中間代碼生成器?

一、實驗目的

掌握中間代碼生成器的構造原理和編程方法。

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二、實驗內容

用自頂向下方法或Yacc進行語法分析的基礎上，編寫一個中間代碼生成程序。（見教材附錄 A.1，p394）

program ???? → block

block ??? →?? { decls stmts }

decls? →?? decls decl | e

decl?? →?? type id ;

type?? →?? type [num]?? //數組可以不做

?| basic??????? //四種基本數據類型 int | float | char | bool

stmts ??? →　stmts stmt | e

? ?????stmt ????? →?? id= expr ;

???????????????????? ?? |????? if ( bool ) stmt

??????????????????????????? |????? if ( bool) stmt else stmt

|????? while (bool) stmt

|????? do stmt while (bool ) ;

|????? break ;??? //break可以不做

|????? block

bool ???? ??→? bool || join? |? join

join???? →?? join? && equality | equality

equality? →? equality == rel? |? equality != rel? |? rel

rel????? →? expr < expr

|??? expr <= expr

| ? ??expr > expr

| ? ??expr >= expr

| ? ??expr

expr ???? → expr + term

| ??? expr - term

| ??? term

term ???? → term * unary

?| ? term / unary

| ??? unary

????? unary? →? !unary? |? - unary? |? factor

factor???? → ( expr ) | id| num　

。

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三、實驗要求

１．個人完成，提交實驗報告。

２．實驗的結果為：生成中間代碼 （三地址碼）

{

a=10;

x = b - c;

y = a * x;

z = x * d;

abcd = a + x +y;

if(a>10)

a=a+1;

a=a+2;

}

??? 實驗結果生成的代碼片段

??? 0:? a =? 10

??? 1:? t0 = b - c

??? 2:? x =? t0

??? 3:? t1 = a * x

??? 4:? y =? t1

??? 5:? t2 = x * d

??? 6:? z =? t2

??? 7:? t3 = a + x

??? 8:? t4 = t3 + y

??? 9:? abcd =? t4

?? 10:? if a > 10 goto 12

?? 11:? goto 14

?? 12:? t5 = a + 1

?? 13:? a =? t5

?? 14:? t6 = a + 2

?? 15:? a =? t6

個人對于本次中間代碼生成器-編譯實驗的心得：

View Code #define YYSTYPE node：定義符號棧屬性結點類型typedef struct node{instrlist *truelist, *falselist, *nextlist;//相當于有一個 正確鏈表與 錯誤鏈表 每個鏈表結點都有個值char addr[256];// 地址字段 存放具體結點的內容比如 a 8 10 等char lexeme[256];//字符串指端char oper[3];//操作符字段 具體存放操作符對應的字符串int instr; //是否要回填指示 具體內容是行號 }node;int main(){list = newcodelist();//申請一個內存空間給list// int linecnt, capacity; 行數 與 最大行數// int temp_index; // char **code; 總代碼 freopen("test.in", "rt+", stdin);freopen("test.out", "wt+", stdout);//打開文件 yyparse();print(list);fclose(stdin);//關閉文件 fclose(stdout);//關閉文件return 0;}int gen_if(codelist *dst, node left, char* op, node right){sprintf(tmp, "if %s %s %s goto", left.addr, op, right.addr);//第一個字符串 操作符 第二個字符串 Gen(dst, tmp); //將tmp的內容存放到 總字符串 list的code字段當中return 0;} int Gen(codelist *dst, char *str) //輸入 第一個參數為 list 第二個參數是 總字符串 tmp[1024] { //目標是 將tmp的內容存放到 總字符串 list的code字段當中if (dst->linecnt >= dst->capacity){dst->capacity += 1024;dst->code = (char**)realloc(dst->code, sizeof(char*)*dst->capacity);if (dst->code == NULL){printf("short of memeory\n");return 0;}}dst->code[dst->linecnt] = (char*)malloc(strlen(str)+20); //申請一個內存空間存放中間字符串 strcpy(dst->code[dst->linecnt], str); //字符串復制 dst->linecnt++; //行號加1return 0;}int backpatch(codelist *dst, instrlist *list, int instrno) //總代碼 dst 錯誤列表list 錯誤的指向行數 {if (list!=NULL) //如果錯誤的列表不為空 {listele *p=list->first; char tmp[20];sprintf(tmp, " %d", instrno); 取出一個while (p!=NULL){if (p->instrno<dst->linecnt)strcat(dst->code[p->instrno], tmp); //錯誤列表：1 2 3 4 假設都指向instrno=6 那么將6轉化為字符串tmp//再添加到每個字符串的末尾 p=p->next;}}return 0;}// int linecnt, capacity; 行數 與 最大行數// int temp_index; // char **code;

重點是對課上的回填技術，還有

棧中的可能屬性類別也就是node結點的屬性種類，還有的是全局變量list使用的結點除了行號，最大行號，還有就是三地址碼存放的chor **類型的code。

jia.l

View Code %{#include "jia.tab.h" %} delim [ \t\n\r] ws {delim}+ letter [A-Za-z] digit [0-9] id {letter}({letter}|{digit})* integer {digit}+ exponent E[+-]?{integer} number {integer}{exponent}? real integer(\.integer)?{exponent}? %option noyywrap %% if { return( IF ); } else { return( ELSE ); } while { return( WHILE ); } do { return( DO ); } for { return( FOR ); } switch { return( SWITCH ); } case { return( CASE ); } default { return( DEFAULT ); } break { return( BREAK ); } true { return( TRUE ); } false { return( FALSE ); } int { return( INT ); } long { return( LONG ); } char { return( CHAR ); } bool { return( BOOL ); } float { return( FLOAT ); } double { return( DOUBLE ); } "&&" { return( AND ); } "||" { return( OR ); } "!" { return( '!'); } "<"|"<="|">"|">="|"!="|"==" { filloperator(&yylval, yytext); return( REL); } "++" { return( INC ); } "--" { return( DEC ); } "+" { return( '+' ); } "-" { return( '-' ); } "*" { return( '*' ); } "/" { return( '/' ); } "=" { return( '=' ); } "{" { return( '{' ); } "}" { return( '}' ); } "[" { return( '[' ); } "]" { return( ']' ); } "(" { return( '(' ); } ")" { return( ')' ); }";" { return( ';' ); } {ws} { } {id} { filllexeme(&yylval, yytext); return( ID ); } {number} { filllexeme(&yylval, yytext); return( NUMBER ); } {real} { filllexeme(&yylval, yytext); return( REAL ); } %%

jia.y

View Code %{#include "xu.h"#define YYSTYPE node#include "jia.tab.h"int yyerror();int yyerror(char* msg);extern int yylex();codelist* list; %} %token BASIC NUMBER REAL ID TRUE FALSE %token INT LONG CHAR BOOL FLOAT DOUBLE %token REL %token IF ELSE WHILE DO BREAK FOR SWITCH CASE DEFAULT %token OR AND %left OR %left AND %right '!' %left '+' '-' %left '*' '/' %right UMINUS %right INC DEC %%program : block { };block : '{' decls statementlist '}' { };decls : decls decl { }| { };decl : type ID ';' { };type : type '[' NUMBER ']' { }| BASIC { };statementlist :statementlist M statement { backpatch(list, $1.nextlist, $2.instr);$$.nextlist = $3.nextlist; }| statement { $$.nextlist = $1.nextlist; };statement :IF '(' boolean ')' M statement ELSE N M statement { backpatch(list, $3.truelist, $5.instr);backpatch(list, $3.falselist, $9.instr);$6.nextlist = merge($6.nextlist, $8.nextlist);$$.nextlist = merge($6.nextlist, $10.nextlist); } | IF '(' boolean ')' M statement { backpatch(list, $3.truelist, $5.instr);$$.nextlist = merge($3.falselist, $6.nextlist); }| WHILE M '(' boolean ')' M statement { backpatch(list, $7.nextlist, $2.instr);backpatch(list, $4.truelist, $6.instr);$$.nextlist = $4.falselist;gen_goto(list, $2.instr); }| DO M statement M WHILE '(' boolean ')' M ';' { backpatch(list, $3.nextlist, $4.instr);backpatch(list, $7.truelist, $9.instr);$$.nextlist = $7.falselist;gen_goto(list, $2.instr); }| FOR '(' assignment ';' M boolean ';' M assignment ')' N M statement { backpatch(list, $6.truelist, $12.instr);backpatch(list, $11.nextlist, $5.instr);backpatch(list, $13.nextlist, $8.instr);$$.nextlist = $6.falselist;gen_goto(list, $8.instr); }| BREAK ';' { }| '{' statementlist '}' { $$.nextlist = $2.nextlist; } | assignment ';' { $$.nextlist = NULL; };assignment : ID '=' boolean { copyaddr(&$1, $1.lexeme); gen_assignment(list, $1, $3); };loc : loc '[' boolean ']' { }| ID { copyaddr(&$$, $1.lexeme); };boolean : boolean OR M boolean { backpatch(list, $1.falselist, $3.instr);$$.truelist = merge($1.truelist, $4.truelist);$$.falselist = $4.falselist; }| boolean AND M boolean { backpatch(list, $1.truelist, $3.instr);$$.truelist = $4.truelist;$$.falselist = merge($1.falselist, $4.falselist); }| '!' boolean { $$.truelist = $1.falselist;$$.falselist = $1.truelist; }| '(' boolean ')' { $$.truelist = $1.truelist; $$.falselist = $1.falselist; }| expression REL expression { $$.truelist = new_instrlist(nextinstr(list));$$.falselist = new_instrlist(nextinstr(list)+1);gen_if(list, $1, $2.oper, $3);gen_goto_blank(list); }| TRUE { copyaddr(&$$, "TRUE");gen_goto_blank(list); }| FALSE { copyaddr(&$$, "FALSE");gen_goto_blank(list); }| expression { copyaddr_fromnode(&$$, $1); };M : { $$.instr = nextinstr(list); };N : { $$.nextlist = new_instrlist(nextinstr(list));gen_goto_blank(list); };expression : expression '+' expression { new_temp(&$$, get_temp_index(list)); gen_3addr(list, $$, $1, "+", $3); }| expression '-' expression { new_temp(&$$, get_temp_index(list)); gen_3addr(list, $$, $1, "-", $3); }| expression '*' expression { new_temp(&$$, get_temp_index(list)); gen_3addr(list, $$, $1, "*", $3); }| expression '/' expression { new_temp(&$$, get_temp_index(list)); gen_3addr(list, $$, $1, "/", $3); }| '-' expression %prec UMINUS { new_temp(&$$, get_temp_index(list)); gen_2addr(list, $$, "-", $2); }| loc { copyaddr_fromnode(&$$, $1); }| NUMBER { copyaddr(&$$, $1.lexeme); }| REAL { copyaddr(&$$, $1.lexeme); };%%int yyerror(char* msg) {printf("\nERROR with message: %s\n", msg);return 0; }int main() {list = newcodelist(); //申請一個內存空間給list // int linecnt, capacity; // int temp_index; // char **code;freopen("test.in", "rt+", stdin);freopen("test.out", "wt+", stdout); //打開文件 yyparse();print(list);fclose(stdin); //關閉文件 fclose(stdout); //關閉文件return 0; }

xu.h

View Code #ifndef CP_H #define CP_H#include <stdio.h> #include <string.h> #include <malloc.h>typedef struct listele {int instrno;struct listele *next; }listele;listele* new_listele(int no){listele* p = (listele*)malloc(sizeof(listele));p->instrno = no;p->next = NULL;return p;}typedef struct instrlist {listele *first,*last; }instrlist;instrlist* new_instrlist(int instrno){instrlist* p = (instrlist*)malloc(sizeof(instrlist));p->first = p->last = new_listele(instrno);return p;}instrlist* merge(instrlist *list1, instrlist *list2){instrlist *p;if (list1 == NULL) p = list2;else{if (list2!=NULL){if (list1->last == NULL){list1->first = list2->first;list1->last =list2->last;}else list1->last->next = list2->first;list2->first = list2->last = NULL;free(list2);}p = list1;}return p;}typedef struct node {instrlist *truelist, *falselist, *nextlist;char addr[256];char lexeme[256];char oper[3];int instr; }node;int filloperator(node *dst, char *src){strcpy(dst->oper, src);return 0;} int filllexeme(node *dst, char *yytext){strcpy(dst->lexeme, yytext);return 0;}int copyaddr(node *dst, char *src){strcpy(dst->addr, src);return 0;}int new_temp(node *dst, int index){sprintf(dst->addr, "t%d", index);return 0;}int copyaddr_fromnode(node *dst, node src){strcpy(dst->addr, src.addr);return 0;}typedef struct codelist {int linecnt, capacity;int temp_index;char **code; }codelist;codelist* newcodelist(){codelist* p = (codelist*)malloc(sizeof(codelist));p->linecnt = 0;p->capacity = 1024;p->temp_index = 0;p->code = (char**)malloc(sizeof(char*)*1024);return p;}int get_temp_index(codelist* dst){return dst->temp_index++;}int nextinstr(codelist *dst) { return dst->linecnt; }int Gen(codelist *dst, char *str){if (dst->linecnt >= dst->capacity){dst->capacity += 1024;dst->code = (char**)realloc(dst->code, sizeof(char*)*dst->capacity);if (dst->code == NULL){printf("short of memeory\n");return 0;}}dst->code[dst->linecnt] = (char*)malloc(strlen(str)+20);strcpy(dst->code[dst->linecnt], str);dst->linecnt++;return 0;}char tmp[1024];int gen_goto_blank(codelist *dst){sprintf(tmp, "goto");Gen(dst, tmp);return 0;}int gen_goto(codelist *dst, int instrno){sprintf(tmp, "goto %d", instrno);Gen(dst, tmp);return 0;}int gen_if(codelist *dst, node left, char* op, node right){sprintf(tmp, "if %s %s %s goto", left.addr, op, right.addr);Gen(dst, tmp);return 0;}int gen_1addr(codelist *dst, node left, char* op){sprintf(tmp, "%s %s", left.addr, op);Gen(dst, tmp);return 0;}int gen_2addr(codelist *dst, node left, char* op, node right){sprintf(tmp, "%s = %s %s", left.addr, op, right.addr);Gen(dst, tmp);return 0;}int gen_3addr(codelist *dst, node left, node op1, char* op, node op2){sprintf(tmp, "%s = %s %s %s", left.addr, op1.addr, op, op2.addr);Gen(dst, tmp);return 0;}int gen_assignment(codelist *dst, node left, node right){gen_2addr(dst, left, "", right);return 0;}int backpatch(codelist *dst, instrlist *list, int instrno){if (list!=NULL){listele *p=list->first;char tmp[20];sprintf(tmp, " %d", instrno);while (p!=NULL){if (p->instrno<dst->linecnt)strcat(dst->code[p->instrno], tmp);p=p->next;}}return 0;}int print(codelist* dst){int i;for (i=0; i < dst->linecnt; i++)printf("%5d: %s\n", i, dst->code[i]);return 0;}#endif

test.in

View Code {a=10; x = b - c; y = a * x; z = x * d; abcd = a + x +y; if(a>10) a=a+1; a=a+2; while(a>0) a=a-1; b=b+1; }

?最終老師給的代碼暫未公開

課件

轉載于:https://www.cnblogs.com/xjx-user/archive/2012/12/16/2820682.html

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