Extend SSSE3 k/bool to k<32 using pairwise swaps

This commit is contained in:
Marshall Lochbaum 2024-08-07 22:03:55 -04:00
parent 696a23af9e
commit 7d7d36b354

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@ -291,25 +291,8 @@ exportT{'si_constrep', each{rep_const, dat_types}}
# Constant replicate on boolean
fn rep_const_bool{}(wv:usz, x:*u64, r:*u64, rlen:usz) : u1 = {
def has_pdep = hasarch{'BMI2'}
def has_pdep = 0 # Obselete, kept here for descriptiveness
if (wv > 32) return{0}
if (hasarch{'SSSE3'}) {
if (wv&1 == 0) {
p := ctz{wv | 8} # Power of two for second replicate
if (wv>>p == 1) {
rep_const_bool_ssse3_div8{wv, x, r, rlen}
} else {
tlen := rlen>>p
t := r + cdiv{rlen, 64} - cdiv{tlen, 64}
rep_const_bool{}(wv >>p, x, t, tlen)
rep_const_bool{}(usz~~1<<p, t, r, rlen)
}
return{1}
} else if (wv < 16) {
rep_const_bool_ssse3_odd{wv, x, r, rlen}
return{1}
}
}
if (not has_pdep and wv <= 8) return{0}
m:u64 = spaced_mask_of{wv}
xw:u64 = 0
@ -352,6 +335,24 @@ fn rep_const_bool{}(wv:usz, x:*u64, r:*u64, rlen:usz) : u1 = {
1
}
fn rep_const_bool{if hasarch{'SSSE3'}}(wv:usz, x:*u64, r:*u64, rlen:usz) : u1 = {
if (wv > 32) return{0}
if (wv&1 == 0) {
p := ctz{wv | 8} # Power of two for second replicate
if (wv>>p == 1) {
rep_const_bool_ssse3_div8{wv, x, r, rlen}
} else {
tlen := rlen>>p
t := r + cdiv{rlen, 64} - cdiv{tlen, 64}
rep_const_bool{}(wv >>p, x, t, tlen)
rep_const_bool{}(usz~~1<<p, t, r, rlen)
}
} else {
rep_const_bool_ssse3_odd{wv, x, r, rlen}
}
1
}
# Generalized flat transpose of iota{1<<length{bs}}
# select{tr_iota{bs}, x} sends bit i of x to position select{bs, i}
def tr_iota{...bs} = {
@ -445,8 +446,7 @@ def rep_const_bool_ssse3_odd{wv, x, r, rlen} = { # wv odd, wv<=15
ttab:*V = join{each{get_ttab, 2*iota{4} + 1}}
{t0, t4} := each{load{ttab + (wv & 6), .}, iota{2}}
m4 := V**0xf
def get_perm_x{i} = {
xv := load{*V~~x, i}
def perm_x{xv} = {
selV{t0, xv & m4} | selV{t4, V~~([8]u16~~xv>>4) & m4}
}
@ -455,7 +455,7 @@ def rep_const_bool_ssse3_odd{wv, x, r, rlen} = { # wv odd, wv<=15
# 3: dedicated loop
i:usz = 0; while (1) {
# 01234567 to 05316427 on each byte
xv := get_perm_x{i}; ++i
xv := perm_x{load{*V~~x, i}}; ++i
# Overhang from previous 64-bit elements
def ix = 64*slice{iota{3},1} // 3 # bits that overhang within a word
def ib = ix // 8 # byte index
@ -503,7 +503,7 @@ def rep_const_bool_ssse3_odd{wv, x, r, rlen} = { # wv odd, wv<=15
while (1) {
--q; if (q == 0) { q = wv
# Load and permute bytes
xv = get_perm_x{i}; ++i
xv = perm_x{load{*V~~x, i}}; ++i
# Bytes for overhang
xo = V~~((W~~xv & xom) >> (8 - wv))
xo += xo > V**0
@ -522,35 +522,42 @@ def rep_const_bool_ssse3_odd{wv, x, r, rlen} = { # wv odd, wv<=15
o := xo & mkV{255 * (iV%8 == 0)} # overhang
output{rv | o}
}
} else { # wv < 16
# 9, 11, 13, 15: shared constant computation and loop
# Initializers, relying on vl%wv == vl-wv in various ways
wV:= V**cast_i{u8,wv}
ind0 := (iota{V} < wV) + V**1 # mkV{iV >= k}
} else { # wv < 32
# 9 to 31: extend k*i % 8 transform to k*i % 128 by pairwise swaps
# Swap data goes in a pre-computed table
def swdat{k} = {
def bits = (k*iota{128} >> merge{0, replicate{1<<iota{7}, iota{7}}}) & 1
mkV{each{base{2, .}, split{8, bits}}}
}
swtab:*V = each{swdat, 9+2*iota{12}}
def swap_lens = reverse{1 << iota{4}}
swap_data := load{swtab, (wv>>1)-4}
swap_masks := each{{l} => selV{swap_data, mkV{l+iV%l}}, swap_lens}
# Every-k-bits mask, same as before
{m, d} := unaligned_spaced_mask_mod{wv}
mask0:= V~~make{W, m, m>>d|m<<(wv-d)}
iu:= iota{V} + V**cast_i{u8,vl-wv}; ia:= iu>=V**vl
ind_up := iu - (wV&ia)
ind_inc:= V**(wv <= vl) - ia
mask_sh:= d+d; if (mask_sh >= wv) mask_sh-= wv
mask := V~~make{W, m, m>>d|m<<(wv-d)}
mask_sh := d+d; if (mask_sh >= wv) mask_sh-= wv
# State
xv:V = V**0; o:=W**0; ind:=xv; mask:=xv
xv:V = V**0; o:=W**0
i:usz = 0; q:usz = 1
while (1) {
--q; if (q == 0) { q = wv
xv = get_perm_x{i}; ++i
ind = ind0
mask = mask0
} else {
ind = selV{ind, ind_up} + ind_inc
mask = V~~((W~~mask << (wv - mask_sh)) | (W~~mask >> mask_sh))
# Load xv, send bit i to position wv*i % 128
xv = load{*V~~x, i}; ++i
def swap_step{l, m} = {
xv = (xv & m) | (selV{xv, mkV{iV + (l-2*(iV&l))}} &~ m)
}
each{swap_step, swap_lens, swap_masks}
xv = perm_x{xv}
# Write wv vectors based on that
@for (wv) {
b := W~~(xv & mask)
mask = V~~((W~~mask << (wv - mask_sh)) | (W~~mask >> mask_sh))
rv:= V~~((b<<wv) - b)
# Handle overhang here; won't fit in a single vector
po:= o; o = b>>(64-wv)
ro:= [4]u32~~vshl{po, o, 1}
output{rv | V~~(ro + (ro > [4]u32**0))}
}
# Handle overhang here; won't fit in a single vector
b := W~~(selV{xv, ind} & mask)
rv:= V~~((b<<wv) - b)
po:= o; o = b>>(64-wv)
ro:= [4]u32~~vshl{po, o, 1}
output{rv | V~~(ro + (ro > [4]u32**0))}
}
}
flush{}