` to obtain a method handle from an existential and the opaque reference to hand down to the method.
Swift SVN r3348
After discussion with John, we decided that we need to be able to deallocate a partially-initialized box during initializer execution, in case an initializer expression ends up unwinding before a value is fully initialized. When optimizing reference type allocations, it would also better to expose the destructor call and release operations directly instead of hiding them inside an instruction.
Swift SVN r3291
Value types should not require destruction beyond `release`-ing their reference type members. `release` for reference types and `destroy_addr` for address-only types should cover all cleanup needs.
Swift SVN r3264
- Tighten up terminology, for instance, define what a "box" actually is
- Describe how operands can have zero, one, or many values
- Describe that only %operands are valid operands and loading constants, ints, and other literals requires distinct insns
- Make releasing a reftype and destroying a value distinct
- Describe how stack allocation of boxes and reftypes work
- Name address-only type operations `destroy_addr` and `copy_addr` to avoid confusion with rvalue operations
- Describe the full set of aggregate manipulation functions
- Clean up instruction notation to avoid ambiguities
- Throw in notes about things we need to design at some point
Swift SVN r3211
