-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2016, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2020, 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- --
with Atree; use Atree;
with Checks; use Checks;
with Einfo; use Einfo;
+with Exp_Attr;
+with Exp_Ch4;
with Exp_Ch5; use Exp_Ch5;
with Exp_Dbug; use Exp_Dbug;
with Exp_Util; use Exp_Util;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Rtsfind; use Rtsfind;
+with Sem; use Sem;
+with Sem_Ch8; use Sem_Ch8;
+with Sem_Prag; use Sem_Prag;
with Sem_Res; use Sem_Res;
with Sem_Util; use Sem_Util;
with Sinfo; use Sinfo;
with Snames; use Snames;
+with Stand; use Stand;
with Tbuild; use Tbuild;
-with Uintp; use Uintp;
-with Sem_Eval; use Sem_Eval;
-with Stand; use Stand;
+with Uintp; use Uintp;
package body Exp_SPARK is
-- Local Subprograms --
-----------------------
- procedure Expand_SPARK_Attribute_Reference (N : Node_Id);
- -- Replace occurrences of System'To_Address by calls to
- -- System.Storage_Elements.To_Address
+ procedure Expand_SPARK_N_Attribute_Reference (N : Node_Id);
+ -- Perform attribute-reference-specific expansion
+
+ procedure Expand_SPARK_N_Delta_Aggregate (N : Node_Id);
+ -- Perform delta-aggregate-specific expansion
+
+ procedure Expand_SPARK_N_Freeze_Type (E : Entity_Id);
+ -- Build the DIC procedure of a type when needed, if not already done
+
+ procedure Expand_SPARK_N_Loop_Statement (N : Node_Id);
+ -- Perform loop-statement-specific expansion
+
+ procedure Expand_SPARK_N_Object_Declaration (N : Node_Id);
+ -- Perform object-declaration-specific expansion
procedure Expand_SPARK_N_Object_Renaming_Declaration (N : Node_Id);
-- Perform name evaluation for a renamed object
+ procedure Expand_SPARK_N_Op_Ne (N : Node_Id);
+ -- Rewrite operator /= based on operator = when defined explicitly
+
+ procedure Expand_SPARK_Delta_Or_Update (Typ : Entity_Id; Aggr : Node_Id);
+ -- Common expansion for attribute Update and delta aggregates
+
------------------
-- Expand_SPARK --
------------------
=>
Qualify_Entity_Names (N);
+ -- Replace occurrences of System'To_Address by calls to
+ -- System.Storage_Elements.To_Address.
+
+ when N_Attribute_Reference =>
+ Expand_SPARK_N_Attribute_Reference (N);
+
+ when N_Delta_Aggregate =>
+ Expand_SPARK_N_Delta_Aggregate (N);
+
when N_Expanded_Name
| N_Identifier
=>
Expand_SPARK_Potential_Renaming (N);
- when N_Object_Renaming_Declaration =>
- Expand_SPARK_N_Object_Renaming_Declaration (N);
-
- -- Replace occurrences of System'To_Address by calls to
- -- System.Storage_Elements.To_Address
-
- when N_Attribute_Reference =>
- Expand_SPARK_Attribute_Reference (N);
-
-- Loop iterations over arrays need to be expanded, to avoid getting
-- two names referring to the same object in memory (the array and
-- the iterator) in GNATprove, especially since both can be written
-- dealt with specially in GNATprove.
when N_Loop_Statement =>
- declare
- Scheme : constant Node_Id := Iteration_Scheme (N);
- begin
- if Present (Scheme)
- and then Present (Iterator_Specification (Scheme))
- and then
- Is_Iterator_Over_Array (Iterator_Specification (Scheme))
- then
- Expand_Iterator_Loop_Over_Array (N);
- end if;
- end;
+ Expand_SPARK_N_Loop_Statement (N);
+
+ when N_Object_Declaration =>
+ Expand_SPARK_N_Object_Declaration (N);
+
+ when N_Object_Renaming_Declaration =>
+ Expand_SPARK_N_Object_Renaming_Declaration (N);
+
+ when N_Op_Ne =>
+ Expand_SPARK_N_Op_Ne (N);
+
+ when N_Freeze_Entity =>
+ if Is_Type (Entity (N)) then
+ Expand_SPARK_N_Freeze_Type (Entity (N));
+ end if;
-- In SPARK mode, no other constructs require expansion
end case;
end Expand_SPARK;
- --------------------------------------
- -- Expand_SPARK_Attribute_Reference --
- --------------------------------------
+ ----------------------------------
+ -- Expand_SPARK_Delta_Or_Update --
+ ----------------------------------
+
+ procedure Expand_SPARK_Delta_Or_Update
+ (Typ : Entity_Id;
+ Aggr : Node_Id)
+ is
+ Assoc : Node_Id;
+ Comp : Node_Id;
+ Comp_Id : Entity_Id;
+ Comp_Type : Entity_Id;
+ Expr : Node_Id;
+ Index : Node_Id;
+ Index_Typ : Entity_Id;
+ New_Assoc : Node_Id;
+
+ begin
+ -- Apply scalar range checks on the updated components, if needed
+
+ if Is_Array_Type (Typ) then
+
+ -- Multidimensional arrays
- procedure Expand_SPARK_Attribute_Reference (N : Node_Id) is
+ if Present (Next_Index (First_Index (Typ))) then
+ Assoc := First (Component_Associations (Aggr));
+
+ while Present (Assoc) loop
+ Expr := Expression (Assoc);
+ Comp_Type := Component_Type (Typ);
+
+ if Is_Scalar_Type (Comp_Type) then
+ Apply_Scalar_Range_Check (Expr, Comp_Type);
+ end if;
+
+ -- The current association contains a sequence of indexes
+ -- denoting an element of a multidimensional array:
+ --
+ -- (Index_1, ..., Index_N)
+
+ Expr := First (Choices (Assoc));
+
+ pragma Assert (Nkind (Aggr) = N_Aggregate);
+
+ while Present (Expr) loop
+ Index := First (Expressions (Expr));
+ Index_Typ := First_Index (Typ);
+
+ while Present (Index_Typ) loop
+ Apply_Scalar_Range_Check (Index, Etype (Index_Typ));
+ Next (Index);
+ Next_Index (Index_Typ);
+ end loop;
+
+ Next (Expr);
+ end loop;
+
+ Next (Assoc);
+ end loop;
+
+ -- One-dimensional arrays
+
+ else
+ Assoc := First (Component_Associations (Aggr));
+
+ while Present (Assoc) loop
+ Expr := Expression (Assoc);
+ Comp_Type := Component_Type (Typ);
+
+ -- Analyze expression of the iterated_component_association
+ -- with its index parameter in scope.
+
+ if Nkind (Assoc) = N_Iterated_Component_Association then
+ Push_Scope (Scope (Defining_Identifier (Assoc)));
+ Enter_Name (Defining_Identifier (Assoc));
+ Analyze_And_Resolve (Expr, Comp_Type);
+ end if;
+
+ if Is_Scalar_Type (Comp_Type) then
+ Apply_Scalar_Range_Check (Expr, Comp_Type);
+ end if;
+
+ -- Restore scope of the iterated_component_association
+
+ if Nkind (Assoc) = N_Iterated_Component_Association then
+ End_Scope;
+ end if;
+
+ Index := First (Choice_List (Assoc));
+ Index_Typ := First_Index (Typ);
+
+ while Present (Index) loop
+ -- If the index denotes a range of elements or a constrained
+ -- subtype indication, then their low and high bounds
+ -- already have range checks applied.
+
+ if Nkind (Index) in N_Range | N_Subtype_Indication then
+ null;
+
+ -- Otherwise the index denotes a single expression where
+ -- range checks need to be applied or a subtype name
+ -- (without range constraints) where applying checks is
+ -- harmless.
+ --
+ -- In delta_aggregate and Update attribute on array the
+ -- others_choice is not allowed.
+
+ else pragma Assert (Nkind (Index) in N_Subexpr);
+ Apply_Scalar_Range_Check (Index, Etype (Index_Typ));
+ end if;
+
+ Next (Index);
+ end loop;
+
+ Next (Assoc);
+ end loop;
+ end if;
+
+ else pragma Assert (Is_Record_Type (Typ));
+
+ -- If the aggregate has multiple component choices, e.g.:
+ --
+ -- X'Update (A | B | C => 123)
+ --
+ -- then each component might be of a different type and might or
+ -- might not require a range check. We first rewrite associations
+ -- into single-component choices, e.g.:
+ --
+ -- X'Update (A => 123, B => 123, C => 123)
+ --
+ -- and then apply range checks to individual copies of the
+ -- expressions. We do the same for delta aggregates, accordingly.
+
+ -- Iterate over associations of the original aggregate
+
+ Assoc := First (Component_Associations (Aggr));
+
+ -- Rewrite into a new aggregate and decorate
+
+ case Nkind (Aggr) is
+ when N_Aggregate =>
+ Rewrite
+ (Aggr,
+ Make_Aggregate
+ (Sloc => Sloc (Aggr),
+ Component_Associations => New_List));
+
+ when N_Delta_Aggregate =>
+ Rewrite
+ (Aggr,
+ Make_Delta_Aggregate
+ (Sloc => Sloc (Aggr),
+ Expression => Expression (Aggr),
+ Component_Associations => New_List));
+
+ when others =>
+ raise Program_Error;
+ end case;
+
+ Set_Etype (Aggr, Typ);
+
+ -- Populate the new aggregate with component associations
+
+ while Present (Assoc) loop
+ Expr := Expression (Assoc);
+ Comp := First (Choices (Assoc));
+
+ while Present (Comp) loop
+ Comp_Id := Entity (Comp);
+ Comp_Type := Etype (Comp_Id);
+
+ New_Assoc :=
+ Make_Component_Association
+ (Sloc => Sloc (Assoc),
+ Choices =>
+ New_List
+ (New_Occurrence_Of (Comp_Id, Sloc (Comp))),
+ Expression => New_Copy_Tree (Expr));
+
+ -- New association must be attached to the aggregate before we
+ -- analyze it.
+
+ Append (New_Assoc, Component_Associations (Aggr));
+
+ Analyze_And_Resolve (Expression (New_Assoc), Comp_Type);
+
+ if Is_Scalar_Type (Comp_Type) then
+ Apply_Scalar_Range_Check
+ (Expression (New_Assoc), Comp_Type);
+ end if;
+
+ Next (Comp);
+ end loop;
+
+ Next (Assoc);
+ end loop;
+ end if;
+ end Expand_SPARK_Delta_Or_Update;
+
+ --------------------------------
+ -- Expand_SPARK_N_Freeze_Type --
+ --------------------------------
+
+ procedure Expand_SPARK_N_Freeze_Type (E : Entity_Id) is
+ begin
+ -- When a DIC is inherited by a tagged type, it may need to be
+ -- specialized to the descendant type, hence build a separate DIC
+ -- procedure for it as done during regular expansion for compilation.
+
+ if Has_DIC (E) and then Is_Tagged_Type (E) then
+ Build_DIC_Procedure_Body (E, For_Freeze => True);
+ end if;
+ end Expand_SPARK_N_Freeze_Type;
+
+ ----------------------------------------
+ -- Expand_SPARK_N_Attribute_Reference --
+ ----------------------------------------
+
+ procedure Expand_SPARK_N_Attribute_Reference (N : Node_Id) is
Aname : constant Name_Id := Attribute_Name (N);
Attr_Id : constant Attribute_Id := Get_Attribute_Id (Aname);
Loc : constant Source_Ptr := Sloc (N);
+ Pref : constant Node_Id := Prefix (N);
Typ : constant Entity_Id := Etype (N);
Expr : Node_Id;
Parameter_Associations => New_List (Expr)));
Analyze_And_Resolve (N, Typ);
+ elsif Attr_Id = Attribute_Object_Size
+ or else Attr_Id = Attribute_Size
+ or else Attr_Id = Attribute_Value_Size
+ or else Attr_Id = Attribute_VADS_Size
+ then
+ Exp_Attr.Expand_Size_Attribute (N);
+
-- For attributes which return Universal_Integer, introduce a conversion
-- to the expected type with the appropriate check flags set.
or else Attr_Id = Attribute_Pos
or else Attr_Id = Attribute_Position
or else Attr_Id = Attribute_Range_Length
- or else Attr_Id = Attribute_Object_Size
- or else Attr_Id = Attribute_Size
- or else Attr_Id = Attribute_Value_Size
- or else Attr_Id = Attribute_VADS_Size
or else Attr_Id = Attribute_Aft
or else Attr_Id = Attribute_Max_Alignment_For_Allocation
then
-
-- If the expected type is Long_Long_Integer, there will be no check
-- flag as the compiler assumes attributes always fit in this type.
-- Since in SPARK_Mode we do not take Storage_Error into account, we
-- cannot make this assumption and need to produce a check.
- -- ??? It should be enough to add this check for attributes 'Length
- -- and 'Range_Length when the type is as big as Long_Long_Integer.
+ -- ??? It should be enough to add this check for attributes
+ -- 'Length, 'Range_Length and 'Pos when the type is as big
+ -- as Long_Long_Integer.
declare
- Typ : Entity_Id := Empty;
+ Typ : Entity_Id;
begin
- if Attr_Id = Attribute_Range_Length then
- Typ := Etype (Prefix (N));
- elsif Attr_Id = Attribute_Length then
+ if Attr_Id = Attribute_Range_Length
+ or else Attr_Id = Attribute_Pos
+ then
Typ := Etype (Prefix (N));
- declare
- Indx : Node_Id;
- J : Int;
- begin
- if Is_Access_Type (Typ) then
- Typ := Designated_Type (Typ);
- end if;
-
- if No (Expressions (N)) then
- J := 1;
- else
- J := UI_To_Int (Expr_Value (First (Expressions (N))));
- end if;
-
- Indx := First_Index (Typ);
- while J > 1 loop
- Next_Index (Indx);
- J := J - 1;
- end loop;
+ elsif Attr_Id = Attribute_Length then
+ Typ := Get_Index_Subtype (N);
- Typ := Etype (Indx);
- end;
+ else
+ Typ := Empty;
end if;
Apply_Universal_Integer_Attribute_Checks (N);
if Present (Typ)
and then RM_Size (Typ) = RM_Size (Standard_Long_Long_Integer)
then
+ -- ??? This should rather be a range check, but this would
+ -- crash GNATprove which somehow recovers the proper kind
+ -- of check anyway.
Set_Do_Overflow_Check (N);
end if;
end;
+
+ elsif Attr_Id = Attribute_Constrained then
+
+ -- If the prefix is an access to object, the attribute applies to
+ -- the designated object, so rewrite with an explicit dereference.
+
+ if Is_Access_Type (Etype (Pref))
+ and then
+ (not Is_Entity_Name (Pref) or else Is_Object (Entity (Pref)))
+ then
+ Rewrite (Pref,
+ Make_Explicit_Dereference (Loc, Relocate_Node (Pref)));
+ Analyze_And_Resolve (N, Standard_Boolean);
+ end if;
+
+ elsif Attr_Id = Attribute_Update then
+ Expand_SPARK_Delta_Or_Update (Typ, First (Expressions (N)));
+ end if;
+ end Expand_SPARK_N_Attribute_Reference;
+
+ ------------------------------------
+ -- Expand_SPARK_N_Delta_Aggregate --
+ ------------------------------------
+
+ procedure Expand_SPARK_N_Delta_Aggregate (N : Node_Id) is
+ begin
+ Expand_SPARK_Delta_Or_Update (Etype (N), N);
+ end Expand_SPARK_N_Delta_Aggregate;
+
+ -----------------------------------
+ -- Expand_SPARK_N_Loop_Statement --
+ -----------------------------------
+
+ procedure Expand_SPARK_N_Loop_Statement (N : Node_Id) is
+ Scheme : constant Node_Id := Iteration_Scheme (N);
+
+ begin
+ -- Loop iterations over arrays need to be expanded, to avoid getting
+ -- two names referring to the same object in memory (the array and the
+ -- iterator) in GNATprove, especially since both can be written (thus
+ -- possibly leading to interferences due to aliasing). No such problem
+ -- arises with quantified expressions over arrays, which are dealt with
+ -- specially in GNATprove.
+
+ if Present (Scheme)
+ and then Present (Iterator_Specification (Scheme))
+ and then Is_Iterator_Over_Array (Iterator_Specification (Scheme))
+ then
+ Expand_Iterator_Loop_Over_Array (N);
+ end if;
+ end Expand_SPARK_N_Loop_Statement;
+
+ ---------------------------------------
+ -- Expand_SPARK_N_Object_Declaration --
+ ---------------------------------------
+
+ procedure Expand_SPARK_N_Object_Declaration (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+ Obj_Id : constant Entity_Id := Defining_Identifier (N);
+ Typ : constant Entity_Id := Etype (Obj_Id);
+
+ Call : Node_Id;
+
+ begin
+ -- If the object declaration denotes a variable without initialization
+ -- whose type is subject to pragma Default_Initial_Condition, create
+ -- and analyze a dummy call to the DIC procedure of the type in order
+ -- to detect potential elaboration issues.
+
+ if Comes_From_Source (Obj_Id)
+ and then Ekind (Obj_Id) = E_Variable
+ and then Has_DIC (Typ)
+ and then Present (DIC_Procedure (Typ))
+ and then not Has_Init_Expression (N)
+ then
+ Call := Build_DIC_Call (Loc, Obj_Id, Typ);
+
+ -- Partially insert the call into the tree by setting its parent
+ -- pointer.
+
+ Set_Parent (Call, N);
+ Analyze (Call);
end if;
- end Expand_SPARK_Attribute_Reference;
+ end Expand_SPARK_N_Object_Declaration;
------------------------------------------------
-- Expand_SPARK_N_Object_Renaming_Declaration --
------------------------------------------------
procedure Expand_SPARK_N_Object_Renaming_Declaration (N : Node_Id) is
+ CFS : constant Boolean := Comes_From_Source (N);
+ Loc : constant Source_Ptr := Sloc (N);
+ Obj_Id : constant Entity_Id := Defining_Entity (N);
+ Nam : constant Node_Id := Name (N);
+ Typ : constant Entity_Id := Etype (Obj_Id);
+
begin
- -- Unconditionally remove all side effects from the name
+ -- Transform a renaming of the form
+
+ -- Obj_Id : <subtype mark> renames <function call>;
+
+ -- into
+
+ -- Obj_Id : constant <subtype mark> := <function call>;
+
+ -- Invoking Evaluate_Name and ultimately Remove_Side_Effects introduces
+ -- a temporary to capture the function result. Once potential renamings
+ -- are rewritten for SPARK, the temporary may be leaked out into source
+ -- constructs and lead to confusing error diagnostics. Using an object
+ -- declaration prevents this unwanted side effect.
+
+ if Nkind (Nam) = N_Function_Call then
+ Rewrite (N,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Obj_Id,
+ Constant_Present => True,
+ Object_Definition => New_Occurrence_Of (Typ, Loc),
+ Expression => Nam));
+
+ -- Inherit the original Comes_From_Source status of the renaming
+
+ Set_Comes_From_Source (N, CFS);
- Evaluate_Name (Name (N));
+ -- Sever the link to the renamed function result because the entity
+ -- will no longer alias anything.
+
+ Set_Renamed_Object (Obj_Id, Empty);
+
+ -- Remove the entity of the renaming declaration from visibility as
+ -- the analysis of the object declaration will reintroduce it again.
+
+ Remove_Entity_And_Homonym (Obj_Id);
+ Analyze (N);
+
+ -- Otherwise unconditionally remove all side effects from the name
+
+ else
+ Evaluate_Name (Nam);
+ end if;
end Expand_SPARK_N_Object_Renaming_Declaration;
+ --------------------------
+ -- Expand_SPARK_N_Op_Ne --
+ --------------------------
+
+ procedure Expand_SPARK_N_Op_Ne (N : Node_Id) is
+ Typ : constant Entity_Id := Etype (Left_Opnd (N));
+
+ begin
+ -- Case of elementary type with standard operator
+
+ if Is_Elementary_Type (Typ)
+ and then Sloc (Entity (N)) = Standard_Location
+ then
+ null;
+
+ else
+ Exp_Ch4.Expand_N_Op_Ne (N);
+ end if;
+ end Expand_SPARK_N_Op_Ne;
+
-------------------------------------
-- Expand_SPARK_Potential_Renaming --
-------------------------------------
procedure Expand_SPARK_Potential_Renaming (N : Node_Id) is
+ function In_Insignificant_Pragma (Nod : Node_Id) return Boolean;
+ -- Determine whether arbitrary node Nod appears within a significant
+ -- pragma for SPARK.
+
+ -----------------------------
+ -- In_Insignificant_Pragma --
+ -----------------------------
+
+ function In_Insignificant_Pragma (Nod : Node_Id) return Boolean is
+ Par : Node_Id;
+
+ begin
+ -- Climb the parent chain looking for an enclosing pragma
+
+ Par := Nod;
+ while Present (Par) loop
+ if Nkind (Par) = N_Pragma then
+ return not Pragma_Significant_In_SPARK (Get_Pragma_Id (Par));
+
+ -- Prevent the search from going too far
+
+ elsif Is_Body_Or_Package_Declaration (Par) then
+ exit;
+ end if;
+
+ Par := Parent (Par);
+ end loop;
+
+ return False;
+ end In_Insignificant_Pragma;
+
+ -- Local variables
+
Loc : constant Source_Ptr := Sloc (N);
- Ren_Id : constant Entity_Id := Entity (N);
+ Obj_Id : constant Entity_Id := Entity (N);
Typ : constant Entity_Id := Etype (N);
- Obj_Id : Node_Id;
+ Ren : Node_Id;
+
+ -- Start of processing for Expand_SPARK_Potential_Renaming
begin
-- Replace a reference to a renaming with the actual renamed object
- if Ekind (Ren_Id) in Object_Kind then
- Obj_Id := Renamed_Object (Ren_Id);
+ if Is_Object (Obj_Id) then
+ Ren := Renamed_Object (Obj_Id);
+
+ if Present (Ren) then
+
+ -- Do not process a reference when it appears within a pragma of
+ -- no significance to SPARK. It is assumed that the replacement
+ -- will violate the semantics of the pragma and cause a spurious
+ -- error.
- if Present (Obj_Id) then
+ if In_Insignificant_Pragma (N) then
+ return;
- -- The renamed object is an entity when instantiating generics
- -- or inlining bodies. In this case the renaming is part of the
- -- mapping "prologue" which links actuals to formals.
+ -- Instantiations and inlining of subprograms employ "prologues"
+ -- which map actual to formal parameters by means of renamings.
+ -- Replace a reference to a formal by the corresponding actual
+ -- parameter.
- if Nkind (Obj_Id) in N_Entity then
- Rewrite (N, New_Occurrence_Of (Obj_Id, Loc));
+ elsif Nkind (Ren) in N_Entity then
+ Rewrite (N, New_Occurrence_Of (Ren, Loc));
-- Otherwise the renamed object denotes a name
else
- Rewrite (N, New_Copy_Tree (Obj_Id, New_Sloc => Loc));
+ Rewrite (N, New_Copy_Tree (Ren, New_Sloc => Loc));
Reset_Analyzed_Flags (N);
end if;
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