From 17157979639ab081b43fec714c3c08e47dcd8c72 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Thu, 15 Aug 2019 13:48:41 +0900
Subject: [PATCH] Add break statement

---
 chibicc.h      |  3 +++
 codegen.c      |  4 ++--
 parse.c        | 22 ++++++++++++++++++++++
 test/control.c |  5 +++++
 tokenize.c     |  2 +-
 5 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/chibicc.h b/chibicc.h
index 48b511c..350243c 100644
--- a/chibicc.h
+++ b/chibicc.h
@@ -137,6 +137,9 @@ struct Node {
   Node *init;
   Node *inc;
 
+  // "break" label
+  char *brk_label;
+
   // Block or statement expression
   Node *body;
 
diff --git a/codegen.c b/codegen.c
index b76377f..0d1f0ab 100644
--- a/codegen.c
+++ b/codegen.c
@@ -354,13 +354,13 @@ static void gen_stmt(Node *node) {
     if (node->cond) {
       gen_expr(node->cond);
       println("  cmp $0, %%rax");
-      println("  je  .L.end.%d", c);
+      println("  je %s", node->brk_label);
     }
     gen_stmt(node->then);
     if (node->inc)
       gen_expr(node->inc);
     println("  jmp .L.begin.%d", c);
-    println(".L.end.%d:", c);
+    println("%s:", node->brk_label);
     return;
   }
   case ND_BLOCK:
diff --git a/parse.c b/parse.c
index d0c0d2c..23286e6 100644
--- a/parse.c
+++ b/parse.c
@@ -77,6 +77,9 @@ static Var *current_fn;
 static Node *gotos;
 static Node *labels;
 
+// Current "goto" jump target.
+static char *brk_label;
+
 static bool is_typename(Token *tok);
 static Type *typespec(Token **rest, Token *tok, VarAttr *attr);
 static Type *enum_specifier(Token **rest, Token *tok);
@@ -588,6 +591,7 @@ static bool is_typename(Token *tok) {
 //      | "for" "(" expr-stmt expr? ";" expr? ")" stmt
 //      | "while" "(" expr ")" stmt
 //      | "goto" ident ";"
+//      | "break" ";"
 //      | ident ":" stmt
 //      | "{" compound-stmt
 //      | expr-stmt
@@ -620,6 +624,9 @@ static Node *stmt(Token **rest, Token *tok) {
 
     enter_scope();
 
+    char *brk = brk_label;
+    brk_label = node->brk_label = new_unique_name();
+
     if (is_typename(tok)) {
       Type *basety = typespec(&tok, tok, NULL);
       node->init = declaration(&tok, tok, basety);
@@ -636,7 +643,9 @@ static Node *stmt(Token **rest, Token *tok) {
     tok = skip(tok, ")");
 
     node->then = stmt(rest, tok);
+
     leave_scope();
+    brk_label = brk;
     return node;
   }
 
@@ -645,7 +654,11 @@ static Node *stmt(Token **rest, Token *tok) {
     tok = skip(tok->next, "(");
     node->cond = expr(&tok, tok);
     tok = skip(tok, ")");
+
+    char *brk = brk_label;
+    brk_label = node->brk_label = new_unique_name();
     node->then = stmt(rest, tok);
+    brk_label = brk;
     return node;
   }
 
@@ -658,6 +671,15 @@ static Node *stmt(Token **rest, Token *tok) {
     return node;
   }
 
+  if (equal(tok, "break")) {
+    if (!brk_label)
+      error_tok(tok, "stray break");
+    Node *node = new_node(ND_GOTO, tok);
+    node->unique_label = brk_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 9baa2e2..24a8eff 100644
--- a/test/control.c
+++ b/test/control.c
@@ -42,6 +42,11 @@ int main() {
 
   ASSERT(1, ({ typedef int foo; goto foo; foo:; 1; }));
 
+  ASSERT(3, ({ int i=0; for(;i<10;i++) { if (i == 3) break; } i; }));
+  ASSERT(4, ({ int i=0; while (1) { if (i++ == 3) break; } i; }));
+  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; }));
+
   printf("OK\n");
   return 0;
 }
diff --git a/tokenize.c b/tokenize.c
index 7b570c0..6729fe3 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",
+    "enum", "static", "goto", "break",
   };
 
   for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++)
-- 
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