From cb813c68cc21991d461d930fe1ee60364ca1d172 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Thu, 27 Aug 2020 21:59:19 +0900
Subject: [PATCH] Add continue statement

---
 chibicc.h      |  3 ++-
 codegen.c      |  1 +
 parse.c        | 21 ++++++++++++++++++++-
 test/control.c |  7 +++++++
 tokenize.c     |  2 +-
 5 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/chibicc.h b/chibicc.h
index 350243c..c8194db 100644
--- a/chibicc.h
+++ b/chibicc.h
@@ -137,8 +137,9 @@ struct Node {
   Node *init;
   Node *inc;
 
-  // "break" label
+  // "break" and "continue" labels
   char *brk_label;
+  char *cont_label;
 
   // Block or statement expression
   Node *body;
diff --git a/codegen.c b/codegen.c
index 0d1f0ab..8b2fd7e 100644
--- a/codegen.c
+++ b/codegen.c
@@ -357,6 +357,7 @@ static void gen_stmt(Node *node) {
       println("  je %s", node->brk_label);
     }
     gen_stmt(node->then);
+    println("%s:", node->cont_label);
     if (node->inc)
       gen_expr(node->inc);
     println("  jmp .L.begin.%d", c);
diff --git a/parse.c b/parse.c
index 23286e6..1a37e78 100644
--- a/parse.c
+++ b/parse.c
@@ -77,8 +77,9 @@ static Var *current_fn;
 static Node *gotos;
 static Node *labels;
 
-// Current "goto" jump target.
+// Current "goto" and "continue" jump targets.
 static char *brk_label;
+static char *cont_label;
 
 static bool is_typename(Token *tok);
 static Type *typespec(Token **rest, Token *tok, VarAttr *attr);
@@ -592,6 +593,7 @@ static bool is_typename(Token *tok) {
 //      | "while" "(" expr ")" stmt
 //      | "goto" ident ";"
 //      | "break" ";"
+//      | "continue" ";"
 //      | ident ":" stmt
 //      | "{" compound-stmt
 //      | expr-stmt
@@ -625,7 +627,9 @@ static Node *stmt(Token **rest, Token *tok) {
     enter_scope();
 
     char *brk = brk_label;
+    char *cont = cont_label;
     brk_label = node->brk_label = new_unique_name();
+    cont_label = node->cont_label = new_unique_name();
 
     if (is_typename(tok)) {
       Type *basety = typespec(&tok, tok, NULL);
@@ -646,6 +650,7 @@ static Node *stmt(Token **rest, Token *tok) {
 
     leave_scope();
     brk_label = brk;
+    cont_label = cont;
     return node;
   }
 
@@ -656,9 +661,14 @@ static Node *stmt(Token **rest, Token *tok) {
     tok = skip(tok, ")");
 
     char *brk = brk_label;
+    char *cont = cont_label;
     brk_label = node->brk_label = new_unique_name();
+    cont_label = node->cont_label = new_unique_name();
+
     node->then = stmt(rest, tok);
+
     brk_label = brk;
+    cont_label = cont;
     return node;
   }
 
@@ -680,6 +690,15 @@ static Node *stmt(Token **rest, Token *tok) {
     return node;
   }
 
+  if (equal(tok, "continue")) {
+    if (!cont_label)
+      error_tok(tok, "stray continue");
+    Node *node = new_node(ND_GOTO, tok);
+    node->unique_label = cont_label;
+    *rest = skip(tok->next, ";");
+    return node;
+  }
+
   if (tok->kind == TK_IDENT && equal(tok->next, ":")) {
     Node *node = new_node(ND_LABEL, tok);
     node->label = strndup(tok->loc, tok->len);
diff --git a/test/control.c b/test/control.c
index 24a8eff..a38734c 100644
--- a/test/control.c
+++ b/test/control.c
@@ -47,6 +47,13 @@ int main() {
   ASSERT(3, ({ int i=0; for(;i<10;i++) { for (;;) break; if (i == 3) break; } i; }));
   ASSERT(4, ({ int i=0; while (1) { while(1) break; if (i++ == 3) break; } i; }));
 
+  ASSERT(10, ({ int i=0; int j=0; for (;i<10;i++) { if (i>5) continue; j++; } i; }));
+  ASSERT(6, ({ int i=0; int j=0; for (;i<10;i++) { if (i>5) continue; j++; } j; }));
+  ASSERT(10, ({ int i=0; int j=0; for(;!i;) { for (;j!=10;j++) continue; break; } j; }));
+  ASSERT(11, ({ int i=0; int j=0; while (i++<10) { if (i>5) continue; j++; } i; }));
+  ASSERT(5, ({ int i=0; int j=0; while (i++<10) { if (i>5) continue; j++; } j; }));
+  ASSERT(11, ({ int i=0; int j=0; while(!i) { while (j++!=10) continue; break; } j; }));
+
   printf("OK\n");
   return 0;
 }
diff --git a/tokenize.c b/tokenize.c
index 6729fe3..4546b40 100644
--- a/tokenize.c
+++ b/tokenize.c
@@ -125,7 +125,7 @@ static bool is_keyword(Token *tok) {
   static char *kw[] = {
     "return", "if", "else", "for", "while", "int", "sizeof", "char",
     "struct", "union", "short", "long", "void", "typedef", "_Bool",
-    "enum", "static", "goto", "break",
+    "enum", "static", "goto", "break", "continue",
   };
 
   for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++)
-- 
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