From d3471ed1af1e9c617dca7848d8107ad44860305e Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Sun, 11 Aug 2024 19:25:37 +0100
Subject: [PATCH] Make primitive arithmetic operations compile to bytecode

---
 src/compiler.cpp | 33 ++++++++++++++++++++++++++++-----
 src/vli.cpp      |  6 ++----
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/src/compiler.cpp b/src/compiler.cpp
index 863358c..3274d83 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -98,6 +98,19 @@ Result<Expression> Compiler::compile_primop(Context& context, Symbol& op,
   Value cur = TRY(expr.rest());
   Expression ex = TRY(Expression::create());
 
+  Oc opcode = Oc::Unknown;
+  const char* name = "";
+
+  if (TRY(op.cmp("+")) == 0) {
+    opcode = Oc::Add;
+    name = "add";
+  } else if (TRY(op.cmp("*")) == 0) {
+    opcode = Oc::Mul;
+    name = "mul";
+  } else {
+    return ERROR(NotImplemented);
+  }
+
   if (cur.is<Nil>()) {
     uint64_t reg = context.alloc_reg();
     int64_t zero = TRY(context.add_const(TRY(Value::create((int64_t)0))));
@@ -113,7 +126,8 @@ Result<Expression> Compiler::compile_primop(Context& context, Symbol& op,
   auto comp = TRY(compile_expr(context, subexpr));
 
   ex.add_code(comp.code);
-  uint64_t reg = comp.reg;
+  uint64_t firstreg = comp.reg;
+  uint64_t reg = firstreg;
 
   cur = TRY(pair.rest());
 
@@ -125,15 +139,24 @@ Result<Expression> Compiler::compile_primop(Context& context, Symbol& op,
 
     ex.add_code(comp.code);
 
-    uint64_t res = context.alloc_reg();
-    std::cout << "add r" << res << ", r" << reg << ", r" << comp.reg << "\n";
-    TRY(ex.add_opcode(Oc::Add, {0, (int64_t)res}, {0, (int64_t)reg},
+    auto rest = TRY(pair.rest());
+
+    uint64_t res = 0;
+    if (rest.is<Nil>())
+      res = firstreg;
+    else
+      res = context.alloc_reg();
+
+    std::cout << name << " r" << res << ", r" << reg << ", r" << comp.reg
+              << "\n";
+    TRY(ex.add_opcode(opcode, {0, (int64_t)res}, {0, (int64_t)reg},
                       {0, (int64_t)comp.reg}));
 
     reg = res;
-    cur = TRY(pair.rest());
+    cur = std::move(rest);
   }
 
+  context.maxreg = firstreg + 1;
   ex.reg = reg;
   return std::move(ex);
 }
diff --git a/src/vli.cpp b/src/vli.cpp
index 706828c..d30e9fd 100644
--- a/src/vli.cpp
+++ b/src/vli.cpp
@@ -9,13 +9,11 @@
 StaticArena<64 * 1024 * 1024> arena;
 
 int main() {
-  auto s = DIEX(String::create("(+ (+ 1 2 3) 4)"));
+  auto s = DIEX(String::create("(* (+ 1 2 3) 4)"));
   auto reader = Reader(s);
 
   auto r = DIEX(reader.read_one());
-
-  auto writer = Writer();
-  auto s2 = DIEX(writer.write_one(r));
+  auto s2 = DIEX(write_one(r));
 
   DIEX(arena_gc());