[Ada] Fix wrong access to large bit-packed arrays with reverse SSO
2020-06-11 Eric Botcazou <ebotcazou@adacore.com>
gcc/ada/
* exp_pakd.ads: Add paragraph about scalar storage order.
* exp_pakd.adb (Install_PAT): Do not set the scalar storage
order of the PAT here but...
(Set_PB_Type): ...here instead and...
(Create_Packed_Array_Impl_Type): ...here as well.
* rtsfind.ads (RE_Id): Add RE_Rev_Packed_Bytes{1,2,4}.
(RE_Unit_Table): Likewise.
* libgnat/s-unstyp.ads (Rev_Packed_Bytes1): New derived type.
(Rev_Packed_Bytes2): Likewise.
(Rev_Packed_Bytes4): Likewise.
This commit is contained in:
Eric Botcazou
Pierre-Marie de Rodat
parent
cf0a011c2b
commit
adffc36723
@ -501,8 +501,9 @@ package body Exp_Pakd is
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-- packed array type. It creates the type and installs it as required.
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procedure Set_PB_Type;
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-- Sets PB_Type to Packed_Bytes{1,2,4} as required by the alignment
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-- requirements (see documentation in the spec of this package).
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-- Set PB_Type to [Rev_]Packed_Bytes{1,2,4} as required by the alignment
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-- and the scalar storage order requirements (see documentation in the
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-- spec of this package).
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-----------------
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-- Install_PAT --
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@ -580,14 +581,6 @@ package body Exp_Pakd is
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Set_Is_Volatile_Full_Access (PAT, Is_Volatile_Full_Access (Typ));
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Set_Treat_As_Volatile (PAT, Treat_As_Volatile (Typ));
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-- For a non-bit-packed array, propagate reverse storage order
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-- flag from original base type to packed array base type.
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if not Is_Bit_Packed_Array (Typ) then
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Set_Reverse_Storage_Order
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(Etype (PAT), Reverse_Storage_Order (Base_Type (Typ)));
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end if;
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-- We definitely do not want to delay freezing for packed array
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-- types. This is of particular importance for the itypes that are
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-- generated for record components depending on discriminants where
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@ -616,16 +609,36 @@ package body Exp_Pakd is
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or else Alignment (Typ) = 1
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or else Component_Alignment (Typ) = Calign_Storage_Unit
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then
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if Reverse_Storage_Order (Typ) then
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PB_Type := RTE (RE_Rev_Packed_Bytes1);
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else
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PB_Type := RTE (RE_Packed_Bytes1);
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end if;
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elsif Csize mod 4 /= 0
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or else Alignment (Typ) = 2
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then
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if Reverse_Storage_Order (Typ) then
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PB_Type := RTE (RE_Rev_Packed_Bytes2);
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else
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PB_Type := RTE (RE_Packed_Bytes2);
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end if;
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else
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if Reverse_Storage_Order (Typ) then
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PB_Type := RTE (RE_Rev_Packed_Bytes4);
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else
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PB_Type := RTE (RE_Packed_Bytes4);
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end if;
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end if;
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-- The Rev_Packed_Bytes{1,2,4} types cannot be directly declared with
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-- the reverse scalar storage order in System.Unsigned_Types because
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-- their component type is aliased and the combination would then be
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-- flagged as illegal by the compiler. Moreover changing the compiler
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-- would not address the bootstrap path issue with earlier versions.
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Set_Reverse_Storage_Order (PB_Type, Reverse_Storage_Order (Typ));
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end Set_PB_Type;
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-- Start of processing for Create_Packed_Array_Impl_Type
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@ -797,6 +810,10 @@ package body Exp_Pakd is
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end;
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Install_PAT;
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-- Propagate the reverse storage order flag to the base type
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Set_Reverse_Storage_Order (Etype (PAT), Reverse_Storage_Order (Typ));
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return;
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-- Case of bit-packing required for unconstrained array. We create
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@ -86,6 +86,15 @@ package Exp_Pakd is
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-- Packed_Bytes{1,2,4} type is made on the basis of alignment needs as
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-- described above for the unconstrained case.
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-- When the packed array (sub)type is specified to have the reverse scalar
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-- storage order, the Packed_Bytes{1,2,4} references above are replaced
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-- with Rev_Packed_Bytes{1,2,4}. This is necessary because, although the
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-- component type is Packed_Byte and therefore endian neutral, the scalar
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-- storage order of the new type must be compatible with that of an outer
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-- composite type, if this composite type contains a component whose type
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-- is the packed array (sub)type and which does not start or does not end
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-- on a storage unit boundary.
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-- When a variable of packed array type is allocated, gigi will allocate
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-- the amount of space indicated by the corresponding packed array type.
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-- However, we do NOT attempt to rewrite the types of any references or
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@ -51,8 +51,8 @@ package System.Unsigned_Types is
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-- Used in the implementation of Is_Negative intrinsic (see Exp_Intr)
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type Packed_Byte is mod 2 ** 8;
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pragma Universal_Aliasing (Packed_Byte);
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for Packed_Byte'Size use 8;
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pragma Universal_Aliasing (Packed_Byte);
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-- Component type for Packed_Bytes1, Packed_Bytes2 and Packed_Byte4 arrays.
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-- As this type is used by the compiler to implement operations on user
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-- packed array, it needs to be able to alias any type.
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@ -89,6 +89,24 @@ package System.Unsigned_Types is
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-- cases the clusters can be assumed to be 4-byte aligned if the array
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-- is aligned (see System.Pack_12 in file s-pack12 as an example).
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type Rev_Packed_Bytes1 is new Packed_Bytes1;
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pragma Suppress_Initialization (Rev_Packed_Bytes1);
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-- This is equivalent to Packed_Bytes1, but for packed arrays with reverse
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-- scalar storage order. But the Scalar_Storage_Order attribute cannot be
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-- set directly here, see Exp_Pakd for more details.
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type Rev_Packed_Bytes2 is new Packed_Bytes2;
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pragma Suppress_Initialization (Rev_Packed_Bytes2);
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-- This is equivalent to Packed_Bytes2, but for packed arrays with reverse
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-- scalar storage order. But the Scalar_Storage_Order attribute cannot be
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-- set directly here, see Exp_Pakd for more details.
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type Rev_Packed_Bytes4 is new Packed_Bytes4;
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pragma Suppress_Initialization (Rev_Packed_Bytes4);
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-- This is equivalent to Packed_Bytes4, but for packed arrays with reverse
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-- scalar storage order. But the Scalar_Storage_Order attribute cannot be
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-- set directly here, see Exp_Pakd for more details.
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type Bits_1 is mod 2**1;
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type Bits_2 is mod 2**2;
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type Bits_4 is mod 2**4;
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@ -1524,6 +1524,9 @@ package Rtsfind is
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RE_Packed_Bytes1, -- System.Unsigned_Types
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RE_Packed_Bytes2, -- System.Unsigned_Types
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RE_Packed_Bytes4, -- System.Unsigned_Types
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RE_Rev_Packed_Bytes1, -- System.Unsigned_Types
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RE_Rev_Packed_Bytes2, -- System.Unsigned_Types
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RE_Rev_Packed_Bytes4, -- System.Unsigned_Types
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RE_Short_Unsigned, -- System.Unsigned_Types
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RE_Short_Short_Unsigned, -- System.Unsigned_Types
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RE_Unsigned, -- System.Unsigned_Types
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@ -2798,6 +2801,9 @@ package Rtsfind is
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RE_Packed_Bytes1 => System_Unsigned_Types,
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RE_Packed_Bytes2 => System_Unsigned_Types,
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RE_Packed_Bytes4 => System_Unsigned_Types,
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RE_Rev_Packed_Bytes1 => System_Unsigned_Types,
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RE_Rev_Packed_Bytes2 => System_Unsigned_Types,
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RE_Rev_Packed_Bytes4 => System_Unsigned_Types,
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RE_Short_Unsigned => System_Unsigned_Types,
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RE_Short_Short_Unsigned => System_Unsigned_Types,
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RE_Unsigned => System_Unsigned_Types,
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