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Merge pull request #1619 from tgruben/bounds-check

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removing bounds check
This commit is contained in:
tgruben 2018-09-24 13:22:37 -05:00 • committed by GitHub
commit 73fc1e660b
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 83 additions and 31 deletions
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110
roaring/roaring.go
View file

@ -2139,15 +2139,25 @@ func intersectArrayBitmap(a, b *Container) *Container {
}
func intersectBitmapBitmap(a, b *Container) *Container {
output := &Container{bitmap: make([]uint64, bitmapN), containerType: containerBitmap}
for i := range a.bitmap {
v := a.bitmap[i] & b.bitmap[i]
output.bitmap[i] = v
output.n += int(popcount(v))
// local variables added to prevent BCE checks in loop
// see https://go101.org/article/bounds-check-elimination.html
var (
ab = a.bitmap[:bitmapN]
bb = b.bitmap[:bitmapN]
buf = make([]uint64, bitmapN)
ob = buf[:bitmapN]
n int
)
for i := 0; i < bitmapN; i++ {
ob[i] = ab[i] & bb[i]
n += int(popcount(ob[i]))
}
output := &Container{
bitmap: ob,
n: n,
containerType: containerBitmap,
}
output.optimize()
return output
}
@ -2437,17 +2447,28 @@ func unionArrayBitmap(a, b *Container) *Container {
}
func unionBitmapBitmap(a, b *Container) *Container {
output := &Container{
bitmap: make([]uint64, bitmapN),
containerType: containerBitmap,
}
// local variables added to prevent BCE checks in loop
// see https://go101.org/article/bounds-check-elimination.html
var (
ab = a.bitmap[:bitmapN]
bb = b.bitmap[:bitmapN]
buf = make([]uint64, bitmapN)
ob = buf[:bitmapN]
n int
)
for i := 0; i < bitmapN; i++ {
v := a.bitmap[i] | b.bitmap[i]
output.bitmap[i] = v
output.n += int(popcount(v))
ob[i] = ab[i] | bb[i]
n += int(popcount(ob[i]))
}
output := &Container{
bitmap: ob,
n: n,
containerType: containerBitmap,
}
return output
}
@ -2783,13 +2804,27 @@ func differenceBitmapArray(a, b *Container) *Container {
}
func differenceBitmapBitmap(a, b *Container) *Container {
output := &Container{bitmap: make([]uint64, bitmapN), containerType: containerBitmap}
// local variables added to prevent BCE checks in loop
// see https://go101.org/article/bounds-check-elimination.html
for i := range a.bitmap {
v := a.bitmap[i] & (^b.bitmap[i])
output.bitmap[i] = v
output.n += int(popcount(v))
var (
ab = a.bitmap[:bitmapN]
bb = b.bitmap[:bitmapN]
buf = make([]uint64, bitmapN)
ob = buf[:bitmapN]
n int
)
for i := 0; i < bitmapN; i++ {
ob[i] = ab[i] & (^bb[i])
n += int(popcount(ob[i]))
}
output := &Container{
bitmap: ob,
n: n,
containerType: containerBitmap,
}
if output.n < ArrayMaxSize {
output.bitmapToArray()
@ -2874,16 +2909,28 @@ func xorArrayBitmap(a, b *Container) *Container {
}
func xorBitmapBitmap(a, b *Container) *Container {
output := &Container{
bitmap: make([]uint64, bitmapN),
containerType: containerBitmap,
}
// local variables added to prevent BCE checks in loop
// see https://go101.org/article/bounds-check-elimination.html
var (
ab = a.bitmap[:bitmapN]
bb = b.bitmap[:bitmapN]
buf = make([]uint64, bitmapN)
ob = buf[:bitmapN]
n int
)
for i := 0; i < bitmapN; i++ {
v := a.bitmap[i] ^ b.bitmap[i]
output.bitmap[i] = v
output.n += int(popcount(v))
ob[i] = ab[i] ^ bb[i]
n += int(popcount(ob[i]))
}
output := &Container{
bitmap: ob,
n: n,
containerType: containerBitmap,
}
if output.count() < ArrayMaxSize {
output.bitmapToArray()
}
@ -3336,9 +3383,14 @@ func popcount(x uint64) uint64 {
}
func popcountAndSlice(s, m []uint64) uint64 {
var (
a = s[:bitmapN]
b = m[:bitmapN]
)
cnt := uint64(0)
for i := range s {
cnt += popcount(s[i] & m[i])
for i := 0; i < bitmapN; i++ {
cnt += popcount(a[i] & b[i])
}
return cnt
}

4
roaring/roaring_internal_test.go
View file

@ -784,11 +784,11 @@ func TestDifferenceMixed(t *testing.T) {
t.Fatalf("test #3 expected empty but got %v", res.runs)
}
c.bitmap = []uint64{0x64}
c.bitmap = MakeBitmap([]uint64{0x64})
c.n = c.countRange(0, 100)
c.containerType = containerBitmap
res = difference(c, a)
if !reflect.DeepEqual(res.bitmap, []uint64{0x4}) {
if !reflect.DeepEqual(res.bitmap, MakeBitmap([]uint64{0x4})) {
t.Fatalf("test #4 expected %v, but got %v", []uint16{4}, res.bitmap)
}