IntVector.fromValues is not optimized away ?

[Paul Sandoz]

I meant replacing the N fields with an an int[] field.

Your use-case is exposing some interesting holes in the code gen, But, I presume you are not very serious :-), are you? Given you only have four values to reduce.

Paul.

> On May 11, 2020, at 1:43 PM, forax at univ-mlv.fr wrote:
> 
> 
> 
> 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: Lundi 11 Mai 2020 22:31:01
> Objet: Re: IntVector.fromValues is not optimized away ?
> Grouping the N int fields into an int[] array is likely the most optimal right now.  
> 
> We are a bit stuck until HS is enhanced to better track and match source patterns of element values the vector is composed of. Hence my recommendation.
> 
> I doubt N vector insertion instructions will greatly improve matters on their own, perhaps in combination for fields to avoid the temporary buffer.
> 
> If i try to create an intermediary array of int, it's not elided by HS
> By example for this code:
>       var v1 = IntVector.fromArray(IntVector.SPECIES_64, new int[] { i1, i3 }, 0); 
>       var v2 = IntVector.fromArray(IntVector.SPECIES_64, new int[] { i2, i4 }, 0); 
>       var result = v1.lanewise(VectorOperators.XOR, v2); 
>       return result.lane(0) ^ result.lane(1);
> 
> The first line generates:
>   0x00007f64d0337e5f:   mov    0x120(%r15),%r8 
>   0x00007f64d0337e66:   mov    %r8,%r10 
>   0x00007f64d0337e69:   add    $0x18,%r10 
>   0x00007f64d0337e6d:   cmp    0x130(%r15),%r10 
>   0x00007f64d0337e74:   jae    0x00007f64d0337f62 
>   0x00007f64d0337e7a:   mov    %r10,0x120(%r15) 
>   0x00007f64d0337e81:   prefetchw 0xc0(%r10) 
>   0x00007f64d0337e89:   movq   $0x1,(%r8) 
>   0x00007f64d0337e90:   prefetchw 0x100(%r10) 
>   0x00007f64d0337e98:   movl   $0x70cb1,0x8(%r8)            ;   {metadata({type array int})} 
>   0x00007f64d0337ea0:   prefetchw 0x140(%r10) 
>   0x00007f64d0337ea8:   movl   $0x2,0xc(%r8) 
>   0x00007f64d0337eb0:   prefetchw 0x180(%r10)               ;*newarray {reexecute=0 rethrow=0 return_oop=0} 
>                                                             ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 4 (line 38) 
>   0x00007f64d0337eb8:   mov    0x14(%rbp),%r11d             ;*getfield i3 {reexecute=0 rethrow=0 return_oop=0} 
>                                                             ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 16 (line 38) 
>   0x00007f64d0337ebc:   mov    0xc(%rbp),%r10d              ;*getfield i1 {reexecute=0 rethrow=0 return_oop=0} 
>                                                             ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 9 (line 38) 
>   0x00007f64d0337ec0:   mov    %r10d,0x10(%r8)              ;*iastore {reexecute=0 rethrow=0 return_oop=0} 
>                                                             ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 12 (line 38) 
>   0x00007f64d0337ec4:   mov    %r11d,0x14(%r8) 
>   0x00007f64d0337ec8:   mov    0x120(%r15),%rax             ;*invokestatic extract {reexecute=0 rethrow=0 return_oop=0} 
>                                                             ; - jdk.incubator.vector.Int64Vector::laneHelper at 16 (line 482) 
>                                                             ; - jdk.incubator.vector.Int64Vector::lane at 36 (line 476) 
>                                                             ; - fr.umlv.vector.VectorizedHashCode$Data::hashCode2 at 66 (line 41) 
>   0x00007f64d0337ecf:   vmovq  0x10(%r8),%xmm1              ;*invokestatic load {reexecute=0 rethrow=0 return_oop=0}
> 
> cheers,
> Rémi
> 
> 
> 
> Paul.
> 
> On May 11, 2020, at 12:59 PM, forax at univ-mlv.fr <mailto:forax at univ-mlv.fr> wrote:
> 
> My recommendation would be to use fromValues for constant or pre-computed vector
> values.
> 
> and what i should use for fields ?
> 
> Adding pattern matching rules for that in HS can not be done ?
> 
> vmovq + vpxor => vpxor
> vpinsrd + vpxor => vpxor,
> etc
> 
> 
>