AVX2 ∧ and ∨ with intermediate row sizes (64≤l<160)

This commit is contained in:
Marshall Lochbaum 2025-02-23 19:19:46 -05:00
parent 94e6b6cb3a
commit 1fef51a39e

View File

@ -350,6 +350,9 @@ fn scan_rows_andor{id}(src:*u64, dst:*u64, nl:usz, l:usz) : void = {
if (qand) x &~ ((x+c) & (x+m))
else x | ((-x-c) &~ (x-m))
}
def apply_carry{s, c, f} = {
if (qand) s & (~f | c) else s | (f & c)
}
if (l < 64) {
if ((l & (l-1)) == 0) {
if (l == 2) {
@ -363,9 +366,6 @@ fn scan_rows_andor{id}(src:*u64, dst:*u64, nl:usz, l:usz) : void = {
# could use for l>=8; not much faster and takes up space
# def rowwise{T} = @for (r in *T~~dst, x in *T~~src over (64/width{T})*nw) r = x &~ (x+1)
} else if (hasarch{'AVX2'}) {
def apply_carry{s, c, f} = {
if (qand) s & (~f | c) else s | (f & c)
}
avx2_loop_with_unaligned_mask{src, dst, nw, l, scan_mask, apply_carry}
} else {
loop_with_unaligned_mask{src, dst, nw, l, {x, c, m} => {
@ -376,14 +376,40 @@ fn scan_rows_andor{id}(src:*u64, dst:*u64, nl:usz, l:usz) : void = {
}}
}
} else if (l < 160) {
q:usz = 0 # distance to next row boundary
c:u64 = id # carry
@for (r in dst, x in src over nw) {
b:= q<64 # whether there's a boundary
p:= q%64 # its position
q-= 64 - (l &- b)
r = res_m1{x, c, promote{u64, b} << p}
c = r >> 63
if (hasarch{'AVX2'}) {
assert{l >= 64}
def V = [4]u64
c := V**id # carry, 0 or 1
v1:= V**1; xk:= c - v1
q := -make{V, 64*iota{4}} # distance to next row boundary
def q_mod{} = { q = blend_top{q,q+V**l, q} }
o:u64 = 256; while (o>l) { o-=l; q_mod{} }
@for_masked{4} (x in tup{V, src}, r in tup{V, dst} over nw) {
# Get mask; <=1 bit per word
m:= v1 << q
q-= V**o; q_mod{}
# Within-word scan and carry info
r = (if (qand) x &~ ((x+v1) & (x+m))
else x | ((-x) &~ (x-m)))
p:= (if (qand) x&~m else x|m) == xk
k:= r>>63 | p # Carry of 0 or 1, but -1 to propagate previous
# Propagate carries and adjust result
def bl{b,a} = blend_top{b,a, b}
k = bl{make_scan_idem{f64, bl}{k}, c} # Can't be -1 now
t:= blend{shuf{V, k, 3,0,1,2}, c, 1,0,0,0}
r = apply_carry{r, -t, m-v1}
c = shuf{V, k, 4**3}
}
} else {
q:usz = 0 # distance to next row boundary
c:u64 = id # carry
@for (r in dst, x in src over nw) {
b:= q<64 # whether there's a boundary
p:= q%64 # its position
q-= 64 - (l &- b)
r = res_m1{x, c, promote{u64, b} << p}
c = r >> 63
}
}
} else {
i :usz = 0 # row bit index