Reduce latency with a few precompiles (#863)

Author: timholy

src/StaticArrays.jl

@@ -144,4 +144,9 @@ include("deque.jl")
 include("flatten.jl")
 include("io.jl")
 
+if Base.VERSION >= v"1.4.2"
+    include("precompile.jl")
+    _precompile_()
+end
+
 end # module

src/precompile.jl

@@ -0,0 +1,28 @@
+function _precompile_()
+    ccall(:jl_generating_output, Cint, ()) == 1 || return nothing
+    # These make a difference for Makie's TTFP and should help others too
+    # Total time for this to run is ~2s. To time it, disable:
+    #   - the `_precompile_()` call in StaticArrays.jl
+    #   - the jl_generating_output line above
+    # and then do
+    #     @time StaticArrays._precompile_()
+
+    for T in (Float32, Float64, Int)   # some common eltypes
+        for S = 2:4                    # some common sizes
+            L = S*S
+            @assert precompile(Tuple{typeof(*),SMatrix{S, S, T, L},SMatrix{S, S, T, L}})
+            @assert precompile(Tuple{typeof(inv),SMatrix{S, S, T, L}})
+            @assert precompile(Tuple{typeof(transpose),SMatrix{S, S, T, L}})
+            @assert precompile(Tuple{typeof(_adjoint),Size{(S, S)},SMatrix{S, S, T, L}})
+            @assert precompile(Tuple{Core.kwftype(typeof(minimum)),NamedTuple{(:dims,), Tuple{Int}},typeof(minimum),SMatrix{S, S, T, L}})
+            @assert precompile(Tuple{Core.kwftype(typeof(maximum)),NamedTuple{(:dims,), Tuple{Int}},typeof(maximum),SMatrix{S, S, T, L}})
+            @assert precompile(Tuple{typeof(getindex),SMatrix{S, S, T, L},SOneTo{S-1},SOneTo{S-1}})
+        end
+    end
+
+    # Some expensive generators
+    @assert precompile(Tuple{typeof(which(_broadcast,(Any,Size,Tuple{Vararg{Size}},Vararg{Any},)).generator.gen),Any,Any,Any,Any,Any,Any})
+    @assert precompile(Tuple{typeof(which(_zeros,(Size,Type{<:StaticArray},)).generator.gen),Any,Any,Any,Type,Any})
+    @assert precompile(Tuple{typeof(which(combine_sizes,(Tuple{Vararg{Size}},)).generator.gen),Any,Any})
+    @assert precompile(Tuple{typeof(which(_mapfoldl,(Any,Any,Colon,Any,Size,Vararg{StaticArray},)).generator.gen),Any,Any,Any,Any,Any,Any,Any,Any})
+end