Generate binemit::emit_inst() functions.

Use the meta language encoding recipes to generate an emit_inst()
function for each ISA. The generated calls into recipe_*() functions
that must be implemented by hand.

Implement recipe_*() functions for the RISC-V recipes.

Add the TargetIsa::emit_inst() entry point which emits an instruction to
a CodeSink trait object.

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

@@ -2,14 +2,16 @@
 
 pub mod settings;
 mod abi;
+mod binemit;
 mod enc_tables;
 mod registers;
 
 use super::super::settings as shared_settings;
+use binemit::CodeSink;
 use isa::enc_tables::{self as shared_enc_tables, lookup_enclist, general_encoding};
 use isa::Builder as IsaBuilder;
 use isa::{TargetIsa, RegInfo, Encoding, Legalize, RecipeConstraints};
-use ir::{InstructionData, DataFlowGraph, Signature};
+use ir::{Function, Inst, InstructionData, DataFlowGraph, Signature};
 
 #[allow(dead_code)]
 struct Isa {
@@ -80,6 +82,10 @@ impl TargetIsa for Isa {
         // We can pass in `self.isa_flags` too, if we need it.
         abi::legalize_signature(sig, &self.shared_flags)
     }
+
+    fn emit_inst(&self, func: &Function, inst: Inst, sink: &mut CodeSink) {
+        binemit::emit_inst(func, inst, sink)
+    }
 }
 
 #[cfg(test)]