static declaration_t *current_function = NULL;
static switch_statement_t *current_switch = NULL;
static statement_t *current_loop = NULL;
+static statement_t *current_parent = NULL;
static ms_try_statement_t *current_try = NULL;
static goto_statement_t *goto_first = NULL;
static goto_statement_t *goto_last = NULL;
static translation_unit_t *unit = NULL;
static struct obstack temp_obst;
+#define PUSH_PARENT(stmt) \
+ statement_t *const prev_parent = current_parent; \
+ current_parent = (stmt);
+#define POP_PARENT ((void)(current_parent = prev_parent))
+
static source_position_t null_position = { NULL, 0 };
/* symbols for Microsoft extended-decl-modifier */
size_t size = get_statement_struct_size(kind);
statement_t *res = allocate_ast_zero(size);
- res->base.kind = kind;
+ res->base.kind = kind;
+ res->base.parent = current_parent;
return res;
}
}
}
+static int determine_truth(expression_t const* const cond)
+{
+ return
+ !is_constant_expression(cond) ? 0 :
+ fold_constant(cond) != 0 ? 1 :
+ -1;
+}
+
+static void check_reachable(statement_t *const stmt)
+{
+ if (stmt->base.reachable)
+ return;
+ if (stmt->kind != STATEMENT_DO_WHILE)
+ stmt->base.reachable = true;
+
+ statement_t *last = stmt;
+ statement_t *next;
+ switch (stmt->kind) {
+ case STATEMENT_INVALID:
+ case STATEMENT_EMPTY:
+ case STATEMENT_DECLARATION:
+ case STATEMENT_ASM:
+ next = stmt->base.next;
+ break;
+
+ case STATEMENT_COMPOUND:
+ next = stmt->compound.statements;
+ break;
+
+ case STATEMENT_RETURN:
+ return;
+
+ case STATEMENT_IF: {
+ if_statement_t const* const ifs = &stmt->ifs;
+ int const val = determine_truth(ifs->condition);
+
+ if (val >= 0)
+ check_reachable(ifs->true_statement);
+
+ if (val > 0)
+ return;
+
+ if (ifs->false_statement != NULL) {
+ check_reachable(ifs->false_statement);
+ return;
+ }
+
+ next = stmt->base.next;
+ break;
+ }
+
+ case STATEMENT_SWITCH: {
+ switch_statement_t const *const switchs = &stmt->switchs;
+ expression_t const *const expr = switchs->expression;
+
+ if (is_constant_expression(expr)) {
+ long const val = fold_constant(expr);
+ case_label_statement_t * defaults = NULL;
+ for (case_label_statement_t *i = switchs->first_case; i != NULL; i = i->next) {
+ if (i->expression == NULL) {
+ defaults = i;
+ continue;
+ }
+
+ expression_t *const case_expr = i->expression;
+ if (is_constant_expression(case_expr) &&
+ fold_constant(case_expr) == val) {
+ check_reachable((statement_t*)i);
+ return;
+ }
+ }
+
+ if (defaults != NULL) {
+ check_reachable((statement_t*)defaults);
+ return;
+ }
+ } else {
+ bool has_default = false;
+ for (case_label_statement_t *i = switchs->first_case; i != NULL; i = i->next) {
+ if (i->expression == NULL)
+ has_default = true;
+
+ check_reachable((statement_t*)i);
+ }
+
+ if (has_default)
+ return;
+ }
+
+ next = stmt->base.next;
+ break;
+ }
+
+ case STATEMENT_EXPRESSION: {
+ /* Check for noreturn function call */
+ expression_t const *const expr = stmt->expression.expression;
+ if (expr->kind == EXPR_CALL) {
+ expression_t const *const func = expr->call.function;
+ if (func->kind == EXPR_REFERENCE) {
+ declaration_t const *const decl = func->reference.declaration;
+ if (decl != NULL && decl->modifiers & DM_NORETURN) {
+ return;
+ }
+ }
+ }
+
+ next = stmt->base.next;
+ break;
+ }
+
+ case STATEMENT_CONTINUE: {
+ statement_t *parent = stmt;
+ for (;;) {
+ parent = parent->base.parent;
+ if (parent == NULL) /* continue not within loop */
+ return;
+
+ next = parent;
+ switch (parent->kind) {
+ case STATEMENT_WHILE: goto continue_while;
+ case STATEMENT_DO_WHILE: goto continue_do_while;
+ case STATEMENT_FOR: goto continue_for;
+
+ default: break;
+ }
+ }
+ }
+
+ case STATEMENT_BREAK: {
+ statement_t *parent = stmt;
+ for (;;) {
+ parent = parent->base.parent;
+ if (parent == NULL) /* break not within loop/switch */
+ return;
+
+ switch (parent->kind) {
+ case STATEMENT_SWITCH:
+ case STATEMENT_WHILE:
+ case STATEMENT_DO_WHILE:
+ case STATEMENT_FOR:
+ next = parent->base.next;
+ goto found_break_parent;
+
+ default: break;
+ }
+ }
+found_break_parent:
+ break;
+ }
+
+ case STATEMENT_GOTO:
+ next = stmt->gotos.label->init.statement;
+ if (next == NULL) /* missing label */
+ return;
+ break;
+
+ case STATEMENT_LABEL:
+ next = stmt->label.statement;
+ break;
+
+ case STATEMENT_CASE_LABEL:
+ next = stmt->case_label.statement;
+ break;
+
+ case STATEMENT_WHILE: {
+ while_statement_t const *const whiles = &stmt->whiles;
+ int const val = determine_truth(whiles->condition);
+
+ if (val >= 0)
+ check_reachable(whiles->body);
+
+ if (val > 0)
+ return;
+
+ next = stmt->base.next;
+ break;
+ }
+
+ case STATEMENT_DO_WHILE:
+ next = stmt->do_while.body;
+ break;
+
+ case STATEMENT_FOR: {
+ for_statement_t *const fors = &stmt->fors;
+
+ if (fors->condition_reachable)
+ return;
+ fors->condition_reachable = true;
+
+ expression_t const *const cond = fors->condition;
+ int const val =
+ cond == NULL ? 1 : determine_truth(cond);
+
+ if (val >= 0)
+ check_reachable(fors->body);
+
+ if (val > 0)
+ return;
+
+ next = stmt->base.next;
+ break;
+ }
+
+ case STATEMENT_MS_TRY:
+ case STATEMENT_LEAVE:
+ panic("unimplemented");
+ }
+
+ while (next == NULL) {
+ next = last->base.parent;
+ if (next == NULL) {
+ type_t *const type = current_function->type;
+ assert(is_type_function(type));
+ type_t *const ret = skip_typeref(type->function.return_type);
+ if (warning.return_type &&
+ !is_type_atomic(ret, ATOMIC_TYPE_VOID) &&
+ !is_sym_main(current_function->symbol)) {
+ warningf(&stmt->base.source_position,
+ "control reaches end of non-void function");
+ }
+ return;
+ }
+
+ switch (next->kind) {
+ case STATEMENT_INVALID:
+ case STATEMENT_EMPTY:
+ case STATEMENT_DECLARATION:
+ case STATEMENT_EXPRESSION:
+ case STATEMENT_ASM:
+ case STATEMENT_RETURN:
+ case STATEMENT_CONTINUE:
+ case STATEMENT_BREAK:
+ case STATEMENT_GOTO:
+ case STATEMENT_LEAVE:
+ panic("invalid control flow in function");
+
+ case STATEMENT_COMPOUND:
+ case STATEMENT_IF:
+ case STATEMENT_SWITCH:
+ case STATEMENT_LABEL:
+ case STATEMENT_CASE_LABEL:
+ last = next;
+ next = next->base.next;
+ break;
+
+ case STATEMENT_WHILE: {
+continue_while:
+ if (next->base.reachable)
+ return;
+ next->base.reachable = true;
+
+ while_statement_t const *const whiles = &next->whiles;
+ int const val = determine_truth(whiles->condition);
+
+ if (val >= 0)
+ check_reachable(whiles->body);
+
+ if (val > 0)
+ return;
+
+ last = next;
+ next = next->base.next;
+ break;
+ }
+
+ case STATEMENT_DO_WHILE: {
+continue_do_while:
+ if (next->base.reachable)
+ return;
+ next->base.reachable = true;
+
+ do_while_statement_t const *const dw = &next->do_while;
+ int const val = determine_truth(dw->condition);
+
+ if (val >= 0)
+ check_reachable(dw->body);
+
+ if (val > 0)
+ return;
+
+ last = next;
+ next = next->base.next;
+ break;
+ }
+
+ case STATEMENT_FOR: {
+continue_for:;
+ for_statement_t *const fors = &next->fors;
+
+ fors->step_reachable = true;
+
+ if (fors->condition_reachable)
+ return;
+ fors->condition_reachable = true;
+
+ expression_t const *const cond = fors->condition;
+ int const val =
+ cond == NULL ? 1 : determine_truth(cond);
+
+ if (val >= 0)
+ check_reachable(fors->body);
+
+ if (val > 0)
+ return;
+
+ last = next;
+ next = next->base.next;
+ break;
+ }
+
+ case STATEMENT_MS_TRY:
+ panic("unimplemented");
+ }
+ }
+
+ if (next == NULL) {
+ next = stmt->base.parent;
+ if (next == NULL) {
+ warningf(&stmt->base.source_position,
+ "control reaches end of non-void function");
+ }
+ }
+
+ check_reachable(next);
+}
+
+static void check_unreachable(statement_t const* const stmt)
+{
+ if (!stmt->base.reachable &&
+ stmt->kind != STATEMENT_COMPOUND &&
+ stmt->kind != STATEMENT_DO_WHILE &&
+ stmt->kind != STATEMENT_FOR) {
+ warningf(&stmt->base.source_position,
+ "statement is unreachable");
+ }
+
+ switch (stmt->kind) {
+ case STATEMENT_INVALID:
+ case STATEMENT_EMPTY:
+ case STATEMENT_RETURN:
+ case STATEMENT_DECLARATION:
+ case STATEMENT_EXPRESSION:
+ case STATEMENT_CONTINUE:
+ case STATEMENT_BREAK:
+ case STATEMENT_GOTO:
+ case STATEMENT_ASM:
+ case STATEMENT_LEAVE:
+ break;
+
+ case STATEMENT_COMPOUND:
+ if (stmt->compound.statements)
+ check_unreachable(stmt->compound.statements);
+ break;
+
+ case STATEMENT_IF:
+ check_unreachable(stmt->ifs.true_statement);
+ if (stmt->ifs.false_statement != NULL)
+ check_unreachable(stmt->ifs.false_statement);
+ break;
+
+ case STATEMENT_SWITCH:
+ check_unreachable(stmt->switchs.body);
+ break;
+
+ case STATEMENT_LABEL:
+ check_unreachable(stmt->label.statement);
+ break;
+
+ case STATEMENT_CASE_LABEL:
+ check_unreachable(stmt->case_label.statement);
+ break;
+
+ case STATEMENT_WHILE:
+ check_unreachable(stmt->whiles.body);
+ break;
+
+ case STATEMENT_DO_WHILE:
+ check_unreachable(stmt->do_while.body);
+ if (!stmt->base.reachable) {
+ expression_t const *const cond = stmt->do_while.condition;
+ if (determine_truth(cond) >= 0) {
+ warningf(&cond->base.source_position,
+ "condition of do-while-loop is unreachable");
+ }
+ }
+ break;
+
+ case STATEMENT_FOR: {
+ for_statement_t const* const fors = &stmt->fors;
+
+ if (!stmt->base.reachable && fors->initialisation != NULL) {
+ warningf(&fors->initialisation->base.source_position,
+ "initialisation of for-statement is unreachable");
+ }
+
+ if (!fors->condition_reachable && fors->condition != NULL) {
+ warningf(&fors->condition->base.source_position,
+ "condition of for-statement is unreachable");
+ }
+
+ if (!fors->step_reachable && fors->step != NULL) {
+ warningf(&fors->step->base.source_position,
+ "step of for-statement is unreachable");
+ }
+
+ check_unreachable(stmt->fors.body);
+ break;
+ }
+
+ case STATEMENT_MS_TRY:
+ panic("unimplemented");
+ }
+
+ if (stmt->base.next)
+ check_unreachable(stmt->base.next);
+}
+
static void parse_external_declaration(void)
{
/* function-definitions and declarations both start with declaration
int label_stack_top = label_top();
declaration_t *old_current_function = current_function;
current_function = declaration;
+ current_parent = NULL;
- declaration->init.statement = parse_compound_statement(false);
+ statement_t *const body = parse_compound_statement(false);
+ declaration->init.statement = body;
first_err = true;
check_labels();
check_declarations();
+ if (warning.return_type || warning.unreachable_code) {
+ check_reachable(body);
+ if (warning.unreachable_code)
+ check_unreachable(body);
+ }
+ assert(current_parent == NULL);
assert(current_function == declaration);
current_function = old_current_function;
label_pop_to(label_stack_top);
*pos = token.source_position;
statement->case_label.expression = parse_expression();
+ PUSH_PARENT(statement);
+
if (c_mode & _GNUC) {
if (token.type == T_DOTDOTDOT) {
next_token();
errorf(&inner_stmt->base.source_position, "declaration after case label");
}
+ POP_PARENT;
return statement;
end_error:
+ POP_PARENT;
return create_invalid_statement();
}
eat(T_default);
statement_t *statement = allocate_statement_zero(STATEMENT_CASE_LABEL);
-
statement->base.source_position = token.source_position;
+ PUSH_PARENT(statement);
+
expect(':');
if (current_switch != NULL) {
const case_label_statement_t *def_label = find_default_label(current_switch);
errorf(&inner_stmt->base.source_position, "declaration after default label");
}
+ POP_PARENT;
return statement;
end_error:
+ POP_PARENT;
return create_invalid_statement();
}
declaration_t *label = get_label(symbol);
+ statement_t *const statement = allocate_statement_zero(STATEMENT_LABEL);
+ statement->base.source_position = token.source_position;
+ statement->label.label = label;
+
+ PUSH_PARENT(statement);
+
/* if source position is already set then the label is defined twice,
* otherwise it was just mentioned in a goto so far */
if (label->source_position.input_name != NULL) {
symbol, &label->source_position);
} else {
label->source_position = token.source_position;
+ label->init.statement = statement;
}
- statement_t *statement = allocate_statement_zero(STATEMENT_LABEL);
-
- statement->base.source_position = token.source_position;
- statement->label.label = label;
-
eat(':');
if (token.type == '}') {
}
label_last = &statement->label;
+ POP_PARENT;
return statement;
}
statement_t *statement = allocate_statement_zero(STATEMENT_IF);
statement->base.source_position = token.source_position;
+ PUSH_PARENT(statement);
+
expect('(');
add_anchor_token(')');
statement->ifs.condition = parse_expression();
statement->ifs.false_statement = parse_statement();
}
+ POP_PARENT;
return statement;
end_error:
+ POP_PARENT;
return create_invalid_statement();
}
statement_t *statement = allocate_statement_zero(STATEMENT_SWITCH);
statement->base.source_position = token.source_position;
+ PUSH_PARENT(statement);
+
expect('(');
expression_t *const expr = parse_expression();
type_t * type = skip_typeref(expr->base.type);
warningf(&statement->base.source_position, "switch has no default case");
}
+ POP_PARENT;
return statement;
end_error:
+ POP_PARENT;
return create_invalid_statement();
}
statement_t *statement = allocate_statement_zero(STATEMENT_WHILE);
statement->base.source_position = token.source_position;
+ PUSH_PARENT(statement);
+
expect('(');
add_anchor_token(')');
statement->whiles.condition = parse_expression();
statement->whiles.body = parse_loop_body(statement);
+ POP_PARENT;
return statement;
end_error:
+ POP_PARENT;
return create_invalid_statement();
}
eat(T_do);
statement_t *statement = allocate_statement_zero(STATEMENT_DO_WHILE);
-
statement->base.source_position = token.source_position;
+ PUSH_PARENT(statement)
+
add_anchor_token(T_while);
statement->do_while.body = parse_loop_body(statement);
rem_anchor_token(T_while);
expect(')');
expect(';');
+ POP_PARENT;
return statement;
end_error:
+ POP_PARENT;
return create_invalid_statement();
}
statement_t *statement = allocate_statement_zero(STATEMENT_FOR);
statement->base.source_position = token.source_position;
+ PUSH_PARENT(statement);
+
int top = environment_top();
scope_t *last_scope = scope;
set_scope(&statement->fors.scope);
set_scope(last_scope);
environment_pop_to(top);
+ POP_PARENT;
return statement;
end_error:
+ POP_PARENT;
rem_anchor_token(')');
assert(scope == &statement->fors.scope);
set_scope(last_scope);
static statement_t *parse_compound_statement(bool inside_expression_statement)
{
statement_t *statement = allocate_statement_zero(STATEMENT_COMPOUND);
-
statement->base.source_position = token.source_position;
+ PUSH_PARENT(statement);
+
eat('{');
add_anchor_token('}');
set_scope(last_scope);
environment_pop_to(top);
+ POP_PARENT;
return statement;
}
projects / cparser / commitdiff