moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

cranelift/module/src/backend.rs

@@ -0,0 +1,129 @@
+//! Defines the `Backend` trait.
+
+use crate::DataContext;
+use crate::Linkage;
+use crate::ModuleNamespace;
+use crate::ModuleResult;
+use core::marker;
+use cranelift_codegen::isa::TargetIsa;
+use cranelift_codegen::Context;
+use cranelift_codegen::{binemit, ir};
+
+/// A `Backend` implements the functionality needed to support a `Module`.
+///
+/// Two notable implementations of this trait are:
+///  - `SimpleJITBackend`, defined in [cranelift-simplejit], which JITs
+///    the contents of a `Module` to memory which can be directly executed.
+///  - `FaerieBackend`, defined in [cranelift-faerie], which writes the
+///    contents of a `Module` out as a native object file.
+///
+/// [cranelift-simplejit]: https://docs.rs/cranelift-simplejit/
+/// [cranelift-faerie]: https://docs.rs/cranelift-faerie/
+pub trait Backend
+where
+    Self: marker::Sized,
+{
+    /// A builder for constructing `Backend` instances.
+    type Builder;
+
+    /// The results of compiling a function.
+    type CompiledFunction;
+
+    /// The results of "compiling" a data object.
+    type CompiledData;
+
+    /// The completed output artifact for a function, if this is meaningful for
+    /// the `Backend`.
+    type FinalizedFunction;
+
+    /// The completed output artifact for a data object, if this is meaningful for
+    /// the `Backend`.
+    type FinalizedData;
+
+    /// This is an object returned by `Module`'s
+    /// [`finish`](struct.Module.html#method.finish) function,
+    /// if the `Backend` has a purpose for this.
+    type Product;
+
+    /// Create a new `Backend` instance.
+    fn new(_: Self::Builder) -> Self;
+
+    /// Return the `TargetIsa` to compile for.
+    fn isa(&self) -> &TargetIsa;
+
+    /// Declare a function.
+    fn declare_function(&mut self, name: &str, linkage: Linkage);
+
+    /// Declare a data object.
+    fn declare_data(&mut self, name: &str, linkage: Linkage, writable: bool);
+
+    /// Define a function, producing the function body from the given `Context`.
+    ///
+    /// Functions must be declared before being defined.
+    fn define_function(
+        &mut self,
+        name: &str,
+        ctx: &Context,
+        namespace: &ModuleNamespace<Self>,
+        code_size: u32,
+    ) -> ModuleResult<Self::CompiledFunction>;
+
+    /// Define a zero-initialized data object of the given size.
+    ///
+    /// Data objects must be declared before being defined.
+    fn define_data(
+        &mut self,
+        name: &str,
+        writable: bool,
+        data_ctx: &DataContext,
+        namespace: &ModuleNamespace<Self>,
+    ) -> ModuleResult<Self::CompiledData>;
+
+    /// Write the address of `what` into the data for `data` at `offset`. `data` must refer to a
+    /// defined data object.
+    fn write_data_funcaddr(
+        &mut self,
+        data: &mut Self::CompiledData,
+        offset: usize,
+        what: ir::FuncRef,
+    );
+
+    /// Write the address of `what` plus `addend` into the data for `data` at `offset`. `data` must
+    /// refer to a defined data object.
+    fn write_data_dataaddr(
+        &mut self,
+        data: &mut Self::CompiledData,
+        offset: usize,
+        what: ir::GlobalValue,
+        addend: binemit::Addend,
+    );
+
+    /// Perform all outstanding relocations on the given function. This requires all `Local`
+    /// and `Export` entities referenced to be defined.
+    fn finalize_function(
+        &mut self,
+        func: &Self::CompiledFunction,
+        namespace: &ModuleNamespace<Self>,
+    ) -> Self::FinalizedFunction;
+
+    /// Return the finalized artifact from the backend, if relevant.
+    fn get_finalized_function(&self, func: &Self::CompiledFunction) -> Self::FinalizedFunction;
+
+    /// Perform all outstanding relocations on the given data object. This requires all
+    /// `Local` and `Export` entities referenced to be defined.
+    fn finalize_data(
+        &mut self,
+        data: &Self::CompiledData,
+        namespace: &ModuleNamespace<Self>,
+    ) -> Self::FinalizedData;
+
+    /// Return the finalized artifact from the backend, if relevant.
+    fn get_finalized_data(&self, data: &Self::CompiledData) -> Self::FinalizedData;
+
+    /// "Publish" all finalized functions and data objects to their ultimate destinations.
+    fn publish(&mut self);
+
+    /// Consume this `Backend` and return a result. Some implementations may
+    /// provide additional functionality through this result.
+    fn finish(self) -> Self::Product;
+}