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Fix integer overflow in the generic matmul kernels. #746

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Merged
maleadt merged 1 commit into from
Jun 24, 2026
Merged

Fix integer overflow in the generic matmul kernels. #746

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54 changes: 31 additions & 23 deletions src/host/linalg.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -459,9 +459,10 @@ function generic_matmatmul!(C::AbstractArray{R}, A::AbstractArray{T}, B::Abstrac

@inbounds if i <= size(A,1) && j <= size(B,2)
z2 = zero(A[i, 1]*B[1, j] + A[i, 1]*B[1, j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
for k in 1:size(A,2)
Cij += A[i, k]*B[k, j]
Cij += convert(Tacc, A[i, k]) * convert(Tacc, B[k, j])
end
C[i,j] = add(Cij, C[i,j])
end
Expand Down Expand Up @@ -511,10 +512,11 @@ function _triangular_matmatmul!(C::AbstractGPUVecOrMat{R}, A::AbstractTriangular

@inbounds if i <= l && j <= n
z2 = zero(A[i, 1]*B[1, j] + A[i, 1]*B[1, j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Cij += A[i,i] * B[i,j]
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
Cij += convert(Tacc, A[i,i]) * convert(Tacc, B[i,j])
for k in (upperA ? (i + 1) : 1):(upperA ? m : (i - 1))
Cij += A[i,k] * B[k,j]
Cij += convert(Tacc, A[i,k]) * convert(Tacc, B[k,j])
end
# treat C as write-only when beta is zero (it may hold NaN/Inf)
C[i,j] = iszero(beta) ? alpha * Cij : alpha * Cij + beta * C[i,j]
Expand Down Expand Up @@ -596,10 +598,11 @@ function generic_trimatmul!(C::AbstractGPUVecOrMat{R}, uploc, isunitc, tfun::Fun

@inbounds if i <= l && j <= n
z2 = zero(A[i,1] * B[1,j] + A[i,1] * B[1,j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Cij += (unit ? one(Cij) : A[i,i]) * B[i,j]
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
Cij += (unit ? one(Cij) : convert(Tacc, A[i,i])) * convert(Tacc, B[i,j])
for k in (upper ? (i + 1) : 1):(upper ? m : (i - 1))
Cij += A[i,k] * B[k,j]
Cij += convert(Tacc, A[i,k]) * convert(Tacc, B[k,j])
end
C[i,j] += Cij
end
Expand All @@ -613,10 +616,11 @@ function generic_trimatmul!(C::AbstractGPUVecOrMat{R}, uploc, isunitc, tfun::Fun

@inbounds if i <= l && j <= n
z2 = zero(A[i,1] * B[1,j] + A[i,1] * B[1,j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Cij += (unit ? one(Cij) : transpose(A[i,i])) * B[i,j]
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
Cij += (unit ? one(Cij) : transpose(convert(Tacc, A[i,i]))) * convert(Tacc, B[i,j])
for k in (upper ? (i + 1) : 1):(upper ? m : (i - 1))
Cij += transpose(A[k,i]) * B[k,j]
Cij += transpose(convert(Tacc, A[k,i])) * convert(Tacc, B[k,j])
end
C[i,j] += Cij
end
Expand All @@ -630,10 +634,11 @@ function generic_trimatmul!(C::AbstractGPUVecOrMat{R}, uploc, isunitc, tfun::Fun

@inbounds if i <= l && j <= n
z2 = zero(A[i,1] * B[1,j] + A[i,1] * B[1,j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Cij += (unit ? one(Cij) : adjoint(A[i,i])) * B[i,j]
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
Cij += (unit ? one(Cij) : adjoint(convert(Tacc, A[i,i]))) * convert(Tacc, B[i,j])
for k in (upper ? (i + 1) : 1):(upper ? m : (i - 1))
Cij += adjoint(A[k,i]) * B[k,j]
Cij += adjoint(convert(Tacc, A[k,i])) * convert(Tacc, B[k,j])
end
C[i,j] += Cij
end
Expand Down Expand Up @@ -674,10 +679,11 @@ function generic_mattrimul!(C::AbstractGPUVecOrMat{R}, uploc, isunitc, tfun::Fun

@inbounds if i <= l && j <= n
z2 = zero(A[i,1] * B[1,j] + A[i,1] * B[1,j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Cij += A[i,j] * (unit ? one(Cij) : B[j,j])
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
Cij += convert(Tacc, A[i,j]) * (unit ? one(Cij) : convert(Tacc, B[j,j]))
for k in (upper ? 1 : (j + 1)):(upper ? (j - 1) : m)
Cij += A[i,k] * B[k,j]
Cij += convert(Tacc, A[i,k]) * convert(Tacc, B[k,j])
end
C[i,j] += Cij
end
Expand All @@ -691,10 +697,11 @@ function generic_mattrimul!(C::AbstractGPUVecOrMat{R}, uploc, isunitc, tfun::Fun

@inbounds if i <= l && j <= n
z2 = zero(A[i,1] * B[1,j] + A[i,1] * B[1,j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Cij += A[i,j] * (unit ? one(Cij) : transpose(B[j,j]))
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
Cij += convert(Tacc, A[i,j]) * (unit ? one(Cij) : transpose(convert(Tacc, B[j,j])))
for k in (upper ? 1 : (j + 1) ):(upper ? (j - 1) : m)
Cij += A[i,k] * transpose(B[j,k])
Cij += convert(Tacc, A[i,k]) * transpose(convert(Tacc, B[j,k]))
end
C[i,j] += Cij
end
Expand All @@ -708,10 +715,11 @@ function generic_mattrimul!(C::AbstractGPUVecOrMat{R}, uploc, isunitc, tfun::Fun

@inbounds if i <= l && j <= n
z2 = zero(A[i,1] * B[1,j] + A[i,1] * B[1,j])
Cij = convert(promote_type(R, typeof(z2)), z2)
Cij += A[i,j] * (unit ? one(Cij) : adjoint(B[j,j]))
Tacc = promote_type(R, typeof(z2))
Cij = convert(Tacc, z2)
Cij += convert(Tacc, A[i,j]) * (unit ? one(Cij) : adjoint(convert(Tacc, B[j,j])))
for k in (upper ? 1 : (j + 1)):(upper ? (j - 1) : m)
Cij += A[i,k] * adjoint(B[j,k])
Cij += convert(Tacc, A[i,k]) * adjoint(convert(Tacc, B[j,k]))
end
C[i,j] += Cij
end
Expand Down
27 changes: 26 additions & 1 deletion test/testsuite/linalg.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -193,7 +193,7 @@
A = AT(rand(T, n, n))
B = AT(rand(T, n, n))
Ct = AT(rand(T, n, n))
C = collect(Ct)
C = collect(Ct)
mul!(Ct, TR1(A), TR2(B), 1, -1)
mul!(C, TR1(collect(A)), TR2(collect(B)), 1, -1)
@test collect(Ct) ≈ C
Expand Down Expand Up @@ -576,6 +576,31 @@ end
end
end

@testsuite "linalg/mul!/integer-accumulate" (AT, eltypes)->begin
# products must be formed in the wide accumulator type, not the narrow input type, else
# narrow-integer products overflow.
gpu = AT <: AbstractGPUArray
@testset "$Tin -> $Tout" for (Tin, Tout) in ((Int16, Int32), (Int16, Int64), (Int32, Int64))
Tin in eltypes || continue
n = 16
hi = Tin(4) * isqrt(typemax(Tin)) # |a*b| reliably exceeds typemax(Tin)
rng = (-hi):hi
A, B, x = rand(rng, n, n), rand(rng, n, n), rand(rng, n)
dA, dB, dx = AT(A), AT(B), AT(x)

if gpu || VERSION >= v"1.11"
C = AT(zeros(Tout, n, n))
mul!(C, dA, dB)
@test Array(C) == Tout.(Int64.(A) * Int64.(B))
end
if gpu # JuliaLang/LinearAlgebra.jl#1659
c = AT(zeros(Tout, n))
mul!(c, dA, dx)
@test Array(c) == Tout.(Int64.(A) * Int64.(x))
end
end
end

@testsuite "linalg/norm" (AT, eltypes)->begin
@testset "$p-norm($sz x $T)" for sz in [(2,), (2,0), (2,2,2)],
p in Any[0, 0.5, 1, 1.5, 2, Inf, -Inf],
Expand Down
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