[wasm] TrapIf and TrapUnless TurboFan operators implemented on arm64.

[wasm] TrapIf and TrapUnless TurboFan operators implemented on arm64.

Please take a special look at the code I generate to call the runtime
function for the traps. The correct handling of csp vs jssp seems to be
quite tricky.

Original commit message:
[wasm] Introduce the TrapIf and TrapUnless operators to generate trap code.

Some instructions in WebAssembly trap for some inputs, which means that the
execution is terminated and (at least at the moment) a JavaScript exception is
thrown. Examples for traps are out-of-bounds memory accesses, or integer
divisions by zero.

Without the TrapIf and TrapUnless operators trap check in WebAssembly introduces 5
TurboFan nodes (branch, if_true, if_false, trap-reason constant, trap-position
constant), in addition to the trap condition itself. Additionally, each
WebAssembly function has four TurboFan nodes (merge, effect_phi, 2 phis) whose
number of inputs is linear to the number of trap checks in the function.
Especially for functions with high numbers of trap checks we observe a
significant slowdown in compilation time, down to 0.22 MiB/s in the sqlite
benchmark instead of the average of 3 MiB/s in other benchmarks. By introducing
a TrapIf common operator only a single node is necessary per trap check, in
addition to the trap condition. Also the nodes which are shared between trap
checks (merge, effect_phi, 2 phis) would disappear. First measurements suggest a
speedup of 30-50% on average.

This CL only implements TrapIf and TrapUnless on x64. The implementation is also
hidden behind the --wasm-trap-if flag.

Please take a special look at how the source position is transfered from the
instruction selector to the code generator, and at the context that is used for
the runtime call.

R=titzer@chromium.org, georgia.kouveli@arm.com, v8-arm-ports@googlegroups.com

Review-Url: https://codereview.chromium.org/2619203005
Cr-Commit-Position: refs/heads/master@{#42181}
Committed: https://chromium.googlesource.com/v8/v8/+/8bdcc77f22d80f74ee8aaeee10c7e7fef868ab85

[ahaas, 2017-01-10 13:34:46]

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

[commit-bot: I haz the power, 2017-01-10 13:34:55]

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

[titzer, 2017-01-10 13:58:09]

On 2017/01/10 13:34:45, ahaas wrote:

lgtm, even the tricky bits :-)

[commit-bot: I haz the power, 2017-01-10 14:03:05]

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

[commit-bot: I haz the power, 2017-01-10 14:03:06]

Dry run: This issue passed the CQ dry run.

[georgia.kouveli, 2017-01-10 14:37:52]

One minor comment, otherwise looks good to me too.

https://codereview.chromium.org/2619203005/diff/1/src/compiler/arm64/instruct...
File src/compiler/arm64/instruction-selector-arm64.cc (right):

https://codereview.chromium.org/2619203005/diff/1/src/compiler/arm64/instruct...
src/compiler/arm64/instruction-selector-arm64.cc:2191: // Only handle branches
and deoptimisations and traps.
The code here has not been updated to handle traps, so the comment update is
misleading.

[ahaas, 2017-01-10 14:44:50]

https://codereview.chromium.org/2619203005/diff/1/src/compiler/arm64/instruct...
File src/compiler/arm64/instruction-selector-arm64.cc (right):

https://codereview.chromium.org/2619203005/diff/1/src/compiler/arm64/instruct...
src/compiler/arm64/instruction-selector-arm64.cc:2191: // Only handle branches
and deoptimisations and traps.
On 2017/01/10 at 14:37:52, georgia.kouveli wrote:
> The code here has not been updated to handle traps, so the comment update is
misleading.

I changed the comment back.

[ahaas, 2017-01-10 14:45:07]

The CQ bit was checked by ahaas@chromium.org

[ahaas, 2017-01-10 14:45:07]

The patchset sent to the CQ was uploaded after l-g-t-m from titzer@chromium.org
Link to the patchset: https://codereview.chromium.org/2619203005/#ps20001
(title: "Update a comment")

[commit-bot: I haz the power, 2017-01-10 14:45:11]

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, 2017-01-10 15:12:57]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1484059507071390,
"parent_rev": "a3ea32f656d70b19ed2a308ba142a1684c721d78", "commit_rev":
"8bdcc77f22d80f74ee8aaeee10c7e7fef868ab85"}

[commit-bot: I haz the power, 2017-01-10 15:13:00]

Description was changed from

==========
[wasm] TrapIf and TrapUnless TurboFan operators implemented on arm64.

Please take a special look at the code I generate to call the runtime
function for the traps. The correct handling of csp vs jssp seems to be
quite tricky.

Original commit message:
[wasm] Introduce the TrapIf and TrapUnless operators to generate trap code.

Some instructions in WebAssembly trap for some inputs, which means that the
execution is terminated and (at least at the moment) a JavaScript exception is
thrown. Examples for traps are out-of-bounds memory accesses, or integer
divisions by zero.

Without the TrapIf and TrapUnless operators trap check in WebAssembly introduces
5
TurboFan nodes (branch, if_true, if_false, trap-reason constant, trap-position
constant), in addition to the trap condition itself. Additionally, each
WebAssembly function has four TurboFan nodes (merge, effect_phi, 2 phis) whose
number of inputs is linear to the number of trap checks in the function.
Especially for functions with high numbers of trap checks we observe a
significant slowdown in compilation time, down to 0.22 MiB/s in the sqlite
benchmark instead of the average of 3 MiB/s in other benchmarks. By introducing
a TrapIf common operator only a single node is necessary per trap check, in
addition to the trap condition. Also the nodes which are shared between trap
checks (merge, effect_phi, 2 phis) would disappear. First measurements suggest a
speedup of 30-50% on average.

This CL only implements TrapIf and TrapUnless on x64. The implementation is also
hidden behind the --wasm-trap-if flag.

Please take a special look at how the source position is transfered from the
instruction selector to the code generator, and at the context that is used for
the runtime call.

R=titzer@chromium.org, georgia.kouveli@arm.com, v8-arm-ports@googlegroups.com
==========

to

==========
[wasm] TrapIf and TrapUnless TurboFan operators implemented on arm64.

Please take a special look at the code I generate to call the runtime
function for the traps. The correct handling of csp vs jssp seems to be
quite tricky.

Original commit message:
[wasm] Introduce the TrapIf and TrapUnless operators to generate trap code.

Some instructions in WebAssembly trap for some inputs, which means that the
execution is terminated and (at least at the moment) a JavaScript exception is
thrown. Examples for traps are out-of-bounds memory accesses, or integer
divisions by zero.

Without the TrapIf and TrapUnless operators trap check in WebAssembly introduces
5
TurboFan nodes (branch, if_true, if_false, trap-reason constant, trap-position
constant), in addition to the trap condition itself. Additionally, each
WebAssembly function has four TurboFan nodes (merge, effect_phi, 2 phis) whose
number of inputs is linear to the number of trap checks in the function.
Especially for functions with high numbers of trap checks we observe a
significant slowdown in compilation time, down to 0.22 MiB/s in the sqlite
benchmark instead of the average of 3 MiB/s in other benchmarks. By introducing
a TrapIf common operator only a single node is necessary per trap check, in
addition to the trap condition. Also the nodes which are shared between trap
checks (merge, effect_phi, 2 phis) would disappear. First measurements suggest a
speedup of 30-50% on average.

This CL only implements TrapIf and TrapUnless on x64. The implementation is also
hidden behind the --wasm-trap-if flag.

Please take a special look at how the source position is transfered from the
instruction selector to the code generator, and at the context that is used for
the runtime call.

R=titzer@chromium.org, georgia.kouveli@arm.com, v8-arm-ports@googlegroups.com

Review-Url: https://codereview.chromium.org/2619203005
Cr-Commit-Position: refs/heads/master@{#42181}
Committed:
https://chromium.googlesource.com/v8/v8/+/8bdcc77f22d80f74ee8aaeee10c7e7fef86...
==========

[commit-bot: I haz the power, 2017-01-10 15:13:00]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/v8/v8/+/8bdcc77f22d80f74ee8aaeee10c7e7fef86...