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Diffstat (limited to 'gcc-4.8.3/gcc/ada/sem_ch13.ads')
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diff --git a/gcc-4.8.3/gcc/ada/sem_ch13.ads b/gcc-4.8.3/gcc/ada/sem_ch13.ads new file mode 100644 index 000000000..611f3f1c6 --- /dev/null +++ b/gcc-4.8.3/gcc/ada/sem_ch13.ads @@ -0,0 +1,325 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S E M _ C H 1 3 -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 1992-2012, 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 3, 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 COPYING3. If not, go to -- +-- http://www.gnu.org/licenses for a complete copy of the license. -- +-- -- +-- GNAT was originally developed by the GNAT team at New York University. -- +-- Extensive contributions were provided by Ada Core Technologies Inc. -- +-- -- +------------------------------------------------------------------------------ + +with Table; +with Types; use Types; +with Uintp; use Uintp; + +package Sem_Ch13 is + procedure Analyze_At_Clause (N : Node_Id); + procedure Analyze_Attribute_Definition_Clause (N : Node_Id); + procedure Analyze_Enumeration_Representation_Clause (N : Node_Id); + procedure Analyze_Free_Statement (N : Node_Id); + procedure Analyze_Freeze_Entity (N : Node_Id); + procedure Analyze_Record_Representation_Clause (N : Node_Id); + procedure Analyze_Code_Statement (N : Node_Id); + + procedure Analyze_Aspect_Specifications (N : Node_Id; E : Entity_Id); + -- This procedure is called to analyze aspect specifications for node N. E + -- is the corresponding entity declared by the declaration node N. Callers + -- should check that Has_Aspects (N) is True before calling this routine. + + procedure Adjust_Record_For_Reverse_Bit_Order (R : Entity_Id); + -- Called from Freeze where R is a record entity for which reverse bit + -- order is specified and there is at least one component clause. Adjusts + -- component positions according to either Ada 95 or Ada 2005 (AI-133). + + function Build_Invariant_Procedure_Declaration + (Typ : Entity_Id) return Node_Id; + -- If a type declaration has a specified invariant aspect, build the + -- declaration for the procedure at once, so that calls to it can be + -- generated before the body of the invariant procedure is built. This + -- is needed in the presence of public expression functions that return + -- the type in question. + + procedure Build_Invariant_Procedure (Typ : Entity_Id; N : Node_Id); + -- Typ is a private type with invariants (indicated by Has_Invariants being + -- set for Typ, indicating the presence of pragma Invariant entries on the + -- rep chain, note that Invariant aspects have already been converted to + -- pragma Invariant), then this procedure builds the spec and body for the + -- corresponding Invariant procedure, inserting them at appropriate points + -- in the package specification N. Invariant_Procedure is set for Typ. Note + -- that this procedure is called at the end of processing the declarations + -- in the visible part (i.e. the right point for visibility analysis of + -- the invariant expression). + + procedure Check_Record_Representation_Clause (N : Node_Id); + -- This procedure completes the analysis of a record representation clause + -- N. It is called at freeze time after adjustment of component clause bit + -- positions for possible non-standard bit order. In the case of Ada 2005 + -- (machine scalar) mode, this adjustment can make substantial changes, so + -- some checks, in particular for component overlaps cannot be done at the + -- time the record representation clause is first seen, but must be delayed + -- till freeze time, and in particular is called after calling the above + -- procedure for adjusting record bit positions for reverse bit order. + + procedure Initialize; + -- Initialize internal tables for new compilation + + procedure Set_Enum_Esize (T : Entity_Id); + -- This routine sets the Esize field for an enumeration type T, based + -- on the current representation information available for T. Note that + -- the setting of the RM_Size field is not affected. This routine also + -- initializes the alignment field to zero. + + function Minimum_Size + (T : Entity_Id; + Biased : Boolean := False) return Nat; + -- Given an elementary type, determines the minimum number of bits required + -- to represent all values of the type. This function may not be called + -- with any other types. If the flag Biased is set True, then the minimum + -- size calculation that biased representation is used in the case of a + -- discrete type, e.g. the range 7..8 gives a minimum size of 4 with + -- Biased set to False, and 1 with Biased set to True. Note that the + -- biased parameter only has an effect if the type is not biased, it + -- causes Minimum_Size to indicate the minimum size of an object with + -- the given type, of the size the type would have if it were biased. If + -- the type is already biased, then Minimum_Size returns the biased size, + -- regardless of the setting of Biased. Also, fixed-point types are never + -- biased in the current implementation. If the size is not known at + -- compile time, this function returns 0. + + procedure Check_Constant_Address_Clause (Expr : Node_Id; U_Ent : Entity_Id); + -- Expr is an expression for an address clause. This procedure checks + -- that the expression is constant, in the limited sense that it is safe + -- to evaluate it at the point the object U_Ent is declared, rather than + -- at the point of the address clause. The condition for this to be true + -- is that the expression has no variables, no constants declared after + -- U_Ent, and no calls to non-pure functions. If this condition is not + -- met, then an appropriate error message is posted. This check is applied + -- at the point an object with an address clause is frozen, as well as for + -- address clauses for tasks and entries. + + procedure Check_Size + (N : Node_Id; + T : Entity_Id; + Siz : Uint; + Biased : out Boolean); + -- Called when size Siz is specified for subtype T. This subprogram checks + -- that the size is appropriate, posting errors on node N as required. + -- This check is effective for elementary types and bit-packed arrays. + -- For other non-elementary types, a check is only made if an explicit + -- size has been given for the type (and the specified size must match). + -- The parameter Biased is set False if the size specified did not require + -- the use of biased representation, and True if biased representation + -- was required to meet the size requirement. Note that Biased is only + -- set if the type is not currently biased, but biasing it is the only + -- way to meet the requirement. If the type is currently biased, then + -- this biased size is used in the initial check, and Biased is False. + -- If the size is too small, and an error message is given, then both + -- Esize and RM_Size are reset to the allowed minimum value in T. + + function Rep_Item_Too_Early (T : Entity_Id; N : Node_Id) return Boolean; + -- Called at the start of processing a representation clause or a + -- representation pragma. Used to check that the representation item + -- is not being applied to an incomplete type or to a generic formal + -- type or a type derived from a generic formal type. Returns False if + -- no such error occurs. If this error does occur, appropriate error + -- messages are posted on node N, and True is returned. + + function Rep_Item_Too_Late + (T : Entity_Id; + N : Node_Id; + FOnly : Boolean := False) return Boolean; + -- Called at the start of processing a representation clause or a + -- representation pragma. Used to check that a representation item + -- for entity T does not appear too late (according to the rules in + -- RM 13.1(9) and RM 13.1(10)). N is the associated node, which in + -- the pragma case is the pragma or representation clause itself, used + -- for placing error messages if the item is too late. + -- + -- Fonly is a flag that causes only the freezing rule (para 9) to be + -- applied, and the tests of para 10 are skipped. This is appropriate + -- for both subtype related attributes (Alignment and Size) and for + -- stream attributes, which, although certainly not subtype related + -- attributes, clearly should not be subject to the para 10 restrictions + -- (see AI95-00137). Similarly, we also skip the para 10 restrictions for + -- the Storage_Size case where they also clearly do not apply, and for + -- Stream_Convert which is in the same category as the stream attributes. + -- + -- If the rep item is too late, an appropriate message is output and + -- True is returned, which is a signal that the caller should abandon + -- processing for the item. If the item is not too late, then False + -- is returned, and the caller can continue processing the item. + -- + -- If no error is detected, this call also as a side effect links the + -- representation item onto the head of the representation item chain + -- (referenced by the First_Rep_Item field of the entity). + -- + -- Note: Rep_Item_Too_Late must be called with the underlying type in + -- the case of a private or incomplete type. The protocol is to first + -- check for Rep_Item_Too_Early using the initial entity, then take the + -- underlying type, then call Rep_Item_Too_Late on the result. + -- + -- Note: Calls to Rep_Item_Too_Late are ignored for the case of attribute + -- definition clauses which have From_Aspect_Specification set. This is + -- because such clauses are linked on to the Rep_Item chain in procedure + -- Sem_Ch13.Analyze_Aspect_Specifications. See that procedure for details. + + function Same_Representation (Typ1, Typ2 : Entity_Id) return Boolean; + -- Given two types, where the two types are related by possible derivation, + -- determines if the two types have the same representation, or different + -- representations, requiring the special processing for representation + -- change. A False result is possible only for array, enumeration or + -- record types. + + procedure Validate_Unchecked_Conversion + (N : Node_Id; + Act_Unit : Entity_Id); + -- Validate a call to unchecked conversion. N is the node for the actual + -- instantiation, which is used only for error messages. Act_Unit is the + -- entity for the instantiation, from which the actual types etc. for this + -- instantiation can be determined. This procedure makes an entry in a + -- table and/or generates an N_Validate_Unchecked_Conversion node. The + -- actual checking is done in Validate_Unchecked_Conversions or in the + -- back end as required. + + procedure Validate_Unchecked_Conversions; + -- This routine is called after calling the backend to validate unchecked + -- conversions for size and alignment appropriateness. The reason it is + -- called that late is to take advantage of any back-annotation of size + -- and alignment performed by the backend. + + procedure Validate_Address_Clauses; + -- This is called after the back end has been called (and thus after the + -- alignments of objects have been back annotated). It goes through the + -- table of saved address clauses checking for suspicious alignments and + -- if necessary issuing warnings. + + procedure Validate_Independence; + -- This is called after the back end has been called (and thus after the + -- layout of components has been back annotated). It goes through the + -- table of saved pragma Independent[_Component] entries, checking that + -- independence can be achieved, and if necessary issuing error messages. + + ------------------------------------- + -- Table for Validate_Independence -- + ------------------------------------- + + -- If a legal pragma Independent or Independent_Components is given for + -- an entity, then an entry is made in this table, to be checked by a + -- call to Validate_Independence after back annotation of layout is done. + + type Independence_Check_Record is record + N : Node_Id; + -- The pragma Independent or Independent_Components + + E : Entity_Id; + -- The entity to which it applies + end record; + + package Independence_Checks is new Table.Table ( + Table_Component_Type => Independence_Check_Record, + Table_Index_Type => Int, + Table_Low_Bound => 1, + Table_Initial => 20, + Table_Increment => 200, + Table_Name => "Independence_Checks"); + + ----------------------------------- + -- Handling of Aspect Visibility -- + ----------------------------------- + + -- The visibility of aspects is tricky. First, the visibility is delayed + -- to the freeze point. This is not too complicated, what we do is simply + -- to leave the aspect "laying in wait" for the freeze point, and at that + -- point materialize and analyze the corresponding attribute definition + -- clause or pragma. There is some special processing for preconditions + -- and postonditions, where the pragmas themselves deal with the required + -- delay, but basically the approach is the same, delay analysis of the + -- expression to the freeze point. + + -- Much harder is the requirement for diagnosing cases in which an early + -- freeze causes a change in visibility. Consider: + + -- package AspectVis is + -- R_Size : constant Integer := 32; + -- + -- package Inner is + -- type R is new Integer with + -- Size => R_Size; + -- F : R; -- freezes + -- R_Size : constant Integer := 64; + -- S : constant Integer := R'Size; -- 32 not 64 + -- end Inner; + -- end AspectVis; + + -- Here the 32 not 64 shows what would be expected if this program were + -- legal, since the evaluation of R_Size has to be done at the freeze + -- point and gets the outer definition not the inner one. + + -- But the language rule requires this program to be diagnosed as illegal + -- because the visibility changes between the freeze point and the end of + -- the declarative region. + + -- To meet this requirement, we first note that the Expression field of the + -- N_Aspect_Specification node holds the raw unanalyzed expression, which + -- will get used in processing the aspect. At the time of analyzing the + -- N_Aspect_Specification node, we create a complete copy of the expression + -- and store it in the entity field of the Identifier (an odd usage, but + -- the identifier is not used except to identify the aspect, so its Entity + -- field is otherwise unused, and we are short of room in the node). + + -- This copy stays unanalyzed up to the freeze point, where we analyze the + -- resulting pragma or attribute definition clause, except that in the + -- case of invariants and predicates, we mark occurrences of the subtype + -- name as having the entity of the subprogram parameter, so that they + -- will not cause trouble in the following steps. + + -- Then at the freeze point, we create another copy of this unanalyzed + -- expression. By this time we no longer need the Expression field for + -- other purposes, so we can store it there. Now we have two copies of + -- the original unanalyzed expression. One of them gets preanalyzed at + -- the freeze point to capture the visibility at the freeze point. + + -- Now when we hit the freeze all at the end of the declarative part, if + -- we come across a frozen entity with delayed aspects, we still have one + -- copy of the unanalyzed expression available in the node, and we again + -- do a preanalysis using that copy and the visibility at the end of the + -- declarative part. Now we have two preanalyzed expression (preanalysis + -- is good enough, since we are only interested in referenced entities). + -- One captures the visibility at the freeze point, the other captures the + -- visibility at the end of the declarative part. We see if the entities + -- in these two expressions are the same, by seeing if the two expressions + -- are fully conformant, and if not, issue appropriate error messages. + + -- Quite an awkward procedure, but this is an awkard requirement! + + procedure Analyze_Aspects_At_Freeze_Point (E : Entity_Id); + -- Analyze all the delayed aspects for entity E at freezing point + + procedure Check_Aspect_At_Freeze_Point (ASN : Node_Id); + -- Performs the processing described above at the freeze point, ASN is the + -- N_Aspect_Specification node for the aspect. + + procedure Check_Aspect_At_End_Of_Declarations (ASN : Node_Id); + -- Performs the processing described above at the freeze all point, and + -- issues appropriate error messages if the visibility has indeed changed. + -- Again, ASN is the N_Aspect_Specification node for the aspect. + + procedure Inherit_Aspects_At_Freeze_Point (Typ : Entity_Id); + -- Given an entity Typ that denotes a derived type or a subtype, this + -- routine performs the inheritance of aspects at the freeze point. +end Sem_Ch13; |