break

ccc.h

@@ -85,6 +85,7 @@ typedef enum {
   ND_WHILE,      // "while"
   ND_FOR,        // "for"
   ND_BLOCK,      // { ... }
+  ND_BREAK,      // "break"
   ND_FUNCALL,    // Function call
   ND_EXPR_STMT,  // Expression statement
   ND_STMT_EXPR,  // statement expression

codegen.c

@@ -5,7 +5,8 @@ char *argreg2[] = {"di", "si", "dx", "cx", "r8w", "r9w"};
 char *argreg4[] = {"edi", "esi", "edx", "ecx", "r8d", "r9d"};
 char *argreg8[] = {"rdi", "rsi", "rdx", "rcx", "r8", "r9"};
 
-int labelseq = 0;
+int labelseq;
+int brkseq;
 char *funcname;
 
 void truncate(Type *ty) {
@@ -216,36 +217,52 @@ void gen(Node *node) {
     }
     case ND_WHILE: {
       int seq = labelseq++;
+      int brk = brkseq;
+      brkseq = seq;
+
       printf(".Lbegin%d:\n", seq);
       gen(node->cond);
       printf("  pop rax\n");
       printf("  cmp rax, 0\n");
-      printf("  je  .Lend%d\n", seq);
+      printf("  je  .L.break.%d\n", seq);
       gen(node->then);
       printf("  jmp .Lbegin%d\n", seq);
-      printf(".Lend%d:\n", seq);
+      printf(".L.break.%d:\n", seq);
+
+      brkseq = brk;
       return;
     }
     case ND_FOR: {
       int seq = labelseq++;
+      int brk = brkseq;
+      brkseq = seq;
+
       if (node->init) gen(node->init);
       printf(".Lbegin%d:\n", seq);
       if (node->cond) {
         gen(node->cond);
         printf("  pop rax\n");
         printf("  cmp rax, 0\n");
-        printf("  je  .Lend%d\n", seq);
+        printf("  je  .L.break.%d\n", seq);
       }
       gen(node->then);
       if (node->inc) gen(node->inc);
       printf("  jmp .Lbegin%d\n", seq);
-      printf(".Lend%d:\n", seq);
+      printf(".L.break.%d:\n", seq);
+
+      brkseq = brk;
       return;
     }
     case ND_BLOCK:
     case ND_STMT_EXPR:
       for (Node *n = node->body; n; n = n->next) gen(n);
       return;
+    case ND_BREAK:
+      if (brkseq == 0) {
+        error_tok(node->tok, "stray break");
+      }
+      printf("  jmp .L.break.%d\n", brkseq);
+      return;
     case ND_FUNCALL: {
       int nargs = 0;
       for (Node *arg = node->args; arg; arg = arg->next) {

parse.c

@@ -641,6 +641,7 @@ bool is_typename() {
 //      | "while" "(" expr ")" stmt
 //      | "for" "(" (expr? ";" | declaration) expr? ";" expr? ")" stmt
 //      | "{" stmt* "}"
+//      | "break" ";"
 //      | declaration
 //      | expr ";"
 Node *stmt() {
@@ -709,6 +710,10 @@ Node *stmt() {
     node->body = head.next;
     return node;
   }
+  if (tok = consume("break")) {
+    expect(";");
+    return new_node(ND_BREAK, tok);
+  }
   if (is_typename()) {
     return declaration();
   }

tests

@@ -781,6 +781,11 @@ int main() {
 
   assert(3, ({ int x[2]; x[0]=3; param_decay(x); }), "int x[2]; x[0]=3; param_decay(x);");
 
+  assert(3, ({ int i=0; for(;i<10;i++) { if (i == 3) break; } i; }), "int i=0; for(;i<10;i++) { if (i == 3) break; } i;");
+  assert(4, ({ int i=0; while (1) { if (i++ == 3) break; } i; }), "int i=0; while { if (i == 3) break; } i;");
+  assert(3, ({ int i=0; for(;i<10;i++) { for (;;) break; if (i == 3) break; } i; }), "int i=0; for(;i<10;i++) { if (i == 3) break; } i;");
+  assert(4, ({ int i=0; while (1) { while(1) break; if (i++ == 3) break; } i; }), "int i=0; while { if (i == 3) break; } i;");
+
   printf("OK\n");
   return 0;
 }

tokenize.c

@@ -151,7 +151,7 @@ char *starts_with_reserved(char *p) {
   // Keyword
   static char *kw[] = {"return", "if",     "else",   "while",   "for",   "char",
                        "int",    "sizeof", "struct", "typedef", "short", "long",
-                       "void",   "_Bool",  "enum",   "static"};
+                       "void",   "_Bool",  "enum",   "static",  "break"};
   for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++) {
     int len = strlen(kw[i]);
     if (startswith(p, kw[i]) && !is_alnum(p[len])) {