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diff --git a/src/evaluation.ads b/src/evaluation.ads new file mode 100644 index 000000000..66ec2a1cc --- /dev/null +++ b/src/evaluation.ads @@ -0,0 +1,161 @@ +-- 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 Iirs; use Iirs; + +package 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. + function Get_Physical_Value (Expr : Iir) return Iir_Int64; + + -- 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; + + -- 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 range expression A_RANGE is not included in SUB_TYPE. + 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 : Iir_Int64; Bound : Iir) return Boolean; + + -- Return the length of the discrete range CONSTRAINT. + function Eval_Discrete_Range_Length (Constraint : Iir) return Iir_Int64; + + -- Return the length of SUB_TYPE. + function Eval_Discrete_Type_Length (Sub_Type : Iir) return Iir_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 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 Iir_Int64; + + -- 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 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 : Iir_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 : Iir_Int64; Loc : Location_Type) + return Iir; + + -- Store into NAME_BUFFER, NAME_LENGTH the simple name, character literal + -- or operator sumbol of ID, using the same format as SIMPLE_NAME + -- attribute. + procedure Eval_Simple_Name (Id : Name_Id); + + -- 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; + + -- 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; +end Evaluation; |