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Author SHA1 Message Date
Ralf Jung
e023590de4 make no-variant types a dedicated Variants variant 2024-12-18 11:01:54 +01:00
Ralf Jung
21de42bf8d Variants::Single: do not use invalid VariantIdx for uninhabited enums 2024-12-18 11:00:21 +01:00
Ralf Jung
ce95a44db6 improve TagEncoding::Niche docs and sanity check 2024-11-30 18:26:30 +01:00
lcnr
9cba14b95b use TypingEnv when no infcx is available
the behavior of the type system not only depends on the current
assumptions, but also the currentnphase of the compiler. This is
mostly necessary as we need to decide whether and how to reveal
opaque types. We track this via the `TypingMode`.
2024-11-18 10:38:56 +01:00
Jubilee Young
092135b7b4 compiler: Directly use rustc_abi in ty_utils 2024-11-03 13:38:47 -08:00
Jubilee Young
7086dd83cc compiler: rustc_abi::Abi => BackendRepr
The initial naming of "Abi" was an awful mistake, conveying wrong ideas
about how psABIs worked and even more about what the enum meant.
It was only meant to represent the way the value would be described to
a codegen backend as it was lowered to that intermediate representation.
It was never meant to mean anything about the actual psABI handling!
The conflation is because LLVM typically will associate a certain form
with a certain ABI, but even that does not hold when the special cases
that actually exist arise, plus the IR annotations that modify the ABI.

Reframe `rustc_abi::Abi` as the `BackendRepr` of the type, and rename
`BackendRepr::Aggregate` as `BackendRepr::Memory`. Unfortunately, due to
the persistent misunderstandings, this too is now incorrect:
- Scattered ABI-relevant code is entangled with BackendRepr
- We do not always pre-compute a correct BackendRepr that reflects how
  we "actually" want this value to be handled, so we leave the backend
  interface to also inject various special-cases here
- In some cases `BackendRepr::Memory` is a "real" aggregate, but in
  others it is in fact using memory, and in some cases it is a scalar!

Our rustc-to-backend lowering code handles this sort of thing right now.
That will eventually be addressed by lifting duplicated lowering code
to either rustc_codegen_ssa or rustc_target as appropriate.
2024-10-29 14:56:00 -07:00
Jubilee Young
88a9edc091 compiler: Add is_uninhabited and use LayoutS accessors
This reduces the need of the compiler to peek on the fields of LayoutS.
2024-10-28 09:58:30 -07:00
Jubilee Young
68d1fd9427 compiler: pre-move code for fixing enum layout ICEs 2024-10-20 02:09:22 -07:00