diff options
Diffstat (limited to 'gcc/ada/layout.adb')
| -rw-r--r-- | gcc/ada/layout.adb | 631 |
1 files changed, 494 insertions, 137 deletions
diff --git a/gcc/ada/layout.adb b/gcc/ada/layout.adb index 0128bf267d3..df310323931 100644 --- a/gcc/ada/layout.adb +++ b/gcc/ada/layout.adb @@ -6,7 +6,7 @@ -- -- -- B o d y -- -- -- --- Copyright (C) 2001-2002 Free Software Foundation, Inc. -- +-- Copyright (C) 2001-2003 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- -- @@ -33,6 +33,7 @@ with Exp_Ch3; use Exp_Ch3; with Exp_Util; use Exp_Util; with Nlists; use Nlists; with Nmake; use Nmake; +with Opt; use Opt; with Repinfo; use Repinfo; with Sem; use Sem; with Sem_Ch13; use Sem_Ch13; @@ -101,6 +102,13 @@ package body Layout is -- knowing that associative rearrangement is allowed for constant -- folding if one of the operands is a compile time known value + function Bits_To_SU (N : Node_Id) return Node_Id; + -- This is used when we cross the boundary from static sizes in bits to + -- dynamic sizes in storage units. If the argument N is anything other + -- than an integer literal, it is returned unchanged, but if it is an + -- integer literal, then it is taken as a size in bits, and is replaced + -- by the corresponding size in bytes. + function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id; -- Given expressions for the low bound (Lo) and the high bound (Hi), -- Build an expression for the value hi-lo+1, converted to type @@ -110,32 +118,41 @@ package body Layout is function Expr_From_SO_Ref (Loc : Source_Ptr; - D : SO_Ref) + D : SO_Ref; + Comp : Entity_Id := Empty) return Node_Id; -- Given a value D from a size or offset field, return an expression -- representing the value stored. If the value is known at compile time, -- then an N_Integer_Literal is returned with the appropriate value. If -- the value references a constant entity, then an N_Identifier node - -- referencing this entity is returned. The Loc value is used for the - -- Sloc value of constructed notes. + -- referencing this entity is returned. If the value denotes a size + -- function, then returns a call node denoting the given function, with + -- a single actual parameter that either refers to the parameter V of + -- an enclosing size function (if Comp is Empty or its type doesn't match + -- the function's formal), or else is a selected component V.c when Comp + -- denotes a component c whose type matches that of the function formal. + -- The Loc value is used for the Sloc value of constructed notes. function SO_Ref_From_Expr (Expr : Node_Id; Ins_Type : Entity_Id; - Vtype : Entity_Id := Empty) + Vtype : Entity_Id := Empty; + Make_Func : Boolean := False) return Dynamic_SO_Ref; -- This routine is used in the case where a size/offset value is dynamic -- and is represented by the expression Expr. SO_Ref_From_Expr checks if -- the Expr contains a reference to the identifier V, and if so builds -- a function depending on discriminants of the formal parameter V which - -- is of type Vtype. If not, then a constant entity with the value Expr - -- is built. The result is a Dynamic_SO_Ref to the created entity. Note - -- that Vtype can be omitted if Expr does not contain any reference to V. - -- the created entity. The declaration created is inserted in the freeze - -- actions of Ins_Type, which also supplies the Sloc for created nodes. - -- This function also takes care of making sure that the expression is - -- properly analyzed and resolved (which may not be the case yet if we - -- build the expression in this unit). + -- is of type Vtype. Otherwise, if the parameter Make_Func is True, then + -- Expr will be encapsulated in a parameterless function; if Make_Func is + -- False, then a constant entity with the value Expr is built. The result + -- is a Dynamic_SO_Ref to the created entity. Note that Vtype can be + -- omitted if Expr does not contain any reference to V, the created entity. + -- The declaration created is inserted in the freeze actions of Ins_Type, + -- which also supplies the Sloc for created nodes. This function also takes + -- care of making sure that the expression is properly analyzed and + -- resolved (which may not be the case yet if we build the expression + -- in this unit). function Get_Max_Size (E : Entity_Id) return Node_Id; -- E is an array type or subtype that has at least one index bound that @@ -143,14 +160,13 @@ package body Layout is -- computes an expression that yields the maximum possible size of the -- array in storage units. The result is not defined for any other type, -- or for arrays that do not depend on discriminants, and it is a fatal - -- error to call this unless Size_Depends_On_Discrminant (E) is True. + -- error to call this unless Size_Depends_On_Discriminant (E) is True. procedure Layout_Array_Type (E : Entity_Id); - -- Front end layout of non-bit-packed array type or subtype + -- Front-end layout of non-bit-packed array type or subtype procedure Layout_Record_Type (E : Entity_Id); - -- Front end layout of record type - -- Variant records not handled yet ??? + -- Front-end layout of record type procedure Rewrite_Integer (N : Node_Id; V : Uint); -- Rewrite node N with an integer literal whose value is V. The Sloc @@ -496,17 +512,67 @@ package body Layout is return Make_Op_Subtract (Loc, Left_Opnd, Right_Opnd); end Assoc_Subtract; + ---------------- + -- Bits_To_SU -- + ---------------- + + function Bits_To_SU (N : Node_Id) return Node_Id is + begin + if Nkind (N) = N_Integer_Literal then + Set_Intval (N, (Intval (N) + (SSU - 1)) / SSU); + end if; + + return N; + end Bits_To_SU; + -------------------- -- Compute_Length -- -------------------- function Compute_Length (Lo : Node_Id; Hi : Node_Id) return Node_Id is - Loc : constant Source_Ptr := Sloc (Lo); - Typ : constant Entity_Id := Etype (Lo); - Lo_Op : Node_Id; - Hi_Op : Node_Id; + Loc : constant Source_Ptr := Sloc (Lo); + Typ : constant Entity_Id := Etype (Lo); + Lo_Op : Node_Id; + Hi_Op : Node_Id; + Lo_Dim : Uint; + Hi_Dim : Uint; begin + -- If the bounds are First and Last attributes for the same dimension + -- and both have prefixes that denotes the same entity, then we create + -- and return a Length attribute. This may allow the back end to + -- generate better code in cases where it already has the length. + + if Nkind (Lo) = N_Attribute_Reference + and then Attribute_Name (Lo) = Name_First + and then Nkind (Hi) = N_Attribute_Reference + and then Attribute_Name (Hi) = Name_Last + and then Is_Entity_Name (Prefix (Lo)) + and then Is_Entity_Name (Prefix (Hi)) + and then Entity (Prefix (Lo)) = Entity (Prefix (Hi)) + then + Lo_Dim := Uint_1; + Hi_Dim := Uint_1; + + if Present (First (Expressions (Lo))) then + Lo_Dim := Expr_Value (First (Expressions (Lo))); + end if; + + if Present (First (Expressions (Hi))) then + Hi_Dim := Expr_Value (First (Expressions (Hi))); + end if; + + if Lo_Dim = Hi_Dim then + return + Make_Attribute_Reference (Loc, + Prefix => New_Occurrence_Of + (Entity (Prefix (Lo)), Loc), + Attribute_Name => Name_Length, + Expressions => New_List + (Make_Integer_Literal (Loc, Lo_Dim))); + end if; + end if; + Lo_Op := New_Copy_Tree (Lo); Hi_Op := New_Copy_Tree (Hi); @@ -542,7 +608,8 @@ package body Layout is function Expr_From_SO_Ref (Loc : Source_Ptr; - D : SO_Ref) + D : SO_Ref; + Comp : Entity_Id := Empty) return Node_Id is Ent : Entity_Id; @@ -552,11 +619,29 @@ package body Layout is Ent := Get_Dynamic_SO_Entity (D); if Is_Discrim_SO_Function (Ent) then - return - Make_Function_Call (Loc, - Name => New_Occurrence_Of (Ent, Loc), - Parameter_Associations => New_List ( - Make_Identifier (Loc, Chars => Vname))); + -- If a component is passed in whose type matches the type + -- of the function formal, then select that component from + -- the "V" parameter rather than passing "V" directly. + + if Present (Comp) + and then Base_Type (Etype (Comp)) + = Base_Type (Etype (First_Formal (Ent))) + then + return + Make_Function_Call (Loc, + Name => New_Occurrence_Of (Ent, Loc), + Parameter_Associations => New_List ( + Make_Selected_Component (Loc, + Prefix => Make_Identifier (Loc, Chars => Vname), + Selector_Name => New_Occurrence_Of (Comp, Loc)))); + + else + return + Make_Function_Call (Loc, + Name => New_Occurrence_Of (Ent, Loc), + Parameter_Associations => New_List ( + Make_Identifier (Loc, Chars => Vname))); + end if; else return New_Occurrence_Of (Ent, Loc); @@ -818,13 +903,13 @@ package body Layout is Insert_Typ : Entity_Id; -- This is the type with which any generated constants or functions -- will be associated (i.e. inserted into the freeze actions). This - -- is normally the type being layed out. The exception occurs when + -- is normally the type being laid out. The exception occurs when -- we are laying out Itype's which are local to a record type, and -- whose scope is this record type. Such types do not have freeze -- nodes (because we have no place to put them). ------------------------------------ - -- How An Array Type is Layed Out -- + -- How An Array Type is Laid Out -- ------------------------------------ -- Here is what goes on. We need to multiply the component size of @@ -875,6 +960,16 @@ package body Layout is -- This is set to True if the final result must be converted from -- bits to storage units (rounding up to a storage unit boundary). + Storage_Divisor : Uint := UI_From_Int (SSU); + -- This is the amount that a nonstatic computed size will be divided + -- by to convert it from bits to storage units. This is normally + -- equal to SSU, but can be reduced in the case of packed components + -- that fit evenly into a storage unit. + + Make_Size_Function : Boolean := False; + -- Indicates whether to request that SO_Ref_From_Expr should + -- encapsulate the array size expresion in a function. + procedure Discrimify (N : in out Node_Id); -- If N represents a discriminant, then the Size.Status is set to -- Discrim, and Vtyp is set. The parameter N is replaced with the @@ -934,6 +1029,13 @@ package body Layout is Insert_Typ := E; end if; + -- If the component type is a generic formal type then there's no point + -- in determining a size for the array type. + + if Is_Generic_Type (Ctyp) then + return; + end if; + -- Deal with component size if base type if Ekind (E) = E_Array_Type then @@ -973,6 +1075,14 @@ package body Layout is Indx := First_Index (E); while Present (Indx) loop Ityp := Etype (Indx); + + -- If an index of the array is a generic formal type then there's + -- no point in determining a size for the array type. + + if Is_Generic_Type (Ityp) then + return; + end if; + Lo := Type_Low_Bound (Ityp); Hi := Type_High_Bound (Ityp); @@ -1041,6 +1151,15 @@ package body Layout is (Dynamic, Make_Integer_Literal (Loc, Size.Val / SSU)); SU_Convert_Required := False; + -- If the current value is a factor of the storage unit, + -- then we can use a value of one for the size and reduce + -- the strength of the later division. + + elsif SSU mod Size.Val = 0 then + Storage_Divisor := SSU / Size.Val; + Size := (Dynamic, Make_Integer_Literal (Loc, Uint_1)); + SU_Convert_Required := True; + -- Otherwise, we go ahead and convert the value in bits, -- and set SU_Convert_Required to True to ensure that the -- final value is indeed properly converted. @@ -1058,41 +1177,50 @@ package body Layout is Len := Compute_Length (Lo, Hi); - -- Check possible range of Len + -- If Len isn't a Length attribute, then its range needs to + -- be checked a possible Max with zero needs to be computed. - declare - OK : Boolean; - LLo : Uint; - LHi : Uint; + if Nkind (Len) /= N_Attribute_Reference + or else Attribute_Name (Len) /= Name_Length + then + declare + OK : Boolean; + LLo : Uint; + LHi : Uint; - begin - Set_Parent (Len, E); - Determine_Range (Len, OK, LLo, LHi); + begin + -- Check possible range of Len - Len := Convert_To (Standard_Unsigned, Len); + Set_Parent (Len, E); + Determine_Range (Len, OK, LLo, LHi); - -- If range definitely flat or superflat, result size is zero + Len := Convert_To (Standard_Unsigned, Len); - if OK and then LHi <= 0 then - Set_Esize (E, Uint_0); - Set_RM_Size (E, Uint_0); - return; - end if; + -- If range definitely flat or superflat, + -- result size is zero - -- If we cannot verify that range cannot be super-flat, we - -- need a maximum with zero, since length cannot be negative. + if OK and then LHi <= 0 then + Set_Esize (E, Uint_0); + Set_RM_Size (E, Uint_0); + return; + end if; - if not OK or else LLo < 0 then - Len := - Make_Attribute_Reference (Loc, - Prefix => - New_Occurrence_Of (Standard_Unsigned, Loc), - Attribute_Name => Name_Max, - Expressions => New_List ( - Make_Integer_Literal (Loc, 0), - Len)); - end if; - end; + -- If we cannot verify that range cannot be super-flat, + -- we need a maximum with zero, since length cannot be + -- negative. + + if not OK or else LLo < 0 then + Len := + Make_Attribute_Reference (Loc, + Prefix => + New_Occurrence_Of (Standard_Unsigned, Loc), + Attribute_Name => Name_Max, + Expressions => New_List ( + Make_Integer_Literal (Loc, 0), + Len)); + end if; + end; + end if; -- At this stage, Len has the expression for the length @@ -1120,15 +1248,42 @@ package body Layout is if SU_Convert_Required then - -- The expression required is (Size.Nod + SU - 1) / SU + -- The expression required is: + -- (Size.Nod + Storage_Divisor - 1) / Storage_Divisor Size.Nod := Make_Op_Divide (Loc, Left_Opnd => Make_Op_Add (Loc, Left_Opnd => Size.Nod, - Right_Opnd => Make_Integer_Literal (Loc, SSU - 1)), - Right_Opnd => Make_Integer_Literal (Loc, SSU)); + Right_Opnd => Make_Integer_Literal + (Loc, Storage_Divisor - 1)), + Right_Opnd => Make_Integer_Literal (Loc, Storage_Divisor)); + end if; + + -- If the array entity is not declared at the library level and its + -- not nested within a subprogram that is marked for inlining, then + -- we request that the size expression be encapsulated in a function. + -- Since this expression is not needed in most cases, we prefer not + -- to incur the overhead of the computation on calls to the enclosing + -- subprogram except for subprograms that require the size. + + if not Is_Library_Level_Entity (E) then + Make_Size_Function := True; + + declare + Parent_Subp : Entity_Id := Enclosing_Subprogram (E); + + begin + while Present (Parent_Subp) loop + if Is_Inlined (Parent_Subp) then + Make_Size_Function := False; + exit; + end if; + + Parent_Subp := Enclosing_Subprogram (Parent_Subp); + end loop; + end; end if; -- Now set the dynamic size (the Value_Size is always the same @@ -1138,7 +1293,10 @@ package body Layout is -- The added initialization sets it to Empty now, but is this -- correct? - Set_Esize (E, SO_Ref_From_Expr (Size.Nod, Insert_Typ, Vtyp)); + Set_Esize + (E, + SO_Ref_From_Expr + (Size.Nod, Insert_Typ, Vtyp, Make_Func => Make_Size_Function)); Set_RM_Size (E, Esize (E)); end if; end Layout_Array_Type; @@ -1199,10 +1357,10 @@ package body Layout is Decl : Node_Id; Comp : Entity_Id; - -- Current component being layed out + -- Current component being laid out Prev_Comp : Entity_Id; - -- Previous layed out component + -- Previous laid out component procedure Get_Next_Component_Location (Prev_Comp : Entity_Id; @@ -1229,10 +1387,7 @@ package body Layout is -- Lays out component Comp, given Prev_Comp, the previously laid-out -- component (Prev_Comp = Empty if no components laid out yet). The -- alignment of the record itself is also updated if needed. Both - -- Comp and Prev_Comp can be either components or discriminants. A - -- special case is when Comp is Empty, this is used at the end - -- to determine the size of the entire record. For this special - -- call the resulting offset is placed in Final_Offset. + -- Comp and Prev_Comp can be either components or discriminants. procedure Layout_Components (From : Entity_Id; @@ -1240,25 +1395,25 @@ package body Layout is Esiz : out SO_Ref; RM_Siz : out SO_Ref); -- This procedure lays out the components of the given component list - -- which contains the components starting with From, and ending with To. - -- The Next_Entity chain is used to traverse the components. On entry + -- which contains the components starting with From and ending with To. + -- The Next_Entity chain is used to traverse the components. On entry, -- Prev_Comp is set to the component preceding the list, so that the - -- list is layed out after this component. Prev_Comp is set to Empty if - -- the component list is to be layed out starting at the start of the - -- record. On return, the components are all layed out, and Prev_Comp is - -- set to the last layed out component. On return, Esiz is set to the + -- list is laid out after this component. Prev_Comp is set to Empty if + -- the component list is to be laid out starting at the start of the + -- record. On return, the components are all laid out, and Prev_Comp is + -- set to the last laid out component. On return, Esiz is set to the -- resulting Object_Size value, which is the length of the record up - -- to and including the last layed out entity. For Esiz, the value is + -- to and including the last laid out entity. For Esiz, the value is -- adjusted to match the alignment of the record. RM_Siz is similarly -- set to the resulting Value_Size value, which is the same length, but -- not adjusted to meet the alignment. Note that in the case of variant -- records, Esiz represents the maximum size. procedure Layout_Non_Variant_Record; - -- Procedure called to layout a non-variant record type or subtype + -- Procedure called to lay out a non-variant record type or subtype procedure Layout_Variant_Record; - -- Procedure called to layout a variant record type. Decl is set to the + -- Procedure called to lay out a variant record type. Decl is set to the -- full type declaration for the variant record. --------------------------------- @@ -1315,8 +1470,10 @@ package body Layout is New_Npos := SO_Ref_From_Expr (Assoc_Add (Loc, - Left_Opnd => Expr_From_SO_Ref (Loc, Old_Npos), - Right_Opnd => Expr_From_SO_Ref (Loc, Old_Esiz)), + Left_Opnd => + Expr_From_SO_Ref (Loc, Old_Npos), + Right_Opnd => + Expr_From_SO_Ref (Loc, Old_Esiz, Prev_Comp)), Ins_Type => E, Vtype => E); @@ -1325,7 +1482,7 @@ package body Layout is if Size_Depends_On_Discriminant (Etype (Prev_Comp)) then Old_Maxsz := Get_Max_Size (Etype (Prev_Comp)); else - Old_Maxsz := Expr_From_SO_Ref (Loc, Old_Esiz); + Old_Maxsz := Expr_From_SO_Ref (Loc, Old_Esiz, Prev_Comp); end if; -- Now we can compute the new max position. If the max size @@ -1373,7 +1530,7 @@ package body Layout is -- Bump alignment if stricter than prev - if Align > Alignment (Prev_Comp) then + if Align > Alignment (Etype (Prev_Comp)) then New_Npos := (New_Npos + Align - 1) / Align * Align; end if; @@ -1452,7 +1609,7 @@ package body Layout is -- Check case of type of component has a scope of the record we -- are laying out. When this happens, the type in question is an - -- Itype that has not yet been layed out (that's because such + -- Itype that has not yet been laid out (that's because such -- types do not get frozen in the normal manner, because there -- is no place for the freeze nodes). @@ -1564,20 +1721,35 @@ package body Layout is End_NPMax : SO_Ref; begin - -- Only layout components if there are some to layout! + -- Only lay out components if there are some to lay out! if Present (From) then - -- Layout components with no component clauses + -- Lay out components with no component clauses Comp := From; loop - if (Ekind (Comp) = E_Component - or else Ekind (Comp) = E_Discriminant) - and then No (Component_Clause (Comp)) + if Ekind (Comp) = E_Component + or else Ekind (Comp) = E_Discriminant then - Layout_Component (Comp, Prev_Comp); - Prev_Comp := Comp; + -- The compatibility of component clauses with composite + -- types isn't checked in Sem_Ch13, so we check it here. + + if Present (Component_Clause (Comp)) then + if Is_Composite_Type (Etype (Comp)) + and then Esize (Comp) < RM_Size (Etype (Comp)) + then + Error_Msg_Uint_1 := RM_Size (Etype (Comp)); + Error_Msg_NE + ("size for & too small, minimum allowed is ^", + Component_Clause (Comp), + Comp); + end if; + + else + Layout_Component (Comp, Prev_Comp); + Prev_Comp := Comp; + end if; end if; exit when Comp = To; @@ -1630,7 +1802,7 @@ package body Layout is Esiz := End_NPMax; if Is_Packed (E) - or else Alignment (Prev_Comp) < Align + or else Alignment (Etype (Prev_Comp)) < Align then -- The expression we build is -- (expr + align - 1) / align * align @@ -1731,7 +1903,7 @@ package body Layout is (Clist : Node_Id; Esiz : out SO_Ref; RM_Siz_Expr : out Node_Id); - -- Recursive procedure, called to layout one component list + -- Recursive procedure, called to lay out one component list -- Esiz and RM_Siz_Expr are set to the Object_Size and Value_Size -- values respectively representing the record size up to and -- including the last component in the component list (including @@ -1875,7 +2047,7 @@ package body Layout is -- care of the others case. if No (RM_Siz_Expr) then - RM_Siz_Expr := RM_SizV; + RM_Siz_Expr := Bits_To_SU (RM_SizV); -- Otherwise construct the appropriate test @@ -1905,19 +2077,28 @@ package body Layout is Left_Opnd => Discrim, Right_Opnd => New_Copy (Dchoice)); + -- Generate a call to the discriminant-checking + -- function for the variant. Note that the result + -- has to be complemented since the function returns + -- False when the passed discriminant value matches. + else Dtest := - Make_Function_Call (Loc, - Name => - New_Occurrence_Of - (Dcheck_Function (Var), Loc), - Parameter_Associations => New_List (Discrim)); + Make_Op_Not (Loc, + Right_Opnd => + Make_Function_Call (Loc, + Name => + New_Occurrence_Of + (Dcheck_Function (Var), Loc), + Parameter_Associations => + New_List (Discrim))); end if; RM_Siz_Expr := Make_Conditional_Expression (Loc, Expressions => - New_List (Dtest, RM_SizV, RM_Siz_Expr)); + New_List + (Dtest, Bits_To_SU (RM_SizV), RM_Siz_Expr)); end if; Prev (Var); @@ -1935,7 +2116,7 @@ package body Layout is Build_Discr_Checking_Funcs (Decl); - -- Layout the discriminants + -- Lay out the discriminants Layout_Components (From => Defining_Identifier (First (Dlist)), @@ -1943,8 +2124,8 @@ package body Layout is Esiz => Esiz, RM_Siz => RM_Siz); - -- Layout the main component list (this will make recursive calls - -- to layout all component lists nested within variants). + -- Lay out the main component list (this will make recursive calls + -- to lay out all component lists nested within variants). Layout_Component_List (Component_List (Tdef), Esiz, RM_Siz_Expr); Set_Esize (E, Esiz); @@ -1991,7 +2172,7 @@ package body Layout is -- All other cases else - -- Initialize aligment conservatively to 1. This value will + -- Initialize alignment conservatively to 1. This value will -- be increased as necessary during processing of the record. if Unknown_Alignment (E) then @@ -2000,8 +2181,8 @@ package body Layout is -- Initialize previous component. This is Empty unless there -- are components which have already been laid out by component - -- clauses. If there are such components, we start our layout of - -- the remaining components following the last such component + -- clauses. If there are such components, we start our lay out of + -- the remaining components following the last such component. Prev_Comp := Empty; @@ -2042,6 +2223,7 @@ package body Layout is if Nkind (Decl) = N_Full_Type_Declaration and then Has_Discriminants (E) and then Nkind (Type_Definition (Decl)) = N_Record_Definition + and then Present (Component_List (Type_Definition (Decl))) and then Present (Variant_Part (Component_List (Type_Definition (Decl)))) then @@ -2112,18 +2294,20 @@ package body Layout is Desig := Full_View (Desig); end if; - if (Is_Array_Type (Desig) + if Is_Array_Type (Desig) and then not Is_Constrained (Desig) and then not Has_Completion_In_Body (Desig) - and then not Debug_Flag_6) + and then not Debug_Flag_6 then Init_Size (E, 2 * System_Address_Size); -- Check for bad convention set - if Convention (E) = Convention_C - or else - Convention (E) = Convention_CPP + if Warn_On_Export_Import + and then + (Convention (E) = Convention_C + or else + Convention (E) = Convention_CPP) then Error_Msg_N ("?this access type does not " & @@ -2144,7 +2328,7 @@ package body Layout is -- For discrete types, the RM_Size and Esize must be set -- already, since this is part of the earlier processing - -- and the front end is always required to layout the + -- and the front end is always required to lay out the -- sizes of such types (since they are available as static -- attributes). All we do is to check that this rule is -- indeed obeyed! @@ -2267,35 +2451,114 @@ package body Layout is end if; end if; - -- Layout array and record types if front end layout set + -- Lay out array and record types if front end layout set if Frontend_Layout_On_Target then if Is_Array_Type (E) and then not Is_Bit_Packed_Array (E) then Layout_Array_Type (E); - return; elsif Is_Record_Type (E) then Layout_Record_Type (E); - return; end if; - -- Special remaining processing for record types with a known size - -- of 16, 32, or 64 bits whose alignment is not yet set. For these - -- types, we set a corresponding alignment matching the size if - -- possible, or as large as possible if not. + -- Case of backend layout, we still do a little in the front end - elsif Is_Record_Type (E) and not Debug_Flag_Q then - Set_Composite_Alignment (E); + else + -- Processing for record types - -- For arrays, we only do this processing for arrays that are - -- required to be atomic. Here, we really need to have proper - -- alignment, but for the normal case of non-atomic arrays it - -- seems better to use the component alignment as the default. + if Is_Record_Type (E) then - elsif Is_Array_Type (E) - and then Is_Atomic (E) - and then not Debug_Flag_Q - then - Set_Composite_Alignment (E); + -- Special remaining processing for record types with a known + -- size of 16, 32, or 64 bits whose alignment is not yet set. + -- For these types, we set a corresponding alignment matching + -- the size if possible, or as large as possible if not. + + if Convention (E) = Convention_Ada + and then not Debug_Flag_Q + then + Set_Composite_Alignment (E); + end if; + + -- Procressing for array types + + elsif Is_Array_Type (E) then + + -- For arrays that are required to be atomic, we do the same + -- processing as described above for short records, since we + -- really need to have the alignment set for the whole array. + + if Is_Atomic (E) and then not Debug_Flag_Q then + Set_Composite_Alignment (E); + end if; + + -- For unpacked array types, set an alignment of 1 if we know + -- that the component alignment is not greater than 1. The reason + -- we do this is to avoid unnecessary copying of slices of such + -- arrays when passed to subprogram parameters (see special test + -- in Exp_Ch6.Expand_Actuals). + + if not Is_Packed (E) + and then Unknown_Alignment (E) + then + if Known_Static_Component_Size (E) + and then Component_Size (E) = 1 + then + Set_Alignment (E, Uint_1); + end if; + end if; + end if; + end if; + + -- Final step is to check that Esize and RM_Size are compatible + + if Known_Static_Esize (E) and then Known_Static_RM_Size (E) then + if Esize (E) < RM_Size (E) then + + -- Esize is less than RM_Size. That's not good. First we test + -- whether this was set deliberately with an Object_Size clause + -- and if so, object to the clause. + + if Has_Object_Size_Clause (E) then + Error_Msg_Uint_1 := RM_Size (E); + Error_Msg_F + ("object size is too small, minimum is ^", + Expression (Get_Attribute_Definition_Clause + (E, Attribute_Object_Size))); + end if; + + -- Adjust Esize up to RM_Size value + + declare + Size : constant Uint := RM_Size (E); + + begin + Set_Esize (E, RM_Size (E)); + + -- For scalar types, increase Object_Size to power of 2, + -- but not less than a storage unit in any case (i.e., + -- normally this means it will be byte addressable). + + if Is_Scalar_Type (E) then + if Size <= System_Storage_Unit then + Init_Esize (E, System_Storage_Unit); + elsif Size <= 16 then + Init_Esize (E, 16); + elsif Size <= 32 then + Init_Esize (E, 32); + else + Set_Esize (E, (Size + 63) / 64 * 64); + end if; + + -- Finally, make sure that alignment is consistent with + -- the newly assigned size. + + while Alignment (E) * System_Storage_Unit < Esize (E) + and then Alignment (E) < Maximum_Alignment + loop + Set_Alignment (E, 2 * Alignment (E)); + end loop; + end if; + end; + end if; end if; end Layout_Type; @@ -2433,29 +2696,102 @@ package body Layout is -- Size is known, alignment is not set - if Siz = System_Storage_Unit then - Align := 1; - elsif Siz = 2 * System_Storage_Unit then + -- Reset alignment to match size if size is exactly 2, 4, or 8 bytes + + if Siz = 2 * System_Storage_Unit then Align := 2; elsif Siz = 4 * System_Storage_Unit then Align := 4; elsif Siz = 8 * System_Storage_Unit then Align := 8; + + -- On VMS, also reset for odd "in between" sizes, e.g. a 17-bit + -- record is given an alignment of 4. This is more consistent with + -- what DEC Ada does. + + elsif OpenVMS_On_Target and then Siz > System_Storage_Unit then + + if Siz <= 2 * System_Storage_Unit then + Align := 2; + elsif Siz <= 4 * System_Storage_Unit then + Align := 4; + elsif Siz <= 8 * System_Storage_Unit then + Align := 8; + else + return; + end if; + + -- No special alignment fiddling needed + else return; end if; + -- Here Align is set to the proposed improved alignment + if Align > Maximum_Alignment then Align := Maximum_Alignment; end if; - if Align > System_Word_Size / System_Storage_Unit then - Align := System_Word_Size / System_Storage_Unit; + -- Further processing for record types only to reduce the alignment + -- set by the above processing in some specific cases. We do not + -- do this for atomic records, since we need max alignment there. + + if Is_Record_Type (E) then + + -- For records, there is generally no point in setting alignment + -- higher than word size since we cannot do better than move by + -- words in any case + + if Align > System_Word_Size / System_Storage_Unit then + Align := System_Word_Size / System_Storage_Unit; + end if; + + -- Check components. If any component requires a higher + -- alignment, then we set that higher alignment in any case. + + declare + Comp : Entity_Id; + + begin + Comp := First_Component (E); + while Present (Comp) loop + if Known_Alignment (Etype (Comp)) then + declare + Calign : constant Uint := Alignment (Etype (Comp)); + + begin + -- The cases to worry about are when the alignment + -- of the component type is larger than the alignment + -- we have so far, and either there is no component + -- clause for the alignment, or the length set by + -- the component clause matches the alignment set. + + if Calign > Align + and then + (Unknown_Esize (Comp) + or else (Known_Static_Esize (Comp) + and then + Esize (Comp) = + Calign * System_Storage_Unit)) + then + Align := UI_To_Int (Calign); + end if; + end; + end if; + + Next_Component (Comp); + end loop; + end; end if; + -- Set chosen alignment + Set_Alignment (E, UI_From_Int (Align)); - if Unknown_Esize (E) then + if Known_Static_Esize (E) + and then Esize (E) < Align * System_Storage_Unit + then Set_Esize (E, UI_From_Int (Align * System_Storage_Unit)); end if; end if; @@ -2519,7 +2855,7 @@ package body Layout is return; -- If the size is not set, then don't attempt to set the alignment. This - -- happens in the backend layout case for access to subprogram types. + -- happens in the backend layout case for access-to-subprogram types. elsif not Known_Static_Esize (E) then return; @@ -2576,8 +2912,9 @@ package body Layout is function SO_Ref_From_Expr (Expr : Node_Id; Ins_Type : Entity_Id; - Vtype : Entity_Id := Empty) - return Dynamic_SO_Ref + Vtype : Entity_Id := Empty; + Make_Func : Boolean := False) + return Dynamic_SO_Ref is Loc : constant Source_Ptr := Sloc (Ins_Type); @@ -2653,7 +2990,27 @@ package body Layout is Make_Return_Statement (Loc, Expression => Expr)))); - -- No reference to V, create constant + -- The caller requests that the expression be encapsulated in + -- a parameterless function. + + elsif Make_Func then + Decl := + Make_Subprogram_Body (Loc, + + Specification => + Make_Function_Specification (Loc, + Defining_Unit_Name => K, + Parameter_Specifications => Empty_List, + Subtype_Mark => New_Occurrence_Of (Standard_Unsigned, Loc)), + + Declarations => Empty_List, + + Handled_Statement_Sequence => + Make_Handled_Sequence_Of_Statements (Loc, + Statements => New_List ( + Make_Return_Statement (Loc, Expression => Expr)))); + + -- No reference to V and function not requested, so create a constant else Decl := |