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follow-up to hashing BigInts; expand testing #58714

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Merged
merged 3 commits into from
Jun 11, 2025
Merged

follow-up to hashing BigInts; expand testing #58714

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cc52cf3
fix hashing issues
adienes Jun 11, 2025
4e53c2b
fix loop
adienes Jun 11, 2025
1ba1392
remove prints
adienes Jun 11, 2025
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22 changes: 12 additions & 10 deletions base/gmp.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -853,12 +853,16 @@ if Limb === UInt64 === UInt
using .Base: HASH_SECRET, hash_bytes, hash_finalizer

function hash_integer(n::BigInt, h::UInt)
iszero(n) && return hash_integer(0, h)
GC.@preserve n begin
s = n.size
h ⊻= (s < 0)

us = abs(s)
leading_zero_bytes = div(leading_zeros(unsafe_load(n.d, us)), 8)
hash_bytes(
Ptr{UInt8}(n.d),
8 * abs(s),
8 * us - leading_zero_bytes,
h,
HASH_SECRET
)
Expand Down Expand Up @@ -895,16 +899,14 @@ if Limb === UInt64 === UInt
h = hash_integer(pow, h)

h ⊻= (sz < 0)
leading_zero_bytes = div(leading_zeros(unsafe_load(x.d, asz)), 8)
trailing_zero_bytes = div(pow, 8)
GC.@preserve x begin
h = hash_bytes(
Ptr{UInt8}(x.d) + 8 * trailing_zero_bytes,
8 * (asz - trailing_zero_bytes),
h,
HASH_SECRET
)
end
return h
return hash_bytes(
Ptr{UInt8}(x.d) + trailing_zero_bytes,
8 * asz - (leading_zero_bytes + trailing_zero_bytes),
h,
HASH_SECRET
)
end
end
end
Expand Down
25 changes: 17 additions & 8 deletions base/hashing.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -78,21 +78,30 @@ function _hash_integer(
seed ⊻= (x < 0)
u = abs(x)

# always left-pad to multiple of 8 bytes
buflen = UInt(cld(top_set_bit(u), 64) * 8)
# always left-pad to full byte
buflen = UInt(max(cld(top_set_bit(u), 8), 1))
seed = seed ⊻ (hash_mix(seed ⊻ secret[1], secret[2]) ⊻ buflen)

a = zero(UInt64)
b = zero(UInt64)

if buflen ≤ 16
a = (UInt64(u % UInt32) << 32) |
UInt64((u >>> ((buflen - 4) * 8)) % UInt32)
if buflen ≥ 4
a = (UInt64(u % UInt32) << 32) |
UInt64((u >>> ((buflen - 4) * 8)) % UInt32)

delta = (buflen & 24) >>> (buflen >>> 3)
delta = (buflen & 24) >>> (buflen >>> 3)

b = (UInt64((u >>> (8 * delta)) % UInt32) << 32) |
UInt64((u >>> (8 * (buflen - 4 - delta))) % UInt32)
b = (UInt64((u >>> (8 * delta)) % UInt32) << 32) |
UInt64((u >>> (8 * (buflen - 4 - delta))) % UInt32)
else # buflen > 0
b0 = u % UInt8
b1 = (u >>> (8 * div(buflen, 2))) % UInt8
b2 = (u >>> (8 * (buflen - 1))) % UInt8
a = (UInt64(b0) << 56) |
(UInt64(b1) << 32) |
UInt64(b2)
end
else
a = (u >>> 8(buflen - 16)) % UInt
b = (u >>> 8(buflen - 8)) % UInt
Expand All @@ -112,9 +121,9 @@ function _hash_integer(
seed = hash_mix(l0 ⊻ secret[1], l1 ⊻ seed)
see1 = hash_mix(l2 ⊻ secret[2], l3 ⊻ see1)
see2 = hash_mix(l4 ⊻ secret[3], l5 ⊻ see2)
i -= 48
end
seed = seed ⊻ see1 ⊻ see2
i -= 48
end
if i > 16
l0 = u % UInt; u >>>= 64
Expand Down
26 changes: 18 additions & 8 deletions test/gmp.jl
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Expand Up @@ -811,14 +811,24 @@ end

@testset "hashing" begin
for i in 1:10:100
for shift in 0:3
bint = big(11)^i << shift
bfloat = float(bint)
@test (hash(bint) == hash(bfloat)) == (bint == bfloat)
@test hash(bint, Base.HASH_SEED) ==
@invoke(hash(bint::Real, Base.HASH_SEED))
@test Base.hash_integer(bint, Base.HASH_SEED) ==
@invoke(Base.hash_integer(bint::Integer, Base.HASH_SEED))
for shift in vcat(0:8, 9:8:81)
for sgn in (1, -1)
bint = sgn * (big(11)^i << shift)
bfloat = float(bint)
@test (hash(bint) == hash(bfloat)) == (bint == bfloat)
@test hash(bint, Base.HASH_SEED) ==
@invoke(hash(bint::Real, Base.HASH_SEED))
@test Base.hash_integer(bint, Base.HASH_SEED) ==
@invoke(Base.hash_integer(bint::Integer, Base.HASH_SEED))
end
end
end

bint = big(0)
bfloat = float(bint)
@test (hash(bint) == hash(bfloat)) == (bint == bfloat)
@test hash(bint, Base.HASH_SEED) ==
@invoke(hash(bint::Real, Base.HASH_SEED))
@test Base.hash_integer(bint, Base.HASH_SEED) ==
@invoke(Base.hash_integer(bint::Integer, Base.HASH_SEED))
end