820159 - BaselineCompiler: Increment script useCount on entry and loopentry.

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Kannan Vijayan [:djvj]]

This is in preparation for enabling ion compilation of scripts that are executing in baseline.  First we need to be able to tell when to kick off ion compile, which means keeping track of useCounts within baseline-compiled scripts.

Comment 1

[Kannan Vijayan [:djvj]]

Attachment: Increment usecount on script and loop entry.

This adds code to increment a script's useCount on script entry and LOOPENTRY ops.  The increment of useCount itself is done inline.  If the usecount exceeds the usesBeforeCompile for ion, then the UseCount IC is entered, which contains a single UseCount_Fallback entry which can later be altered to implement bailout.

Comment 2

[Kannan Vijayan [:djvj]]

Comment on attachment 690991 [details] [diff] [review]
Increment usecount on script and loop entry.

Review of attachment 690991 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/ion/BaselineCompiler.cpp
@@ +484,5 @@
>  
>  bool
>  BaselineCompiler::emit_JSOP_LOOPENTRY()
>  {
> +    return emitUseCountIncrement();

NOTE: emit_JSOP_LOOPHEAD needs a popRegsAndSync(0) before calling emitUseCountIncrement().  That change has been made locally on my patch already.

Comment 3

[Kannan Vijayan [:djvj]]

https://hg.mozilla.org/projects/ionmonkey/rev/ce645189e528