Print an error message if the runtime couldn't be started (#2431)

This change is handled in generated code and doesn't affect the runtime
itself.

src/libponyc/codegen/codegen.c

@@ -818,6 +818,11 @@ static void init_runtime(compile_t* c)
   param = LLVMGetParam(value, 1);
   LLVMAddAttribute(param, LLVMReadOnlyAttribute);
 #endif
+
+  // i32 puts(i8*)
+  params[0] = c->void_ptr;
+  type = LLVMFunctionType(c->i32, params, 1, false);
+  value = LLVMAddFunction(c->module, "puts", type);
 }
 
 static bool init_module(compile_t* c, ast_t* program, pass_opt_t* opt)
@@ -1422,6 +1427,22 @@ LLVMValueRef codegen_call(compile_t* c, LLVMValueRef fun, LLVMValueRef* args,
   return result;
 }
 
+LLVMValueRef codegen_string(compile_t* c, const char* str, size_t len)
+{
+  LLVMValueRef str_val = LLVMConstStringInContext(c->context, str, (int)len,
+    false);
+  LLVMValueRef g_str = LLVMAddGlobal(c->module, LLVMTypeOf(str_val), "");
+  LLVMSetLinkage(g_str, LLVMPrivateLinkage);
+  LLVMSetInitializer(g_str, str_val);
+  LLVMSetGlobalConstant(g_str, true);
+  LLVMSetUnnamedAddr(g_str, true);
+
+  LLVMValueRef args[2];
+  args[0] = LLVMConstInt(c->i32, 0, false);
+  args[1] = LLVMConstInt(c->i32, 0, false);
+  return LLVMConstInBoundsGEP(g_str, args, 2);
+}
+
 const char* suffix_filename(compile_t* c, const char* dir, const char* prefix,
   const char* file, const char* extension)
 {

src/libponyc/codegen/codegen.h

@@ -296,6 +296,8 @@ LLVMBasicBlockRef codegen_block(compile_t* c, const char* name);
 LLVMValueRef codegen_call(compile_t* c, LLVMValueRef fun, LLVMValueRef* args,
   size_t count, bool setcc);
 
+LLVMValueRef codegen_string(compile_t* c, const char* str, size_t len);
+
 const char* suffix_filename(compile_t* c, const char* dir, const char* prefix,
   const char* file, const char* extension);
 

src/libponyc/codegen/genexe.c

@@ -47,6 +47,9 @@ LLVMValueRef gen_main(compile_t* c, reach_type_t* t_main, reach_type_t* t_env)
 
   codegen_startfun(c, func, NULL, NULL, false);
 
+  LLVMBasicBlockRef start_fail_block = codegen_block(c, "start_fail");
+  LLVMBasicBlockRef post_block = codegen_block(c, "post");
+
   LLVMValueRef args[5];
   args[0] = LLVMGetParam(func, 0);
   LLVMSetValueName(args[0], "argc");
@@ -129,6 +132,21 @@ LLVMValueRef gen_main(compile_t* c, reach_type_t* t_main, reach_type_t* t_env)
   args[1] = LLVMConstInt(c->i32, 1, false);
   LLVMValueRef rc = gencall_runtime(c, "pony_start", args, 2, "");
 
+  LLVMValueRef minus_one = LLVMConstInt(c->i32, (unsigned long long)-1, true);
+  LLVMValueRef start_success = LLVMBuildICmp(c->builder, LLVMIntNE, rc,
+    minus_one, "");
+  LLVMBuildCondBr(c->builder, start_success, post_block, start_fail_block);
+
+  LLVMPositionBuilderAtEnd(c->builder, start_fail_block);
+
+  const char error_msg_str[] = "Error: couldn't initialise runtime!";
+
+  args[0] = codegen_string(c, error_msg_str, sizeof(error_msg_str));
+  gencall_runtime(c, "puts", args, 1, "");
+  LLVMBuildBr(c->builder, post_block);
+
+  LLVMPositionBuilderAtEnd(c->builder, post_block);
+
   // Run primitive finalisers. We create a new main actor as a context to run
   // the finalisers in, but we do not initialise or schedule it.
   if(c->primitives_final != NULL)

src/libponyc/codegen/genreference.c

@@ -507,26 +507,14 @@ LLVMValueRef gen_string(compile_t* c, ast_t* ast)
 
   size_t len = ast_name_len(ast);
 
-  LLVMValueRef args[4];
-  args[0] = LLVMConstInt(c->i32, 0, false);
-  args[1] = LLVMConstInt(c->i32, 0, false);
-
-  LLVMValueRef str = LLVMConstStringInContext(c->context, name, (int)len,
-    false);
-  LLVMValueRef g_str = LLVMAddGlobal(c->module, LLVMTypeOf(str), "");
-  LLVMSetLinkage(g_str, LLVMPrivateLinkage);
-  LLVMSetInitializer(g_str, str);
-  LLVMSetGlobalConstant(g_str, true);
-  LLVMSetUnnamedAddr(g_str, true);
-  LLVMValueRef str_ptr = LLVMConstInBoundsGEP(g_str, args, 2);
-
   reach_type_t* t = reach_type(c->reach, type);
   compile_type_t* c_t = (compile_type_t*)t->c_type;
 
+  LLVMValueRef args[4];
   args[0] = c_t->desc;
   args[1] = LLVMConstInt(c->intptr, len, false);
   args[2] = LLVMConstInt(c->intptr, len + 1, false);
-  args[3] = str_ptr;
+  args[3] = codegen_string(c, name, len);
 
   LLVMValueRef inst = LLVMConstNamedStruct(c_t->structure, args, 4);
   LLVMValueRef g_inst = LLVMAddGlobal(c->module, c_t->structure, "");