From e0de6ddf16a37435966e31a73b4425a0300dc1e6 Mon Sep 17 00:00:00 2001
From: Shagun Agrawal <agrawalshagun07@gmail.com>
Date: Sat, 3 Aug 2024 02:45:43 +0530
Subject: Add tacky IR stage

Add Tacky IR stage

General formatting etc
---
 src/cljcc/tacky.clj | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100644 src/cljcc/tacky.clj

(limited to 'src/cljcc/tacky.clj')

diff --git a/src/cljcc/tacky.clj b/src/cljcc/tacky.clj
new file mode 100644
index 0000000..e25c87f
--- /dev/null
+++ b/src/cljcc/tacky.clj
@@ -0,0 +1,118 @@
+(ns cljcc.tacky
+  (:require
+   [clojure.pprint :as pp]
+   [instaparse.core :as insta]
+   [cljcc.parser :as p]))
+
+(def counter "Global integer counter for generating unique identifier names." (atom 0))
+
+(defn create-identifier
+  "Returns a unique identifier. Used for generating tacky variable names."
+  ([]
+   (create-identifier "tmp"))
+  ([identifier]
+   (let [n @counter
+         _ (swap! counter #(+ % 1))]
+     (str identifier "." n))))
+
+(defn variable
+  ([]
+   {:type :variable
+    :value (create-identifier)})
+  ([^String identifier]
+   {:type :variable
+    :value (create-identifier identifier)}))
+
+(defn constant [^String v]
+  {:type :constant
+   :value (Long. v)})
+
+(defn unop-operator [^String unop]
+  (condp = unop
+    "~" :complement
+    "-" :negate))
+
+(defn unary-instruction [unop src dst]
+  {:type :unary
+   :unary-operator unop
+   :dst dst
+   :src src})
+
+(defn return-instruction [val]
+  {:type :return
+   :val val})
+
+(defn exp-instructions [exp]
+  (when-let [expr (second exp)]
+    (condp = (first expr)
+      :constant {:val (constant (second expr))}
+      :unop-exp (let [inner (exp-instructions (nth expr 2))
+                      dst (variable)
+                      src (:val inner)
+                      unop (unop-operator (second (second expr)))
+                      inst (unary-instruction unop  src dst)]
+                  {:val dst
+                   :instructions (conj (:instructions inner) inst)}))))
+
+(defn ret-instructions [exp]
+  (let [e (exp-instructions exp)
+        val (:val e)
+        instructions (:instructions e)]
+    (conj instructions (return-instruction val))))
+
+(defn statement-transform [_ret-keyword exp]
+  (reverse (ret-instructions exp)))
+
+(defn tacky-generate [ast]
+  (insta/transform {:statement statement-transform} ast))
+
+(comment
+
+  (reset! counter 0)
+
+  (pp/pprint (tacky-generate (p/parse "int main(void) {return -~-8;}")))
+
+  (pp/pprint
+   (exp-instructions [:exp [:constant "2"]]))
+
+  (pp/pprint
+   (exp-instructions [:exp [:constant "2"]]))
+
+  (pp/pprint
+   (exp-instructions [:exp [:unop-exp [:unop "-"] [:exp [:constant "2"]]]]))
+
+  (def ex-exp
+    [:exp
+     [:unop-exp
+      [:unop "-"]
+      [:exp
+       [:unop-exp
+        [:unop "~"]
+        [:exp [:unop-exp [:unop "-"] [:exp [:constant "8"]]]]]]]])
+
+  (def ex-ret
+    [:statement "return"
+     [:exp
+      [:unop-exp
+       [:unop "-"]
+       [:exp
+        [:unop-exp
+         [:unop "~"]
+         [:exp [:unop-exp [:unop "-"] [:exp [:constant "8"]]]]]]]]])
+
+  (pp/pprint
+   (exp-instructions ex-exp))
+
+  (pp/pprint
+   (ret-instructions ex-ret))
+
+ (def exprg
+   "int main(void) {
+     return -(~(-8));
+   }")
+
+ (pp/pprint (parse "int main(void) {return 2;}"))
+
+ (pp/pprint (parse exprg))
+
+ ,)
-- 
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