Rework unwind handling

The old code was rather convoluted and expanded to quite
a bit of bytecode. It was also very hard to fix some
of the remaining issues with unwinding in there.

The new code handles unwinding a bit differently. Basically,
we now have three instructions to do what the spec requires.

SetUnwindHandler is the same as the old SetExceptionHandler
instruction. It basically tells the runtime where to jump to
to handle any abrupt completion (ie. throw/break/continue/return)
that requires unwinding.

UnwindToLabel is a new instruction that is used for unwinding
break/continue/return statements. It takes two arguments, one
telling the runtime how many levels to unwind and the second
a target label to jump to when unwinding is done.

UnwindDispatch is the third instruction and is invoked at
the end of each unwind block to dispatch the the parent
unwind handler if required and thus implement the support
for the levelled unwinding.

Change-Id: I079a39d0d897b3ecc2f0dc631ca29b25eae05250
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/qml/jit/qv4assembler_p.h b/src/qml/jit/qv4assembler_p.h
index 73faf7b69f..d41b79f562 100644
--- a/src/qml/jit/qv4assembler_p.h
+++ b/src/qml/jit/qv4assembler_p.h
@@ -140,10 +140,9 @@ public:
     void jump(int offset);
     void jumpTrue(int offset);
     void jumpFalse(int offset);
+    void jumpNoException(int offset);
     void jumpNotUndefined(int offset);
     void jumpEmpty(int offset);
-    void jumpStrictEqualStackSlotInt(int lhs, int rhs, int offset);
-    void jumpStrictNotEqualStackSlotInt(int lhs, int rhs, int offset);
 
     // stuff for runtime calls
     void prepareCallWithArgCount(int argc);
@@ -164,6 +163,8 @@ public:
     void setException();
     void setUnwindHandler(int offset);
     void clearUnwindHandler();
+    void unwindDispatch();
+    void unwindToLabel(int level, int offset);
     void pushCatchContext(int index, int name);
     void popContext();