-- Evaluation of static expressions. -- Copyright (C) 2002, 2003, 2004, 2005 Tristan Gingold -- -- GHDL is free software; you can redistribute it and/or modify it under -- the terms of the GNU General Public License as published by the Free -- Software Foundation; either version 2, or (at your option) any later -- version. -- -- GHDL is distributed in the hope that it will be useful, but WITHOUT 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 -- along with GHDL; see the file COPYING. If not, write to the Free -- Software Foundation, 59 Temple Place - Suite 330, Boston, MA -- 02111-1307, USA. with Types; use Types; with Vhdl.Nodes; use Vhdl.Nodes; package Vhdl.Evaluation is -- Evaluation is about compile-time computation of expressions, such as -- 2 + 1 --> 3. This is (of course) possible only with locally (and some -- globally) static expressions. Evaluation is required during semantic -- analysis at many places (in fact those where locally static expression -- are required by the language). For example, the type of O'Range (N) -- depends on N, so we need to evaluate N. -- -- The result of evaluation is a literal (integer, enumeration, real, -- physical), a string or a simple aggregate. For scalar types, the -- result is therefore normalized (there is only one kind of result), but -- for array types, the result isn't: in general it will be a string, but -- it may be a simple aggregate. Strings are preferred (because they are -- more compact), but aren't possible in some cases. For example, the -- evaluation of "Text" & NUL cannot be a string. -- -- Some functions (like Eval_Static_Expr) simply returns a result (which -- may be a node of the expression), others returns a result and set the -- origin (Literal_Origin or Range_Origin) to remember the original -- expression that was evaluation. The original expression is kept so that -- it is possible to print the original tree. -- Get the value of a physical integer literal or unit. May propagate -- Constraint_Error. function Get_Physical_Value (Expr : Iir) return Int64; -- Get the parameter of an attribute, or 1 if doesn't exist. function Eval_Attribute_Parameter_Or_1 (Attr : Iir) return Natural; -- Evaluate the locally static expression EXPR (without checking that EXPR -- is locally static). Return a literal or an aggregate, without setting -- the origin, and do not modify EXPR. This can be used only to get the -- value of an expression, without replacing it. function Eval_Static_Expr (Expr: Iir) return Iir; -- Evaluate (ie compute) expression EXPR. -- EXPR is required to be a locally static expression, otherwise an error -- message is generated. -- The result is a literal with the origin set. function Eval_Expr (Expr: Iir) return Iir; -- Same as Eval_Expr, but if EXPR is not locally static, the result is -- EXPR. Also, if EXPR is null_iir, then null_iir is returned. -- The purpose of this function is to evaluate an expression only if it -- is locally static. function Eval_Expr_If_Static (Expr : Iir) return Iir; -- Concatenate all the elements of OPERANDS. -- The first element of OPERANDS is the rightest one, the last the -- leftest one. All the elements are concatenation operators. -- All the elements are static. function Eval_Concatenation (Operands : Iir_Array) return Iir; -- Evaluate a physical literal and return a normalized literal (using -- the primary unit as unit). function Eval_Physical_Literal (Expr : Iir) return Iir; -- Return TRUE if literal EXPR is in SUB_TYPE bounds. function Eval_Is_In_Bound (Expr : Iir; Sub_Type : Iir) return Boolean; -- Emit an error if EXPR violates SUB_TYPE bounds. procedure Eval_Check_Bound (Expr : Iir; Sub_Type : Iir); -- Same as Eval_Expr, but a range check with SUB_TYPE is performed after -- computation. function Eval_Expr_Check (Expr : Iir; Sub_Type : Iir) return Iir; -- Call Eval_Expr_Check only if EXPR is static. function Eval_Expr_Check_If_Static (Expr : Iir; Atype : Iir) return Iir; -- For a locally static range RNG (a range expression, a range attribute -- or a name that denotes a type or a subtype) returns its corresponding -- locally static range_expression. The bounds of the results are also -- literals. -- Return a range_expression or NULL_IIR for a non locally static range. function Eval_Static_Range (Rng : Iir) return Iir; -- Return a locally static range expression with the origin set for ARANGE. function Eval_Range (Arange : Iir) return Iir; -- If ARANGE is a locally static range, return locally static range -- expression (with the origin set), else return ARANGE. function Eval_Range_If_Static (Arange : Iir) return Iir; -- Emit an error if A_RANGE is not included in SUB_TYPE. A_RANGE can be -- a range expression, a range attribute or a name that denotes a discrete -- type or subtype. A_RANGE must be a locally static range. procedure Eval_Check_Range (A_Range : Iir; Sub_Type : Iir; Any_Dir : Boolean); -- Return TRUE if A_RANGE is compatible with SUB_TYPE. Compatibility is -- defined in LRM: -- -- LRM08 5.2 Scalar types -- A range constraint is /compatible/ with a subtype if each bound of the -- range belongs to the subtype or if the range constraint defines a null -- range. function Eval_Is_Range_In_Bound (A_Range : Iir; Sub_Type : Iir; Any_Dir : Boolean) return Boolean; -- Return TRUE iff VAL belongs to BOUND. function Eval_Int_In_Range (Val : Int64; Bound : Iir) return Boolean; -- Return the length of the discrete range CONSTRAINT. function Eval_Discrete_Range_Length (Constraint : Iir) return Int64; -- Return the length of SUB_TYPE. function Eval_Discrete_Type_Length (Sub_Type : Iir) return Int64; -- Get the left bound of a range constraint. -- Note: the range constraint may be an attribute or a subtype. function Eval_Discrete_Range_Left (Constraint : Iir) return Iir; -- Return true iff RNG is a null range. function Eval_Is_Null_Discrete_Range (Rng : Iir) return Boolean; -- Return the position of EXPR, ie the result of sub_type'pos (EXPR), where -- sub_type is the type of expr. -- EXPR must be of a discrete subtype. function Eval_Pos (Expr : Iir) return Int64; -- Return True iff L and R (scalar literals) are equal. function Eval_Is_Eq (L, R : Iir) return Boolean; -- Replace ORIGIN (an overflow literal) with extreme positive value (if -- IS_POS is true) or extreme negative value. function Build_Extreme_Value (Is_Pos : Boolean; Origin : Iir) return Iir; -- Create a Iir_Kind_Overflow node of type EXPR_TYPE for ORIGIN. function Build_Overflow (Origin : Iir; Expr_Type : Iir) return Iir; -- Fill VECT with choices from CHOICES_CHAIN: each position of CHOICE_RANGE -- is associated with its corresponding choice from CHOICES_CHAIN. -- VECT bounds must be 0 .. Len - 1, where Len is the length of -- CHOICE_RANGE. procedure Build_Array_Choices_Vector (Vect : out Iir_Array; Choice_Range : Iir; Choices_Chain : Iir); -- Create an array subtype from LEN and BASE_TYPE, according to rules -- of LRM93 7.3.2.2. (which are the same as LRM93 7.2.4). function Create_Unidim_Array_By_Length (Base_Type : Iir; Len : Int64; Loc : Iir) return Iir_Array_Subtype_Definition; -- Create a subtype of A_TYPE whose length is LEN. -- This is used to create subtypes for strings or aggregates. function Create_Range_Subtype_By_Length (A_Type : Iir; Len : Int64; Loc : Location_Type) return Iir; -- Compute ATYPE'value (VALUE) using origin ORIG, but without checking -- bounds. function Eval_Value_Attribute (Value : String; Atype : Iir; Orig : Iir) return Iir; -- From one-dimensional array expression PREFIX extract element at -- offset OFF (from 0 to length - 1). Note that the element is directly -- returned, not a copy of it (so it should be referenced if stored in -- the tree). function Eval_Indexed_Name_By_Offset (Prefix : Iir; Off : Iir_Index32) return Iir; -- Return the simple name, character literal or operator sumbol of ID, -- using the same format as SIMPLE_NAME attribute. function Eval_Simple_Name (Id : Name_Id) return String; -- Compare two string literals (of same length). type Compare_Type is (Compare_Lt, Compare_Eq, Compare_Gt); function Compare_String_Literals (L, R : Iir) return Compare_Type; package String_Utils is type Str_Info (Is_String : Boolean := True) is record Len : Nat32; case Is_String is when True => Id : String8_Id; when False => -- A simple aggregate. List of elements. List : Iir_Flist; end case; end record; -- Fill Res from EL. This is used to speed up Lt and Eq operations. function Get_Str_Info (Expr : Iir) return Str_Info; -- Return the position of element IDX of STR. function Get_Pos (Str : Str_Info; Idx : Nat32) return Iir_Int32; end String_Utils; -- Return the local part of 'Instance_Name or 'Path_Name. type Path_Instance_Name_Type (Len : Natural) is record -- The node before suffix (entity, architecture or generate iterator). Path_Instance : Iir; -- The suffix Suffix : String (1 .. Len); end record; function Get_Path_Instance_Name_Suffix (Attr : Iir) return Path_Instance_Name_Type; -- Create a copy of VAL. function Copy_Constant (Val : Iir) return Iir; end Vhdl.Evaluation;