diff --git a/gcc/ada/checks.ads b/gcc/ada/checks.ads index 5810bcbe4f9..c16495dd1a2 100644 --- a/gcc/ada/checks.ads +++ b/gcc/ada/checks.ads @@ -6,7 +6,7 @@ -- -- -- S p e c -- -- -- --- Copyright (C) 1992-2004 Free Software Foundation, Inc. -- +-- Copyright (C) 1992-2005 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- -- @@ -159,16 +159,20 @@ package Checks is OK : out Boolean; Lo : out Uint; Hi : out Uint); - -- N is a node for a subexpression. If N is of a discrete type with - -- no error indications, and no other peculiarities (e.g. missing - -- type fields), then OK is True on return, and Lo and Hi are set - -- to a conservative estimate of the possible range of values of N. - -- Thus if OK is True on return, the value of the subexpression N is - -- known to like in the range Lo .. Hi (inclusive). If the expression - -- is not of a discrete type, or some kind of error condition is - -- detected, then OK is False on exit, and Lo/Hi are set to No_Uint. - -- Thus the significance of OK being False on return is that no - -- useful information is available on the range of the expression. + -- N is a node for a subexpression. If N is of a discrete type with no + -- error indications, and no other peculiarities (e.g. missing type + -- fields), then OK is True on return, and Lo and Hi are set to a + -- conservative estimate of the possible range of values of N. Thus if OK + -- is True on return, the value of the subexpression N is known to like in + -- the range Lo .. Hi (inclusive). If the expression is not of a discrete + -- type, or some kind of error condition is detected, then OK is False on + -- exit, and Lo/Hi are set to No_Uint. Thus the significance of OK being + -- False on return is that no useful information is available on the range + -- of the expression. + + procedure Install_Null_Excluding_Check (N : Node_Id); + -- Determines whether an access node requires a runtime access check and + -- if so inserts the appropriate run-time check. ------------------------------------------------------- -- Control and Optimization of Range/Overflow Checks -- @@ -181,12 +185,12 @@ package Checks is -- in the transitional phase where some of these checks are still done -- by the back end, but many are done by the front end. - -- Overflow checks are similarly controlled by the Do_Overflow_Check - -- flag. The difference here is that if Backend_Overflow_Checks is - -- is (Backend_Overflow_Checks_On_Target set False), then the actual - -- overflow checks are generated by the front end, but if back end - -- overflow checks are active (Backend_Overflow_Checks_On_Target - -- set True), then the back end does generate the checks. + -- Overflow checks are similarly controlled by the Do_Overflow_Check flag. + -- The difference here is that if Backend_Overflow_Checks is is + -- (Backend_Overflow_Checks_On_Target set False), then the actual overflow + -- checks are generated by the front end, but if back end overflow checks + -- are active (Backend_Overflow_Checks_On_Target set True), then the back + -- end does generate the checks. -- The following two routines are used to set these flags, they allow -- for the possibility of eliminating checks. Checks can be eliminated @@ -266,17 +270,16 @@ package Checks is -- The checks operate in one of two modes: - -- If Source_Typ is Empty, then the node Expr is examined, at the - -- very least to get the source subtype. In addition for some of - -- the checks, the actual form of the node may be examined. For - -- example, a node of type Integer whose actual form is an Integer - -- conversion from a type with range 0 .. 3 can be determined to - -- have a value in the range 0 .. 3. + -- If Source_Typ is Empty, then the node Expr is examined, at the very + -- least to get the source subtype. In addition for some of the checks, + -- the actual form of the node may be examined. For example, a node of + -- type Integer whose actual form is an Integer conversion from a type + -- with range 0 .. 3 can be determined to have a value in range 0 .. 3. - -- If Source_Typ is given, then nothing can be assumed about the - -- Expr, and indeed its contents are not examined. In this case the - -- check is based on the assumption that Expr can be an arbitrary - -- value of the given Source_Typ. + -- If Source_Typ is given, then nothing can be assumed about the Expr, + -- and indeed its contents are not examined. In this case the check is + -- based on the assumption that Expr can be an arbitrary value of the + -- given Source_Typ. -- Currently, the only case in which a Source_Typ is explicitly supplied -- is for the case of Out and In_Out parameters, where, for the conversion @@ -293,8 +296,8 @@ package Checks is -- to Insert_Actions. -- -- For access types, the Directly_Designated_Type is retrieved and - -- processing continues as enumerated above, with a guard against - -- null values. + -- processing continues as enumerated above, with a guard against null + -- values. -- -- Note: calls to Apply_Length_Check currently never supply an explicit -- Source_Typ parameter, but Apply_Length_Check takes this parameter and @@ -305,9 +308,9 @@ package Checks is (Ck_Node : Node_Id; Target_Typ : Entity_Id; Source_Typ : Entity_Id := Empty); - -- For an Node of kind N_Range, constructs a range check action that - -- tests first that the range is not null and then that the range - -- is contained in the Target_Typ range. + -- For an Node of kind N_Range, constructs a range check action that tests + -- first that the range is not null and then that the range is contained in + -- the Target_Typ range. -- -- For scalar types, constructs a range check action that first tests that -- the expression is contained in the Target_Typ range. The difference @@ -318,13 +321,13 @@ package Checks is -- to check that each Expr range is properly contained in the range of -- Target_Typ. -- - -- For a type conversion to an unconstrained array type, constructs - -- a range check action to check that the bounds of the source type - -- are within the constraints imposed by the Target_Typ. + -- For a type conversion to an unconstrained array type, constructs a range + -- check action to check that the bounds of the source type are within the + -- constraints imposed by the Target_Typ. -- -- For access types, the Directly_Designated_Type is retrieved and - -- processing continues as enumerated above, with a guard against - -- null values. + -- processing continues as enumerated above, with a guard against null + -- values. -- -- The source type is used by type conversions to unconstrained array -- types to retrieve the corresponding bounds. @@ -344,10 +347,10 @@ package Checks is Source_Typ : Entity_Id := Empty; Fixed_Int : Boolean := False); -- For scalar types, determines whether an expression node should be - -- flagged as needing a runtime range check. If the node requires such - -- a check, the Do_Range_Check flag is turned on. The Fixed_Int flag - -- if set causes any fixed-point values to be treated as though they - -- were discrete values (i.e. the underlying integer value is used). + -- flagged as needing a runtime range check. If the node requires such a + -- check, the Do_Range_Check flag is turned on. The Fixed_Int flag if set + -- causes any fixed-point values to be treated as though they were discrete + -- values (i.e. the underlying integer value is used). type Check_Result is private; -- Type used to return result of Range_Check call, for later use in @@ -360,12 +363,11 @@ package Checks is Static_Sloc : Source_Ptr; Flag_Node : Node_Id); -- Called to append range checks as returned by a call to Range_Check. - -- Stmts is a list to which either the dynamic check is appended or - -- the raise Constraint_Error statement is appended (for static checks). - -- Static_Sloc is the Sloc at which the raise CE node points, - -- Flag_Node is used as the node at which to set the Has_Dynamic_Check - -- flag. Checks_On is a boolean value that says if range and index checking - -- is on or not. + -- Stmts is a list to which either the dynamic check is appended or the + -- raise Constraint_Error statement is appended (for static checks). + -- Static_Sloc is the Sloc at which the raise CE node points, Flag_Node is + -- used as the node at which to set the Has_Dynamic_Check flag. Checks_On + -- is a boolean value that says if range and index checking is on or not. procedure Insert_Range_Checks (Checks : Check_Result; @@ -402,12 +404,12 @@ package Checks is -- Expander Routines -- ----------------------- - -- Some of the earlier processing for checks results in temporarily - -- setting the Do_Range_Check flag rather than actually generating - -- checks. Now we are moving the generation of such checks into the - -- front end for reasons of efficiency and simplicity (there were - -- difficutlies in handling this in the back end when side effects - -- were present in the expressions being checked). + -- Some of the earlier processing for checks results in temporarily setting + -- the Do_Range_Check flag rather than actually generating checks. Now we + -- are moving the generation of such checks into the front end for reasons + -- of efficiency and simplicity (there were difficutlies in handling this + -- in the back end when side effects were present in the expressions being + -- checked). -- Probably we could eliminate the Do_Range_Check flag entirely and -- generate the checks earlier, but this is a delicate area and it @@ -419,37 +421,36 @@ package Checks is (N : Node_Id; Target_Type : Entity_Id; Reason : RT_Exception_Code); - -- This procedure is called to actually generate and insert a range - -- check. A check is generated to ensure that the value of N lies - -- within the range of the target type. Note that the base type of - -- N may be different from the base type of the target type. This - -- happens in the conversion case. The Reason parameter is the - -- exception code to be used for the exception if raised. + -- This procedure is called to actually generate and insert a range check. + -- A check is generated to ensure that the value of N lies within the range + -- of the target type. Note that the base type of N may be different from + -- the base type of the target type. This happens in the conversion case. + -- The Reason parameter is the exception code to be used for the exception + -- if raised. -- - -- Note on the relation of this routine to the Do_Range_Check flag. - -- Mostly for historical reasons, we often set the Do_Range_Check - -- flag and then later we call Generate_Range_Check if this flag is - -- set. Most probably we could eliminate this intermediate setting - -- of the flag (historically the back end dealt with range checks, - -- using this flag to indicate if a check was required, then we - -- moved checks into the front end). + -- Note on the relation of this routine to the Do_Range_Check flag. Mostly + -- for historical reasons, we often set the Do_Range_Check flag and then + -- later we call Generate_Range_Check if this flag is set. Most probably we + -- could eliminate this intermediate setting of the flag (historically the + -- back end dealt with range checks, using this flag to indicate if a check + -- was required, then we moved checks into the front end). procedure Generate_Index_Checks (N : Node_Id); - -- This procedure is called to generate index checks on the subscripts - -- for the indexed component node N. Each subscript expression is - -- examined, and if the Do_Range_Check flag is set, an appropriate - -- index check is generated and the flag is reset. + -- This procedure is called to generate index checks on the subscripts for + -- the indexed component node N. Each subscript expression is examined, and + -- if the Do_Range_Check flag is set, an appropriate index check is + -- generated and the flag is reset. -- Similarly, we set the flag Do_Discriminant_Check in the semantic - -- analysis to indicate that a discriminant check is required for a - -- selected component of a discriminated type. The following routine - -- is called from the expander to actually generate the call. + -- analysis to indicate that a discriminant check is required for selected + -- component of a discriminated type. The following routine is called from + -- the expander to actually generate the call. procedure Generate_Discriminant_Check (N : Node_Id); - -- N is a selected component for which a discriminant check is required - -- to make sure that the discriminants have appropriate values for the - -- selection. This is done by calling the appropriate discriminant - -- checking routine for the selector. + -- N is a selected component for which a discriminant check is required to + -- make sure that the discriminants have appropriate values for the + -- selection. This is done by calling the appropriate discriminant checking + -- routine for the selector. ----------------------- -- Validity Checking -- @@ -457,15 +458,15 @@ package Checks is -- In (RM 13.9.1(9-11)) we have the following rules on invalid values - -- If the representation of a scalar object does not represent a - -- value of the object's subtype (perhaps because the object was not - -- initialized), the object is said to have an invalid representation. - -- It is a bounded error to evaluate the value of such an object. If - -- the error is detected, either Constraint_Error or Program_Error is - -- raised. Otherwise, execution continues using the invalid - -- representation. The rules of the language outside this subclause - -- assume that all objects have valid representations. The semantics - -- of operations on invalid representations are as follows: + -- If the representation of a scalar object does not represent value of + -- the object's subtype (perhaps because the object was not initialized), + -- the object is said to have an invalid representation. It is a bounded + -- error to evaluate the value of such an object. If the error is + -- detected, either Constraint_Error or Program_Error is raised. + -- Otherwise, execution continues using the invalid representation. The + -- rules of the language outside this subclause assume that all objects + -- have valid representations. The semantics of operations on invalid + -- representations are as follows: -- -- 10 If the representation of the object represents a value of the -- object's type, the value of the type is used. @@ -483,9 +484,9 @@ package Checks is -- array assignments, where we don't want to do wild stores, and case -- statements where we don't want to do wild jumps. - -- In GNAT, we control validity checking with a switch -gnatV that - -- can take three parameters, n/d/f for None/Default/Full. These - -- modes have the following meanings: + -- In GNAT, we control validity checking with a switch -gnatV that can take + -- three parameters, n/d/f for None/Default/Full. These modes have the + -- following meanings: -- None (no validity checking) @@ -577,12 +578,12 @@ package Checks is -- are checked for validity. procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id); - -- Expr is a lvalue, i.e. an expression representing the target of - -- an assignment. This procedure checks for this expression involving - -- an assignment to an array value. We have to be sure that all the - -- subscripts in such a case are valid, since according to the rules - -- in (RM 13.9.1(9-11)) such assignments are not permitted to result - -- in erroneous behavior in the case of invalid subscript values. + -- Expr is a lvalue, i.e. an expression representing the target of an + -- assignment. This procedure checks for this expression involving an + -- assignment to an array value. We have to be sure that all the subscripts + -- in such a case are valid, since according to the rules in (RM + -- 13.9.1(9-11)) such assignments are not permitted to result in erroneous + -- behavior in the case of invalid subscript values. procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False); -- Ensure that Expr represents a valid value of its type. If this type @@ -602,14 +603,14 @@ package Checks is -- valid, raising Constraint_Error if the value is not valid. function Expr_Known_Valid (Expr : Node_Id) return Boolean; - -- This function tests it the value of Expr is known to be valid in - -- the sense of RM 13.9.1(9-11). In the case of GNAT, it is only - -- discrete types which are a concern, since for non-discrete types - -- we simply continue computation with invalid values, which does - -- not lead to erroneous behavior. Thus Expr_Known_Valid always - -- returns True if the type of Expr is non-discrete. For discrete - -- types the value returned is True only if it can be determined - -- that the value is Valid. Otherwise False is returned. + -- This function tests it the value of Expr is known to be valid in the + -- sense of RM 13.9.1(9-11). In the case of GNAT, it is only discrete types + -- which are a concern, since for non-discrete types we simply continue + -- computation with invalid values, which does not lead to erroneous + -- behavior. Thus Expr_Known_Valid always returns True if the type of Expr + -- is non-discrete. For discrete types the value returned is True only if + -- it can be determined that the value is Valid. Otherwise False is + -- returned. procedure Insert_Valid_Check (Expr : Node_Id); -- Inserts code that will check for the value of Expr being valid, in @@ -635,12 +636,12 @@ private -- responsibility of the caller to rewrite and substitute the nodes with -- N_Raise_Constraint_Error nodes. -- - -- For the non-static case a single N_Raise_Constraint_Error node - -- with a non-empty Condition field is returned. + -- For the non-static case a single N_Raise_Constraint_Error node with a + -- non-empty Condition field is returned. -- - -- Unused entries in Check_Result, if any, are simply set to Empty - -- For external clients, the required processing on this result is - -- achieved using the Insert_Range_Checks routine. + -- Unused entries in Check_Result, if any, are simply set to Empty For + -- external clients, the required processing on this result is achieved + -- using the Insert_Range_Checks routine. pragma Inline (Apply_Length_Check); pragma Inline (Apply_Range_Check);