Precompilation is cool, we should do more of it

Project.toml

@@ -12,6 +12,7 @@ LLVM = "929cbde3-209d-540e-8aea-75f648917ca0"
 Libdl = "8f399da3-3557-5675-b5ff-fb832c97cbdb"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 ObjectFile = "d8793406-e978-5875-9003-1fc021f44a92"
+PrecompileTools = "aea7be01-6a6a-4083-8856-8a6e6704d82a"
 Preferences = "21216c6a-2e73-6563-6e65-726566657250"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"

src/Enzyme.jl

@@ -1587,4 +1587,6 @@ Returns true if within autodiff, otherwise false.
 """
 @inline EnzymeCore.within_autodiff() = false
 
+include("precompile.jl")
+
 end # module

src/compiler/orcv2.jl

@@ -83,7 +83,7 @@ function define_absolute_symbol(jd, name)
     return false
 end
 
-function __init__()
+function setup_globals()
     opt_level = Base.JLOptions().opt_level
     if opt_level < 2
         optlevel = LLVM.API.LLVMCodeGenLevelNone
@@ -105,11 +105,6 @@ function __init__()
     dg = LLVM.CreateDynamicLibrarySearchGeneratorForProcess(prefix)
     LLVM.add!(jd_main, dg)
 
-    if Sys.iswindows() && Int === Int64
-        # TODO can we check isGNU?
-        define_absolute_symbol(jd_main, mangle(lljit, "___chkstk_ms"))
-    end
-
     es = ExecutionSession(lljit)
     try
         lctm = LLVM.LocalLazyCallThroughManager(triple(lljit), es)
@@ -120,6 +115,17 @@ function __init__()
         jit[] = CompilerInstance(lljit, nothing, nothing)
     end
 
+    jd_main, lljit
+end
+
+function __init__()
+    jd_main, lljit = setup_globals()
+
+    if Sys.iswindows() && Int === Int64
+        # TODO can we check isGNU?
+        define_absolute_symbol(jd_main, mangle(lljit, "___chkstk_ms"))
+    end
+
     hnd = unsafe_load(cglobal(:jl_libjulia_handle, Ptr{Cvoid}))
     for (k, v) in Compiler.JuliaGlobalNameMap
         ptr = unsafe_load(Base.reinterpret(Ptr{Ptr{Cvoid}}, Libdl.dlsym(hnd, k)))

src/precompile.jl

@@ -0,0 +1,13 @@
+using PrecompileTools: @setup_workload, @compile_workload
+
+@setup_workload begin
+    precompile_module = @eval module $(gensym())
+        f(x) = x^2
+    end
+
+    Compiler.JIT.setup_globals()
+
+    @compile_workload begin
+        Enzyme.autodiff(Reverse, precompile_module.f, Active(2.0))
+    end
+end