------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- R E P I N F O -- -- -- -- S p e c -- -- -- -- Copyright (C) 1999-2004 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. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- This package contains the routines to handle back annotation of the -- tree to fill in representation information, and also the routine used -- by -gnatR to print this information. This unit is used both in the -- compiler and in ASIS (it is used in ASIS as part of the implementation -- of the data decomposition annex. with Types; use Types; with Uintp; use Uintp; package Repinfo is -------------------------------- -- Representation Information -- -------------------------------- -- The representation information of interest here is size and -- component information for arrays and records. For primitive -- types, the front end computes the Esize and RM_Size fields of -- the corresponding entities as constant non-negative integers, -- and the Uint values are stored directly in these fields. -- For composite types, there are three cases: -- 1. In some cases the front end knows the values statically, -- for example in the ase where representation clauses or -- pragmas specify the values. -- 2. If Backend_Layout is True, then the backend is responsible -- for layout of all types and objects not laid out by the -- front end. This includes all dynamic values, and also -- static values (e.g. record sizes) when not set by the -- front end. -- 3. If Backend_Layout is False, then the front end lays out -- all data, according to target dependent size and alignment -- information, creating dynamic inlinable functions where -- needed in the case of sizes not known till runtime. ----------------------------- -- Back-Annotation by Gigi -- ----------------------------- -- The following interface is used by gigi if Backend_Layout is True -- As part of the processing in gigi, the types are laid out and -- appropriate values computed for the sizes and component positions -- and sizes of records and arrays. -- The back-annotation circuit in gigi is responsible for updating the -- relevant fields in the tree to reflect these computations, as follows: -- For E_Array_Type entities, the Component_Size field -- For all record and array types and subtypes, the Esize field, -- which contains the Size (more accurately the Object_SIze) value -- for the type or subtype. -- For E_Component and E_Distriminant entities, the Esize (size -- of component) and Component_Bit_Offset fields. Note that gigi -- does not (yet ???) back annotate Normalized_Position/First_Bit. -- There are three cases to consider: -- 1. The value is constant. In this case, the back annotation works -- by simply storing the non-negative universal integer value in -- the appropriate field corresponding to this constant size. -- 2. The value depends on variables other than discriminants of the -- current record. In this case, the value is not known, even if -- the complete data of the record is available, and gigi marks -- this situation by storing the special value No_Uint. -- 3. The value depends on the discriminant values for the current -- record. In this case, gigi back annotates the field with a -- representation of the expression for computing the value in -- terms of the discriminants. A negative Uint value is used to -- represent the value of such an expression, as explained in -- the following section. -- GCC expressions are represented with a Uint value that is negative. -- See the body of this package for details on the representation used. -- One other case in which gigi back annotates GCC expressions is in -- the Present_Expr field of an N_Variant node. This expression which -- will always depend on discriminants, and hence always be represented -- as a negative Uint value, provides an expression which, when evaluated -- with a given set of discriminant values, indicates whether the variant -- is present for that set of values (result is True, i.e. non-zero) or -- not present (result is False, i.e. zero). subtype Node_Ref is Uint; -- Subtype used for negative Uint values used to represent nodes subtype Node_Ref_Or_Val is Uint; -- Subtype used for values that can either be a Node_Ref (negative) -- or a value (non-negative) type TCode is range 0 .. 27; -- Type used on Ada side to represent DEFTREECODE values defined in -- tree.def. Only a subset of these tree codes can actually appear. -- The names are the names from tree.def in Ada casing. -- name code description operands Cond_Expr : constant TCode := 1; -- conditional 3 Plus_Expr : constant TCode := 2; -- addition 2 Minus_Expr : constant TCode := 3; -- subtraction 2 Mult_Expr : constant TCode := 4; -- multiplication 2 Trunc_Div_Expr : constant TCode := 5; -- truncating division 2 Ceil_Div_Expr : constant TCode := 6; -- division rounding up 2 Floor_Div_Expr : constant TCode := 7; -- division rounding down 2 Trunc_Mod_Expr : constant TCode := 8; -- mod for trunc_div 2 Ceil_Mod_Expr : constant TCode := 9; -- mod for ceil_div 2 Floor_Mod_Expr : constant TCode := 10; -- mod for floor_div 2 Exact_Div_Expr : constant TCode := 11; -- exact div 2 Negate_Expr : constant TCode := 12; -- negation 1 Min_Expr : constant TCode := 13; -- minimum 2 Max_Expr : constant TCode := 14; -- maximum 2 Abs_Expr : constant TCode := 15; -- absolute value 1 Truth_Andif_Expr : constant TCode := 16; -- Boolean and then 2 Truth_Orif_Expr : constant TCode := 17; -- Boolean or else 2 Truth_And_Expr : constant TCode := 18; -- Boolean and 2 Truth_Or_Expr : constant TCode := 19; -- Boolean or 2 Truth_Xor_Expr : constant TCode := 20; -- Boolean xor 2 Truth_Not_Expr : constant TCode := 21; -- Boolean not 1 Lt_Expr : constant TCode := 22; -- comparision < 2 Le_Expr : constant TCode := 23; -- comparision <= 2 Gt_Expr : constant TCode := 24; -- comparision > 2 Ge_Expr : constant TCode := 25; -- comparision >= 2 Eq_Expr : constant TCode := 26; -- comparision = 2 Ne_Expr : constant TCode := 27; -- comparision /= 2 -- The following entry is used to represent a discriminant value in -- the tree. It has a special tree code that does not correspond -- directly to a gcc node. The single operand is the number of the -- discriminant in the record (1 = first discriminant). Discrim_Val : constant TCode := 0; -- discriminant value 1 ------------------------ -- The gigi Interface -- ------------------------ -- The following declarations are for use by gigi for back annotation function Create_Node (Expr : TCode; Op1 : Node_Ref_Or_Val; Op2 : Node_Ref_Or_Val := No_Uint; Op3 : Node_Ref_Or_Val := No_Uint) return Node_Ref; -- Creates a node with using the tree code defined by Expr and from -- 1-3 operands as required (unused operands set as shown to No_Uint) -- Note that this call can be used to create a discriminant reference -- by using (Expr => Discrim_Val, Op1 => discriminant_number). function Create_Discrim_Ref (Discr : Entity_Id) return Node_Ref; -- Creates a refrerence to the discriminant whose entity is Discr -------------------------------------------------------- -- Front-End Interface for Dynamic Size/Offset Values -- -------------------------------------------------------- -- If Backend_Layout is False, then the front-end deals with all -- dynamic size and offset fields. There are two cases: -- 1. The value can be computed at the time of type freezing, and -- is stored in a run-time constant. In this case, the field -- contains a reference to this entity. In the case of sizes -- the value stored is the size in storage units, since dynamic -- sizes are always a multiple of storage units. -- 2. The size/offset depends on the value of discriminants at -- run-time. In this case, the front end builds a function to -- compute the value. This function has a single parameter -- which is the discriminated record object in question. Any -- references to discriminant values are simply references to -- the appropriate discriminant in this single argument, and -- to compute the required size/offset value at run time, the -- code generator simply constructs a call to the function -- with the appropriate argument. The size/offset field in -- this case contains a reference to the function entity. -- Note that as for case 1, if such a function is used to -- return a size, then the size in storage units is returned, -- not the size in bits. -- The interface here allows these created entities to be referenced -- using negative Unit values, so that they can be stored in the -- appropriate size and offset fields in the tree. -- In the case of components, if the location of the component is static, -- then all four fields (Component_Bit_Offset, Normalized_Position, Esize, -- and Normalized_First_Bit) are set to appropraite values. In the case of -- a non-static component location, Component_Bit_Offset is not used and -- is left set to Unknown. Normalized_Position and Normalized_First_Bit -- are set appropriately. subtype SO_Ref is Uint; -- Type used to represent a Uint value that represents a static or -- dynamic size/offset value (non-negative if static, negative if -- the size value is dynamic). subtype Dynamic_SO_Ref is Uint; -- Type used to represent a negative Uint value used to store -- a dynamic size/offset value. function Is_Dynamic_SO_Ref (U : SO_Ref) return Boolean; pragma Inline (Is_Dynamic_SO_Ref); -- Given a SO_Ref (Uint) value, returns True iff the SO_Ref value -- represents a dynamic Size/Offset value (i.e. it is negative). function Is_Static_SO_Ref (U : SO_Ref) return Boolean; pragma Inline (Is_Static_SO_Ref); -- Given a SO_Ref (Uint) value, returns True iff the SO_Ref value -- represents a static Size/Offset value (i.e. it is non-negative). function Create_Dynamic_SO_Ref (E : Entity_Id) return Dynamic_SO_Ref; -- Given the Entity_Id for a constant (case 1), the Node_Id for an -- expression (case 2), or the Entity_Id for a function (case 3), -- this function returns a (negative) Uint value that can be used -- to retrieve the entity or expression for later use. function Get_Dynamic_SO_Entity (U : Dynamic_SO_Ref) return Entity_Id; -- Retrieve the Node_Id or Entity_Id stored by a previous call to -- Create_Dynamic_SO_Ref. The approach is that the front end makes -- the necessary Create_Dynamic_SO_Ref calls to associate the node -- and entity id values and the back end makes Get_Dynamic_SO_Ref -- calls to retrive them. -------------------- -- ASIS_Interface -- -------------------- type Discrim_List is array (Pos range <>) of Uint; -- Type used to represent list of discriminant values function Rep_Value (Val : Node_Ref_Or_Val; D : Discrim_List) return Uint; -- Given the contents of a First_Bit_Position or Esize field containing -- a node reference (i.e. a negative Uint value) and D, the list of -- discriminant values, returns the interpreted value of this field. -- For convenience, Rep_Value will take a non-negative Uint value -- as an argument value, and return it unmodified. A No_Uint value is -- also returned unmodified. procedure Tree_Read; -- Initializes internal tables from current tree file using the relevant -- Table.Tree_Read routines. ------------------------ -- Compiler Interface -- ------------------------ procedure List_Rep_Info; -- Procedure to list representation information procedure Tree_Write; -- Writes out internal tables to current tree file using the relevant -- Table.Tree_Write routines. -------------------------- -- Debugging Procedures -- -------------------------- procedure List_GCC_Expression (U : Node_Ref_Or_Val); -- Prints out given expression in symbolic form. Constants are listed -- in decimal numeric form, Discriminants are listed with a # followed -- by the discriminant number, and operators are output in appropriate -- symbolic form No_Uint displays as two question marks. The output is -- on a single line but has no line return after it. This procedure is -- useful only if operating in backend layout mode. procedure lgx (U : Node_Ref_Or_Val); -- In backend layout mode, this is like List_GCC_Expression, but -- includes a line return at the end. If operating in front end -- layout mode, then the name of the entity for the size (either -- a function of a variable) is listed followed by a line return. end Repinfo;