Initial public commit of ISLE prototype DSL compiler.

cranelift/isle/src/lower.rs

@@ -0,0 +1,33 @@
+use crate::ir::*;
+use crate::sema;
+
+struct LowerState<'a> {
+    tyenv: &'a sema::TypeEnv,
+    func: &'a sema::Func,
+    builder: FuncBuilder,
+    control_flow: ControlInput,
+}
+
+pub fn lower(tyenv: &sema::TypeEnv, func: &sema::Func) -> Func {
+    let mut builder = FuncBuilder::default();
+    let entry = builder.intern(Node::Entry);
+
+    let mut state = LowerState {
+        tyenv,
+        func,
+        builder,
+        control_flow: ControlInput(entry, 0),
+    };
+
+    if !func.is_extern && !func.is_inline {
+        for case in &func.cases {
+            state.lower_case(case);
+        }
+    }
+
+    state.builder.build()
+}
+
+impl<'a> LowerState<'a> {
+    fn lower_case(&mut self) {}
+}