Merge of the nonstrict-ops branch:

- Most RTL operators now evaluate to Some Vundef instead of None
  when undefined behavior occurs.
- More aggressive instruction selection.
- "Bertotization" of pattern-matchings now implemented by a proper preprocessor.
- Cast optimization moved to cfrontend/Cminorgen; removed backend/CastOptim.


git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1790 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e

1 files changed, 416 insertions, 0 deletions

diff --git a/ia32/SelectOp.vp b/ia32/SelectOp.vp
new file mode 100644
index 0000000..71dc83b
--- /dev/null
+++ b/ia32/SelectOp.vp
@@ -0,0 +1,416 @@
+(* *********************************************************************)
+(*                                                                     *)
+(*              The Compcert verified compiler                         *)
+(*                                                                     *)
+(*          Xavier Leroy, INRIA Paris-Rocquencourt                     *)
+(*                                                                     *)
+(*  Copyright Institut National de Recherche en Informatique et en     *)
+(*  Automatique.  All rights reserved.  This file is distributed       *)
+(*  under the terms of the INRIA Non-Commercial License Agreement.     *)
+(*                                                                     *)
+(* *********************************************************************)
+
+(** Instruction selection for operators *)
+
+(** The instruction selection pass recognizes opportunities for using
+  combined arithmetic and logical operations and addressing modes
+  offered by the target processor.  For instance, the expression [x + 1]
+  can take advantage of the "immediate add" instruction of the processor,
+  and on the PowerPC, the expression [(x >> 6) & 0xFF] can be turned
+  into a "rotate and mask" instruction.
+
+  This file defines functions for building CminorSel expressions and
+  statements, especially expressions consisting of operator
+  applications.  These functions examine their arguments to choose
+  cheaper forms of operators whenever possible.
+
+  For instance, [add e1 e2] will return a CminorSel expression semantically
+  equivalent to [Eop Oadd (e1 ::: e2 ::: Enil)], but will use a
+  [Oaddimm] operator if one of the arguments is an integer constant,
+  or suppress the addition altogether if one of the arguments is the
+  null integer.  In passing, we perform operator reassociation
+  ([(e + c1) * c2] becomes [(e * c2) + (c1 * c2)]) and a small amount
+  of constant propagation.
+
+  On top of the "smart constructor" functions defined below,
+  module [Selection] implements the actual instruction selection pass.
+*)
+
+Require Import Coqlib.
+Require Import Maps.
+Require Import AST.
+Require Import Integers.
+Require Import Floats.
+Require Import Values.
+Require Import Memory.
+Require Import Globalenvs.
+Require Cminor.
+Require Import Op.
+Require Import CminorSel.
+
+Open Local Scope cminorsel_scope.
+
+(** ** Constants **)
+
+Definition addrsymbol (id: ident) (ofs: int) :=
+  Eop (Olea (Aglobal id ofs)) Enil.
+
+Definition addrstack (ofs: int) :=
+  Eop (Olea (Ainstack ofs)) Enil.
+
+(** ** Integer logical negation *)
+
+Definition notint (e: expr) := Eop (Oxorimm Int.mone) (e ::: Enil).
+
+(** ** Boolean negation *)
+
+Fixpoint notbool (e: expr) {struct e} : expr :=
+  let default := Eop (Ocmp (Ccompuimm Ceq Int.zero)) (e ::: Enil) in
+  match e with 
+  | Eop (Ointconst n) Enil =>
+      Eop (Ointconst (if Int.eq n Int.zero then Int.one else Int.zero)) Enil
+  | Eop (Ocmp cond) args =>
+      Eop (Ocmp (negate_condition cond)) args
+  | Econdition e1 e2 e3 =>
+      Econdition e1 (notbool e2) (notbool e3)
+  | _ =>
+      default
+  end.
+
+(** ** Integer addition and pointer addition *)
+
+Definition offset_addressing (a: addressing) (ofs: int) : addressing :=
+  match a with
+  | Aindexed n => Aindexed (Int.add n ofs)
+  | Aindexed2 n => Aindexed2 (Int.add n ofs)
+  | Ascaled sc n => Ascaled sc (Int.add n ofs)
+  | Aindexed2scaled sc n => Aindexed2scaled sc (Int.add n ofs)
+  | Aglobal id n => Aglobal id (Int.add n ofs)
+  | Abased id n => Abased id (Int.add n ofs)
+  | Abasedscaled sc id n => Abasedscaled sc id (Int.add n ofs)
+  | Ainstack n => Ainstack (Int.add n ofs)
+  end.
+
+Nondetfunction addimm (n: int) (e: expr) :=
+  if Int.eq n Int.zero then e else
+  match e with
+  | Eop (Ointconst m) Enil       => Eop (Ointconst(Int.add n m)) Enil
+  | Eop (Olea addr) args         => Eop (Olea (offset_addressing addr n)) args
+  | _                            => Eop (Olea (Aindexed n)) (e ::: Enil)
+  end.
+
+Nondetfunction add (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | Eop (Ointconst n1) Enil, t2 => addimm n1 t2
+  | t1, Eop (Ointconst n2) Enil => addimm n2 t1
+  | Eop (Olea (Aindexed n1)) (t1:::Enil), Eop (Olea (Aindexed n2)) (t2:::Enil) =>
+      Eop (Olea (Aindexed2 (Int.add n1 n2))) (t1:::t2:::Enil)
+  | Eop (Olea (Aindexed n1)) (t1:::Enil), Eop (Olea (Ascaled sc n2)) (t2:::Enil) =>
+      Eop (Olea (Aindexed2scaled sc (Int.add n1 n2))) (t1:::t2:::Enil)
+  | Eop (Olea (Ascaled sc n1)) (t1:::Enil), Eop (Olea (Aindexed n2)) (t2:::Enil) =>
+      Eop (Olea (Aindexed2scaled sc (Int.add n1 n2))) (t2:::t1:::Enil)
+  | Eop (Olea (Aindexed n1)) (t1:::Enil), Eop (Olea (Aglobal id ofs)) Enil =>
+      Eop (Olea (Abased id (Int.add ofs n1))) (t1:::Enil)
+  | Eop (Olea (Aglobal id ofs)) Enil, Eop (Olea (Aindexed n2)) (t2:::Enil) =>
+      Eop (Olea (Abased id (Int.add ofs n2))) (t2:::Enil)
+  | Eop (Olea (Ascaled sc n1)) (t1:::Enil), Eop (Olea (Aglobal id ofs)) Enil =>
+      Eop (Olea (Abasedscaled sc id (Int.add ofs n1))) (t1:::Enil)
+  | Eop (Olea (Aglobal id ofs)) Enil, Eop (Olea (Ascaled sc n2)) (t2:::Enil) =>
+      Eop (Olea (Abasedscaled sc id (Int.add ofs n2))) (t2:::Enil)
+  | Eop (Olea (Ascaled sc n)) (t1:::Enil), t2 =>
+      Eop (Olea (Aindexed2scaled sc n)) (t2:::t1:::Enil)
+  | t1, Eop (Olea (Ascaled sc n)) (t2:::Enil) =>
+      Eop (Olea (Aindexed2scaled sc n)) (t1:::t2:::Enil)
+  | Eop (Olea (Aindexed n)) (t1:::Enil), t2 =>
+      Eop (Olea (Aindexed2 n)) (t1:::t2:::Enil)
+  | t1, Eop (Olea (Aindexed n)) (t2:::Enil) =>
+      Eop (Olea (Aindexed2 n)) (t1:::t2:::Enil)
+  | _, _ =>
+      Eop (Olea (Aindexed2 Int.zero)) (e1:::e2:::Enil)
+  end.
+
+(** ** Integer and pointer subtraction *)
+
+Nondetfunction sub (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | t1, Eop (Ointconst n2) Enil => addimm (Int.neg n2) t1
+  | Eop (Olea (Aindexed n1)) (t1:::Enil), Eop (Olea (Aindexed n2)) (t2:::Enil) =>
+      addimm (Int.sub n1 n2) (Eop Osub (t1:::t2:::Enil))
+  | Eop (Olea (Aindexed n1)) (t1:::Enil), t2 =>
+      addimm n1 (Eop Osub (t1:::t2:::Enil))
+  | t1, Eop (Olea (Aindexed n2)) (t2:::Enil) =>
+      addimm (Int.neg n2) (Eop Osub (t1:::t2:::Enil))
+  | _, _ =>
+      Eop Osub (e1:::e2:::Enil)
+  end.
+
+Definition negint (e: expr) := Eop Oneg (e ::: Enil).
+
+(** ** Immediate shifts *)
+
+Definition shift_is_scale (n: int) : bool :=
+  Int.eq n (Int.repr 1) || Int.eq n (Int.repr 2) || Int.eq n (Int.repr 3).
+
+Nondetfunction shlimm (e1: expr) (n: int) :=
+  if Int.eq n Int.zero then e1 else
+  match e1 with
+  | Eop (Ointconst n1) Enil =>
+      Eop (Ointconst(Int.shl n1 n)) Enil
+  | Eop (Oshlimm n1) (t1:::Enil) =>
+      if Int.ltu (Int.add n n1) Int.iwordsize
+      then Eop (Oshlimm (Int.add n n1)) (t1:::Enil)
+      else Eop (Oshlimm n) (e1:::Enil)
+  | Eop (Olea (Aindexed n1)) (t1:::Enil) =>
+      if shift_is_scale n
+      then Eop (Olea (Ascaled (Int.shl Int.one n) (Int.shl n1 n))) (t1:::Enil)
+      else Eop (Oshlimm n) (e1:::Enil)
+  | _ =>
+      if shift_is_scale n
+      then Eop (Olea (Ascaled (Int.shl Int.one n) Int.zero)) (e1:::Enil)
+      else Eop (Oshlimm n) (e1:::Enil)
+  end.
+
+Nondetfunction shruimm (e1: expr) (n: int) :=
+  if Int.eq n Int.zero then e1 else
+  match e1 with
+  | Eop (Ointconst n1) Enil =>
+      Eop (Ointconst(Int.shru n1 n)) Enil
+  | Eop (Oshruimm n1) (t1:::Enil) =>
+      if Int.ltu (Int.add n n1) Int.iwordsize
+      then Eop (Oshruimm (Int.add n n1)) (t1:::Enil)
+      else Eop (Oshruimm n) (e1:::Enil)
+  | _ =>
+      Eop (Oshruimm n) (e1:::Enil)
+  end.
+
+Nondetfunction shrimm (e1: expr) (n: int) :=
+  if Int.eq n Int.zero then e1 else
+  match e1 with
+  | Eop (Ointconst n1) Enil =>
+      Eop (Ointconst(Int.shr n1 n)) Enil
+  | Eop (Oshrimm n1) (t1:::Enil) =>
+      if Int.ltu (Int.add n n1) Int.iwordsize
+      then Eop (Oshrimm (Int.add n n1)) (t1:::Enil)
+      else Eop (Oshrimm n) (e1:::Enil)
+  | _ =>
+      Eop (Oshrimm n) (e1:::Enil)
+  end.
+
+(** ** Integer multiply *)
+
+Definition mulimm_base (n1: int) (e2: expr) :=
+  match Int.one_bits n1 with
+  | i :: nil =>
+      shlimm e2 i
+  | i :: j :: nil =>
+      Elet e2 (add (shlimm (Eletvar 0) i) (shlimm (Eletvar 0) j))
+  | _ =>
+      Eop (Omulimm n1) (e2:::Enil)
+  end.
+
+Nondetfunction mulimm (n1: int) (e2: expr) :=
+  if Int.eq n1 Int.zero then Eop (Ointconst Int.zero) Enil
+  else if Int.eq n1 Int.one then e2
+  else match e2 with
+  | Eop (Ointconst n2) Enil => Eop (Ointconst(Int.mul n1 n2)) Enil
+  | Eop (Olea (Aindexed n2)) (t2:::Enil) => addimm (Int.mul n1 n2) (mulimm_base n1 t2)
+  | _ => mulimm_base n1 e2
+  end.
+
+Nondetfunction mul (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | Eop (Ointconst n1) Enil, t2 => mulimm n1 t2
+  | t1, Eop (Ointconst n2) Enil => mulimm n2 t1
+  | _, _ => Eop Omul (e1:::e2:::Enil)
+  end.
+
+(** ** Bitwise and, or, xor *)
+
+Nondetfunction andimm (n1: int) (e2: expr) :=
+  if Int.eq n1 Int.zero then Eop (Ointconst Int.zero) Enil
+  else if Int.eq n1 Int.mone then e2
+  else match e2 with
+  | Eop (Ointconst n2) Enil =>
+      Eop (Ointconst (Int.and n1 n2)) Enil
+  | Eop (Oandimm n2) (t2:::Enil) =>
+     Eop (Oandimm (Int.and n1 n2)) (t2:::Enil)
+  | Eop Ocast8unsigned (t2:::Enil) =>
+     Eop (Oandimm (Int.and n1 (Int.repr 255))) (t2:::Enil)
+  | Eop Ocast16unsigned (t2:::Enil) =>
+     Eop (Oandimm (Int.and n1 (Int.repr 65535))) (t2:::Enil)
+  | _ =>
+     Eop (Oandimm n1) (e2:::Enil)
+  end.
+
+Nondetfunction and (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | Eop (Ointconst n1) Enil, t2 => andimm n1 t2
+  | t1, Eop (Ointconst n2) Enil => andimm n2 t1
+  | _, _ => Eop Oand (e1:::e2:::Enil)
+  end.
+
+Nondetfunction orimm (n1: int) (e2: expr) :=
+  if Int.eq n1 Int.zero then e2
+  else if Int.eq n1 Int.mone then Eop (Ointconst Int.mone) Enil
+  else match e2 with
+  | Eop (Ointconst n2) Enil =>
+      Eop (Ointconst (Int.or n1 n2)) Enil
+  | Eop (Oorimm n2) (t2:::Enil) =>
+     Eop (Oorimm (Int.or n1 n2)) (t2:::Enil)
+  | _ =>
+     Eop (Oorimm n1) (e2:::Enil)
+  end.
+
+Definition same_expr_pure (e1 e2: expr) :=
+  match e1, e2 with
+  | Evar v1, Evar v2 => if ident_eq v1 v2 then true else false
+  | _, _ => false
+  end.
+
+Nondetfunction or (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | Eop (Ointconst n1) Enil, t2 => orimm n1 t2
+  | t1, Eop (Ointconst n2) Enil => orimm n2 t1
+  | Eop (Oshlimm n1) (t1:::Enil), Eop (Oshruimm n2) (t2:::Enil) =>
+      if Int.eq (Int.add n1 n2) Int.iwordsize
+      && same_expr_pure t1 t2
+      then Eop (Ororimm n2) (t1:::Enil)
+      else Eop Oor (e1:::e2:::Enil)
+  | Eop (Oshruimm n2) (t2:::Enil), Eop (Oshlimm n1) (t1:::Enil) =>
+      if Int.eq (Int.add n1 n2) Int.iwordsize
+      && same_expr_pure t1 t2
+      then Eop (Ororimm n2) (t1:::Enil)
+      else Eop Oor (e1:::e2:::Enil)
+  | _, _ =>
+      Eop Oor (e1:::e2:::Enil)
+  end.
+
+Nondetfunction xorimm (n1: int) (e2: expr) :=
+  if Int.eq n1 Int.zero then e2
+  else match e2 with
+  | Eop (Ointconst n2) Enil =>
+      Eop (Ointconst (Int.xor n1 n2)) Enil
+  | Eop (Oxorimm n2) (t2:::Enil) =>
+     Eop (Oxorimm (Int.xor n1 n2)) (t2:::Enil)
+  | _ =>
+     Eop (Oxorimm n1) (e2:::Enil)
+  end.
+
+Nondetfunction xor (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | Eop (Ointconst n1) Enil, t2 => xorimm n1 t2
+  | t1, Eop (Ointconst n2) Enil => xorimm n2 t1
+  | _, _ => Eop Oxor (e1:::e2:::Enil)
+  end.
+
+(** ** Integer division and modulus *)
+
+Definition divu (e1: expr) (e2: expr) := Eop Odivu (e1:::e2:::Enil).
+Definition modu (e1: expr) (e2: expr) := Eop Omodu (e1:::e2:::Enil).
+Definition divs (e1: expr) (e2: expr) := Eop Odiv (e1:::e2:::Enil).
+Definition mods (e1: expr) (e2: expr) := Eop Omod (e1:::e2:::Enil).
+
+(** ** General shifts *)
+
+Nondetfunction shl (e1: expr) (e2: expr) :=
+  match e2 with
+  | Eop (Ointconst n2) Enil => shlimm e1 n2
+  | _ => Eop Oshl (e1:::e2:::Enil)
+  end.
+
+Nondetfunction shr (e1: expr) (e2: expr) :=
+  match e2 with
+  | Eop (Ointconst n2) Enil => shrimm e1 n2
+  | _ => Eop Oshr (e1:::e2:::Enil)
+  end.
+
+Nondetfunction shru (e1: expr) (e2: expr) :=
+  match e2 with
+  | Eop (Ointconst n2) Enil => shruimm e1 n2
+  | _ => Eop Oshru (e1:::e2:::Enil)
+  end.
+
+(** ** Floating-point arithmetic *)
+
+Definition negf (e: expr) :=  Eop Onegf (e ::: Enil).
+Definition absf (e: expr) :=  Eop Oabsf (e ::: Enil).
+Definition addf (e1 e2: expr) :=  Eop Oaddf (e1 ::: e2 ::: Enil).
+Definition subf (e1 e2: expr) :=  Eop Osubf (e1 ::: e2 ::: Enil).
+Definition mulf (e1 e2: expr) :=  Eop Omulf (e1 ::: e2 ::: Enil).
+Definition divf (e1 e2: expr) :=  Eop Odivf (e1 ::: e2 ::: Enil).
+
+(** ** Comparisons *)
+
+Nondetfunction comp (c: comparison) (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | Eop (Ointconst n1) Enil, t2 =>
+      Eop (Ocmp (Ccompimm (swap_comparison c) n1)) (t2 ::: Enil)
+  | t1, Eop (Ointconst n2) Enil =>
+      Eop (Ocmp (Ccompimm c n2)) (t1 ::: Enil)
+  | _, _ =>
+      Eop (Ocmp (Ccomp c)) (e1 ::: e2 ::: Enil)
+  end.
+
+Nondetfunction compu (c: comparison) (e1: expr) (e2: expr) :=
+  match e1, e2 with
+  | Eop (Ointconst n1) Enil, t2 =>
+      Eop (Ocmp (Ccompuimm (swap_comparison c) n1)) (t2 ::: Enil)
+  | t1, Eop (Ointconst n2) Enil =>
+      Eop (Ocmp (Ccompuimm c n2)) (t1 ::: Enil)
+  | _, _ =>
+      Eop (Ocmp (Ccompu c)) (e1 ::: e2 ::: Enil)
+  end.
+
+Definition compf (c: comparison) (e1: expr) (e2: expr) :=
+  Eop (Ocmp (Ccompf c)) (e1 ::: e2 ::: Enil).
+
+(** ** Integer conversions *)
+
+Nondetfunction cast8unsigned (e: expr) := 
+  match e with
+  | Eop (Oandimm n) (t:::Enil) =>
+      Eop (Oandimm (Int.and (Int.repr 255) n)) (t:::Enil)
+  | _ =>
+      Eop Ocast8unsigned (e:::Enil)
+  end.
+
+Definition cast8signed (e: expr) := Eop Ocast8signed (e ::: Enil).
+
+Nondetfunction cast16unsigned (e: expr) := 
+  match e with
+  | Eop (Oandimm n) (t:::Enil) =>
+      Eop (Oandimm (Int.and (Int.repr 65535) n)) (t:::Enil)
+  | _ =>
+      Eop Ocast16unsigned (e:::Enil)
+  end.
+
+Definition cast16signed (e: expr) := Eop Ocast16signed (e ::: Enil).
+
+(** Floating-point conversions *)
+
+Definition singleoffloat (e: expr) := Eop Osingleoffloat (e ::: Enil).
+Definition intoffloat (e: expr) := Eop Ointoffloat (e ::: Enil).
+Definition floatofint (e: expr) := Eop Ofloatofint (e ::: Enil).
+
+Definition intuoffloat (e: expr) :=
+  let f := Eop (Ofloatconst (Float.floatofintu Float.ox8000_0000)) Enil in
+  Elet e
+    (Econdition (CEcond (Ccompf Clt) (Eletvar O ::: f ::: Enil))
+      (intoffloat (Eletvar O))
+      (addimm Float.ox8000_0000 (intoffloat (subf (Eletvar O) f)))).
+
+Definition floatofintu (e: expr) :=
+  let f := Eop (Ofloatconst (Float.floatofintu Float.ox8000_0000)) Enil in
+  Elet e
+    (Econdition (CEcond (Ccompuimm Clt Float.ox8000_0000) (Eletvar O ::: Enil))
+      (floatofint (Eletvar O))
+      (addf (floatofint (addimm (Int.neg Float.ox8000_0000) (Eletvar O))) f)).
+
+(** ** Addressing modes *)
+
+Nondetfunction addressing (chunk: memory_chunk) (e: expr) :=
+  match e with
+  | Eop (Olea addr) args => (addr, args)
+  | _ => (Aindexed Int.zero, e:::Enil)
+  end.
+