remove unused rotate_registers

Author: gretay-js

backend/amd64/proc.ml

@@ -140,10 +140,6 @@ let register_name ty r =
   | Float | Float32 | Vec128 | Valx2 ->
     float_reg_name.(r - first_available_register.(1))
 
-(* Pack registers starting at %rax so as to reduce the number of REX
-   prefixes and thus improve code density *)
-let rotate_registers = false
-
 (* Representation of hard registers by pseudo-registers *)
 
 let hard_int_reg =

backend/arm64/proc.ml

@@ -131,9 +131,6 @@ let register_name ty r =
     (* CR mslater: (SIMD) arm64 *)
     fatal_error "arm64: got valx2 register"
 
-(* CR gyorsh for xclerc: [rotate_registers] used in [coloring] on Mach,
-   but not in IRC on CFG. Are we dropping an optimization here? *)
-let rotate_registers = true
 
 (* Representation of hard registers by pseudo-registers *)
 

backend/proc.mli

@@ -26,7 +26,6 @@ val first_available_register: int array
 val register_name: Cmm.machtype_component -> int -> string
 val phys_reg: Cmm.machtype_component -> int -> Reg.t
 val gc_regs_offset : Reg.t -> int
-val rotate_registers: bool
 val precolored_regs : unit -> Reg.Set.t
 
 (* The number of stack slot classes may differ from the number of register classes.