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// +build ignore
package main
import (
. "github.com/mmcloughlin/avo/build"
. "github.com/mmcloughlin/avo/operand"
. "github.com/mmcloughlin/avo/reg"
)
var unroll = 6
func main() {
TEXT("Dot", NOSPLIT, "func(x, y []float32) float32")
x := Mem{Base: Load(Param("x").Base(), GP64())}
y := Mem{Base: Load(Param("y").Base(), GP64())}
n := Load(Param("x").Len(), GP64())
// Allocate accumulation registers.
acc := make([]VecVirtual, unroll)
for i := 0; i < unroll; i++ {
acc[i] = YMM()
}
// Zero initialization.
for i := 0; i < unroll; i++ {
VXORPS(acc[i], acc[i], acc[i])
}
// Loop over blocks and process them with vector instructions.
blockitems := 8 * unroll
blocksize := 4 * blockitems
Label("blockloop")
CMPQ(n, U32(blockitems))
JL(LabelRef("tail"))
// Load x.
xs := make([]VecVirtual, unroll)
for i := 0; i < unroll; i++ {
xs[i] = YMM()
}
for i := 0; i < unroll; i++ {
VMOVUPS(x.Offset(32*i), xs[i])
}
// The actual FMA.
for i := 0; i < unroll; i++ {
VFMADD231PS(y.Offset(32*i), xs[i], acc[i])
}
ADDQ(U32(blocksize), x.Base)
ADDQ(U32(blocksize), y.Base)
SUBQ(U32(blockitems), n)
JMP(LabelRef("blockloop"))
// Process any trailing entries.
Label("tail")
tail := XMM()
VXORPS(tail, tail, tail)
Label("tailloop")
CMPQ(n, U32(0))
JE(LabelRef("reduce"))
xt := XMM()
VMOVSS(x, xt)
VFMADD231SS(y, xt, tail)
ADDQ(U32(4), x.Base)
ADDQ(U32(4), y.Base)
DECQ(n)
JMP(LabelRef("tailloop"))
// Reduce the lanes to one.
Label("reduce")
for i := 1; i < unroll; i++ {
VADDPS(acc[0], acc[i], acc[0])
}
result := acc[0].AsX()
top := XMM()
VEXTRACTF128(U8(1), acc[0], top)
VADDPS(result, top, result)
VADDPS(result, tail, result)
VHADDPS(result, result, result)
VHADDPS(result, result, result)
Store(result, ReturnIndex(0))
RET()
Generate()
}
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