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(** The Mach intermediate language: abstract syntax.
Mach is the last intermediate language before generation of assembly
code. This file defines the abstract syntax for Mach; two dynamic
semantics are given in modules [Machabstr] and [Machconcr].
*)
Require Import Coqlib.
Require Import Maps.
Require Import AST.
Require Import Integers.
Require Import Values.
Require Import Mem.
Require Import Events.
Require Import Globalenvs.
Require Import Op.
Require Import Locations.
(** * Abstract syntax *)
(** Like Linear, the Mach language is organized as lists of instructions
operating over machine registers, with default fall-through behaviour
and explicit labels and branch instructions.
The main difference with Linear lies in the instructions used to
access the activation record. Mach has three such instructions:
[Mgetstack] and [Msetstack] to read and write within the activation
record for the current function, at a given word offset and with a
given type; and [Mgetparam], to read within the activation record of
the caller.
These instructions implement a more concrete view of the activation
record than the the [Lgetstack] and [Lsetstack] instructions of
Linear: actual offsets are used instead of abstract stack slots, and the
distinction between the caller's frame and the callee's frame is
made explicit. *)
Definition label := positive.
Inductive instruction: Set :=
| Mgetstack: int -> typ -> mreg -> instruction
| Msetstack: mreg -> int -> typ -> instruction
| Mgetparam: int -> typ -> mreg -> instruction
| Mop: operation -> list mreg -> mreg -> instruction
| Mload: memory_chunk -> addressing -> list mreg -> mreg -> instruction
| Mstore: memory_chunk -> addressing -> list mreg -> mreg -> instruction
| Mcall: signature -> mreg + ident -> instruction
| Mtailcall: signature -> mreg + ident -> instruction
| Malloc: instruction
| Mlabel: label -> instruction
| Mgoto: label -> instruction
| Mcond: condition -> list mreg -> label -> instruction
| Mreturn: instruction.
Definition code := list instruction.
Record function: Set := mkfunction
{ fn_sig: signature;
fn_code: code;
fn_stacksize: Z;
fn_framesize: Z }.
Definition fundef := AST.fundef function.
Definition program := AST.program fundef unit.
Definition funsig (fd: fundef) :=
match fd with
| Internal f => f.(fn_sig)
| External ef => ef.(ef_sig)
end.
Definition genv := Genv.t fundef.
(** * Dynamic semantics *)
Module RegEq.
Definition t := mreg.
Definition eq := mreg_eq.
End RegEq.
Module Regmap := EMap(RegEq).
Definition regset := Regmap.t val.
Notation "a ## b" := (List.map a b) (at level 1).
Notation "a # b <- c" := (Regmap.set b c a) (at level 1, b at next level).
Definition is_label (lbl: label) (instr: instruction) : bool :=
match instr with
| Mlabel lbl' => if peq lbl lbl' then true else false
| _ => false
end.
Lemma is_label_correct:
forall lbl instr,
if is_label lbl instr then instr = Mlabel lbl else instr <> Mlabel lbl.
Proof.
intros. destruct instr; simpl; try discriminate.
case (peq lbl l); intro; congruence.
Qed.
Fixpoint find_label (lbl: label) (c: code) {struct c} : option code :=
match c with
| nil => None
| i1 :: il => if is_label lbl i1 then Some il else find_label lbl il
end.
Lemma find_label_incl:
forall lbl c c', find_label lbl c = Some c' -> incl c' c.
Proof.
induction c; simpl; intros. discriminate.
destruct (is_label lbl a). inv H. auto with coqlib. eauto with coqlib.
Qed.
Definition find_function_ptr
(ge: genv) (ros: mreg + ident) (rs: regset) : option block :=
match ros with
| inl r =>
match rs r with
| Vptr b ofs => if Int.eq ofs Int.zero then Some b else None
| _ => None
end
| inr symb =>
Genv.find_symbol ge symb
end.
Definition align_16_top (lo hi: Z) :=
Zmax 0 (((hi - lo + 15) / 16) * 16 + lo).
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