ocaml/asmcomp/alpha/scheduling.ml

68 lines
2.2 KiB
OCaml

(***********************************************************************)
(* *)
(* Objective Caml *)
(* *)
(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
(* *)
(* Copyright 1996 Institut National de Recherche en Informatique et *)
(* Automatique. Distributed only by permission. *)
(* *)
(***********************************************************************)
(* $Id$ *)
open Mach
(* The Digital Unix assembler does scheduling better than us.
However, the Linux-Alpha assembler does not do scheduling, so we do
a feeble attempt here. *)
class scheduler () as self =
inherit Schedgen.scheduler_generic () as super
(* Latencies (in cycles). Based on the 21064, with some poetic license. *)
method oper_latency = function
Ireload -> 3
| Iload(_, _) -> 3
| Iconst_symbol _ -> 3 (* turned into a load *)
| Iconst_float _ -> 3 (* turned into a load *)
| Iintop(Imul) -> 23
| Iintop_imm(Imul, _) -> 23
| Iaddf -> 6
| Isubf -> 6
| Imulf -> 6
| Idivf -> 63
| _ -> 2
(* Most arithmetic instructions can be executed back-to-back in 1 cycle.
However, some combinations (arith; load or arith; store) require 2
cycles. Also, by claiming 2 cycles instead of 1, we might favor
dual issue. *)
(* Issue cycles. Rough approximations. *)
method oper_issue_cycles = function
Ialloc _ -> 4
| Iintop(Icheckbound) -> 2
| Iintop_imm(Idiv, _) -> 3
| Iintop_imm(Imod, _) -> 5
| Iintop_imm(Icheckbound, _) -> 2
| Ifloatofint -> 10
| Iintoffloat -> 10
| _ -> 1
(* Say that reloadgp is not part of a basic block (prevents moving it
past an operation that uses $gp) *)
method oper_in_basic_block = function
Ispecific(Ireloadgp _) -> false
| op -> super#oper_in_basic_block op
end
let fundecl =
if Arch.digital_asm
then (fun f -> f)
else (new scheduler ())#fundecl