Add pow_fast now that it's in VectorizationBase's cost table

Author: chriselrod

src/modeling/costs.jl

@@ -238,6 +238,7 @@ const COST = Dict{Symbol,InstructionCost}(
     :exp10 => InstructionCost(-3.0,13.0,26.0,14),
     :expm1 => InstructionCost(-3.0,30.0,60.0,19),
     :(^) => InstructionCost(-3.0,200.0,400.0,26), # FIXME
+    :pow_fast => InstructionCost(-3.0,200.0,400.0,26), # FIXME
     :sin => InstructionCost(-3,30.0,60.0,23),
     :cos => InstructionCost(-3,27.0,60.0,26),
     :sincos => InstructionCost(-3,37.0,85.0,26),

src/parse/add_compute.jl

@@ -256,7 +256,7 @@ function add_compute!(
     # instr = instruction(first(ex.args))::Symbol
     instr = instruction!(ls, first(ex.args))::Instruction
     args = @view(ex.args[2:end])
-    if instr.instr === :(^) && length(args) == 2
+    if (instr.instr === :pow_fast || instr.instr === :(^)) && length(args) == 2
         arg2 = args[2]
         arg2 isa Number && return add_pow!(ls, var, args[1], arg2, elementbytes, position)
     end