Remove allocations in lsr1 push! (#388)

* remove allocations in lsr1 push!

* add allocation test for push!

Author: MaxenceGollier

src/lsr1.jl

@@ -161,12 +161,12 @@ function push!(op::LSR1Operator, s::AbstractVector, y::AbstractVector)
   for i = 1:(data.mem)
     k = mod(data.insert + i - 2, data.mem) + 1
     if data.ys[k] != 0
-      data.a[k] .= data.y[k] - data.s[k] / data.scaling_factor  # = y - B₀ * s
+      @. data.a[k] = data.y[k] - data.s[k] / data.scaling_factor  # = y - B₀ * s
       for j = 1:(i - 1)
         l = mod(data.insert + j - 2, data.mem) + 1
         if data.ys[l] != 0
           as = dot(data.a[l], data.s[k]) / data.as[l]
-          data.a[k] .-= as * data.a[l]
+          @. data.a[k] -= as * data.a[l]
         end
       end
       data.as[k] = dot(data.a[k], data.s[k])

test/test_lsr1.jl

@@ -83,11 +83,13 @@ function test_lsr1()
     n = 100
     mem = 20
     B = LSR1Operator(n, mem = mem)
+    nallocs = 0
     for _ = 1:2:n
       s = rand(n)
       y = rand(n)
-      push!(B, s, y)
+      nallocs += @allocated push!(B, s, y)
     end
+    @test nallocs == 0
     x = rand(n)
     res = similar(x)
     mul!(res, B, x)  # warmup