Rename the 'cretonne' crate to 'cretonne-codegen'.

This fixes the next part of #287.

lib/codegen/src/binemit/memorysink.rs

@@ -0,0 +1,125 @@
+//! Code sink that writes binary machine code into contiguous memory.
+//!
+//! The `CodeSink` trait is the most general way of extracting binary machine code from Cretonne,
+//! and it is implemented by things like the `test binemit` file test driver to generate
+//! hexadecimal machine code. The `CodeSink` has some undesirable performance properties because of
+//! the dual abstraction: `TargetIsa` is a trait object implemented by each supported ISA, so it
+//! can't have any generic functions that could be specialized for each `CodeSink` implementation.
+//! This results in many virtual function callbacks (one per `put*` call) when
+//! `TargetIsa::emit_inst()` is used.
+//!
+//! The `MemoryCodeSink` type fixes the performance problem because it is a type known to
+//! `TargetIsa` so it can specialize its machine code generation for the type. The trade-off is
+//! that a `MemoryCodeSink` will always write binary machine code to raw memory. It forwards any
+//! relocations to a `RelocSink` trait object. Relocations are less frequent than the
+//! `CodeSink::put*` methods, so the performance impact of the virtual callbacks is less severe.
+
+use super::{Addend, CodeOffset, CodeSink, Reloc};
+use ir::{ExternalName, JumpTable, SourceLoc, TrapCode};
+use std::ptr::write_unaligned;
+
+/// A `CodeSink` that writes binary machine code directly into memory.
+///
+/// A `MemoryCodeSink` object should be used when emitting a Cretonne IR function into executable
+/// memory. It writes machine code directly to a raw pointer without any bounds checking, so make
+/// sure to allocate enough memory for the whole function. The number of bytes required is returned
+/// by the `Context::compile()` function.
+///
+/// Any relocations in the function are forwarded to the `RelocSink` trait object.
+///
+/// Note that `MemoryCodeSink` writes multi-byte values in the native byte order of the host. This
+/// is not the right thing to do for cross compilation.
+pub struct MemoryCodeSink<'a> {
+    data: *mut u8,
+    offset: isize,
+    relocs: &'a mut RelocSink,
+    traps: &'a mut TrapSink,
+}
+
+impl<'a> MemoryCodeSink<'a> {
+    /// Create a new memory code sink that writes a function to the memory pointed to by `data`.
+    pub fn new<'sink>(
+        data: *mut u8,
+        relocs: &'sink mut RelocSink,
+        traps: &'sink mut TrapSink,
+    ) -> MemoryCodeSink<'sink> {
+        MemoryCodeSink {
+            data,
+            offset: 0,
+            relocs,
+            traps,
+        }
+    }
+}
+
+/// A trait for receiving relocations for code that is emitted directly into memory.
+pub trait RelocSink {
+    /// Add a relocation referencing an EBB at the current offset.
+    fn reloc_ebb(&mut self, CodeOffset, Reloc, CodeOffset);
+
+    /// Add a relocation referencing an external symbol at the current offset.
+    fn reloc_external(&mut self, CodeOffset, Reloc, &ExternalName, Addend);
+
+    /// Add a relocation referencing a jump table.
+    fn reloc_jt(&mut self, CodeOffset, Reloc, JumpTable);
+}
+
+/// A trait for receiving trap codes and offsets.
+pub trait TrapSink {
+    /// Add trap information for a specific offset.
+    fn trap(&mut self, CodeOffset, SourceLoc, TrapCode);
+}
+
+impl<'a> CodeSink for MemoryCodeSink<'a> {
+    fn offset(&self) -> CodeOffset {
+        self.offset as CodeOffset
+    }
+
+    fn put1(&mut self, x: u8) {
+        unsafe {
+            write_unaligned(self.data.offset(self.offset), x);
+        }
+        self.offset += 1;
+    }
+
+    fn put2(&mut self, x: u16) {
+        unsafe {
+            write_unaligned(self.data.offset(self.offset) as *mut u16, x);
+        }
+        self.offset += 2;
+    }
+
+    fn put4(&mut self, x: u32) {
+        unsafe {
+            write_unaligned(self.data.offset(self.offset) as *mut u32, x);
+        }
+        self.offset += 4;
+    }
+
+    fn put8(&mut self, x: u64) {
+        unsafe {
+            write_unaligned(self.data.offset(self.offset) as *mut u64, x);
+        }
+        self.offset += 8;
+    }
+
+    fn reloc_ebb(&mut self, rel: Reloc, ebb_offset: CodeOffset) {
+        let ofs = self.offset();
+        self.relocs.reloc_ebb(ofs, rel, ebb_offset);
+    }
+
+    fn reloc_external(&mut self, rel: Reloc, name: &ExternalName, addend: Addend) {
+        let ofs = self.offset();
+        self.relocs.reloc_external(ofs, rel, name, addend);
+    }
+
+    fn reloc_jt(&mut self, rel: Reloc, jt: JumpTable) {
+        let ofs = self.offset();
+        self.relocs.reloc_jt(ofs, rel, jt);
+    }
+
+    fn trap(&mut self, code: TrapCode, srcloc: SourceLoc) {
+        let ofs = self.offset();
+        self.traps.trap(ofs, srcloc, code);
+    }
+}