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, 218 insertions, 0 deletions

diff --git a/riscV/ValueAOp.v b/riscV/ValueAOp.v
new file mode 100644
index 00000000..5670b5fe
--- /dev/null
+++ b/riscV/ValueAOp.v
@@ -0,0 +1,218 @@
+(* *********************************************************************)
+(*                                                                     *)
+(*              The Compcert verified compiler                         *)
+(*                                                                     *)
+(*                Xavier Leroy, INRIA Paris                            *)
+(*                                                                     *)
+(*  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.     *)
+(*                                                                     *)
+(* *********************************************************************)
+
+Require Import Coqlib Compopts.
+Require Import AST Integers Floats Values Memory Globalenvs.
+Require Import Op RTL ValueDomain.
+
+(** Value analysis for RISC V operators *)
+
+Definition eval_static_condition (cond: condition) (vl: list aval): abool :=
+  match cond, vl with
+  | Ccomp c, v1 :: v2 :: nil => cmp_bool c v1 v2
+  | Ccompu c, v1 :: v2 :: nil => cmpu_bool c v1 v2
+  | Ccompimm c n, v1 :: nil => cmp_bool c v1 (I n)
+  | Ccompuimm c n, v1 :: nil => cmpu_bool c v1 (I n)
+  | Ccompl c, v1 :: v2 :: nil => cmpl_bool c v1 v2
+  | Ccomplu c, v1 :: v2 :: nil => cmplu_bool c v1 v2
+  | Ccomplimm c n, v1 :: nil => cmpl_bool c v1 (L n)
+  | Ccompluimm c n, v1 :: nil => cmplu_bool c v1 (L n)
+  | Ccompf c, v1 :: v2 :: nil => cmpf_bool c v1 v2
+  | Cnotcompf c, v1 :: v2 :: nil => cnot (cmpf_bool c v1 v2)
+  | Ccompfs c, v1 :: v2 :: nil => cmpfs_bool c v1 v2
+  | Cnotcompfs c, v1 :: v2 :: nil => cnot (cmpfs_bool c v1 v2)
+  | _, _ => Bnone
+  end.
+
+Definition eval_static_addressing (addr: addressing) (vl: list aval): aval :=
+  match addr, vl with
+  | Aindexed n, v1::nil => offset_ptr v1 n
+  | Aglobal s ofs, nil => Ptr (Gl s ofs)
+  | Ainstack ofs, nil => Ptr (Stk ofs)
+  | _, _ => Vbot
+  end.
+
+Definition eval_static_operation (op: operation) (vl: list aval): aval :=
+  match op, vl with
+  | Omove, v1::nil => v1
+  | Ointconst n, nil => I n
+  | Olongconst n, nil => L n
+  | Ofloatconst n, nil => if propagate_float_constants tt then F n else ntop
+  | Osingleconst n, nil => if propagate_float_constants tt then FS n else ntop
+  | Oaddrsymbol id ofs, nil => Ptr (Gl id ofs)
+  | Oaddrstack ofs, nil => Ptr (Stk ofs)
+  | Ocast8signed, v1 :: nil => sign_ext 8 v1
+  | Ocast16signed, v1 :: nil => sign_ext 16 v1
+  | Oadd, v1::v2::nil => add v1 v2
+  | Oaddimm n, v1::nil => add v1 (I n)
+  | Oneg, v1::nil => neg v1
+  | Osub, v1::v2::nil => sub v1 v2
+  | Omul, v1::v2::nil => mul v1 v2
+  | Omulhs, v1::v2::nil => mulhs v1 v2
+  | Omulhu, v1::v2::nil => mulhu v1 v2
+  | Odiv, v1::v2::nil => divs v1 v2
+  | Odivu, v1::v2::nil => divu v1 v2
+  | Omod, v1::v2::nil => mods v1 v2
+  | Omodu, v1::v2::nil => modu v1 v2
+  | Oand, v1::v2::nil => and v1 v2
+  | Oandimm n, v1::nil => and v1 (I n)
+  | Oor, v1::v2::nil => or v1 v2
+  | Oorimm n, v1::nil => or v1 (I n)
+  | Oxor, v1::v2::nil => xor v1 v2
+  | Oxorimm n, v1::nil => xor v1 (I n)
+  | Oshl, v1::v2::nil => shl v1 v2
+  | Oshlimm n, v1::nil => shl v1 (I n)
+  | Oshr, v1::v2::nil => shr v1 v2
+  | Oshrimm n, v1::nil => shr v1 (I n)
+  | Oshru, v1::v2::nil => shru v1 v2
+  | Oshruimm n, v1::nil => shru v1 (I n)
+  | Oshrximm n, v1::nil => shrx v1 (I n)
+  | Omakelong, v1::v2::nil => longofwords v1 v2
+  | Olowlong, v1::nil => loword v1
+  | Ohighlong, v1::nil => hiword v1
+  | Ocast32signed, v1::nil => longofint v1
+  | Ocast32unsigned, v1::nil => longofintu v1
+  | Oaddl, v1::v2::nil => addl v1 v2
+  | Oaddlimm n, v1::nil => addl v1 (L n)
+  | Onegl, v1::nil => negl v1
+  | Osubl, v1::v2::nil => subl v1 v2
+  | Omull, v1::v2::nil => mull v1 v2
+  | Omullhs, v1::v2::nil => mullhs v1 v2
+  | Omullhu, v1::v2::nil => mullhu v1 v2
+  | Odivl, v1::v2::nil => divls v1 v2
+  | Odivlu, v1::v2::nil => divlu v1 v2
+  | Omodl, v1::v2::nil => modls v1 v2
+  | Omodlu, v1::v2::nil => modlu v1 v2
+  | Oandl, v1::v2::nil => andl v1 v2
+  | Oandlimm n, v1::nil => andl v1 (L n)
+  | Oorl, v1::v2::nil => orl v1 v2
+  | Oorlimm n, v1::nil => orl v1 (L n)
+  | Oxorl, v1::v2::nil => xorl v1 v2
+  | Oxorlimm n, v1::nil => xorl v1 (L n)
+  | Oshll, v1::v2::nil => shll v1 v2
+  | Oshllimm n, v1::nil => shll v1 (I n)
+  | Oshrl, v1::v2::nil => shrl v1 v2
+  | Oshrlimm n, v1::nil => shrl v1 (I n)
+  | Oshrlu, v1::v2::nil => shrlu v1 v2
+  | Oshrluimm n, v1::nil => shrlu v1 (I n)
+  | Oshrxlimm n, v1::nil => shrxl v1 (I n)
+  | Onegf, v1::nil => negf v1
+  | Oabsf, v1::nil => absf v1
+  | Oaddf, v1::v2::nil => addf v1 v2
+  | Osubf, v1::v2::nil => subf v1 v2
+  | Omulf, v1::v2::nil => mulf v1 v2
+  | Odivf, v1::v2::nil => divf v1 v2
+  | Onegfs, v1::nil => negfs v1
+  | Oabsfs, v1::nil => absfs v1
+  | Oaddfs, v1::v2::nil => addfs v1 v2
+  | Osubfs, v1::v2::nil => subfs v1 v2
+  | Omulfs, v1::v2::nil => mulfs v1 v2
+  | Odivfs, v1::v2::nil => divfs v1 v2
+  | Osingleoffloat, v1::nil => singleoffloat v1
+  | Ofloatofsingle, v1::nil => floatofsingle v1
+  | Ointoffloat, v1::nil => intoffloat v1
+  | Ointuoffloat, v1::nil => intuoffloat v1
+  | Ofloatofint, v1::nil => floatofint v1
+  | Ofloatofintu, v1::nil => floatofintu v1
+  | Ointofsingle, v1::nil => intofsingle v1
+  | Ointuofsingle, v1::nil => intuofsingle v1
+  | Osingleofint, v1::nil => singleofint v1
+  | Osingleofintu, v1::nil => singleofintu v1
+  | Olongoffloat, v1::nil => longoffloat v1
+  | Olonguoffloat, v1::nil => longuoffloat v1
+  | Ofloatoflong, v1::nil => floatoflong v1
+  | Ofloatoflongu, v1::nil => floatoflongu v1
+  | Olongofsingle, v1::nil => longofsingle v1
+  | Olonguofsingle, v1::nil => longuofsingle v1
+  | Osingleoflong, v1::nil => singleoflong v1
+  | Osingleoflongu, v1::nil => singleoflongu v1
+  | Ocmp c, _ => of_optbool (eval_static_condition c vl)
+  | _, _ => Vbot
+  end.
+
+Section SOUNDNESS.
+
+Variable bc: block_classification.
+Variable ge: genv.
+Hypothesis GENV: genv_match bc ge.
+Variable sp: block.
+Hypothesis STACK: bc sp = BCstack.
+
+Theorem eval_static_condition_sound:
+  forall cond vargs m aargs,
+  list_forall2 (vmatch bc) vargs aargs ->
+  cmatch (eval_condition cond vargs m) (eval_static_condition cond aargs).
+Proof.
+  intros until aargs; intros VM. inv VM.
+  destruct cond; auto with va.
+  inv H0.
+  destruct cond; simpl; eauto with va.
+  inv H2.
+  destruct cond; simpl; eauto with va.
+  destruct cond; auto with va.
+Qed.
+
+Lemma symbol_address_sound:
+  forall id ofs,
+  vmatch bc (Genv.symbol_address ge id ofs) (Ptr (Gl id ofs)).
+Proof.
+  intros; apply symbol_address_sound; apply GENV.
+Qed.
+
+Lemma symbol_address_sound_2:
+  forall id ofs,
+  vmatch bc (Genv.symbol_address ge id ofs) (Ifptr (Gl id ofs)).
+Proof.
+  intros. unfold Genv.symbol_address. destruct (Genv.find_symbol ge id) as [b|] eqn:F.
+  constructor. constructor. apply GENV; auto.
+  constructor.
+Qed.
+
+Hint Resolve symbol_address_sound symbol_address_sound_2: va.
+
+Ltac InvHyps :=
+  match goal with
+  | [H: None = Some _ |- _ ] => discriminate
+  | [H: Some _ = Some _ |- _] => inv H
+  | [H1: match ?vl with nil => _ | _ :: _ => _ end = Some _ ,
+     H2: list_forall2 _ ?vl _ |- _ ] => inv H2; InvHyps
+  | [H: (if Archi.ptr64 then _ else _) = Some _ |- _] => destruct Archi.ptr64 eqn:?; InvHyps
+  | _ => idtac
+  end.
+
+Theorem eval_static_addressing_sound:
+  forall addr vargs vres aargs,
+  eval_addressing ge (Vptr sp Ptrofs.zero) addr vargs = Some vres ->
+  list_forall2 (vmatch bc) vargs aargs ->
+  vmatch bc vres (eval_static_addressing addr aargs).
+Proof.
+  unfold eval_addressing, eval_static_addressing; intros;
+  destruct addr; InvHyps; eauto with va.
+  rewrite Ptrofs.add_zero_l; eauto with va.
+Qed.
+
+Theorem eval_static_operation_sound:
+  forall op vargs m vres aargs,
+  eval_operation ge (Vptr sp Ptrofs.zero) op vargs m = Some vres ->
+  list_forall2 (vmatch bc) vargs aargs ->
+  vmatch bc vres (eval_static_operation op aargs).
+Proof.
+  unfold eval_operation, eval_static_operation; intros;
+  destruct op; InvHyps; eauto with va.
+  destruct (propagate_float_constants tt); constructor.
+  destruct (propagate_float_constants tt); constructor.
+  rewrite Ptrofs.add_zero_l; eauto with va.
+  apply of_optbool_sound. eapply eval_static_condition_sound; eauto.
+Qed.
+
+End SOUNDNESS.
+