Remove fromValues <was> Re: IntVector.fromValues is not optimized away ?
forax at univ-mlv.fr
forax at univ-mlv.fr
Wed May 13 19:14:55 UTC 2020
----- Mail original -----
> De: "Paul Sandoz" <paul.sandoz at oracle.com>
> À: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "panama-dev at openjdk.java.net'" <panama-dev at openjdk.java.net>
> Envoyé: Mercredi 13 Mai 2020 19:33:13
> Objet: Remove fromValues <was> Re: IntVector.fromValues is not optimized away ?
> Hi Remi,
>
> Your experience here has motived us to remove fromValues (I’ll send out a
> patch). At this point I think it is more of a distraction, and we can add it
> back later if we can optimize better.
I agree, given that fromValues() is not better than fromArray
>
> Instead the developer would need to do fromArray(species, new int[] { … }) or
> use explicit insertion (which is kind of like a wither method)
At some point, all vectors will be inline types so the VM will see zero.withLane(...).withLane(...) has vdefault.withfield.withfield so the JIT should be able avoid the initialization and generates a better code.
>
> Paul.
Rémi
>
>> On May 9, 2020, at 11:52 AM, Remi Forax <forax at univ-mlv.fr> wrote:
>>
>> Hi all,
>> this may be obvious but do we agree that IntVector.fromValues is not optimized
>> thus really create an array destroying any hope of perf ?
>>
>> I'm trying to see the difference between
>>
>> public int hashCode() {
>> return i1 ^ i2 ^ i3 ^ i4;
>> }
>>
>> and
>>
>> public int hashCode() {
>> var v1 = IntVector.fromValues(IntVector.SPECIES_64, i1, i3);
>> var v2 = IntVector.fromValues(IntVector.SPECIES_64, i2, i4);
>> var result = v1.lanewise(VectorOperators.XOR, v2);
>> return result.lane(0) ^ result.lane(1);
>> }
>>
>> but taking a look to the generated assembly (below), the allocation of the two
>> arrays are still there,
>> too bad because the last 6 instructions are more or less what i was expecting.
>>
>>
>> 0x00007fbb383324dc: mov 0x14(%rsi),%r11d ;*getfield i3
>> {reexecute=0 rethrow=0 return_oop=0}
>> ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 16 (line 14)
>> 0x00007fbb383324e0: mov 0xc(%rsi),%ebp
>> 0x00007fbb383324e3: mov 0x120(%r15),%r8
>> 0x00007fbb383324ea: mov %r8,%r10
>> 0x00007fbb383324ed: add $0x18,%r10
>> 0x00007fbb383324f1: cmp 0x130(%r15),%r10
>> 0x00007fbb383324f8: jae 0x00007fbb383325db
>> 0x00007fbb383324fe: mov %r10,0x120(%r15)
>> 0x00007fbb38332505: prefetchw 0xc0(%r10)
>> 0x00007fbb3833250d: movq $0x1,(%r8)
>> 0x00007fbb38332514: prefetchw 0x100(%r10)
>> 0x00007fbb3833251c: movl $0x70cb1,0x8(%r8) ; {metadata({type
>> array int})}
>> 0x00007fbb38332524: prefetchw 0x140(%r10)
>> 0x00007fbb3833252c: movl $0x2,0xc(%r8)
>> 0x00007fbb38332534: prefetchw 0x180(%r10)
>> 0x00007fbb3833253c: mov %ebp,0x10(%r8)
>> 0x00007fbb38332540: mov %r11d,0x14(%r8) ;*newarray
>> {reexecute=0 rethrow=0 return_oop=0}
>> ; - java.util.Arrays::copyOf at 1 (line 3584)
>> ; - jdk.incubator.vector.IntVector::fromValues at 19 (line 553)
>> ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 20 (line 14)
>> 0x00007fbb38332544: mov 0x18(%rsi),%r9d
>> 0x00007fbb38332548: mov 0x120(%r15),%rax ;*invokestatic extract
>> {reexecute=0 rethrow=0 return_oop=0}
>> ; - jdk.incubator.vector.Int64Vector::laneHelper at 16 (line 482)
>> ; - jdk.incubator.vector.Int64Vector::lane at 36 (line 476)
>> ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 64 (line 17)
>> 0x00007fbb3833254f: mov 0x10(%rsi),%ebp ;*getfield i2
>> {reexecute=0 rethrow=0 return_oop=0}
>> ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 33 (line 15)
>> 0x00007fbb38332552: mov %rax,%r10
>> 0x00007fbb38332555: add $0x18,%r10
>> 0x00007fbb38332559: nopl 0x0(%rax)
>> 0x00007fbb38332560: cmp 0x130(%r15),%r10
>> 0x00007fbb38332567: jae 0x00007fbb3833260d
>> 0x00007fbb3833256d: mov %r10,0x120(%r15)
>> 0x00007fbb38332574: prefetchw 0xc0(%r10)
>> 0x00007fbb3833257c: movq $0x1,(%rax)
>> 0x00007fbb38332583: prefetchw 0x100(%r10)
>> 0x00007fbb3833258b: movl $0x70cb1,0x8(%rax) ; {metadata({type
>> array int})}
>> 0x00007fbb38332592: prefetchw 0x140(%r10)
>> 0x00007fbb3833259a: movl $0x2,0xc(%rax)
>> 0x00007fbb383325a1: prefetchw 0x180(%r10)
>> 0x00007fbb383325a9: mov %ebp,0x10(%rax)
>> 0x00007fbb383325ac: mov %r9d,0x14(%rax) ;*newarray
>> {reexecute=0 rethrow=0 return_oop=0}
>> ; - java.util.Arrays::copyOf at 1 (line 3584)
>> ; - jdk.incubator.vector.IntVector::fromValues at 19 (line 553)
>> ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 44 (line 15)
>> 0x00007fbb383325b0: vmovq 0x10(%rax),%xmm0 ;*invokestatic extract
>> {reexecute=0 rethrow=0 return_oop=0}
>> ; - jdk.incubator.vector.Int64Vector::laneHelper at 16 (line 482)
>> ; - jdk.incubator.vector.Int64Vector::lane at 36 (line 476)
>> ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 64 (line 17)
>> 0x00007fbb383325b5: vpxor 0x10(%r8),%xmm0,%xmm0 ;*invokespecial <init>
>> {reexecute=0 rethrow=0 return_oop=0}
>> ; - jdk.internal.vm.vector.VectorSupport$Vector::<init>@2 (line 104)
>> ; - jdk.incubator.vector.Vector::<init>@2 (line 1122)
>> ; - jdk.incubator.vector.AbstractVector::<init>@2 (line 67)
>> ; - jdk.incubator.vector.IntVector::<init>@2 (line 55)
>> ; - jdk.incubator.vector.Int64Vector::<init>@2 (line 58)
>> ; - jdk.incubator.vector.Int64Vector::vectorFactory at 5 (line 169)
>> ; - jdk.incubator.vector.Int64Vector::vectorFactory at 2 (line 41)
>> ; - jdk.incubator.vector.IntVector$IntSpecies::vectorFactory at 5 (line 3718)
>> ; - jdk.incubator.vector.IntVector::fromValues at 22 (line 553)
>> ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 44 (line 15)
>> 0x00007fbb383325bb: vpextrd $0x1,%xmm0,%r11d
>> 0x00007fbb383325c1: vmovd %xmm0,%eax
>> 0x00007fbb383325c5: xor %r11d,%eax
>> 0x00007fbb383325c8: vzeroupper
>>
>> regards,
> > Rémi
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