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(ns cljcc.emit
(:require [cljcc.parser :as p]
[cljcc.util :refer [get-os]]
[cljcc.compiler :as c]
[clojure.string :as str]
[clojure.pprint :as pp]))
;;;; Operand Emit
(defn- imm-opernad-emit [operand]
(format "$%d" (:value operand)))
(defn- stack-operand-emit [operand]
(format "%d(%%rbp)" (:value operand)))
(defn- register-operand [operand]
(condp = (:register operand)
:ax "%eax"
:dx "%edx"
:r10 "%r10d"
:r11 "%r11d"
(throw (AssertionError. (str "Invalid register operand: " operand)))))
(def operand-emitters
"Map of assembly operands to operand emitters."
{:imm #'imm-opernad-emit
:reg #'register-operand
:stack #'stack-operand-emit})
(defn- operand-emit [operand]
(if-let [[_ operand-emit-fn] (find operand-emitters (:operand operand))]
(operand-emit-fn operand)
(throw (AssertionError. (str "Invalid operand: " operand)))))
;;;; Instruction Emit
(defn- mov-instruction-emit [instruction]
(let [src (operand-emit (:src instruction))
dst (operand-emit (:dst instruction))]
[(format " %s %s, %s" "movl" src dst)]))
(defn- ret-instruction-emit [_instruction]
[" movq %rbp, %rsp"
" popq %rbp"
" ret"])
(defn- unary-instruction-emit [instruction]
(let [operand (operand-emit (:operand instruction))
assembly-operator (condp = (:unary-operator instruction)
:complement "notl"
:hyphen "negl"
(throw (AssertionError. (str "Invalid unary operator: " instruction))))]
[(format " %s %s" assembly-operator operand)]))
(defn- binary-instruction-emit [instruction]
(let [src (operand-emit (:src instruction))
dst (operand-emit (:dst instruction))
binop (:binary-operator instruction)
binop-operator (condp = binop
:add "addl"
:sub "subl"
:mul "imull"
:bit-and "andl"
:bit-xor "xorl"
:bit-or "orl"
:bit-left-shift "sall"
:bit-right-shift "sarl"
(throw (AssertionError. (str "Invalid binary operator: " instruction))))]
[(format " %s %s, %s" binop-operator src dst)]))
(defn- cdq-instruction-emit [_instruction]
[" cdq"])
(defn- idiv-instruction-emit [instruction]
[(format " idivl %s" (operand-emit (:operand instruction)))])
(defn- allocate-stack-instruction-emit [instruction]
[(format " subq $%d, %%rsp" (:value instruction))])
(def instruction-emitters
"Map of assembly instructions to function emitters."
{:mov #'mov-instruction-emit
:ret #'ret-instruction-emit
:binary #'binary-instruction-emit
:cdq #'cdq-instruction-emit
:idiv #'idiv-instruction-emit
:unary #'unary-instruction-emit
:allocate-stack #'allocate-stack-instruction-emit})
(defn instruction-emit [instruction]
(if-let [[_ instruction-emit-fn] (find instruction-emitters (:op instruction))]
(instruction-emit-fn instruction)
(throw (AssertionError. (str "Invalid instruction: " instruction)))))
(defn- handle-function-name [name]
(if (= :mac (get-os))
(str "_" name)
name))
(defn function-emit [f]
(let [name (handle-function-name (:identifier f))
globl (format " .globl %s", name)
name-line (format "%s:" name)
instructions (map instruction-emit (:instructions f))]
(flatten [globl
name-line
" pushq %rbp"
" movq %rsp, %rbp"
instructions])))
(def emitters-top-level
"Map of assembly top level constructs to their emitters."
{:function #'function-emit})
(defn emit-top-level [assembly-ast]
(if-let [[_ emit-fn] (find emitters-top-level (:op assembly-ast))]
(emit-fn assembly-ast)
(throw (AssertionError. (str "Invalid ast: " assembly-ast)))))
(def linux-assembly-end ".section .note.GNU-stack,\"\",@progbits")
(defn emit [ast]
(let [handle-os (fn [ast]
(if (= :linux (get-os))
(conj (vec ast) linux-assembly-end)
ast))]
(->> ast
(map emit-top-level)
concat
flatten
handle-os
(str/join "\n"))))
(comment
(def ex "int main(void) {return 2;}")
(mov-instruction-emit
{:op :mov
:src {:operand :imm :value 1}
:dst {:operand :stack :value -4}})
(c/generate-assembly
"int main(void) {
return ~(-(~(-1)));
}")
(pp/pprint
(c/generate-assembly
"int main(void) {
return ~(-(~(-1)));
}"))
(println
(emit
(c/generate-assembly
"int main(void) {
return 6 / 3 / 2;
}")))
(println
(emit
(c/generate-assembly
"int main(void) {
return 6;
}")))
(-> ex
p/parse)
())
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