Goal of this CL: explicit return from non-async function has position after
return expression as return position (will unblock [1]).
BytecodeArrayBuilder has SetStatementPosition and SetExpressionPosition methods.
If one of these methods is called then next generated bytecode will get passed
position. It's general treatment for most cases.
Unfortunately it doesn't work for Returns:
- debugger requires source positions exactly on kReturn bytecode in stepping
implementation,
- BytecodeGenerator::BuildReturn and BytecodeGenerator::BuildAsyncReturn
generates more then one bytecode and general solution will put return position
on first generated bytecode,
- it's not easy to split BuildReturn function into two parts to allow something
like following in BytecodeGenerator::VisitReturnStatement since generated
bytecodes are actually controlled by execution_control().
..->BuildReturnPrologue();
..->SetReturnPosition(stmt);
..->Return();
In this CL we pass ReturnStatement through ExecutionControl and use it for
position when we emit return bytecode right here.
So this CL only will improve return position for returns inside of non-async
functions, I'll address async functions later.
[1] https://chromium-review.googlesource.com/c/543161/
Change-Id: Iede512c120b00c209990bf50c20e7d23dc0d65db
Reviewed-on: https://chromium-review.googlesource.com/560738
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46687}
V8 has internal mechanism to ignore steps and breaks inside internal scripts, in this CL it's reused for blackboxing implementation.
Advantages:
- much faster blackboxing implementation (before we at least wrap and collect current call stack for each step),
- get rid of StepFrame action and potential pause in blackboxed code after N StepFrame steps,
- simplification of debugger agent logic.
Disadvtanges:
- currently when user was paused in blackboxed code (e.g. on breakpoint) and then makes step action, debugger ignores blackboxed state of the script and allows to use step actions as usual - this behavior is regressed, we still able to support it on frontend side.
Current state and proposed changes for blackboxing: https://docs.google.com/document/d/1hnzaXPAN8_QC5ENxIgxgMNDbXLraM_OXT73rAyijTF8/edit?usp=sharing
BUG=v8:5842
R=yangguo@chromium.org,dgozman@chromium.org,alph@chromium.org
Review-Url: https://codereview.chromium.org/2633803002
Cr-Commit-Position: refs/heads/master@{#42614}
