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| author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
|---|---|---|
| committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
| commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
| tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /gcc/ada/exp_pakd.adb | |
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Diffstat (limited to 'gcc/ada/exp_pakd.adb')
| -rw-r--r-- | gcc/ada/exp_pakd.adb | 2744 |
1 files changed, 2744 insertions, 0 deletions
diff --git a/gcc/ada/exp_pakd.adb b/gcc/ada/exp_pakd.adb new file mode 100644 index 000000000..4d3ea0688 --- /dev/null +++ b/gcc/ada/exp_pakd.adb @@ -0,0 +1,2744 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- E X P _ P A K D -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2010, 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 3, 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 COPYING3. If not, go to -- +-- http://www.gnu.org/licenses for a complete copy of the license. -- +-- -- +-- 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 Errout; use Errout; +with Exp_Dbug; use Exp_Dbug; +with Exp_Util; use Exp_Util; +with Layout; use Layout; +with Namet; use Namet; +with Nlists; use Nlists; +with Nmake; use Nmake; +with Opt; use Opt; +with Rtsfind; use Rtsfind; +with Sem; use Sem; +with Sem_Aux; use Sem_Aux; +with Sem_Ch3; use Sem_Ch3; +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 machine + -- 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 provides 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 : constant 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 : constant 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. + + procedure Get_Base_And_Bit_Offset + (N : Node_Id; + Base : out Node_Id; + Offset : out Node_Id); + -- Given a node N for a name which involves a packed array reference, + -- return the base object of the reference and build an expression of + -- type Standard.Integer representing the zero-based offset in bits + -- from Base'Address to the first bit of the reference. + + 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, Long_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_Subscript -- + ------------------------------ + + 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 : Node_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. + + -- This is not strictly the case ??? If the reference is an actual in + -- call, the expansion of the prefix is delayed, and must be reanalyzed, + -- see Reset_Packed_Prefix. On the other hand, if the prefix is a simple + -- array reference, reanalysis can produce spurious type errors when the + -- PAT type is replaced again with the original type of the array. Same + -- for the case of a dereference. The following is correct and minimal, + -- but the handling of more complex packed expressions in actuals is + -- confused. Probably the problem only remains for actuals in calls. + + Set_Etype (Aexp, Packed_Array_Type (Act_ST)); + + if Is_Entity_Name (Aexp) + or else + (Nkind (Aexp) = N_Indexed_Component + and then Is_Entity_Name (Prefix (Aexp))) + or else Nkind (Aexp) = N_Explicit_Dereference + then + Set_Analyzed (Aexp); + end if; + 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; + PASize : 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 + Push_Scope (Scope (Typ)); + Pushed_Scope := True; + end if; + + Set_Is_Itype (PAT, True); + Set_Packed_Array_Type (Typ, PAT); + 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. + + if Unknown_Esize (PAT) then + Set_Esize (PAT, PASize); + end if; + + if Unknown_RM_Size (PAT) then + Set_RM_Size (PAT, PASize); + end if; + + Adjust_Esize_Alignment (PAT); + + -- Set remaining fields of packed array type + + Init_Alignment (PAT); + Set_Parent (PAT, Empty); + Set_Associated_Node_For_Itype (PAT, Typ); + Set_Is_Packed_Array_Type (PAT, True); + Set_Original_Array_Type (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); + + -- If we did allocate a freeze node, then clear out the reference + -- since it is obsolete (should we delete the freeze node???) + + Set_Freeze_Node (PAT, Empty); + Set_Freeze_Node (Etype (PAT), Empty); + end Install_PAT; + + ----------------- + -- Set_PB_Type -- + ----------------- + + procedure Set_PB_Type is + begin + -- If the user has specified an explicit alignment for the + -- type or component, take it into account. + + if Csize <= 2 or else Csize = 4 or else Csize mod 2 /= 0 + or else Alignment (Typ) = 1 + or else Component_Alignment (Typ) = Calign_Storage_Unit + then + PB_Type := RTE (RE_Packed_Bytes1); + + elsif Csize mod 4 /= 0 + or else Alignment (Typ) = 2 + 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 the ancestor is not an array type but + -- a private type, as can happen with multiple instantiations, create + -- a new packed type, to avoid privacy issues. + + if Ekind (Typ) = E_Array_Subtype then + Ancest := Ancestor_Subtype (Typ); + + if Present (Ancest) + and then Is_Array_Type (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. + + PASize := RM_Size (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 : constant 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, + Component_Definition => + Make_Component_Definition (Loc, + Aliased_Present => False, + Subtype_Indication => + New_Occurrence_Of (Ctyp, Loc))); + + else + Typedef := + Make_Constrained_Array_Definition (Loc, + Discrete_Subtype_Definitions => Indexes, + Component_Definition => + Make_Component_Definition (Loc, + Aliased_Present => False, + Subtype_Indication => + New_Occurrence_Of (Ctyp, Loc))); + end if; + + Decl := + Make_Full_Type_Declaration (Loc, + Defining_Identifier => PAT, + Type_Definition => Typedef); + end; + + -- Set type as packed array type and install it + + Set_Is_Packed_Array_Type (PAT); + Install_PAT; + return; + + -- Case of bit-packing required for unconstrained array. We create + -- a subtype that is equivalent to use Packed_Bytes{1,2,4} as needed. + + elsif not Is_Constrained (Typ) then + PAT := + Make_Defining_Identifier (Loc, + Chars => Make_Packed_Array_Type_Name (Typ, Csize)); + + Set_Packed_Array_Type (Typ, PAT); + Set_PB_Type; + + Decl := + Make_Subtype_Declaration (Loc, + Defining_Identifier => PAT, + Subtype_Indication => New_Occurrence_Of (PB_Type, Loc)); + Install_PAT; + 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. This expression may involve + -- discriminants, so we treat it as a default/per-object expression. + + Set_Parent (Len_Expr, Typ); + Preanalyze_Spec_Expression (Len_Expr, Standard_Long_Long_Integer); + + -- Use a modular type if possible. We can do this if 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 anomalous size. + + if Compile_Time_Known_Value (Len_Expr) then + Len_Bits := Expr_Value (Len_Expr) * Csize; + + -- Check for size known to be too large + + if Len_Bits > + Uint_2 ** (Standard_Integer_Size - 1) * System_Storage_Unit + then + if System_Storage_Unit = 8 then + Error_Msg_N + ("packed array size cannot exceed " & + "Integer''Last bytes", Typ); + else + Error_Msg_N + ("packed array size cannot exceed " & + "Integer''Last storage units", Typ); + end if; + + -- Reset length to arbitrary not too high value to continue + + Len_Expr := Make_Integer_Literal (Loc, 65535); + Analyze_And_Resolve (Len_Expr, Standard_Long_Long_Integer); + end if; + + -- We normally consider small enough to mean no larger than the + -- value of System_Max_Binary_Modulus_Power, checking that in the + -- case of values longer than word size, we have long shifts. + + if Len_Bits > 0 + and then + (Len_Bits <= System_Word_Size + or else (Len_Bits <= System_Max_Binary_Modulus_Power + and then Support_Long_Shifts_On_Target)) + then + -- We can use the modular type, it has the form: + + -- subtype tttPn is btyp + -- range 0 .. 2 ** ((Typ'Length (1) + -- * ... * Typ'Length (n)) * Csize) - 1; + + -- The bounds are statically known, and btyp is one of the + -- unsigned types, depending on the length. + + if Len_Bits <= Standard_Short_Short_Integer_Size then + Btyp := RTE (RE_Short_Short_Unsigned); + + elsif Len_Bits <= Standard_Short_Integer_Size then + Btyp := RTE (RE_Short_Unsigned); + + elsif Len_Bits <= Standard_Integer_Size then + Btyp := RTE (RE_Unsigned); + + elsif Len_Bits <= Standard_Long_Integer_Size then + Btyp := RTE (RE_Long_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 PASize = Uint_0 then + PASize := Len_Bits; + end if; + + Install_PAT; + + -- Propagate a given alignment to the modular type. This can + -- cause it to be under-aligned, but that's OK. + + if Present (Alignment_Clause (Typ)) then + Set_Alignment (PAT, Alignment (Typ)); + end if; + + 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 => + Convert_To (Standard_Integer, PAT_High)))))); + + Install_PAT; + + -- Currently the code in this unit requires that packed arrays + -- represented by non-modular arrays of bytes be on a byte + -- boundary for bit sizes handled by System.Pack_nn units. + -- That's because these units assume the array being accessed + -- starts on a byte boundary. + + if Get_Id (UI_To_Int (Csize)) /= RE_Null then + Set_Must_Be_On_Byte_Boundary (Typ); + end if; + 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; + Cmask : Uint; + + Shift : Node_Id; + -- The expression for the shift value that is required + + Shift_Used : Boolean := False; + -- Set True if Shift has been used in the generated code at least + -- once, so that it must be duplicated if used again + + 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. + + function Get_Shift return Node_Id; + -- Function used to get the value of Shift, making sure that it + -- gets duplicated if the function is called more than once. + + --------------- + -- Get_Shift -- + --------------- + + function Get_Shift return Node_Id is + begin + -- If we used the shift value already, then duplicate it. We + -- set a temporary parent in case actions have to be inserted. + + if Shift_Used then + Set_Parent (Shift, N); + return Duplicate_Subexpr_No_Checks (Shift); + + -- If first time, use Shift unchanged, and set flag for first use + + else + Shift_Used := True; + return Shift; + end if; + end Get_Shift; + + -- Start of processing for Expand_Bit_Packed_Element_Set + + 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 remove side effects, in case the rhs modifies the lhs, because we + -- are about to transform the rhs into an expression that first READS + -- the lhs, so we can do the necessary shifting and masking. Example: + -- "X(2) := F(...);" where F modifies X(3). Otherwise, the side effect + -- will be lost. + + Remove_Side_Effects (Rhs); + + -- 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) + + -- If the right-hand side is a string literal, create a temporary for + -- it, constant-folding is not ready to wrap the bit representation + -- of a string literal. + + if Nkind (Rhs) = N_String_Literal then + declare + Decl : Node_Id; + begin + Decl := + Make_Object_Declaration (Loc, + Defining_Identifier => Make_Temporary (Loc, 'T', Rhs), + Object_Definition => New_Occurrence_Of (Ctyp, Loc), + Expression => New_Copy_Tree (Rhs)); + + Insert_Actions (N, New_List (Decl)); + Rhs := New_Occurrence_Of (Defining_Identifier (Decl), Loc); + end; + end if; + + Rhs := Convert_To (Ctyp, Rhs); + Set_Parent (Rhs, N); + + -- If we are building the initialization procedure for a packed array, + -- and Initialize_Scalars is enabled, each component assignment is an + -- out-of-range value by design. Compile this value without checks, + -- because a call to the array init_proc must not raise an exception. + + if Within_Init_Proc + and then Initialize_Scalars + then + Analyze_And_Resolve (Rhs, Ctyp, Suppress => All_Checks); + else + Analyze_And_Resolve (Rhs, Ctyp); + end if; + + -- For the AAMP target, indexing of certain packed array is passed + -- through to the back end without expansion, because the expansion + -- results in very inefficient code on that target. This allows the + -- GNAAMP back end to generate specialized macros that support more + -- efficient indexing of packed arrays with components having sizes + -- that are small powers of two. + + if AAMP_On_Target + and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4) + then + return; + end if; + + -- 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 two's 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; + + -- Now create copies removing side effects. Note that in some + -- complex cases, this may cause the fact that we have already + -- set a packed array type on Obj to get lost. So we save the + -- type of Obj, and make sure it is reset properly. + + declare + T : constant Entity_Id := Etype (Obj); + begin + New_Lhs := Duplicate_Subexpr (Obj, True); + New_Rhs := Duplicate_Subexpr_No_Checks (Obj); + Set_Etype (Obj, T); + Set_Etype (New_Lhs, T); + Set_Etype (New_Rhs, T); + end; + + -- 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 (Get_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, Get_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 (Get_Shift) + then + Or_Rhs := + Make_Integer_Literal (Loc, + Rhs_Val * (2 ** Expr_Value (Get_Shift))); + Set_Print_In_Hex (Or_Rhs); + + else + -- We have to convert the right hand side to Etype (Obj). + -- A special 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, Get_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 + if No (Bits_nn) then + + -- Error, most likely High_Integrity_Mode restriction + + return; + end if; + + -- 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); + + -- Below we must make the assumption that Obj is + -- at least byte aligned, since otherwise its address + -- cannot be taken. The assumption holds since the + -- only arrays that can be misaligned are small packed + -- arrays which are implemented as a modular type, and + -- that is not the case here. + + Rewrite (N, + Make_Procedure_Call_Statement (Loc, + Name => New_Occurrence_Of (Set_nn, Loc), + Parameter_Associations => New_List ( + Make_Attribute_Reference (Loc, + Prefix => Obj, + Attribute_Name => Name_Address), + 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); + Base : Node_Id; + Offset : Node_Id; + + begin + -- We build an expression that has the form + + -- outer_object'Address + -- + (linear-subscript * component_size for each array reference + -- + field'Bit_Position for each record field + -- + ... + -- + ...) / Storage_Unit; + + Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); + + 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 => Base, + Attribute_Name => Name_Address)), + + Right_Opnd => + Unchecked_Convert_To (RTE (RE_Integer_Address), + Make_Op_Divide (Loc, + Left_Opnd => Offset, + Right_Opnd => + Make_Integer_Literal (Loc, System_Storage_Unit)))))); + + Analyze_And_Resolve (N, RTE (RE_Address)); + end Expand_Packed_Address_Reference; + + --------------------------------- + -- Expand_Packed_Bit_Reference -- + --------------------------------- + + procedure Expand_Packed_Bit_Reference (N : Node_Id) is + Loc : constant Source_Ptr := Sloc (N); + Base : Node_Id; + Offset : Node_Id; + + begin + -- We build an expression that has the form + + -- (linear-subscript * component_size for each array reference + -- + field'Bit_Position for each record field + -- + ... + -- + ...) mod Storage_Unit; + + Get_Base_And_Bit_Offset (Prefix (N), Base, Offset); + + Rewrite (N, + Unchecked_Convert_To (Universal_Integer, + Make_Op_Mod (Loc, + Left_Opnd => Offset, + Right_Opnd => Make_Integer_Literal (Loc, System_Storage_Unit)))); + + Analyze_And_Resolve (N, Universal_Integer); + end Expand_Packed_Bit_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); + + -- Deal with silly case of XOR where the subcomponent has a range + -- True .. True where an exception must be raised. + + if Nkind (N) = N_Op_Xor then + Silly_Boolean_Array_Xor_Test (N, Rtyp); + 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. + + -- Note that both operands must be modular for this code to be used + + if Is_Modular_Integer_Type (PAT) + and then + Is_Modular_Integer_Type (Etype (R)) + 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 (Ltyp, P)); + end; + + -- For the array case, we insert the actions + + -- Result : Ltype; + + -- System.Bit_Ops.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. + + -- Note that if we are mixing a modular and array operand, everything + -- works fine, since we ensure that the modular representation has the + -- same physical layout as the array representation (that's what the + -- left justified modular stuff in the big-endian case is about). + + else + declare + Result_Ent : constant Entity_Id := Make_Temporary (Loc, '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_Byte_Aligned_Attribute_Reference (Loc, + Prefix => L, + Attribute_Name => Name_Address), + + 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_Byte_Aligned_Attribute_Reference (Loc, + Prefix => R, + Attribute_Name => Name_Address), + + 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_Byte_Aligned_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of (Result_Ent, Loc), + Attribute_Name => Name_Address))))); + + 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)); + + -- For the AAMP target, indexing of certain packed array is passed + -- through to the back end without expansion, because the expansion + -- results in very inefficient code on that target. This allows the + -- GNAAMP back end to generate specialized macros that support more + -- efficient indexing of packed arrays with components having sizes + -- that are small powers of two. + + if AAMP_On_Target + and then (Csiz = 1 or else Csiz = 2 or else Csiz = 4) + then + return; + end if; + + -- 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); + + -- We needed to analyze this before we do the unchecked convert + -- below, but we need it temporarily attached to the tree for + -- this analysis (hence the temporary Set_Parent call). + + Set_Parent (Arg, Parent (N)); + 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); + + -- Below we make the assumption that Obj is at least byte + -- aligned, since otherwise its address cannot be taken. + -- The assumption holds since the only arrays that can be + -- misaligned are small packed arrays which are implemented + -- as a modular type, and that is not the case here. + + 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, + Prefix => Obj, + Attribute_Name => Name_Address), + 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, + Prefix => New_Occurrence_Of (Ltyp, Loc), + Attribute_Name => Name_Length), + Right_Opnd => + Make_Integer_Literal (Loc, Component_Size (Ltyp))); + + RLexpr := + Make_Op_Multiply (Loc, + Left_Opnd => + Make_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of (Rtyp, Loc), + Attribute_Name => Name_Length), + 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_Byte_Aligned_Attribute_Reference (Loc, + Prefix => L, + Attribute_Name => Name_Address), + + LLexpr, + + Make_Byte_Aligned_Attribute_Reference (Loc, + Prefix => R, + Attribute_Name => Name_Address), + + 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); + + -- Deal with silly False..False and True..True subtype case + + Silly_Boolean_Array_Not_Test (N, Rtyp); + + -- Now that the 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, Mask is a mask of all 1 bits of + -- length equal to the size of this packed type, and Rtyp is the actual + -- actual subtype of the operand. + + Lit := Make_Integer_Literal (Loc, 2 ** RM_Size (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.Bit_Ops.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. We then replace the expression + -- with a reference to Result. + + else + declare + Result_Ent : constant Entity_Id := Make_Temporary (Loc, '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_Byte_Aligned_Attribute_Reference (Loc, + Prefix => Opnd, + Attribute_Name => Name_Address), + + 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_Byte_Aligned_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of (Result_Ent, Loc), + Attribute_Name => Name_Address))))); + + Rewrite (N, New_Occurrence_Of (Result_Ent, Loc)); + end; + end if; + + Analyze_And_Resolve (N, Typ, Suppress => All_Checks); + end Expand_Packed_Not; + + ----------------------------- + -- Get_Base_And_Bit_Offset -- + ----------------------------- + + procedure Get_Base_And_Bit_Offset + (N : Node_Id; + Base : out Node_Id; + Offset : out Node_Id) + is + Loc : Source_Ptr; + Term : Node_Id; + Atyp : Entity_Id; + Subscr : Node_Id; + + begin + Base := N; + Offset := Empty; + + -- We build up an expression serially that has the form + + -- linear-subscript * component_size for each array reference + -- + field'Bit_Position for each record field + -- + ... + + loop + Loc := Sloc (Base); + + if Nkind (Base) = N_Indexed_Component then + Convert_To_Actual_Subtype (Prefix (Base)); + Atyp := Etype (Prefix (Base)); + Compute_Linear_Subscript (Atyp, Base, Subscr); + + Term := + Make_Op_Multiply (Loc, + Left_Opnd => Subscr, + Right_Opnd => + Make_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of (Atyp, Loc), + Attribute_Name => Name_Component_Size)); + + elsif Nkind (Base) = N_Selected_Component then + Term := + Make_Attribute_Reference (Loc, + Prefix => Selector_Name (Base), + Attribute_Name => Name_Bit_Position); + + else + return; + end if; + + if No (Offset) then + Offset := Term; + + else + Offset := + Make_Op_Add (Loc, + Left_Opnd => Offset, + Right_Opnd => Term); + end if; + + Base := Prefix (Base); + end loop; + end Get_Base_And_Bit_Offset; + + ------------------------------------- + -- 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 Known_Alignment (Etype (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 (Etype (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; + + elsif Nkind (Obj) = N_Type_Conversion then + return Known_Aligned_Enough (Expression (Obj), Csiz); + + -- For a formal parameter, it is safer to assume that it is not + -- aligned, because the formal may be unconstrained while the actual + -- is constrained. In this situation, a small constrained packed + -- array, represented in modular form, may be unaligned. + + elsif Is_Entity_Name (Obj) then + return not Is_Formal (Entity (Obj)); + else + + -- If none of the above, must be aligned + 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)); + + -- 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. We do it for little- + -- endian machines as well, because there might be junk bits that are + -- not cleared if the type is not numeric. + + if Source_Siz /= Target_Siz + and then not Is_Discrete_Type (Source_Typ) + then + Src := Unchecked_Convert_To (RTE (Bits_Id (Source_Siz)), Src); + end if; + + -- 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 + + -- 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); + PAT : Entity_Id; + Otyp : Entity_Id; + Csiz : Uint; + Osiz : Uint; + + begin + 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 := Component_Size (PAT); + + 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 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; |