hg: mlvm/mlvm/jdk: cval: hang caches on classes

[Rémi Forax]

Not sure to understand the full patch,
anyway nextHashCode should be declared final.

regards,

Rémi

On 08/04/2011 10:21 AM, John Rose wrote:
> Benchmarks indicate a 4x speedup from previous implementation.
> The fast path has 7 memory references.  Here's what it looks like:
>
>       {mov eax, (cval : ClassValue); mov edx, (type : Class)}
>   M1: movecx, [edx+0x60]  ;*getfield Class.classValueCache : Entry[]
>   M2: movebp, [ecx+0x8]   ;*arraylength
>       {mov esi, ebp; dec esi}
>   M3: andesi, [eax+0x8]   ;*iand ClassValue.hashCodeForCache
>       {cmp esi, ebp; jnc (slow)}
>   M4: movecx, [ecx+esi*4+0xC]  ;*aaload : Entry
>       {implicit cmp ecx, 0; jz (slow)}
>   M5: movesi, [ecx+0x8]   ;*getfield WeakReference.referent : 
> ClassValue$Version
>   M6: movebp, [eax+0xC]   ;*getfield ClassValue.version : 
> ClassValue$Version
>       {cmp esi, ebp; jnz (slow)}
>   M7: moveax, [ecx+0x18]  ;*getfield value
>       {mov (result : T), eax}
>
> That's probably good enough for most uses.
>
> All of the memory references are possible CSE and loop invariants.
> I saw a too-simple benchmark loop collapse completely to constant time.
>
> The range check (of the form a[a.length-1 & i]) could be simplified 
> with a little work.
>
> The version check defends against ClassValue.remove.
> Maybe it could be removed by push notification, but it's probably not 
> worth it.
>
> -- John
>
> On Aug 3, 2011, at 9:58 PM, john.r.rose at oracle.com 
> <mailto:john.r.rose at oracle.com> wrote:
>
>> Changeset: c26fceff6309
>> Author:    jrose
>> Date:      2011-08-03 21:57 -0700
>> URL: http://hg.openjdk.java.net/mlvm/mlvm/jdk/rev/c26fceff6309
>>
>> cval: hang caches on classes
>>
>> + cval-tune-7030453.patch
>> ! series
>
>
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