Adding $unreachable

resources/testfragments/super_simple2.c3

@@ -2,19 +2,18 @@ module baz;
 import gen;
 
 extern func int printf(char *hello, ...);
+extern func void blurg();
 
 public func void runBaz()
 {
-    int x = printf("Baz func\n");
-    int y = printf("FOek");
 
-    assert(x > 0 && y > 0);
+    int i = printf("hello");
 
-    int z = printf("Foefe\n");
-    x = printf("Baz func\n");
-    y = printf("FOek");
+    if (i > 0) blurg();
 
-    assert(x > 0 && y > 0 && printf("Fejei") > 0);
+    if (i > 0) return;
+
+    $unreachable;
 
 
 }

src/compiler/ast.c

@@ -1085,6 +1085,9 @@ static void fprint_ast_recursive(Context *context, FILE *file, Ast *ast, int ind
 		case AST_NOP_STMT:
 			DUMP("(nop)");
 			return;
+		case AST_UNREACHABLE_STMT:
+			DUMP("(unreachable)");
+			return;
 		case AST_VOLATILE_STMT:
 			DUMP("(volatile");
 			DUMPAST(ast->volatile_stmt);

src/compiler/enums.h

@@ -76,6 +76,7 @@ typedef enum
 	AST_RETURN_STMT,
 	AST_SWITCH_STMT,
 	AST_NEXT_STMT,
+	AST_UNREACHABLE_STMT,
 	AST_VOLATILE_STMT,
 	AST_WHILE_STMT,
 	AST_SCOPED_STMT,
@@ -412,6 +413,7 @@ typedef enum
 	TOKEN_TRY,
 	TOKEN_TYPEDEF,
 	TOKEN_UNION,
+	TOKEN_CT_UNREACHABLE,
 	TOKEN_UNTIL,
 	TOKEN_VAR,              // Reserved
 	TOKEN_VOLATILE,

src/compiler/llvm_codegen_stmt.c

@@ -847,6 +847,17 @@ static inline void gencontext_emit_assert_stmt(GenContext *context, Ast *ast)
 	gencontext_emit_assume(context, ast->assert_stmt.expr);
 }
 
+static inline void gencontext_emit_unreachable_stmt(GenContext *context, Ast *ast)
+{
+	// TODO emit message
+	gencontext_emit_call_intrinsic(context, trap_intrinsic_id, NULL, 0, NULL, 0);
+	LLVMBuildUnreachable(context->builder);
+	LLVMBasicBlockRef block = gencontext_create_free_block(context, "unreachable_block");
+	context->current_block = NULL;
+	context->current_block_is_target = false;
+	gencontext_emit_block(context, block);
+}
+
 void gencontext_emit_expr_stmt(GenContext *context, Ast *ast)
 {
 	if (ast->expr_stmt->failable)
@@ -1003,13 +1014,15 @@ void gencontext_emit_stmt(GenContext *context, Ast *ast)
 		case AST_CT_ELSE_STMT:
 		case AST_CT_FOR_STMT:
 		case AST_CT_SWITCH_STMT:
+		case AST_CASE_STMT:
+		case AST_DEFAULT_STMT:
 			UNREACHABLE
 		case AST_SWITCH_STMT:
 			gencontext_emit_switch(context, ast);
 			break;
-		case AST_CASE_STMT:
-		case AST_DEFAULT_STMT:
-			TODO
+		case AST_UNREACHABLE_STMT:
+			gencontext_emit_unreachable_stmt(context, ast);
+			break;
 		case AST_VOLATILE_STMT:
 			TODO
 	}

src/compiler/parse_stmt.c

@@ -6,6 +6,8 @@
 #include "parser_internal.h"
 
 
+Ast *parse_unreachable_stmt(Context *context);
+
 #pragma mark --- Internal functions
 
 
@@ -913,6 +915,8 @@ Ast *parse_stmt(Context *context)
 			return parse_ct_for_stmt(context);
 		case TOKEN_VOLATILE:
 			return parse_volatile_stmt(context);
+		case TOKEN_CT_UNREACHABLE:
+			return parse_unreachable_stmt(context);
 		case TOKEN_STAR:
 		case TOKEN_AMP:
 		case TOKEN_INTEGER:
@@ -1034,6 +1038,14 @@ Ast *parse_stmt(Context *context)
 	UNREACHABLE
 }
 
+Ast *parse_unreachable_stmt(Context *context)
+{
+	Ast *ast = AST_NEW_TOKEN(AST_UNREACHABLE_STMT, context->tok);
+	advance_and_verify(context, TOKEN_CT_UNREACHABLE);
+	TRY_CONSUME_EOS_OR(poisoned_ast);
+	return ast;
+}
+
 Ast *parse_jump_stmt_no_eos(Context *context)
 {
 	switch (context->tok.type)

src/compiler/sema_expr.c

@@ -3395,6 +3395,8 @@ static Ast *ast_copy_from_macro(Context *context, Ast *source)
 			MACRO_COPY_EXPR(ast->try_stmt.decl_expr);
 			MACRO_COPY_AST(ast->try_stmt.body);
 			return ast;
+		case AST_UNREACHABLE_STMT:
+			return ast;
 		case AST_VOLATILE_STMT:
 			TODO
 			return ast;

src/compiler/sema_stmts.c

@@ -178,6 +178,12 @@ static inline bool sema_analyse_return_stmt(Context *context, Ast *statement)
 	return true;
 }
 
+static inline bool sema_analyse_unreachable_stmt(Context *context, Ast *statement)
+{
+	context->current_scope->jump_end = true;
+	return true;
+}
+
 static inline bool sema_analyse_decl_expr_list(Context *context, Expr *expr)
 {
 	assert(expr->expr_kind == EXPR_DECL_LIST);
@@ -1286,6 +1292,11 @@ static inline bool sema_analyse_statement_inner(Context *context, Ast *statement
 	}
 	if (context->current_scope->jump_end && !context->current_scope->allow_dead_code)
 	{
+		if (statement->ast_kind == AST_UNREACHABLE_STMT)
+		{
+			context->current_scope->allow_dead_code = true;
+			return true;
+		}
 		//SEMA_ERROR(statement, "This code will never execute.");
 		context->current_scope->allow_dead_code = true;
 		//return false;
@@ -1341,10 +1352,13 @@ static inline bool sema_analyse_statement_inner(Context *context, Ast *statement
 			return sema_analyse_switch_stmt(context, statement);
 		case AST_NEXT_STMT:
 			return sema_analyse_next_stmt(context, statement);
+		case AST_UNREACHABLE_STMT:
+			return sema_analyse_unreachable_stmt(context, statement);
 		case AST_VOLATILE_STMT:
 			return sema_analyse_volatile_stmt(context, statement);
 		case AST_WHILE_STMT:
 			return sema_analyse_while_stmt(context, statement);
+
 		case AST_CT_ELIF_STMT:
 		case AST_CT_ELSE_STMT:
 			UNREACHABLE

src/compiler/tokens.c

@@ -344,6 +344,8 @@ const char *token_type_to_string(TokenType type)
 			return "$if";
 		case TOKEN_CT_SWITCH:
 			return "$switch";
+		case TOKEN_CT_UNREACHABLE:
+			return "$unreachable";
 		case TOKEN_EOF:
 			return "EOF";
 

test/test_suite/assert/unreachable.c3t

@@ -0,0 +1,36 @@
+
+public func int foo()
+{
+    return 1;
+}
+
+public func void test()
+{
+    int x = foo();
+    if (x > 0) return;
+    $unreachable;
+    x++;
+}
+
+
+// #expect: unreachable.ll
+
+    %x = alloca i32
+    %0 = call i32 @unreachable.foo()
+    store i32 %0, i32* %x
+    %1 = load i32, i32* %x
+    %gt = icmp sgt i32 %1, 0
+    br i1 %gt, label %if.then, label %if.exit
+
+if.then:
+    ret void
+
+if.exit:
+    call void @llvm.trap()
+    unreachable
+
+unreachable_block:
+    %2 = load i32, i32* %x
+    %add = add nsw i32 %2, 1
+    store i32 %add, i32* %x
+    ret void