From eec9252d166a6675002d86b00fdb142381488127 Mon Sep 17 00:00:00 2001
From: Chris Rackauckas <accounts@chrisrackauckas.com>
Date: Wed, 18 Aug 2021 16:36:43 -0400
Subject: [PATCH 1/4] start trying to precompile ModelingToolkit better
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```julia
using ModelingToolkit, OrdinaryDiffEq

function f()
      @parameters t σ ρ β
      @variables x(t) y(t) z(t)
      D = Differential(t)

      eqs = [D(D(x)) ~ σ*(y-x),
             D(y) ~ x*(ρ-z)-y,
             D(z) ~ x*y - β*z]

      @named sys = ODESystem(eqs)
      sys = ode_order_lowering(sys)

      u0 = [D(x) => 2.0,
            x => 1.0,
            y => 0.0,
            z => 0.0]

      p  = [σ => 28.0,
            ρ => 10.0,
            β => 8/3]

      tspan = (0.0,100.0)
      prob = ODEProblem(sys,u0,tspan,p,jac=true)
end

using SnoopCompile

tinf = @snoopi_deep f()
```

```julia
Before:
InferenceTimingNode: 8.138765/20.550152 on Core.Compiler.Timings.ROOT() with 821 direct children
InferenceTimingNode: 8.152606/20.643050 on Core.Compiler.Timings.ROOT() with 821 direct children

After:
InferenceTimingNode: 8.216759/17.715817 on Core.Compiler.Timings.ROOT() with 839 direct children
InferenceTimingNode: 8.272943/17.854555 on Core.Compiler.Timings.ROOT() with 840 direct children
```

only 2 seconds for now, but it's a start.
---
 src/ModelingToolkit.jl |  3 +++
 src/precompile.jl      | 28 ++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 src/precompile.jl

diff --git a/src/ModelingToolkit.jl b/src/ModelingToolkit.jl
index f46b500fb6..969ba43e7e 100644
--- a/src/ModelingToolkit.jl
+++ b/src/ModelingToolkit.jl
@@ -151,6 +151,9 @@ using .SystemStructures
 
 include("systems/alias_elimination.jl")
 include("structural_transformation/StructuralTransformations.jl")
+
+include("precompile.jl")
+
 @reexport using .StructuralTransformations
 
 for S in subtypes(ModelingToolkit.AbstractSystem)
diff --git a/src/precompile.jl b/src/precompile.jl
new file mode 100644
index 0000000000..c7ae5a9be5
--- /dev/null
+++ b/src/precompile.jl
@@ -0,0 +1,28 @@
+let
+    while true
+        @parameters t σ ρ β
+        @variables x(t) y(t) z(t)
+        D = Differential(t)
+
+        eqs = [D(D(x)) ~ σ*(y-x) + 0.000000000000135,
+               D(y) ~ x*(ρ-z)-y,
+               D(z) ~ x*y - β*z]
+
+        @named sys = ODESystem(eqs)
+        sys = ode_order_lowering(sys)
+
+        u0 = [D(x) => 2.0,
+              x => 1.0,
+              y => 0.0,
+              z => 0.0]
+
+        p  = [σ => 28.0,
+              ρ => 10.0,
+              β => 8/3]
+
+        tspan = (0.0,100.0)
+        prob = ODEProblem(sys,u0,tspan,p,jac=true)
+
+        break
+    end
+end

From 3c45aeaa73eeb2d285061c658860c4ced674d0af Mon Sep 17 00:00:00 2001
From: Christopher Rackauckas <accounts@chrisrackauckas.com>
Date: Tue, 1 Feb 2022 08:31:18 -0500
Subject: [PATCH 2/4] Update precompile.jl

---
 src/precompile.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/precompile.jl b/src/precompile.jl
index c7ae5a9be5..96e201d12c 100644
--- a/src/precompile.jl
+++ b/src/precompile.jl
@@ -9,7 +9,7 @@ let
                D(z) ~ x*y - β*z]
 
         @named sys = ODESystem(eqs)
-        sys = ode_order_lowering(sys)
+        sys = structural_simplify(sys)
 
         u0 = [D(x) => 2.0,
               x => 1.0,

From e12e97c6fcc84018f31705f8c61847af6959fa39 Mon Sep 17 00:00:00 2001
From: Yingbo Ma <mayingbo5@gmail.com>
Date: Tue, 1 Feb 2022 09:00:24 -0500
Subject: [PATCH 3/4] Move precompile.jl to the end

---
 src/ModelingToolkit.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/ModelingToolkit.jl b/src/ModelingToolkit.jl
index 969ba43e7e..42d4472741 100644
--- a/src/ModelingToolkit.jl
+++ b/src/ModelingToolkit.jl
@@ -152,8 +152,6 @@ using .SystemStructures
 include("systems/alias_elimination.jl")
 include("structural_transformation/StructuralTransformations.jl")
 
-include("precompile.jl")
-
 @reexport using .StructuralTransformations
 
 for S in subtypes(ModelingToolkit.AbstractSystem)
@@ -210,4 +208,6 @@ export modelingtoolkitize
 export @variables, @parameters
 export @named, @nonamespace, @namespace, extend, compose
 
+include("precompile.jl")
+
 end # module

From 33f1261a15044d8ba97cbe566ff351c5cedad2fc Mon Sep 17 00:00:00 2001
From: Chris Rackauckas <accounts@chrisrackauckas.com>
Date: Tue, 1 Feb 2022 09:27:50 -0500
Subject: [PATCH 4/4] once you hack the fun don't snack.

---
 src/precompile.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/precompile.jl b/src/precompile.jl
index 96e201d12c..802333975f 100644
--- a/src/precompile.jl
+++ b/src/precompile.jl
@@ -4,7 +4,7 @@ let
         @variables x(t) y(t) z(t)
         D = Differential(t)
 
-        eqs = [D(D(x)) ~ σ*(y-x) + 0.000000000000135,
+        eqs = [D(D(x)) ~ σ*(y-x) + x^0.000000000000135,
                D(y) ~ x*(ρ-z)-y,
                D(z) ~ x*y - β*z]