870052 - IonMonkey: Add some tweaks to reduce recompilation on asm.js apps

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Brian Hackett [Laid off!]]

Attachment: patch

The attached patch greatly improves the compiler's behavior on the box2d asm.js/emscripten benchmark.  In combination with the patches for bug 864220 and bug 864218, running with --no-asmjs --ion-limit-script-size=off --ion-regalloc=backtracking I get frame averages of about 13 (ms?) vs. 10 with asm.  Trunk is about 45.

This is a mix of porting some existing tweaks from analyzeTypes, adding a few new ones and removing some unnecessary code.

Comment 1

[Jan de Mooij [:jandem]]

Comment on attachment 747069 [details] [diff] [review]
patch

Review of attachment 747069 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/ion/IonBuilder.cpp
@@ +4621,5 @@
> +    types::StackTypeSet *observed = script()->analysis()->bytecodeTypes(pc);
> +    if (observed->empty() && observed->noConstraints()) {
> +        if (BytecodeFlowsToBitop(pc)) {
> +            observed->addType(cx, types::Type::Int32Type());
> +        } else if (*(pc + GetBytecodeLength(pc)) == JSOP_POS) {

Nit: (*GetNextPc(pc) == JSOP_POS)

@@ +4624,5 @@
> +            observed->addType(cx, types::Type::Int32Type());
> +        } else if (*(pc + GetBytecodeLength(pc)) == JSOP_POS) {
> +            // Note: this is lame, overspecialized on the code patterns used
> +            // by asm.js and should be replaced by a more general mechanism.
> +            observed->addType(cx, types::Type::DoubleType());

Worth filing a follow-up bug for this.

::: js/src/ion/VMFunctions.cpp
@@ +73,2 @@
>      if (thisv.isMagic(JS_IS_CONSTRUCTING))
> +        return InvokeConstructor(cx, ObjectValue(*fun), argc, argvWithoutThis, rval);

This works because all calls are monitored now right? Good find.

Comment 2

[Brian Hackett [Laid off!]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/63b006573c65

Comment 3

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/63b006573c65