Skip to content

Commit

Permalink
remove hand-coded methods for (U)Int128 on 32 bit systems (#53867)
Browse files Browse the repository at this point in the history 
I believe this code existed to work around bugs that LLVM used to have
with 128 bit numbers on 32 bit systems, but I'm not entirely sure.
  • Loading branch information
@oscardssmith
oscardssmith authored Apr 16, 2024
1 parent a82a28f commit 13d4f0e
Showing 1 changed file with 6 additions and 158 deletions.
164 changes: 6 additions & 158 deletions base/int.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -843,166 +843,14 @@ widemul(x::Bool,y::Number) = x * y
widemul(x::Number,y::Bool) = x * y


## wide multiplication, Int128 multiply and divide ##

if Core.sizeof(Int) == 4
function widemul(u::Int64, v::Int64)
local u0::UInt64, v0::UInt64, w0::UInt64
local u1::Int64, v1::Int64, w1::UInt64, w2::Int64, t::UInt64

u0 = u & 0xffffffff; u1 = u >> 32
v0 = v & 0xffffffff; v1 = v >> 32
w0 = u0 * v0
t = reinterpret(UInt64, u1) * v0 + (w0 >>> 32)
w2 = reinterpret(Int64, t) >> 32
w1 = u0 * reinterpret(UInt64, v1) + (t & 0xffffffff)
hi = u1 * v1 + w2 + (reinterpret(Int64, w1) >> 32)
lo = w0 & 0xffffffff + (w1 << 32)
return Int128(hi) << 64 + Int128(lo)
end

function widemul(u::UInt64, v::UInt64)
local u0::UInt64, v0::UInt64, w0::UInt64
local u1::UInt64, v1::UInt64, w1::UInt64, w2::UInt64, t::UInt64

u0 = u & 0xffffffff; u1 = u >>> 32
v0 = v & 0xffffffff; v1 = v >>> 32
w0 = u0 * v0
t = u1 * v0 + (w0 >>> 32)
w2 = t >>> 32
w1 = u0 * v1 + (t & 0xffffffff)
hi = u1 * v1 + w2 + (w1 >>> 32)
lo = w0 & 0xffffffff + (w1 << 32)
return UInt128(hi) << 64 + UInt128(lo)
end

function *(u::Int128, v::Int128)
u0 = u % UInt64; u1 = Int64(u >> 64)
v0 = v % UInt64; v1 = Int64(v >> 64)
lolo = widemul(u0, v0)
lohi = widemul(reinterpret(Int64, u0), v1)
hilo = widemul(u1, reinterpret(Int64, v0))
t = reinterpret(UInt128, hilo) + (lolo >>> 64)
w1 = reinterpret(UInt128, lohi) + (t & 0xffffffffffffffff)
return Int128(lolo & 0xffffffffffffffff) + reinterpret(Int128, w1) << 64
end

function *(u::UInt128, v::UInt128)
u0 = u % UInt64; u1 = UInt64(u>>>64)
v0 = v % UInt64; v1 = UInt64(v>>>64)
lolo = widemul(u0, v0)
lohi = widemul(u0, v1)
hilo = widemul(u1, v0)
t = hilo + (lolo >>> 64)
w1 = lohi + (t & 0xffffffffffffffff)
return (lolo & 0xffffffffffffffff) + UInt128(w1) << 64
end

function _setbit(x::UInt128, i)
# faster version of `return x | (UInt128(1) << i)`
j = i >> 5
y = UInt128(one(UInt32) << (i & 0x1f))
if j == 0
return x | y
elseif j == 1
return x | (y << 32)
elseif j == 2
return x | (y << 64)
elseif j == 3
return x | (y << 96)
end
return x
end
# Int128 multiply and divide
*(x::T, y::T) where {T<:Union{Int128,UInt128}} = mul_int(x, y)

function divrem(x::UInt128, y::UInt128)
iszero(y) && throw(DivideError())
if (x >> 64) % UInt64 == 0
if (y >> 64) % UInt64 == 0
# fast path: upper 64 bits are zero, so we can fallback to UInt64 division
q64, x64 = divrem(x % UInt64, y % UInt64)
return UInt128(q64), UInt128(x64)
else
# this implies y>x, so
return zero(UInt128), x
end
end
n = leading_zeros(y) - leading_zeros(x)
q = zero(UInt128)
ys = y << n
while n >= 0
# ys == y * 2^n
if ys <= x
x -= ys
q = _setbit(q, n)
if (x >> 64) % UInt64 == 0
# exit early, similar to above fast path
if (y >> 64) % UInt64 == 0
q64, x64 = divrem(x % UInt64, y % UInt64)
q |= q64
x = UInt128(x64)
end
return q, x
end
end
ys >>>= 1
n -= 1
end
return q, x
end
div(x::Int128, y::Int128) = checked_sdiv_int(x, y)
div(x::UInt128, y::UInt128) = checked_udiv_int(x, y)

function div(x::Int128, y::Int128)
(x == typemin(Int128)) & (y == -1) && throw(DivideError())
return Int128(div(BigInt(x), BigInt(y)))::Int128
end
div(x::UInt128, y::UInt128) = divrem(x, y)[1]

function rem(x::Int128, y::Int128)
return Int128(rem(BigInt(x), BigInt(y)))::Int128
end

function rem(x::UInt128, y::UInt128)
iszero(y) && throw(DivideError())
if (x >> 64) % UInt64 == 0
if (y >> 64) % UInt64 == 0
# fast path: upper 64 bits are zero, so we can fallback to UInt64 division
return UInt128(rem(x % UInt64, y % UInt64))
else
# this implies y>x, so
return x
end
end
n = leading_zeros(y) - leading_zeros(x)
ys = y << n
while n >= 0
# ys == y * 2^n
if ys <= x
x -= ys
if (x >> 64) % UInt64 == 0
# exit early, similar to above fast path
if (y >> 64) % UInt64 == 0
x = UInt128(rem(x % UInt64, y % UInt64))
end
return x
end
end
ys >>>= 1
n -= 1
end
return x
end

function mod(x::Int128, y::Int128)
return Int128(mod(BigInt(x), BigInt(y)))::Int128
end
else
*(x::T, y::T) where {T<:Union{Int128,UInt128}} = mul_int(x, y)

div(x::Int128, y::Int128) = checked_sdiv_int(x, y)
div(x::UInt128, y::UInt128) = checked_udiv_int(x, y)

rem(x::Int128, y::Int128) = checked_srem_int(x, y)
rem(x::UInt128, y::UInt128) = checked_urem_int(x, y)
end
rem(x::Int128, y::Int128) = checked_srem_int(x, y)
rem(x::UInt128, y::UInt128) = checked_urem_int(x, y)

# issue #15489: since integer ops are unchecked, they shouldn't check promotion
for op in (:+, :-, :*, :&, :|, :xor)
Expand Down

0 comments on commit 13d4f0e

Please sign in to comment.