Implement generic_mul! for Julia 1.12 (#639)

Author: michel2323

src/host/linalg.jl

@@ -417,6 +417,21 @@ end
     function LinearAlgebra.generic_matmatmul_wrapper!(C::AbstractGPUMatrix{T}, tA::AbstractChar, tB::AbstractChar, A::AbstractGPUVecOrMat{T}, B::AbstractGPUVecOrMat{T}, alpha::Number, beta::Number, val::LinearAlgebra.BlasFlag.SyrkHerkGemm) where {T}
         LinearAlgebra.generic_matmatmul!(C, tA, tB, A, B, alpha, beta)
     end
+    # Julia 1.12 introduced generic_mul! for scalar * array operations
+    function LinearAlgebra.generic_mul!(C::AbstractGPUVecOrMat, X::AbstractGPUVecOrMat, s::Number, alpha::Number, beta::Number)
+        if length(C) != length(X)
+            throw(DimensionMismatch(lazy"first array has length $(length(C)) which does not match the length of the second, $(length(X))."))
+        end
+        @. C = X * s * alpha + C * beta
+        return C
+    end
+    function LinearAlgebra.generic_mul!(C::AbstractGPUVecOrMat, s::Number, X::AbstractGPUVecOrMat, alpha::Number, beta::Number)
+        if length(C) != length(X)
+            throw(DimensionMismatch(lazy"first array has length $(length(C)) which does not match the length of the second, $(length(X))."))
+        end
+        @. C = s * X * alpha + C * beta
+        return C
+    end
 end
 
 function generic_trimatmul!(C::AbstractGPUVecOrMat{R}, uploc, isunitc, tfun::Function, A::AbstractGPUMatrix{T}, B::AbstractGPUVecOrMat{S}) where {T,S,R}
@@ -730,7 +745,7 @@ function LinearAlgebra.rotate!(x::AbstractGPUArray, y::AbstractGPUArray, c::Numb
         @inbounds xi = x[i]
         @inbounds yi = y[i]
         @inbounds x[i] = s*yi +      c *xi
-        @inbounds y[i] = c*yi - conj(s)*xi 
+        @inbounds y[i] = c*yi - conj(s)*xi
     end
     rotate_kernel!(get_backend(x))(x, y, c, s; ndrange = size(x))
     return x, y

test/testsuite/linalg.jl

@@ -256,17 +256,17 @@
                 B = Diagonal(b)
                 A = Diagonal(a)
                 mul!(C, A, B)
-                @test collect(C.diag) ≈ collect(A.diag) .* collect(B.diag) 
+                @test collect(C.diag) ≈ collect(A.diag) .* collect(B.diag)
                 a = AT(diagm(rand(elty, n)))
                 b = AT(diagm(rand(elty, n)))
                 C = Diagonal(d)
                 mul!(C, a, b)
-                @test collect(C) ≈ Diagonal(collect(a) * collect(b)) 
+                @test collect(C) ≈ Diagonal(collect(a) * collect(b))
                 a = transpose(AT(diagm(rand(elty, n))))
                 b = adjoint(AT(diagm(rand(elty, n))))
                 C = Diagonal(d)
                 mul!(C, a, b)
-                @test collect(C) ≈ Diagonal(collect(a) * collect(b)) 
+                @test collect(C) ≈ Diagonal(collect(a) * collect(b))
             end
         end
 
@@ -303,6 +303,42 @@
         end
     end
 
+    @testset "mul! + UniformScaling" begin
+        for elty in (Float32, ComplexF32)
+            n = 128
+            s = rand(elty)
+            I_s = UniformScaling(s)
+
+            # Test vector operations
+            a = AT(rand(elty, n))
+            b = AT(rand(elty, n))
+            b_copy = copy(b)
+
+            # Test mul!(a, I*s, b) - should compute a = s * b
+            mul!(a, I_s, b)
+            @test collect(a) ≈ s .* collect(b_copy)
+
+            # Test mul!(a, b, s) - should compute a = b * s
+            a = AT(rand(elty, n))
+            mul!(a, b, s)
+            @test collect(a) ≈ collect(b_copy) .* s
+
+            # Test matrix operations
+            A = AT(rand(elty, n, n))
+            B = AT(rand(elty, n, n))
+            B_copy = copy(B)
+
+            # Test mul!(A, I*s, B)
+            mul!(A, I_s, B)
+            @test collect(A) ≈ s .* collect(B_copy)
+
+            # Test mul!(A, B, s)
+            A = AT(rand(elty, n, n))
+            mul!(A, B, s)
+            @test collect(A) ≈ collect(B_copy) .* s
+        end
+    end
+
     @testset "lmul! and rmul!" for (a,b) in [((3,4),(4,3)), ((3,), (1,3)), ((1,3), (3))], T in eltypes
         @test compare(rmul!, AT, rand(T, a), Ref(rand(T)))
         @test compare(lmul!, AT, Ref(rand(T)), rand(T, b))