From cc4ba445a7ccec87ff987a27008781c995afb045 Mon Sep 17 00:00:00 2001
From: sfja <sfja2004@gmail.com>
Date: Wed, 29 Apr 2026 23:06:47 +0200
Subject: [PATCH] add mir_lowerer

---
 src/lir.ts       | 32 +++++++++--------
 src/mir_lower.ts | 94 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+), 15 deletions(-)
 create mode 100644 src/mir_lower.ts

diff --git a/src/lir.ts b/src/lir.ts
index 5e72e5f..5c0cc35 100644
--- a/src/lir.ts
+++ b/src/lir.ts
@@ -96,6 +96,23 @@ export type TyKind =
     | { tag: "Ptr" }
     | { tag: "Array"; ty: Ty; length: number };
 
+export class Builder {
+    constructor(
+        private bb: BasicBlock,
+        private cx: Context,
+    ) {}
+
+    createInt(ty: Ty, value: number): Inst {
+        return this.push(ty, { tag: "Int", value });
+    }
+
+    private push(ty: Ty, kind: InstKind): Inst {
+        const inst = this.cx.createInst(this.bb, ty, kind);
+        this.bb.insts.push(inst);
+        return inst;
+    }
+}
+
 export class Context {
     private tys = new Map<string, Ty>();
     private instsHashIds = new Map<Inst, number>();
@@ -219,18 +236,3 @@ export class Context {
         }
     }
 }
-
-export class Builder {
-    constructor(
-        private bb: BasicBlock,
-        private cx: Context,
-    ) {}
-
-    createInt(ty: Ty, value: number) {
-        this.push(ty, { tag: "Int", value });
-    }
-
-    private push(ty: Ty, kind: InstKind) {
-        this.bb.insts.push(this.cx.createInst(this.bb, ty, kind));
-    }
-}
diff --git a/src/mir_lower.ts b/src/mir_lower.ts
new file mode 100644
index 0000000..7baf08e
--- /dev/null
+++ b/src/mir_lower.ts
@@ -0,0 +1,94 @@
+import * as mir from "./mir.ts";
+import * as lir from "./lir.ts";
+import { Ty } from "./ty.ts";
+
+export class MirModuleLowerer {
+    private cx = new lir.Context();
+
+    constructor(
+        private mod: lir.Mod,
+    ) {}
+
+    lowerFn(mirFn: mir.Fn) {
+        const lirFn = new lir.Fn(this.mod);
+        const fnLowerer = new MirFnLowerer(mirFn, lirFn, this.cx);
+        fnLowerer.lower();
+    }
+}
+
+class MirFnLowerer {
+    private insts = new Map<mir.Inst, lir.Inst>();
+
+    constructor(
+        private mirFn: mir.Fn,
+        private lirFn: lir.Fn,
+        private cx: lir.Context,
+    ) {}
+
+    lower() {
+        for (const mirBb of this.mirFn.bbs) {
+            const lirBb = new lir.BasicBlock(this.lirFn);
+            const builder = new lir.Builder(lirBb, this.cx);
+            for (const mirInst of mirBb.insts) {
+                const lirInst = this.lowerInst(mirInst, builder);
+                this.insts.set(mirInst, lirInst);
+            }
+        }
+    }
+
+    private lowerInst(inst: mir.Inst, builder: lir.Builder): lir.Inst {
+        switch (inst.kind.tag) {
+            case "Error":
+                throw new Error();
+            case "Void":
+                break;
+            case "Int": {
+                const ty = this.lowerTy(inst.ty);
+                return builder.createInt(ty, inst.kind.value);
+            }
+            case "Bool":
+            case "Str":
+            case "Array":
+            case "Fn":
+            case "Param":
+            case "GetElemPtr":
+            case "Slice":
+            case "Call":
+            case "Alloca":
+            case "Load":
+            case "Store":
+            case "Jump":
+            case "Branch":
+            case "Return":
+            case "Not":
+            case "Negate":
+            case "Eq":
+            case "Ne":
+            case "Lt":
+            case "Gt":
+            case "Lte":
+            case "Gte":
+            case "BitOr":
+            case "BitXor":
+            case "BitAnd":
+            case "Shl":
+            case "Shr":
+            case "Add":
+            case "Sub":
+            case "Mul":
+            case "Div":
+            case "Rem":
+            case "Len":
+            case "DebugPrint":
+                throw new Error(`not handled (${inst.kind.tag})`);
+        }
+    }
+
+    private lowerTy(ty: Ty): lir.Ty {
+        switch (ty.kind.tag) {
+            default:
+                throw new Error(`not handled (${ty.kind.tag})`);
+        }
+    }
+}
+