[wasm] Stack inspection support for asm.js frames

[wasm] Stack inspection support for asm.js frames

This CL fixes the debugger interface to provide correct (high-level)
information for asm.js frames.
It moves the computation of the source position from the FrameInspector
to the individual StackFrame implementations, such that we can easily
specualize it for certain frame types, and can potentially reuse this
in other locations.

Also, we are finalizing the setup of the wasm module earlier, before
executing the start function. This is required for correct stack traces
during the execution of the start function.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:4203
Committed: https://crrev.com/e902b69d881059cce739a88d3e5f9ce95b5e0625
Cr-Commit-Position: refs/heads/master@{#40268}

[Clemens Hammacher, 2016-10-12 14:48:30]

The CQ bit was checked by clemensh@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-10-12 14:48:32]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Clemens Hammacher, 2016-10-12 14:50:21]

Description was changed from

==========
[wasm] Stack inspection support for asm.js frames

This CL fixes the debugger interface to provide correct (high-level)
information for asm.js frames.
It moves the computation of the source position from the FrameInspector
to the individual StackFrame implementations, such that we can use
dynamic dispatch and can potentially reuse this in other locations.

Also, we are finalizing the setup of the wasm module earlier, before
executing the start function. This is required for correct stack traces
during the execution of the start function.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:4203
==========

to

==========
[wasm] Stack inspection support for asm.js frames

This CL fixes the debugger interface to provide correct (high-level)
information for asm.js frames.
It moves the computation of the source position from the FrameInspector
to the individual StackFrame implementations, such that we can easily
specualize it for certain frame types, and can potentially reuse this
in other locations.

Also, we are finalizing the setup of the wasm module earlier, before
executing the start function. This is required for correct stack traces
during the execution of the start function.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:4203
==========

[Clemens Hammacher, 2016-10-12 14:56:56]

I first wanted to implement this by adding a new frame type ASM_JS_WASM with an
AsmJsWasmFrame inheriting from WasmFrame. That would have been nicer IMHO, but
the frame type needs to be determined during the stack walk already, and at that
time it is generally not allowed to access heap objects. Pointers might be
broken if the stack walk is triggered during GC. It would thus require to add a
new flag to the Code object itself (is_asm_js_wasm), which can be read at that
stage. That works, but adds lots of code at different locations, which I
considered not worthwhile for now.

The implementation in this CL achieves the same by explicitly checking for
asm.js frames in two methods of WasmFrame.

[commit-bot: I haz the power, 2016-10-12 15:18:25]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-10-12 15:18:26]

Dry run: This issue passed the CQ dry run.

[titzer, 2016-10-12 15:25:01]

On 2016/10/12 14:56:56, Clemens Hammacher wrote:
> I first wanted to implement this by adding a new frame type ASM_JS_WASM with
an
> AsmJsWasmFrame inheriting from WasmFrame. That would have been nicer IMHO, but
> the frame type needs to be determined during the stack walk already, and at
that
> time it is generally not allowed to access heap objects. Pointers might be
> broken if the stack walk is triggered during GC. It would thus require to add
a
> new flag to the Code object itself (is_asm_js_wasm), which can be read at that
> stage. That works, but adds lots of code at different locations, which I
> considered not worthwhile for now.
> 
> The implementation in this CL achieves the same by explicitly checking for
> asm.js frames in two methods of WasmFrame.

lgtm, but will defer to Yang's comments.

[Yang, 2016-10-13 12:01:02]

On 2016/10/12 15:25:01, titzer wrote:
> On 2016/10/12 14:56:56, Clemens Hammacher wrote:
> > I first wanted to implement this by adding a new frame type ASM_JS_WASM with
> an
> > AsmJsWasmFrame inheriting from WasmFrame. That would have been nicer IMHO,
but
> > the frame type needs to be determined during the stack walk already, and at
> that
> > time it is generally not allowed to access heap objects. Pointers might be
> > broken if the stack walk is triggered during GC. It would thus require to
add
> a
> > new flag to the Code object itself (is_asm_js_wasm), which can be read at
that
> > stage. That works, but adds lots of code at different locations, which I
> > considered not worthwhile for now.
> > 
> > The implementation in this CL achieves the same by explicitly checking for
> > asm.js frames in two methods of WasmFrame.
> 
> lgtm, but will defer to Yang's comments.

Nice. lgtm.

[Clemens Hammacher, 2016-10-13 13:31:49]

The CQ bit was checked by clemensh@chromium.org

[commit-bot: I haz the power, 2016-10-13 13:32:07]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-13 13:54:52]

Description was changed from

==========
[wasm] Stack inspection support for asm.js frames

This CL fixes the debugger interface to provide correct (high-level)
information for asm.js frames.
It moves the computation of the source position from the FrameInspector
to the individual StackFrame implementations, such that we can easily
specualize it for certain frame types, and can potentially reuse this
in other locations.

Also, we are finalizing the setup of the wasm module earlier, before
executing the start function. This is required for correct stack traces
during the execution of the start function.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:4203
==========

to

==========
[wasm] Stack inspection support for asm.js frames

This CL fixes the debugger interface to provide correct (high-level)
information for asm.js frames.
It moves the computation of the source position from the FrameInspector
to the individual StackFrame implementations, such that we can easily
specualize it for certain frame types, and can potentially reuse this
in other locations.

Also, we are finalizing the setup of the wasm module earlier, before
executing the start function. This is required for correct stack traces
during the execution of the start function.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:4203
==========

[commit-bot: I haz the power, 2016-10-13 13:54:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-13 13:55:15]

Description was changed from

==========
[wasm] Stack inspection support for asm.js frames

This CL fixes the debugger interface to provide correct (high-level)
information for asm.js frames.
It moves the computation of the source position from the FrameInspector
to the individual StackFrame implementations, such that we can easily
specualize it for certain frame types, and can potentially reuse this
in other locations.

Also, we are finalizing the setup of the wasm module earlier, before
executing the start function. This is required for correct stack traces
during the execution of the start function.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:4203
==========

to

==========
[wasm] Stack inspection support for asm.js frames

This CL fixes the debugger interface to provide correct (high-level)
information for asm.js frames.
It moves the computation of the source position from the FrameInspector
to the individual StackFrame implementations, such that we can easily
specualize it for certain frame types, and can potentially reuse this
in other locations.

Also, we are finalizing the setup of the wasm module earlier, before
executing the start function. This is required for correct stack traces
during the execution of the start function.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:4203

Committed: https://crrev.com/e902b69d881059cce739a88d3e5f9ce95b5e0625
Cr-Commit-Position: refs/heads/master@{#40268}
==========

[commit-bot: I haz the power, 2016-10-13 13:55:16]

Patchset 1 (id:??) landed as
https://crrev.com/e902b69d881059cce739a88d3e5f9ce95b5e0625
Cr-Commit-Position: refs/heads/master@{#40268}