compiler: move NonConstGlobals pass to transform package

transform/globals.go

@@ -18,3 +18,16 @@ func ApplyFunctionSections(mod llvm.Module) {
 		llvmFn = llvm.NextFunction(llvmFn)
 	}
 }
+
+// NonConstGlobals turns all global constants into global variables. This works
+// around a limitation on Harvard architectures (e.g. AVR), where constant and
+// non-constant pointers point to a different address space. Normal pointer
+// behavior is restored by using the data space only, at the cost of RAM for
+// constant global variables.
+func NonConstGlobals(mod llvm.Module) {
+	global := mod.FirstGlobal()
+	for !global.IsNil() {
+		global.SetGlobalConstant(false)
+		global = llvm.NextGlobal(global)
+	}
+}