コンパイラ作成（７０） ポインタ型とint型の演算
今回の目標
引き続きポインタ型のサポートを頑張るよ。
// int*型+int型 extern void *malloc(size_t size); extern void free(void *ptr); extern int puts(char *s); int main() { int *p = malloc(10*4); for(int i = 0; i < 10; i = i + 1) printf("p + %d = %016lx\n", i, p+i); puts(""); for(int i = 0; i < 10; i = i + 1) printf("%d + p = %016lx\n", i, i+p); free(p); }
前に作ったchar*型とint型の演算を一般化するよ。
sizeof
voidとcharを追加。
# 型のサイズ def sizeof(type) if is_pointer_type?(type) then return 8 end case type when "void" return 1 when "char" return 1 when "int" return 4 when "size_t" return 8 else perror "unknown type '#{type}'" end end
これ追加したんでchar型やvoid型の変数が宣言できるようになっちゃうよ。void型の変数は拙いよね。それとvoid*型への加減算ってC言語では許されてなかった気がするなあ。これ確かgccの独自拡張かな。clang先輩もサポートしてるんでmycにも深く考えずに入れちゃったよ。うーむ。
コード生成部
今回の修正のメイン。
# 式のコード生成（二項演算の右側被演算子） def codegen_els(op, operand, type_l) if op.str == "+" then ostr = "add " elsif op.str == "-" then ostr = "sub " elsif op.str == "*" then ostr = "imul" elsif op.str == "/" then ostr = "idiv" elsif op.str == "%" then ostr = "idiv" elsif op.str == "==" then ostr = "cmp " elsif op.str == "!=" then ostr = "cmp " elsif op.str == "<" || op.str == "<" || op.str == ">" || op.str == "<=" || op.str == ">=" then ostr = "cmp " else perror "unknown operator \"" + op.str + "\"" end # 右被演算子を評価 type_r = "int" if operand.kind_of?(Array) then if operand[0].size == 2 && operand[0].kind == TK::ID && operand[1].str == "()" then codegen " sub rsp, 8" codegen " push rax" type_r = codegen_func operand codegen " mov r10d, eax" codegen " pop rax" codegen " add rsp, 8" else codegen " sub rsp, 8" codegen " push rax" type_r = codegen_el operand codegen " mov r10d, eax" codegen " pop rax" codegen " add rsp, 8" end str = "r10d" elsif operand.kind == TK::ID then v = get_var operand.str if v == nil then perror "undeclared variable \"" + operand.str + "\"" end type_r = v[0] if is_pointer_type? type_r then str = "qword ptr [rbp - " + v[1].to_s + "]" else str = "dword ptr [rbp - " + v[1].to_s + "]" end elsif operand.kind == TK::NUMBER then str = operand.str elsif operand.kind == TK::STRING then type_r = "char*" label = addliteral operand.str codegen " lea r10, "+label str = "r10" else perror end # 型チェック if type_l != type_r then if is_pointer_type?(type_l) && type_r == "int" then if op.str != "+" && op.str != "-" then perror "mismatched types to binary operation" end elsif type_l == "int" && is_pointer_type?(type_r) then if op.str != "+" && op.str != "-" then perror "mismatched types to binary operation" end else perror "mismatched types to binary operation" end elsif type_l == "char*" then perror "mismatched types to binary operation" end # 左被演算子と右被演算子とで計算 if op.str == "==" then codegen " " + ostr + " eax, " + str codegen " sete al" codegen " and eax, 1" elsif op.str == "!=" then codegen " " + ostr + " eax, " + str codegen " setne al" codegen " and eax, 1" elsif op.str == "<" then codegen " " + ostr + " eax, " + str codegen " setl al" codegen " and eax, 1" elsif op.str == ">" then codegen " " + ostr + " eax, " + str codegen " setg al" codegen " and eax, 1" elsif op.str == "<=" then codegen " " + ostr + " eax, " + str codegen " setle al" codegen " and eax, 1" elsif op.str == ">=" then codegen " " + ostr + " eax, " + str codegen " setge al" codegen " and eax, 1" elsif op.str == "*" || op.str == "/" || op.str == "%" then if str != "r10d" then codegen " mov r10d, " + str end codegen " mov r11, rdx" if op.str == "/" || op.str == "%" then codegen " cdq" end codegen " " + ostr + " r10d" if op.str == "%" then codegen " mov eax, edx" end codegen " mov rdx, r11" else if is_pointer_type?(type_l) && type_r == "int" then size = sizeof type_l[0,type_l.length-1] if str == op.str then codegen " " + ostr + " rax, " + (str.to_i*size).to_s elsif str == "r10d" then codegen " movsx r10, r10d" if size == 4 then codegen " shl r10, 2" codegen " " + ostr + " rax, r10" elsif size == 8 then codegen " shl r10, 2" codegen " " + ostr + " rax, r10" else (0...size).each do codegen " " + ostr + " rax, r10" end end else codegen " mov r10d, " + str codegen " movsx r10, r10d" if size == 4 then codegen " shl r10, 2" codegen " " + ostr + " rax, r10" elsif size == 8 then codegen " shl r10, 3" codegen " " + ostr + " rax, r10" else (0...size).each do codegen " " + ostr + " rax, r10" end end end elsif type_l == "int" && is_pointer_type?(type_r) then size = sizeof type_r[0,type_r.length-1] codegen " movsx rax, eax" if size == 1 then elsif size == 4 then codegen " shl rax, 2" elsif size == 8 then codegen " shl rax, 3" else codegen " mov r11, rax" (0...size-1).each do codegen " add rax, r11" end end codegen " " + ostr + " rax, " + str type_l = type_r else codegen " " + ostr + " eax, " + str end end return type_l end
型チェックのとこと実際に加減算してるとこを修正。型を見て正しいサイズで加減算してる。サイズが4、8の時はshl使ってるけど、それ以外の時はaddをサイズ分繰り返すってアホなコードになってるよ。将来構造体をサポートしたとき見直そう。
動作テスト
どうかな。
~/myc$ myc o23.myc ~/myc$ ./o23 p + 0 = 0000000000c49260 p + 1 = 0000000000c49264 p + 2 = 0000000000c49268 p + 3 = 0000000000c4926c p + 4 = 0000000000c49270 p + 5 = 0000000000c49274 p + 6 = 0000000000c49278 p + 7 = 0000000000c4927c p + 8 = 0000000000c49280 p + 9 = 0000000000c49284 0 + p = 0000000000c49260 1 + p = 0000000000c49264 2 + p = 0000000000c49268 3 + p = 0000000000c4926c 4 + p = 0000000000c49270 5 + p = 0000000000c49274 6 + p = 0000000000c49278 7 + p = 0000000000c4927c 8 + p = 0000000000c49280 9 + p = 0000000000c49284 ~/myc$
４つずつ増えてる。大丈夫そうだね。調子に乗ってもういっちょ行ってみるよ。
// int*型+int型 extern void *malloc(size_t size); extern void free(void *ptr); extern int puts(char *s); int main() { int *p = malloc(10*4); for(int i = 0; i < 10; i = i + 1) *(p+i) = i; for(int i = 0; i < 10; i = i + 1) printf("*(p + %d) = %d\n", i, *(p+i)); free(p); }
前回の間接参照演算子との組み合わせだよ。
~/myc$ myc o24.myc ~/myc$ ./o24 *(p + 0) = 0 *(p + 1) = 1 *(p + 2) = 2 *(p + 3) = 3 *(p + 4) = 4 *(p + 5) = 5 *(p + 6) = 6 *(p + 7) = 7 *(p + 8) = 8 *(p + 9) = 9 ~/myc$
おお、動いた。次回は変数宣言の見直しだな。void型変数を弾くようにしないといけないよ。
