diff options
Diffstat (limited to 'gcc/ada/exp_ch5.adb')
| -rw-r--r-- | gcc/ada/exp_ch5.adb | 88 |
1 files changed, 20 insertions, 68 deletions
diff --git a/gcc/ada/exp_ch5.adb b/gcc/ada/exp_ch5.adb index a257b27..7c08b2a 100644 --- a/gcc/ada/exp_ch5.adb +++ b/gcc/ada/exp_ch5.adb @@ -48,6 +48,7 @@ with Sem_Res; use Sem_Res; with Sem_Util; use Sem_Util; with Snames; use Snames; with Stand; use Stand; +with Stringt; use Stringt; with Tbuild; use Tbuild; with Ttypes; use Ttypes; with Uintp; use Uintp; @@ -75,8 +76,7 @@ package body Exp_Ch5 is L_Type : Entity_Id; R_Type : Entity_Id; Ndim : Pos; - Rev : Boolean) - return Node_Id; + Rev : Boolean) return Node_Id; -- N is an assignment statement which assigns an array value. This routine -- expands the assignment into a loop (or nested loops for the case of a -- multi-dimensional array) to do the assignment component by component. @@ -104,32 +104,11 @@ package body Exp_Ch5 is 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 back end can handle such assignments fine - -- if the objects involved are small (64-bits or less) records or - -- scalar items (including bit-packed arrays represented with modular - -- types) or are both aligned on a byte boundary (starting on a byte - -- boundary, and occupying an integral number of bytes). - -- - -- However, problems arise for records larger than 64 bits, or for - -- arrays (other than bit-packed arrays represented with a modular - -- type) if the component starts on a non-byte boundary, or does - -- not occupy an integral number of bytes (i.e. there are some bits - -- possibly shared with fields at the start or beginning of the - -- component). The back end cannot handle loading and storing such - -- components in a single operation. - -- - -- This function is used to detect the troublesome situation. it is - -- conservative in the sense that it produces True unless it knows - -- for sure that the component is safe (as outlined in the first - -- paragraph above). The code generation for record and array - -- assignment checks for trouble using this function, and if so - -- the assignment is generated component-wise, which the back end - -- is required to handle correctly. - -- - -- Note that in GNAT 3, the back end will reject such components - -- anyway, so the hard work in checking for this case is wasted - -- in GNAT 3, but it's harmless, so it is easier to do it in - -- all cases, rather than conditionalize it in GNAT 5 or beyond. + -- 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 Sem_Util.Component_May_Be_Bit_Aligned for further details). ------------------------------ -- Change_Of_Representation -- @@ -508,9 +487,12 @@ package body Exp_Ch5 is -- 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 + elsif Nkind (Rhs) = N_String_Literal then - if Ekind (R_Type) = E_String_Literal_Subtype - and then String_Literal_Length (R_Type) = 0 + if String_Length (Strval (Rhs)) = 0 and then Is_Bit_Packed_Array (L_Type) then Rewrite (N, Make_Null_Statement (Loc)); @@ -731,8 +713,8 @@ package body Exp_Ch5 is elsif Restrictions (No_Implicit_Conditionals) then declare - T : constant Entity_Id := Make_Defining_Identifier (Loc, - Chars => Name_T); + T : constant Entity_Id := + Make_Defining_Identifier (Loc, Chars => Name_T); begin Rewrite (N, @@ -881,8 +863,7 @@ package body Exp_Ch5 is L_Type : Entity_Id; R_Type : Entity_Id; Ndim : Pos; - Rev : Boolean) - return Node_Id + Rev : Boolean) return Node_Id is Loc : constant Source_Ptr := Sloc (N); @@ -2244,8 +2225,8 @@ package body Exp_Ch5 is and then List_Length (Else_Statements (N)) = 1 then declare - Then_Stm : Node_Id := First (Then_Statements (N)); - Else_Stm : Node_Id := First (Else_Statements (N)); + Then_Stm : constant Node_Id := First (Then_Statements (N)); + Else_Stm : constant Node_Id := First (Else_Statements (N)); begin if Nkind (Then_Stm) = N_Return_Statement @@ -3277,39 +3258,10 @@ package body Exp_Ch5 is -- unless it is forced to do so. In the clear means we need -- only the recursive test on the prefix. - if No (Component_Clause (Comp)) then - return Possible_Bit_Aligned_Component (P); - - -- Otherwise we have a component clause, which means that - -- the Esize and Normalized_First_Bit fields are set and - -- contain static values known at compile time. - + if Component_May_Be_Bit_Aligned (Comp) then + return True; else - -- If we know that we have a small (64 bits or less) record - -- or bit-packed array, then everything is fine, since the - -- back end can handle these cases correctly. - - if Esize (Comp) <= 64 - and then (Is_Record_Type (Etype (Comp)) - or else - Is_Bit_Packed_Array (Etype (Comp))) - then - return False; - - -- Otherwise if the component is not byte aligned, we - -- know we have the nasty unaligned case. - - elsif Normalized_First_Bit (Comp) /= Uint_0 - or else Esize (Comp) mod System_Storage_Unit /= Uint_0 - then - return True; - - -- If we are large and byte aligned, then OK at this level - -- but we still need to test our prefix recursively. - - else - return Possible_Bit_Aligned_Component (P); - end if; + return Possible_Bit_Aligned_Component (P); end if; end; |