+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- E X P _ P A K D --
--- --
--- B o d y --
--- --
--- $Revision: 1.2.10.1 $
--- --
--- Copyright (C) 1992-2001 Free Software Foundation, Inc. --
--- --
--- GNAT is free software; you can redistribute it and/or modify it under --
--- terms of the GNU General Public License as published by the Free Soft- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
--- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
--- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
--- --
--- GNAT was originally developed by the GNAT team at New York University. --
--- Extensive contributions were provided by Ada Core Technologies Inc. --
--- --
-------------------------------------------------------------------------------
-
-with Atree; use Atree;
-with Checks; use Checks;
-with Einfo; use Einfo;
-with Exp_Dbug; use Exp_Dbug;
-with Exp_Util; use Exp_Util;
-with Nlists; use Nlists;
-with Nmake; use Nmake;
-with Opt; use Opt;
-with Rtsfind; use Rtsfind;
-with Sem; use Sem;
-with Sem_Ch8; use Sem_Ch8;
-with Sem_Ch13; use Sem_Ch13;
-with Sem_Eval; use Sem_Eval;
-with Sem_Res; use Sem_Res;
-with Sem_Util; use Sem_Util;
-with Sinfo; use Sinfo;
-with Snames; use Snames;
-with Stand; use Stand;
-with Targparm; use Targparm;
-with Tbuild; use Tbuild;
-with Ttypes; use Ttypes;
-with Uintp; use Uintp;
-
-package body Exp_Pakd is
-
- ---------------------------
- -- Endian Considerations --
- ---------------------------
-
- -- As described in the specification, bit numbering in a packed array
- -- is consistent with bit numbering in a record representation clause,
- -- and hence dependent on the endianness of the machine:
-
- -- For little-endian machines, element zero is at the right hand end
- -- (low order end) of a bit field.
-
- -- For big-endian machines, element zero is at the left hand end
- -- (high order end) of a bit field.
-
- -- The shifts that are used to right justify a field therefore differ
- -- in the two cases. For the little-endian case, we can simply use the
- -- bit number (i.e. the element number * element size) as the count for
- -- a right shift. For the big-endian case, we have to subtract the shift
- -- count from an appropriate constant to use in the right shift. We use
- -- rotates instead of shifts (which is necessary in the store case to
- -- preserve other fields), and we expect that the backend will be able
- -- to change the right rotate into a left rotate, avoiding the subtract,
- -- if the architecture provides such an instruction.
-
- ----------------------------------------------
- -- Entity Tables for Packed Access Routines --
- ----------------------------------------------
-
- -- For the cases of component size = 3,5-7,9-15,17-31,33-63 we call
- -- library routines. This table is used to obtain the entity for the
- -- proper routine.
-
- type E_Array is array (Int range 01 .. 63) of RE_Id;
-
- -- Array of Bits_nn entities. Note that we do not use library routines
- -- for the 8-bit and 16-bit cases, but we still fill in the table, using
- -- entries from System.Unsigned, because we also use this table for
- -- certain special unchecked conversions in the big-endian case.
-
- Bits_Id : constant E_Array :=
- (01 => RE_Bits_1,
- 02 => RE_Bits_2,
- 03 => RE_Bits_03,
- 04 => RE_Bits_4,
- 05 => RE_Bits_05,
- 06 => RE_Bits_06,
- 07 => RE_Bits_07,
- 08 => RE_Unsigned_8,
- 09 => RE_Bits_09,
- 10 => RE_Bits_10,
- 11 => RE_Bits_11,
- 12 => RE_Bits_12,
- 13 => RE_Bits_13,
- 14 => RE_Bits_14,
- 15 => RE_Bits_15,
- 16 => RE_Unsigned_16,
- 17 => RE_Bits_17,
- 18 => RE_Bits_18,
- 19 => RE_Bits_19,
- 20 => RE_Bits_20,
- 21 => RE_Bits_21,
- 22 => RE_Bits_22,
- 23 => RE_Bits_23,
- 24 => RE_Bits_24,
- 25 => RE_Bits_25,
- 26 => RE_Bits_26,
- 27 => RE_Bits_27,
- 28 => RE_Bits_28,
- 29 => RE_Bits_29,
- 30 => RE_Bits_30,
- 31 => RE_Bits_31,
- 32 => RE_Unsigned_32,
- 33 => RE_Bits_33,
- 34 => RE_Bits_34,
- 35 => RE_Bits_35,
- 36 => RE_Bits_36,
- 37 => RE_Bits_37,
- 38 => RE_Bits_38,
- 39 => RE_Bits_39,
- 40 => RE_Bits_40,
- 41 => RE_Bits_41,
- 42 => RE_Bits_42,
- 43 => RE_Bits_43,
- 44 => RE_Bits_44,
- 45 => RE_Bits_45,
- 46 => RE_Bits_46,
- 47 => RE_Bits_47,
- 48 => RE_Bits_48,
- 49 => RE_Bits_49,
- 50 => RE_Bits_50,
- 51 => RE_Bits_51,
- 52 => RE_Bits_52,
- 53 => RE_Bits_53,
- 54 => RE_Bits_54,
- 55 => RE_Bits_55,
- 56 => RE_Bits_56,
- 57 => RE_Bits_57,
- 58 => RE_Bits_58,
- 59 => RE_Bits_59,
- 60 => RE_Bits_60,
- 61 => RE_Bits_61,
- 62 => RE_Bits_62,
- 63 => RE_Bits_63);
-
- -- Array of Get routine entities. These are used to obtain an element
- -- from a packed array. The N'th entry is used to obtain elements from
- -- a packed array whose component size is N. RE_Null is used as a null
- -- entry, for the cases where a library routine is not used.
-
- Get_Id : constant E_Array :=
- (01 => RE_Null,
- 02 => RE_Null,
- 03 => RE_Get_03,
- 04 => RE_Null,
- 05 => RE_Get_05,
- 06 => RE_Get_06,
- 07 => RE_Get_07,
- 08 => RE_Null,
- 09 => RE_Get_09,
- 10 => RE_Get_10,
- 11 => RE_Get_11,
- 12 => RE_Get_12,
- 13 => RE_Get_13,
- 14 => RE_Get_14,
- 15 => RE_Get_15,
- 16 => RE_Null,
- 17 => RE_Get_17,
- 18 => RE_Get_18,
- 19 => RE_Get_19,
- 20 => RE_Get_20,
- 21 => RE_Get_21,
- 22 => RE_Get_22,
- 23 => RE_Get_23,
- 24 => RE_Get_24,
- 25 => RE_Get_25,
- 26 => RE_Get_26,
- 27 => RE_Get_27,
- 28 => RE_Get_28,
- 29 => RE_Get_29,
- 30 => RE_Get_30,
- 31 => RE_Get_31,
- 32 => RE_Null,
- 33 => RE_Get_33,
- 34 => RE_Get_34,
- 35 => RE_Get_35,
- 36 => RE_Get_36,
- 37 => RE_Get_37,
- 38 => RE_Get_38,
- 39 => RE_Get_39,
- 40 => RE_Get_40,
- 41 => RE_Get_41,
- 42 => RE_Get_42,
- 43 => RE_Get_43,
- 44 => RE_Get_44,
- 45 => RE_Get_45,
- 46 => RE_Get_46,
- 47 => RE_Get_47,
- 48 => RE_Get_48,
- 49 => RE_Get_49,
- 50 => RE_Get_50,
- 51 => RE_Get_51,
- 52 => RE_Get_52,
- 53 => RE_Get_53,
- 54 => RE_Get_54,
- 55 => RE_Get_55,
- 56 => RE_Get_56,
- 57 => RE_Get_57,
- 58 => RE_Get_58,
- 59 => RE_Get_59,
- 60 => RE_Get_60,
- 61 => RE_Get_61,
- 62 => RE_Get_62,
- 63 => RE_Get_63);
-
- -- Array of Get routine entities to be used in the case where the packed
- -- array is itself a component of a packed structure, and therefore may
- -- not be fully aligned. This only affects the even sizes, since for the
- -- odd sizes, we do not get any fixed alignment in any case.
-
- GetU_Id : constant E_Array :=
- (01 => RE_Null,
- 02 => RE_Null,
- 03 => RE_Get_03,
- 04 => RE_Null,
- 05 => RE_Get_05,
- 06 => RE_GetU_06,
- 07 => RE_Get_07,
- 08 => RE_Null,
- 09 => RE_Get_09,
- 10 => RE_GetU_10,
- 11 => RE_Get_11,
- 12 => RE_GetU_12,
- 13 => RE_Get_13,
- 14 => RE_GetU_14,
- 15 => RE_Get_15,
- 16 => RE_Null,
- 17 => RE_Get_17,
- 18 => RE_GetU_18,
- 19 => RE_Get_19,
- 20 => RE_GetU_20,
- 21 => RE_Get_21,
- 22 => RE_GetU_22,
- 23 => RE_Get_23,
- 24 => RE_GetU_24,
- 25 => RE_Get_25,
- 26 => RE_GetU_26,
- 27 => RE_Get_27,
- 28 => RE_GetU_28,
- 29 => RE_Get_29,
- 30 => RE_GetU_30,
- 31 => RE_Get_31,
- 32 => RE_Null,
- 33 => RE_Get_33,
- 34 => RE_GetU_34,
- 35 => RE_Get_35,
- 36 => RE_GetU_36,
- 37 => RE_Get_37,
- 38 => RE_GetU_38,
- 39 => RE_Get_39,
- 40 => RE_GetU_40,
- 41 => RE_Get_41,
- 42 => RE_GetU_42,
- 43 => RE_Get_43,
- 44 => RE_GetU_44,
- 45 => RE_Get_45,
- 46 => RE_GetU_46,
- 47 => RE_Get_47,
- 48 => RE_GetU_48,
- 49 => RE_Get_49,
- 50 => RE_GetU_50,
- 51 => RE_Get_51,
- 52 => RE_GetU_52,
- 53 => RE_Get_53,
- 54 => RE_GetU_54,
- 55 => RE_Get_55,
- 56 => RE_GetU_56,
- 57 => RE_Get_57,
- 58 => RE_GetU_58,
- 59 => RE_Get_59,
- 60 => RE_GetU_60,
- 61 => RE_Get_61,
- 62 => RE_GetU_62,
- 63 => RE_Get_63);
-
- -- Array of Set routine entities. These are used to assign an element
- -- of a packed array. The N'th entry is used to assign elements for
- -- a packed array whose component size is N. RE_Null is used as a null
- -- entry, for the cases where a library routine is not used.
-
- Set_Id : E_Array :=
- (01 => RE_Null,
- 02 => RE_Null,
- 03 => RE_Set_03,
- 04 => RE_Null,
- 05 => RE_Set_05,
- 06 => RE_Set_06,
- 07 => RE_Set_07,
- 08 => RE_Null,
- 09 => RE_Set_09,
- 10 => RE_Set_10,
- 11 => RE_Set_11,
- 12 => RE_Set_12,
- 13 => RE_Set_13,
- 14 => RE_Set_14,
- 15 => RE_Set_15,
- 16 => RE_Null,
- 17 => RE_Set_17,
- 18 => RE_Set_18,
- 19 => RE_Set_19,
- 20 => RE_Set_20,
- 21 => RE_Set_21,
- 22 => RE_Set_22,
- 23 => RE_Set_23,
- 24 => RE_Set_24,
- 25 => RE_Set_25,
- 26 => RE_Set_26,
- 27 => RE_Set_27,
- 28 => RE_Set_28,
- 29 => RE_Set_29,
- 30 => RE_Set_30,
- 31 => RE_Set_31,
- 32 => RE_Null,
- 33 => RE_Set_33,
- 34 => RE_Set_34,
- 35 => RE_Set_35,
- 36 => RE_Set_36,
- 37 => RE_Set_37,
- 38 => RE_Set_38,
- 39 => RE_Set_39,
- 40 => RE_Set_40,
- 41 => RE_Set_41,
- 42 => RE_Set_42,
- 43 => RE_Set_43,
- 44 => RE_Set_44,
- 45 => RE_Set_45,
- 46 => RE_Set_46,
- 47 => RE_Set_47,
- 48 => RE_Set_48,
- 49 => RE_Set_49,
- 50 => RE_Set_50,
- 51 => RE_Set_51,
- 52 => RE_Set_52,
- 53 => RE_Set_53,
- 54 => RE_Set_54,
- 55 => RE_Set_55,
- 56 => RE_Set_56,
- 57 => RE_Set_57,
- 58 => RE_Set_58,
- 59 => RE_Set_59,
- 60 => RE_Set_60,
- 61 => RE_Set_61,
- 62 => RE_Set_62,
- 63 => RE_Set_63);
-
- -- Array of Set routine entities to be used in the case where the packed
- -- array is itself a component of a packed structure, and therefore may
- -- not be fully aligned. This only affects the even sizes, since for the
- -- odd sizes, we do not get any fixed alignment in any case.
-
- SetU_Id : E_Array :=
- (01 => RE_Null,
- 02 => RE_Null,
- 03 => RE_Set_03,
- 04 => RE_Null,
- 05 => RE_Set_05,
- 06 => RE_SetU_06,
- 07 => RE_Set_07,
- 08 => RE_Null,
- 09 => RE_Set_09,
- 10 => RE_SetU_10,
- 11 => RE_Set_11,
- 12 => RE_SetU_12,
- 13 => RE_Set_13,
- 14 => RE_SetU_14,
- 15 => RE_Set_15,
- 16 => RE_Null,
- 17 => RE_Set_17,
- 18 => RE_SetU_18,
- 19 => RE_Set_19,
- 20 => RE_SetU_20,
- 21 => RE_Set_21,
- 22 => RE_SetU_22,
- 23 => RE_Set_23,
- 24 => RE_SetU_24,
- 25 => RE_Set_25,
- 26 => RE_SetU_26,
- 27 => RE_Set_27,
- 28 => RE_SetU_28,
- 29 => RE_Set_29,
- 30 => RE_SetU_30,
- 31 => RE_Set_31,
- 32 => RE_Null,
- 33 => RE_Set_33,
- 34 => RE_SetU_34,
- 35 => RE_Set_35,
- 36 => RE_SetU_36,
- 37 => RE_Set_37,
- 38 => RE_SetU_38,
- 39 => RE_Set_39,
- 40 => RE_SetU_40,
- 41 => RE_Set_41,
- 42 => RE_SetU_42,
- 43 => RE_Set_43,
- 44 => RE_SetU_44,
- 45 => RE_Set_45,
- 46 => RE_SetU_46,
- 47 => RE_Set_47,
- 48 => RE_SetU_48,
- 49 => RE_Set_49,
- 50 => RE_SetU_50,
- 51 => RE_Set_51,
- 52 => RE_SetU_52,
- 53 => RE_Set_53,
- 54 => RE_SetU_54,
- 55 => RE_Set_55,
- 56 => RE_SetU_56,
- 57 => RE_Set_57,
- 58 => RE_SetU_58,
- 59 => RE_Set_59,
- 60 => RE_SetU_60,
- 61 => RE_Set_61,
- 62 => RE_SetU_62,
- 63 => RE_Set_63);
-
- -----------------------
- -- Local Subprograms --
- -----------------------
-
- procedure Compute_Linear_Subscript
- (Atyp : Entity_Id;
- N : Node_Id;
- Subscr : out Node_Id);
- -- Given a constrained array type Atyp, and an indexed component node
- -- N referencing an array object of this type, build an expression of
- -- type Standard.Integer representing the zero-based linear subscript
- -- value. This expression includes any required range checks.
-
- procedure Convert_To_PAT_Type (Aexp : Node_Id);
- -- Given an expression of a packed array type, builds a corresponding
- -- expression whose type is the implementation type used to represent
- -- the packed array. Aexp is analyzed and resolved on entry and on exit.
-
- function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean;
- -- There are two versions of the Set routines, the ones used when the
- -- object is known to be sufficiently well aligned given the number of
- -- bits, and the ones used when the object is not known to be aligned.
- -- This routine is used to determine which set to use. Obj is a reference
- -- to the object, and Csiz is the component size of the packed array.
- -- True is returned if the alignment of object is known to be sufficient,
- -- defined as 1 for odd bit sizes, 4 for bit sizes divisible by 4, and
- -- 2 otherwise.
-
- function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id;
- -- Build a left shift node, checking for the case of a shift count of zero
-
- function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id;
- -- Build a right shift node, checking for the case of a shift count of zero
-
- function RJ_Unchecked_Convert_To
- (Typ : Entity_Id;
- Expr : Node_Id)
- return Node_Id;
- -- The packed array code does unchecked conversions which in some cases
- -- may involve non-discrete types with differing sizes. The semantics of
- -- such conversions is potentially endian dependent, and the effect we
- -- want here for such a conversion is to do the conversion in size as
- -- though numeric items are involved, and we extend or truncate on the
- -- left side. This happens naturally in the little-endian case, but in
- -- the big endian case we can get left justification, when what we want
- -- is right justification. This routine does the unchecked conversion in
- -- a stepwise manner to ensure that it gives the expected result. Hence
- -- the name (RJ = Right justified). The parameters Typ and Expr are as
- -- for the case of a normal Unchecked_Convert_To call.
-
- procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id);
- -- This routine is called in the Get and Set case for arrays that are
- -- packed but not bit-packed, meaning that they have at least one
- -- subscript that is of an enumeration type with a non-standard
- -- representation. This routine modifies the given node to properly
- -- reference the corresponding packed array type.
-
- procedure Setup_Inline_Packed_Array_Reference
- (N : Node_Id;
- Atyp : Entity_Id;
- Obj : in out Node_Id;
- Cmask : out Uint;
- Shift : out Node_Id);
- -- This procedure performs common processing on the N_Indexed_Component
- -- parameter given as N, whose prefix is a reference to a packed array.
- -- This is used for the get and set when the component size is 1,2,4
- -- or for other component sizes when the packed array type is a modular
- -- type (i.e. the cases that are handled with inline code).
- --
- -- On entry:
- --
- -- N is the N_Indexed_Component node for the packed array reference
- --
- -- Atyp is the constrained array type (the actual subtype has been
- -- computed if necessary to obtain the constraints, but this is still
- -- the original array type, not the Packed_Array_Type value).
- --
- -- Obj is the object which is to be indexed. It is always of type Atyp.
- --
- -- On return:
- --
- -- Obj is the object containing the desired bit field. It is of type
- -- Unsigned or Long_Long_Unsigned, and is either the entire value,
- -- for the small static case, or the proper selected byte from the
- -- array in the large or dynamic case. This node is analyzed and
- -- resolved on return.
- --
- -- Shift is a node representing the shift count to be used in the
- -- rotate right instruction that positions the field for access.
- -- This node is analyzed and resolved on return.
- --
- -- Cmask is a mask corresponding to the width of the component field.
- -- Its value is 2 ** Csize - 1 (e.g. 2#1111# for component size of 4).
- --
- -- Note: in some cases the call to this routine may generate actions
- -- (for handling multi-use references and the generation of the packed
- -- array type on the fly). Such actions are inserted into the tree
- -- directly using Insert_Action.
-
- ------------------------------
- -- Compute_Linear_Subcsript --
- ------------------------------
-
- procedure Compute_Linear_Subscript
- (Atyp : Entity_Id;
- N : Node_Id;
- Subscr : out Node_Id)
- is
- Loc : constant Source_Ptr := Sloc (N);
- Oldsub : Node_Id;
- Newsub : Node_Id;
- Indx : Node_Id;
- Styp : Entity_Id;
-
- begin
- Subscr := Empty;
-
- -- Loop through dimensions
-
- Indx := First_Index (Atyp);
- Oldsub := First (Expressions (N));
-
- while Present (Indx) loop
- Styp := Etype (Indx);
- Newsub := Relocate_Node (Oldsub);
-
- -- Get expression for the subscript value. First, if Do_Range_Check
- -- is set on a subscript, then we must do a range check against the
- -- original bounds (not the bounds of the packed array type). We do
- -- this by introducing a subtype conversion.
-
- if Do_Range_Check (Newsub)
- and then Etype (Newsub) /= Styp
- then
- Newsub := Convert_To (Styp, Newsub);
- end if;
-
- -- Now evolve the expression for the subscript. First convert
- -- the subscript to be zero based and of an integer type.
-
- -- Case of integer type, where we just subtract to get lower bound
-
- if Is_Integer_Type (Styp) then
-
- -- If length of integer type is smaller than standard integer,
- -- then we convert to integer first, then do the subtract
-
- -- Integer (subscript) - Integer (Styp'First)
-
- if Esize (Styp) < Esize (Standard_Integer) then
- Newsub :=
- Make_Op_Subtract (Loc,
- Left_Opnd => Convert_To (Standard_Integer, Newsub),
- Right_Opnd =>
- Convert_To (Standard_Integer,
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Styp, Loc),
- Attribute_Name => Name_First)));
-
- -- For larger integer types, subtract first, then convert to
- -- integer, this deals with strange long long integer bounds.
-
- -- Integer (subscript - Styp'First)
-
- else
- Newsub :=
- Convert_To (Standard_Integer,
- Make_Op_Subtract (Loc,
- Left_Opnd => Newsub,
- Right_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Styp, Loc),
- Attribute_Name => Name_First)));
- end if;
-
- -- For the enumeration case, we have to use 'Pos to get the value
- -- to work with before subtracting the lower bound.
-
- -- Integer (Styp'Pos (subscr)) - Integer (Styp'Pos (Styp'First));
-
- -- This is not quite right for bizarre cases where the size of the
- -- enumeration type is > Integer'Size bits due to rep clause ???
-
- else
- pragma Assert (Is_Enumeration_Type (Styp));
-
- Newsub :=
- Make_Op_Subtract (Loc,
- Left_Opnd => Convert_To (Standard_Integer,
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Styp, Loc),
- Attribute_Name => Name_Pos,
- Expressions => New_List (Newsub))),
-
- Right_Opnd =>
- Convert_To (Standard_Integer,
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Styp, Loc),
- Attribute_Name => Name_Pos,
- Expressions => New_List (
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Styp, Loc),
- Attribute_Name => Name_First)))));
- end if;
-
- Set_Paren_Count (Newsub, 1);
-
- -- For the first subscript, we just copy that subscript value
-
- if No (Subscr) then
- Subscr := Newsub;
-
- -- Otherwise, we must multiply what we already have by the current
- -- stride and then add in the new value to the evolving subscript.
-
- else
- Subscr :=
- Make_Op_Add (Loc,
- Left_Opnd =>
- Make_Op_Multiply (Loc,
- Left_Opnd => Subscr,
- Right_Opnd =>
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Range_Length,
- Prefix => New_Occurrence_Of (Styp, Loc))),
- Right_Opnd => Newsub);
- end if;
-
- -- Move to next subscript
-
- Next_Index (Indx);
- Next (Oldsub);
- end loop;
- end Compute_Linear_Subscript;
-
- -------------------------
- -- Convert_To_PAT_Type --
- -------------------------
-
- -- The PAT is always obtained from the actual subtype
-
- procedure Convert_To_PAT_Type (Aexp : Entity_Id) is
- Act_ST : Entity_Id;
-
- begin
- Convert_To_Actual_Subtype (Aexp);
- Act_ST := Underlying_Type (Etype (Aexp));
- Create_Packed_Array_Type (Act_ST);
-
- -- Just replace the etype with the packed array type. This works
- -- because the expression will not be further analyzed, and Gigi
- -- considers the two types equivalent in any case.
-
- Set_Etype (Aexp, Packed_Array_Type (Act_ST));
- end Convert_To_PAT_Type;
-
- ------------------------------
- -- Create_Packed_Array_Type --
- ------------------------------
-
- procedure Create_Packed_Array_Type (Typ : Entity_Id) is
- Loc : constant Source_Ptr := Sloc (Typ);
- Ctyp : constant Entity_Id := Component_Type (Typ);
- Csize : constant Uint := Component_Size (Typ);
-
- Ancest : Entity_Id;
- PB_Type : Entity_Id;
- Esiz : Uint;
- Decl : Node_Id;
- PAT : Entity_Id;
- Len_Dim : Node_Id;
- Len_Expr : Node_Id;
- Len_Bits : Uint;
- Bits_U1 : Node_Id;
- PAT_High : Node_Id;
- Btyp : Entity_Id;
- Lit : Node_Id;
-
- procedure Install_PAT;
- -- This procedure is called with Decl set to the declaration for the
- -- packed array type. It creates the type and installs it as required.
-
- procedure Set_PB_Type;
- -- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
- -- requirements (see documentation in the spec of this package).
-
- -----------------
- -- Install_PAT --
- -----------------
-
- procedure Install_PAT is
- Pushed_Scope : Boolean := False;
-
- begin
- -- We do not want to put the declaration we have created in the tree
- -- since it is often hard, and sometimes impossible to find a proper
- -- place for it (the impossible case arises for a packed array type
- -- with bounds depending on the discriminant, a declaration cannot
- -- be put inside the record, and the reference to the discriminant
- -- cannot be outside the record).
-
- -- The solution is to analyze the declaration while temporarily
- -- attached to the tree at an appropriate point, and then we install
- -- the resulting type as an Itype in the packed array type field of
- -- the original type, so that no explicit declaration is required.
-
- -- Note: the packed type is created in the scope of its parent
- -- type. There are at least some cases where the current scope
- -- is deeper, and so when this is the case, we temporarily reset
- -- the scope for the definition. This is clearly safe, since the
- -- first use of the packed array type will be the implicit
- -- reference from the corresponding unpacked type when it is
- -- elaborated.
-
- if Is_Itype (Typ) then
- Set_Parent (Decl, Associated_Node_For_Itype (Typ));
- else
- Set_Parent (Decl, Declaration_Node (Typ));
- end if;
-
- if Scope (Typ) /= Current_Scope then
- New_Scope (Scope (Typ));
- Pushed_Scope := True;
- end if;
-
- Set_Is_Itype (PAT, True);
- Set_Is_Packed_Array_Type (PAT, True);
- Analyze (Decl, Suppress => All_Checks);
-
- if Pushed_Scope then
- Pop_Scope;
- end if;
-
- -- Set Esize and RM_Size to the actual size of the packed object
- -- Do not reset RM_Size if already set, as happens in the case
- -- of a modular type
-
- Set_Esize (PAT, Esiz);
-
- if Unknown_RM_Size (PAT) then
- Set_RM_Size (PAT, Esiz);
- end if;
-
- -- Set remaining fields of packed array type
-
- Init_Alignment (PAT);
- Set_Parent (PAT, Empty);
- Set_Packed_Array_Type (Typ, PAT);
- Set_Associated_Node_For_Itype (PAT, Typ);
-
- -- We definitely do not want to delay freezing for packed array
- -- types. This is of particular importance for the itypes that
- -- are generated for record components depending on discriminants
- -- where there is no place to put the freeze node.
-
- Set_Has_Delayed_Freeze (PAT, False);
- Set_Has_Delayed_Freeze (Etype (PAT), False);
- end Install_PAT;
-
- -----------------
- -- Set_PB_Type --
- -----------------
-
- procedure Set_PB_Type is
- begin
- -- If the user has specified an explicit alignment for the
- -- component, take it into account.
-
- if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0
- or else Component_Alignment (Typ) = Calign_Storage_Unit
- then
- PB_Type := RTE (RE_Packed_Bytes1);
-
- elsif Csize mod 4 /= 0 then
- PB_Type := RTE (RE_Packed_Bytes2);
-
- else
- PB_Type := RTE (RE_Packed_Bytes4);
- end if;
- end Set_PB_Type;
-
- -- Start of processing for Create_Packed_Array_Type
-
- begin
- -- If we already have a packed array type, nothing to do
-
- if Present (Packed_Array_Type (Typ)) then
- return;
- end if;
-
- -- If our immediate ancestor subtype is constrained, and it already
- -- has a packed array type, then just share the same type, since the
- -- bounds must be the same.
-
- if Ekind (Typ) = E_Array_Subtype then
- Ancest := Ancestor_Subtype (Typ);
-
- if Present (Ancest)
- and then Is_Constrained (Ancest)
- and then Present (Packed_Array_Type (Ancest))
- then
- Set_Packed_Array_Type (Typ, Packed_Array_Type (Ancest));
- return;
- end if;
- end if;
-
- -- We preset the result type size from the size of the original array
- -- type, since this size clearly belongs to the packed array type. The
- -- size of the conceptual unpacked type is always set to unknown.
-
- Esiz := Esize (Typ);
-
- -- Case of an array where at least one index is of an enumeration
- -- type with a non-standard representation, but the component size
- -- is not appropriate for bit packing. This is the case where we
- -- have Is_Packed set (we would never be in this unit otherwise),
- -- but Is_Bit_Packed_Array is false.
-
- -- Note that if the component size is appropriate for bit packing,
- -- then the circuit for the computation of the subscript properly
- -- deals with the non-standard enumeration type case by taking the
- -- Pos anyway.
-
- if not Is_Bit_Packed_Array (Typ) then
-
- -- Here we build a declaration:
-
- -- type tttP is array (index1, index2, ...) of component_type
-
- -- where index1, index2, are the index types. These are the same
- -- as the index types of the original array, except for the non-
- -- standard representation enumeration type case, where we have
- -- two subcases.
-
- -- For the unconstrained array case, we use
-
- -- Natural range <>
-
- -- For the constrained case, we use
-
- -- Natural range Enum_Type'Pos (Enum_Type'First) ..
- -- Enum_Type'Pos (Enum_Type'Last);
-
- PAT :=
- Make_Defining_Identifier (Loc,
- Chars => New_External_Name (Chars (Typ), 'P'));
-
- Set_Packed_Array_Type (Typ, PAT);
-
- declare
- Indexes : List_Id := New_List;
- Indx : Node_Id;
- Indx_Typ : Entity_Id;
- Enum_Case : Boolean;
- Typedef : Node_Id;
-
- begin
- Indx := First_Index (Typ);
-
- while Present (Indx) loop
- Indx_Typ := Etype (Indx);
-
- Enum_Case := Is_Enumeration_Type (Indx_Typ)
- and then Has_Non_Standard_Rep (Indx_Typ);
-
- -- Unconstrained case
-
- if not Is_Constrained (Typ) then
- if Enum_Case then
- Indx_Typ := Standard_Natural;
- end if;
-
- Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
-
- -- Constrained case
-
- else
- if not Enum_Case then
- Append_To (Indexes, New_Occurrence_Of (Indx_Typ, Loc));
-
- else
- Append_To (Indexes,
- Make_Subtype_Indication (Loc,
- Subtype_Mark =>
- New_Occurrence_Of (Standard_Natural, Loc),
- Constraint =>
- Make_Range_Constraint (Loc,
- Range_Expression =>
- Make_Range (Loc,
- Low_Bound =>
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of (Indx_Typ, Loc),
- Attribute_Name => Name_Pos,
- Expressions => New_List (
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of (Indx_Typ, Loc),
- Attribute_Name => Name_First))),
-
- High_Bound =>
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of (Indx_Typ, Loc),
- Attribute_Name => Name_Pos,
- Expressions => New_List (
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of (Indx_Typ, Loc),
- Attribute_Name => Name_Last)))))));
-
- end if;
- end if;
-
- Next_Index (Indx);
- end loop;
-
- if not Is_Constrained (Typ) then
- Typedef :=
- Make_Unconstrained_Array_Definition (Loc,
- Subtype_Marks => Indexes,
- Subtype_Indication =>
- New_Occurrence_Of (Ctyp, Loc));
-
- else
- Typedef :=
- Make_Constrained_Array_Definition (Loc,
- Discrete_Subtype_Definitions => Indexes,
- Subtype_Indication =>
- New_Occurrence_Of (Ctyp, Loc));
- end if;
-
- Decl :=
- Make_Full_Type_Declaration (Loc,
- Defining_Identifier => PAT,
- Type_Definition => Typedef);
- end;
-
- Install_PAT;
- return;
-
- -- Case of bit-packing required for unconstrained array. We simply
- -- use Packed_Bytes{1,2,4} as appropriate, and we do not need to
- -- construct a special packed array type.
-
- elsif not Is_Constrained (Typ) then
- Set_PB_Type;
- Set_Packed_Array_Type (Typ, PB_Type);
- Set_Is_Packed_Array_Type (Packed_Array_Type (Typ), True);
- return;
-
- -- Remaining code is for the case of bit-packing for constrained array
-
- -- The name of the packed array subtype is
-
- -- ttt___Xsss
-
- -- where sss is the component size in bits and ttt is the name of
- -- the parent packed type.
-
- else
- PAT :=
- Make_Defining_Identifier (Loc,
- Chars => Make_Packed_Array_Type_Name (Typ, Csize));
-
- Set_Packed_Array_Type (Typ, PAT);
-
- -- Build an expression for the length of the array in bits.
- -- This is the product of the length of each of the dimensions
-
- declare
- J : Nat := 1;
-
- begin
- Len_Expr := Empty; -- suppress junk warning
-
- loop
- Len_Dim :=
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Length,
- Prefix => New_Occurrence_Of (Typ, Loc),
- Expressions => New_List (
- Make_Integer_Literal (Loc, J)));
-
- if J = 1 then
- Len_Expr := Len_Dim;
-
- else
- Len_Expr :=
- Make_Op_Multiply (Loc,
- Left_Opnd => Len_Expr,
- Right_Opnd => Len_Dim);
- end if;
-
- J := J + 1;
- exit when J > Number_Dimensions (Typ);
- end loop;
- end;
-
- -- Temporarily attach the length expression to the tree and analyze
- -- and resolve it, so that we can test its value. We assume that the
- -- total length fits in type Integer.
-
- Set_Parent (Len_Expr, Typ);
- Analyze_And_Resolve (Len_Expr, Standard_Integer);
-
- -- Use a modular type if possible. We can do this if we are we
- -- have static bounds, and the length is small enough, and the
- -- length is not zero. We exclude the zero length case because the
- -- size of things is always at least one, and the zero length object
- -- would have an anomous size
-
- if Compile_Time_Known_Value (Len_Expr) then
- Len_Bits := Expr_Value (Len_Expr) * Csize;
-
- -- We normally consider small enough to mean no larger than the
- -- value of System_Max_Binary_Modulus_Power, except that in
- -- No_Run_Time mode, we use the Word Size on machines for
- -- which double length shifts are not generated in line.
-
- if Len_Bits > 0
- and then
- (Len_Bits <= System_Word_Size
- or else (Len_Bits <= System_Max_Binary_Modulus_Power
- and then (not No_Run_Time
- or else
- Long_Shifts_Inlined_On_Target)))
- then
- -- We can use the modular type, it has the form:
-
- -- subtype tttPn is btyp
- -- range 0 .. 2 ** (Esize (Typ) * Csize) - 1;
-
- -- Here Siz is 1, 2 or 4, as computed above, and btyp is either
- -- Unsigned or Long_Long_Unsigned depending on the length.
-
- if Len_Bits <= Standard_Integer_Size then
- Btyp := RTE (RE_Unsigned);
- else
- Btyp := RTE (RE_Long_Long_Unsigned);
- end if;
-
- Lit := Make_Integer_Literal (Loc, 2 ** Len_Bits - 1);
- Set_Print_In_Hex (Lit);
-
- Decl :=
- Make_Subtype_Declaration (Loc,
- Defining_Identifier => PAT,
- Subtype_Indication =>
- Make_Subtype_Indication (Loc,
- Subtype_Mark => New_Occurrence_Of (Btyp, Loc),
-
- Constraint =>
- Make_Range_Constraint (Loc,
- Range_Expression =>
- Make_Range (Loc,
- Low_Bound =>
- Make_Integer_Literal (Loc, 0),
- High_Bound => Lit))));
-
- if Esiz = Uint_0 then
- Esiz := Len_Bits;
- end if;
-
- Install_PAT;
- return;
- end if;
- end if;
-
- -- Could not use a modular type, for all other cases, we build
- -- a packed array subtype:
-
- -- subtype tttPn is
- -- System.Packed_Bytes{1,2,4} (0 .. (Bits + 7) / 8 - 1);
-
- -- Bits is the length of the array in bits.
-
- Set_PB_Type;
-
- Bits_U1 :=
- Make_Op_Add (Loc,
- Left_Opnd =>
- Make_Op_Multiply (Loc,
- Left_Opnd =>
- Make_Integer_Literal (Loc, Csize),
- Right_Opnd => Len_Expr),
-
- Right_Opnd =>
- Make_Integer_Literal (Loc, 7));
-
- Set_Paren_Count (Bits_U1, 1);
-
- PAT_High :=
- Make_Op_Subtract (Loc,
- Left_Opnd =>
- Make_Op_Divide (Loc,
- Left_Opnd => Bits_U1,
- Right_Opnd => Make_Integer_Literal (Loc, 8)),
- Right_Opnd => Make_Integer_Literal (Loc, 1));
-
- Decl :=
- Make_Subtype_Declaration (Loc,
- Defining_Identifier => PAT,
- Subtype_Indication =>
- Make_Subtype_Indication (Loc,
- Subtype_Mark => New_Occurrence_Of (PB_Type, Loc),
- Constraint =>
-
- Make_Index_Or_Discriminant_Constraint (Loc,
- Constraints => New_List (
- Make_Range (Loc,
- Low_Bound =>
- Make_Integer_Literal (Loc, 0),
- High_Bound => PAT_High)))));
-
- Install_PAT;
- end if;
- end Create_Packed_Array_Type;
-
- -----------------------------------
- -- Expand_Bit_Packed_Element_Set --
- -----------------------------------
-
- procedure Expand_Bit_Packed_Element_Set (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Lhs : constant Node_Id := Name (N);
-
- Ass_OK : constant Boolean := Assignment_OK (Lhs);
- -- Used to preserve assignment OK status when assignment is rewritten
-
- Rhs : Node_Id := Expression (N);
- -- Initially Rhs is the right hand side value, it will be replaced
- -- later by an appropriate unchecked conversion for the assignment.
-
- Obj : Node_Id;
- Atyp : Entity_Id;
- PAT : Entity_Id;
- Ctyp : Entity_Id;
- Csiz : Int;
- Shift : Node_Id;
- Cmask : Uint;
-
- New_Lhs : Node_Id;
- New_Rhs : Node_Id;
-
- Rhs_Val_Known : Boolean;
- Rhs_Val : Uint;
- -- If the value of the right hand side as an integer constant is
- -- known at compile time, Rhs_Val_Known is set True, and Rhs_Val
- -- contains the value. Otherwise Rhs_Val_Known is set False, and
- -- the Rhs_Val is undefined.
-
- begin
- pragma Assert (Is_Bit_Packed_Array (Etype (Prefix (Lhs))));
-
- Obj := Relocate_Node (Prefix (Lhs));
- Convert_To_Actual_Subtype (Obj);
- Atyp := Etype (Obj);
- PAT := Packed_Array_Type (Atyp);
- Ctyp := Component_Type (Atyp);
- Csiz := UI_To_Int (Component_Size (Atyp));
-
- -- We convert the right hand side to the proper subtype to ensure
- -- that an appropriate range check is made (since the normal range
- -- check from assignment will be lost in the transformations). This
- -- conversion is analyzed immediately so that subsequent processing
- -- can work with an analyzed Rhs (and e.g. look at its Etype)
-
- Rhs := Convert_To (Ctyp, Rhs);
- Set_Parent (Rhs, N);
- Analyze_And_Resolve (Rhs, Ctyp);
-
- -- Case of component size 1,2,4 or any component size for the modular
- -- case. These are the cases for which we can inline the code.
-
- if Csiz = 1 or else Csiz = 2 or else Csiz = 4
- or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
- then
- Setup_Inline_Packed_Array_Reference (Lhs, Atyp, Obj, Cmask, Shift);
-
- -- The statement to be generated is:
-
- -- Obj := atyp!((Obj and Mask1) or (shift_left (rhs, shift)))
-
- -- where mask1 is obtained by shifting Cmask left Shift bits
- -- and then complementing the result.
-
- -- the "and Mask1" is omitted if rhs is constant and all 1 bits
-
- -- the "or ..." is omitted if rhs is constant and all 0 bits
-
- -- rhs is converted to the appropriate type.
-
- -- The result is converted back to the array type, since
- -- otherwise we lose knowledge of the packed nature.
-
- -- Determine if right side is all 0 bits or all 1 bits
-
- if Compile_Time_Known_Value (Rhs) then
- Rhs_Val := Expr_Rep_Value (Rhs);
- Rhs_Val_Known := True;
-
- -- The following test catches the case of an unchecked conversion
- -- of an integer literal. This results from optimizing aggregates
- -- of packed types.
-
- elsif Nkind (Rhs) = N_Unchecked_Type_Conversion
- and then Compile_Time_Known_Value (Expression (Rhs))
- then
- Rhs_Val := Expr_Rep_Value (Expression (Rhs));
- Rhs_Val_Known := True;
-
- else
- Rhs_Val := No_Uint;
- Rhs_Val_Known := False;
- end if;
-
- -- Some special checks for the case where the right hand value
- -- is known at compile time. Basically we have to take care of
- -- the implicit conversion to the subtype of the component object.
-
- if Rhs_Val_Known then
-
- -- If we have a biased component type then we must manually do
- -- the biasing, since we are taking responsibility in this case
- -- for constructing the exact bit pattern to be used.
-
- if Has_Biased_Representation (Ctyp) then
- Rhs_Val := Rhs_Val - Expr_Rep_Value (Type_Low_Bound (Ctyp));
- end if;
-
- -- For a negative value, we manually convert the twos complement
- -- value to a corresponding unsigned value, so that the proper
- -- field width is maintained. If we did not do this, we would
- -- get too many leading sign bits later on.
-
- if Rhs_Val < 0 then
- Rhs_Val := 2 ** UI_From_Int (Csiz) + Rhs_Val;
- end if;
- end if;
-
- New_Lhs := Duplicate_Subexpr (Obj, True);
- New_Rhs := Duplicate_Subexpr (Obj);
-
- -- First we deal with the "and"
-
- if not Rhs_Val_Known or else Rhs_Val /= Cmask then
- declare
- Mask1 : Node_Id;
- Lit : Node_Id;
-
- begin
- if Compile_Time_Known_Value (Shift) then
- Mask1 :=
- Make_Integer_Literal (Loc,
- Modulus (Etype (Obj)) - 1 -
- (Cmask * (2 ** Expr_Value (Shift))));
- Set_Print_In_Hex (Mask1);
-
- else
- Lit := Make_Integer_Literal (Loc, Cmask);
- Set_Print_In_Hex (Lit);
- Mask1 :=
- Make_Op_Not (Loc,
- Right_Opnd => Make_Shift_Left (Lit, Shift));
- end if;
-
- New_Rhs :=
- Make_Op_And (Loc,
- Left_Opnd => New_Rhs,
- Right_Opnd => Mask1);
- end;
- end if;
-
- -- Then deal with the "or"
-
- if not Rhs_Val_Known or else Rhs_Val /= 0 then
- declare
- Or_Rhs : Node_Id;
-
- procedure Fixup_Rhs;
- -- Adjust Rhs by bias if biased representation for components
- -- or remove extraneous high order sign bits if signed.
-
- procedure Fixup_Rhs is
- Etyp : constant Entity_Id := Etype (Rhs);
-
- begin
- -- For biased case, do the required biasing by simply
- -- converting to the biased subtype (the conversion
- -- will generate the required bias).
-
- if Has_Biased_Representation (Ctyp) then
- Rhs := Convert_To (Ctyp, Rhs);
-
- -- For a signed integer type that is not biased, generate
- -- a conversion to unsigned to strip high order sign bits.
-
- elsif Is_Signed_Integer_Type (Ctyp) then
- Rhs := Unchecked_Convert_To (RTE (Bits_Id (Csiz)), Rhs);
- end if;
-
- -- Set Etype, since it can be referenced before the
- -- node is completely analyzed.
-
- Set_Etype (Rhs, Etyp);
-
- -- We now need to do an unchecked conversion of the
- -- result to the target type, but it is important that
- -- this conversion be a right justified conversion and
- -- not a left justified conversion.
-
- Rhs := RJ_Unchecked_Convert_To (Etype (Obj), Rhs);
-
- end Fixup_Rhs;
-
- begin
- if Rhs_Val_Known
- and then Compile_Time_Known_Value (Shift)
- then
- Or_Rhs :=
- Make_Integer_Literal (Loc,
- Rhs_Val * (2 ** Expr_Value (Shift)));
- Set_Print_In_Hex (Or_Rhs);
-
- else
- -- We have to convert the right hand side to Etype (Obj).
- -- A special case case arises if what we have now is a Val
- -- attribute reference whose expression type is Etype (Obj).
- -- This happens for assignments of fields from the same
- -- array. In this case we get the required right hand side
- -- by simply removing the inner attribute reference.
-
- if Nkind (Rhs) = N_Attribute_Reference
- and then Attribute_Name (Rhs) = Name_Val
- and then Etype (First (Expressions (Rhs))) = Etype (Obj)
- then
- Rhs := Relocate_Node (First (Expressions (Rhs)));
- Fixup_Rhs;
-
- -- If the value of the right hand side is a known integer
- -- value, then just replace it by an untyped constant,
- -- which will be properly retyped when we analyze and
- -- resolve the expression.
-
- elsif Rhs_Val_Known then
-
- -- Note that Rhs_Val has already been normalized to
- -- be an unsigned value with the proper number of bits.
-
- Rhs :=
- Make_Integer_Literal (Loc, Rhs_Val);
-
- -- Otherwise we need an unchecked conversion
-
- else
- Fixup_Rhs;
- end if;
-
- Or_Rhs := Make_Shift_Left (Rhs, Shift);
- end if;
-
- if Nkind (New_Rhs) = N_Op_And then
- Set_Paren_Count (New_Rhs, 1);
- end if;
-
- New_Rhs :=
- Make_Op_Or (Loc,
- Left_Opnd => New_Rhs,
- Right_Opnd => Or_Rhs);
- end;
- end if;
-
- -- Now do the rewrite
-
- Rewrite (N,
- Make_Assignment_Statement (Loc,
- Name => New_Lhs,
- Expression =>
- Unchecked_Convert_To (Etype (New_Lhs), New_Rhs)));
- Set_Assignment_OK (Name (N), Ass_OK);
-
- -- All other component sizes for non-modular case
-
- else
- -- We generate
-
- -- Set_nn (Arr'address, Subscr, Bits_nn!(Rhs))
-
- -- where Subscr is the computed linear subscript.
-
- declare
- Bits_nn : constant Entity_Id := RTE (Bits_Id (Csiz));
- Set_nn : Entity_Id;
- Subscr : Node_Id;
- Atyp : Entity_Id;
-
- begin
- -- Acquire proper Set entity. We use the aligned or unaligned
- -- case as appropriate.
-
- if Known_Aligned_Enough (Obj, Csiz) then
- Set_nn := RTE (Set_Id (Csiz));
- else
- Set_nn := RTE (SetU_Id (Csiz));
- end if;
-
- -- Now generate the set reference
-
- Obj := Relocate_Node (Prefix (Lhs));
- Convert_To_Actual_Subtype (Obj);
- Atyp := Etype (Obj);
- Compute_Linear_Subscript (Atyp, Lhs, Subscr);
-
- Rewrite (N,
- Make_Procedure_Call_Statement (Loc,
- Name => New_Occurrence_Of (Set_nn, Loc),
- Parameter_Associations => New_List (
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => Obj),
- Subscr,
- Unchecked_Convert_To (Bits_nn,
- Convert_To (Ctyp, Rhs)))));
-
- end;
- end if;
-
- Analyze (N, Suppress => All_Checks);
- end Expand_Bit_Packed_Element_Set;
-
- -------------------------------------
- -- Expand_Packed_Address_Reference --
- -------------------------------------
-
- procedure Expand_Packed_Address_Reference (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Ploc : Source_Ptr;
- Pref : Node_Id;
- Expr : Node_Id;
- Term : Node_Id;
- Atyp : Entity_Id;
- Subscr : Node_Id;
-
- begin
- Pref := Prefix (N);
- Expr := Empty;
-
- -- We build up an expression serially that has the form
-
- -- outer_object'Address
- -- + (linear-subscript * component_size for each array reference
- -- + field'Bit_Position for each record field
- -- + ...
- -- + ...) / Storage_Unit;
-
- -- Some additional conversions are required to deal with the addition
- -- operation, which is not normally visible to generated code.
-
- loop
- Ploc := Sloc (Pref);
-
- if Nkind (Pref) = N_Indexed_Component then
- Convert_To_Actual_Subtype (Prefix (Pref));
- Atyp := Etype (Prefix (Pref));
- Compute_Linear_Subscript (Atyp, Pref, Subscr);
-
- Term :=
- Make_Op_Multiply (Ploc,
- Left_Opnd => Subscr,
- Right_Opnd =>
- Make_Attribute_Reference (Ploc,
- Prefix => New_Occurrence_Of (Atyp, Ploc),
- Attribute_Name => Name_Component_Size));
-
- elsif Nkind (Pref) = N_Selected_Component then
- Term :=
- Make_Attribute_Reference (Ploc,
- Prefix => Selector_Name (Pref),
- Attribute_Name => Name_Bit_Position);
-
- else
- exit;
- end if;
-
- Term := Convert_To (RTE (RE_Integer_Address), Term);
-
- if No (Expr) then
- Expr := Term;
-
- else
- Expr :=
- Make_Op_Add (Ploc,
- Left_Opnd => Expr,
- Right_Opnd => Term);
- end if;
-
- Pref := Prefix (Pref);
- end loop;
-
- Rewrite (N,
- Unchecked_Convert_To (RTE (RE_Address),
- Make_Op_Add (Loc,
- Left_Opnd =>
- Unchecked_Convert_To (RTE (RE_Integer_Address),
- Make_Attribute_Reference (Loc,
- Prefix => Pref,
- Attribute_Name => Name_Address)),
-
- Right_Opnd =>
- Make_Op_Divide (Loc,
- Left_Opnd => Expr,
- Right_Opnd =>
- Make_Integer_Literal (Loc, System_Storage_Unit)))));
-
- Analyze_And_Resolve (N, RTE (RE_Address));
- end Expand_Packed_Address_Reference;
-
- ------------------------------------
- -- Expand_Packed_Boolean_Operator --
- ------------------------------------
-
- -- This routine expands "a op b" for the packed cases
-
- procedure Expand_Packed_Boolean_Operator (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Typ : constant Entity_Id := Etype (N);
- L : constant Node_Id := Relocate_Node (Left_Opnd (N));
- R : constant Node_Id := Relocate_Node (Right_Opnd (N));
-
- Ltyp : Entity_Id;
- Rtyp : Entity_Id;
- PAT : Entity_Id;
-
- begin
- Convert_To_Actual_Subtype (L);
- Convert_To_Actual_Subtype (R);
-
- Ensure_Defined (Etype (L), N);
- Ensure_Defined (Etype (R), N);
-
- Apply_Length_Check (R, Etype (L));
-
- Ltyp := Etype (L);
- Rtyp := Etype (R);
-
- -- First an odd and silly test. We explicitly check for the XOR
- -- case where the component type is True .. True, since this will
- -- raise constraint error. A special check is required since CE
- -- will not be required other wise (cf Expand_Packed_Not).
-
- -- No such check is required for AND and OR, since for both these
- -- cases False op False = False, and True op True = True.
-
- if Nkind (N) = N_Op_Xor then
- declare
- CT : constant Entity_Id := Component_Type (Rtyp);
- BT : constant Entity_Id := Base_Type (CT);
-
- begin
- Insert_Action (N,
- Make_Raise_Constraint_Error (Loc,
- Condition =>
- Make_Op_And (Loc,
- Left_Opnd =>
- Make_Op_Eq (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (CT, Loc),
- Attribute_Name => Name_First),
-
- Right_Opnd =>
- Convert_To (BT,
- New_Occurrence_Of (Standard_True, Loc))),
-
- Right_Opnd =>
- Make_Op_Eq (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (CT, Loc),
- Attribute_Name => Name_Last),
-
- Right_Opnd =>
- Convert_To (BT,
- New_Occurrence_Of (Standard_True, Loc))))));
- end;
- end if;
-
- -- Now that that silliness is taken care of, get packed array type
-
- Convert_To_PAT_Type (L);
- Convert_To_PAT_Type (R);
-
- PAT := Etype (L);
-
- -- For the modular case, we expand a op b into
-
- -- rtyp!(pat!(a) op pat!(b))
-
- -- where rtyp is the Etype of the left operand. Note that we do not
- -- convert to the base type, since this would be unconstrained, and
- -- hence not have a corresponding packed array type set.
-
- if Is_Modular_Integer_Type (PAT) then
- declare
- P : Node_Id;
-
- begin
- if Nkind (N) = N_Op_And then
- P := Make_Op_And (Loc, L, R);
-
- elsif Nkind (N) = N_Op_Or then
- P := Make_Op_Or (Loc, L, R);
-
- else -- Nkind (N) = N_Op_Xor
- P := Make_Op_Xor (Loc, L, R);
- end if;
-
- Rewrite (N, Unchecked_Convert_To (Rtyp, P));
- end;
-
- -- For the array case, we insert the actions
-
- -- Result : Ltype;
-
- -- System.Bitops.Bit_And/Or/Xor
- -- (Left'Address,
- -- Ltype'Length * Ltype'Component_Size;
- -- Right'Address,
- -- Rtype'Length * Rtype'Component_Size
- -- Result'Address);
-
- -- where Left and Right are the Packed_Bytes{1,2,4} operands and
- -- the second argument and fourth arguments are the lengths of the
- -- operands in bits. Then we replace the expression by a reference
- -- to Result.
-
- else
- declare
- Result_Ent : constant Entity_Id :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('T'));
-
- E_Id : RE_Id;
-
- begin
- if Nkind (N) = N_Op_And then
- E_Id := RE_Bit_And;
-
- elsif Nkind (N) = N_Op_Or then
- E_Id := RE_Bit_Or;
-
- else -- Nkind (N) = N_Op_Xor
- E_Id := RE_Bit_Xor;
- end if;
-
- Insert_Actions (N, New_List (
-
- Make_Object_Declaration (Loc,
- Defining_Identifier => Result_Ent,
- Object_Definition => New_Occurrence_Of (Ltyp, Loc)),
-
- Make_Procedure_Call_Statement (Loc,
- Name => New_Occurrence_Of (RTE (E_Id), Loc),
- Parameter_Associations => New_List (
-
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => L),
-
- Make_Op_Multiply (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of
- (Etype (First_Index (Ltyp)), Loc),
- Attribute_Name => Name_Range_Length),
- Right_Opnd =>
- Make_Integer_Literal (Loc, Component_Size (Ltyp))),
-
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => R),
-
- Make_Op_Multiply (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of
- (Etype (First_Index (Rtyp)), Loc),
- Attribute_Name => Name_Range_Length),
- Right_Opnd =>
- Make_Integer_Literal (Loc, Component_Size (Rtyp))),
-
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => New_Occurrence_Of (Result_Ent, Loc))))));
-
- Rewrite (N,
- New_Occurrence_Of (Result_Ent, Loc));
- end;
- end if;
-
- Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
- end Expand_Packed_Boolean_Operator;
-
- -------------------------------------
- -- Expand_Packed_Element_Reference --
- -------------------------------------
-
- procedure Expand_Packed_Element_Reference (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Obj : Node_Id;
- Atyp : Entity_Id;
- PAT : Entity_Id;
- Ctyp : Entity_Id;
- Csiz : Int;
- Shift : Node_Id;
- Cmask : Uint;
- Lit : Node_Id;
- Arg : Node_Id;
-
- begin
- -- If not bit packed, we have the enumeration case, which is easily
- -- dealt with (just adjust the subscripts of the indexed component)
-
- -- Note: this leaves the result as an indexed component, which is
- -- still a variable, so can be used in the assignment case, as is
- -- required in the enumeration case.
-
- if not Is_Bit_Packed_Array (Etype (Prefix (N))) then
- Setup_Enumeration_Packed_Array_Reference (N);
- return;
- end if;
-
- -- Remaining processing is for the bit-packed case.
-
- Obj := Relocate_Node (Prefix (N));
- Convert_To_Actual_Subtype (Obj);
- Atyp := Etype (Obj);
- PAT := Packed_Array_Type (Atyp);
- Ctyp := Component_Type (Atyp);
- Csiz := UI_To_Int (Component_Size (Atyp));
-
- -- Case of component size 1,2,4 or any component size for the modular
- -- case. These are the cases for which we can inline the code.
-
- if Csiz = 1 or else Csiz = 2 or else Csiz = 4
- or else (Present (PAT) and then Is_Modular_Integer_Type (PAT))
- then
- Setup_Inline_Packed_Array_Reference (N, Atyp, Obj, Cmask, Shift);
- Lit := Make_Integer_Literal (Loc, Cmask);
- Set_Print_In_Hex (Lit);
-
- -- We generate a shift right to position the field, followed by a
- -- masking operation to extract the bit field, and we finally do an
- -- unchecked conversion to convert the result to the required target.
-
- -- Note that the unchecked conversion automatically deals with the
- -- bias if we are dealing with a biased representation. What will
- -- happen is that we temporarily generate the biased representation,
- -- but almost immediately that will be converted to the original
- -- unbiased component type, and the bias will disappear.
-
- Arg :=
- Make_Op_And (Loc,
- Left_Opnd => Make_Shift_Right (Obj, Shift),
- Right_Opnd => Lit);
-
- Analyze_And_Resolve (Arg);
-
- Rewrite (N,
- RJ_Unchecked_Convert_To (Ctyp, Arg));
-
- -- All other component sizes for non-modular case
-
- else
- -- We generate
-
- -- Component_Type!(Get_nn (Arr'address, Subscr))
-
- -- where Subscr is the computed linear subscript.
-
- declare
- Get_nn : Entity_Id;
- Subscr : Node_Id;
-
- begin
- -- Acquire proper Get entity. We use the aligned or unaligned
- -- case as appropriate.
-
- if Known_Aligned_Enough (Obj, Csiz) then
- Get_nn := RTE (Get_Id (Csiz));
- else
- Get_nn := RTE (GetU_Id (Csiz));
- end if;
-
- -- Now generate the get reference
-
- Compute_Linear_Subscript (Atyp, N, Subscr);
-
- Rewrite (N,
- Unchecked_Convert_To (Ctyp,
- Make_Function_Call (Loc,
- Name => New_Occurrence_Of (Get_nn, Loc),
- Parameter_Associations => New_List (
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => Obj),
- Subscr))));
- end;
- end if;
-
- Analyze_And_Resolve (N, Ctyp, Suppress => All_Checks);
-
- end Expand_Packed_Element_Reference;
-
- ----------------------
- -- Expand_Packed_Eq --
- ----------------------
-
- -- Handles expansion of "=" on packed array types
-
- procedure Expand_Packed_Eq (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- L : constant Node_Id := Relocate_Node (Left_Opnd (N));
- R : constant Node_Id := Relocate_Node (Right_Opnd (N));
-
- LLexpr : Node_Id;
- RLexpr : Node_Id;
-
- Ltyp : Entity_Id;
- Rtyp : Entity_Id;
- PAT : Entity_Id;
-
- begin
- Convert_To_Actual_Subtype (L);
- Convert_To_Actual_Subtype (R);
- Ltyp := Underlying_Type (Etype (L));
- Rtyp := Underlying_Type (Etype (R));
-
- Convert_To_PAT_Type (L);
- Convert_To_PAT_Type (R);
- PAT := Etype (L);
-
- LLexpr :=
- Make_Op_Multiply (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Length,
- Prefix => New_Occurrence_Of (Ltyp, Loc)),
- Right_Opnd =>
- Make_Integer_Literal (Loc, Component_Size (Ltyp)));
-
- RLexpr :=
- Make_Op_Multiply (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Length,
- Prefix => New_Occurrence_Of (Rtyp, Loc)),
- Right_Opnd =>
- Make_Integer_Literal (Loc, Component_Size (Rtyp)));
-
- -- For the modular case, we transform the comparison to:
-
- -- Ltyp'Length = Rtyp'Length and then PAT!(L) = PAT!(R)
-
- -- where PAT is the packed array type. This works fine, since in the
- -- modular case we guarantee that the unused bits are always zeroes.
- -- We do have to compare the lengths because we could be comparing
- -- two different subtypes of the same base type.
-
- if Is_Modular_Integer_Type (PAT) then
- Rewrite (N,
- Make_And_Then (Loc,
- Left_Opnd =>
- Make_Op_Eq (Loc,
- Left_Opnd => LLexpr,
- Right_Opnd => RLexpr),
-
- Right_Opnd =>
- Make_Op_Eq (Loc,
- Left_Opnd => L,
- Right_Opnd => R)));
-
- -- For the non-modular case, we call a runtime routine
-
- -- System.Bit_Ops.Bit_Eq
- -- (L'Address, L_Length, R'Address, R_Length)
-
- -- where PAT is the packed array type, and the lengths are the lengths
- -- in bits of the original packed arrays. This routine takes care of
- -- not comparing the unused bits in the last byte.
-
- else
- Rewrite (N,
- Make_Function_Call (Loc,
- Name => New_Occurrence_Of (RTE (RE_Bit_Eq), Loc),
- Parameter_Associations => New_List (
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => L),
-
- LLexpr,
-
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => R),
-
- RLexpr)));
- end if;
-
- Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks);
- end Expand_Packed_Eq;
-
- -----------------------
- -- Expand_Packed_Not --
- -----------------------
-
- -- Handles expansion of "not" on packed array types
-
- procedure Expand_Packed_Not (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Typ : constant Entity_Id := Etype (N);
- Opnd : constant Node_Id := Relocate_Node (Right_Opnd (N));
-
- Rtyp : Entity_Id;
- PAT : Entity_Id;
- Lit : Node_Id;
-
- begin
- Convert_To_Actual_Subtype (Opnd);
- Rtyp := Etype (Opnd);
-
- -- First an odd and silly test. We explicitly check for the case
- -- where the 'First of the component type is equal to the 'Last of
- -- this component type, and if this is the case, we make sure that
- -- constraint error is raised. The reason is that the NOT is bound
- -- to cause CE in this case, and we will not otherwise catch it.
-
- -- Believe it or not, this was reported as a bug. Note that nearly
- -- always, the test will evaluate statically to False, so the code
- -- will be statically removed, and no extra overhead caused.
-
- declare
- CT : constant Entity_Id := Component_Type (Rtyp);
-
- begin
- Insert_Action (N,
- Make_Raise_Constraint_Error (Loc,
- Condition =>
- Make_Op_Eq (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (CT, Loc),
- Attribute_Name => Name_First),
-
- Right_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (CT, Loc),
- Attribute_Name => Name_Last))));
- end;
-
- -- Now that that silliness is taken care of, get packed array type
-
- Convert_To_PAT_Type (Opnd);
- PAT := Etype (Opnd);
-
- -- For the case where the packed array type is a modular type,
- -- not A expands simply into:
-
- -- rtyp!(PAT!(A) xor mask)
-
- -- where PAT is the packed array type, and mask is a mask of all
- -- one bits of length equal to the size of this packed type and
- -- rtyp is the actual subtype of the operand
-
- Lit := Make_Integer_Literal (Loc, 2 ** Esize (PAT) - 1);
- Set_Print_In_Hex (Lit);
-
- if not Is_Array_Type (PAT) then
- Rewrite (N,
- Unchecked_Convert_To (Rtyp,
- Make_Op_Xor (Loc,
- Left_Opnd => Opnd,
- Right_Opnd => Lit)));
-
- -- For the array case, we insert the actions
-
- -- Result : Typ;
-
- -- System.Bitops.Bit_Not
- -- (Opnd'Address,
- -- Typ'Length * Typ'Component_Size;
- -- Result'Address);
-
- -- where Opnd is the Packed_Bytes{1,2,4} operand and the second
- -- argument is the length of the operand in bits. Then we replace
- -- the expression by a reference to Result.
-
- else
- declare
- Result_Ent : constant Entity_Id :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('T'));
-
- begin
- Insert_Actions (N, New_List (
-
- Make_Object_Declaration (Loc,
- Defining_Identifier => Result_Ent,
- Object_Definition => New_Occurrence_Of (Rtyp, Loc)),
-
- Make_Procedure_Call_Statement (Loc,
- Name => New_Occurrence_Of (RTE (RE_Bit_Not), Loc),
- Parameter_Associations => New_List (
-
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => Opnd),
-
- Make_Op_Multiply (Loc,
- Left_Opnd =>
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of
- (Etype (First_Index (Rtyp)), Loc),
- Attribute_Name => Name_Range_Length),
- Right_Opnd =>
- Make_Integer_Literal (Loc, Component_Size (Rtyp))),
-
- Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Address,
- Prefix => New_Occurrence_Of (Result_Ent, Loc))))));
-
- Rewrite (N,
- New_Occurrence_Of (Result_Ent, Loc));
- end;
- end if;
-
- Analyze_And_Resolve (N, Typ, Suppress => All_Checks);
-
- end Expand_Packed_Not;
-
- -------------------------------------
- -- Involves_Packed_Array_Reference --
- -------------------------------------
-
- function Involves_Packed_Array_Reference (N : Node_Id) return Boolean is
- begin
- if Nkind (N) = N_Indexed_Component
- and then Is_Bit_Packed_Array (Etype (Prefix (N)))
- then
- return True;
-
- elsif Nkind (N) = N_Selected_Component then
- return Involves_Packed_Array_Reference (Prefix (N));
-
- else
- return False;
- end if;
- end Involves_Packed_Array_Reference;
-
- --------------------------
- -- Known_Aligned_Enough --
- --------------------------
-
- function Known_Aligned_Enough (Obj : Node_Id; Csiz : Nat) return Boolean is
- Typ : constant Entity_Id := Etype (Obj);
-
- function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean;
- -- If the component is in a record that contains previous packed
- -- components, consider it unaligned because the back-end might
- -- choose to pack the rest of the record. Lead to less efficient code,
- -- but safer vis-a-vis of back-end choices.
-
- --------------------------------
- -- In_Partially_Packed_Record --
- --------------------------------
-
- function In_Partially_Packed_Record (Comp : Entity_Id) return Boolean is
- Rec_Type : constant Entity_Id := Scope (Comp);
- Prev_Comp : Entity_Id;
-
- begin
- Prev_Comp := First_Entity (Rec_Type);
- while Present (Prev_Comp) loop
- if Is_Packed (Etype (Prev_Comp)) then
- return True;
-
- elsif Prev_Comp = Comp then
- return False;
- end if;
-
- Next_Entity (Prev_Comp);
- end loop;
-
- return False;
- end In_Partially_Packed_Record;
-
- -- Start of processing for Known_Aligned_Enough
-
- begin
- -- Odd bit sizes don't need alignment anyway
-
- if Csiz mod 2 = 1 then
- return True;
-
- -- If we have a specified alignment, see if it is sufficient, if not
- -- then we can't possibly be aligned enough in any case.
-
- elsif Is_Entity_Name (Obj)
- and then Known_Alignment (Entity (Obj))
- then
- -- Alignment required is 4 if size is a multiple of 4, and
- -- 2 otherwise (e.g. 12 bits requires 4, 10 bits requires 2)
-
- if Alignment (Entity (Obj)) < 4 - (Csiz mod 4) then
- return False;
- end if;
- end if;
-
- -- OK, alignment should be sufficient, if object is aligned
-
- -- If object is strictly aligned, then it is definitely aligned
-
- if Strict_Alignment (Typ) then
- return True;
-
- -- Case of subscripted array reference
-
- elsif Nkind (Obj) = N_Indexed_Component then
-
- -- If we have a pointer to an array, then this is definitely
- -- aligned, because pointers always point to aligned versions.
-
- if Is_Access_Type (Etype (Prefix (Obj))) then
- return True;
-
- -- Otherwise, go look at the prefix
-
- else
- return Known_Aligned_Enough (Prefix (Obj), Csiz);
- end if;
-
- -- Case of record field
-
- elsif Nkind (Obj) = N_Selected_Component then
-
- -- What is significant here is whether the record type is packed
-
- if Is_Record_Type (Etype (Prefix (Obj)))
- and then Is_Packed (Etype (Prefix (Obj)))
- then
- return False;
-
- -- Or the component has a component clause which might cause
- -- the component to become unaligned (we can't tell if the
- -- backend is doing alignment computations).
-
- elsif Present (Component_Clause (Entity (Selector_Name (Obj)))) then
- return False;
-
- elsif In_Partially_Packed_Record (Entity (Selector_Name (Obj))) then
- return False;
-
- -- In all other cases, go look at prefix
-
- else
- return Known_Aligned_Enough (Prefix (Obj), Csiz);
- end if;
-
- -- If not selected or indexed component, must be aligned
-
- else
- return True;
- end if;
- end Known_Aligned_Enough;
-
- ---------------------
- -- Make_Shift_Left --
- ---------------------
-
- function Make_Shift_Left (N : Node_Id; S : Node_Id) return Node_Id is
- Nod : Node_Id;
-
- begin
- if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
- return N;
- else
- Nod :=
- Make_Op_Shift_Left (Sloc (N),
- Left_Opnd => N,
- Right_Opnd => S);
- Set_Shift_Count_OK (Nod, True);
- return Nod;
- end if;
- end Make_Shift_Left;
-
- ----------------------
- -- Make_Shift_Right --
- ----------------------
-
- function Make_Shift_Right (N : Node_Id; S : Node_Id) return Node_Id is
- Nod : Node_Id;
-
- begin
- if Compile_Time_Known_Value (S) and then Expr_Value (S) = 0 then
- return N;
- else
- Nod :=
- Make_Op_Shift_Right (Sloc (N),
- Left_Opnd => N,
- Right_Opnd => S);
- Set_Shift_Count_OK (Nod, True);
- return Nod;
- end if;
- end Make_Shift_Right;
-
- -----------------------------
- -- RJ_Unchecked_Convert_To --
- -----------------------------
-
- function RJ_Unchecked_Convert_To
- (Typ : Entity_Id;
- Expr : Node_Id)
- return Node_Id
- is
- Source_Typ : constant Entity_Id := Etype (Expr);
- Target_Typ : constant Entity_Id := Typ;
-
- Src : Node_Id := Expr;
-
- Source_Siz : Nat;
- Target_Siz : Nat;
-
- begin
- Source_Siz := UI_To_Int (RM_Size (Source_Typ));
- Target_Siz := UI_To_Int (RM_Size (Target_Typ));
-
- -- In the big endian case, if the lengths of the two types differ,
- -- then we must worry about possible left justification in the
- -- conversion, and avoiding that is what this is all about.
-
- if Bytes_Big_Endian and then Source_Siz /= Target_Siz then
-
- -- First step, if the source type is not a discrete type, then we
- -- first convert to a modular type of the source length, since
- -- otherwise, on a big-endian machine, we get left-justification.
-
- if not Is_Discrete_Type (Source_Typ) then
- Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src);
- end if;
-
- -- Next step. If the target is not a discrete type, then we first
- -- convert to a modular type of the target length, since
- -- otherwise, on a big-endian machine, we get left-justification.
-
- if not Is_Discrete_Type (Target_Typ) then
- Src := Unchecked_Convert_To (RTE (Bits_Id (Target_Siz)), Src);
- end if;
- end if;
-
- -- And now we can do the final conversion to the target type
-
- return Unchecked_Convert_To (Target_Typ, Src);
- end RJ_Unchecked_Convert_To;
-
- ----------------------------------------------
- -- Setup_Enumeration_Packed_Array_Reference --
- ----------------------------------------------
-
- -- All we have to do here is to find the subscripts that correspond
- -- to the index positions that have non-standard enumeration types
- -- and insert a Pos attribute to get the proper subscript value.
-
- -- Finally the prefix must be uncheck converted to the corresponding
- -- packed array type.
-
- -- Note that the component type is unchanged, so we do not need to
- -- fiddle with the types (Gigi always automatically takes the packed
- -- array type if it is set, as it will be in this case).
-
- procedure Setup_Enumeration_Packed_Array_Reference (N : Node_Id) is
- Pfx : constant Node_Id := Prefix (N);
- Typ : constant Entity_Id := Etype (N);
- Exprs : constant List_Id := Expressions (N);
- Expr : Node_Id;
-
- begin
- -- If the array is unconstrained, then we replace the array
- -- reference with its actual subtype. This actual subtype will
- -- have a packed array type with appropriate bounds.
-
- if not Is_Constrained (Packed_Array_Type (Etype (Pfx))) then
- Convert_To_Actual_Subtype (Pfx);
- end if;
-
- Expr := First (Exprs);
- while Present (Expr) loop
- declare
- Loc : constant Source_Ptr := Sloc (Expr);
- Expr_Typ : constant Entity_Id := Etype (Expr);
-
- begin
- if Is_Enumeration_Type (Expr_Typ)
- and then Has_Non_Standard_Rep (Expr_Typ)
- then
- Rewrite (Expr,
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Expr_Typ, Loc),
- Attribute_Name => Name_Pos,
- Expressions => New_List (Relocate_Node (Expr))));
- Analyze_And_Resolve (Expr, Standard_Natural);
- end if;
- end;
-
- Next (Expr);
- end loop;
-
- Rewrite (N,
- Make_Indexed_Component (Sloc (N),
- Prefix =>
- Unchecked_Convert_To (Packed_Array_Type (Etype (Pfx)), Pfx),
- Expressions => Exprs));
-
- Analyze_And_Resolve (N, Typ);
-
- end Setup_Enumeration_Packed_Array_Reference;
-
- -----------------------------------------
- -- Setup_Inline_Packed_Array_Reference --
- -----------------------------------------
-
- procedure Setup_Inline_Packed_Array_Reference
- (N : Node_Id;
- Atyp : Entity_Id;
- Obj : in out Node_Id;
- Cmask : out Uint;
- Shift : out Node_Id)
- is
- Loc : constant Source_Ptr := Sloc (N);
- Ctyp : Entity_Id;
- PAT : Entity_Id;
- Otyp : Entity_Id;
- Csiz : Uint;
- Osiz : Uint;
-
- begin
- Ctyp := Component_Type (Atyp);
- Csiz := Component_Size (Atyp);
-
- Convert_To_PAT_Type (Obj);
- PAT := Etype (Obj);
-
- Cmask := 2 ** Csiz - 1;
-
- if Is_Array_Type (PAT) then
- Otyp := Component_Type (PAT);
- Osiz := Esize (Otyp);
-
- else
- Otyp := PAT;
-
- -- In the case where the PAT is a modular type, we want the actual
- -- size in bits of the modular value we use. This is neither the
- -- Object_Size nor the Value_Size, either of which may have been
- -- reset to strange values, but rather the minimum size. Note that
- -- since this is a modular type with full range, the issue of
- -- biased representation does not arise.
-
- Osiz := UI_From_Int (Minimum_Size (Otyp));
- end if;
-
- Compute_Linear_Subscript (Atyp, N, Shift);
-
- -- If the component size is not 1, then the subscript must be
- -- multiplied by the component size to get the shift count.
-
- if Csiz /= 1 then
- Shift :=
- Make_Op_Multiply (Loc,
- Left_Opnd => Make_Integer_Literal (Loc, Csiz),
- Right_Opnd => Shift);
- end if;
-
- -- If we have the array case, then this shift count must be broken
- -- down into a byte subscript, and a shift within the byte.
-
- if Is_Array_Type (PAT) then
-
- declare
- New_Shift : Node_Id;
-
- begin
- -- We must analyze shift, since we will duplicate it
-
- Set_Parent (Shift, N);
- Analyze_And_Resolve
- (Shift, Standard_Integer, Suppress => All_Checks);
-
- -- The shift count within the word is
- -- shift mod Osiz
-
- New_Shift :=
- Make_Op_Mod (Loc,
- Left_Opnd => Duplicate_Subexpr (Shift),
- Right_Opnd => Make_Integer_Literal (Loc, Osiz));
-
- -- The subscript to be used on the PAT array is
- -- shift / Osiz
-
- Obj :=
- Make_Indexed_Component (Loc,
- Prefix => Obj,
- Expressions => New_List (
- Make_Op_Divide (Loc,
- Left_Opnd => Duplicate_Subexpr (Shift),
- Right_Opnd => Make_Integer_Literal (Loc, Osiz))));
-
- Shift := New_Shift;
- end;
-
- -- For the modular integer case, the object to be manipulated is
- -- the entire array, so Obj is unchanged. Note that we will reset
- -- its type to PAT before returning to the caller.
-
- else
- null;
- end if;
-
- -- The one remaining step is to modify the shift count for the
- -- big-endian case. Consider the following example in a byte:
-
- -- xxxxxxxx bits of byte
- -- vvvvvvvv bits of value
- -- 33221100 little-endian numbering
- -- 00112233 big-endian numbering
-
- -- Here we have the case of 2-bit fields
-
- -- For the little-endian case, we already have the proper shift
- -- count set, e.g. for element 2, the shift count is 2*2 = 4.
-
- -- For the big endian case, we have to adjust the shift count,
- -- computing it as (N - F) - shift, where N is the number of bits
- -- in an element of the array used to implement the packed array,
- -- F is the number of bits in a source level array element, and
- -- shift is the count so far computed.
-
- if Bytes_Big_Endian then
- Shift :=
- Make_Op_Subtract (Loc,
- Left_Opnd => Make_Integer_Literal (Loc, Osiz - Csiz),
- Right_Opnd => Shift);
- end if;
-
- Set_Parent (Shift, N);
- Set_Parent (Obj, N);
- Analyze_And_Resolve (Obj, Otyp, Suppress => All_Checks);
- Analyze_And_Resolve (Shift, Standard_Integer, Suppress => All_Checks);
-
- -- Make sure final type of object is the appropriate packed type
-
- Set_Etype (Obj, Otyp);
-
- end Setup_Inline_Packed_Array_Reference;
-
-end Exp_Pakd;
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