V4: clarify current vs. next instruction offset in ByteCodeHandler

When executing an interpreter instruction, the code pointer points to
the next instruction. However, sometimes a pointer to the current
instruction is needed. That was hacked-around by having startInstruction
be called before updating the pointer. This is confusing and leads to
unexpected off-by-one-instruction cases.

So now during startInstruction calls and generate_instructionName calls,
there is a currentInstructionOffset() and a nextInstructionOffset() that
do what's on the tin in both places.

Change-Id: Ie8dd35ff0a7d236f008030ef4c29ec3f31c07349
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/qml/jit/qv4baselinejit_p.h b/src/qml/jit/qv4baselinejit_p.h
index 71b9dda9b9..6f066bb9a5 100644
--- a/src/qml/jit/qv4baselinejit_p.h
+++ b/src/qml/jit/qv4baselinejit_p.h
@@ -214,7 +214,10 @@ public:
 
 protected:
     bool hasLabel() const
-    { return std::find(labels.cbegin(), labels.cend(), instructionOffset()) != labels.cend(); }
+    { return std::find(labels.cbegin(), labels.cend(), currentInstructionOffset()) != labels.cend(); }
+
+    int absoluteOffsetForJump(int relativeOffset) const
+    { return nextInstructionOffset() + relativeOffset; }
 
 private:
     QV4::Function *function;