+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- L A Y O U T --
--- --
--- B o d y --
--- --
--- $Revision: 1.6.10.1 $
--- --
--- Copyright (C) 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 Debug; use Debug;
-with Einfo; use Einfo;
-with Errout; use Errout;
-with Exp_Ch3; use Exp_Ch3;
-with Exp_Util; use Exp_Util;
-with Nlists; use Nlists;
-with Nmake; use Nmake;
-with Repinfo; use Repinfo;
-with Sem; use Sem;
-with Sem_Ch13; use Sem_Ch13;
-with Sem_Eval; use Sem_Eval;
-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 Layout is
-
- ------------------------
- -- Local Declarations --
- ------------------------
-
- SSU : constant Int := Ttypes.System_Storage_Unit;
- -- Short hand for System_Storage_Unit
-
- Vname : constant Name_Id := Name_uV;
- -- Formal parameter name used for functions generated for size offset
- -- values that depend on the discriminant. All such functions have the
- -- following form:
- --
- -- function xxx (V : vtyp) return Unsigned is
- -- begin
- -- return ... expression involving V.discrim
- -- end xxx;
-
- -----------------------
- -- Local Subprograms --
- -----------------------
-
- procedure Adjust_Esize_Alignment (E : Entity_Id);
- -- E is the entity for a type or object. This procedure checks that the
- -- size and alignment are compatible, and if not either gives an error
- -- message if they cannot be adjusted or else adjusts them appropriately.
-
- function Assoc_Add
- (Loc : Source_Ptr;
- Left_Opnd : Node_Id;
- Right_Opnd : Node_Id)
- return Node_Id;
- -- This is like Make_Op_Add except that it optimizes some cases knowing
- -- that associative rearrangement is allowed for constant folding if one
- -- of the operands is a compile time known value.
-
- function Assoc_Multiply
- (Loc : Source_Ptr;
- Left_Opnd : Node_Id;
- Right_Opnd : Node_Id)
- return Node_Id;
- -- This is like Make_Op_Multiply except that it optimizes some cases
- -- knowing that associative rearrangement is allowed for constant
- -- folding if one of the operands is a compile time known value
-
- function Assoc_Subtract
- (Loc : Source_Ptr;
- Left_Opnd : Node_Id;
- Right_Opnd : Node_Id)
- return Node_Id;
- -- This is like Make_Op_Subtract except that it optimizes some cases
- -- knowing that associative rearrangement is allowed for constant
- -- folding if one of the operands is a compile time known value
-
- function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id;
- -- Given expressions for the low bound (Lo) and the high bound (Hi),
- -- Build an expression for the value hi-lo+1, converted to type
- -- Standard.Unsigned. Takes care of the case where the operands
- -- are of an enumeration type (so that the subtraction cannot be
- -- done directly) by applying the Pos operator to Hi/Lo first.
-
- function Expr_From_SO_Ref
- (Loc : Source_Ptr;
- D : SO_Ref)
- return Node_Id;
- -- Given a value D from a size or offset field, return an expression
- -- representing the value stored. If the value is known at compile time,
- -- then an N_Integer_Literal is returned with the appropriate value. If
- -- the value references a constant entity, then an N_Identifier node
- -- referencing this entity is returned. The Loc value is used for the
- -- Sloc value of constructed notes.
-
- function SO_Ref_From_Expr
- (Expr : Node_Id;
- Ins_Type : Entity_Id;
- Vtype : Entity_Id := Empty)
- return Dynamic_SO_Ref;
- -- This routine is used in the case where a size/offset value is dynamic
- -- and is represented by the expression Expr. SO_Ref_From_Expr checks if
- -- the Expr contains a reference to the identifier V, and if so builds
- -- a function depending on discriminants of the formal parameter V which
- -- is of type Vtype. If not, then a constant entity with the value Expr
- -- is built. The result is a Dynamic_SO_Ref to the created entity. Note
- -- that Vtype can be omitted if Expr does not contain any reference to V.
- -- the created entity. The declaration created is inserted in the freeze
- -- actions of Ins_Type, which also supplies the Sloc for created nodes.
- -- This function also takes care of making sure that the expression is
- -- properly analyzed and resolved (which may not be the case yet if we
- -- build the expression in this unit).
-
- function Get_Max_Size (E : Entity_Id) return Node_Id;
- -- E is an array type or subtype that has at least one index bound that
- -- is the value of a record discriminant. For such an array, the function
- -- computes an expression that yields the maximum possible size of the
- -- array in storage units. The result is not defined for any other type,
- -- or for arrays that do not depend on discriminants, and it is a fatal
- -- error to call this unless Size_Depends_On_Discrminant (E) is True.
-
- procedure Layout_Array_Type (E : Entity_Id);
- -- Front end layout of non-bit-packed array type or subtype
-
- procedure Layout_Record_Type (E : Entity_Id);
- -- Front end layout of record type
- -- Variant records not handled yet ???
-
- procedure Rewrite_Integer (N : Node_Id; V : Uint);
- -- Rewrite node N with an integer literal whose value is V. The Sloc
- -- for the new node is taken from N, and the type of the literal is
- -- set to a copy of the type of N on entry.
-
- procedure Set_And_Check_Static_Size
- (E : Entity_Id;
- Esiz : SO_Ref;
- RM_Siz : SO_Ref);
- -- This procedure is called to check explicit given sizes (possibly
- -- stored in the Esize and RM_Size fields of E) against computed
- -- Object_Size (Esiz) and Value_Size (RM_Siz) values. Appropriate
- -- errors and warnings are posted if specified sizes are inconsistent
- -- with specified sizes. On return, the Esize and RM_Size fields of
- -- E are set (either from previously given values, or from the newly
- -- computed values, as appropriate).
-
- ----------------------------
- -- Adjust_Esize_Alignment --
- ----------------------------
-
- procedure Adjust_Esize_Alignment (E : Entity_Id) is
- Abits : Int;
- Esize_Set : Boolean;
-
- begin
- -- Nothing to do if size unknown
-
- if Unknown_Esize (E) then
- return;
- end if;
-
- -- Determine if size is constrained by an attribute definition clause
- -- which must be obeyed. If so, we cannot increase the size in this
- -- routine.
-
- -- For a type, the issue is whether an object size clause has been
- -- set. A normal size clause constrains only the value size (RM_Size)
-
- if Is_Type (E) then
- Esize_Set := Has_Object_Size_Clause (E);
-
- -- For an object, the issue is whether a size clause is present
-
- else
- Esize_Set := Has_Size_Clause (E);
- end if;
-
- -- If size is known it must be a multiple of the byte size
-
- if Esize (E) mod SSU /= 0 then
-
- -- If not, and size specified, then give error
-
- if Esize_Set then
- Error_Msg_NE
- ("size for& not a multiple of byte size", Size_Clause (E), E);
- return;
-
- -- Otherwise bump up size to a byte boundary
-
- else
- Set_Esize (E, (Esize (E) + SSU - 1) / SSU * SSU);
- end if;
- end if;
-
- -- Now we have the size set, it must be a multiple of the alignment
- -- nothing more we can do here if the alignment is unknown here.
-
- if Unknown_Alignment (E) then
- return;
- end if;
-
- -- At this point both the Esize and Alignment are known, so we need
- -- to make sure they are consistent.
-
- Abits := UI_To_Int (Alignment (E)) * SSU;
-
- if Esize (E) mod Abits = 0 then
- return;
- end if;
-
- -- Here we have a situation where the Esize is not a multiple of
- -- the alignment. We must either increase Esize or reduce the
- -- alignment to correct this situation.
-
- -- The case in which we can decrease the alignment is where the
- -- alignment was not set by an alignment clause, and the type in
- -- question is a discrete type, where it is definitely safe to
- -- reduce the alignment. For example:
-
- -- t : integer range 1 .. 2;
- -- for t'size use 8;
-
- -- In this situation, the initial alignment of t is 4, copied from
- -- the Integer base type, but it is safe to reduce it to 1 at this
- -- stage, since we will only be loading a single byte.
-
- if Is_Discrete_Type (Etype (E))
- and then not Has_Alignment_Clause (E)
- then
- loop
- Abits := Abits / 2;
- exit when Esize (E) mod Abits = 0;
- end loop;
-
- Init_Alignment (E, Abits / SSU);
- return;
- end if;
-
- -- Now the only possible approach left is to increase the Esize
- -- but we can't do that if the size was set by a specific clause.
-
- if Esize_Set then
- Error_Msg_NE
- ("size for& is not a multiple of alignment",
- Size_Clause (E), E);
-
- -- Otherwise we can indeed increase the size to a multiple of alignment
-
- else
- Set_Esize (E, ((Esize (E) + (Abits - 1)) / Abits) * Abits);
- end if;
- end Adjust_Esize_Alignment;
-
- ---------------
- -- Assoc_Add --
- ---------------
-
- function Assoc_Add
- (Loc : Source_Ptr;
- Left_Opnd : Node_Id;
- Right_Opnd : Node_Id)
- return Node_Id
- is
- L : Node_Id;
- R : Uint;
-
- begin
- -- Case of right operand is a constant
-
- if Compile_Time_Known_Value (Right_Opnd) then
- L := Left_Opnd;
- R := Expr_Value (Right_Opnd);
-
- -- Case of left operand is a constant
-
- elsif Compile_Time_Known_Value (Left_Opnd) then
- L := Right_Opnd;
- R := Expr_Value (Left_Opnd);
-
- -- Neither operand is a constant, do the addition with no optimization
-
- else
- return Make_Op_Add (Loc, Left_Opnd, Right_Opnd);
- end if;
-
- -- Case of left operand is an addition
-
- if Nkind (L) = N_Op_Add then
-
- -- (C1 + E) + C2 = (C1 + C2) + E
-
- if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Left_Opnd (L),
- Expr_Value (Sinfo.Left_Opnd (L)) + R);
- return L;
-
- -- (E + C1) + C2 = E + (C1 + C2)
-
- elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Right_Opnd (L),
- Expr_Value (Sinfo.Right_Opnd (L)) + R);
- return L;
- end if;
-
- -- Case of left operand is a subtraction
-
- elsif Nkind (L) = N_Op_Subtract then
-
- -- (C1 - E) + C2 = (C1 + C2) + E
-
- if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Left_Opnd (L),
- Expr_Value (Sinfo.Left_Opnd (L)) + R);
- return L;
-
- -- (E - C1) + C2 = E - (C1 - C2)
-
- elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Right_Opnd (L),
- Expr_Value (Sinfo.Right_Opnd (L)) - R);
- return L;
- end if;
- end if;
-
- -- Not optimizable, do the addition
-
- return Make_Op_Add (Loc, Left_Opnd, Right_Opnd);
- end Assoc_Add;
-
- --------------------
- -- Assoc_Multiply --
- --------------------
-
- function Assoc_Multiply
- (Loc : Source_Ptr;
- Left_Opnd : Node_Id;
- Right_Opnd : Node_Id)
- return Node_Id
- is
- L : Node_Id;
- R : Uint;
-
- begin
- -- Case of right operand is a constant
-
- if Compile_Time_Known_Value (Right_Opnd) then
- L := Left_Opnd;
- R := Expr_Value (Right_Opnd);
-
- -- Case of left operand is a constant
-
- elsif Compile_Time_Known_Value (Left_Opnd) then
- L := Right_Opnd;
- R := Expr_Value (Left_Opnd);
-
- -- Neither operand is a constant, do the multiply with no optimization
-
- else
- return Make_Op_Multiply (Loc, Left_Opnd, Right_Opnd);
- end if;
-
- -- Case of left operand is an multiplication
-
- if Nkind (L) = N_Op_Multiply then
-
- -- (C1 * E) * C2 = (C1 * C2) + E
-
- if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Left_Opnd (L),
- Expr_Value (Sinfo.Left_Opnd (L)) * R);
- return L;
-
- -- (E * C1) * C2 = E * (C1 * C2)
-
- elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Right_Opnd (L),
- Expr_Value (Sinfo.Right_Opnd (L)) * R);
- return L;
- end if;
- end if;
-
- -- Not optimizable, do the multiplication
-
- return Make_Op_Multiply (Loc, Left_Opnd, Right_Opnd);
- end Assoc_Multiply;
-
- --------------------
- -- Assoc_Subtract --
- --------------------
-
- function Assoc_Subtract
- (Loc : Source_Ptr;
- Left_Opnd : Node_Id;
- Right_Opnd : Node_Id)
- return Node_Id
- is
- L : Node_Id;
- R : Uint;
-
- begin
- -- Case of right operand is a constant
-
- if Compile_Time_Known_Value (Right_Opnd) then
- L := Left_Opnd;
- R := Expr_Value (Right_Opnd);
-
- -- Right operand is a constant, do the subtract with no optimization
-
- else
- return Make_Op_Subtract (Loc, Left_Opnd, Right_Opnd);
- end if;
-
- -- Case of left operand is an addition
-
- if Nkind (L) = N_Op_Add then
-
- -- (C1 + E) - C2 = (C1 - C2) + E
-
- if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Left_Opnd (L),
- Expr_Value (Sinfo.Left_Opnd (L)) - R);
- return L;
-
- -- (E + C1) - C2 = E + (C1 - C2)
-
- elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Right_Opnd (L),
- Expr_Value (Sinfo.Right_Opnd (L)) - R);
- return L;
- end if;
-
- -- Case of left operand is a subtraction
-
- elsif Nkind (L) = N_Op_Subtract then
-
- -- (C1 - E) - C2 = (C1 - C2) + E
-
- if Compile_Time_Known_Value (Sinfo.Left_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Left_Opnd (L),
- Expr_Value (Sinfo.Left_Opnd (L)) + R);
- return L;
-
- -- (E - C1) - C2 = E - (C1 + C2)
-
- elsif Compile_Time_Known_Value (Sinfo.Right_Opnd (L)) then
- Rewrite_Integer
- (Sinfo.Right_Opnd (L),
- Expr_Value (Sinfo.Right_Opnd (L)) + R);
- return L;
- end if;
- end if;
-
- -- Not optimizable, do the subtraction
-
- return Make_Op_Subtract (Loc, Left_Opnd, Right_Opnd);
- end Assoc_Subtract;
-
- --------------------
- -- Compute_Length --
- --------------------
-
- function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id is
- Loc : constant Source_Ptr := Sloc (Lo);
- Typ : constant Entity_Id := Etype (Lo);
- Lo_Op : Node_Id;
- Hi_Op : Node_Id;
-
- begin
- Lo_Op := New_Copy_Tree (Lo);
- Hi_Op := New_Copy_Tree (Hi);
-
- -- If type is enumeration type, then use Pos attribute to convert
- -- to integer type for which subtraction is a permitted operation.
-
- if Is_Enumeration_Type (Typ) then
- Lo_Op :=
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Typ, Loc),
- Attribute_Name => Name_Pos,
- Expressions => New_List (Lo_Op));
-
- Hi_Op :=
- Make_Attribute_Reference (Loc,
- Prefix => New_Occurrence_Of (Typ, Loc),
- Attribute_Name => Name_Pos,
- Expressions => New_List (Hi_Op));
- end if;
-
- return
- Assoc_Add (Loc,
- Left_Opnd =>
- Assoc_Subtract (Loc,
- Left_Opnd => Hi_Op,
- Right_Opnd => Lo_Op),
- Right_Opnd => Make_Integer_Literal (Loc, 1));
- end Compute_Length;
-
- ----------------------
- -- Expr_From_SO_Ref --
- ----------------------
-
- function Expr_From_SO_Ref
- (Loc : Source_Ptr;
- D : SO_Ref)
- return Node_Id
- is
- Ent : Entity_Id;
-
- begin
- if Is_Dynamic_SO_Ref (D) then
- Ent := Get_Dynamic_SO_Entity (D);
-
- if Is_Discrim_SO_Function (Ent) then
- return
- Make_Function_Call (Loc,
- Name => New_Occurrence_Of (Ent, Loc),
- Parameter_Associations => New_List (
- Make_Identifier (Loc, Chars => Vname)));
-
- else
- return New_Occurrence_Of (Ent, Loc);
- end if;
-
- else
- return Make_Integer_Literal (Loc, D);
- end if;
- end Expr_From_SO_Ref;
-
- ------------------
- -- Get_Max_Size --
- ------------------
-
- function Get_Max_Size (E : Entity_Id) return Node_Id is
- Loc : constant Source_Ptr := Sloc (E);
- Indx : Node_Id;
- Ityp : Entity_Id;
- Lo : Node_Id;
- Hi : Node_Id;
- S : Uint;
- Len : Node_Id;
-
- type Val_Status_Type is (Const, Dynamic);
-
- type Val_Type (Status : Val_Status_Type := Const) is
- record
- case Status is
- when Const => Val : Uint;
- when Dynamic => Nod : Node_Id;
- end case;
- end record;
- -- Shows the status of the value so far. Const means that the value
- -- is constant, and Val is the current constant value. Dynamic means
- -- that the value is dynamic, and in this case Nod is the Node_Id of
- -- the expression to compute the value.
-
- Size : Val_Type;
- -- Calculated value so far if Size.Status = Const,
- -- or expression value so far if Size.Status = Dynamic.
-
- SU_Convert_Required : Boolean := False;
- -- This is set to True if the final result must be converted from
- -- bits to storage units (rounding up to a storage unit boundary).
-
- -----------------------
- -- Local Subprograms --
- -----------------------
-
- procedure Max_Discrim (N : in out Node_Id);
- -- If the node N represents a discriminant, replace it by the maximum
- -- value of the discriminant.
-
- procedure Min_Discrim (N : in out Node_Id);
- -- If the node N represents a discriminant, replace it by the minimum
- -- value of the discriminant.
-
- -----------------
- -- Max_Discrim --
- -----------------
-
- procedure Max_Discrim (N : in out Node_Id) is
- begin
- if Nkind (N) = N_Identifier
- and then Ekind (Entity (N)) = E_Discriminant
- then
- N := Type_High_Bound (Etype (N));
- end if;
- end Max_Discrim;
-
- -----------------
- -- Min_Discrim --
- -----------------
-
- procedure Min_Discrim (N : in out Node_Id) is
- begin
- if Nkind (N) = N_Identifier
- and then Ekind (Entity (N)) = E_Discriminant
- then
- N := Type_Low_Bound (Etype (N));
- end if;
- end Min_Discrim;
-
- -- Start of processing for Get_Max_Size
-
- begin
- pragma Assert (Size_Depends_On_Discriminant (E));
-
- -- Initialize status from component size
-
- if Known_Static_Component_Size (E) then
- Size := (Const, Component_Size (E));
-
- else
- Size := (Dynamic, Expr_From_SO_Ref (Loc, Component_Size (E)));
- end if;
-
- -- Loop through indices
-
- Indx := First_Index (E);
- while Present (Indx) loop
- Ityp := Etype (Indx);
- Lo := Type_Low_Bound (Ityp);
- Hi := Type_High_Bound (Ityp);
-
- Min_Discrim (Lo);
- Max_Discrim (Hi);
-
- -- Value of the current subscript range is statically known
-
- if Compile_Time_Known_Value (Lo)
- and then Compile_Time_Known_Value (Hi)
- then
- S := Expr_Value (Hi) - Expr_Value (Lo) + 1;
-
- -- If known flat bound, entire size of array is zero!
-
- if S <= 0 then
- return Make_Integer_Literal (Loc, 0);
- end if;
-
- -- Current value is constant, evolve value
-
- if Size.Status = Const then
- Size.Val := Size.Val * S;
-
- -- Current value is dynamic
-
- else
- -- An interesting little optimization, if we have a pending
- -- conversion from bits to storage units, and the current
- -- length is a multiple of the storage unit size, then we
- -- can take the factor out here statically, avoiding some
- -- extra dynamic computations at the end.
-
- if SU_Convert_Required and then S mod SSU = 0 then
- S := S / SSU;
- SU_Convert_Required := False;
- end if;
-
- Size.Nod :=
- Assoc_Multiply (Loc,
- Left_Opnd => Size.Nod,
- Right_Opnd =>
- Make_Integer_Literal (Loc, Intval => S));
- end if;
-
- -- Value of the current subscript range is dynamic
-
- else
- -- If the current size value is constant, then here is where we
- -- make a transition to dynamic values, which are always stored
- -- in storage units, However, we do not want to convert to SU's
- -- too soon, consider the case of a packed array of single bits,
- -- we want to do the SU conversion after computing the size in
- -- this case.
-
- if Size.Status = Const then
-
- -- If the current value is a multiple of the storage unit,
- -- then most certainly we can do the conversion now, simply
- -- by dividing the current value by the storage unit value.
- -- If this works, we set SU_Convert_Required to False.
-
- if Size.Val mod SSU = 0 then
-
- Size :=
- (Dynamic, Make_Integer_Literal (Loc, Size.Val / SSU));
- SU_Convert_Required := False;
-
- -- Otherwise, we go ahead and convert the value in bits,
- -- and set SU_Convert_Required to True to ensure that the
- -- final value is indeed properly converted.
-
- else
- Size := (Dynamic, Make_Integer_Literal (Loc, Size.Val));
- SU_Convert_Required := True;
- end if;
- end if;
-
- -- Length is hi-lo+1
-
- Len := Compute_Length (Lo, Hi);
-
- -- Check possible range of Len
-
- declare
- OK : Boolean;
- LLo : Uint;
- LHi : Uint;
-
- begin
- Set_Parent (Len, E);
- Determine_Range (Len, OK, LLo, LHi);
-
- Len := Convert_To (Standard_Unsigned, Len);
-
- -- If we cannot verify that range cannot be super-flat,
- -- we need a max with zero, since length must be non-neg.
-
- if not OK or else LLo < 0 then
- Len :=
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of (Standard_Unsigned, Loc),
- Attribute_Name => Name_Max,
- Expressions => New_List (
- Make_Integer_Literal (Loc, 0),
- Len));
- end if;
- end;
- end if;
-
- Next_Index (Indx);
- end loop;
-
- -- Here after processing all bounds to set sizes. If the value is
- -- a constant, then it is bits, and we just return the value.
-
- if Size.Status = Const then
- return Make_Integer_Literal (Loc, Size.Val);
-
- -- Case where the value is dynamic
-
- else
- -- Do convert from bits to SU's if needed
-
- if SU_Convert_Required then
-
- -- The expression required is (Size.Nod + SU - 1) / SU
-
- Size.Nod :=
- Make_Op_Divide (Loc,
- Left_Opnd =>
- Make_Op_Add (Loc,
- Left_Opnd => Size.Nod,
- Right_Opnd => Make_Integer_Literal (Loc, SSU - 1)),
- Right_Opnd => Make_Integer_Literal (Loc, SSU));
- end if;
-
- return Size.Nod;
- end if;
- end Get_Max_Size;
-
- -----------------------
- -- Layout_Array_Type --
- -----------------------
-
- procedure Layout_Array_Type (E : Entity_Id) is
- Loc : constant Source_Ptr := Sloc (E);
- Ctyp : constant Entity_Id := Component_Type (E);
- Indx : Node_Id;
- Ityp : Entity_Id;
- Lo : Node_Id;
- Hi : Node_Id;
- S : Uint;
- Len : Node_Id;
-
- Insert_Typ : Entity_Id;
- -- This is the type with which any generated constants or functions
- -- will be associated (i.e. inserted into the freeze actions). This
- -- is normally the type being layed out. The exception occurs when
- -- we are laying out Itype's which are local to a record type, and
- -- whose scope is this record type. Such types do not have freeze
- -- nodes (because we have no place to put them).
-
- ------------------------------------
- -- How An Array Type is Layed Out --
- ------------------------------------
-
- -- Here is what goes on. We need to multiply the component size of
- -- the array (which has already been set) by the length of each of
- -- the indexes. If all these values are known at compile time, then
- -- the resulting size of the array is the appropriate constant value.
-
- -- If the component size or at least one bound is dynamic (but no
- -- discriminants are present), then the size will be computed as an
- -- expression that calculates the proper size.
-
- -- If there is at least one discriminant bound, then the size is also
- -- computed as an expression, but this expression contains discriminant
- -- values which are obtained by selecting from a function parameter, and
- -- the size is given by a function that is passed the variant record in
- -- question, and whose body is the expression.
-
- type Val_Status_Type is (Const, Dynamic, Discrim);
-
- type Val_Type (Status : Val_Status_Type := Const) is
- record
- case Status is
- when Const =>
- Val : Uint;
- -- Calculated value so far if Val_Status = Const
-
- when Dynamic | Discrim =>
- Nod : Node_Id;
- -- Expression value so far if Val_Status /= Const
-
- end case;
- end record;
- -- Records the value or expression computed so far. Const means that
- -- the value is constant, and Val is the current constant value.
- -- Dynamic means that the value is dynamic, and in this case Nod is
- -- the Node_Id of the expression to compute the value, and Discrim
- -- means that at least one bound is a discriminant, in which case Nod
- -- is the expression so far (which will be the body of the function).
-
- Size : Val_Type;
- -- Value of size computed so far. See comments above.
-
- Vtyp : Entity_Id := Empty;
- -- Variant record type for the formal parameter of the
- -- discriminant function V if Status = Discrim.
-
- SU_Convert_Required : Boolean := False;
- -- This is set to True if the final result must be converted from
- -- bits to storage units (rounding up to a storage unit boundary).
-
- procedure Discrimify (N : in out Node_Id);
- -- If N represents a discriminant, then the Size.Status is set to
- -- Discrim, and Vtyp is set. The parameter N is replaced with the
- -- proper expression to extract the discriminant value from V.
-
- ----------------
- -- Discrimify --
- ----------------
-
- procedure Discrimify (N : in out Node_Id) is
- Decl : Node_Id;
- Typ : Entity_Id;
-
- begin
- if Nkind (N) = N_Identifier
- and then Ekind (Entity (N)) = E_Discriminant
- then
- Set_Size_Depends_On_Discriminant (E);
-
- if Size.Status /= Discrim then
- Decl := Parent (Parent (Entity (N)));
- Size := (Discrim, Size.Nod);
- Vtyp := Defining_Identifier (Decl);
- end if;
-
- Typ := Etype (N);
-
- N :=
- Make_Selected_Component (Loc,
- Prefix => Make_Identifier (Loc, Chars => Vname),
- Selector_Name => New_Occurrence_Of (Entity (N), Loc));
-
- -- Set the Etype attributes of the selected name and its prefix.
- -- Analyze_And_Resolve can't be called here because the Vname
- -- entity denoted by the prefix will not yet exist (it's created
- -- by SO_Ref_From_Expr, called at the end of Layout_Array_Type).
-
- Set_Etype (Prefix (N), Vtyp);
- Set_Etype (N, Typ);
- end if;
- end Discrimify;
-
- -- Start of processing for Layout_Array_Type
-
- begin
- -- Default alignment is component alignment
-
- if Unknown_Alignment (E) then
- Set_Alignment (E, Alignment (Ctyp));
- end if;
-
- -- Calculate proper type for insertions
-
- if Is_Record_Type (Scope (E)) then
- Insert_Typ := Scope (E);
- else
- Insert_Typ := E;
- end if;
-
- -- Cannot do anything if Esize of component type unknown
-
- if Unknown_Esize (Ctyp) then
- return;
- end if;
-
- -- Set component size if not set already
-
- if Unknown_Component_Size (E) then
- Set_Component_Size (E, Esize (Ctyp));
- end if;
-
- -- (RM 13.3 (48)) says that the size of an unconstrained array
- -- is implementation defined. We choose to leave it as Unknown
- -- here, and the actual behavior is determined by the back end.
-
- if not Is_Constrained (E) then
- return;
- end if;
-
- -- Initialize status from component size
-
- if Known_Static_Component_Size (E) then
- Size := (Const, Component_Size (E));
-
- else
- Size := (Dynamic, Expr_From_SO_Ref (Loc, Component_Size (E)));
- end if;
-
- -- Loop to process array indices
-
- Indx := First_Index (E);
- while Present (Indx) loop
- Ityp := Etype (Indx);
- Lo := Type_Low_Bound (Ityp);
- Hi := Type_High_Bound (Ityp);
-
- -- Value of the current subscript range is statically known
-
- if Compile_Time_Known_Value (Lo)
- and then Compile_Time_Known_Value (Hi)
- then
- S := Expr_Value (Hi) - Expr_Value (Lo) + 1;
-
- -- If known flat bound, entire size of array is zero!
-
- if S <= 0 then
- Set_Esize (E, Uint_0);
- Set_RM_Size (E, Uint_0);
- return;
- end if;
-
- -- If constant, evolve value
-
- if Size.Status = Const then
- Size.Val := Size.Val * S;
-
- -- Current value is dynamic
-
- else
- -- An interesting little optimization, if we have a pending
- -- conversion from bits to storage units, and the current
- -- length is a multiple of the storage unit size, then we
- -- can take the factor out here statically, avoiding some
- -- extra dynamic computations at the end.
-
- if SU_Convert_Required and then S mod SSU = 0 then
- S := S / SSU;
- SU_Convert_Required := False;
- end if;
-
- -- Now go ahead and evolve the expression
-
- Size.Nod :=
- Assoc_Multiply (Loc,
- Left_Opnd => Size.Nod,
- Right_Opnd =>
- Make_Integer_Literal (Loc, Intval => S));
- end if;
-
- -- Value of the current subscript range is dynamic
-
- else
- -- If the current size value is constant, then here is where we
- -- make a transition to dynamic values, which are always stored
- -- in storage units, However, we do not want to convert to SU's
- -- too soon, consider the case of a packed array of single bits,
- -- we want to do the SU conversion after computing the size in
- -- this case.
-
- if Size.Status = Const then
-
- -- If the current value is a multiple of the storage unit,
- -- then most certainly we can do the conversion now, simply
- -- by dividing the current value by the storage unit value.
- -- If this works, we set SU_Convert_Required to False.
-
- if Size.Val mod SSU = 0 then
- Size :=
- (Dynamic, Make_Integer_Literal (Loc, Size.Val / SSU));
- SU_Convert_Required := False;
-
- -- Otherwise, we go ahead and convert the value in bits,
- -- and set SU_Convert_Required to True to ensure that the
- -- final value is indeed properly converted.
-
- else
- Size := (Dynamic, Make_Integer_Literal (Loc, Size.Val));
- SU_Convert_Required := True;
- end if;
- end if;
-
- Discrimify (Lo);
- Discrimify (Hi);
-
- -- Length is hi-lo+1
-
- Len := Compute_Length (Lo, Hi);
-
- -- Check possible range of Len
-
- declare
- OK : Boolean;
- LLo : Uint;
- LHi : Uint;
-
- begin
- Set_Parent (Len, E);
- Determine_Range (Len, OK, LLo, LHi);
-
- Len := Convert_To (Standard_Unsigned, Len);
-
- -- If range definitely flat or superflat, result size is zero
-
- if OK and then LHi <= 0 then
- Set_Esize (E, Uint_0);
- Set_RM_Size (E, Uint_0);
- return;
- end if;
-
- -- If we cannot verify that range cannot be super-flat, we
- -- need a maximum with zero, since length cannot be negative.
-
- if not OK or else LLo < 0 then
- Len :=
- Make_Attribute_Reference (Loc,
- Prefix =>
- New_Occurrence_Of (Standard_Unsigned, Loc),
- Attribute_Name => Name_Max,
- Expressions => New_List (
- Make_Integer_Literal (Loc, 0),
- Len));
- end if;
- end;
-
- -- At this stage, Len has the expression for the length
-
- Size.Nod :=
- Assoc_Multiply (Loc,
- Left_Opnd => Size.Nod,
- Right_Opnd => Len);
- end if;
-
- Next_Index (Indx);
- end loop;
-
- -- Here after processing all bounds to set sizes. If the value is
- -- a constant, then it is bits, and the only thing we need to do
- -- is to check against explicit given size and do alignment adjust.
-
- if Size.Status = Const then
- Set_And_Check_Static_Size (E, Size.Val, Size.Val);
- Adjust_Esize_Alignment (E);
-
- -- Case where the value is dynamic
-
- else
- -- Do convert from bits to SU's if needed
-
- if SU_Convert_Required then
-
- -- The expression required is (Size.Nod + SU - 1) / SU
-
- Size.Nod :=
- Make_Op_Divide (Loc,
- Left_Opnd =>
- Make_Op_Add (Loc,
- Left_Opnd => Size.Nod,
- Right_Opnd => Make_Integer_Literal (Loc, SSU - 1)),
- Right_Opnd => Make_Integer_Literal (Loc, SSU));
- end if;
-
- -- Now set the dynamic size (the Value_Size is always the same
- -- as the Object_Size for arrays whose length is dynamic).
-
- -- ??? If Size.Status = Dynamic, Vtyp will not have been set.
- -- The added initialization sets it to Empty now, but is this
- -- correct?
-
- Set_Esize (E, SO_Ref_From_Expr (Size.Nod, Insert_Typ, Vtyp));
- Set_RM_Size (E, Esize (E));
- end if;
- end Layout_Array_Type;
-
- -------------------
- -- Layout_Object --
- -------------------
-
- procedure Layout_Object (E : Entity_Id) is
- T : constant Entity_Id := Etype (E);
-
- begin
- -- Nothing to do if backend does layout
-
- if not Frontend_Layout_On_Target then
- return;
- end if;
-
- -- Set size if not set for object and known for type. Use the
- -- RM_Size if that is known for the type and Esize is not.
-
- if Unknown_Esize (E) then
- if Known_Esize (T) then
- Set_Esize (E, Esize (T));
-
- elsif Known_RM_Size (T) then
- Set_Esize (E, RM_Size (T));
- end if;
- end if;
-
- -- Set alignment from type if unknown and type alignment known
-
- if Unknown_Alignment (E) and then Known_Alignment (T) then
- Set_Alignment (E, Alignment (T));
- end if;
-
- -- Make sure size and alignment are consistent
-
- Adjust_Esize_Alignment (E);
-
- -- Final adjustment, if we don't know the alignment, and the Esize
- -- was not set by an explicit Object_Size attribute clause, then
- -- we reset the Esize to unknown, since we really don't know it.
-
- if Unknown_Alignment (E)
- and then not Has_Size_Clause (E)
- then
- Set_Esize (E, Uint_0);
- end if;
- end Layout_Object;
-
- ------------------------
- -- Layout_Record_Type --
- ------------------------
-
- procedure Layout_Record_Type (E : Entity_Id) is
- Loc : constant Source_Ptr := Sloc (E);
- Decl : Node_Id;
-
- Comp : Entity_Id;
- -- Current component being layed out
-
- Prev_Comp : Entity_Id;
- -- Previous layed out component
-
- procedure Get_Next_Component_Location
- (Prev_Comp : Entity_Id;
- Align : Uint;
- New_Npos : out SO_Ref;
- New_Fbit : out SO_Ref;
- New_NPMax : out SO_Ref;
- Force_SU : Boolean);
- -- Given the previous component in Prev_Comp, which is already laid
- -- out, and the alignment of the following component, lays out the
- -- following component, and returns its starting position in New_Npos
- -- (Normalized_Position value), New_Fbit (Normalized_First_Bit value),
- -- and New_NPMax (Normalized_Position_Max value). If Prev_Comp is empty
- -- (no previous component is present), then New_Npos, New_Fbit and
- -- New_NPMax are all set to zero on return. This procedure is also
- -- used to compute the size of a record or variant by giving it the
- -- last component, and the record alignment. Force_SU is used to force
- -- the new component location to be aligned on a storage unit boundary,
- -- even in a packed record, False means that the new position does not
- -- need to be bumped to a storage unit boundary, True means a storage
- -- unit boundary is always required.
-
- procedure Layout_Component (Comp : Entity_Id; Prev_Comp : Entity_Id);
- -- Lays out component Comp, given Prev_Comp, the previously laid-out
- -- component (Prev_Comp = Empty if no components laid out yet). The
- -- alignment of the record itself is also updated if needed. Both
- -- Comp and Prev_Comp can be either components or discriminants. A
- -- special case is when Comp is Empty, this is used at the end
- -- to determine the size of the entire record. For this special
- -- call the resulting offset is placed in Final_Offset.
-
- procedure Layout_Components
- (From : Entity_Id;
- To : Entity_Id;
- Esiz : out SO_Ref;
- RM_Siz : out SO_Ref);
- -- This procedure lays out the components of the given component list
- -- which contains the components starting with From, and ending with To.
- -- The Next_Entity chain is used to traverse the components. On entry
- -- Prev_Comp is set to the component preceding the list, so that the
- -- list is layed out after this component. Prev_Comp is set to Empty if
- -- the component list is to be layed out starting at the start of the
- -- record. On return, the components are all layed out, and Prev_Comp is
- -- set to the last layed out component. On return, Esiz is set to the
- -- resulting Object_Size value, which is the length of the record up
- -- to and including the last layed out entity. For Esiz, the value is
- -- adjusted to match the alignment of the record. RM_Siz is similarly
- -- set to the resulting Value_Size value, which is the same length, but
- -- not adjusted to meet the alignment. Note that in the case of variant
- -- records, Esiz represents the maximum size.
-
- procedure Layout_Non_Variant_Record;
- -- Procedure called to layout a non-variant record type or subtype
-
- procedure Layout_Variant_Record;
- -- Procedure called to layout a variant record type. Decl is set to the
- -- full type declaration for the variant record.
-
- ---------------------------------
- -- Get_Next_Component_Location --
- ---------------------------------
-
- procedure Get_Next_Component_Location
- (Prev_Comp : Entity_Id;
- Align : Uint;
- New_Npos : out SO_Ref;
- New_Fbit : out SO_Ref;
- New_NPMax : out SO_Ref;
- Force_SU : Boolean)
- is
- begin
- -- No previous component, return zero position
-
- if No (Prev_Comp) then
- New_Npos := Uint_0;
- New_Fbit := Uint_0;
- New_NPMax := Uint_0;
- return;
- end if;
-
- -- Here we have a previous component
-
- declare
- Loc : constant Source_Ptr := Sloc (Prev_Comp);
-
- Old_Npos : constant SO_Ref := Normalized_Position (Prev_Comp);
- Old_Fbit : constant SO_Ref := Normalized_First_Bit (Prev_Comp);
- Old_NPMax : constant SO_Ref := Normalized_Position_Max (Prev_Comp);
- Old_Esiz : constant SO_Ref := Esize (Prev_Comp);
-
- Old_Maxsz : Node_Id;
- -- Expression representing maximum size of previous component
-
- begin
- -- Case where previous field had a dynamic size
-
- if Is_Dynamic_SO_Ref (Esize (Prev_Comp)) then
-
- -- If the previous field had a dynamic length, then it is
- -- required to occupy an integral number of storage units,
- -- and start on a storage unit boundary. This means that
- -- the Normalized_First_Bit value is zero in the previous
- -- component, and the new value is also set to zero.
-
- New_Fbit := Uint_0;
-
- -- In this case, the new position is given by an expression
- -- that is the sum of old normalized position and old size.
-
- New_Npos :=
- SO_Ref_From_Expr
- (Assoc_Add (Loc,
- Left_Opnd => Expr_From_SO_Ref (Loc, Old_Npos),
- Right_Opnd => Expr_From_SO_Ref (Loc, Old_Esiz)),
- Ins_Type => E,
- Vtype => E);
-
- -- Get maximum size of previous component
-
- if Size_Depends_On_Discriminant (Etype (Prev_Comp)) then
- Old_Maxsz := Get_Max_Size (Etype (Prev_Comp));
- else
- Old_Maxsz := Expr_From_SO_Ref (Loc, Old_Esiz);
- end if;
-
- -- Now we can compute the new max position. If the max size
- -- is static and the old position is static, then we can
- -- compute the new position statically.
-
- if Nkind (Old_Maxsz) = N_Integer_Literal
- and then Known_Static_Normalized_Position_Max (Prev_Comp)
- then
- New_NPMax := Old_NPMax + Intval (Old_Maxsz);
-
- -- Otherwise new max position is dynamic
-
- else
- New_NPMax :=
- SO_Ref_From_Expr
- (Assoc_Add (Loc,
- Left_Opnd => Expr_From_SO_Ref (Loc, Old_NPMax),
- Right_Opnd => Old_Maxsz),
- Ins_Type => E,
- Vtype => E);
- end if;
-
- -- Previous field has known static Esize
-
- else
- New_Fbit := Old_Fbit + Old_Esiz;
-
- -- Bump New_Fbit to storage unit boundary if required
-
- if New_Fbit /= 0 and then Force_SU then
- New_Fbit := (New_Fbit + SSU - 1) / SSU * SSU;
- end if;
-
- -- If old normalized position is static, we can go ahead
- -- and compute the new normalized position directly.
-
- if Known_Static_Normalized_Position (Prev_Comp) then
- New_Npos := Old_Npos;
-
- if New_Fbit >= SSU then
- New_Npos := New_Npos + New_Fbit / SSU;
- New_Fbit := New_Fbit mod SSU;
- end if;
-
- -- Bump alignment if stricter than prev
-
- if Align > Alignment (Prev_Comp) then
- New_Npos := (New_Npos + Align - 1) / Align * Align;
- end if;
-
- -- The max position is always equal to the position if
- -- the latter is static, since arrays depending on the
- -- values of discriminants never have static sizes.
-
- New_NPMax := New_Npos;
- return;
-
- -- Case of old normalized position is dynamic
-
- else
- -- If new bit position is within the current storage unit,
- -- we can just copy the old position as the result position
- -- (we have already set the new first bit value).
-
- if New_Fbit < SSU then
- New_Npos := Old_Npos;
- New_NPMax := Old_NPMax;
-
- -- If new bit position is past the current storage unit, we
- -- need to generate a new dynamic value for the position
- -- ??? need to deal with alignment
-
- else
- New_Npos :=
- SO_Ref_From_Expr
- (Assoc_Add (Loc,
- Left_Opnd => Expr_From_SO_Ref (Loc, Old_Npos),
- Right_Opnd =>
- Make_Integer_Literal (Loc,
- Intval => New_Fbit / SSU)),
- Ins_Type => E,
- Vtype => E);
-
- New_NPMax :=
- SO_Ref_From_Expr
- (Assoc_Add (Loc,
- Left_Opnd => Expr_From_SO_Ref (Loc, Old_NPMax),
- Right_Opnd =>
- Make_Integer_Literal (Loc,
- Intval => New_Fbit / SSU)),
- Ins_Type => E,
- Vtype => E);
- New_Fbit := New_Fbit mod SSU;
- end if;
- end if;
- end if;
- end;
- end Get_Next_Component_Location;
-
- ----------------------
- -- Layout_Component --
- ----------------------
-
- procedure Layout_Component (Comp : Entity_Id; Prev_Comp : Entity_Id) is
- Ctyp : constant Entity_Id := Etype (Comp);
- Npos : SO_Ref;
- Fbit : SO_Ref;
- NPMax : SO_Ref;
- Forc : Boolean;
-
- begin
- -- Parent field is always at start of record, this will overlap
- -- the actual fields that are part of the parent, and that's fine
-
- if Chars (Comp) = Name_uParent then
- Set_Normalized_Position (Comp, Uint_0);
- Set_Normalized_First_Bit (Comp, Uint_0);
- Set_Normalized_Position_Max (Comp, Uint_0);
- Set_Component_Bit_Offset (Comp, Uint_0);
- Set_Esize (Comp, Esize (Ctyp));
- return;
- end if;
-
- -- Check case of type of component has a scope of the record we
- -- are laying out. When this happens, the type in question is an
- -- Itype that has not yet been layed out (that's because such
- -- types do not get frozen in the normal manner, because there
- -- is no place for the freeze nodes).
-
- if Scope (Ctyp) = E then
- Layout_Type (Ctyp);
- end if;
-
- -- Increase alignment of record if necessary. Note that we do not
- -- do this for packed records, which have an alignment of one by
- -- default, or for records for which an explicit alignment was
- -- specified with an alignment clause.
-
- if not Is_Packed (E)
- and then not Has_Alignment_Clause (E)
- and then Alignment (Ctyp) > Alignment (E)
- then
- Set_Alignment (E, Alignment (Ctyp));
- end if;
-
- -- If component already laid out, then we are done
-
- if Known_Normalized_Position (Comp) then
- return;
- end if;
-
- -- Set size of component from type. We use the Esize except in a
- -- packed record, where we use the RM_Size (since that is exactly
- -- what the RM_Size value, as distinct from the Object_Size is
- -- useful for!)
-
- if Is_Packed (E) then
- Set_Esize (Comp, RM_Size (Ctyp));
- else
- Set_Esize (Comp, Esize (Ctyp));
- end if;
-
- -- Compute the component position from the previous one. See if
- -- current component requires being on a storage unit boundary.
-
- -- If record is not packed, we always go to a storage unit boundary
-
- if not Is_Packed (E) then
- Forc := True;
-
- -- Packed cases
-
- else
- -- Elementary types do not need SU boundary in packed record
-
- if Is_Elementary_Type (Ctyp) then
- Forc := False;
-
- -- Packed array types with a modular packed array type do not
- -- force a storage unit boundary (since the code generation
- -- treats these as equivalent to the underlying modular type),
-
- elsif Is_Array_Type (Ctyp)
- and then Is_Bit_Packed_Array (Ctyp)
- and then Is_Modular_Integer_Type (Packed_Array_Type (Ctyp))
- then
- Forc := False;
-
- -- Record types with known length less than or equal to the length
- -- of long long integer can also be unaligned, since they can be
- -- treated as scalars.
-
- elsif Is_Record_Type (Ctyp)
- and then not Is_Dynamic_SO_Ref (Esize (Ctyp))
- and then Esize (Ctyp) <= Esize (Standard_Long_Long_Integer)
- then
- Forc := False;
-
- -- All other cases force a storage unit boundary, even when packed
-
- else
- Forc := True;
- end if;
- end if;
-
- -- Now get the next component location
-
- Get_Next_Component_Location
- (Prev_Comp, Alignment (Ctyp), Npos, Fbit, NPMax, Forc);
- Set_Normalized_Position (Comp, Npos);
- Set_Normalized_First_Bit (Comp, Fbit);
- Set_Normalized_Position_Max (Comp, NPMax);
-
- -- Set Component_Bit_Offset in the static case
-
- if Known_Static_Normalized_Position (Comp)
- and then Known_Normalized_First_Bit (Comp)
- then
- Set_Component_Bit_Offset (Comp, SSU * Npos + Fbit);
- end if;
- end Layout_Component;
-
- -----------------------
- -- Layout_Components --
- -----------------------
-
- procedure Layout_Components
- (From : Entity_Id;
- To : Entity_Id;
- Esiz : out SO_Ref;
- RM_Siz : out SO_Ref)
- is
- End_Npos : SO_Ref;
- End_Fbit : SO_Ref;
- End_NPMax : SO_Ref;
-
- begin
- -- Only layout components if there are some to layout!
-
- if Present (From) then
-
- -- Layout components with no component clauses
-
- Comp := From;
- loop
- if (Ekind (Comp) = E_Component
- or else Ekind (Comp) = E_Discriminant)
- and then No (Component_Clause (Comp))
- then
- Layout_Component (Comp, Prev_Comp);
- Prev_Comp := Comp;
- end if;
-
- exit when Comp = To;
- Next_Entity (Comp);
- end loop;
- end if;
-
- -- Set size fields, both are zero if no components
-
- if No (Prev_Comp) then
- Esiz := Uint_0;
- RM_Siz := Uint_0;
-
- else
- -- First the object size, for which we align past the last
- -- field to the alignment of the record (the object size
- -- is required to be a multiple of the alignment).
-
- Get_Next_Component_Location
- (Prev_Comp,
- Alignment (E),
- End_Npos,
- End_Fbit,
- End_NPMax,
- Force_SU => True);
-
- -- If the resulting normalized position is a dynamic reference,
- -- then the size is dynamic, and is stored in storage units.
- -- In this case, we set the RM_Size to the same value, it is
- -- simply not worth distinguishing Esize and RM_Size values in
- -- the dynamic case, since the RM has nothing to say about them.
-
- -- Note that a size cannot have been given in this case, since
- -- size specifications cannot be given for variable length types.
-
- declare
- Align : constant Uint := Alignment (E);
-
- begin
- if Is_Dynamic_SO_Ref (End_Npos) then
- RM_Siz := End_Npos;
-
- -- Set the Object_Size allowing for alignment. In the
- -- dynamic case, we have to actually do the runtime
- -- computation. We can skip this in the non-packed
- -- record case if the last component has a smaller
- -- alignment than the overall record alignment.
-
- if Is_Dynamic_SO_Ref (End_NPMax) then
- Esiz := End_NPMax;
-
- if Is_Packed (E)
- or else Alignment (Prev_Comp) < Align
- then
- -- The expression we build is
- -- (expr + align - 1) / align * align
-
- Esiz :=
- SO_Ref_From_Expr
- (Expr =>
- Make_Op_Multiply (Loc,
- Left_Opnd =>
- Make_Op_Divide (Loc,
- Left_Opnd =>
- Make_Op_Add (Loc,
- Left_Opnd =>
- Expr_From_SO_Ref (Loc, Esiz),
- Right_Opnd =>
- Make_Integer_Literal (Loc,
- Intval => Align - 1)),
- Right_Opnd =>
- Make_Integer_Literal (Loc, Align)),
- Right_Opnd =>
- Make_Integer_Literal (Loc, Align)),
- Ins_Type => E,
- Vtype => E);
- end if;
-
- -- Here Esiz is static, so we can adjust the alignment
- -- directly go give the required aligned value.
-
- else
- Esiz := (End_NPMax + Align - 1) / Align * Align * SSU;
- end if;
-
- -- Case where computed size is static
-
- else
- -- The ending size was computed in Npos in storage units,
- -- but the actual size is stored in bits, so adjust
- -- accordingly. We also adjust the size to match the
- -- alignment here.
-
- Esiz := (End_NPMax + Align - 1) / Align * Align * SSU;
-
- -- Compute the resulting Value_Size (RM_Size). For this
- -- purpose we do not force alignment of the record or
- -- storage size alignment of the result.
-
- Get_Next_Component_Location
- (Prev_Comp,
- Uint_0,
- End_Npos,
- End_Fbit,
- End_NPMax,
- Force_SU => False);
-
- RM_Siz := End_Npos * SSU + End_Fbit;
- Set_And_Check_Static_Size (E, Esiz, RM_Siz);
- end if;
- end;
- end if;
- end Layout_Components;
-
- -------------------------------
- -- Layout_Non_Variant_Record --
- -------------------------------
-
- procedure Layout_Non_Variant_Record is
- Esiz : SO_Ref;
- RM_Siz : SO_Ref;
-
- begin
- Layout_Components (First_Entity (E), Last_Entity (E), Esiz, RM_Siz);
- Set_Esize (E, Esiz);
- Set_RM_Size (E, RM_Siz);
- end Layout_Non_Variant_Record;
-
- ---------------------------
- -- Layout_Variant_Record --
- ---------------------------
-
- procedure Layout_Variant_Record is
- Tdef : constant Node_Id := Type_Definition (Decl);
- Dlist : constant List_Id := Discriminant_Specifications (Decl);
- Esiz : SO_Ref;
- RM_Siz : SO_Ref;
-
- RM_Siz_Expr : Node_Id := Empty;
- -- Expression for the evolving RM_Siz value. This is typically a
- -- conditional expression which involves tests of discriminant
- -- values that are formed as references to the entity V. At
- -- the end of scanning all the components, a suitable function
- -- is constructed in which V is the parameter.
-
- -----------------------
- -- Local Subprograms --
- -----------------------
-
- procedure Layout_Component_List
- (Clist : Node_Id;
- Esiz : out SO_Ref;
- RM_Siz_Expr : out Node_Id);
- -- Recursive procedure, called to layout one component list
- -- Esiz and RM_Siz_Expr are set to the Object_Size and Value_Size
- -- values respectively representing the record size up to and
- -- including the last component in the component list (including
- -- any variants in this component list). RM_Siz_Expr is returned
- -- as an expression which may in the general case involve some
- -- references to the discriminants of the current record value,
- -- referenced by selecting from the entity V.
-
- ---------------------------
- -- Layout_Component_List --
- ---------------------------
-
- procedure Layout_Component_List
- (Clist : Node_Id;
- Esiz : out SO_Ref;
- RM_Siz_Expr : out Node_Id)
- is
- Citems : constant List_Id := Component_Items (Clist);
- Vpart : constant Node_Id := Variant_Part (Clist);
- Prv : Node_Id;
- Var : Node_Id;
- RM_Siz : Uint;
- RMS_Ent : Entity_Id;
-
- begin
- if Is_Non_Empty_List (Citems) then
- Layout_Components
- (From => Defining_Identifier (First (Citems)),
- To => Defining_Identifier (Last (Citems)),
- Esiz => Esiz,
- RM_Siz => RM_Siz);
- else
- Layout_Components (Empty, Empty, Esiz, RM_Siz);
- end if;
-
- -- Case where no variants are present in the component list
-
- if No (Vpart) then
-
- -- The Esiz value has been correctly set by the call to
- -- Layout_Components, so there is nothing more to be done.
-
- -- For RM_Siz, we have an SO_Ref value, which we must convert
- -- to an appropriate expression.
-
- if Is_Static_SO_Ref (RM_Siz) then
- RM_Siz_Expr :=
- Make_Integer_Literal (Loc,
- Intval => RM_Siz);
-
- else
- RMS_Ent := Get_Dynamic_SO_Entity (RM_Siz);
-
- -- If the size is represented by a function, then we
- -- create an appropriate function call using V as
- -- the parameter to the call.
-
- if Is_Discrim_SO_Function (RMS_Ent) then
- RM_Siz_Expr :=
- Make_Function_Call (Loc,
- Name => New_Occurrence_Of (RMS_Ent, Loc),
- Parameter_Associations => New_List (
- Make_Identifier (Loc, Chars => Vname)));
-
- -- If the size is represented by a constant, then the
- -- expression we want is a reference to this constant
-
- else
- RM_Siz_Expr := New_Occurrence_Of (RMS_Ent, Loc);
- end if;
- end if;
-
- -- Case where variants are present in this component list
-
- else
- declare
- EsizV : SO_Ref;
- RM_SizV : Node_Id;
- Dchoice : Node_Id;
- Discrim : Node_Id;
- Dtest : Node_Id;
-
- begin
- RM_Siz_Expr := Empty;
- Prv := Prev_Comp;
-
- Var := Last (Variants (Vpart));
- while Present (Var) loop
- Prev_Comp := Prv;
- Layout_Component_List
- (Component_List (Var), EsizV, RM_SizV);
-
- -- Set the Object_Size. If this is the first variant,
- -- we just set the size of this first variant.
-
- if Var = Last (Variants (Vpart)) then
- Esiz := EsizV;
-
- -- Otherwise the Object_Size is formed as a maximum
- -- of Esiz so far from previous variants, and the new
- -- Esiz value from the variant we just processed.
-
- -- If both values are static, we can just compute the
- -- maximum directly to save building junk nodes.
-
- elsif not Is_Dynamic_SO_Ref (Esiz)
- and then not Is_Dynamic_SO_Ref (EsizV)
- then
- Esiz := UI_Max (Esiz, EsizV);
-
- -- If either value is dynamic, then we have to generate
- -- an appropriate Standard_Unsigned'Max attribute call.
-
- else
- Esiz :=
- SO_Ref_From_Expr
- (Make_Attribute_Reference (Loc,
- Attribute_Name => Name_Max,
- Prefix =>
- New_Occurrence_Of (Standard_Unsigned, Loc),
- Expressions => New_List (
- Expr_From_SO_Ref (Loc, Esiz),
- Expr_From_SO_Ref (Loc, EsizV))),
- Ins_Type => E,
- Vtype => E);
- end if;
-
- -- Now deal with Value_Size (RM_Siz). We are aiming at
- -- an expression that looks like:
-
- -- if xxDx (V.disc) then rmsiz1
- -- else if xxDx (V.disc) then rmsiz2
- -- else ...
-
- -- Where rmsiz1, rmsiz2... are the RM_Siz values for the
- -- individual variants, and xxDx are the discriminant
- -- checking functions generated for the variant type.
-
- -- If this is the first variant, we simply set the
- -- result as the expression. Note that this takes
- -- care of the others case.
-
- if No (RM_Siz_Expr) then
- RM_Siz_Expr := RM_SizV;
-
- -- Otherwise construct the appropriate test
-
- else
- -- Discriminant to be tested
-
- Discrim :=
- Make_Selected_Component (Loc,
- Prefix =>
- Make_Identifier (Loc, Chars => Vname),
- Selector_Name =>
- New_Occurrence_Of
- (Entity (Name (Vpart)), Loc));
-
- -- The test to be used in general is a call to the
- -- discriminant checking function. However, it is
- -- definitely worth special casing the very common
- -- case where a single value is involved.
-
- Dchoice := First (Discrete_Choices (Var));
-
- if No (Next (Dchoice))
- and then Nkind (Dchoice) /= N_Range
- then
- Dtest :=
- Make_Op_Eq (Loc,
- Left_Opnd => Discrim,
- Right_Opnd => New_Copy (Dchoice));
-
- else
- Dtest :=
- Make_Function_Call (Loc,
- Name =>
- New_Occurrence_Of
- (Dcheck_Function (Var), Loc),
- Parameter_Associations => New_List (Discrim));
- end if;
-
- RM_Siz_Expr :=
- Make_Conditional_Expression (Loc,
- Expressions =>
- New_List (Dtest, RM_SizV, RM_Siz_Expr));
- end if;
-
- Prev (Var);
- end loop;
- end;
- end if;
- end Layout_Component_List;
-
- -- Start of processing for Layout_Variant_Record
-
- begin
- -- We need the discriminant checking functions, since we generate
- -- calls to these functions for the RM_Size expression, so make
- -- sure that these functions have been constructed in time.
-
- Build_Discr_Checking_Funcs (Decl);
-
- -- Layout the discriminants
-
- Layout_Components
- (From => Defining_Identifier (First (Dlist)),
- To => Defining_Identifier (Last (Dlist)),
- Esiz => Esiz,
- RM_Siz => RM_Siz);
-
- -- Layout the main component list (this will make recursive calls
- -- to layout all component lists nested within variants).
-
- Layout_Component_List (Component_List (Tdef), Esiz, RM_Siz_Expr);
- Set_Esize (E, Esiz);
-
- -- If the RM_Size is a literal, set its value
-
- if Nkind (RM_Siz_Expr) = N_Integer_Literal then
- Set_RM_Size (E, Intval (RM_Siz_Expr));
-
- -- Otherwise we construct a dynamic SO_Ref
-
- else
- Set_RM_Size (E,
- SO_Ref_From_Expr
- (RM_Siz_Expr,
- Ins_Type => E,
- Vtype => E));
- end if;
- end Layout_Variant_Record;
-
- -- Start of processing for Layout_Record_Type
-
- begin
- -- If this is a cloned subtype, just copy the size fields from the
- -- original, nothing else needs to be done in this case, since the
- -- components themselves are all shared.
-
- if (Ekind (E) = E_Record_Subtype
- or else Ekind (E) = E_Class_Wide_Subtype)
- and then Present (Cloned_Subtype (E))
- then
- Set_Esize (E, Esize (Cloned_Subtype (E)));
- Set_RM_Size (E, RM_Size (Cloned_Subtype (E)));
- Set_Alignment (E, Alignment (Cloned_Subtype (E)));
-
- -- Another special case, class-wide types. The RM says that the size
- -- of such types is implementation defined (RM 13.3(48)). What we do
- -- here is to leave the fields set as unknown values, and the backend
- -- determines the actual behavior.
-
- elsif Ekind (E) = E_Class_Wide_Type then
- null;
-
- -- All other cases
-
- else
- -- Initialize aligment conservatively to 1. This value will
- -- be increased as necessary during processing of the record.
-
- if Unknown_Alignment (E) then
- Set_Alignment (E, Uint_1);
- end if;
-
- -- Initialize previous component. This is Empty unless there
- -- are components which have already been laid out by component
- -- clauses. If there are such components, we start our layout of
- -- the remaining components following the last such component
-
- Prev_Comp := Empty;
-
- Comp := First_Entity (E);
- while Present (Comp) loop
- if (Ekind (Comp) = E_Component
- or else Ekind (Comp) = E_Discriminant)
- and then Present (Component_Clause (Comp))
- then
- if No (Prev_Comp)
- or else
- Component_Bit_Offset (Comp) >
- Component_Bit_Offset (Prev_Comp)
- then
- Prev_Comp := Comp;
- end if;
- end if;
-
- Next_Entity (Comp);
- end loop;
-
- -- We have two separate circuits, one for non-variant records and
- -- one for variant records. For non-variant records, we simply go
- -- through the list of components. This handles all the non-variant
- -- cases including those cases of subtypes where there is no full
- -- type declaration, so the tree cannot be used to drive the layout.
- -- For variant records, we have to drive the layout from the tree
- -- since we need to understand the variant structure in this case.
-
- if Present (Full_View (E)) then
- Decl := Declaration_Node (Full_View (E));
- else
- Decl := Declaration_Node (E);
- end if;
-
- -- Scan all the components
-
- if Nkind (Decl) = N_Full_Type_Declaration
- and then Has_Discriminants (E)
- and then Nkind (Type_Definition (Decl)) = N_Record_Definition
- and then
- Present (Variant_Part (Component_List (Type_Definition (Decl))))
- then
- Layout_Variant_Record;
- else
- Layout_Non_Variant_Record;
- end if;
- end if;
- end Layout_Record_Type;
-
- -----------------
- -- Layout_Type --
- -----------------
-
- procedure Layout_Type (E : Entity_Id) is
- begin
- -- For string literal types, for now, kill the size always, this
- -- is because gigi does not like or need the size to be set ???
-
- if Ekind (E) = E_String_Literal_Subtype then
- Set_Esize (E, Uint_0);
- Set_RM_Size (E, Uint_0);
- return;
- end if;
-
- -- For access types, set size/alignment. This is system address
- -- size, except for fat pointers (unconstrained array access types),
- -- where the size is two times the address size, to accommodate the
- -- two pointers that are required for a fat pointer (data and
- -- template). Note that E_Access_Protected_Subprogram_Type is not
- -- an access type for this purpose since it is not a pointer but is
- -- equivalent to a record. For access subtypes, copy the size from
- -- the base type since Gigi represents them the same way.
-
- if Is_Access_Type (E) then
-
- -- If Esize already set (e.g. by a size clause), then nothing
- -- further to be done here.
-
- if Known_Esize (E) then
- null;
-
- -- Access to subprogram is a strange beast, and we let the
- -- backend figure out what is needed (it may be some kind
- -- of fat pointer, including the static link for example.
-
- elsif Ekind (E) = E_Access_Protected_Subprogram_Type then
- null;
-
- -- For access subtypes, copy the size information from base type
-
- elsif Ekind (E) = E_Access_Subtype then
- Set_Size_Info (E, Base_Type (E));
- Set_RM_Size (E, RM_Size (Base_Type (E)));
-
- -- For other access types, we use either address size, or, if
- -- a fat pointer is used (pointer-to-unconstrained array case),
- -- twice the address size to accommodate a fat pointer.
-
- else
- declare
- Desig : Entity_Id := Designated_Type (E);
-
- begin
- if Is_Private_Type (Desig)
- and then Present (Full_View (Desig))
- then
- Desig := Full_View (Desig);
- end if;
-
- if (Is_Array_Type (Desig)
- and then not Is_Constrained (Desig)
- and then not Has_Completion_In_Body (Desig)
- and then not Debug_Flag_6)
- then
- Init_Size (E, 2 * System_Address_Size);
-
- -- Check for bad convention set
-
- if Convention (E) = Convention_C
- or else
- Convention (E) = Convention_CPP
- then
- Error_Msg_N
- ("?this access type does not " &
- "correspond to C pointer", E);
- end if;
-
- else
- Init_Size (E, System_Address_Size);
- end if;
- end;
- end if;
-
- Set_Prim_Alignment (E);
-
- -- Scalar types: set size and alignment
-
- elsif Is_Scalar_Type (E) then
-
- -- For discrete types, the RM_Size and Esize must be set
- -- already, since this is part of the earlier processing
- -- and the front end is always required to layout the
- -- sizes of such types (since they are available as static
- -- attributes). All we do is to check that this rule is
- -- indeed obeyed!
-
- if Is_Discrete_Type (E) then
-
- -- If the RM_Size is not set, then here is where we set it.
-
- -- Note: an RM_Size of zero looks like not set here, but this
- -- is a rare case, and we can simply reset it without any harm.
-
- if not Known_RM_Size (E) then
- Set_Discrete_RM_Size (E);
- end if;
-
- -- If Esize for a discrete type is not set then set it
-
- if not Known_Esize (E) then
- declare
- S : Int := 8;
-
- begin
- loop
- -- If size is big enough, set it and exit
-
- if S >= RM_Size (E) then
- Init_Esize (E, S);
- exit;
-
- -- If the RM_Size is greater than 64 (happens only
- -- when strange values are specified by the user,
- -- then Esize is simply a copy of RM_Size, it will
- -- be further refined later on)
-
- elsif S = 64 then
- Set_Esize (E, RM_Size (E));
- exit;
-
- -- Otherwise double possible size and keep trying
-
- else
- S := S * 2;
- end if;
- end loop;
- end;
- end if;
-
- -- For non-discrete sclar types, if the RM_Size is not set,
- -- then set it now to a copy of the Esize if the Esize is set.
-
- else
- if Known_Esize (E) and then Unknown_RM_Size (E) then
- Set_RM_Size (E, Esize (E));
- end if;
- end if;
-
- Set_Prim_Alignment (E);
-
- -- Non-primitive types
-
- else
- -- If RM_Size is known, set Esize if not known
-
- if Known_RM_Size (E) and then Unknown_Esize (E) then
-
- -- If the alignment is known, we bump the Esize up to the
- -- next alignment boundary if it is not already on one.
-
- if Known_Alignment (E) then
- declare
- A : constant Uint := Alignment_In_Bits (E);
- S : constant SO_Ref := RM_Size (E);
-
- begin
- Set_Esize (E, (S * A + A - 1) / A);
- end;
- end if;
-
- -- If Esize is set, and RM_Size is not, RM_Size is copied from
- -- Esize at least for now this seems reasonable, and is in any
- -- case needed for compatibility with old versions of gigi.
- -- look to be unknown.
-
- elsif Known_Esize (E) and then Unknown_RM_Size (E) then
- Set_RM_Size (E, Esize (E));
- end if;
-
- -- For array base types, set component size if object size of
- -- the component type is known and is a small power of 2 (8,
- -- 16, 32, 64), since this is what will always be used.
-
- if Ekind (E) = E_Array_Type
- and then Unknown_Component_Size (E)
- then
- declare
- CT : constant Entity_Id := Component_Type (E);
-
- begin
- -- For some reasons, access types can cause trouble,
- -- So let's just do this for discrete types ???
-
- if Present (CT)
- and then Is_Discrete_Type (CT)
- and then Known_Static_Esize (CT)
- then
- declare
- S : constant Uint := Esize (CT);
-
- begin
- if S = 8 or else
- S = 16 or else
- S = 32 or else
- S = 64
- then
- Set_Component_Size (E, Esize (CT));
- end if;
- end;
- end if;
- end;
- end if;
- end if;
-
- -- Layout array and record types if front end layout set
-
- if Frontend_Layout_On_Target then
- if Is_Array_Type (E) and then not Is_Bit_Packed_Array (E) then
- Layout_Array_Type (E);
- elsif Is_Record_Type (E) then
- Layout_Record_Type (E);
- end if;
- end if;
- end Layout_Type;
-
- ---------------------
- -- Rewrite_Integer --
- ---------------------
-
- procedure Rewrite_Integer (N : Node_Id; V : Uint) is
- Loc : constant Source_Ptr := Sloc (N);
- Typ : constant Entity_Id := Etype (N);
-
- begin
- Rewrite (N, Make_Integer_Literal (Loc, Intval => V));
- Set_Etype (N, Typ);
- end Rewrite_Integer;
-
- -------------------------------
- -- Set_And_Check_Static_Size --
- -------------------------------
-
- procedure Set_And_Check_Static_Size
- (E : Entity_Id;
- Esiz : SO_Ref;
- RM_Siz : SO_Ref)
- is
- SC : Node_Id;
-
- procedure Check_Size_Too_Small (Spec : Uint; Min : Uint);
- -- Spec is the number of bit specified in the size clause, and
- -- Min is the minimum computed size. An error is given that the
- -- specified size is too small if Spec < Min, and in this case
- -- both Esize and RM_Size are set to unknown in E. The error
- -- message is posted on node SC.
-
- procedure Check_Unused_Bits (Spec : Uint; Max : Uint);
- -- Spec is the number of bits specified in the size clause, and
- -- Max is the maximum computed size. A warning is given about
- -- unused bits if Spec > Max. This warning is posted on node SC.
-
- --------------------------
- -- Check_Size_Too_Small --
- --------------------------
-
- procedure Check_Size_Too_Small (Spec : Uint; Min : Uint) is
- begin
- if Spec < Min then
- Error_Msg_Uint_1 := Min;
- Error_Msg_NE
- ("size for & too small, minimum allowed is ^", SC, E);
- Init_Esize (E);
- Init_RM_Size (E);
- end if;
- end Check_Size_Too_Small;
-
- -----------------------
- -- Check_Unused_Bits --
- -----------------------
-
- procedure Check_Unused_Bits (Spec : Uint; Max : Uint) is
- begin
- if Spec > Max then
- Error_Msg_Uint_1 := Spec - Max;
- Error_Msg_NE ("?^ bits of & unused", SC, E);
- end if;
- end Check_Unused_Bits;
-
- -- Start of processing for Set_And_Check_Static_Size
-
- begin
- -- Case where Object_Size (Esize) is already set by a size clause
-
- if Known_Static_Esize (E) then
- SC := Size_Clause (E);
-
- if No (SC) then
- SC := Get_Attribute_Definition_Clause (E, Attribute_Object_Size);
- end if;
-
- -- Perform checks on specified size against computed sizes
-
- if Present (SC) then
- Check_Unused_Bits (Esize (E), Esiz);
- Check_Size_Too_Small (Esize (E), RM_Siz);
- end if;
- end if;
-
- -- Case where Value_Size (RM_Size) is set by specific Value_Size
- -- clause (we do not need to worry about Value_Size being set by
- -- a Size clause, since that will have set Esize as well, and we
- -- already took care of that case).
-
- if Known_Static_RM_Size (E) then
- SC := Get_Attribute_Definition_Clause (E, Attribute_Value_Size);
-
- -- Perform checks on specified size against computed sizes
-
- if Present (SC) then
- Check_Unused_Bits (RM_Size (E), Esiz);
- Check_Size_Too_Small (RM_Size (E), RM_Siz);
- end if;
- end if;
-
- -- Set sizes if unknown
-
- if Unknown_Esize (E) then
- Set_Esize (E, Esiz);
- end if;
-
- if Unknown_RM_Size (E) then
- Set_RM_Size (E, RM_Siz);
- end if;
- end Set_And_Check_Static_Size;
-
- --------------------------
- -- Set_Discrete_RM_Size --
- --------------------------
-
- procedure Set_Discrete_RM_Size (Def_Id : Entity_Id) is
- FST : constant Entity_Id := First_Subtype (Def_Id);
-
- begin
- -- All discrete types except for the base types in standard
- -- are constrained, so indicate this by setting Is_Constrained.
-
- Set_Is_Constrained (Def_Id);
-
- -- We set generic types to have an unknown size, since the
- -- representation of a generic type is irrelevant, in view
- -- of the fact that they have nothing to do with code.
-
- if Is_Generic_Type (Root_Type (FST)) then
- Set_RM_Size (Def_Id, Uint_0);
-
- -- If the subtype statically matches the first subtype, then
- -- it is required to have exactly the same layout. This is
- -- required by aliasing considerations.
-
- elsif Def_Id /= FST and then
- Subtypes_Statically_Match (Def_Id, FST)
- then
- Set_RM_Size (Def_Id, RM_Size (FST));
- Set_Size_Info (Def_Id, FST);
-
- -- In all other cases the RM_Size is set to the minimum size.
- -- Note that this routine is never called for subtypes for which
- -- the RM_Size is set explicitly by an attribute clause.
-
- else
- Set_RM_Size (Def_Id, UI_From_Int (Minimum_Size (Def_Id)));
- end if;
- end Set_Discrete_RM_Size;
-
- ------------------------
- -- Set_Prim_Alignment --
- ------------------------
-
- procedure Set_Prim_Alignment (E : Entity_Id) is
- begin
- -- Do not set alignment for packed array types, unless we are doing
- -- front end layout, because otherwise this is always handled in the
- -- backend.
-
- if Is_Packed_Array_Type (E) and then not Frontend_Layout_On_Target then
- return;
-
- -- If there is an alignment clause, then we respect it
-
- elsif Has_Alignment_Clause (E) then
- return;
-
- -- If the size is not set, then don't attempt to set the alignment. This
- -- happens in the backend layout case for access to subprogram types.
-
- elsif not Known_Static_Esize (E) then
- return;
-
- -- For access types, do not set the alignment if the size is less than
- -- the allowed minimum size. This avoids cascaded error messages.
-
- elsif Is_Access_Type (E)
- and then Esize (E) < System_Address_Size
- then
- return;
- end if;
-
- -- Here we calculate the alignment as the largest power of two
- -- multiple of System.Storage_Unit that does not exceed either
- -- the actual size of the type, or the maximum allowed alignment.
-
- declare
- S : constant Int :=
- UI_To_Int (Esize (E)) / SSU;
- A : Nat;
-
- begin
- A := 1;
- while 2 * A <= Ttypes.Maximum_Alignment
- and then 2 * A <= S
- loop
- A := 2 * A;
- end loop;
-
- -- Now we think we should set the alignment to A, but we
- -- skip this if an alignment is already set to a value
- -- greater than A (happens for derived types).
-
- -- However, if the alignment is known and too small it
- -- must be increased, this happens in a case like:
-
- -- type R is new Character;
- -- for R'Size use 16;
-
- -- Here the alignment inherited from Character is 1, but
- -- it must be increased to 2 to reflect the increased size.
-
- if Unknown_Alignment (E) or else Alignment (E) < A then
- Init_Alignment (E, A);
- end if;
- end;
- end Set_Prim_Alignment;
-
- ----------------------
- -- SO_Ref_From_Expr --
- ----------------------
-
- function SO_Ref_From_Expr
- (Expr : Node_Id;
- Ins_Type : Entity_Id;
- Vtype : Entity_Id := Empty)
- return Dynamic_SO_Ref
- is
- Loc : constant Source_Ptr := Sloc (Ins_Type);
-
- K : constant Entity_Id :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('K'));
-
- Decl : Node_Id;
-
- function Check_Node_V_Ref (N : Node_Id) return Traverse_Result;
- -- Function used to check one node for reference to V
-
- function Has_V_Ref is new Traverse_Func (Check_Node_V_Ref);
- -- Function used to traverse tree to check for reference to V
-
- ----------------------
- -- Check_Node_V_Ref --
- ----------------------
-
- function Check_Node_V_Ref (N : Node_Id) return Traverse_Result is
- begin
- if Nkind (N) = N_Identifier then
- if Chars (N) = Vname then
- return Abandon;
- else
- return Skip;
- end if;
-
- else
- return OK;
- end if;
- end Check_Node_V_Ref;
-
- -- Start of processing for SO_Ref_From_Expr
-
- begin
- -- Case of expression is an integer literal, in this case we just
- -- return the value (which must always be non-negative, since size
- -- and offset values can never be negative).
-
- if Nkind (Expr) = N_Integer_Literal then
- pragma Assert (Intval (Expr) >= 0);
- return Intval (Expr);
- end if;
-
- -- Case where there is a reference to V, create function
-
- if Has_V_Ref (Expr) = Abandon then
-
- pragma Assert (Present (Vtype));
- Set_Is_Discrim_SO_Function (K);
-
- Decl :=
- Make_Subprogram_Body (Loc,
-
- Specification =>
- Make_Function_Specification (Loc,
- Defining_Unit_Name => K,
- Parameter_Specifications => New_List (
- Make_Parameter_Specification (Loc,
- Defining_Identifier =>
- Make_Defining_Identifier (Loc, Chars => Vname),
- Parameter_Type =>
- New_Occurrence_Of (Vtype, Loc))),
- Subtype_Mark =>
- New_Occurrence_Of (Standard_Unsigned, Loc)),
-
- Declarations => Empty_List,
-
- Handled_Statement_Sequence =>
- Make_Handled_Sequence_Of_Statements (Loc,
- Statements => New_List (
- Make_Return_Statement (Loc,
- Expression => Expr))));
-
- -- No reference to V, create constant
-
- else
- Decl :=
- Make_Object_Declaration (Loc,
- Defining_Identifier => K,
- Object_Definition =>
- New_Occurrence_Of (Standard_Unsigned, Loc),
- Constant_Present => True,
- Expression => Expr);
- end if;
-
- Append_Freeze_Action (Ins_Type, Decl);
- Analyze (Decl);
- return Create_Dynamic_SO_Ref (K);
- end SO_Ref_From_Expr;
-
-end Layout;
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