-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2004, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2007, 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- --
-- 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. --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, USA. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
with Atree; use Atree;
with Checks; use Checks;
+with Debug; use Debug;
with Einfo; use Einfo;
+with Elists; use Elists;
+with Exp_Atag; use Exp_Atag;
with Exp_Aggr; use Exp_Aggr;
+with Exp_Ch6; use Exp_Ch6;
with Exp_Ch7; use Exp_Ch7;
with Exp_Ch11; use Exp_Ch11;
with Exp_Dbug; use Exp_Dbug;
with Exp_Pakd; use Exp_Pakd;
with Exp_Tss; use Exp_Tss;
with Exp_Util; use Exp_Util;
-with Hostparm; use Hostparm;
+with Namet; use Namet;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Rtsfind; use Rtsfind;
with Sinfo; use Sinfo;
with Sem; use Sem;
+with Sem_Ch3; use Sem_Ch3;
with Sem_Ch8; use Sem_Ch8;
with Sem_Ch13; use Sem_Ch13;
with Sem_Eval; use Sem_Eval;
with Snames; use Snames;
with Stand; use Stand;
with Stringt; use Stringt;
+with Targparm; use Targparm;
with Tbuild; use Tbuild;
+with Ttypes; use Ttypes;
with Uintp; use Uintp;
with Validsw; use Validsw;
-- either because the target is not byte aligned, or there is a change
-- of representation.
+ procedure Expand_Non_Function_Return (N : Node_Id);
+ -- Called by Expand_N_Simple_Return_Statement in case we're returning from
+ -- a procedure body, entry body, accept statement, or extended return
+ -- statement. Note that all non-function returns are simple return
+ -- statements.
+
+ procedure Expand_Simple_Function_Return (N : Node_Id);
+ -- Expand simple return from function. Called by
+ -- Expand_N_Simple_Return_Statement in case we're returning from a function
+ -- body.
+
function Make_Tag_Ctrl_Assignment (N : Node_Id) return List_Id;
- -- Generate the necessary code for controlled and Tagged assignment,
+ -- Generate the necessary code for controlled and tagged assignment,
-- that is to say, finalization of the target before, adjustement of
-- the target after and save and restore of the tag and finalization
-- pointers which are not 'part of the value' and must not be changed
-- upon assignment. N is the original Assignment node.
- function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean;
- -- This function is used in processing the assignment of a record or
- -- indexed component. The argument N is either the left hand or right
- -- hand side of an assignment, and this function determines if there
- -- is a record component reference where the record may be bit aligned
- -- in a manner that causes trouble for the back end (see description
- -- of Exp_Util.Component_May_Be_Bit_Aligned for further details).
-
------------------------------
-- Change_Of_Representation --
------------------------------
-- This switch is set to True if the array move must be done using
-- an explicit front end generated loop.
- procedure Apply_Dereference (Arg : in out Node_Id);
+ procedure Apply_Dereference (Arg : Node_Id);
-- If the argument is an access to an array, and the assignment is
-- converted into a procedure call, apply explicit dereference.
-- Apply_Dereference --
-----------------------
- procedure Apply_Dereference (Arg : in out Node_Id) is
+ procedure Apply_Dereference (Arg : Node_Id) is
Typ : constant Entity_Id := Etype (Arg);
begin
if Is_Access_Type (Typ) then
-- Start of processing for Expand_Assign_Array
begin
- -- Deal with length check, note that the length check is done with
+ -- Deal with length check. Note that the length check is done with
-- respect to the right hand side as given, not a possible underlying
-- renamed object, since this would generate incorrect extra checks.
Apply_Length_Check (Rhs, L_Type);
- -- We start by assuming that the move can be done in either
- -- direction, i.e. that the two sides are completely disjoint.
+ -- We start by assuming that the move can be done in either direction,
+ -- i.e. that the two sides are completely disjoint.
Set_Forwards_OK (N, True);
Set_Backwards_OK (N, True);
- -- Normally it is only the slice case that can lead to overlap,
- -- and explicit checks for slices are made below. But there is
- -- one case where the slice can be implicit and invisible to us
- -- and that is the case where we have a one dimensional array,
- -- and either both operands are parameters, or one is a parameter
- -- and the other is a global variable. In this case the parameter
- -- could be a slice that overlaps with the other parameter.
-
- -- Check for the case of slices requiring an explicit loop. Normally
- -- it is only the explicit slice cases that bother us, but in the
- -- case of one dimensional arrays, parameters can be slices that
- -- are passed by reference, so we can have aliasing for assignments
- -- from one parameter to another, or assignments between parameters
- -- and nonlocal variables. However, if the array subtype is a
- -- constrained first subtype in the parameter case, then we don't
- -- have to worry about overlap, since slice assignments aren't
- -- possible (other than for a slice denoting the whole array).
-
- -- Note: overlap is never possible if there is a change of
- -- representation, so we can exclude this case.
+ -- Normally it is only the slice case that can lead to overlap, and
+ -- explicit checks for slices are made below. But there is one case
+ -- where the slice can be implicit and invisible to us: when we have a
+ -- one dimensional array, and either both operands are parameters, or
+ -- one is a parameter (which can be a slice passed by reference) and the
+ -- other is a non-local variable. In this case the parameter could be a
+ -- slice that overlaps with the other operand.
+
+ -- However, if the array subtype is a constrained first subtype in the
+ -- parameter case, then we don't have to worry about overlap, since
+ -- slice assignments aren't possible (other than for a slice denoting
+ -- the whole array).
+
+ -- Note: No overlap is possible if there is a change of representation,
+ -- so we can exclude this case.
if Ndim = 1
and then not Crep
(not Is_Constrained (Etype (Lhs))
or else not Is_First_Subtype (Etype (Lhs)))
- -- In the case of compiling for the Java Virtual Machine,
- -- slices are always passed by making a copy, so we don't
- -- have to worry about overlap. We also want to prevent
- -- generation of "<" comparisons for array addresses,
- -- since that's a meaningless operation on the JVM.
+ -- In the case of compiling for the Java or .NET Virtual Machine,
+ -- slices are always passed by making a copy, so we don't have to
+ -- worry about overlap. We also want to prevent generation of "<"
+ -- comparisons for array addresses, since that's a meaningless
+ -- operation on the VM.
- and then not Java_VM
+ and then VM_Target = No_VM
then
Set_Forwards_OK (N, False);
Set_Backwards_OK (N, False);
- -- Note: the bit-packed case is not worrisome here, since if
- -- we have a slice passed as a parameter, it is always aligned
- -- on a byte boundary, and if there are no explicit slices, the
- -- assignment can be performed directly.
+ -- Note: the bit-packed case is not worrisome here, since if we have
+ -- a slice passed as a parameter, it is always aligned on a byte
+ -- boundary, and if there are no explicit slices, the assignment
+ -- can be performed directly.
end if;
- -- We certainly must use a loop for change of representation
- -- and also we use the operand of the conversion on the right
- -- hand side as the effective right hand side (the component
- -- types must match in this situation).
+ -- We certainly must use a loop for change of representation and also
+ -- we use the operand of the conversion on the right hand side as the
+ -- effective right hand side (the component types must match in this
+ -- situation).
if Crep then
Act_Rhs := Get_Referenced_Object (Rhs);
then
Loop_Required := True;
- -- Arrays with controlled components are expanded into a loop
- -- to force calls to adjust at the component level.
+ -- Arrays with controlled components are expanded into a loop to force
+ -- calls to Adjust at the component level.
elsif Has_Controlled_Component (L_Type) then
Loop_Required := True;
+ -- If object is atomic, we cannot tolerate a loop
+
+ elsif Is_Atomic_Object (Act_Lhs)
+ or else
+ Is_Atomic_Object (Act_Rhs)
+ then
+ return;
+
+ -- Loop is required if we have atomic components since we have to
+ -- be sure to do any accesses on an element by element basis.
+
+ elsif Has_Atomic_Components (L_Type)
+ or else Has_Atomic_Components (R_Type)
+ or else Is_Atomic (Component_Type (L_Type))
+ or else Is_Atomic (Component_Type (R_Type))
+ then
+ Loop_Required := True;
+
-- Case where no slice is involved
elsif not L_Slice and not R_Slice then
- -- The following code deals with the case of unconstrained bit
- -- packed arrays. The problem is that the template for such
- -- arrays contains the bounds of the actual source level array,
+ -- The following code deals with the case of unconstrained bit packed
+ -- arrays. The problem is that the template for such arrays contains
+ -- the bounds of the actual source level array, but the copy of an
+ -- entire array requires the bounds of the underlying array. It would
+ -- be nice if the back end could take care of this, but right now it
+ -- does not know how, so if we have such a type, then we expand out
+ -- into a loop, which is inefficient but works correctly. If we don't
+ -- do this, we get the wrong length computed for the array to be
+ -- moved. The two cases we need to worry about are:
- -- But the copy of an entire array requires the bounds of the
- -- underlying array. It would be nice if the back end could take
- -- care of this, but right now it does not know how, so if we
- -- have such a type, then we expand out into a loop, which is
- -- inefficient but works correctly. If we don't do this, we
- -- get the wrong length computed for the array to be moved.
- -- The two cases we need to worry about are:
-
- -- Explicit deference of an unconstrained packed array type as
- -- in the following example:
+ -- Explicit deference of an unconstrained packed array type as in the
+ -- following example:
-- procedure C52 is
-- type BITS is array(INTEGER range <>) of BOOLEAN;
-- P2.ALL := P1.ALL;
-- end C52;
- -- A formal parameter reference with an unconstrained bit
- -- array type is the other case we need to worry about (here
- -- we assume the same BITS type declared above:
+ -- A formal parameter reference with an unconstrained bit array type
+ -- is the other case we need to worry about (here we assume the same
+ -- BITS type declared above):
- -- procedure Write_All (File : out BITS; Contents : in BITS);
+ -- procedure Write_All (File : out BITS; Contents : BITS);
-- begin
-- File.Storage := Contents;
-- end Write_All;
Check_Unconstrained_Bit_Packed_Array : declare
function Is_UBPA_Reference (Opnd : Node_Id) return Boolean;
- -- Function to perform required test for the first case,
- -- above (dereference of an unconstrained bit packed array)
+ -- Function to perform required test for the first case, above
+ -- (dereference of an unconstrained bit packed array).
-----------------------
-- Is_UBPA_Reference --
then
Loop_Required := True;
- -- Here if we do not have the case of a reference to a bit
- -- packed unconstrained array case. In this case gigi can
- -- most certainly handle the assignment if a forwards move
- -- is allowed.
+ -- Here if we do not have the case of a reference to a bit packed
+ -- unconstrained array case. In this case gigi can most certainly
+ -- handle the assignment if a forwards move is allowed.
-- (could it handle the backwards case also???)
end if;
end Check_Unconstrained_Bit_Packed_Array;
- -- Gigi can always handle the assignment if the right side is a string
- -- literal (note that overlap is definitely impossible in this case).
- -- If the type is packed, a string literal is always converted into a
- -- aggregate, except in the case of a null slice, for which no aggregate
- -- can be written. In that case, rewrite the assignment as a null
- -- statement, a length check has already been emitted to verify that
- -- the range of the left-hand side is empty.
+ -- The back end can always handle the assignment if the right side is a
+ -- string literal (note that overlap is definitely impossible in this
+ -- case). If the type is packed, a string literal is always converted
+ -- into an aggregate, except in the case of a null slice, for which no
+ -- aggregate can be written. In that case, rewrite the assignment as a
+ -- null statement, a length check has already been emitted to verify
+ -- that the range of the left-hand side is empty.
- -- Note that this code is not executed if we had an assignment of
- -- a string literal to a non-bit aligned component of a record, a
- -- case which cannot be handled by the backend
+ -- Note that this code is not executed if we have an assignment of a
+ -- string literal to a non-bit aligned component of a record, a case
+ -- which cannot be handled by the backend.
elsif Nkind (Rhs) = N_String_Literal then
if String_Length (Strval (Rhs)) = 0
return;
- -- If either operand is bit packed, then we need a loop, since we
- -- can't be sure that the slice is byte aligned. Similarly, if either
- -- operand is a possibly unaligned slice, then we need a loop (since
- -- gigi cannot handle unaligned slices).
+ -- If either operand is bit packed, then we need a loop, since we can't
+ -- be sure that the slice is byte aligned. Similarly, if either operand
+ -- is a possibly unaligned slice, then we need a loop (since the back
+ -- end cannot handle unaligned slices).
elsif Is_Bit_Packed_Array (L_Type)
or else Is_Bit_Packed_Array (R_Type)
then
Loop_Required := True;
- -- If we are not bit-packed, and we have only one slice, then no
- -- overlap is possible except in the parameter case, so we can let
- -- gigi handle things.
+ -- If we are not bit-packed, and we have only one slice, then no overlap
+ -- is possible except in the parameter case, so we can let the back end
+ -- handle things.
elsif not (L_Slice and R_Slice) then
if Forwards_OK (N) then
end if;
end if;
- -- If the right-hand side is a string literal, introduce a temporary
- -- for it, for use in the generated loop that will follow.
+ -- If the right-hand side is a string literal, introduce a temporary for
+ -- it, for use in the generated loop that will follow.
if Nkind (Rhs) = N_String_Literal then
declare
Temp : constant Entity_Id :=
- Make_Defining_Identifier (Loc, Name_T);
+ Make_Defining_Identifier (Loc, New_Internal_Name ('T'));
Decl : Node_Id;
begin
-- Backwards_OK: Set to False if we already know that a backwards
-- move is not safe, else set to True
- -- Our task at this stage is to complete the overlap analysis, which
- -- can result in possibly setting Forwards_OK or Backwards_OK to
- -- False, and then generating the final code, either by deciding
- -- that it is OK after all to let Gigi handle it, or by generating
- -- appropriate code in the front end.
+ -- Our task at this stage is to complete the overlap analysis, which can
+ -- result in possibly setting Forwards_OK or Backwards_OK to False, and
+ -- then generating the final code, either by deciding that it is OK
+ -- after all to let Gigi handle it, or by generating appropriate code
+ -- in the front end.
declare
L_Index_Typ : constant Node_Id := Etype (First_Index (L_Type));
begin
-- Get the expressions for the arrays. If we are dealing with a
-- private type, then convert to the underlying type. We can do
- -- direct assignments to an array that is a private type, but
- -- we cannot assign to elements of the array without this extra
+ -- direct assignments to an array that is a private type, but we
+ -- cannot assign to elements of the array without this extra
-- unchecked conversion.
if Nkind (Act_Lhs) = N_Slice then
end if;
end if;
- -- If both sides are slices, we must figure out whether
- -- it is safe to do the move in one direction or the other
- -- It is always safe if there is a change of representation
- -- since obviously two arrays with different representations
- -- cannot possibly overlap.
+ -- If both sides are slices, we must figure out whether it is safe
+ -- to do the move in one direction or the other. It is always safe
+ -- if there is a change of representation since obviously two arrays
+ -- with different representations cannot possibly overlap.
if (not Crep) and L_Slice and R_Slice then
Act_L_Array := Get_Referenced_Object (Prefix (Act_Lhs));
Act_R_Array := Get_Referenced_Object (Prefix (Act_Rhs));
- -- If both left and right hand arrays are entity names, and
- -- refer to different entities, then we know that the move
- -- is safe (the two storage areas are completely disjoint).
+ -- If both left and right hand arrays are entity names, and refer
+ -- to different entities, then we know that the move is safe (the
+ -- two storage areas are completely disjoint).
if Is_Entity_Name (Act_L_Array)
and then Is_Entity_Name (Act_R_Array)
then
null;
- -- Otherwise, we assume the worst, which is that the two
- -- arrays are the same array. There is no need to check if
- -- we know that is the case, because if we don't know it,
- -- we still have to assume it!
+ -- Otherwise, we assume the worst, which is that the two arrays
+ -- are the same array. There is no need to check if we know that
+ -- is the case, because if we don't know it, we still have to
+ -- assume it!
- -- Generally if the same array is involved, then we have
- -- an overlapping case. We will have to really assume the
- -- worst (i.e. set neither of the OK flags) unless we can
- -- determine the lower or upper bounds at compile time and
- -- compare them.
+ -- Generally if the same array is involved, then we have an
+ -- overlapping case. We will have to really assume the worst (i.e.
+ -- set neither of the OK flags) unless we can determine the lower
+ -- or upper bounds at compile time and compare them.
else
Cresult := Compile_Time_Compare (Left_Lo, Right_Lo);
end if;
-- If after that analysis, Forwards_OK is still True, and
- -- Loop_Required is False, meaning that we have not discovered
- -- some non-overlap reason for requiring a loop, then we can
- -- still let gigi handle it.
+ -- Loop_Required is False, meaning that we have not discovered some
+ -- non-overlap reason for requiring a loop, then we can still let
+ -- gigi handle it.
if not Loop_Required then
if Forwards_OK (N) then
return;
-
else
null;
-- Here is where a memmove would be appropriate ???
end if;
end if;
- -- At this stage we have to generate an explicit loop, and
- -- we have the following cases:
+ -- At this stage we have to generate an explicit loop, and we have
+ -- the following cases:
-- Forwards_OK = True
-- Rnn := right_index'Succ (Rnn);
-- end loop;
- -- Note: the above code MUST be analyzed with checks off,
- -- because otherwise the Succ could overflow. But in any
- -- case this is more efficient!
+ -- Note: the above code MUST be analyzed with checks off, because
+ -- otherwise the Succ could overflow. But in any case this is more
+ -- efficient!
-- Forwards_OK = False, Backwards_OK = True
-- Rnn := right_index'Pred (Rnn);
-- end loop;
- -- Note: the above code MUST be analyzed with checks off,
- -- because otherwise the Pred could overflow. But in any
- -- case this is more efficient!
+ -- Note: the above code MUST be analyzed with checks off, because
+ -- otherwise the Pred could overflow. But in any case this is more
+ -- efficient!
-- Forwards_OK = Backwards_OK = False
-- <code for Backwards_OK = True above>
-- end if;
+ -- In order to detect possible aliasing, we examine the renamed
+ -- expression when the source or target is a renaming. However,
+ -- the renaming may be intended to capture an address that may be
+ -- affected by subsequent code, and therefore we must recover
+ -- the actual entity for the expansion that follows, not the
+ -- object it renames. In particular, if source or target designate
+ -- a portion of a dynamically allocated object, the pointer to it
+ -- may be reassigned but the renaming preserves the proper location.
+
+ if Is_Entity_Name (Rhs)
+ and then
+ Nkind (Parent (Entity (Rhs))) = N_Object_Renaming_Declaration
+ and then Nkind (Act_Rhs) = N_Slice
+ then
+ Rarray := Rhs;
+ end if;
+
+ if Is_Entity_Name (Lhs)
+ and then
+ Nkind (Parent (Entity (Lhs))) = N_Object_Renaming_Declaration
+ and then Nkind (Act_Lhs) = N_Slice
+ then
+ Larray := Lhs;
+ end if;
+
-- Cases where either Forwards_OK or Backwards_OK is true
if Forwards_OK (N) or else Backwards_OK (N) then
-- Case of both are false with implicit conditionals allowed
else
- -- Before we generate this code, we must ensure that the
- -- left and right side array types are defined. They may
- -- be itypes, and we cannot let them be defined inside the
- -- if, since the first use in the then may not be executed.
+ -- Before we generate this code, we must ensure that the left and
+ -- right side array types are defined. They may be itypes, and we
+ -- cannot let them be defined inside the if, since the first use
+ -- in the then may not be executed.
Ensure_Defined (L_Type, N);
Ensure_Defined (R_Type, N);
- -- We normally compare addresses to find out which way round
- -- to do the loop, since this is realiable, and handles the
- -- cases of parameters, conversions etc. But we can't do that
- -- in the bit packed case or the Java VM case, because addresses
- -- don't work there.
+ -- We normally compare addresses to find out which way round to
+ -- do the loop, since this is realiable, and handles the cases of
+ -- parameters, conversions etc. But we can't do that in the bit
+ -- packed case or the VM case, because addresses don't work there.
- if not Is_Bit_Packed_Array (L_Type) and then not Java_VM then
+ if not Is_Bit_Packed_Array (L_Type) and then VM_Target = No_VM then
Condition :=
Make_Op_Le (Loc,
Left_Opnd =>
Attribute_Name => Name_First))),
Attribute_Name => Name_Address)));
- -- For the bit packed and Java VM cases we use the bounds.
- -- That's OK, because we don't have to worry about parameters,
- -- since they cannot cause overlap. Perhaps we should worry
- -- about weird slice conversions ???
+ -- For the bit packed and VM cases we use the bounds. That's OK,
+ -- because we don't have to worry about parameters, since they
+ -- cannot cause overlap. Perhaps we should worry about weird slice
+ -- conversions ???
else
-- Copy the bounds and reset the Analyzed flag, because the
and then not No_Ctrl_Actions (N)
then
- -- Call TSS procedure for array assignment, passing the
- -- the explicit bounds of right- and left-hand side.
+ -- Call TSS procedure for array assignment, passing the the
+ -- explicit bounds of right and left hand sides.
declare
- Proc : constant Node_Id :=
- TSS (Base_Type (L_Type), TSS_Slice_Assign);
+ Proc : constant Node_Id :=
+ TSS (Base_Type (L_Type), TSS_Slice_Assign);
Actuals : List_Id;
begin
Duplicate_Subexpr (Left_Hi, Name_Req => True),
Duplicate_Subexpr (Right_Lo, Name_Req => True),
Duplicate_Subexpr (Right_Hi, Name_Req => True));
- Append_To (Actuals, Condition);
+
+ Append_To (Actuals,
+ Make_Op_Not (Loc,
+ Right_Opnd => Condition));
Rewrite (N,
Make_Procedure_Call_Statement (Loc,
-- Expand_Assign_Array_Loop --
------------------------------
- -- The following is an example of the loop generated for the case of
- -- a two-dimensional array:
+ -- The following is an example of the loop generated for the case of a
+ -- two-dimensional array:
-- declare
-- R2b : Tm1X1 := 1;
-- end loop;
-- end;
- -- Here Rev is False, and Tm1Xn are the subscript types for the right
- -- hand side. The declarations of R2b and R4b are inserted before the
- -- original assignment statement.
+ -- Here Rev is False, and Tm1Xn are the subscript types for the right hand
+ -- side. The declarations of R2b and R4b are inserted before the original
+ -- assignment statement.
function Expand_Assign_Array_Loop
(N : Node_Id;
Make_Assignment_Statement (Loc,
Name =>
Make_Indexed_Component (Loc,
- Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
+ Prefix => Duplicate_Subexpr (Larray, Name_Req => True),
Expressions => ExprL),
Expression =>
Make_Indexed_Component (Loc,
- Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
+ Prefix => Duplicate_Subexpr (Rarray, Name_Req => True),
Expressions => ExprR));
+ -- We set assignment OK, since there are some cases, e.g. in object
+ -- declarations, where we are actually assigning into a constant.
+ -- If there really is an illegality, it was caught long before now,
+ -- and was flagged when the original assignment was analyzed.
+
+ Set_Assignment_OK (Name (Assign));
+
-- Propagate the No_Ctrl_Actions flag to individual assignments
Set_No_Ctrl_Actions (Assign, No_Ctrl_Actions (N));
-- Expand_Assign_Record --
--------------------------
- -- The only processing required is in the change of representation
- -- case, where we must expand the assignment to a series of field
- -- by field assignments.
+ -- The only processing required is in the change of representation case,
+ -- where we must expand the assignment to a series of field by field
+ -- assignments.
procedure Expand_Assign_Record (N : Node_Id) is
Lhs : constant Node_Id := Name (N);
Rhs : Node_Id := Expression (N);
begin
- -- If change of representation, then extract the real right hand
- -- side from the type conversion, and proceed with component-wise
- -- assignment, since the two types are not the same as far as the
- -- back end is concerned.
+ -- If change of representation, then extract the real right hand side
+ -- from the type conversion, and proceed with component-wise assignment,
+ -- since the two types are not the same as far as the back end is
+ -- concerned.
if Change_Of_Representation (N) then
Rhs := Expression (Rhs);
- -- If this may be a case of a large bit aligned component, then
- -- proceed with component-wise assignment, to avoid possible
- -- clobbering of other components sharing bits in the first or
- -- last byte of the component to be assigned.
+ -- If this may be a case of a large bit aligned component, then proceed
+ -- with component-wise assignment, to avoid possible clobbering of other
+ -- components sharing bits in the first or last byte of the component to
+ -- be assigned.
elsif Possible_Bit_Aligned_Component (Lhs)
or
(Typ : Entity_Id;
Comp : Entity_Id) return Entity_Id;
-- Find the component with the given name in the underlying record
- -- declaration for Typ. We need to use the actual entity because
- -- the type may be private and resolution by identifier alone would
- -- fail.
+ -- declaration for Typ. We need to use the actual entity because the
+ -- type may be private and resolution by identifier alone would fail.
- function Make_Component_List_Assign (CL : Node_Id) return List_Id;
+ function Make_Component_List_Assign
+ (CL : Node_Id;
+ U_U : Boolean := False) return List_Id;
-- Returns a sequence of statements to assign the components that
- -- are referenced in the given component list.
-
- function Make_Field_Assign (C : Entity_Id) return Node_Id;
- -- Given C, the entity for a discriminant or component, build
- -- an assignment for the corresponding field values.
+ -- are referenced in the given component list. The flag U_U is
+ -- used to force the usage of the inferred value of the variant
+ -- part expression as the switch for the generated case statement.
+
+ function Make_Field_Assign
+ (C : Entity_Id;
+ U_U : Boolean := False) return Node_Id;
+ -- Given C, the entity for a discriminant or component, build an
+ -- assignment for the corresponding field values. The flag U_U
+ -- signals the presence of an Unchecked_Union and forces the usage
+ -- of the inferred discriminant value of C as the right hand side
+ -- of the assignment.
function Make_Field_Assigns (CI : List_Id) return List_Id;
-- Given CI, a component items list, construct series of statements
-- Make_Component_List_Assign --
--------------------------------
- function Make_Component_List_Assign (CL : Node_Id) return List_Id is
+ function Make_Component_List_Assign
+ (CL : Node_Id;
+ U_U : Boolean := False) return List_Id
+ is
CI : constant List_Id := Component_Items (CL);
VP : constant Node_Id := Variant_Part (CL);
- Result : List_Id;
Alts : List_Id;
- V : Node_Id;
DC : Node_Id;
DCH : List_Id;
+ Expr : Node_Id;
+ Result : List_Id;
+ V : Node_Id;
begin
Result := Make_Field_Assigns (CI);
Next_Non_Pragma (V);
end loop;
+ -- If we have an Unchecked_Union, use the value of the inferred
+ -- discriminant of the variant part expression as the switch
+ -- for the case statement. The case statement may later be
+ -- folded.
+
+ if U_U then
+ Expr :=
+ New_Copy (Get_Discriminant_Value (
+ Entity (Name (VP)),
+ Etype (Rhs),
+ Discriminant_Constraint (Etype (Rhs))));
+ else
+ Expr :=
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Rhs),
+ Selector_Name =>
+ Make_Identifier (Loc, Chars (Name (VP))));
+ end if;
+
Append_To (Result,
Make_Case_Statement (Loc,
- Expression =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (Rhs),
- Selector_Name =>
- Make_Identifier (Loc, Chars (Name (VP)))),
+ Expression => Expr,
Alternatives => Alts));
-
end if;
return Result;
-- Make_Field_Assign --
-----------------------
- function Make_Field_Assign (C : Entity_Id) return Node_Id is
- A : Node_Id;
+ function Make_Field_Assign
+ (C : Entity_Id;
+ U_U : Boolean := False) return Node_Id
+ is
+ A : Node_Id;
+ Expr : Node_Id;
begin
+ -- In the case of an Unchecked_Union, use the discriminant
+ -- constraint value as on the right hand side of the assignment.
+
+ if U_U then
+ Expr :=
+ New_Copy (Get_Discriminant_Value (C,
+ Etype (Rhs),
+ Discriminant_Constraint (Etype (Rhs))));
+ else
+ Expr :=
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Rhs),
+ Selector_Name => New_Occurrence_Of (C, Loc));
+ end if;
+
A :=
Make_Assignment_Statement (Loc,
Name =>
Prefix => Duplicate_Subexpr (Lhs),
Selector_Name =>
New_Occurrence_Of (Find_Component (L_Typ, C), Loc)),
- Expression =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (Rhs),
- Selector_Name => New_Occurrence_Of (C, Loc)));
+ Expression => Expr);
-- Set Assignment_OK, so discriminants can be assigned
begin
Item := First (CI);
Result := New_List;
-
while Present (Item) loop
if Nkind (Item) = N_Component_Declaration then
Append_To
if Has_Discriminants (L_Typ) then
F := First_Discriminant (R_Typ);
while Present (F) loop
- Insert_Action (N, Make_Field_Assign (F));
+
+ if Is_Unchecked_Union (Base_Type (R_Typ)) then
+ Insert_Action (N, Make_Field_Assign (F, True));
+ else
+ Insert_Action (N, Make_Field_Assign (F));
+ end if;
+
Next_Discriminant (F);
end loop;
end if;
if Nkind (RDef) = N_Record_Definition
and then Present (Component_List (RDef))
then
- Insert_Actions
- (N, Make_Component_List_Assign (Component_List (RDef)));
+
+ if Is_Unchecked_Union (R_Typ) then
+ Insert_Actions (N,
+ Make_Component_List_Assign (Component_List (RDef), True));
+ else
+ Insert_Actions
+ (N, Make_Component_List_Assign (Component_List (RDef)));
+ end if;
Rewrite (N, Make_Null_Statement (Loc));
end if;
-- Expand_N_Assignment_Statement --
-----------------------------------
- -- For array types, deal with slice assignments and setting the flags
- -- to indicate if it can be statically determined which direction the
- -- move should go in. Also deal with generating range/length checks.
+ -- This procedure implements various cases where an assignment statement
+ -- cannot just be passed on to the back end in untransformed state.
procedure Expand_N_Assignment_Statement (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Exp : Node_Id;
begin
- -- First deal with generation of range check if required. For now
- -- we do this only for discrete types.
+ -- Ada 2005 (AI-327): Handle assignment to priority of protected object
+
+ -- Rewrite an assignment to X'Priority into a run-time call
+
+ -- For example: X'Priority := New_Prio_Expr;
+ -- ...is expanded into Set_Ceiling (X._Object, New_Prio_Expr);
+
+ -- Note that although X'Priority is notionally an object, it is quite
+ -- deliberately not defined as an aliased object in the RM. This means
+ -- that it works fine to rewrite it as a call, without having to worry
+ -- about complications that would other arise from X'Priority'Access,
+ -- which is illegal, because of the lack of aliasing.
+
+ if Ada_Version >= Ada_05 then
+ declare
+ Call : Node_Id;
+ Conctyp : Entity_Id;
+ Ent : Entity_Id;
+ Subprg : Entity_Id;
+ RT_Subprg_Name : Node_Id;
+
+ begin
+ -- Handle chains of renamings
+
+ Ent := Name (N);
+ while Nkind (Ent) in N_Has_Entity
+ and then Present (Entity (Ent))
+ and then Present (Renamed_Object (Entity (Ent)))
+ loop
+ Ent := Renamed_Object (Entity (Ent));
+ end loop;
+
+ -- The attribute Priority applied to protected objects has been
+ -- previously expanded into a call to the Get_Ceiling run-time
+ -- subprogram.
+
+ if Nkind (Ent) = N_Function_Call
+ and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
+ or else
+ Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling))
+ then
+ -- Look for the enclosing concurrent type
+
+ Conctyp := Current_Scope;
+ while not Is_Concurrent_Type (Conctyp) loop
+ Conctyp := Scope (Conctyp);
+ end loop;
+
+ pragma Assert (Is_Protected_Type (Conctyp));
+
+ -- Generate the first actual of the call
+
+ Subprg := Current_Scope;
+ while not Present (Protected_Body_Subprogram (Subprg)) loop
+ Subprg := Scope (Subprg);
+ end loop;
+
+ -- Select the appropriate run-time call
+
+ if Number_Entries (Conctyp) = 0 then
+ RT_Subprg_Name :=
+ New_Reference_To (RTE (RE_Set_Ceiling), Loc);
+ else
+ RT_Subprg_Name :=
+ New_Reference_To (RTE (RO_PE_Set_Ceiling), Loc);
+ end if;
+
+ Call :=
+ Make_Procedure_Call_Statement (Loc,
+ Name => RT_Subprg_Name,
+ Parameter_Associations => New_List (
+ New_Copy_Tree (First (Parameter_Associations (Ent))),
+ Relocate_Node (Expression (N))));
+
+ Rewrite (N, Call);
+ Analyze (N);
+ return;
+ end if;
+ end;
+ end if;
+
+ -- First deal with generation of range check if required. For now we do
+ -- this only for discrete types.
if Do_Range_Check (Rhs)
and then Is_Discrete_Type (Typ)
-- packed array is as follows:
-- An indexed component whose prefix is a bit packed array is a
- -- reference to a bit packed array.
+ -- reference to a bit packed array.
-- An indexed component or selected component whose prefix is a
- -- reference to a bit packed array is itself a reference ot a
- -- bit packed array.
+ -- reference to a bit packed array is itself a reference ot a
+ -- bit packed array.
-- The required transformation is
Chars => New_Internal_Name ('T'));
begin
- -- Insert the post assignment first, because we want to copy
- -- the BPAR_Expr tree before it gets analyzed in the context
- -- of the pre assignment. Note that we do not analyze the
- -- post assignment yet (we cannot till we have completed the
- -- analysis of the pre assignment). As usual, the analysis
- -- of this post assignment will happen on its own when we
- -- "run into" it after finishing the current assignment.
+ -- Insert the post assignment first, because we want to copy the
+ -- BPAR_Expr tree before it gets analyzed in the context of the
+ -- pre assignment. Note that we do not analyze the post assignment
+ -- yet (we cannot till we have completed the analysis of the pre
+ -- assignment). As usual, the analysis of this post assignment
+ -- will happen on its own when we "run into" it after finishing
+ -- the current assignment.
Insert_After (N,
Make_Assignment_Statement (Loc,
Name => New_Copy_Tree (BPAR_Expr),
Expression => New_Occurrence_Of (Tnn, Loc)));
- -- At this stage BPAR_Expr is a reference to a bit packed
- -- array where the reference was not expanded in the original
- -- tree, since it was on the left side of an assignment. But
- -- in the pre-assignment statement (the object definition),
- -- BPAR_Expr will end up on the right hand side, and must be
- -- reexpanded. To achieve this, we reset the analyzed flag
- -- of all selected and indexed components down to the actual
- -- indexed component for the packed array.
+ -- At this stage BPAR_Expr is a reference to a bit packed array
+ -- where the reference was not expanded in the original tree,
+ -- since it was on the left side of an assignment. But in the
+ -- pre-assignment statement (the object definition), BPAR_Expr
+ -- will end up on the right hand side, and must be reexpanded. To
+ -- achieve this, we reset the analyzed flag of all selected and
+ -- indexed components down to the actual indexed component for
+ -- the packed array.
Exp := BPAR_Expr;
loop
end if;
end loop;
- -- Now we can insert and analyze the pre-assignment.
+ -- Now we can insert and analyze the pre-assignment
-- If the right-hand side requires a transient scope, it has
-- already been placed on the stack. However, the declaration is
declare
Uses_Transient_Scope : constant Boolean :=
- Scope_Is_Transient and then N = Node_To_Be_Wrapped;
+ Scope_Is_Transient
+ and then N = Node_To_Be_Wrapped;
begin
if Uses_Transient_Scope then
- New_Scope (Scope (Current_Scope));
+ Push_Scope (Scope (Current_Scope));
end if;
Insert_Before_And_Analyze (N,
-- We do not need to reanalyze that assignment, and we do not need
-- to worry about references to the temporary, but we do need to
-- make sure that the temporary is not marked as a true constant
- -- since we now have a generate assignment to it!
+ -- since we now have a generated assignment to it!
Set_Is_True_Constant (Tnn, False);
end;
end if;
- -- When we have the appropriate type of aggregate in the
- -- expression (it has been determined during analysis of the
- -- aggregate by setting the delay flag), let's perform in place
- -- assignment and thus avoid creating a temporay.
+ -- When we have the appropriate type of aggregate in the expression (it
+ -- has been determined during analysis of the aggregate by setting the
+ -- delay flag), let's perform in place assignment and thus avoid
+ -- creating a temporary.
if Is_Delayed_Aggregate (Rhs) then
Convert_Aggr_In_Assignment (N);
return;
end if;
- -- Apply discriminant check if required. If Lhs is an access type
- -- to a designated type with discriminants, we must always check.
+ -- Apply discriminant check if required. If Lhs is an access type to a
+ -- designated type with discriminants, we must always check.
if Has_Discriminants (Etype (Lhs)) then
-- create dereferences but are not semantic aliasings.
elsif Is_Private_Type (Etype (Lhs))
- and then Has_Discriminants (Typ)
+ and then Has_Discriminants (Typ)
and then Nkind (Lhs) = N_Explicit_Dereference
and then Comes_From_Source (Lhs)
then
Rewrite (Rhs, OK_Convert_To (Base_Type (Typ), Rhs));
Apply_Discriminant_Check (Rhs, Typ, Lhs);
- -- In the access type case, we need the same discriminant check,
- -- and also range checks if we have an access to constrained array.
+ -- In the access type case, we need the same discriminant check, and
+ -- also range checks if we have an access to constrained array.
elsif Is_Access_Type (Etype (Lhs))
and then Is_Constrained (Designated_Type (Etype (Lhs)))
begin
C_Es :=
- Range_Check
+ Get_Range_Checks
(Lhs,
Target_Typ,
Etype (Designated_Type (Etype (Lhs))));
(Expression (Rhs), Designated_Type (Etype (Lhs)));
end if;
- -- Ada 2005 (AI-231): Generate conversion to the null-excluding
- -- type to force the corresponding run-time check
-
- if Is_Access_Type (Typ)
- and then
- ((Is_Entity_Name (Lhs) and then Can_Never_Be_Null (Entity (Lhs)))
- or else Can_Never_Be_Null (Etype (Lhs)))
- then
- Rewrite (Rhs, Convert_To (Etype (Lhs),
- Relocate_Node (Rhs)));
- Analyze_And_Resolve (Rhs, Etype (Lhs));
- end if;
-
- -- If we are assigning an access type and the left side is an
- -- entity, then make sure that Is_Known_Non_Null properly
- -- reflects the state of the entity after the assignment
+ -- Ada 2005 (AI-231): Generate the run-time check
if Is_Access_Type (Typ)
- and then Is_Entity_Name (Lhs)
- and then Known_Non_Null (Rhs)
- and then Safe_To_Capture_Value (N, Entity (Lhs))
+ and then Can_Never_Be_Null (Etype (Lhs))
+ and then not Can_Never_Be_Null (Etype (Rhs))
then
- Set_Is_Known_Non_Null (Entity (Lhs), Known_Non_Null (Rhs));
+ Apply_Constraint_Check (Rhs, Etype (Lhs));
end if;
-- Case of assignment to a bit packed array element
Expand_Bit_Packed_Element_Set (N);
return;
- -- Case of tagged type assignment
+ -- Build-in-place function call case. Note that we're not yet doing
+ -- build-in-place for user-written assignment statements (the assignment
+ -- here came from an aggregate.)
+
+ elsif Ada_Version >= Ada_05
+ and then Is_Build_In_Place_Function_Call (Rhs)
+ then
+ Make_Build_In_Place_Call_In_Assignment (N, Rhs);
+
+ elsif Is_Tagged_Type (Typ) and then Is_Value_Type (Etype (Lhs)) then
+
+ -- Nothing to do for valuetypes
+ -- ??? Set_Scope_Is_Transient (False);
+
+ return;
elsif Is_Tagged_Type (Typ)
or else (Controlled_Type (Typ) and then not Is_Array_Type (Typ))
begin
-- In the controlled case, we need to make sure that function
- -- calls are evaluated before finalizing the target. In all
- -- cases, it makes the expansion easier if the side-effects
- -- are removed first.
+ -- calls are evaluated before finalizing the target. In all cases,
+ -- it makes the expansion easier if the side-effects are removed
+ -- first.
Remove_Side_Effects (Lhs);
Remove_Side_Effects (Rhs);
if Is_Class_Wide_Type (Typ)
- -- If the type is tagged, we may as well use the predefined
- -- primitive assignment. This avoids inlining a lot of code
- -- and in the class-wide case, the assignment is replaced by
- -- a dispatch call to _assign. Note that this cannot be done
- -- when discriminant checks are locally suppressed (as in
- -- extension aggregate expansions) because otherwise the
- -- discriminant check will be performed within the _assign
- -- call.
-
- or else (Is_Tagged_Type (Typ)
- and then Chars (Current_Scope) /= Name_uAssign
- and then Expand_Ctrl_Actions
- and then not Discriminant_Checks_Suppressed (Empty))
+ -- If the type is tagged, we may as well use the predefined
+ -- primitive assignment. This avoids inlining a lot of code
+ -- and in the class-wide case, the assignment is replaced by
+ -- dispatch call to _assign. Note that this cannot be done when
+ -- discriminant checks are locally suppressed (as in extension
+ -- aggregate expansions) because otherwise the discriminant
+ -- check will be performed within the _assign call. It is also
+ -- suppressed for assignmments created by the expander that
+ -- correspond to initializations, where we do want to copy the
+ -- tag (No_Ctrl_Actions flag set True). by the expander and we
+ -- do not need to mess with tags ever (Expand_Ctrl_Actions flag
+ -- is set True in this case).
+
+ or else (Is_Tagged_Type (Typ)
+ and then not Is_Value_Type (Etype (Lhs))
+ and then Chars (Current_Scope) /= Name_uAssign
+ and then Expand_Ctrl_Actions
+ and then not Discriminant_Checks_Suppressed (Empty))
then
- -- Fetch the primitive op _assign and proper type to call
- -- it. Because of possible conflits between private and
- -- full view the proper type is fetched directly from the
- -- operation profile.
+ -- Fetch the primitive op _assign and proper type to call it.
+ -- Because of possible conflits between private and full view
+ -- the proper type is fetched directly from the operation
+ -- profile.
declare
Op : constant Entity_Id :=
begin
-- If the assignment is dispatching, make sure to use the
- -- ??? where is rest of this comment ???
+ -- proper type.
if Is_Class_Wide_Type (Typ) then
F_Typ := Class_Wide_Type (F_Typ);
end if;
- L := New_List (
+ L := New_List;
+
+ -- In case of assignment to a class-wide tagged type, before
+ -- the assignment we generate run-time check to ensure that
+ -- the tags of source and target match.
+
+ if Is_Class_Wide_Type (Typ)
+ and then Is_Tagged_Type (Typ)
+ and then Is_Tagged_Type (Underlying_Type (Etype (Rhs)))
+ then
+ Append_To (L,
+ Make_Raise_Constraint_Error (Loc,
+ Condition =>
+ Make_Op_Ne (Loc,
+ Left_Opnd =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Lhs),
+ Selector_Name =>
+ Make_Identifier (Loc,
+ Chars => Name_uTag)),
+ Right_Opnd =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Rhs),
+ Selector_Name =>
+ Make_Identifier (Loc,
+ Chars => Name_uTag))),
+ Reason => CE_Tag_Check_Failed));
+ end if;
+
+ Append_To (L,
Make_Procedure_Call_Statement (Loc,
Name => New_Reference_To (Op, Loc),
Parameter_Associations => New_List (
- Unchecked_Convert_To (F_Typ, Duplicate_Subexpr (Lhs)),
+ Unchecked_Convert_To (F_Typ,
+ Duplicate_Subexpr (Lhs)),
Unchecked_Convert_To (F_Typ,
Duplicate_Subexpr (Rhs)))));
end;
else
L := Make_Tag_Ctrl_Assignment (N);
- -- We can't afford to have destructive Finalization Actions
- -- in the Self assignment case, so if the target and the
- -- source are not obviously different, code is generated to
- -- avoid the self assignment case
- --
+ -- We can't afford to have destructive Finalization Actions in
+ -- the Self assignment case, so if the target and the source
+ -- are not obviously different, code is generated to avoid the
+ -- self assignment case:
+
-- if lhs'address /= rhs'address then
-- <code for controlled and/or tagged assignment>
-- end if;
end if;
-- We need to set up an exception handler for implementing
- -- 7.6.1 (18). The remaining adjustments are tackled by the
+ -- 7.6.1(18). The remaining adjustments are tackled by the
-- implementation of adjust for record_controllers (see
- -- s-finimp.adb)
+ -- s-finimp.adb).
-- This is skipped if we have no finalization
Make_Handled_Sequence_Of_Statements (Loc,
Statements => L,
Exception_Handlers => New_List (
- Make_Exception_Handler (Loc,
- Exception_Choices =>
- New_List (Make_Others_Choice (Loc)),
- Statements => New_List (
- Make_Raise_Program_Error (Loc,
- Reason =>
- PE_Finalize_Raised_Exception)
- ))))));
+ Make_Handler_For_Ctrl_Operation (Loc)))));
end if;
end if;
Make_Handled_Sequence_Of_Statements (Loc, Statements => L)));
-- If no restrictions on aborts, protect the whole assignement
- -- for controlled objects as per 9.8(11)
+ -- for controlled objects as per 9.8(11).
if Controlled_Type (Typ)
and then Expand_Ctrl_Actions
then
declare
Blk : constant Entity_Id :=
- New_Internal_Entity (
- E_Block, Current_Scope, Sloc (N), 'B');
+ New_Internal_Entity
+ (E_Block, Current_Scope, Sloc (N), 'B');
begin
Set_Scope (Blk, Current_Scope);
end;
end if;
- Analyze (N);
+ -- N has been rewritten to a block statement for which it is
+ -- known by construction that no checks are necessary: analyze
+ -- it with all checks suppressed.
+
+ Analyze (N, Suppress => All_Checks);
return;
end Tagged_Case;
Expand_Assign_Record (N);
return;
- -- Scalar types. This is where we perform the processing related
- -- to the requirements of (RM 13.9.1(9-11)) concerning the handling
- -- of invalid scalar values.
+ -- Scalar types. This is where we perform the processing related to the
+ -- requirements of (RM 13.9.1(9-11)) concerning the handling of invalid
+ -- scalar values.
elsif Is_Scalar_Type (Typ) then
if Expr_Known_Valid (Rhs) then
- -- Here the right side is valid, so it is fine. The case to
- -- deal with is when the left side is a local variable reference
- -- whose value is not currently known to be valid. If this is
- -- the case, and the assignment appears in an unconditional
- -- context, then we can mark the left side as now being valid.
+ -- Here the right side is valid, so it is fine. The case to deal
+ -- with is when the left side is a local variable reference whose
+ -- value is not currently known to be valid. If this is the case,
+ -- and the assignment appears in an unconditional context, then we
+ -- can mark the left side as now being valid.
if Is_Local_Variable_Reference (Lhs)
and then not Is_Known_Valid (Entity (Lhs))
end if;
-- Case where right side may be invalid in the sense of the RM
- -- reference above. The RM does not require that we check for
- -- the validity on an assignment, but it does require that the
- -- assignment of an invalid value not cause erroneous behavior.
+ -- reference above. The RM does not require that we check for the
+ -- validity on an assignment, but it does require that the assignment
+ -- of an invalid value not cause erroneous behavior.
-- The general approach in GNAT is to use the Is_Known_Valid flag
-- to avoid the need for validity checking on assignments. However
-- Validate right side if we are validating copies
if Validity_Checks_On
- and then Validity_Check_Copies
+ and then Validity_Check_Copies
then
- Ensure_Valid (Rhs);
+ -- Skip this if left hand side is an array or record component
+ -- and elementary component validity checks are suppressed.
+
+ if (Nkind (Lhs) = N_Selected_Component
+ or else
+ Nkind (Lhs) = N_Indexed_Component)
+ and then not Validity_Check_Components
+ then
+ null;
+ else
+ Ensure_Valid (Rhs);
+ end if;
-- We can propagate this to the left side where appropriate
-- Otherwise check to see what should be done
- -- If left side is a local variable, then we just set its
- -- flag to indicate that its value may no longer be valid,
- -- since we are copying a potentially invalid value.
+ -- If left side is a local variable, then we just set its flag to
+ -- indicate that its value may no longer be valid, since we are
+ -- copying a potentially invalid value.
elsif Is_Local_Variable_Reference (Lhs) then
Set_Is_Known_Valid (Entity (Lhs), False);
- -- Check for case of a nonlocal variable on the left side
- -- which is currently known to be valid. In this case, we
- -- simply ensure that the right side is valid. We only play
- -- the game of copying validity status for local variables,
- -- since we are doing this statically, not by tracing the
- -- full flow graph.
+ -- Check for case of a nonlocal variable on the left side which
+ -- is currently known to be valid. In this case, we simply ensure
+ -- that the right side is valid. We only play the game of copying
+ -- validity status for local variables, since we are doing this
+ -- statically, not by tracing the full flow graph.
elsif Is_Entity_Name (Lhs)
and then Is_Known_Valid (Entity (Lhs))
then
- -- Note that the Ensure_Valid call is ignored if the
- -- Validity_Checking mode is set to none so we do not
- -- need to worry about that case here.
+ -- Note: If Validity_Checking mode is set to none, we ignore
+ -- the Ensure_Valid call so don't worry about that case here.
Ensure_Valid (Rhs);
- -- In all other cases, we can safely copy an invalid value
- -- without worrying about the status of the left side. Since
- -- it is not a variable reference it will not be considered
+ -- In all other cases, we can safely copy an invalid value without
+ -- worrying about the status of the left side. Since it is not a
+ -- variable reference it will not be considered
-- as being known to be valid in any case.
else
end if;
end if;
- -- Defend against invalid subscripts on left side if we are in
- -- standard validity checking mode. No need to do this if we
- -- are checking all subscripts.
+ -- Defend against invalid subscripts on left side if we are in standard
+ -- validity checking mode. No need to do this if we are checking all
+ -- subscripts.
if Validity_Checks_On
and then Validity_Check_Default
Chlist : List_Id;
begin
- -- Check for the situation where we know at compile time which
- -- branch will be taken
+ -- Check for the situation where we know at compile time which branch
+ -- will be taken
if Compile_Time_Known_Value (Expr) then
Alt := Find_Static_Alternative (N);
- -- Move the statements from this alternative after the case
- -- statement. They are already analyzed, so will be skipped
- -- by the analyzer.
+ -- Move statements from this alternative after the case statement.
+ -- They are already analyzed, so will be skipped by the analyzer.
Insert_List_After (N, Statements (Alt));
- -- That leaves the case statement as a shell. The alternative
- -- that will be executed is reset to a null list. So now we can
- -- kill the entire case statement.
+ -- That leaves the case statement as a shell. So now we can kill all
+ -- other alternatives in the case statement.
Kill_Dead_Code (Expression (N));
- Kill_Dead_Code (Alternatives (N));
+
+ declare
+ A : Node_Id;
+
+ begin
+ -- Loop through case alternatives, skipping pragmas, and skipping
+ -- the one alternative that we select (and therefore retain).
+
+ A := First (Alternatives (N));
+ while Present (A) loop
+ if A /= Alt
+ and then Nkind (A) = N_Case_Statement_Alternative
+ then
+ Kill_Dead_Code (Statements (A), Warn_On_Deleted_Code);
+ end if;
+
+ Next (A);
+ end loop;
+ end;
+
Rewrite (N, Make_Null_Statement (Loc));
return;
end if;
Ensure_Valid (Expr);
end if;
- -- If there is only a single alternative, just replace it with
- -- the sequence of statements since obviously that is what is
- -- going to be executed in all cases.
+ -- If there is only a single alternative, just replace it with the
+ -- sequence of statements since obviously that is what is going to
+ -- be executed in all cases.
Len := List_Length (Alternatives (N));
Insert_List_After (N, Statements (First (Alternatives (N))));
- -- That leaves the case statement as a shell. The alternative
- -- that will be executed is reset to a null list. So now we can
- -- kill the entire case statement.
+ -- That leaves the case statement as a shell. The alternative that
+ -- will be executed is reset to a null list. So now we can kill
+ -- the entire case statement.
Kill_Dead_Code (Expression (N));
Rewrite (N, Make_Null_Statement (Loc));
end if;
end if;
- -- If the last alternative is not an Others choice, replace it
- -- with an N_Others_Choice. Note that we do not bother to call
- -- Analyze on the modified case statement, since it's only effect
- -- would be to compute the contents of the Others_Discrete_Choices
- -- which is not needed by the back end anyway.
+ -- If the last alternative is not an Others choice, replace it with
+ -- an N_Others_Choice. Note that we do not bother to call Analyze on
+ -- the modified case statement, since it's only effect would be to
+ -- compute the contents of the Others_Discrete_Choices which is not
+ -- needed by the back end anyway.
-- The reason we do this is that the back end always needs some
-- default for a switch, so if we have not supplied one in the
- -- processing above for validity checking, then we need to
- -- supply one here.
+ -- processing above for validity checking, then we need to supply
+ -- one here.
if not Others_Present then
Others_Node := Make_Others_Choice (Sloc (Last_Alt));
Adjust_Condition (Condition (N));
end Expand_N_Exit_Statement;
+ ----------------------------------------
+ -- Expand_N_Extended_Return_Statement --
+ ----------------------------------------
+
+ -- If there is a Handled_Statement_Sequence, we rewrite this:
+
+ -- return Result : T := <expression> do
+ -- <handled_seq_of_stms>
+ -- end return;
+
+ -- to be:
+
+ -- declare
+ -- Result : T := <expression>;
+ -- begin
+ -- <handled_seq_of_stms>
+ -- return Result;
+ -- end;
+
+ -- Otherwise (no Handled_Statement_Sequence), we rewrite this:
+
+ -- return Result : T := <expression>;
+
+ -- to be:
+
+ -- return <expression>;
+
+ -- unless it's build-in-place or there's no <expression>, in which case
+ -- we generate:
+
+ -- declare
+ -- Result : T := <expression>;
+ -- begin
+ -- return Result;
+ -- end;
+
+ -- Note that this case could have been written by the user as an extended
+ -- return statement, or could have been transformed to this from a simple
+ -- return statement.
+
+ -- That is, we need to have a reified return object if there are statements
+ -- (which might refer to it) or if we're doing build-in-place (so we can
+ -- set its address to the final resting place or if there is no expression
+ -- (in which case default initial values might need to be set).
+
+ procedure Expand_N_Extended_Return_Statement (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+
+ Return_Object_Entity : constant Entity_Id :=
+ First_Entity (Return_Statement_Entity (N));
+ Return_Object_Decl : constant Node_Id :=
+ Parent (Return_Object_Entity);
+ Parent_Function : constant Entity_Id :=
+ Return_Applies_To (Return_Statement_Entity (N));
+ Is_Build_In_Place : constant Boolean :=
+ Is_Build_In_Place_Function (Parent_Function);
+
+ Return_Stm : Node_Id;
+ Statements : List_Id;
+ Handled_Stm_Seq : Node_Id;
+ Result : Node_Id;
+ Exp : Node_Id;
+
+ function Move_Activation_Chain return Node_Id;
+ -- Construct a call to System.Tasking.Stages.Move_Activation_Chain
+ -- with parameters:
+ -- From current activation chain
+ -- To activation chain passed in by the caller
+ -- New_Master master passed in by the caller
+
+ function Move_Final_List return Node_Id;
+ -- Construct call to System.Finalization_Implementation.Move_Final_List
+ -- with parameters:
+ --
+ -- From finalization list of the return statement
+ -- To finalization list passed in by the caller
+
+ ---------------------------
+ -- Move_Activation_Chain --
+ ---------------------------
+
+ function Move_Activation_Chain return Node_Id is
+ Activation_Chain_Formal : constant Entity_Id :=
+ Build_In_Place_Formal
+ (Parent_Function, BIP_Activation_Chain);
+ To : constant Node_Id :=
+ New_Reference_To
+ (Activation_Chain_Formal, Loc);
+ Master_Formal : constant Entity_Id :=
+ Build_In_Place_Formal
+ (Parent_Function, BIP_Master);
+ New_Master : constant Node_Id :=
+ New_Reference_To (Master_Formal, Loc);
+
+ Chain_Entity : Entity_Id;
+ From : Node_Id;
+
+ begin
+ Chain_Entity := First_Entity (Return_Statement_Entity (N));
+ while Chars (Chain_Entity) /= Name_uChain loop
+ Chain_Entity := Next_Entity (Chain_Entity);
+ end loop;
+
+ From :=
+ Make_Attribute_Reference (Loc,
+ Prefix => New_Reference_To (Chain_Entity, Loc),
+ Attribute_Name => Name_Unrestricted_Access);
+ -- ??? Not clear why "Make_Identifier (Loc, Name_uChain)" doesn't
+ -- work, instead of "New_Reference_To (Chain_Entity, Loc)" above.
+
+ return
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To (RTE (RE_Move_Activation_Chain), Loc),
+ Parameter_Associations => New_List (From, To, New_Master));
+ end Move_Activation_Chain;
+
+ ---------------------
+ -- Move_Final_List --
+ ---------------------
+
+ function Move_Final_List return Node_Id is
+ Flist : constant Entity_Id :=
+ Finalization_Chain_Entity (Return_Statement_Entity (N));
+
+ From : constant Node_Id := New_Reference_To (Flist, Loc);
+
+ Caller_Final_List : constant Entity_Id :=
+ Build_In_Place_Formal
+ (Parent_Function, BIP_Final_List);
+
+ To : constant Node_Id := New_Reference_To (Caller_Final_List, Loc);
+
+ begin
+ -- Catch cases where a finalization chain entity has not been
+ -- associated with the return statement entity.
+
+ pragma Assert (Present (Flist));
+
+ -- Build required call
+
+ return
+ Make_If_Statement (Loc,
+ Condition =>
+ Make_Op_Ne (Loc,
+ Left_Opnd => New_Copy (From),
+ Right_Opnd => New_Node (N_Null, Loc)),
+ Then_Statements =>
+ New_List (
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To (RTE (RE_Move_Final_List), Loc),
+ Parameter_Associations => New_List (From, To))));
+ end Move_Final_List;
+
+ -- Start of processing for Expand_N_Extended_Return_Statement
+
+ begin
+ if Nkind (Return_Object_Decl) = N_Object_Declaration then
+ Exp := Expression (Return_Object_Decl);
+ else
+ Exp := Empty;
+ end if;
+
+ Handled_Stm_Seq := Handled_Statement_Sequence (N);
+
+ -- Build a simple_return_statement that returns the return object when
+ -- there is a statement sequence, or no expression, or the result will
+ -- be built in place. Note however that we currently do this for all
+ -- composite cases, even though nonlimited composite results are not yet
+ -- built in place (though we plan to do so eventually).
+
+ if Present (Handled_Stm_Seq)
+ or else Is_Composite_Type (Etype (Parent_Function))
+ or else No (Exp)
+ then
+ if No (Handled_Stm_Seq) then
+ Statements := New_List;
+
+ -- If the extended return has a handled statement sequence, then wrap
+ -- it in a block and use the block as the first statement.
+
+ else
+ Statements :=
+ New_List (Make_Block_Statement (Loc,
+ Declarations => New_List,
+ Handled_Statement_Sequence => Handled_Stm_Seq));
+ end if;
+
+ -- If control gets past the above Statements, we have successfully
+ -- completed the return statement. If the result type has controlled
+ -- parts and the return is for a build-in-place function, then we
+ -- call Move_Final_List to transfer responsibility for finalization
+ -- of the return object to the caller. An alternative would be to
+ -- declare a Success flag in the function, initialize it to False,
+ -- and set it to True here. Then move the Move_Final_List call into
+ -- the cleanup code, and check Success. If Success then make a call
+ -- to Move_Final_List else do finalization. Then we can remove the
+ -- abort-deferral and the nulling-out of the From parameter from
+ -- Move_Final_List. Note that the current method is not quite correct
+ -- in the rather obscure case of a select-then-abort statement whose
+ -- abortable part contains the return statement.
+
+ -- We test the type of the expression as well as the return type
+ -- of the function, because the latter may be a class-wide type
+ -- which is always treated as controlled, while the expression itself
+ -- has to have a definite type. The expression may be absent if a
+ -- constrained aggregate has been expanded into component assignments
+ -- so we have to check for this as well.
+
+ if Is_Build_In_Place
+ and then Controlled_Type (Etype (Parent_Function))
+ then
+ if not Is_Class_Wide_Type (Etype (Parent_Function))
+ or else
+ (Present (Exp)
+ and then Controlled_Type (Etype (Exp)))
+ then
+ Append_To (Statements, Move_Final_List);
+ end if;
+ end if;
+
+ -- Similarly to the above Move_Final_List, if the result type
+ -- contains tasks, we call Move_Activation_Chain. Later, the cleanup
+ -- code will call Complete_Master, which will terminate any
+ -- unactivated tasks belonging to the return statement master. But
+ -- Move_Activation_Chain updates their master to be that of the
+ -- caller, so they will not be terminated unless the return statement
+ -- completes unsuccessfully due to exception, abort, goto, or exit.
+ -- As a formality, we test whether the function requires the result
+ -- to be built in place, though that's necessarily true for the case
+ -- of result types with task parts.
+
+ if Is_Build_In_Place and Has_Task (Etype (Parent_Function)) then
+ Append_To (Statements, Move_Activation_Chain);
+ end if;
+
+ -- Build a simple_return_statement that returns the return object
+
+ Return_Stm :=
+ Make_Simple_Return_Statement (Loc,
+ Expression => New_Occurrence_Of (Return_Object_Entity, Loc));
+ Append_To (Statements, Return_Stm);
+
+ Handled_Stm_Seq :=
+ Make_Handled_Sequence_Of_Statements (Loc, Statements);
+ end if;
+
+ -- Case where we build a block
+
+ if Present (Handled_Stm_Seq) then
+ Result :=
+ Make_Block_Statement (Loc,
+ Declarations => Return_Object_Declarations (N),
+ Handled_Statement_Sequence => Handled_Stm_Seq);
+
+ -- We set the entity of the new block statement to be that of the
+ -- return statement. This is necessary so that various fields, such
+ -- as Finalization_Chain_Entity carry over from the return statement
+ -- to the block. Note that this block is unusual, in that its entity
+ -- is an E_Return_Statement rather than an E_Block.
+
+ Set_Identifier
+ (Result, New_Occurrence_Of (Return_Statement_Entity (N), Loc));
+
+ -- If the object decl was already rewritten as a renaming, then
+ -- we don't want to do the object allocation and transformation of
+ -- of the return object declaration to a renaming. This case occurs
+ -- when the return object is initialized by a call to another
+ -- build-in-place function, and that function is responsible for the
+ -- allocation of the return object.
+
+ if Is_Build_In_Place
+ and then
+ Nkind (Return_Object_Decl) = N_Object_Renaming_Declaration
+ then
+ Set_By_Ref (Return_Stm); -- Return build-in-place results by ref
+
+ elsif Is_Build_In_Place then
+
+ -- Locate the implicit access parameter associated with the
+ -- caller-supplied return object and convert the return
+ -- statement's return object declaration to a renaming of a
+ -- dereference of the access parameter. If the return object's
+ -- declaration includes an expression that has not already been
+ -- expanded as separate assignments, then add an assignment
+ -- statement to ensure the return object gets initialized.
+
+ -- declare
+ -- Result : T [:= <expression>];
+ -- begin
+ -- ...
+
+ -- is converted to
+
+ -- declare
+ -- Result : T renames FuncRA.all;
+ -- [Result := <expression;]
+ -- begin
+ -- ...
+
+ declare
+ Return_Obj_Id : constant Entity_Id :=
+ Defining_Identifier (Return_Object_Decl);
+ Return_Obj_Typ : constant Entity_Id := Etype (Return_Obj_Id);
+ Return_Obj_Expr : constant Node_Id :=
+ Expression (Return_Object_Decl);
+ Result_Subt : constant Entity_Id :=
+ Etype (Parent_Function);
+ Constr_Result : constant Boolean :=
+ Is_Constrained (Result_Subt);
+ Obj_Alloc_Formal : Entity_Id;
+ Object_Access : Entity_Id;
+ Obj_Acc_Deref : Node_Id;
+ Init_Assignment : Node_Id := Empty;
+
+ begin
+ -- Build-in-place results must be returned by reference
+
+ Set_By_Ref (Return_Stm);
+
+ -- Retrieve the implicit access parameter passed by the caller
+
+ Object_Access :=
+ Build_In_Place_Formal (Parent_Function, BIP_Object_Access);
+
+ -- If the return object's declaration includes an expression
+ -- and the declaration isn't marked as No_Initialization, then
+ -- we need to generate an assignment to the object and insert
+ -- it after the declaration before rewriting it as a renaming
+ -- (otherwise we'll lose the initialization).
+
+ if Present (Return_Obj_Expr)
+ and then not No_Initialization (Return_Object_Decl)
+ then
+ Init_Assignment :=
+ Make_Assignment_Statement (Loc,
+ Name => New_Reference_To (Return_Obj_Id, Loc),
+ Expression => Relocate_Node (Return_Obj_Expr));
+ Set_Etype (Name (Init_Assignment), Etype (Return_Obj_Id));
+ Set_Assignment_OK (Name (Init_Assignment));
+ Set_No_Ctrl_Actions (Init_Assignment);
+
+ Set_Parent (Name (Init_Assignment), Init_Assignment);
+ Set_Parent (Expression (Init_Assignment), Init_Assignment);
+
+ Set_Expression (Return_Object_Decl, Empty);
+
+ if Is_Class_Wide_Type (Etype (Return_Obj_Id))
+ and then not Is_Class_Wide_Type
+ (Etype (Expression (Init_Assignment)))
+ then
+ Rewrite (Expression (Init_Assignment),
+ Make_Type_Conversion (Loc,
+ Subtype_Mark =>
+ New_Occurrence_Of
+ (Etype (Return_Obj_Id), Loc),
+ Expression =>
+ Relocate_Node (Expression (Init_Assignment))));
+ end if;
+
+ -- In the case of functions where the calling context can
+ -- determine the form of allocation needed, initialization
+ -- is done with each part of the if statement that handles
+ -- the different forms of allocation (this is true for
+ -- unconstrained and tagged result subtypes).
+
+ if Constr_Result
+ and then not Is_Tagged_Type (Underlying_Type (Result_Subt))
+ then
+ Insert_After (Return_Object_Decl, Init_Assignment);
+ end if;
+ end if;
+
+ -- When the function's subtype is unconstrained, a run-time
+ -- test is needed to determine the form of allocation to use
+ -- for the return object. The function has an implicit formal
+ -- parameter indicating this. If the BIP_Alloc_Form formal has
+ -- the value one, then the caller has passed access to an
+ -- existing object for use as the return object. If the value
+ -- is two, then the return object must be allocated on the
+ -- secondary stack. Otherwise, the object must be allocated in
+ -- a storage pool (currently only supported for the global
+ -- heap, user-defined storage pools TBD ???). We generate an
+ -- if statement to test the implicit allocation formal and
+ -- initialize a local access value appropriately, creating
+ -- allocators in the secondary stack and global heap cases.
+ -- The special formal also exists and must be tested when the
+ -- function has a tagged result, even when the result subtype
+ -- is constrained, because in general such functions can be
+ -- called in dispatching contexts and must be handled similarly
+ -- to functions with a class-wide result.
+
+ if not Constr_Result
+ or else Is_Tagged_Type (Underlying_Type (Result_Subt))
+ then
+ Obj_Alloc_Formal :=
+ Build_In_Place_Formal (Parent_Function, BIP_Alloc_Form);
+
+ declare
+ Ref_Type : Entity_Id;
+ Ptr_Type_Decl : Node_Id;
+ Alloc_Obj_Id : Entity_Id;
+ Alloc_Obj_Decl : Node_Id;
+ Alloc_If_Stmt : Node_Id;
+ SS_Allocator : Node_Id;
+ Heap_Allocator : Node_Id;
+
+ begin
+ -- Reuse the itype created for the function's implicit
+ -- access formal. This avoids the need to create a new
+ -- access type here, plus it allows assigning the access
+ -- formal directly without applying a conversion.
+
+ -- Ref_Type := Etype (Object_Access);
+
+ -- Create an access type designating the function's
+ -- result subtype.
+
+ Ref_Type :=
+ Make_Defining_Identifier (Loc, New_Internal_Name ('A'));
+
+ Ptr_Type_Decl :=
+ Make_Full_Type_Declaration (Loc,
+ Defining_Identifier => Ref_Type,
+ Type_Definition =>
+ Make_Access_To_Object_Definition (Loc,
+ All_Present => True,
+ Subtype_Indication =>
+ New_Reference_To (Return_Obj_Typ, Loc)));
+
+ Insert_Before (Return_Object_Decl, Ptr_Type_Decl);
+
+ -- Create an access object that will be initialized to an
+ -- access value denoting the return object, either coming
+ -- from an implicit access value passed in by the caller
+ -- or from the result of an allocator.
+
+ Alloc_Obj_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('R'));
+ Set_Etype (Alloc_Obj_Id, Ref_Type);
+
+ Alloc_Obj_Decl :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Alloc_Obj_Id,
+ Object_Definition => New_Reference_To
+ (Ref_Type, Loc));
+
+ Insert_Before (Return_Object_Decl, Alloc_Obj_Decl);
+
+ -- Create allocators for both the secondary stack and
+ -- global heap. If there's an initialization expression,
+ -- then create these as initialized allocators.
+
+ if Present (Return_Obj_Expr)
+ and then not No_Initialization (Return_Object_Decl)
+ then
+ Heap_Allocator :=
+ Make_Allocator (Loc,
+ Expression =>
+ Make_Qualified_Expression (Loc,
+ Subtype_Mark =>
+ New_Reference_To (Return_Obj_Typ, Loc),
+ Expression =>
+ New_Copy_Tree (Return_Obj_Expr)));
+
+ SS_Allocator := New_Copy_Tree (Heap_Allocator);
+
+ else
+ -- If the function returns a class-wide type we cannot
+ -- use the return type for the allocator. Instead we
+ -- use the type of the expression, which must be an
+ -- aggregate of a definite type.
+
+ if Is_Class_Wide_Type (Return_Obj_Typ) then
+ Heap_Allocator :=
+ Make_Allocator (Loc,
+ New_Reference_To
+ (Etype (Return_Obj_Expr), Loc));
+ else
+ Heap_Allocator :=
+ Make_Allocator (Loc,
+ New_Reference_To (Return_Obj_Typ, Loc));
+ end if;
+
+ -- If the object requires default initialization then
+ -- that will happen later following the elaboration of
+ -- the object renaming. If we don't turn it off here
+ -- then the object will be default initialized twice.
+
+ Set_No_Initialization (Heap_Allocator);
+
+ SS_Allocator := New_Copy_Tree (Heap_Allocator);
+ end if;
+
+ Set_Storage_Pool
+ (SS_Allocator, RTE (RE_SS_Pool));
+ Set_Procedure_To_Call
+ (SS_Allocator, RTE (RE_SS_Allocate));
+
+ -- The allocator is returned on the secondary stack,
+ -- so indicate that the function return, as well as
+ -- the block that encloses the allocator, must not
+ -- release it. The flags must be set now because the
+ -- decision to use the secondary stack is done very
+ -- late in the course of expanding the return statement,
+ -- past the point where these flags are normally set.
+
+ Set_Sec_Stack_Needed_For_Return (Parent_Function);
+ Set_Sec_Stack_Needed_For_Return
+ (Return_Statement_Entity (N));
+ Set_Uses_Sec_Stack (Parent_Function);
+ Set_Uses_Sec_Stack (Return_Statement_Entity (N));
+
+ -- Create an if statement to test the BIP_Alloc_Form
+ -- formal and initialize the access object to either the
+ -- BIP_Object_Access formal (BIP_Alloc_Form = 0), the
+ -- result of allocating the object in the secondary stack
+ -- (BIP_Alloc_Form = 1), or else an allocator to create
+ -- the return object in the heap (BIP_Alloc_Form = 2).
+
+ -- ??? An unchecked type conversion must be made in the
+ -- case of assigning the access object formal to the
+ -- local access object, because a normal conversion would
+ -- be illegal in some cases (such as converting access-
+ -- to-unconstrained to access-to-constrained), but the
+ -- the unchecked conversion will presumably fail to work
+ -- right in just such cases. It's not clear at all how to
+ -- handle this. ???
+
+ Alloc_If_Stmt :=
+ Make_If_Statement (Loc,
+ Condition =>
+ Make_Op_Eq (Loc,
+ Left_Opnd =>
+ New_Reference_To (Obj_Alloc_Formal, Loc),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ UI_From_Int (BIP_Allocation_Form'Pos
+ (Caller_Allocation)))),
+ Then_Statements =>
+ New_List (Make_Assignment_Statement (Loc,
+ Name =>
+ New_Reference_To
+ (Alloc_Obj_Id, Loc),
+ Expression =>
+ Make_Unchecked_Type_Conversion (Loc,
+ Subtype_Mark =>
+ New_Reference_To (Ref_Type, Loc),
+ Expression =>
+ New_Reference_To
+ (Object_Access, Loc)))),
+ Elsif_Parts =>
+ New_List (Make_Elsif_Part (Loc,
+ Condition =>
+ Make_Op_Eq (Loc,
+ Left_Opnd =>
+ New_Reference_To
+ (Obj_Alloc_Formal, Loc),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ UI_From_Int (
+ BIP_Allocation_Form'Pos
+ (Secondary_Stack)))),
+ Then_Statements =>
+ New_List
+ (Make_Assignment_Statement (Loc,
+ Name =>
+ New_Reference_To
+ (Alloc_Obj_Id, Loc),
+ Expression =>
+ SS_Allocator)))),
+ Else_Statements =>
+ New_List (Make_Assignment_Statement (Loc,
+ Name =>
+ New_Reference_To
+ (Alloc_Obj_Id, Loc),
+ Expression =>
+ Heap_Allocator)));
+
+ -- If a separate initialization assignment was created
+ -- earlier, append that following the assignment of the
+ -- implicit access formal to the access object, to ensure
+ -- that the return object is initialized in that case.
+ -- In this situation, the target of the assignment must
+ -- be rewritten to denote a derference of the access to
+ -- the return object passed in by the caller.
+
+ if Present (Init_Assignment) then
+ Rewrite (Name (Init_Assignment),
+ Make_Explicit_Dereference (Loc,
+ Prefix => New_Reference_To (Alloc_Obj_Id, Loc)));
+ Set_Etype
+ (Name (Init_Assignment), Etype (Return_Obj_Id));
+
+ Append_To
+ (Then_Statements (Alloc_If_Stmt),
+ Init_Assignment);
+ end if;
+
+ Insert_Before (Return_Object_Decl, Alloc_If_Stmt);
+
+ -- Remember the local access object for use in the
+ -- dereference of the renaming created below.
+
+ Object_Access := Alloc_Obj_Id;
+ end;
+ end if;
+
+ -- Replace the return object declaration with a renaming of a
+ -- dereference of the access value designating the return
+ -- object.
+
+ Obj_Acc_Deref :=
+ Make_Explicit_Dereference (Loc,
+ Prefix => New_Reference_To (Object_Access, Loc));
+
+ Rewrite (Return_Object_Decl,
+ Make_Object_Renaming_Declaration (Loc,
+ Defining_Identifier => Return_Obj_Id,
+ Access_Definition => Empty,
+ Subtype_Mark => New_Occurrence_Of
+ (Return_Obj_Typ, Loc),
+ Name => Obj_Acc_Deref));
+
+ Set_Renamed_Object (Return_Obj_Id, Obj_Acc_Deref);
+ end;
+ end if;
+
+ -- Case where we do not build a block
+
+ else
+ -- We're about to drop Return_Object_Declarations on the floor, so
+ -- we need to insert it, in case it got expanded into useful code.
+
+ Insert_List_Before (N, Return_Object_Declarations (N));
+
+ -- Build simple_return_statement that returns the expression directly
+
+ Return_Stm := Make_Simple_Return_Statement (Loc, Expression => Exp);
+
+ Result := Return_Stm;
+ end if;
+
+ -- Set the flag to prevent infinite recursion
+
+ Set_Comes_From_Extended_Return_Statement (Return_Stm);
+
+ Rewrite (N, Result);
+ Analyze (N);
+ end Expand_N_Extended_Return_Statement;
+
-----------------------------
-- Expand_N_Goto_Statement --
-----------------------------
-- Expand_N_If_Statement --
---------------------------
- -- First we deal with the case of C and Fortran convention boolean
- -- values, with zero/non-zero semantics.
+ -- First we deal with the case of C and Fortran convention boolean values,
+ -- with zero/non-zero semantics.
-- Second, we deal with the obvious rewriting for the cases where the
-- condition of the IF is known at compile time to be True or False.
-- end if;
-- This rewriting is needed if at least one elsif part has a non-empty
- -- Condition_Actions list. We also do the same processing if there is
- -- a constant condition in an elsif part (in conjunction with the first
+ -- Condition_Actions list. We also do the same processing if there is a
+ -- constant condition in an elsif part (in conjunction with the first
-- processing step mentioned above, for the recursive call made to deal
-- with the created inner if, this deals with properly optimizing the
-- cases of constant elsif conditions).
E : Node_Id;
New_If : Node_Id;
+ Warn_If_Deleted : constant Boolean :=
+ Warn_On_Deleted_Code and then Comes_From_Source (N);
+ -- Indicates whether we want warnings when we delete branches of the
+ -- if statement based on constant condition analysis. We never want
+ -- these warnings for expander generated code.
+
begin
Adjust_Condition (Condition (N));
while Compile_Time_Known_Value (Condition (N)) loop
- -- If condition is True, we can simply rewrite the if statement
- -- now by replacing it by the series of then statements.
+ -- If condition is True, we can simply rewrite the if statement now
+ -- by replacing it by the series of then statements.
if Is_True (Expr_Value (Condition (N))) then
-- All the else parts can be killed
- Kill_Dead_Code (Elsif_Parts (N));
- Kill_Dead_Code (Else_Statements (N));
+ Kill_Dead_Code (Elsif_Parts (N), Warn_If_Deleted);
+ Kill_Dead_Code (Else_Statements (N), Warn_If_Deleted);
Hed := Remove_Head (Then_Statements (N));
Insert_List_After (N, Then_Statements (N));
-- the Then statements
else
- -- We do not delete the condition if constant condition
- -- warnings are enabled, since otherwise we end up deleting
- -- the desired warning. Of course the backend will get rid
- -- of this True/False test anyway, so nothing is lost here.
+ -- We do not delete the condition if constant condition warnings
+ -- are enabled, since otherwise we end up deleting the desired
+ -- warning. Of course the backend will get rid of this True/False
+ -- test anyway, so nothing is lost here.
if not Constant_Condition_Warnings then
Kill_Dead_Code (Condition (N));
end if;
- Kill_Dead_Code (Then_Statements (N));
+ Kill_Dead_Code (Then_Statements (N), Warn_If_Deleted);
- -- If there are no elsif statements, then we simply replace
- -- the entire if statement by the sequence of else statements.
+ -- If there are no elsif statements, then we simply replace the
+ -- entire if statement by the sequence of else statements.
if No (Elsif_Parts (N)) then
-
if No (Else_Statements (N))
or else Is_Empty_List (Else_Statements (N))
then
Rewrite (N,
Make_Null_Statement (Sloc (N)));
-
else
Hed := Remove_Head (Else_Statements (N));
Insert_List_After (N, Else_Statements (N));
return;
- -- If there are elsif statements, the first of them becomes
- -- the if/then section of the rebuilt if statement This is
- -- the case where we loop to reprocess this copied condition.
+ -- If there are elsif statements, the first of them becomes the
+ -- if/then section of the rebuilt if statement This is the case
+ -- where we loop to reprocess this copied condition.
else
Hed := Remove_Head (Elsif_Parts (N));
Set_Condition (N, Condition (Hed));
Set_Then_Statements (N, Then_Statements (Hed));
+ -- Hed might have been captured as the condition determining
+ -- the current value for an entity. Now it is detached from
+ -- the tree, so a Current_Value pointer in the condition might
+ -- need to be updated.
+
+ Set_Current_Value_Condition (N);
+
if Is_Empty_List (Elsif_Parts (N)) then
Set_Elsif_Parts (N, No_List);
end if;
while Present (E) loop
Adjust_Condition (Condition (E));
- -- If there are condition actions, then we rewrite the if
- -- statement as indicated above. We also do the same rewrite
- -- if the condition is True or False. The further processing
- -- of this constant condition is then done by the recursive
- -- call to expand the newly created if statement
+ -- If there are condition actions, then rewrite the if statement
+ -- as indicated above. We also do the same rewrite for a True or
+ -- False condition. The further processing of this constant
+ -- condition is then done by the recursive call to expand the
+ -- newly created if statement
if Present (Condition_Actions (E))
or else Compile_Time_Known_Value (Condition (E))
then
- -- Note this is not an implicit if statement, since it is
- -- part of an explicit if statement in the source (or of an
- -- implicit if statement that has already been tested).
+ -- Note this is not an implicit if statement, since it is part
+ -- of an explicit if statement in the source (or of an implicit
+ -- if statement that has already been tested).
New_If :=
Make_If_Statement (Sloc (E),
Else_Stm : constant Node_Id := First (Else_Statements (N));
begin
- if Nkind (Then_Stm) = N_Return_Statement
+ if Nkind (Then_Stm) = N_Simple_Return_Statement
and then
- Nkind (Else_Stm) = N_Return_Statement
+ Nkind (Else_Stm) = N_Simple_Return_Statement
then
declare
Then_Expr : constant Node_Id := Expression (Then_Stm);
and then Entity (Else_Expr) = Standard_False
then
Rewrite (N,
- Make_Return_Statement (Loc,
+ Make_Simple_Return_Statement (Loc,
Expression => Relocate_Node (Condition (N))));
Analyze (N);
return;
and then Entity (Else_Expr) = Standard_True
then
Rewrite (N,
- Make_Return_Statement (Loc,
+ Make_Simple_Return_Statement (Loc,
Expression =>
Make_Op_Not (Loc,
Right_Opnd => Relocate_Node (Condition (N)))));
Generate_Poll_Call (First (Statements (N)));
end if;
+ -- Nothing more to do for plain loop with no iteration scheme
+
if No (Isc) then
return;
end if;
- -- Handle the case where we have a for loop with the range type being
- -- an enumeration type with non-standard representation. In this case
- -- we expand:
+ -- Note: we do not have to worry about validity chekcing of the for loop
+ -- range bounds here, since they were frozen with constant declarations
+ -- and it is during that process that the validity checking is done.
+
+ -- Handle the case where we have a for loop with the range type being an
+ -- enumeration type with non-standard representation. In this case we
+ -- expand:
-- for x in [reverse] a .. b loop
-- ...
Make_Defining_Identifier (Loc,
Chars => New_External_Name (Chars (Loop_Id), 'P'));
- -- If the type has a contiguous representation, successive
- -- values can be generated as offsets from the first literal.
+ -- If the type has a contiguous representation, successive values
+ -- can be generated as offsets from the first literal.
if Has_Contiguous_Rep (Btype) then
Expr :=
Enumeration_Rep (First_Literal (Btype))),
Right_Opnd => New_Reference_To (New_Id, Loc)));
else
- -- Use the constructed array Enum_Pos_To_Rep.
+ -- Use the constructed array Enum_Pos_To_Rep
Expr :=
Make_Indexed_Component (Loc,
Analyze (N);
end;
- -- Second case, if we have a while loop with Condition_Actions set,
- -- then we change it into a plain loop:
+ -- Second case, if we have a while loop with Condition_Actions set, then
+ -- we change it into a plain loop:
-- while C loop
-- ...
Prepend (ES, Statements (N));
Insert_List_Before (ES, Condition_Actions (Isc));
- -- This is not an implicit loop, since it is generated in
- -- response to the loop statement being processed. If this
- -- is itself implicit, the restriction has already been
- -- checked. If not, it is an explicit loop.
+ -- This is not an implicit loop, since it is generated in response
+ -- to the loop statement being processed. If this is itself
+ -- implicit, the restriction has already been checked. If not,
+ -- it is an explicit loop.
Rewrite (N,
Make_Loop_Statement (Sloc (N),
end if;
end Expand_N_Loop_Statement;
- -------------------------------
- -- Expand_N_Return_Statement --
- -------------------------------
-
- procedure Expand_N_Return_Statement (N : Node_Id) is
- Loc : constant Source_Ptr := Sloc (N);
- Exp : constant Node_Id := Expression (N);
- Exptyp : Entity_Id;
- T : Entity_Id;
- Utyp : Entity_Id;
- Scope_Id : Entity_Id;
- Kind : Entity_Kind;
- Call : Node_Id;
- Acc_Stat : Node_Id;
- Goto_Stat : Node_Id;
- Lab_Node : Node_Id;
- Cur_Idx : Nat;
- Return_Type : Entity_Id;
- Result_Exp : Node_Id;
- Result_Id : Entity_Id;
- Result_Obj : Node_Id;
+ --------------------------------------
+ -- Expand_N_Simple_Return_Statement --
+ --------------------------------------
+ procedure Expand_N_Simple_Return_Statement (N : Node_Id) is
begin
- -- Case where returned expression is present
+ -- Distinguish the function and non-function cases:
- if Present (Exp) then
+ case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is
- -- Always normalize C/Fortran boolean result. This is not always
- -- necessary, but it seems a good idea to minimize the passing
- -- around of non-normalized values, and in any case this handles
- -- the processing of barrier functions for protected types, which
- -- turn the condition into a return statement.
+ when E_Function |
+ E_Generic_Function =>
+ Expand_Simple_Function_Return (N);
- Exptyp := Etype (Exp);
-
- if Is_Boolean_Type (Exptyp)
- and then Nonzero_Is_True (Exptyp)
- then
- Adjust_Condition (Exp);
- Adjust_Result_Type (Exp, Exptyp);
- end if;
+ when E_Procedure |
+ E_Generic_Procedure |
+ E_Entry |
+ E_Entry_Family |
+ E_Return_Statement =>
+ Expand_Non_Function_Return (N);
- -- Do validity check if enabled for returns
+ when others =>
+ raise Program_Error;
+ end case;
- if Validity_Checks_On
- and then Validity_Check_Returns
- then
- Ensure_Valid (Exp);
- end if;
- end if;
+ exception
+ when RE_Not_Available =>
+ return;
+ end Expand_N_Simple_Return_Statement;
- -- Find relevant enclosing scope from which return is returning
+ --------------------------------
+ -- Expand_Non_Function_Return --
+ --------------------------------
- Cur_Idx := Scope_Stack.Last;
- loop
- Scope_Id := Scope_Stack.Table (Cur_Idx).Entity;
+ procedure Expand_Non_Function_Return (N : Node_Id) is
+ pragma Assert (No (Expression (N)));
- if Ekind (Scope_Id) /= E_Block
- and then Ekind (Scope_Id) /= E_Loop
- then
- exit;
+ Loc : constant Source_Ptr := Sloc (N);
+ Scope_Id : Entity_Id :=
+ Return_Applies_To (Return_Statement_Entity (N));
+ Kind : constant Entity_Kind := Ekind (Scope_Id);
+ Call : Node_Id;
+ Acc_Stat : Node_Id;
+ Goto_Stat : Node_Id;
+ Lab_Node : Node_Id;
- else
- Cur_Idx := Cur_Idx - 1;
- pragma Assert (Cur_Idx >= 0);
- end if;
- end loop;
+ begin
+ -- If it is a return from a procedure do no extra steps
- if No (Exp) then
- Kind := Ekind (Scope_Id);
+ if Kind = E_Procedure or else Kind = E_Generic_Procedure then
+ return;
- -- If it is a return from procedures do no extra steps.
+ -- If it is a nested return within an extended one, replace it with a
+ -- return of the previously declared return object.
- if Kind = E_Procedure or else Kind = E_Generic_Procedure then
- return;
- end if;
+ elsif Kind = E_Return_Statement then
+ Rewrite (N,
+ Make_Simple_Return_Statement (Loc,
+ Expression =>
+ New_Occurrence_Of (First_Entity (Scope_Id), Loc)));
+ Set_Comes_From_Extended_Return_Statement (N);
+ Set_Return_Statement_Entity (N, Scope_Id);
+ Expand_Simple_Function_Return (N);
+ return;
+ end if;
- pragma Assert (Is_Entry (Scope_Id));
+ pragma Assert (Is_Entry (Scope_Id));
- -- Look at the enclosing block to see whether the return is from
- -- an accept statement or an entry body.
+ -- Look at the enclosing block to see whether the return is from an
+ -- accept statement or an entry body.
- for J in reverse 0 .. Cur_Idx loop
- Scope_Id := Scope_Stack.Table (J).Entity;
- exit when Is_Concurrent_Type (Scope_Id);
- end loop;
+ for J in reverse 0 .. Scope_Stack.Last loop
+ Scope_Id := Scope_Stack.Table (J).Entity;
+ exit when Is_Concurrent_Type (Scope_Id);
+ end loop;
- -- If it is a return from accept statement it should be expanded
- -- as a call to RTS Complete_Rendezvous and a goto to the end of
- -- the accept body.
+ -- If it is a return from accept statement it is expanded as call to
+ -- RTS Complete_Rendezvous and a goto to the end of the accept body.
- -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
- -- Expand_N_Accept_Alternative in exp_ch9.adb)
+ -- (cf : Expand_N_Accept_Statement, Expand_N_Selective_Accept,
+ -- Expand_N_Accept_Alternative in exp_ch9.adb)
- if Is_Task_Type (Scope_Id) then
+ if Is_Task_Type (Scope_Id) then
- Call := (Make_Procedure_Call_Statement (Loc,
- Name => New_Reference_To
- (RTE (RE_Complete_Rendezvous), Loc)));
- Insert_Before (N, Call);
- -- why not insert actions here???
- Analyze (Call);
+ Call :=
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To
+ (RTE (RE_Complete_Rendezvous), Loc));
+ Insert_Before (N, Call);
+ -- why not insert actions here???
+ Analyze (Call);
- Acc_Stat := Parent (N);
- while Nkind (Acc_Stat) /= N_Accept_Statement loop
- Acc_Stat := Parent (Acc_Stat);
- end loop;
+ Acc_Stat := Parent (N);
+ while Nkind (Acc_Stat) /= N_Accept_Statement loop
+ Acc_Stat := Parent (Acc_Stat);
+ end loop;
- Lab_Node := Last (Statements
- (Handled_Statement_Sequence (Acc_Stat)));
+ Lab_Node := Last (Statements
+ (Handled_Statement_Sequence (Acc_Stat)));
- Goto_Stat := Make_Goto_Statement (Loc,
- Name => New_Occurrence_Of
- (Entity (Identifier (Lab_Node)), Loc));
+ Goto_Stat := Make_Goto_Statement (Loc,
+ Name => New_Occurrence_Of
+ (Entity (Identifier (Lab_Node)), Loc));
- Set_Analyzed (Goto_Stat);
+ Set_Analyzed (Goto_Stat);
- Rewrite (N, Goto_Stat);
- Analyze (N);
+ Rewrite (N, Goto_Stat);
+ Analyze (N);
- -- If it is a return from an entry body, put a Complete_Entry_Body
- -- call in front of the return.
+ -- If it is a return from an entry body, put a Complete_Entry_Body call
+ -- in front of the return.
- elsif Is_Protected_Type (Scope_Id) then
+ elsif Is_Protected_Type (Scope_Id) then
+ Call :=
+ Make_Procedure_Call_Statement (Loc,
+ Name => New_Reference_To
+ (RTE (RE_Complete_Entry_Body), Loc),
+ Parameter_Associations => New_List
+ (Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Reference_To
+ (Object_Ref
+ (Corresponding_Body (Parent (Scope_Id))),
+ Loc),
+ Attribute_Name => Name_Unchecked_Access)));
+
+ Insert_Before (N, Call);
+ Analyze (Call);
+ end if;
+ end Expand_Non_Function_Return;
- Call :=
- Make_Procedure_Call_Statement (Loc,
- Name => New_Reference_To
- (RTE (RE_Complete_Entry_Body), Loc),
- Parameter_Associations => New_List
- (Make_Attribute_Reference (Loc,
- Prefix =>
- New_Reference_To
- (Object_Ref
- (Corresponding_Body (Parent (Scope_Id))),
- Loc),
- Attribute_Name => Name_Unchecked_Access)));
+ -----------------------------------
+ -- Expand_Simple_Function_Return --
+ -----------------------------------
- Insert_Before (N, Call);
- Analyze (Call);
+ -- The "simple" comes from the syntax rule simple_return_statement.
+ -- The semantics are not at all simple!
- end if;
+ procedure Expand_Simple_Function_Return (N : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
- return;
- end if;
+ Scope_Id : constant Entity_Id :=
+ Return_Applies_To (Return_Statement_Entity (N));
+ -- The function we are returning from
- T := Etype (Exp);
- Return_Type := Etype (Scope_Id);
- Utyp := Underlying_Type (Return_Type);
+ R_Type : constant Entity_Id := Etype (Scope_Id);
+ -- The result type of the function
- -- Check the result expression of a scalar function against
- -- the subtype of the function by inserting a conversion.
- -- This conversion must eventually be performed for other
- -- classes of types, but for now it's only done for scalars.
- -- ???
+ Utyp : constant Entity_Id := Underlying_Type (R_Type);
- if Is_Scalar_Type (T) then
- Rewrite (Exp, Convert_To (Return_Type, Exp));
- Analyze (Exp);
- end if;
+ Exp : constant Node_Id := Expression (N);
+ pragma Assert (Present (Exp));
- -- Implement the rules of 6.5(8-10), which require a tag check in
- -- the case of a limited tagged return type, and tag reassignment
- -- for nonlimited tagged results. These actions are needed when
- -- the return type is a specific tagged type and the result
- -- expression is a conversion or a formal parameter, because in
- -- that case the tag of the expression might differ from the tag
- -- of the specific result type.
+ Exptyp : constant Entity_Id := Etype (Exp);
+ -- The type of the expression (not necessarily the same as R_Type)
- if Is_Tagged_Type (Utyp)
- and then not Is_Class_Wide_Type (Utyp)
- and then (Nkind (Exp) = N_Type_Conversion
- or else Nkind (Exp) = N_Unchecked_Type_Conversion
- or else (Is_Entity_Name (Exp)
- and then Ekind (Entity (Exp)) in Formal_Kind))
+ begin
+ -- We rewrite "return <expression>;" to be:
+
+ -- return _anon_ : <return_subtype> := <expression>
+
+ -- The expansion produced by Expand_N_Extended_Return_Statement will
+ -- contain simple return statements (for example, a block containing
+ -- simple return of the return object), which brings us back here with
+ -- Comes_From_Extended_Return_Statement set. To avoid infinite
+ -- recursion, we do not transform into an extended return if
+ -- Comes_From_Extended_Return_Statement is True.
+
+ -- The reason for this design is that for Ada 2005 limited returns, we
+ -- need to reify the return object, so we can build it "in place", and
+ -- we need a block statement to hang finalization and tasking stuff.
+
+ -- ??? In order to avoid disruption, we avoid translating to extended
+ -- return except in the cases where we really need to (Ada 2005
+ -- inherently limited). We would prefer eventually to do this
+ -- translation in all cases except perhaps for the case of Ada 95
+ -- inherently limited, in order to fully exercise the code in
+ -- Expand_N_Extended_Return_Statement, and in order to do
+ -- build-in-place for efficiency when it is not required.
+
+ -- As before, we check the type of the return expression rather than the
+ -- return type of the function, because the latter may be a limited
+ -- class-wide interface type, which is not a limited type, even though
+ -- the type of the expression may be.
+
+ if not Comes_From_Extended_Return_Statement (N)
+ and then Is_Inherently_Limited_Type (Etype (Expression (N)))
+ and then Ada_Version >= Ada_05 -- ???
+ and then not Debug_Flag_Dot_L
then
- -- When the return type is limited, perform a check that the
- -- tag of the result is the same as the tag of the return type.
-
- if Is_Limited_Type (Return_Type) then
- Insert_Action (Exp,
- Make_Raise_Constraint_Error (Loc,
- Condition =>
- Make_Op_Ne (Loc,
- Left_Opnd =>
- Make_Selected_Component (Loc,
- Prefix => Duplicate_Subexpr (Exp),
- Selector_Name =>
- New_Reference_To (Tag_Component (Utyp), Loc)),
- Right_Opnd =>
- Unchecked_Convert_To (RTE (RE_Tag),
- New_Reference_To
- (Access_Disp_Table (Base_Type (Utyp)), Loc))),
- Reason => CE_Tag_Check_Failed));
+ declare
+ Return_Object_Entity : constant Entity_Id :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('R'));
- -- If the result type is a specific nonlimited tagged type,
- -- then we have to ensure that the tag of the result is that
- -- of the result type. This is handled by making a copy of the
- -- expression in the case where it might have a different tag,
- -- namely when the expression is a conversion or a formal
- -- parameter. We create a new object of the result type and
- -- initialize it from the expression, which will implicitly
- -- force the tag to be set appropriately.
+ Subtype_Ind : constant Node_Id := New_Occurrence_Of (R_Type, Loc);
- else
- Result_Id :=
- Make_Defining_Identifier (Loc, New_Internal_Name ('R'));
- Result_Exp := New_Reference_To (Result_Id, Loc);
-
- Result_Obj :=
- Make_Object_Declaration (Loc,
- Defining_Identifier => Result_Id,
- Object_Definition => New_Reference_To (Return_Type, Loc),
- Constant_Present => True,
- Expression => Relocate_Node (Exp));
+ Obj_Decl : constant Node_Id :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Return_Object_Entity,
+ Object_Definition => Subtype_Ind,
+ Expression => Exp);
- Set_Assignment_OK (Result_Obj);
- Insert_Action (Exp, Result_Obj);
+ Ext : constant Node_Id := Make_Extended_Return_Statement (Loc,
+ Return_Object_Declarations => New_List (Obj_Decl));
- Rewrite (Exp, Result_Exp);
- Analyze_And_Resolve (Exp, Return_Type);
- end if;
+ begin
+ Rewrite (N, Ext);
+ Analyze (N);
+ return;
+ end;
end if;
- -- Deal with returning variable length objects and controlled types
+ -- Here we have a simple return statement that is part of the expansion
+ -- of an extended return statement (either written by the user, or
+ -- generated by the above code).
- -- Nothing to do if we are returning by reference, or this is not
- -- a type that requires special processing (indicated by the fact
- -- that it requires a cleanup scope for the secondary stack case)
+ -- Always normalize C/Fortran boolean result. This is not always needed,
+ -- but it seems a good idea to minimize the passing around of non-
+ -- normalized values, and in any case this handles the processing of
+ -- barrier functions for protected types, which turn the condition into
+ -- a return statement.
- if Is_Return_By_Reference_Type (T)
- or else not Requires_Transient_Scope (Return_Type)
+ if Is_Boolean_Type (Exptyp)
+ and then Nonzero_Is_True (Exptyp)
then
- null;
-
- -- Case of secondary stack not used
-
- elsif Function_Returns_With_DSP (Scope_Id) then
-
- -- Here what we need to do is to always return by reference, since
- -- we will return with the stack pointer depressed. We may need to
- -- do a copy to a local temporary before doing this return.
-
- No_Secondary_Stack_Case : declare
- Local_Copy_Required : Boolean := False;
- -- Set to True if a local copy is required
-
- Copy_Ent : Entity_Id;
- -- Used for the target entity if a copy is required
-
- Decl : Node_Id;
- -- Declaration used to create copy if needed
-
- procedure Test_Copy_Required (Expr : Node_Id);
- -- Determines if Expr represents a return value for which a
- -- copy is required. More specifically, a copy is not required
- -- if Expr represents an object or component of an object that
- -- is either in the local subprogram frame, or is constant.
- -- If a copy is required, then Local_Copy_Required is set True.
-
- ------------------------
- -- Test_Copy_Required --
- ------------------------
-
- procedure Test_Copy_Required (Expr : Node_Id) is
- Ent : Entity_Id;
-
- begin
- -- If component, test prefix (object containing component)
-
- if Nkind (Expr) = N_Indexed_Component
- or else
- Nkind (Expr) = N_Selected_Component
- then
- Test_Copy_Required (Prefix (Expr));
- return;
+ Adjust_Condition (Exp);
+ Adjust_Result_Type (Exp, Exptyp);
+ end if;
- -- See if we have an entity name
+ -- Do validity check if enabled for returns
- elsif Is_Entity_Name (Expr) then
- Ent := Entity (Expr);
+ if Validity_Checks_On
+ and then Validity_Check_Returns
+ then
+ Ensure_Valid (Exp);
+ end if;
- -- Constant entity is always OK, no copy required
+ -- Check the result expression of a scalar function against the subtype
+ -- of the function by inserting a conversion. This conversion must
+ -- eventually be performed for other classes of types, but for now it's
+ -- only done for scalars.
+ -- ???
- if Ekind (Ent) = E_Constant then
- return;
+ if Is_Scalar_Type (Exptyp) then
+ Rewrite (Exp, Convert_To (R_Type, Exp));
+ Analyze (Exp);
+ end if;
- -- No copy required for local variable
+ -- Deal with returning variable length objects and controlled types
- elsif Ekind (Ent) = E_Variable
- and then Scope (Ent) = Current_Subprogram
- then
- return;
- end if;
- end if;
+ -- Nothing to do if we are returning by reference, or this is not a
+ -- type that requires special processing (indicated by the fact that
+ -- it requires a cleanup scope for the secondary stack case).
- -- All other cases require a copy
+ if Is_Inherently_Limited_Type (Exptyp)
+ or else Is_Limited_Interface (Exptyp)
+ then
+ null;
- Local_Copy_Required := True;
- end Test_Copy_Required;
+ elsif not Requires_Transient_Scope (R_Type) then
- -- Start of processing for No_Secondary_Stack_Case
+ -- Mutable records with no variable length components are not
+ -- returned on the sec-stack, so we need to make sure that the
+ -- backend will only copy back the size of the actual value, and not
+ -- the maximum size. We create an actual subtype for this purpose.
+ declare
+ Ubt : constant Entity_Id := Underlying_Type (Base_Type (Exptyp));
+ Decl : Node_Id;
+ Ent : Entity_Id;
begin
- -- No copy needed if result is from a function call.
- -- In this case the result is already being returned by
- -- reference with the stack pointer depressed.
-
- -- To make up for a gcc 2.8.1 deficiency (???), we perform
- -- the copy for array types if the constrained status of the
- -- target type is different from that of the expression.
-
- if Requires_Transient_Scope (T)
- and then
- (not Is_Array_Type (T)
- or else Is_Constrained (T) = Is_Constrained (Return_Type)
- or else Controlled_Type (T))
- and then Nkind (Exp) = N_Function_Call
+ if Has_Discriminants (Ubt)
+ and then not Is_Constrained (Ubt)
+ and then not Has_Unchecked_Union (Ubt)
then
- Set_By_Ref (N);
-
- -- We always need a local copy for a controlled type, since
- -- we are required to finalize the local value before return.
- -- The copy will automatically include the required finalize.
- -- Moreover, gigi cannot make this copy, since we need special
- -- processing to ensure proper behavior for finalization.
-
- -- Note: the reason we are returning with a depressed stack
- -- pointer in the controlled case (even if the type involved
- -- is constrained) is that we must make a local copy to deal
- -- properly with the requirement that the local result be
- -- finalized.
-
- elsif Controlled_Type (Utyp) then
- Copy_Ent :=
- Make_Defining_Identifier (Loc,
- Chars => New_Internal_Name ('R'));
-
- -- Build declaration to do the copy, and insert it, setting
- -- Assignment_OK, because we may be copying a limited type.
- -- In addition we set the special flag to inhibit finalize
- -- attachment if this is a controlled type (since this attach
- -- must be done by the caller, otherwise if we attach it here
- -- we will finalize the returned result prematurely).
-
- Decl :=
- Make_Object_Declaration (Loc,
- Defining_Identifier => Copy_Ent,
- Object_Definition => New_Occurrence_Of (Return_Type, Loc),
- Expression => Relocate_Node (Exp));
-
- Set_Assignment_OK (Decl);
- Set_Delay_Finalize_Attach (Decl);
- Insert_Action (N, Decl);
-
- -- Now the actual return uses the copied value
-
- Rewrite (Exp, New_Occurrence_Of (Copy_Ent, Loc));
- Analyze_And_Resolve (Exp, Return_Type);
-
- -- Since we have made the copy, gigi does not have to, so
- -- we set the By_Ref flag to prevent another copy being made.
-
- Set_By_Ref (N);
-
- -- Non-controlled cases
-
- else
- Test_Copy_Required (Exp);
-
- -- If a local copy is required, then gigi will make the
- -- copy, otherwise, we can return the result directly,
- -- so set By_Ref to suppress the gigi copy.
-
- if not Local_Copy_Required then
- Set_By_Ref (N);
- end if;
+ Decl := Build_Actual_Subtype (Ubt, Exp);
+ Ent := Defining_Identifier (Decl);
+ Insert_Action (Exp, Decl);
+ Rewrite (Exp, Unchecked_Convert_To (Ent, Exp));
+ Analyze_And_Resolve (Exp);
end if;
- end No_Secondary_Stack_Case;
+ end;
-- Here if secondary stack is used
else
- -- Make sure that no surrounding block will reclaim the
- -- secondary-stack on which we are going to put the result.
- -- Not only may this introduce secondary stack leaks but worse,
- -- if the reclamation is done too early, then the result we are
- -- returning may get clobbered. See example in 7417-003.
+ -- Make sure that no surrounding block will reclaim the secondary
+ -- stack on which we are going to put the result. Not only may this
+ -- introduce secondary stack leaks but worse, if the reclamation is
+ -- done too early, then the result we are returning may get
+ -- clobbered.
declare
- S : Entity_Id := Current_Scope;
-
+ S : Entity_Id;
begin
+ S := Current_Scope;
while Ekind (S) = E_Block or else Ekind (S) = E_Loop loop
Set_Sec_Stack_Needed_For_Return (S, True);
S := Enclosing_Dynamic_Scope (S);
-- the copy for array types if the constrained status of the
-- target type is different from that of the expression.
- if Requires_Transient_Scope (T)
+ if Requires_Transient_Scope (Exptyp)
and then
- (not Is_Array_Type (T)
- or else Is_Constrained (T) = Is_Constrained (Return_Type)
- or else Controlled_Type (T))
+ (not Is_Array_Type (Exptyp)
+ or else Is_Constrained (Exptyp) = Is_Constrained (R_Type)
+ or else CW_Or_Controlled_Type (Utyp))
and then Nkind (Exp) = N_Function_Call
then
Set_By_Ref (N);
- -- For controlled types, do the allocation on the sec-stack
- -- manually in order to call adjust at the right time
- -- type Anon1 is access Return_Type;
+ -- Remove side effects from the expression now so that other parts
+ -- of the expander do not have to reanalyze this node without this
+ -- optimization
+
+ Rewrite (Exp, Duplicate_Subexpr_No_Checks (Exp));
+
+ -- For controlled types, do the allocation on the secondary stack
+ -- manually in order to call adjust at the right time:
+
+ -- type Anon1 is access R_Type;
-- for Anon1'Storage_pool use ss_pool;
- -- Anon2 : anon1 := new Return_Type'(expr);
+ -- Anon2 : anon1 := new R_Type'(expr);
-- return Anon2.all;
- elsif Controlled_Type (Utyp) then
+ -- We do the same for classwide types that are not potentially
+ -- controlled (by the virtue of restriction No_Finalization) because
+ -- gigi is not able to properly allocate class-wide types.
+
+ elsif CW_Or_Controlled_Type (Utyp) then
declare
Loc : constant Source_Ptr := Sloc (N);
Temp : constant Entity_Id :=
Type_Definition =>
Make_Access_To_Object_Definition (Loc,
Subtype_Indication =>
- New_Reference_To (Return_Type, Loc))),
+ New_Reference_To (R_Type, Loc))),
Make_Object_Declaration (Loc,
Defining_Identifier => Temp,
Make_Explicit_Dereference (Loc,
Prefix => New_Reference_To (Temp, Loc)));
- Analyze_And_Resolve (Exp, Return_Type);
+ Analyze_And_Resolve (Exp, R_Type);
end;
-- Otherwise use the gigi mechanism to allocate result on the
else
Set_Storage_Pool (N, RTE (RE_SS_Pool));
- -- If we are generating code for the Java VM do not use
+ -- If we are generating code for the VM do not use
-- SS_Allocate since everything is heap-allocated anyway.
- if not Java_VM then
+ if VM_Target = No_VM then
Set_Procedure_To_Call (N, RTE (RE_SS_Allocate));
end if;
end if;
end if;
- exception
- when RE_Not_Available =>
- return;
- end Expand_N_Return_Statement;
+ -- Implement the rules of 6.5(8-10), which require a tag check in the
+ -- case of a limited tagged return type, and tag reassignment for
+ -- nonlimited tagged results. These actions are needed when the return
+ -- type is a specific tagged type and the result expression is a
+ -- conversion or a formal parameter, because in that case the tag of the
+ -- expression might differ from the tag of the specific result type.
+
+ if Is_Tagged_Type (Utyp)
+ and then not Is_Class_Wide_Type (Utyp)
+ and then (Nkind (Exp) = N_Type_Conversion
+ or else Nkind (Exp) = N_Unchecked_Type_Conversion
+ or else (Is_Entity_Name (Exp)
+ and then Ekind (Entity (Exp)) in Formal_Kind))
+ then
+ -- When the return type is limited, perform a check that the
+ -- tag of the result is the same as the tag of the return type.
+
+ if Is_Limited_Type (R_Type) then
+ Insert_Action (Exp,
+ Make_Raise_Constraint_Error (Loc,
+ Condition =>
+ Make_Op_Ne (Loc,
+ Left_Opnd =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr (Exp),
+ Selector_Name =>
+ New_Reference_To (First_Tag_Component (Utyp), Loc)),
+ Right_Opnd =>
+ Unchecked_Convert_To (RTE (RE_Tag),
+ New_Reference_To
+ (Node (First_Elmt
+ (Access_Disp_Table (Base_Type (Utyp)))),
+ Loc))),
+ Reason => CE_Tag_Check_Failed));
+
+ -- If the result type is a specific nonlimited tagged type, then we
+ -- have to ensure that the tag of the result is that of the result
+ -- type. This is handled by making a copy of the expression in the
+ -- case where it might have a different tag, namely when the
+ -- expression is a conversion or a formal parameter. We create a new
+ -- object of the result type and initialize it from the expression,
+ -- which will implicitly force the tag to be set appropriately.
+
+ else
+ declare
+ Result_Id : constant Entity_Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('R'));
+ Result_Exp : constant Node_Id :=
+ New_Reference_To (Result_Id, Loc);
+ Result_Obj : constant Node_Id :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Result_Id,
+ Object_Definition =>
+ New_Reference_To (R_Type, Loc),
+ Constant_Present => True,
+ Expression => Relocate_Node (Exp));
+
+ begin
+ Set_Assignment_OK (Result_Obj);
+ Insert_Action (Exp, Result_Obj);
+
+ Rewrite (Exp, Result_Exp);
+ Analyze_And_Resolve (Exp, R_Type);
+ end;
+ end if;
+
+ -- Ada 2005 (AI-344): If the result type is class-wide, then insert
+ -- a check that the level of the return expression's underlying type
+ -- is not deeper than the level of the master enclosing the function.
+ -- Always generate the check when the type of the return expression
+ -- is class-wide, when it's a type conversion, or when it's a formal
+ -- parameter. Otherwise, suppress the check in the case where the
+ -- return expression has a specific type whose level is known not to
+ -- be statically deeper than the function's result type.
+
+ -- Note: accessibility check is skipped in the VM case, since there
+ -- does not seem to be any practical way to implement this check.
+
+ elsif Ada_Version >= Ada_05
+ and then VM_Target = No_VM
+ and then Is_Class_Wide_Type (R_Type)
+ and then not Scope_Suppress (Accessibility_Check)
+ and then
+ (Is_Class_Wide_Type (Etype (Exp))
+ or else Nkind (Exp) = N_Type_Conversion
+ or else Nkind (Exp) = N_Unchecked_Type_Conversion
+ or else (Is_Entity_Name (Exp)
+ and then Ekind (Entity (Exp)) in Formal_Kind)
+ or else Scope_Depth (Enclosing_Dynamic_Scope (Etype (Exp))) >
+ Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))
+ then
+ declare
+ Tag_Node : Node_Id;
+
+ begin
+ -- Ada 2005 (AI-251): In class-wide interface objects we displace
+ -- "this" to reference the base of the object --- required to get
+ -- access to the TSD of the object.
+
+ if Is_Class_Wide_Type (Etype (Exp))
+ and then Is_Interface (Etype (Exp))
+ and then Nkind (Exp) = N_Explicit_Dereference
+ then
+ Tag_Node :=
+ Make_Explicit_Dereference (Loc,
+ Unchecked_Convert_To (RTE (RE_Tag_Ptr),
+ Make_Function_Call (Loc,
+ Name => New_Reference_To (RTE (RE_Base_Address), Loc),
+ Parameter_Associations => New_List (
+ Unchecked_Convert_To (RTE (RE_Address),
+ Duplicate_Subexpr (Prefix (Exp)))))));
+ else
+ Tag_Node :=
+ Make_Attribute_Reference (Loc,
+ Prefix => Duplicate_Subexpr (Exp),
+ Attribute_Name => Name_Tag);
+ end if;
+
+ Insert_Action (Exp,
+ Make_Raise_Program_Error (Loc,
+ Condition =>
+ Make_Op_Gt (Loc,
+ Left_Opnd =>
+ Build_Get_Access_Level (Loc, Tag_Node),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Scope_Depth (Enclosing_Dynamic_Scope (Scope_Id)))),
+ Reason => PE_Accessibility_Check_Failed));
+ end;
+ end if;
+ end Expand_Simple_Function_Return;
------------------------------
-- Make_Tag_Ctrl_Assignment --
Save_Tag : constant Boolean := Is_Tagged_Type (T)
and then not No_Ctrl_Actions (N)
- and then not Java_VM;
- -- Tags are not saved and restored when Java_VM because JVM tags
- -- are represented implicitly in objects.
-
- Res : List_Id;
- Tag_Tmp : Entity_Id;
- Prev_Tmp : Entity_Id;
- Next_Tmp : Entity_Id;
- Ctrl_Ref : Node_Id;
- Ctrl_Ref2 : Node_Id := Empty;
- Prev_Tmp2 : Entity_Id := Empty; -- prevent warning
- Next_Tmp2 : Entity_Id := Empty; -- prevent warning
+ and then VM_Target = No_VM;
+ -- Tags are not saved and restored when VM_Target because VM tags are
+ -- represented implicitly in objects.
+
+ Res : List_Id;
+ Tag_Tmp : Entity_Id;
+
+ Prev_Tmp : Entity_Id;
+ Next_Tmp : Entity_Id;
+ Ctrl_Ref : Node_Id;
begin
Res := New_List;
if not Ctrl_Act then
null;
- -- The left hand side is an uninitialized temporary
+ -- The left hand side is an uninitialized temporary
elsif Nkind (L) = N_Type_Conversion
and then Is_Entity_Name (Expression (L))
With_Detach => New_Reference_To (Standard_False, Loc)));
end if;
- Next_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('C'));
-
-- Save the Tag in a local variable Tag_Tmp
if Save_Tag then
Expression =>
Make_Selected_Component (Loc,
Prefix => Duplicate_Subexpr_No_Checks (L),
- Selector_Name => New_Reference_To (Tag_Component (T), Loc))));
+ Selector_Name => New_Reference_To (First_Tag_Component (T),
+ Loc))));
-- Otherwise Tag_Tmp not used
Tag_Tmp := Empty;
end if;
- -- Save the Finalization Pointers in local variables Prev_Tmp and
- -- Next_Tmp. For objects with Has_Controlled_Component set, these
- -- pointers are in the Record_Controller and if it is also
- -- Is_Controlled, we need to save the object pointers as well.
-
if Ctrl_Act then
- Ctrl_Ref := Duplicate_Subexpr_No_Checks (L);
-
- if Has_Controlled_Component (T) then
- Ctrl_Ref :=
- Make_Selected_Component (Loc,
- Prefix => Ctrl_Ref,
- Selector_Name =>
- New_Reference_To (Controller_Component (T), Loc));
-
- if Is_Controlled (T) then
- Ctrl_Ref2 := Duplicate_Subexpr_No_Checks (L);
- end if;
- end if;
-
- Prev_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('B'));
-
- Append_To (Res,
- Make_Object_Declaration (Loc,
- Defining_Identifier => Prev_Tmp,
+ if VM_Target /= No_VM then
- Object_Definition =>
- New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
+ -- Cannot assign part of the object in a VM context, so instead
+ -- fallback to the previous mechanism, even though it is not
+ -- completely correct ???
- Expression =>
- Make_Selected_Component (Loc,
- Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref),
- Selector_Name => Make_Identifier (Loc, Name_Prev))));
-
- Next_Tmp := Make_Defining_Identifier (Loc, New_Internal_Name ('C'));
-
- Append_To (Res,
- Make_Object_Declaration (Loc,
- Defining_Identifier => Next_Tmp,
+ -- Save the Finalization Pointers in local variables Prev_Tmp and
+ -- Next_Tmp. For objects with Has_Controlled_Component set, these
+ -- pointers are in the Record_Controller
- Object_Definition =>
- New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
+ Ctrl_Ref := Duplicate_Subexpr (L);
- Expression =>
- Make_Selected_Component (Loc,
- Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref)),
- Selector_Name => Make_Identifier (Loc, Name_Next))));
+ if Has_Controlled_Component (T) then
+ Ctrl_Ref :=
+ Make_Selected_Component (Loc,
+ Prefix => Ctrl_Ref,
+ Selector_Name =>
+ New_Reference_To (Controller_Component (T), Loc));
+ end if;
- if Present (Ctrl_Ref2) then
- Prev_Tmp2 :=
+ Prev_Tmp :=
Make_Defining_Identifier (Loc, New_Internal_Name ('B'));
Append_To (Res,
Make_Object_Declaration (Loc,
- Defining_Identifier => Prev_Tmp2,
+ Defining_Identifier => Prev_Tmp,
Object_Definition =>
New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
Expression =>
Make_Selected_Component (Loc,
Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref2),
+ Unchecked_Convert_To (RTE (RE_Finalizable), Ctrl_Ref),
Selector_Name => Make_Identifier (Loc, Name_Prev))));
- Next_Tmp2 :=
- Make_Defining_Identifier (Loc, New_Internal_Name ('C'));
+ Next_Tmp :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('C'));
Append_To (Res,
Make_Object_Declaration (Loc,
- Defining_Identifier => Next_Tmp2,
+ Defining_Identifier => Next_Tmp,
- Object_Definition =>
+ Object_Definition =>
New_Reference_To (RTE (RE_Finalizable_Ptr), Loc),
- Expression =>
+ Expression =>
Make_Selected_Component (Loc,
Prefix =>
Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref2)),
+ New_Copy_Tree (Ctrl_Ref)),
Selector_Name => Make_Identifier (Loc, Name_Next))));
- end if;
- -- If not controlled type, then Prev_Tmp and Ctrl_Ref unused
+ -- Do the Assignment
- else
- Prev_Tmp := Empty;
- Ctrl_Ref := Empty;
- end if;
+ Append_To (Res, Relocate_Node (N));
+
+ else
+ -- Regular (non VM) processing for controlled types and types with
+ -- controlled components
+
+ -- Variables of such types contain pointers used to chain them in
+ -- finalization lists, in addition to user data. These pointers
+ -- are specific to each object of the type, not to the value being
+ -- assigned.
+
+ -- Thus they need to be left intact during the assignment. We
+ -- achieve this by constructing a Storage_Array subtype, and by
+ -- overlaying objects of this type on the source and target of the
+ -- assignment. The assignment is then rewritten to assignments of
+ -- slices of these arrays, copying the user data, and leaving the
+ -- pointers untouched.
+
+ Controlled_Actions : declare
+ Prev_Ref : Node_Id;
+ -- A reference to the Prev component of the record controller
+
+ First_After_Root : Node_Id := Empty;
+ -- Index of first byte to be copied (used to skip
+ -- Root_Controlled in controlled objects).
+
+ Last_Before_Hole : Node_Id := Empty;
+ -- Index of last byte to be copied before outermost record
+ -- controller data.
+
+ Hole_Length : Node_Id := Empty;
+ -- Length of record controller data (Prev and Next pointers)
+
+ First_After_Hole : Node_Id := Empty;
+ -- Index of first byte to be copied after outermost record
+ -- controller data.
+
+ Expr, Source_Size : Node_Id;
+ Source_Actual_Subtype : Entity_Id;
+ -- Used for computation of the size of the data to be copied
+
+ Range_Type : Entity_Id;
+ Opaque_Type : Entity_Id;
+
+ function Build_Slice
+ (Rec : Entity_Id;
+ Lo : Node_Id;
+ Hi : Node_Id) return Node_Id;
+ -- Build and return a slice of an array of type S overlaid on
+ -- object Rec, with bounds specified by Lo and Hi. If either
+ -- bound is empty, a default of S'First (respectively S'Last)
+ -- is used.
+
+ -----------------
+ -- Build_Slice --
+ -----------------
+
+ function Build_Slice
+ (Rec : Node_Id;
+ Lo : Node_Id;
+ Hi : Node_Id) return Node_Id
+ is
+ Lo_Bound : Node_Id;
+ Hi_Bound : Node_Id;
+
+ Opaque : constant Node_Id :=
+ Unchecked_Convert_To (Opaque_Type,
+ Make_Attribute_Reference (Loc,
+ Prefix => Rec,
+ Attribute_Name => Name_Address));
+ -- Access value designating an opaque storage array of type
+ -- S overlaid on record Rec.
- -- Do the Assignment
+ begin
+ -- Compute slice bounds using S'First (1) and S'Last as
+ -- default values when not specified by the caller.
+
+ if No (Lo) then
+ Lo_Bound := Make_Integer_Literal (Loc, 1);
+ else
+ Lo_Bound := Lo;
+ end if;
+
+ if No (Hi) then
+ Hi_Bound := Make_Attribute_Reference (Loc,
+ Prefix => New_Occurrence_Of (Range_Type, Loc),
+ Attribute_Name => Name_Last);
+ else
+ Hi_Bound := Hi;
+ end if;
+
+ return Make_Slice (Loc,
+ Prefix =>
+ Opaque,
+ Discrete_Range => Make_Range (Loc,
+ Lo_Bound, Hi_Bound));
+ end Build_Slice;
+
+ -- Start of processing for Controlled_Actions
- Append_To (Res, Relocate_Node (N));
+ begin
+ -- Create a constrained subtype of Storage_Array whose size
+ -- corresponds to the value being assigned.
+
+ -- subtype G is Storage_Offset range
+ -- 1 .. (Expr'Size + Storage_Unit - 1) / Storage_Unit
+
+ Expr := Duplicate_Subexpr_No_Checks (Expression (N));
+
+ if Nkind (Expr) = N_Qualified_Expression then
+ Expr := Expression (Expr);
+ end if;
- -- Restore the Tag
+ Source_Actual_Subtype := Etype (Expr);
+
+ if Has_Discriminants (Source_Actual_Subtype)
+ and then not Is_Constrained (Source_Actual_Subtype)
+ then
+ Append_To (Res,
+ Build_Actual_Subtype (Source_Actual_Subtype, Expr));
+ Source_Actual_Subtype := Defining_Identifier (Last (Res));
+ end if;
+
+ Source_Size :=
+ Make_Op_Add (Loc,
+ Left_Opnd =>
+ Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Occurrence_Of (Source_Actual_Subtype, Loc),
+ Attribute_Name => Name_Size),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Intval => System_Storage_Unit - 1));
+
+ Source_Size :=
+ Make_Op_Divide (Loc,
+ Left_Opnd => Source_Size,
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Intval => System_Storage_Unit));
+
+ Range_Type :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('G'));
+
+ Append_To (Res,
+ Make_Subtype_Declaration (Loc,
+ Defining_Identifier => Range_Type,
+ Subtype_Indication =>
+ Make_Subtype_Indication (Loc,
+ Subtype_Mark =>
+ New_Reference_To (RTE (RE_Storage_Offset), Loc),
+ Constraint => Make_Range_Constraint (Loc,
+ Range_Expression =>
+ Make_Range (Loc,
+ Low_Bound => Make_Integer_Literal (Loc, 1),
+ High_Bound => Source_Size)))));
+
+ -- subtype S is Storage_Array (G)
+
+ Append_To (Res,
+ Make_Subtype_Declaration (Loc,
+ Defining_Identifier =>
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('S')),
+ Subtype_Indication =>
+ Make_Subtype_Indication (Loc,
+ Subtype_Mark =>
+ New_Reference_To (RTE (RE_Storage_Array), Loc),
+ Constraint =>
+ Make_Index_Or_Discriminant_Constraint (Loc,
+ Constraints =>
+ New_List (New_Reference_To (Range_Type, Loc))))));
+
+ -- type A is access S
+
+ Opaque_Type :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('A'));
+
+ Append_To (Res,
+ Make_Full_Type_Declaration (Loc,
+ Defining_Identifier => Opaque_Type,
+ Type_Definition =>
+ Make_Access_To_Object_Definition (Loc,
+ Subtype_Indication =>
+ New_Occurrence_Of (
+ Defining_Identifier (Last (Res)), Loc))));
+
+ -- Generate appropriate slice assignments
+
+ First_After_Root := Make_Integer_Literal (Loc, 1);
+
+ -- For the case of a controlled object, skip the
+ -- Root_Controlled part.
+
+ if Is_Controlled (T) then
+ First_After_Root :=
+ Make_Op_Add (Loc,
+ First_After_Root,
+ Make_Op_Divide (Loc,
+ Make_Attribute_Reference (Loc,
+ Prefix =>
+ New_Occurrence_Of (RTE (RE_Root_Controlled), Loc),
+ Attribute_Name => Name_Size),
+ Make_Integer_Literal (Loc, System_Storage_Unit)));
+ end if;
+
+ -- For the case of a record with controlled components, skip
+ -- the Prev and Next components of the record controller.
+ -- These components constitute a 'hole' in the middle of the
+ -- data to be copied.
+
+ if Has_Controlled_Component (T) then
+ Prev_Ref :=
+ Make_Selected_Component (Loc,
+ Prefix =>
+ Make_Selected_Component (Loc,
+ Prefix => Duplicate_Subexpr_No_Checks (L),
+ Selector_Name =>
+ New_Reference_To (Controller_Component (T), Loc)),
+ Selector_Name => Make_Identifier (Loc, Name_Prev));
+
+ -- Last index before hole: determined by position of
+ -- the _Controller.Prev component.
+
+ Last_Before_Hole :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('L'));
+
+ Append_To (Res,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Last_Before_Hole,
+ Object_Definition => New_Occurrence_Of (
+ RTE (RE_Storage_Offset), Loc),
+ Constant_Present => True,
+ Expression => Make_Op_Add (Loc,
+ Make_Attribute_Reference (Loc,
+ Prefix => Prev_Ref,
+ Attribute_Name => Name_Position),
+ Make_Attribute_Reference (Loc,
+ Prefix => New_Copy_Tree (Prefix (Prev_Ref)),
+ Attribute_Name => Name_Position))));
+
+ -- Hole length: size of the Prev and Next components
+
+ Hole_Length :=
+ Make_Op_Multiply (Loc,
+ Left_Opnd => Make_Integer_Literal (Loc, Uint_2),
+ Right_Opnd =>
+ Make_Op_Divide (Loc,
+ Left_Opnd =>
+ Make_Attribute_Reference (Loc,
+ Prefix => New_Copy_Tree (Prev_Ref),
+ Attribute_Name => Name_Size),
+ Right_Opnd =>
+ Make_Integer_Literal (Loc,
+ Intval => System_Storage_Unit)));
+
+ -- First index after hole
+
+ First_After_Hole :=
+ Make_Defining_Identifier (Loc,
+ New_Internal_Name ('F'));
+
+ Append_To (Res,
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => First_After_Hole,
+ Object_Definition => New_Occurrence_Of (
+ RTE (RE_Storage_Offset), Loc),
+ Constant_Present => True,
+ Expression =>
+ Make_Op_Add (Loc,
+ Left_Opnd =>
+ Make_Op_Add (Loc,
+ Left_Opnd =>
+ New_Occurrence_Of (Last_Before_Hole, Loc),
+ Right_Opnd => Hole_Length),
+ Right_Opnd => Make_Integer_Literal (Loc, 1))));
+
+ Last_Before_Hole :=
+ New_Occurrence_Of (Last_Before_Hole, Loc);
+ First_After_Hole :=
+ New_Occurrence_Of (First_After_Hole, Loc);
+ end if;
+
+ -- Assign the first slice (possibly skipping Root_Controlled,
+ -- up to the beginning of the record controller if present,
+ -- up to the end of the object if not).
+
+ Append_To (Res, Make_Assignment_Statement (Loc,
+ Name => Build_Slice (
+ Rec => Duplicate_Subexpr_No_Checks (L),
+ Lo => First_After_Root,
+ Hi => Last_Before_Hole),
+
+ Expression => Build_Slice (
+ Rec => Expression (N),
+ Lo => First_After_Root,
+ Hi => New_Copy_Tree (Last_Before_Hole))));
+
+ if Present (First_After_Hole) then
+
+ -- If a record controller is present, copy the second slice,
+ -- from right after the _Controller.Next component up to the
+ -- end of the object.
+
+ Append_To (Res, Make_Assignment_Statement (Loc,
+ Name => Build_Slice (
+ Rec => Duplicate_Subexpr_No_Checks (L),
+ Lo => First_After_Hole,
+ Hi => Empty),
+ Expression => Build_Slice (
+ Rec => Duplicate_Subexpr_No_Checks (Expression (N)),
+ Lo => New_Copy_Tree (First_After_Hole),
+ Hi => Empty)));
+ end if;
+ end Controlled_Actions;
+ end if;
+
+ else
+ Append_To (Res, Relocate_Node (N));
+ end if;
+
+ -- Restore the tag
if Save_Tag then
Append_To (Res,
Name =>
Make_Selected_Component (Loc,
Prefix => Duplicate_Subexpr_No_Checks (L),
- Selector_Name => New_Reference_To (Tag_Component (T), Loc)),
+ Selector_Name => New_Reference_To (First_Tag_Component (T),
+ Loc)),
Expression => New_Reference_To (Tag_Tmp, Loc)));
end if;
- -- Restore the finalization pointers
-
if Ctrl_Act then
- Append_To (Res,
- Make_Assignment_Statement (Loc,
- Name =>
- Make_Selected_Component (Loc,
- Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref)),
- Selector_Name => Make_Identifier (Loc, Name_Prev)),
- Expression => New_Reference_To (Prev_Tmp, Loc)));
+ if VM_Target /= No_VM then
+ -- Restore the finalization pointers
- Append_To (Res,
- Make_Assignment_Statement (Loc,
- Name =>
- Make_Selected_Component (Loc,
- Prefix =>
- Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref)),
- Selector_Name => Make_Identifier (Loc, Name_Next)),
- Expression => New_Reference_To (Next_Tmp, Loc)));
-
- if Present (Ctrl_Ref2) then
Append_To (Res,
Make_Assignment_Statement (Loc,
Name =>
Make_Selected_Component (Loc,
Prefix =>
Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref2)),
+ New_Copy_Tree (Ctrl_Ref)),
Selector_Name => Make_Identifier (Loc, Name_Prev)),
- Expression => New_Reference_To (Prev_Tmp2, Loc)));
+ Expression => New_Reference_To (Prev_Tmp, Loc)));
Append_To (Res,
Make_Assignment_Statement (Loc,
Make_Selected_Component (Loc,
Prefix =>
Unchecked_Convert_To (RTE (RE_Finalizable),
- New_Copy_Tree (Ctrl_Ref2)),
+ New_Copy_Tree (Ctrl_Ref)),
Selector_Name => Make_Identifier (Loc, Name_Next)),
- Expression => New_Reference_To (Next_Tmp2, Loc)));
+ Expression => New_Reference_To (Next_Tmp, Loc)));
end if;
- end if;
- -- Adjust the target after the assignment when controlled. (not in
- -- the init proc since it is an initialization more than an
- -- assignment)
+ -- Adjust the target after the assignment when controlled (not in the
+ -- init proc since it is an initialization more than an assignment).
- if Ctrl_Act then
Append_List_To (Res,
Make_Adjust_Call (
Ref => Duplicate_Subexpr_Move_Checks (L),
return Res;
exception
+ -- Could use comment here ???
+
when RE_Not_Available =>
return Empty_List;
end Make_Tag_Ctrl_Assignment;
- ------------------------------------
- -- Possible_Bit_Aligned_Component --
- ------------------------------------
-
- function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean is
- begin
- case Nkind (N) is
-
- -- Case of indexed component
-
- when N_Indexed_Component =>
- declare
- P : constant Node_Id := Prefix (N);
- Ptyp : constant Entity_Id := Etype (P);
-
- begin
- -- If we know the component size and it is less than 64, then
- -- we are definitely OK. The back end always does assignment
- -- of misaligned small objects correctly.
-
- if Known_Static_Component_Size (Ptyp)
- and then Component_Size (Ptyp) <= 64
- then
- return False;
-
- -- Otherwise, we need to test the prefix, to see if we are
- -- indexing from a possibly unaligned component.
-
- else
- return Possible_Bit_Aligned_Component (P);
- end if;
- end;
-
- -- Case of selected component
-
- when N_Selected_Component =>
- declare
- P : constant Node_Id := Prefix (N);
- Comp : constant Entity_Id := Entity (Selector_Name (N));
-
- begin
- -- If there is no component clause, then we are in the clear
- -- since the back end will never misalign a large component
- -- unless it is forced to do so. In the clear means we need
- -- only the recursive test on the prefix.
-
- if Component_May_Be_Bit_Aligned (Comp) then
- return True;
- else
- return Possible_Bit_Aligned_Component (P);
- end if;
- end;
-
- -- If we have neither a record nor array component, it means that
- -- we have fallen off the top testing prefixes recursively, and
- -- we now have a stand alone object, where we don't have a problem
-
- when others =>
- return False;
-
- end case;
- end Possible_Bit_Aligned_Component;
-
end Exp_Ch5;
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