This package contains a macro for converting expressions to use muladd calls
Author JuliaDiffEq
5 Stars
Updated Last
12 Months Ago
Started In
July 2017


Build Status Build status Coverage Status

This package provides the @muladd macro. It automatically converts expressions with multiplications and additions or subtractions to calls with muladd which then fuse via FMA when it would increase the performance of the code. The @muladd macro can be placed on code blocks and it will automatically find the appropriate expressions and nest muladd expressions when necessary. In mixed expressions summands without multiplication will be grouped together and evaluated first but otherwise the order of evaluation of multiplications and additions is not changed.


julia> @macroexpand(@muladd k3 = f(t + c3*dt, @. uprev+dt*(a031*k1+a032*k2)))
:(k3 = f((muladd)(c3, dt, t), (muladd).(dt, (muladd).(a032, k2, (*).(a031, k1)), uprev)))

julia> @macroexpand(@muladd integrator.EEst = integrator.opts.internalnorm((update - dt*(bhat1*k1 + bhat4*k4 + bhat5*k5 + bhat6*k6 + bhat7*k7 + bhat10*k10))./ @. (integrator.opts.abstol+max(abs(uprev),abs(u))*integrator.opts.reltol)))
:(integrator.EEst = (integrator.opts).internalnorm((muladd)(-dt, (muladd)(bhat10, k10, (muladd)(bhat7, k7, (muladd)(bhat6, k6, (muladd)(bhat5, k5, (muladd)(bhat4, k4, bhat1 * k1))))), update) ./ (muladd).(max.(abs.(uprev), abs.(u)), (integrator.opts).reltol, (integrator.opts).abstol)))


A muladd call will be broadcasted if both the * and the + or - are broadcasted. If either one is not broadcasted, then the expression will be converted to a non-dotted muladd.


Most of the credit goes to @fcard and @devmotion for building the first version and greatly refining the macro. These contributions are not directly shown as this was developed in Gitter chats and in the DiffEqBase.jl repository, but these two individuals did almost all of the work.