Add a Context::emit_to_memory function.

This function will emit the binary machine code into contiguous raw
memory while sending relocations to a RelocSink.

Add a MemoryCodeSink for generating machine code directly into memory
efficiently. Allow the TargetIsa to provide emit_function
implementations that are specialized to the MemoryCodeSink type to avoid
needless small virtual callbacks to put1() et etc.

lib/cretonne/src/isa/arm32/mod.rs

@@ -6,7 +6,7 @@ mod binemit;
 mod enc_tables;
 mod registers;
 
-use binemit::CodeSink;
+use binemit::{CodeSink, MemoryCodeSink, emit_function};
 use super::super::settings as shared_settings;
 use isa::enc_tables::{self as shared_enc_tables, lookup_enclist, Encodings};
 use isa::Builder as IsaBuilder;
@@ -95,6 +95,10 @@ impl TargetIsa for Isa {
         binemit::emit_inst(func, inst, sink)
     }
 
+    fn emit_function(&self, func: &ir::Function, sink: &mut MemoryCodeSink) {
+        emit_function(func, binemit::emit_inst, sink)
+    }
+
     fn reloc_names(&self) -> &'static [&'static str] {
         &binemit::RELOC_NAMES
     }

lib/cretonne/src/isa/arm64/mod.rs

@@ -6,7 +6,7 @@ mod binemit;
 mod enc_tables;
 mod registers;
 
-use binemit::CodeSink;
+use binemit::{CodeSink, MemoryCodeSink, emit_function};
 use super::super::settings as shared_settings;
 use isa::enc_tables::{lookup_enclist, Encodings};
 use isa::Builder as IsaBuilder;
@@ -88,6 +88,10 @@ impl TargetIsa for Isa {
         binemit::emit_inst(func, inst, sink)
     }
 
+    fn emit_function(&self, func: &ir::Function, sink: &mut MemoryCodeSink) {
+        emit_function(func, binemit::emit_inst, sink)
+    }
+
     fn reloc_names(&self) -> &'static [&'static str] {
         &binemit::RELOC_NAMES
     }

lib/cretonne/src/isa/intel/mod.rs

@@ -6,7 +6,7 @@ mod binemit;
 mod enc_tables;
 mod registers;
 
-use binemit::CodeSink;
+use binemit::{CodeSink, MemoryCodeSink, emit_function};
 use super::super::settings as shared_settings;
 use isa::enc_tables::{self as shared_enc_tables, lookup_enclist, Encodings};
 use isa::Builder as IsaBuilder;
@@ -95,6 +95,10 @@ impl TargetIsa for Isa {
         binemit::emit_inst(func, inst, sink)
     }
 
+    fn emit_function(&self, func: &ir::Function, sink: &mut MemoryCodeSink) {
+        emit_function(func, binemit::emit_inst, sink)
+    }
+
     fn reloc_names(&self) -> &'static [&'static str] {
         &binemit::RELOC_NAMES
     }

lib/cretonne/src/isa/mod.rs

@@ -44,7 +44,7 @@ pub use isa::constraints::{RecipeConstraints, OperandConstraint, ConstraintKind,
 pub use isa::encoding::{Encoding, EncInfo};
 pub use isa::registers::{RegInfo, RegUnit, RegClass, RegClassIndex, regs_overlap};
 
-use binemit::CodeSink;
+use binemit;
 use settings;
 use ir;
 use regalloc;
@@ -215,7 +215,12 @@ pub trait TargetIsa {
     ///
     /// Note that this will call `put*` methods on the trait object via its vtable which is not the
     /// fastest way of emitting code.
-    fn emit_inst(&self, func: &ir::Function, inst: ir::Inst, sink: &mut CodeSink);
+    fn emit_inst(&self, func: &ir::Function, inst: ir::Inst, sink: &mut binemit::CodeSink);
+
+    /// Emit a whole function into memory.
+    ///
+    /// This is more performant than calling `emit_inst` for each instruction.
+    fn emit_function(&self, func: &ir::Function, sink: &mut binemit::MemoryCodeSink);
 
     /// Get a static array of names associated with relocations in this ISA.
     ///

lib/cretonne/src/isa/riscv/mod.rs

@@ -7,7 +7,7 @@ mod enc_tables;
 mod registers;
 
 use super::super::settings as shared_settings;
-use binemit::CodeSink;
+use binemit::{CodeSink, MemoryCodeSink, emit_function};
 use isa::enc_tables::{self as shared_enc_tables, lookup_enclist, Encodings};
 use isa::Builder as IsaBuilder;
 use isa::{TargetIsa, RegInfo, RegClass, EncInfo, Legalize};
@@ -95,6 +95,10 @@ impl TargetIsa for Isa {
         binemit::emit_inst(func, inst, sink)
     }
 
+    fn emit_function(&self, func: &ir::Function, sink: &mut MemoryCodeSink) {
+        emit_function(func, binemit::emit_inst, sink)
+    }
+
     fn reloc_names(&self) -> &'static [&'static str] {
         &binemit::RELOC_NAMES
     }