X-Git-Url: https://oss.titaniummirror.com/gitweb?a=blobdiff_plain;f=gcc%2Fada%2Fchecks.ads;fp=gcc%2Fada%2Fchecks.ads;h=0000000000000000000000000000000000000000;hb=6fed43773c9b0ce596dca5686f37ac3fc0fa11c0;hp=69eccc1e57f8362121b6ec75384b9fc63d4e7efa;hpb=27b11d56b743098deb193d510b337ba22dc52e5c;p=msp430-gcc.git diff --git a/gcc/ada/checks.ads b/gcc/ada/checks.ads deleted file mode 100644 index 69eccc1e..00000000 --- a/gcc/ada/checks.ads +++ /dev/null @@ -1,533 +0,0 @@ ------------------------------------------------------------------------------- --- -- --- GNAT COMPILER COMPONENTS -- --- -- --- C H E C K S -- --- -- --- S p e c -- --- -- --- $Revision: 1.2.10.1 $ --- -- --- Copyright (C) 1992-2001 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- -- --- ware Foundation; either version 2, or (at your option) any later ver- -- --- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- --- OUT 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 distributed with GNAT; see file COPYING. If not, write -- --- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- --- MA 02111-1307, USA. -- --- -- --- GNAT was originally developed by the GNAT team at New York University. -- --- Extensive contributions were provided by Ada Core Technologies Inc. -- --- -- ------------------------------------------------------------------------------- - --- Package containing routines used to deal with runtime checks. These --- routines are used both by the semantics and by the expander. In some --- cases, checks are enabled simply by setting flags for gigi, and in --- other cases the code for the check is expanded. - --- The approach used for range and length checks, in regards to suppressed --- checks, is to attempt to detect at compilation time that a constraint --- error will occur. If this is detected a warning or error is issued and the --- offending expression or statement replaced with a constraint error node. --- This always occurs whether checks are suppressed or not. Dynamic range --- checks are, of course, not inserted if checks are suppressed. - -with Types; use Types; -with Uintp; use Uintp; - -package Checks is - - procedure Initialize; - -- Called for each new main source program, to initialize internal - -- variables used in the package body of the Checks unit. - - function Access_Checks_Suppressed (E : Entity_Id) return Boolean; - function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean; - function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean; - function Division_Checks_Suppressed (E : Entity_Id) return Boolean; - function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean; - function Index_Checks_Suppressed (E : Entity_Id) return Boolean; - function Length_Checks_Suppressed (E : Entity_Id) return Boolean; - function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean; - function Range_Checks_Suppressed (E : Entity_Id) return Boolean; - function Storage_Checks_Suppressed (E : Entity_Id) return Boolean; - function Tag_Checks_Suppressed (E : Entity_Id) return Boolean; - -- These functions check to see if the named check is suppressed, - -- either by an active scope suppress setting, or because the check - -- has been specifically suppressed for the given entity. If no entity - -- is relevant for the current check, then Empty is used as an argument. - -- Note: the reason we insist on specifying Empty is to force the - -- caller to think about whether there is any relevant entity that - -- should be checked. - - -- General note on following checks. These checks are always active if - -- Expander_Active and not Inside_A_Generic. They are inactive and have - -- no effect Inside_A_Generic. In the case where not Expander_Active - -- and not Inside_A_Generic, most of them are inactive, but some of them - -- operate anyway since they may generate useful compile time warnings. - - procedure Apply_Access_Check (N : Node_Id); - -- Determines whether an expression node should be flagged as needing - -- a runtime access check. If the node requires such a check, the - -- Do_Access_Check flag is turned on. - - procedure Apply_Accessibility_Check (N : Node_Id; Typ : Entity_Id); - -- Given a name N denoting an access parameter, emits a run-time - -- accessibility check (if necessary), checking that the level of - -- the object denoted by the access parameter is not deeper than the - -- level of the type Typ. Program_Error is raised if the check fails. - - procedure Apply_Alignment_Check (E : Entity_Id; N : Node_Id); - -- E is the entity for an object. If there is an address clause for - -- this entity, and checks are enabled, then this procedure generates - -- a check that the specified address has an alignment consistent with - -- the alignment of the object, raising PE if this is not the case. The - -- resulting check (if one is generated) is inserted before node N. - - procedure Apply_Array_Size_Check (N : Node_Id; Typ : Entity_Id); - -- N is the node for an object declaration that declares an object of - -- array type Typ. This routine generates, if necessary, a check that - -- the size of the array is not too large, raising Storage_Error if so. - - procedure Apply_Arithmetic_Overflow_Check (N : Node_Id); - -- Given a binary arithmetic operator (+ - *) expand a software integer - -- overflow check using range checks on a larger checking type or a call - -- to an appropriate runtime routine. This is used for all three operators - -- for the signed integer case, and for +/- in the fixed-point case. The - -- check is expanded only if Software_Overflow_Checking is enabled and - -- Do_Overflow_Check is set on node N. Note that divide is handled - -- separately using Apply_Arithmetic_Divide_Overflow_Check. - - procedure Apply_Constraint_Check - (N : Node_Id; - Typ : Entity_Id; - No_Sliding : Boolean := False); - -- Top-level procedure, calls all the others depending on the class of Typ. - -- Checks that expression N verifies the constraint of type Typ. No_Sliding - -- is only relevant for constrained array types, id set to true, it - -- checks that indexes are in range. - - procedure Apply_Discriminant_Check - (N : Node_Id; - Typ : Entity_Id; - Lhs : Node_Id := Empty); - -- Given an expression N of a discriminated type, or of an access type - -- whose designated type is a discriminanted type, generates a check to - -- ensure that the expression can be converted to the subtype given as - -- the second parameter. Lhs is empty except in the case of assignments, - -- where the target object may be needed to determine the subtype to - -- check against (such as the cases of unconstrained formal parameters - -- and unconstrained aliased objects). For the case of unconstrained - -- formals, the check is peformed only if the corresponding actual is - -- constrained, i.e., whether Lhs'Constrained is True. - - function Build_Discriminant_Checks - (N : Node_Id; - T_Typ : Entity_Id) - return Node_Id; - -- Subsidiary routine for Apply_Discriminant_Check. Builds the expression - -- that compares discriminants of the expression with discriminants of the - -- type. Also used directly for membership tests (see Exp_Ch4.Expand_N_In). - - procedure Apply_Divide_Check (N : Node_Id); - -- The node kind is N_Op_Divide, N_Op_Mod, or N_Op_Rem. An appropriate - -- check is generated to ensure that the right operand is non-zero. In - -- the divide case, we also check that we do not have the annoying case - -- of the largest negative number divided by minus one. - - procedure Apply_Type_Conversion_Checks (N : Node_Id); - -- N is an N_Type_Conversion node. A type conversion actually involves - -- two sorts of checks. The first check is the checks that ensures that - -- the operand in the type conversion fits onto the base type of the - -- subtype it is being converted to (see RM 4.6 (28)-(50)). The second - -- check is there to ensure that once the operand has been converted to - -- a value of the target type, this converted value meets the - -- constraints imposed by the target subtype (see RM 4.6 (51)). - - procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id); - -- The argument N is an attribute reference node intended for processing - -- by gigi. The attribute is one that returns a universal integer, but - -- the attribute reference node is currently typed with the expected - -- result type. This routine deals with range and overflow checks needed - -- to make sure that the universal result is in range. - - procedure Determine_Range - (N : Node_Id; - 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. - - ----------------------------- - -- Length and Range Checks -- - ----------------------------- - - -- In the following procedures, there are three arguments which have - -- a common meaning as follows: - - -- Expr The expression to be checked. If a check is required, - -- the appropriate flag will be placed on this node. Whether - -- this node is further examined depends on the setting of - -- the parameter Source_Typ, as described below. - - -- Target_Typ The target type on which the check is to be based. For - -- example, if we have a scalar range check, then the check - -- is that we are in range of this type. - - -- Source_Typ Normally Empty, but can be set to a type, in which case - -- this type is used for the check, see below. - - -- 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 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 - -- on return (the Out direction), the types must be reversed. This is - -- handled by the caller. - - procedure Apply_Length_Check - (Ck_Node : Node_Id; - Target_Typ : Entity_Id; - Source_Typ : Entity_Id := Empty); - -- This procedure builds a sequence of declarations to do a length check - -- that checks if the lengths of the two arrays Target_Typ and source type - -- are the same. The resulting actions are inserted at Node using a call - -- to Insert_Actions. - -- - -- For access types, the Directly_Designated_Type is retrieved and - -- 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 - -- processes it as described above for consistency with the other routines - -- in this section. - - procedure Apply_Range_Check - (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 scalar types, constructs a range check action that first tests that - -- the expression is contained in the Target_Typ range. The difference - -- between this and Apply_Scalar_Range_Check is that the latter generates - -- the actual checking code in gigi against the Etype of the expression. - -- - -- For constrained array types, construct series of range check actions - -- 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 access types, the Directly_Designated_Type is retrieved and - -- 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. - - procedure Apply_Static_Length_Check - (Expr : Node_Id; - Target_Typ : Entity_Id; - Source_Typ : Entity_Id := Empty); - -- Tries to determine statically whether the two array types source type - -- and Target_Typ have the same length. If it can be determined at compile - -- time that they do not, then an N_Raise_Constraint_Error node replaces - -- Expr, and a warning message is issued. - - procedure Apply_Scalar_Range_Check - (Expr : Node_Id; - Target_Typ : Entity_Id; - 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). - - type Check_Result is private; - -- Type used to return result of Range_Check call, for later use in - -- call to Insert_Range_Checks procedure. - - procedure Append_Range_Checks - (Checks : Check_Result; - Stmts : List_Id; - Suppress_Typ : Entity_Id; - 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. - - procedure Enable_Range_Check (N : Node_Id); - pragma Inline (Enable_Range_Check); - -- Set Do_Range_Check flag in node N to True unless Kill_Range_Check flag - -- is set in N (the purpose of the latter flag is precisely to prevent - -- Do_Range_Check from being set). - - procedure Insert_Range_Checks - (Checks : Check_Result; - Node : Node_Id; - Suppress_Typ : Entity_Id; - Static_Sloc : Source_Ptr := No_Location; - Flag_Node : Node_Id := Empty; - Do_Before : Boolean := False); - -- Called to insert range checks as returned by a call to Range_Check. - -- Node is the node after which either the dynamic check is inserted or - -- the raise Constraint_Error statement is inserted (for static checks). - -- Suppress_Typ is the type to check to determine if checks are suppressed. - -- Static_Sloc, if passed, is the Sloc at which the raise CE node points, - -- otherwise Sloc (Node) is used. The Has_Dynamic_Check flag is normally - -- set at Node. If Flag_Node is present, then this is used instead as the - -- node at which to set the Has_Dynamic_Check flag. Normally the check is - -- inserted after, if Do_Before is True, the check is inserted before - -- Node. - - function Range_Check - (Ck_Node : Node_Id; - Target_Typ : Entity_Id; - Source_Typ : Entity_Id := Empty; - Warn_Node : Node_Id := Empty) - return Check_Result; - -- Like Apply_Range_Check, except it does not modify anything. Instead - -- it returns an encapsulated result of the check operations for later - -- use in a call to Insert_Range_Checks. If Warn_Node is non-empty, its - -- Sloc is used, in the static case, for the generated warning or error. - -- Additionally, it is used rather than Expr (or Low/High_Bound of Expr) - -- in constructing the check. - - ----------------------- - -- Validity Checking -- - ----------------------- - - -- In (RM 13.9.1(9-11)) we have the following rules on invalid values - - -- 9 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: - -- - -- 10 If the representation of the object represents a value of the - -- object's type, the value of the type is used. - -- - -- 11 If the representation of the object does not represent a value - -- of the object's type, the semantics of operations on such - -- representations is implementation-defined, but does not by - -- itself lead to erroneous or unpredictable execution, or to - -- other objects becoming abnormal. - - -- We quote the rules in full here since they are quite delicate. Most - -- of the time, we can just compute away with wrong values, and get a - -- possibly wrong result, which is well within the range of allowed - -- implementation defined behavior. The two tricky cases are subscripted - -- 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: - - -- None (no validity checking) - - -- In this mode, there is no specific checking for invalid values - -- and the code generator assumes that all stored values are always - -- within the bounds of the object subtype. The consequences are as - -- follows: - - -- For case statements, an out of range invalid value will cause - -- Constraint_Error to be raised, or an arbitrary one of the case - -- alternatives will be executed. Wild jumps cannot result even - -- in this mode, since we always do a range check - - -- For subscripted array assignments, wild stores will result in - -- the expected manner when addresses are calculated using values - -- of subscripts that are out of range. - - -- It could perhaps be argued that this mode is still conformant with - -- the letter of the RM, since implementation defined is a rather - -- broad category, but certainly it is not in the spirit of the - -- RM requirement, since wild stores certainly seem to be a case of - -- erroneous behavior. - - -- Default (default standard RM-compatible validity checking) - - -- In this mode, which is the default, minimal validity checking is - -- performed to ensure no erroneous behavior as follows: - - -- For case statements, an out of range invalid value will cause - -- Constraint_Error to be raised. - - -- For subscripted array assignments, invalid out of range - -- subscript values will cause Constraint_Error to be raised. - - -- Full (Full validity checking) - - -- In this mode, the protections guaranteed by the standard mode are - -- in place, and the following additional checks are made: - - -- For every assignment, the right side is checked for validity - - -- For every call, IN and IN OUT parameters are checked for validity - - -- For every subscripted array reference, both for stores and loads, - -- all subscripts are checked for validity. - - -- These checks are not required by the RM, but will in practice - -- improve the detection of uninitialized variables, particularly - -- if used in conjunction with pragma Normalize_Scalars. - - -- In the above description, we talk about performing validity checks, - -- but we don't actually generate a check in a case where the compiler - -- can be sure that the value is valid. Note that this assurance must - -- be achieved without assuming that any uninitialized value lies within - -- the range of its type. The following are cases in which values are - -- known to be valid. The flag Is_Known_Valid is used to keep track of - -- some of these cases. - - -- If all possible stored values are valid, then any uninitialized - -- value must be valid. - - -- Literals, including enumeration literals, are clearly always valid. - - -- Constants are always assumed valid, with a validity check being - -- performed on the initializing value where necessary to ensure that - -- this is the case. - - -- For variables, the status is set to known valid if there is an - -- initializing expression. Again a check is made on the initializing - -- value if necessary to ensure that this assumption is valid. The - -- status can change as a result of local assignments to a variable. - -- If a known valid value is unconditionally assigned, then we mark - -- the left side as known valid. If a value is assigned that is not - -- known to be valid, then we mark the left side as invalid. This - -- kind of processing does NOT apply to non-local variables since we - -- are not following the flow graph (more properly the flow of actual - -- processing only corresponds to the flow graph for local assignments). - -- For non-local variables, we preserve the current setting, i.e. a - -- validity check is performed when assigning to a knonwn valid global. - - -- Note: no validity checking is required if range checks are suppressed - -- regardless of the setting of the validity checking mode. - - -- The following procedures are used in handling validity checking - - procedure Apply_Subscript_Validity_Checks (Expr : Node_Id); - -- Expr is the node for an indexed component. If validity checking and - -- range checking are enabled, all subscripts for this indexed component - -- 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. - - procedure Ensure_Valid (Expr : Node_Id; Holes_OK : Boolean := False); - -- Ensure that Expr represents a valid value of its type. If this type - -- is not a scalar type, then the call has no effect, since validity - -- is only an issue for scalar types. The effect of this call is to - -- check if the value is known valid, if so, nothing needs to be done. - -- If this is not known, then either Expr is set to be range checked, - -- or specific checking code is inserted so that an exception is raised - -- if the value is not valid. - -- - -- The optional argument Holes_OK indicates whether it is necessary to - -- worry about enumeration types with non-standard representations leading - -- to "holes" in the range of possible representations. If Holes_OK is - -- True, then such values are assumed valid (this is used when the caller - -- will make a separate check for this case anyway). If Holes_OK is False, - -- then this case is checked, and code is inserted to ensure that Expr 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. - - procedure Insert_Valid_Check (Expr : Node_Id); - -- Inserts code that will check for the value of Expr being valid, in - -- the sense of the 'Valid attribute returning True. Constraint_Error - -- will be raised if the value is not valid. - -private - - type Check_Result is array (Positive range 1 .. 2) of Node_Id; - -- There are two cases for the result returned by Range_Check: - -- - -- For the static case the result is one or two nodes that should cause - -- a Constraint_Error. Typically these will include Expr itself or the - -- direct descendents of Expr, such as Low/High_Bound (Expr)). It is the - -- 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. - -- - -- 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 (Access_Checks_Suppressed); - pragma Inline (Accessibility_Checks_Suppressed); - pragma Inline (Discriminant_Checks_Suppressed); - pragma Inline (Division_Checks_Suppressed); - pragma Inline (Elaboration_Checks_Suppressed); - pragma Inline (Index_Checks_Suppressed); - pragma Inline (Length_Checks_Suppressed); - pragma Inline (Overflow_Checks_Suppressed); - pragma Inline (Range_Checks_Suppressed); - pragma Inline (Storage_Checks_Suppressed); - pragma Inline (Tag_Checks_Suppressed); - - pragma Inline (Apply_Length_Check); - pragma Inline (Apply_Range_Check); - pragma Inline (Apply_Static_Length_Check); -end Checks;