RISC-V port and assorted changes

This commits adds code generation for the RISC-V architecture, both in 32- and 64-bit modes.

The generated code was lightly tested using the simulator and cross-binutils from https://riscv.org/software-tools/

This port required the following additional changes:

- Integers: More properties about shrx

- SelectOp: now provides smart constructors for mulhs and mulhu

- SelectDiv, 32-bit integer division and modulus: implement constant propagation, use the new smart constructors mulhs and mulhu.

- Runtime library: if no asm implementation is provided, run the reference C implementation through CompCert.  Since CompCert rejects the definitions of names of special functions such as __i64_shl, the reference implementation now uses "i64_" names, e.g. "i64_shl", and a renaming "i64_ -> __i64_" is performed over the generated assembly file, before assembling and building the runtime library.

- test/: add SIMU make variable to run tests through a simulator

- test/regression/alignas.c: make sure _Alignas and _Alignof are not #define'd by C headers

commit da14495c01cf4f66a928c2feff5c53f09bde837f
Author: Xavier Leroy <xavier.leroy@inria.fr>
Date:   Thu Apr 13 17:36:10 2017 +0200

    RISC-V port, continued

    Now working on Asmgen.

commit 36f36eb3a5abfbb8805960443d087b6a83e86005
Author: Xavier Leroy <xavier.leroy@inria.fr>
Date:   Wed Apr 12 17:26:39 2017 +0200

    RISC-V port, first steps

    This port is based on Prashanth Mundkur's experimental RV32 port and brings it up to date with CompCert, and adds 64-bit support (RV64).  Work in progress.

1 files changed, 364 insertions, 0 deletions

diff --git a/riscV/SelectLong.vp b/riscV/SelectLong.vp
new file mode 100644
index 00000000..b3e07bf5
--- /dev/null
+++ b/riscV/SelectLong.vp
@@ -0,0 +1,364 @@
+(* *********************************************************************)
+(*                                                                     *)
+(*              The Compcert verified compiler                         *)
+(*                                                                     *)
+(*                 Xavier Leroy, INRIA Paris                           *)
+(*           Prashanth Mundkur, SRI International                      *)
+(*                                                                     *)
+(*  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.     *)
+(*                                                                     *)
+(*  The contributions by Prashanth Mundkur are reused and adapted      *)
+(*  under the terms of a Contributor License Agreement between         *)
+(*  SRI International and INRIA.                                       *)
+(*                                                                     *)
+(* *********************************************************************)
+
+(** Instruction selection for 64-bit integer operations *)
+
+Require Import Coqlib.
+Require Import Compopts.
+Require Import AST Integers Floats.
+Require Import Op CminorSel.
+Require Import SelectOp SplitLong.
+
+Local Open Scope cminorsel_scope.
+Local Open Scope string_scope.
+
+Section SELECT.
+
+Context {hf: helper_functions}.
+
+Definition longconst (n: int64) : expr :=
+  if Archi.splitlong then SplitLong.longconst n else Eop (Olongconst n) Enil.
+
+Definition is_longconst (e: expr) :=
+  if Archi.splitlong then SplitLong.is_longconst e else
+  match e with
+  | Eop (Olongconst n) Enil => Some n
+  | _ => None
+  end.
+
+Definition intoflong (e: expr) :=
+  if Archi.splitlong then SplitLong.intoflong e else
+  match is_longconst e with
+  | Some n => Eop (Ointconst (Int.repr (Int64.unsigned n))) Enil
+  | None =>  Eop Olowlong (e ::: Enil)
+  end.
+
+Definition longofint (e: expr) :=
+  if Archi.splitlong then SplitLong.longofint e else
+  match is_intconst e with
+  | Some n => longconst (Int64.repr (Int.signed n))
+  | None =>  Eop Ocast32signed (e ::: Enil)
+  end.
+
+Definition longofintu (e: expr) :=
+  if Archi.splitlong then SplitLong.longofintu e else
+  match is_intconst e with
+  | Some n => longconst (Int64.repr (Int.unsigned n))
+  | None =>  Eop Ocast32unsigned (e ::: Enil)
+  end.
+
+(** ** Integer addition and pointer addition *)
+
+Nondetfunction addlimm (n: int64) (e: expr) :=
+  if Int64.eq n Int64.zero then e else
+  match e with
+  | Eop (Olongconst m) Enil => longconst (Int64.add n m)
+  | Eop (Oaddrsymbol s m) Enil   => Eop (Oaddrsymbol s (Ptrofs.add (Ptrofs.of_int64 n) m)) Enil
+  | Eop (Oaddrstack m) Enil      => Eop (Oaddrstack (Ptrofs.add (Ptrofs.of_int64 n) m)) Enil
+  | Eop (Oaddlimm m) (t ::: Enil) => Eop (Oaddlimm(Int64.add n m)) (t ::: Enil)
+  | _ => Eop (Oaddlimm n) (e ::: Enil)
+  end.
+
+Nondetfunction addl (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.addl e1 e2 else
+  match e1, e2 with
+  | Eop (Olongconst n1) Enil, t2 => addlimm n1 t2
+  | t1, Eop (Olongconst n2) Enil => addlimm n2 t1
+  | Eop (Oaddlimm n1) (t1:::Enil), Eop (Oaddlimm n2) (t2:::Enil) =>
+      addlimm (Int64.add n1 n2) (Eop Oaddl (t1:::t2:::Enil))
+  | Eop (Oaddlimm n1) (t1:::Enil), Eop (Oaddrstack n2) Enil =>
+      Eop Oaddl (Eop (Oaddrstack (Ptrofs.add (Ptrofs.of_int64 n1) n2)) Enil ::: t1 ::: Enil)
+  | Eop (Oaddrstack n1) Enil, Eop (Oaddlimm n2) (t2:::Enil) =>
+      Eop Oaddl (Eop (Oaddrstack (Ptrofs.add n1 (Ptrofs.of_int64 n2))) Enil ::: t2 ::: Enil)
+  | Eop (Oaddlimm n1) (t1:::Enil), t2 =>
+      addlimm n1 (Eop Oaddl (t1:::t2:::Enil))
+  | t1, Eop (Oaddlimm n2) (t2:::Enil) =>
+      addlimm n2 (Eop Oaddl (t1:::t2:::Enil))
+  | _, _ => Eop Oaddl (e1:::e2:::Enil)
+  end.
+
+(** ** Integer and pointer subtraction *)
+
+Nondetfunction subl (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.subl e1 e2 else
+  match e1, e2 with
+  | t1, Eop (Olongconst n2) Enil =>
+      addlimm (Int64.neg n2) t1
+  | Eop (Oaddlimm n1) (t1:::Enil), Eop (Oaddlimm n2) (t2:::Enil) =>
+      addlimm (Int64.sub n1 n2) (Eop Osubl (t1:::t2:::Enil))
+  | Eop (Oaddlimm n1) (t1:::Enil), t2 =>
+      addlimm n1 (Eop Osubl (t1:::t2:::Enil))
+  | t1, Eop (Oaddlimm n2) (t2:::Enil) =>
+      addlimm (Int64.neg n2) (Eop Osubl (t1:::t2:::Enil))
+  | _, _ => Eop Osubl (e1:::e2:::Enil)
+  end.
+
+Definition negl (e: expr) :=
+  if Archi.splitlong then SplitLong.negl e else
+  match is_longconst e with
+  | Some n => longconst (Int64.neg n)
+  | None =>  Eop Onegl (e ::: Enil)
+  end.
+
+(** ** Immediate shifts *)
+
+Nondetfunction shllimm (e1: expr) (n: int) :=
+  if Archi.splitlong then SplitLong.shllimm e1 n else
+  if Int.eq n Int.zero then
+    e1
+  else if negb (Int.ltu n Int64.iwordsize') then
+    Eop Oshll (e1 ::: Eop (Ointconst n) Enil ::: Enil)
+  else match e1 with
+    | Eop (Olongconst n1) Enil =>
+        longconst (Int64.shl' n1 n)
+    | Eop (Oshllimm n1) (t1:::Enil) =>
+        if Int.ltu (Int.add n n1) Int64.iwordsize'
+        then Eop (Oshllimm (Int.add n n1)) (t1:::Enil)
+        else Eop (Oshllimm n) (e1:::Enil)
+    | _ =>
+        Eop (Oshllimm n) (e1:::Enil)
+  end.
+
+Nondetfunction shrluimm (e1: expr) (n: int) :=
+  if Archi.splitlong then SplitLong.shrluimm e1 n else
+  if Int.eq n Int.zero then e1 else
+  if negb (Int.ltu n Int64.iwordsize') then
+    Eop Oshrlu (e1:::Eop (Ointconst n) Enil:::Enil)
+  else
+    match e1 with
+    | Eop (Olongconst n1) Enil =>
+        longconst (Int64.shru' n1 n)
+    | Eop (Oshrluimm n1) (t1:::Enil) =>
+        if Int.ltu (Int.add n n1) Int64.iwordsize'
+        then Eop (Oshrluimm (Int.add n n1)) (t1:::Enil)
+        else Eop (Oshrluimm n) (e1:::Enil)
+    | _ =>
+        Eop (Oshrluimm n) (e1:::Enil)
+    end.
+
+Nondetfunction shrlimm (e1: expr) (n: int) :=
+  if Archi.splitlong then SplitLong.shrlimm e1 n else
+  if Int.eq n Int.zero then e1 else
+  if negb (Int.ltu n Int64.iwordsize') then
+    Eop Oshrl (e1:::Eop (Ointconst n) Enil:::Enil)
+  else
+  match e1 with
+  | Eop (Olongconst n1) Enil =>
+      longconst (Int64.shr' n1 n)
+  | Eop (Oshrlimm n1) (t1:::Enil) =>
+      if Int.ltu (Int.add n n1) Int64.iwordsize'
+      then Eop (Oshrlimm (Int.add n n1)) (t1:::Enil)
+      else Eop (Oshrlimm n) (e1:::Enil)
+  | _ =>
+      Eop (Oshrlimm n) (e1:::Enil)
+  end.
+
+(** ** General shifts *)
+
+Definition shll (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.shll e1 e2 else
+  match is_intconst e2 with
+  | Some n2 => shllimm e1 n2
+  | None => Eop Oshll (e1:::e2:::Enil)
+  end.
+
+Definition shrl (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.shrl e1 e2 else
+  match is_intconst e2 with
+  | Some n2 => shrlimm e1 n2
+  | None => Eop Oshrl (e1:::e2:::Enil)
+  end.
+
+Definition shrlu (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.shrlu e1 e2 else
+  match is_intconst e2 with
+  | Some n2 => shrluimm e1 n2
+  | _ => Eop Oshrlu (e1:::e2:::Enil)
+  end.
+
+(** ** Integer multiply *)
+
+Definition mullimm_base (n1: int64) (e2: expr) :=
+  match Int64.one_bits' n1 with
+  | i :: nil =>
+      shllimm e2 i
+  | i :: j :: nil =>
+      Elet e2 (addl (shllimm (Eletvar 0) i) (shllimm (Eletvar 0) j))
+  | _ =>
+      Eop Omull (e2 ::: longconst n1 ::: Enil)
+  end.
+
+Nondetfunction mullimm (n1: int64) (e2: expr) :=
+  if Archi.splitlong then SplitLong.mullimm n1 e2
+  else if Int64.eq n1 Int64.zero then longconst Int64.zero
+  else if Int64.eq n1 Int64.one then e2
+  else match e2 with
+  | Eop (Olongconst n2) Enil => longconst (Int64.mul n1 n2)
+  | Eop (Oaddlimm n2) (t2:::Enil) => addlimm (Int64.mul n1 n2) (mullimm_base n1 t2)
+  | _ => mullimm_base n1 e2
+  end.
+
+Nondetfunction mull (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.mull e1 e2 else
+  match e1, e2 with
+  | Eop (Olongconst n1) Enil, t2 => mullimm n1 t2
+  | t1, Eop (Olongconst n2) Enil => mullimm n2 t1
+  | _, _ => Eop Omull (e1:::e2:::Enil)
+  end.
+
+Definition mullhu (e1: expr) (n2: int64) :=
+  if Archi.splitlong then SplitLong.mullhu e1 n2 else
+  Eop Omullhu (e1 ::: longconst n2 ::: Enil).
+
+Definition mullhs (e1: expr) (n2: int64) :=
+  if Archi.splitlong then SplitLong.mullhs e1 n2 else
+  Eop Omullhs (e1 ::: longconst n2 ::: Enil).
+
+(** ** Bitwise and, or, xor *)
+
+Nondetfunction andlimm (n1: int64) (e2: expr) := 
+  if Int64.eq n1 Int64.zero then longconst Int64.zero else
+  if Int64.eq n1 Int64.mone then e2 else
+  match e2 with
+  | Eop (Olongconst n2) Enil =>
+      longconst (Int64.and n1 n2)
+  | Eop (Oandlimm n2) (t2:::Enil) =>
+      Eop (Oandlimm (Int64.and n1 n2)) (t2:::Enil)
+  | _ =>
+      Eop (Oandlimm n1) (e2:::Enil)
+  end.
+
+Nondetfunction andl (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.andl e1 e2 else
+  match e1, e2 with
+  | Eop (Olongconst n1) Enil, t2 => andlimm n1 t2
+  | t1, Eop (Olongconst n2) Enil => andlimm n2 t1
+  | _, _ => Eop Oandl (e1:::e2:::Enil)
+  end.
+
+Nondetfunction orlimm (n1: int64) (e2: expr) :=
+  if Int64.eq n1 Int64.zero then e2 else
+  if Int64.eq n1 Int64.mone then longconst Int64.mone else
+  match e2 with
+  | Eop (Olongconst n2) Enil => longconst (Int64.or n1 n2)
+  | Eop (Oorlimm n2) (t2:::Enil) => Eop (Oorlimm (Int64.or n1 n2)) (t2:::Enil)
+  | _ => Eop (Oorlimm n1) (e2:::Enil)
+  end.
+
+Nondetfunction orl (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.orl e1 e2 else
+  match e1, e2 with
+  | Eop (Olongconst n1) Enil, t2 => orlimm n1 t2
+  | t1, Eop (Olongconst n2) Enil => orlimm n2 t1
+  | _, _ => Eop Oorl (e1:::e2:::Enil)
+  end.
+
+Nondetfunction xorlimm (n1: int64) (e2: expr) :=
+  if Int64.eq n1 Int64.zero then e2 else
+  match e2 with
+  | Eop (Olongconst n2) Enil => longconst (Int64.xor n1 n2)
+  | Eop (Oxorlimm n2) (t2:::Enil) =>
+      let n := Int64.xor n1 n2 in
+      if Int64.eq n Int64.zero then t2 else Eop (Oxorlimm n) (t2:::Enil)
+  | _ => Eop (Oxorlimm n1) (e2:::Enil)
+  end.
+
+Nondetfunction xorl (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.xorl e1 e2 else
+  match e1, e2 with
+  | Eop (Olongconst n1) Enil, t2 => xorlimm n1 t2
+  | t1, Eop (Olongconst n2) Enil => xorlimm n2 t1
+  | _, _ => Eop Oxorl (e1:::e2:::Enil)
+  end.
+
+(** ** Integer logical negation *)
+
+Definition notl (e: expr) :=
+  if Archi.splitlong then SplitLong.notl e else xorlimm Int64.mone e.
+
+(** ** Integer division and modulus *)
+
+Definition divlu_base (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.divlu_base e1 e2 else Eop Odivlu (e1:::e2:::Enil).
+Definition modlu_base (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.modlu_base e1 e2 else Eop Omodlu (e1:::e2:::Enil).
+Definition divls_base (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.divls_base e1 e2 else Eop Odivl (e1:::e2:::Enil).
+Definition modls_base (e1: expr) (e2: expr) :=
+  if Archi.splitlong then SplitLong.modls_base e1 e2 else Eop Omodl (e1:::e2:::Enil).
+
+Definition shrxlimm (e: expr) (n: int) :=
+  if Archi.splitlong then SplitLong.shrxlimm e n else
+  if Int.eq n Int.zero then e else Eop (Oshrxlimm n) (e ::: Enil).
+
+(** ** Comparisons *)
+
+Definition cmplu (c: comparison) (e1 e2: expr) :=
+  if Archi.splitlong then SplitLong.cmplu c e1 e2 else
+  match is_longconst e1, is_longconst e2 with
+  | Some n1, Some n2 =>
+      Eop (Ointconst (if Int64.cmpu c n1 n2 then Int.one else Int.zero)) Enil
+  | Some n1, None => Eop (Ocmp (Ccompluimm (swap_comparison c) n1)) (e2:::Enil)
+  | None, Some n2 => Eop (Ocmp (Ccompluimm c n2)) (e1:::Enil)
+  | None, None => Eop (Ocmp (Ccomplu c)) (e1:::e2:::Enil)
+  end.
+
+Definition cmpl (c: comparison) (e1 e2: expr) :=
+  if Archi.splitlong then SplitLong.cmpl c e1 e2 else
+  match is_longconst e1, is_longconst e2 with
+  | Some n1, Some n2 =>
+      Eop (Ointconst (if Int64.cmp c n1 n2 then Int.one else Int.zero)) Enil
+  | Some n1, None => Eop (Ocmp (Ccomplimm (swap_comparison c) n1)) (e2:::Enil)
+  | None, Some n2 => Eop (Ocmp (Ccomplimm c n2)) (e1:::Enil)
+  | None, None => Eop (Ocmp (Ccompl c)) (e1:::e2:::Enil)
+  end.
+
+(** ** Floating-point conversions *)
+
+Definition longoffloat (e: expr) :=
+  if Archi.splitlong then SplitLong.longoffloat e else 
+  Eop Olongoffloat (e:::Enil).
+
+Definition longuoffloat (e: expr) :=
+  if Archi.splitlong then SplitLong.longuoffloat e else 
+  Eop Olonguoffloat (e:::Enil).
+
+Definition floatoflong (e: expr) := 
+  if Archi.splitlong then SplitLong.floatoflong e else 
+  Eop Ofloatoflong (e:::Enil).
+
+Definition floatoflongu (e: expr) := 
+  if Archi.splitlong then SplitLong.floatoflongu e else 
+  Eop Ofloatoflongu (e:::Enil).
+
+Definition longofsingle (e: expr) := 
+  if Archi.splitlong then SplitLong.longofsingle e else 
+  Eop Olongofsingle (e:::Enil).
+
+Definition longuofsingle (e: expr) := 
+  if Archi.splitlong then SplitLong.longuofsingle e else 
+  Eop Olonguofsingle (e:::Enil).
+
+Definition singleoflong (e: expr) := 
+  if Archi.splitlong then SplitLong.singleoflong e else 
+  Eop Osingleoflong (e:::Enil).
+
+Definition singleoflongu (e: expr) := 
+  if Archi.splitlong then SplitLong.singleoflongu e else 
+  Eop Osingleoflongu (e:::Enil).
+
+End SELECT.