use aliasscope when user uses Const

Author: vchuravy

src/macros.jl

@@ -87,13 +87,14 @@ function transform_gpu!(def, constargs, force_inbounds, unsafe_indices)
             push!(let_constargs, :($arg = $constify($arg)))
         end
     end
+    has_constargs = !isempty(let_constargs)
     pushfirst!(def[:args], :__ctx__)
     new_stmts = Expr[]
     body = MacroTools.flatten(def[:body])
     # On 1.11 and later having this aliasscope causes issues
     # even with kernels that don't use `@Const` on arguments
     # See https://github.com/JuliaGPU/KernelAbstractions.jl/issues/652
-    # push!(new_stmts, Expr(:aliasscope))
+    has_constargs && push!(new_stmts, Expr(:aliasscope))
     if !unsafe_indices
         push!(new_stmts, :(__active_lane__ = $__validindex(__ctx__)))
     end
@@ -108,7 +109,7 @@ function transform_gpu!(def, constargs, force_inbounds, unsafe_indices)
     if force_inbounds
         push!(new_stmts, Expr(:inbounds, :pop))
     end
-    # push!(new_stmts, Expr(:popaliasscope))
+    has_constargs && push!(new_stmts, Expr(:popaliasscope))
     push!(new_stmts, :(return nothing))
     def[:body] = Expr(
         :let,
@@ -132,21 +133,22 @@ function transform_cpu!(def, constargs, force_inbounds)
             push!(let_constargs, :($arg = $constify($arg)))
         end
     end
+    has_constargs = !isempty(let_constargs)
     pushfirst!(def[:args], :__ctx__)
     new_stmts = Expr[]
     body = MacroTools.flatten(def[:body])
     # On 1.11 and later having this aliasscope causes issues
     # even with kernels that don't use `@Const` on arguments
     # See https://github.com/JuliaGPU/KernelAbstractions.jl/issues/652
-    # push!(new_stmts, Expr(:aliasscope))
+    has_constargs && push!(new_stmts, Expr(:aliasscope))
     if force_inbounds
         push!(new_stmts, Expr(:inbounds, true))
     end
     append!(new_stmts, split(emit_cpu, body.args))
     if force_inbounds
         push!(new_stmts, Expr(:inbounds, :pop))
     end
-    # push!(new_stmts, Expr(:popaliasscope))
+    has_constargs && push!(new_stmts, Expr(:popaliasscope))
     push!(new_stmts, :(return nothing))
     def[:body] = Expr(
         :let,