From 7a3e7151ea7e05952ec58648d71d9ed33168109d Mon Sep 17 00:00:00 2001
From: Shagun Agrawal <agrawalshagun07@gmail.com>
Date: Thu, 22 Aug 2024 22:45:34 +0530
Subject: Add tacky generation for declarations, statements

---
 src/cljcc/analyzer.clj |  4 +--
 src/cljcc/tacky.clj    | 70 ++++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 61 insertions(+), 13 deletions(-)

(limited to 'src/cljcc')

diff --git a/src/cljcc/analyzer.clj b/src/cljcc/analyzer.clj
index 5eb03ee..504e8ab 100644
--- a/src/cljcc/analyzer.clj
+++ b/src/cljcc/analyzer.clj
@@ -68,7 +68,7 @@
                       {:body []
                        :variable-map {}}
                       (:body f))]
-    (assoc f :body updated-body)))
+    (assoc f :body (:body updated-body))))
 
 (defn validate [ast]
   (map validate-function ast))
@@ -90,7 +90,7 @@ return 0;
 }"))
 
   (pp/pprint
-   (p/parse-from-src
+   (validate-from-src
     "int main (void) {
 int x;
 int a = -1;
diff --git a/src/cljcc/tacky.clj b/src/cljcc/tacky.clj
index b7d6e2e..ffa85b1 100644
--- a/src/cljcc/tacky.clj
+++ b/src/cljcc/tacky.clj
@@ -3,7 +3,8 @@
    [clojure.pprint :as pp]
    [cljcc.lexer :as l]
    [cljcc.util :as u]
-   [cljcc.parser :as p]))
+   [cljcc.parser :as p]
+   [cljcc.analyzer :as a]))
 
 (defn- variable
   ([]
@@ -12,6 +13,10 @@
    {:type :variable
     :value (u/create-identifier! (str identifier))}))
 
+(defn- parsed-var->tacky-var [v]
+  {:type :variable
+   :value (:identifier v)})
+
 (defn- label
   ([] (label "label"))
   ([ident] (u/create-identifier! ident)))
@@ -158,6 +163,13 @@
                              (copy-instruction (constant 1) res)
                              (label-instruction false-label)])}))
 
+(defn- assignment-exp-handler [e]
+  (let [var (parsed-var->tacky-var (:left e)) ; guaranteed to be parsed variable
+        rhs (expression-handler (:right e))]
+    {:val var
+     :instructions (flatten [(:instructions rhs)
+                             (copy-instruction (:val rhs) var)])}))
+
 (defn- expression-handler [e]
   (when-let [exp-type (:exp-type e)]
     (cond
@@ -168,29 +180,65 @@
                                    :logical-and (logical-and-handler e)
                                    :logical-or (logical-or-handler e)
                                    (binary-expr-handler e)))
+      (= exp-type :variable-exp) {:val (parsed-var->tacky-var e)}
+      (= exp-type :assignment-exp) (assignment-exp-handler e)
       :else (throw (ex-info "Tacky error. Invalid expression." {e e})))))
 
 (defn- exp-instructions [exp]
   (expression-handler exp))
 
-(defn- ret-instructions [exp]
-  (let [e (exp-instructions exp)
-        val (:val e)
-        instructions (:instructions e)]
-    (conj (vec instructions) (return-instruction val))))
-
-(defn ast-statement->tacky-instructions [statement]
-  (remove nil? (ret-instructions (:value statement))))
+(defn- statement->tacky-instruction [s]
+  (condp = (:statement-type s)
+    :return (let [e (exp-instructions (:value s))
+                  val (:val e)
+                  instructions (:instructions e)]
+              (conj (vec instructions) (return-instruction val)))
+    :expression [(:instructions (exp-instructions (:value s)))]
+    :empty []
+    (throw (ex-info "Tacky error. Invalid statement." {:statement s}))))
+
+(defn- declaration->tacky-instruction [d]
+  (when (:initial d)
+    (let [var (parsed-var->tacky-var d) ; only needs :identifier key in declaration
+          rhs (exp-instructions (:initial d))]
+      (flatten [(:instructions rhs) (copy-instruction (:val rhs) var)]))))
+
+(defn- block-item->tacky-instruction [item]
+  (condp = (:type item)
+    :statement (statement->tacky-instruction item)
+    :declaration (declaration->tacky-instruction item)
+    (throw (ex-info "Tacky error. Invalid block item." {:item item}))))
+
+(defn- function-body->tacky-instructions [body]
+  (let [v (->> body
+               (remove nil?)
+               (map block-item->tacky-instruction)
+               flatten
+               (remove nil?))]
+    (conj (vec v) (return-instruction (constant 0)))))
 
 (defn tacky-generate [ast]
   (map (fn [f]
          (-> f
-             (assoc :instructions (flatten (map ast-statement->tacky-instructions (:statements f))))
-             (dissoc :statements)))
+             (assoc :instructions (function-body->tacky-instructions (:body f)))
+             (dissoc :body)))
        ast))
 
+(defn tacky-from-src [src]
+  (-> src
+      l/lex
+      p/parse
+      a/validate
+      tacky-generate))
+
 (comment
 
+  (pp/pprint
+   (tacky-from-src
+    "int main(void) {
+2 + 2;
+}"))
+
   (pp/pprint
    (tacky-generate
     (p/parse (l/lex "int main(void) {return -(~1);}"))))
-- 
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