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Minor reformatting.

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(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 --
-- --
-- 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);