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+(* *********************************************************************)
+(*                                                                     *)
+(*              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.     *)
+(*                                                                     *)
+(* *********************************************************************)
+
+(** Machine- and ABI-dependent layout information for activation records. *)
+
+Require Import Coqlib.
+Require Import Bounds.
+
+(** In the PowerPC/EABI application binary interface,
+  the general shape of activation records is as follows,
+  from bottom (lowest offsets) to top:
+- 8 reserved bytes.  The first 4 bytes hold the back pointer to the
+  activation record of the caller.  The next 4 bytes hold the
+  return address.
+- Space for outgoing arguments to function calls.
+- Local stack slots of integer type.
+- Saved values of integer callee-save registers used by the function.
+- One word of padding, if necessary to align the following data
+  on a 8-byte boundary.
+- Local stack slots of float type.
+- Saved values of float callee-save registers used by the function.
+- Space for the stack-allocated data declared in Cminor.
+
+To facilitate some of the proofs, the Cminor stack-allocated data
+starts at offset 0; the preceding areas in the activation record
+therefore have negative offsets.  This part (with negative offsets)
+is called the ``frame'', by opposition with the ``Cminor stack data''
+which is the part with positive offsets.
+
+The [frame_env] compilation environment records the positions of
+the boundaries between areas in the frame part.
+*)
+
+Definition fe_ofs_arg := 8.
+
+Record frame_env : Set := mk_frame_env {
+  fe_size: Z;
+  fe_ofs_link: Z;
+  fe_ofs_retaddr: Z;
+  fe_ofs_int_local: Z;
+  fe_ofs_int_callee_save: Z;
+  fe_num_int_callee_save: Z;
+  fe_ofs_float_local: Z;
+  fe_ofs_float_callee_save: Z;
+  fe_num_float_callee_save: Z
+}.
+
+(** Computation of the frame environment from the bounds of the current
+  function. *)
+
+Definition make_env (b: bounds) :=
+  let oil := 8 + 4 * b.(bound_outgoing) in    (* integer locals *)
+  let oics := oil + 4 * b.(bound_int_local) in (* integer callee-saves *)
+  let oendi := oics + 4 * b.(bound_int_callee_save) in
+  let ofl := align oendi 8 in       (* float locals *)
+  let ofcs := ofl + 8 * b.(bound_float_local) in (* float callee-saves *)
+  let sz := ofcs + 8 * b.(bound_float_callee_save) in (* total frame size *)
+  mk_frame_env sz 0 4
+                  oil oics b.(bound_int_callee_save)
+                  ofl ofcs b.(bound_float_callee_save).
+
+
+Remark align_float_part:
+  forall b,
+  8 + 4 * bound_outgoing b + 4 * bound_int_local b + 4 * bound_int_callee_save b <=
+  align (8 + 4 * bound_outgoing b + 4 * bound_int_local b + 4 * bound_int_callee_save b) 8.
+Proof.
+  intros. apply align_le. omega.
+Qed.
+