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Diffstat (limited to 'src/doc/rustc-dev-guide/src/backend/backend-agnostic.md')
| -rw-r--r-- | src/doc/rustc-dev-guide/src/backend/backend-agnostic.md | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/src/doc/rustc-dev-guide/src/backend/backend-agnostic.md b/src/doc/rustc-dev-guide/src/backend/backend-agnostic.md index ea50cd754..c5eb57e64 100644 --- a/src/doc/rustc-dev-guide/src/backend/backend-agnostic.md +++ b/src/doc/rustc-dev-guide/src/backend/backend-agnostic.md @@ -2,16 +2,21 @@ <!-- toc --> -As of <!-- date-check --> Aug 2022, `rustc_codegen_ssa` provides an -abstract interface for all backends to implement, to allow other codegen -backends (e.g. [Cranelift]). +[`rustc_codegen_ssa`] +provides an abstract interface for all backends to implement, +namely LLVM, [Cranelift], and [GCC]. -[Cranelift]: https://github.com/bytecodealliance/wasmtime/tree/HEAD/cranelift +[Cranelift]: https://github.com/bjorn3/rustc_codegen_cranelift +[GCC]: https://github.com/rust-lang/rustc_codegen_gcc +[`rustc_codegen_ssa`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_codegen_ssa/index.html -# Refactoring of `rustc_codegen_llvm` +Below is some background information on the refactoring that created this +abstract interface. + +## Refactoring of `rustc_codegen_llvm` by Denis Merigoux, October 23rd 2018 -## State of the code before the refactoring +### State of the code before the refactoring All the code related to the compilation of MIR into LLVM IR was contained inside the `rustc_codegen_llvm` crate. Here is the breakdown of the most @@ -51,7 +56,7 @@ While the LLVM-specific code will be left in `rustc_codegen_llvm`, all the new traits and backend-agnostic code will be moved in `rustc_codegen_ssa` (name suggestion by @eddyb). -## Generic types and structures +### Generic types and structures @irinagpopa started to parametrize the types of `rustc_codegen_llvm` by a generic `Value` type, implemented in LLVM by a reference `&'ll Value`. This @@ -103,7 +108,7 @@ of the backend and it makes more sense to leave their definition to the backend implementor than to allow just a narrow spot via a generic field for the backend's context. -## Traits and interface +### Traits and interface Because they have to be defined by the backend, `CodegenCx` and `Builder` will be the structures implementing all the traits defining the backend's interface. @@ -170,7 +175,7 @@ called. However, when implementing a Rust backend for `rustc`, these methods will need information from `CodegenCx`, hence the additional parameter (unused in the LLVM implementation of the trait). -## State of the code after the refactoring +### State of the code after the refactoring The traits offer an API which is very similar to the API of LLVM. This is not the best solution since LLVM has a very special way of doing things: when |