7020118: Alter frame assignability to allow for exception handler coverage of invokespecial <init>
Summary: Add special rule to allow assignment of frames with uninit flags set.
Reviewed-by: never, coleenp
--- a/hotspot/src/share/vm/classfile/stackMapFrame.cpp Mon Feb 28 14:19:52 2011 +0100
+++ b/hotspot/src/share/vm/classfile/stackMapFrame.cpp Mon Feb 28 16:01:59 2011 -0500
@@ -170,6 +170,44 @@
return true;
}
+bool StackMapFrame::has_flag_match_exception(
+ const StackMapFrame* target) const {
+ // We allow flags of {UninitThis} to assign to {} if-and-only-if the
+ // target frame does not depend upon the current type.
+ // This is slightly too strict, as we need only enforce that the
+ // slots that were initialized by the <init> (the things that were
+ // UninitializedThis before initialize_object() converted them) are unused.
+ // However we didn't save that information so we'll enforce this upon
+ // anything that might have been initialized. This is a rare situation
+ // and javac never generates code that would end up here, but some profilers
+ // (such as NetBeans) might, when adding exception handlers in <init>
+ // methods to cover the invokespecial instruction. See 7020118.
+
+ assert(max_locals() == target->max_locals() &&
+ stack_size() == target->stack_size(), "StackMap sizes must match");
+
+ VerificationType top = VerificationType::top_type();
+ VerificationType this_type = verifier()->current_type();
+
+ if (!flag_this_uninit() || target->flags() != 0) {
+ return false;
+ }
+
+ for (int i = 0; i < target->locals_size(); ++i) {
+ if (locals()[i] == this_type && target->locals()[i] != top) {
+ return false;
+ }
+ }
+
+ for (int i = 0; i < target->stack_size(); ++i) {
+ if (stack()[i] == this_type && target->stack()[i] != top) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
bool StackMapFrame::is_assignable_to(const StackMapFrame* target, TRAPS) const {
if (_max_locals != target->max_locals() || _stack_size != target->stack_size()) {
return false;
@@ -182,7 +220,9 @@
bool match_stack = is_assignable_to(
_stack, target->stack(), _stack_size, CHECK_false);
bool match_flags = (_flags | target->flags()) == target->flags();
- return (match_locals && match_stack && match_flags);
+
+ return match_locals && match_stack &&
+ (match_flags || has_flag_match_exception(target));
}
VerificationType StackMapFrame::pop_stack_ex(VerificationType type, TRAPS) {
--- a/hotspot/src/share/vm/classfile/stackMapFrame.hpp Mon Feb 28 14:19:52 2011 +0100
+++ b/hotspot/src/share/vm/classfile/stackMapFrame.hpp Mon Feb 28 16:01:59 2011 -0500
@@ -228,6 +228,8 @@
bool is_assignable_to(
VerificationType* src, VerificationType* target, int32_t len, TRAPS) const;
+ bool has_flag_match_exception(const StackMapFrame* target) const;
+
// Debugging
void print() const PRODUCT_RETURN;
};
--- a/hotspot/src/share/vm/classfile/verificationType.hpp Mon Feb 28 14:19:52 2011 +0100
+++ b/hotspot/src/share/vm/classfile/verificationType.hpp Mon Feb 28 16:01:59 2011 -0500
@@ -128,6 +128,7 @@
// Create verification types
static VerificationType bogus_type() { return VerificationType(Bogus); }
+ static VerificationType top_type() { return bogus_type(); } // alias
static VerificationType null_type() { return VerificationType(Null); }
static VerificationType integer_type() { return VerificationType(Integer); }
static VerificationType float_type() { return VerificationType(Float); }