diff --git a/src/codegen/forward.jl b/src/codegen/forward.jl
index 21c4f8ae..a2169466 100644
--- a/src/codegen/forward.jl
+++ b/src/codegen/forward.jl
@@ -1,17 +1,23 @@
-function transform_fwd!(ci, meth, nargs, sparams, N)
+function fwd_transform(ci, args...)
+    newci = copy(ci)
+    fwd_transform!(newci, args...)
+    return newci
+end
+
+function fwd_transform!(ci, mi, nargs, N)
     new_code = Any[]
     new_codelocs = Any[]
     ssa_mapping = Int[]
     loc_mapping = Int[]
 
-    function emit!(stmt)
+    function emit!(@nospecialize stmt)
         (isexpr(stmt, :call) || isexpr(stmt, :(=)) || isexpr(stmt, :new)) || return stmt
         push!(new_code, stmt)
         push!(new_codelocs, isempty(new_codelocs) ? 0 : new_codelocs[end])
-        SSAValue(length(new_code))
+        return SSAValue(length(new_code))
     end
 
-    function mapstmt!(stmt)
+    function mapstmt!(@nospecialize stmt)
         if isexpr(stmt, :(=))
             return Expr(stmt.head, emit!(mapstmt!(stmt.args[1])), emit!(mapstmt!(stmt.args[2])))
         elseif isexpr(stmt, :call)
@@ -44,7 +50,7 @@ function transform_fwd!(ci, meth, nargs, sparams, N)
         elseif isa(stmt, GotoIfNot)
             return GotoIfNot(emit!(Expr(:call, primal, emit!(mapstmt!(stmt.cond)))), stmt.dest)
         elseif isexpr(stmt, :static_parameter)
-            return ZeroBundle{N}(sparams[stmt.args[1]])
+            return ZeroBundle{N}(mi.sparam_vals[stmt.args[1]::Int])
         elseif isexpr(stmt, :foreigncall)
             return Expr(:call, error, "Attempted to AD a foreigncall. Missing rule?")
         elseif isexpr(stmt, :meta) || isexpr(stmt, :inbounds)
@@ -56,9 +62,11 @@ function transform_fwd!(ci, meth, nargs, sparams, N)
         end
     end
 
-    for i = 1:meth.nargs
-        if meth.isva && i == meth.nargs
-            args = map(i:(nargs+1)) do j
+    meth = mi.def::Method
+    nargs = Int(meth.nargs)
+    for i = 1:nargs
+        if meth.isva && i == nargs
+            args = map(i:(nargs+1)) do j::Int
                 emit!(Expr(:call, getfield, SlotNumber(2), j))
             end
             emit!(Expr(:(=), SlotNumber(2 + i), Expr(:call, ∂vararg{N}(), args...)))
@@ -83,7 +91,15 @@ function transform_fwd!(ci, meth, nargs, sparams, N)
         end
     end
 
+    ci.slotnames = Symbol[Symbol("#self#"), :args, ci.slotnames...]
+    ci.slotflags = UInt8[0x00, 0x00, ci.slotflags...]
+    ci.slottypes = ci.slottypes === nothing ? nothing : Any[Any, Any, ci.slottypes...]
     ci.code = new_code
     ci.codelocs = new_codelocs
-    ci
+    ci.ssavaluetypes = length(new_code)
+    ci.ssaflags = UInt8[0 for i=1:length(new_code)]
+    ci.method_for_inference_limit_heuristics = meth
+    ci.edges = MethodInstance[mi]
+
+    return ci
 end
diff --git a/src/stage1/generated.jl b/src/stage1/generated.jl
index bb127c6e..5ccd1a81 100644
--- a/src/stage1/generated.jl
+++ b/src/stage1/generated.jl
@@ -23,12 +23,7 @@ function perform_optic_transform(world::UInt, source::LineNumberNode,
     mi = Core.Compiler.specialize_method(match)
     ci = Core.Compiler.retrieve_code_info(mi, world)
 
-    ci′ = copy(ci)
-    ci′.edges = MethodInstance[mi]
-
-    ci′ = diffract_transform!(ci′, mi.def, length(args) - 1, match.sparams, N)
-
-    return ci′
+    return optic_transform(ci, mi, length(args)-1, N)
 end
 
 # This relies on PartialStruct to infer well
diff --git a/src/stage1/recurse.jl b/src/stage1/recurse.jl
index 478fc174..08571289 100644
--- a/src/stage1/recurse.jl
+++ b/src/stage1/recurse.jl
@@ -256,8 +256,16 @@ function sptypes(sparams)
     end
 end
 
-function diffract_transform!(ci, meth, nargs, sparams, N)
+function optic_transform(ci, args...)
+    newci = copy(ci)
+    optic_transform!(newci, args...)
+    return newci
+end
+
+function optic_transform!(ci, mi, nargs, N)
     code = ci.code
+    sparams = mi.sparam_vals
+
     cfg = compute_basic_blocks(code)
     ci.slotnames = Symbol[Symbol("#self#"), :args, ci.slotnames...]
     ci.slotflags = UInt8[0x00, 0x00, ci.slotflags...]
@@ -270,13 +278,15 @@ function diffract_transform!(ci, meth, nargs, sparams, N)
         Any[Any for i = 1:2], meta, sptypes(sparams))
 
     # SSA conversion
+    meth = mi.def::Method
     domtree = construct_domtree(ir.cfg.blocks)
     defuse_insts = scan_slot_def_use(Int(meth.nargs), ci, ir.stmts.inst)
     ci.ssavaluetypes = Any[Any for i = 1:ci.ssavaluetypes]
     ir = construct_ssa!(ci, ir, domtree, defuse_insts, ci.slottypes, Core.Compiler.OptimizerLattice())
     ir = compact!(ir)
 
-    nfixedargs = meth.isva ? meth.nargs - 1 : meth.nargs
+    nfixedargs = Int(meth.nargs)
+    meth.isva && (nfixedargs -= 1)
     meth.isva || @assert nfixedargs == nargs+1
 
     ir = diffract_ir!(ir, ci, meth, sparams, nargs, N)
@@ -286,6 +296,7 @@ function diffract_transform!(ci, meth, nargs, sparams, N)
     ci.ssavaluetypes = length(ci.code)
     ci.ssaflags = UInt8[0x00 for i=1:length(ci.code)]
     ci.method_for_inference_limit_heuristics = meth
+    ci.edges = MethodInstance[mi]
 
     return ci
 end
diff --git a/src/stage1/recurse_fwd.jl b/src/stage1/recurse_fwd.jl
index c9c7172b..58572e6c 100644
--- a/src/stage1/recurse_fwd.jl
+++ b/src/stage1/recurse_fwd.jl
@@ -47,22 +47,7 @@ function perform_fwd_transform(world::UInt, source::LineNumberNode,
     mi = Core.Compiler.specialize_method(match)
     ci = Core.Compiler.retrieve_code_info(mi, world)
 
-    ci′ = copy(ci)
-    ci′.edges = MethodInstance[mi]
-
-    transform_fwd!(ci′, mi.def, length(args) - 1, match.sparams, N)
-
-    ci′.ssavaluetypes = length(ci′.code)
-    ci′.ssaflags = UInt8[0 for i=1:length(ci′.code)]
-    ci′.method_for_inference_limit_heuristics = match.method
-    slotnames = Symbol[Symbol("#self#"), :args, ci.slotnames...]
-    slotflags = UInt8[(0x00 for i = 1:2)..., ci.slotflags...]
-    slottypes = ci.slottypes === nothing ? nothing : Any[(Any for i = 1:2)..., ci.slottypes...]
-    ci′.slotnames = slotnames
-    ci′.slotflags = slotflags
-    ci′.slottypes = slottypes
-
-    return ci′
+    return fwd_transform(ci, mi, length(args)-1, N)
 end
 
 let ex = :(function (ff::∂☆recurse)(args...)