add loop control statements

bootstrap/emit.cc

@@ -62,6 +62,7 @@ std::any EmitVisitor::visitStatement(xlangParser::StatementContext *ctx) {
   if (ctx->While()) {
     int block = blockcount++;
 
+    loopstack.push_back(block);
     output << "@while" << block << "_expr" << std::endl;
     tmpcount = 0;
     visitCondition(ctx->condition());
@@ -71,8 +72,17 @@ std::any EmitVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     visitBlock(ctx->block(0));
     output << "  jmp @while" << block << "_expr" << std::endl;
     output << "@while" << block << "_end" << std::endl;
+    loopstack.pop_back();
     return {};
   }
+  if (ctx->Break()) {
+    output << "  jmp @while" << loopstack.back() << "_end" << std::endl;
+    output << "@dead" << blockcount++ << std::endl;
+  }
+  if (ctx->Continue()) {
+    output << "  jmp @while" << loopstack.back() << "_expr" << std::endl;
+    output << "@dead" << blockcount++ << std::endl;
+  }
   if (ctx->Return()) {
     tmpcount = 0;
     visitValue(ctx->value());

bootstrap/emit.hh

@@ -9,9 +9,10 @@ namespace xlang {
 
 class EmitVisitor : public xlangBaseVisitor {
   std::ofstream output;
-  int blockcount;
-  int tmpcount;
+  size_t blockcount;
+  size_t tmpcount;
   std::string last;
+  std::vector<size_t> loopstack;
 
   std::string tmp();
 

bootstrap/error.cc

@@ -29,6 +29,11 @@ void ErrorListener::duplicateFunction(antlr4::Token *token,
              "duplicate function '" + name + "'");
 }
 
+void ErrorListener::loopControlWithoutLoop(antlr4::Token *token) {
+  printError(token->getLine(), token->getCharPositionInLine(),
+             "loop control statement without loop");
+}
+
 void ErrorListener::shadowedVariable(antlr4::Token *token,
                                      const std::string &name) {
   printError(token->getLine(), token->getCharPositionInLine(),

bootstrap/error.hh

@@ -19,6 +19,7 @@ class ErrorListener : public antlr4::BaseErrorListener {
 
   [[noreturn]] void compilerError(const std::string &file, size_t line);
   void duplicateFunction(antlr4::Token *token, const std::string &name);
+  void loopControlWithoutLoop(antlr4::Token *token);
   void shadowedVariable(antlr4::Token *token, const std::string &name);
   void syntaxError(antlr4::Recognizer *recognizer,
                    antlr4::Token *offendingSymbol, size_t line,

bootstrap/typecheck.cc

@@ -14,7 +14,7 @@ std::string typeToString(Type type) {
 }
 
 TypeCheckVisitor::TypeCheckVisitor(ErrorListener &errorlistener)
-    : errorlistener{errorlistener} {}
+    : errorlistener{errorlistener}, loopcount{0} {}
 
 std::any TypeCheckVisitor::visitFile(xlangParser::FileContext *ctx) {
   for (auto function : ctx->function()) {
@@ -103,12 +103,30 @@ std::any TypeCheckVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     if (type != Type::Boolean) {
       errorlistener.typeMismatch(condition->getStart(), Type::Boolean, type);
     }
+    if (ctx->While()) {
+      loopcount++;
+    }
     visitBlock(ctx->block(0));
+    if (ctx->While()) {
+      loopcount--;
+    }
     if (ctx->Else()) {
       visitBlock(ctx->block(1));
     }
     return {};
   }
+  if (ctx->Break()) {
+    if (!loopcount) {
+      errorlistener.loopControlWithoutLoop(ctx->Break()->getSymbol());
+    }
+    return {};
+  }
+  if (ctx->Continue()) {
+    if (!loopcount) {
+      errorlistener.loopControlWithoutLoop(ctx->Continue()->getSymbol());
+    }
+    return {};
+  }
   if (ctx->Return()) {
     auto type = std::any_cast<Type>(visitValue(ctx->value()));
 

bootstrap/typecheck.hh

@@ -28,6 +28,7 @@ class TypeCheckVisitor : public xlangBaseVisitor {
   std::unordered_map<std::string, Signature> signatures;
   Type returntype;
   Scope<Type> scope;
+  size_t loopcount;
 
  public:
   TypeCheckVisitor(ErrorListener &errorlistener);

bootstrap/xlang.g4

@@ -11,6 +11,8 @@ statement : Identifier Define value Semicolon
           | Identifier Assign value Semicolon
           | If condition block (Else block)?
           | While condition block
+          | Break Semicolon
+          | Continue Semicolon
           | Return value Semicolon
           | Print value Semicolon
           ;
@@ -49,6 +51,8 @@ TypeBoolean : 'bool';
 If  : 'if';
 Else  : 'else';
 While : 'while';
+Break : 'break';
+Continue  : 'continue';
 Return  : 'return';
 Print : 'print';
 And : 'and';

test/meson.build

@@ -19,3 +19,12 @@ custom_target('fib.ssa',
 executable('fib',
   sources : qbe.process(xc.process('fib.x')),
   link_args : ['-static'])
+
+# XXX why is this needed?
+custom_target('sieve.ssa',
+  command : ['cp', '@INPUT@', '@OUTPUT@'],
+  input : xc.process('sieve.x'),
+  output : '@BASENAME@.ssa')
+executable('sieve',
+  sources : qbe.process(xc.process('sieve.x')),
+  link_args : ['-static'])

test/sieve.x

@@ -0,0 +1,19 @@
+main() : int {
+  print 2;
+  i := 3;
+  while i < 100 {
+    composite := false;
+    j := 3;
+    while j < i {
+      if i % j == 0 {
+        composite = true;
+        break;
+      }
+      j = j + 2;
+    }
+    if not composite {
+      print i;
+    }
+    i = i + 2;
+  }
+}