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Minor reformatting. 

(Install_Null_Excluding_Check): Moved to the package specification
to use it from other packages to generate the run-time check
associated with the null-exclusion attribute.

From-SVN: r103896
This commit is contained in:
Arnaud Charlet 2005-09-05 10:12:03 +02:00
parent d124a2302d
commit 1525324e88
1 changed files with 109 additions and 108 deletions
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gcc/ada/checks.ads
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@ -6,7 +6,7 @@
-- -- -- --
-- S p e c -- -- 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 -- -- 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- -- -- terms of the GNU General Public License as published by the Free Soft- --
@ -159,16 +159,20 @@ package Checks is
OK : out Boolean; OK : out Boolean;
Lo : out Uint; Lo : out Uint;
Hi : out Uint); Hi : out Uint);
-- N is a node for a subexpression. If N is of a discrete type with -- N is a node for a subexpression. If N is of a discrete type with no
-- no error indications, and no other peculiarities (e.g. missing -- error indications, and no other peculiarities (e.g. missing type
-- type fields), then OK is True on return, and Lo and Hi are set -- fields), then OK is True on return, and Lo and Hi are set to a
-- to a conservative estimate of the possible range of values of N. -- conservative estimate of the possible range of values of N. Thus if OK
-- Thus if OK is True on return, the value of the subexpression N is -- is True on return, the value of the subexpression N is known to like in
-- known to like in the range Lo .. Hi (inclusive). If the expression -- the range Lo .. Hi (inclusive). If the expression is not of a discrete
-- is not of a discrete type, or some kind of error condition is -- type, or some kind of error condition is detected, then OK is False on
-- detected, then OK is False on exit, and Lo/Hi are set to No_Uint. -- exit, and Lo/Hi are set to No_Uint. Thus the significance of OK being
-- Thus the significance of OK being False on return is that no -- False on return is that no useful information is available on the range
-- useful information is available on the range of the expression. -- 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 -- -- 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 -- in the transitional phase where some of these checks are still done
-- by the back end, but many are done by the front end. -- by the back end, but many are done by the front end.
-- Overflow checks are similarly controlled by the Do_Overflow_Check -- Overflow checks are similarly controlled by the Do_Overflow_Check flag.
-- flag. The difference here is that if Backend_Overflow_Checks is -- The difference here is that if Backend_Overflow_Checks is is
-- is (Backend_Overflow_Checks_On_Target set False), then the actual -- (Backend_Overflow_Checks_On_Target set False), then the actual overflow
-- overflow checks are generated by the front end, but if back end -- checks are generated by the front end, but if back end overflow checks
-- overflow checks are active (Backend_Overflow_Checks_On_Target -- are active (Backend_Overflow_Checks_On_Target set True), then the back
-- set True), then the back end does generate the checks. -- end does generate the checks.
-- The following two routines are used to set these flags, they allow -- The following two routines are used to set these flags, they allow
-- for the possibility of eliminating checks. Checks can be eliminated -- 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: -- The checks operate in one of two modes:
-- If Source_Typ is Empty, then the node Expr is examined, at the -- If Source_Typ is Empty, then the node Expr is examined, at the very
-- very least to get the source subtype. In addition for some of -- least to get the source subtype. In addition for some of the checks,
-- the checks, the actual form of the node may be examined. For -- the actual form of the node may be examined. For example, a node of
-- example, a node of type Integer whose actual form is an Integer -- type Integer whose actual form is an Integer conversion from a type
-- conversion from a type with range 0 .. 3 can be determined to -- with range 0 .. 3 can be determined to have a value in range 0 .. 3.
-- have a value in the range 0 .. 3.
-- If Source_Typ is given, then nothing can be assumed about the -- If Source_Typ is given, then nothing can be assumed about the Expr,
-- Expr, and indeed its contents are not examined. In this case the -- and indeed its contents are not examined. In this case the check is
-- check is based on the assumption that Expr can be an arbitrary -- based on the assumption that Expr can be an arbitrary value of the
-- value of the given Source_Typ. -- given Source_Typ.
-- Currently, the only case in which a Source_Typ is explicitly supplied -- 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 -- is for the case of Out and In_Out parameters, where, for the conversion
@ -293,8 +296,8 @@ package Checks is
-- to Insert_Actions. -- to Insert_Actions.
-- --
-- For access types, the Directly_Designated_Type is retrieved and -- For access types, the Directly_Designated_Type is retrieved and
-- processing continues as enumerated above, with a guard against -- processing continues as enumerated above, with a guard against null
-- null values. -- values.
-- --
-- Note: calls to Apply_Length_Check currently never supply an explicit -- Note: calls to Apply_Length_Check currently never supply an explicit
-- Source_Typ parameter, but Apply_Length_Check takes this parameter and -- Source_Typ parameter, but Apply_Length_Check takes this parameter and
@ -305,9 +308,9 @@ package Checks is
(Ck_Node : Node_Id; (Ck_Node : Node_Id;
Target_Typ : Entity_Id; Target_Typ : Entity_Id;
Source_Typ : Entity_Id := Empty); Source_Typ : Entity_Id := Empty);
-- For an Node of kind N_Range, constructs a range check action that -- For an Node of kind N_Range, constructs a range check action that tests
-- tests first that the range is not null and then that the range -- first that the range is not null and then that the range is contained in
-- is contained in the Target_Typ range. -- the Target_Typ range.
-- --
-- For scalar types, constructs a range check action that first tests that -- For scalar types, constructs a range check action that first tests that
-- the expression is contained in the Target_Typ range. The difference -- 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 -- to check that each Expr range is properly contained in the range of
-- Target_Typ. -- Target_Typ.
-- --
-- For a type conversion to an unconstrained array type, constructs -- For a type conversion to an unconstrained array type, constructs a range
-- a range check action to check that the bounds of the source type -- check action to check that the bounds of the source type are within the
-- are within the constraints imposed by the Target_Typ. -- constraints imposed by the Target_Typ.
-- --
-- For access types, the Directly_Designated_Type is retrieved and -- For access types, the Directly_Designated_Type is retrieved and
-- processing continues as enumerated above, with a guard against -- processing continues as enumerated above, with a guard against null
-- null values. -- values.
-- --
-- The source type is used by type conversions to unconstrained array -- The source type is used by type conversions to unconstrained array
-- types to retrieve the corresponding bounds. -- types to retrieve the corresponding bounds.
@ -344,10 +347,10 @@ package Checks is
Source_Typ : Entity_Id := Empty; Source_Typ : Entity_Id := Empty;
Fixed_Int : Boolean := False); Fixed_Int : Boolean := False);
-- For scalar types, determines whether an expression node should be -- For scalar types, determines whether an expression node should be
-- flagged as needing a runtime range check. If the node requires such -- flagged as needing a runtime range check. If the node requires such a
-- a check, the Do_Range_Check flag is turned on. The Fixed_Int flag -- check, the Do_Range_Check flag is turned on. The Fixed_Int flag if set
-- if set causes any fixed-point values to be treated as though they -- causes any fixed-point values to be treated as though they were discrete
-- were discrete values (i.e. the underlying integer value is used). -- values (i.e. the underlying integer value is used).
type Check_Result is private; type Check_Result is private;
-- Type used to return result of Range_Check call, for later use in -- Type used to return result of Range_Check call, for later use in
@ -360,12 +363,11 @@ package Checks is
Static_Sloc : Source_Ptr; Static_Sloc : Source_Ptr;
Flag_Node : Node_Id); Flag_Node : Node_Id);
-- Called to append range checks as returned by a call to Range_Check. -- 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 -- Stmts is a list to which either the dynamic check is appended or the
-- the raise Constraint_Error statement is appended (for static checks). -- raise Constraint_Error statement is appended (for static checks).
-- Static_Sloc is the Sloc at which the raise CE node points, -- Static_Sloc is the Sloc at which the raise CE node points, Flag_Node is
-- Flag_Node is used as the node at which to set the Has_Dynamic_Check -- used as the node at which to set the Has_Dynamic_Check flag. Checks_On
-- flag. Checks_On is a boolean value that says if range and index checking -- is a boolean value that says if range and index checking is on or not.
-- is on or not.
procedure Insert_Range_Checks procedure Insert_Range_Checks
(Checks : Check_Result; (Checks : Check_Result;
@ -402,12 +404,12 @@ package Checks is
-- Expander Routines -- -- Expander Routines --
----------------------- -----------------------
-- Some of the earlier processing for checks results in temporarily -- Some of the earlier processing for checks results in temporarily setting
-- setting the Do_Range_Check flag rather than actually generating -- the Do_Range_Check flag rather than actually generating checks. Now we
-- checks. Now we are moving the generation of such checks into the -- are moving the generation of such checks into the front end for reasons
-- front end for reasons of efficiency and simplicity (there were -- of efficiency and simplicity (there were difficutlies in handling this
-- difficutlies in handling this in the back end when side effects -- in the back end when side effects were present in the expressions being
-- were present in the expressions being checked). -- checked).
-- Probably we could eliminate the Do_Range_Check flag entirely and -- Probably we could eliminate the Do_Range_Check flag entirely and
-- generate the checks earlier, but this is a delicate area and it -- generate the checks earlier, but this is a delicate area and it
@ -419,37 +421,36 @@ package Checks is
(N : Node_Id; (N : Node_Id;
Target_Type : Entity_Id; Target_Type : Entity_Id;
Reason : RT_Exception_Code); Reason : RT_Exception_Code);
-- This procedure is called to actually generate and insert a range -- This procedure is called to actually generate and insert a range check.
-- check. A check is generated to ensure that the value of N lies -- A check is generated to ensure that the value of N lies within the range
-- within the range of the target type. Note that the base type of -- of the target type. Note that the base type of N may be different from
-- N may be different from the base type of the target type. This -- the base type of the target type. This happens in the conversion case.
-- happens in the conversion case. The Reason parameter is the -- The Reason parameter is the exception code to be used for the exception
-- exception code to be used for the exception if raised. -- if raised.
-- --
-- Note on the relation of this routine to the Do_Range_Check flag. -- Note on the relation of this routine to the Do_Range_Check flag. Mostly
-- Mostly for historical reasons, we often set the Do_Range_Check -- for historical reasons, we often set the Do_Range_Check flag and then
-- flag and then later we call Generate_Range_Check if this flag is -- later we call Generate_Range_Check if this flag is set. Most probably we
-- set. Most probably we could eliminate this intermediate setting -- could eliminate this intermediate setting of the flag (historically the
-- of the flag (historically the back end dealt with range checks, -- back end dealt with range checks, using this flag to indicate if a check
-- using this flag to indicate if a check was required, then we -- was required, then we moved checks into the front end).
-- moved checks into the front end).
procedure Generate_Index_Checks (N : Node_Id); procedure Generate_Index_Checks (N : Node_Id);
-- This procedure is called to generate index checks on the subscripts -- This procedure is called to generate index checks on the subscripts for
-- for the indexed component node N. Each subscript expression is -- the indexed component node N. Each subscript expression is examined, and
-- examined, and if the Do_Range_Check flag is set, an appropriate -- if the Do_Range_Check flag is set, an appropriate index check is
-- index check is generated and the flag is reset. -- generated and the flag is reset.
-- Similarly, we set the flag Do_Discriminant_Check in the semantic -- Similarly, we set the flag Do_Discriminant_Check in the semantic
-- analysis to indicate that a discriminant check is required for a -- analysis to indicate that a discriminant check is required for selected
-- selected component of a discriminated type. The following routine -- component of a discriminated type. The following routine is called from
-- is called from the expander to actually generate the call. -- the expander to actually generate the call.
procedure Generate_Discriminant_Check (N : Node_Id); procedure Generate_Discriminant_Check (N : Node_Id);
-- N is a selected component for which a discriminant check is required -- N is a selected component for which a discriminant check is required to
-- to make sure that the discriminants have appropriate values for the -- make sure that the discriminants have appropriate values for the
-- selection. This is done by calling the appropriate discriminant -- selection. This is done by calling the appropriate discriminant checking
-- checking routine for the selector. -- routine for the selector.
----------------------- -----------------------
-- Validity Checking -- -- Validity Checking --
@ -457,15 +458,15 @@ package Checks is
-- In (RM 13.9.1(9-11)) we have the following rules on invalid values -- 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 -- If the representation of a scalar object does not represent value of
-- value of the object's subtype (perhaps because the object was not -- the object's subtype (perhaps because the object was not initialized),
-- initialized), the object is said to have an invalid representation. -- the object is said to have an invalid representation. It is a bounded
-- It is a bounded error to evaluate the value of such an object. If -- error to evaluate the value of such an object. If the error is
-- the error is detected, either Constraint_Error or Program_Error is -- detected, either Constraint_Error or Program_Error is raised.
-- raised. Otherwise, execution continues using the invalid -- Otherwise, execution continues using the invalid representation. The
-- representation. The rules of the language outside this subclause -- rules of the language outside this subclause assume that all objects
-- assume that all objects have valid representations. The semantics -- have valid representations. The semantics of operations on invalid
-- of operations on invalid representations are as follows: -- representations are as follows:
-- --
-- 10 If the representation of the object represents a value of the -- 10 If the representation of the object represents a value of the
-- object's type, the value of the type is used. -- 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 -- array assignments, where we don't want to do wild stores, and case
-- statements where we don't want to do wild jumps. -- statements where we don't want to do wild jumps.
-- In GNAT, we control validity checking with a switch -gnatV that -- In GNAT, we control validity checking with a switch -gnatV that can take
-- can take three parameters, n/d/f for None/Default/Full. These -- three parameters, n/d/f for None/Default/Full. These modes have the
-- modes have the following meanings: -- following meanings:
-- None (no validity checking) -- None (no validity checking)
@ -577,12 +578,12 @@ package Checks is
-- are checked for validity. -- are checked for validity.
procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id); procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id);
-- Expr is a lvalue, i.e. an expression representing the target of -- Expr is a lvalue, i.e. an expression representing the target of an
-- an assignment. This procedure checks for this expression involving -- assignment. This procedure checks for this expression involving an
-- an assignment to an array value. We have to be sure that all the -- assignment to an array value. We have to be sure that all the subscripts
-- subscripts in such a case are valid, since according to the rules -- in such a case are valid, since according to the rules in (RM
-- in (RM 13.9.1(9-11)) such assignments are not permitted to result -- 13.9.1(9-11)) such assignments are not permitted to result in erroneous
-- in erroneous behavior in the case of invalid subscript values. -- behavior in the case of invalid subscript values.
procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False); procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False);
-- Ensure that Expr represents a valid value of its type. If this type -- 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. -- valid, raising Constraint_Error if the value is not valid.
function Expr_Known_Valid (Expr : Node_Id) return Boolean; function Expr_Known_Valid (Expr : Node_Id) return Boolean;
-- This function tests it the value of Expr is known to be valid in -- This function tests it the value of Expr is known to be valid in the
-- the sense of RM 13.9.1(9-11). In the case of GNAT, it is only -- sense of RM 13.9.1(9-11). In the case of GNAT, it is only discrete types
-- discrete types which are a concern, since for non-discrete types -- which are a concern, since for non-discrete types we simply continue
-- we simply continue computation with invalid values, which does -- computation with invalid values, which does not lead to erroneous
-- not lead to erroneous behavior. Thus Expr_Known_Valid always -- behavior. Thus Expr_Known_Valid always returns True if the type of Expr
-- returns True if the type of Expr is non-discrete. For discrete -- is non-discrete. For discrete types the value returned is True only if
-- types the value returned is True only if it can be determined -- it can be determined that the value is Valid. Otherwise False is
-- that the value is Valid. Otherwise False is returned. -- returned.
procedure Insert_Valid_Check (Expr : Node_Id); procedure Insert_Valid_Check (Expr : Node_Id);
-- Inserts code that will check for the value of Expr being valid, in -- 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 -- responsibility of the caller to rewrite and substitute the nodes with
-- N_Raise_Constraint_Error nodes. -- N_Raise_Constraint_Error nodes.
-- --
-- For the non-static case a single N_Raise_Constraint_Error node -- For the non-static case a single N_Raise_Constraint_Error node with a
-- with a non-empty Condition field is returned. -- non-empty Condition field is returned.
-- --
-- Unused entries in Check_Result, if any, are simply set to Empty -- Unused entries in Check_Result, if any, are simply set to Empty For
-- For external clients, the required processing on this result is -- external clients, the required processing on this result is achieved
-- achieved using the Insert_Range_Checks routine. -- using the Insert_Range_Checks routine.
pragma Inline (Apply_Length_Check); pragma Inline (Apply_Length_Check);
pragma Inline (Apply_Range_Check); pragma Inline (Apply_Range_Check);