... when its length is close to Natural'Last.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* libgnat/a-strunb__shared.ads (Allocate): Additional parameter
to provide additional amount of space to be allocated.
* libgnat/a-strunb__shared.adb (Aligned_Max_Length): Limit
length to Natural'Last when requested length is larger than it.
(Allocate): Merge two slightly different implementations into
one.diff --git a/gcc/ada/libgnat/a-strunb__shared.adb b/gcc/ada/libgnat/a-strunb__shared.adb
--- a/gcc/ada/libgnat/a-strunb__shared.adb
+++ b/gcc/ada/libgnat/a-strunb__shared.adb
@@ -50,11 +50,13 @@ package body Ada.Strings.Unbounded is
-- align the returned memory on the maximum alignment as malloc does not
-- know the target alignment.
- function Aligned_Max_Length (Max_Length : Natural) return Natural;
+ function Aligned_Max_Length
+ (Required_Length : Natural;
+ Reserved_Length : Natural) return Natural;
-- Returns recommended length of the shared string which is greater or
- -- equal to specified length. Calculation take in sense alignment of the
- -- allocated memory segments to use memory effectively by Append/Insert/etc
- -- operations.
+ -- equal to specified required length and desired reserved length.
+ -- Calculation takes into account alignment of the allocated memory
+ -- segments to use memory effectively by Append/Insert/etc operations.
function Sum (Left : Natural; Right : Integer) return Natural with Inline;
-- Returns summary of Left and Right, raise Constraint_Error on overflow
@@ -63,11 +65,6 @@ package body Ada.Strings.Unbounded is
-- Returns multiplication of Left and Right, raise Constraint_Error on
-- overflow
- function Allocate
- (Length, Growth : Natural) return not null Shared_String_Access;
- -- Allocates new Shared_String with at least specified Length plus optional
- -- Growth.
-
---------
-- "&" --
---------
@@ -490,17 +487,24 @@ package body Ada.Strings.Unbounded is
-- Aligned_Max_Length --
------------------------
- function Aligned_Max_Length (Max_Length : Natural) return Natural is
+ function Aligned_Max_Length
+ (Required_Length : Natural;
+ Reserved_Length : Natural) return Natural
+ is
Static_Size : constant Natural :=
Empty_Shared_String'Size / Standard'Storage_Unit;
-- Total size of all Shared_String static components
begin
- if Max_Length > Natural'Last - Static_Size then
+ if Required_Length > Natural'Last - Static_Size - Reserved_Length then
+ -- Total requested length is larger than maximum possible length.
+ -- Use of Static_Size needed to avoid overflows in expression to
+ -- compute aligned length.
return Natural'Last;
+
else
return
- ((Static_Size + Max_Length - 1) / Min_Mul_Alloc + 2) * Min_Mul_Alloc
- - Static_Size;
+ ((Static_Size + Required_Length + Reserved_Length - 1)
+ / Min_Mul_Alloc + 2) * Min_Mul_Alloc - Static_Size;
end if;
end Aligned_Max_Length;
@@ -509,35 +513,21 @@ package body Ada.Strings.Unbounded is
--------------
function Allocate
- (Max_Length : Natural) return not null Shared_String_Access
+ (Required_Length : Natural;
+ Reserved_Length : Natural := 0) return not null Shared_String_Access
is
begin
-- Empty string requested, return shared empty string
- if Max_Length = 0 then
+ if Required_Length = 0 then
return Empty_Shared_String'Access;
-- Otherwise, allocate requested space (and probably some more room)
else
- return new Shared_String (Aligned_Max_Length (Max_Length));
- end if;
- end Allocate;
-
- --------------
- -- Allocate --
- --------------
-
- function Allocate
- (Length, Growth : Natural) return not null Shared_String_Access is
- begin
- if Natural'Last - Growth < Length then
- -- Then Length + Growth would be more than Natural'Last
-
- return new Shared_String (Integer'Last);
-
- else
- return Allocate (Length + Growth);
+ return
+ new Shared_String
+ (Aligned_Max_Length (Required_Length, Reserved_Length));
end if;
end Allocate;
@@ -657,7 +647,7 @@ package body Ada.Strings.Unbounded is
System.Atomic_Counters.Is_One (Item.Counter)
and then Item.Max_Length >= Length
and then Item.Max_Length <=
- Aligned_Max_Length (Length + Length / Growth_Factor);
+ Aligned_Max_Length (Length, Length / Growth_Factor);
end Can_Be_Reused;
-----------
diff --git a/gcc/ada/libgnat/a-strunb__shared.ads b/gcc/ada/libgnat/a-strunb__shared.ads
--- a/gcc/ada/libgnat/a-strunb__shared.ads
+++ b/gcc/ada/libgnat/a-strunb__shared.ads
@@ -725,10 +725,12 @@ private
-- store string with specified length effectively.
function Allocate
- (Max_Length : Natural) return not null Shared_String_Access;
- -- Allocates new Shared_String with at least specified maximum length.
- -- Actual maximum length of the allocated Shared_String can be slightly
- -- greater. Returns reference to Empty_Shared_String when requested length
+ (Required_Length : Natural;
+ Reserved_Length : Natural := 0) return not null Shared_String_Access;
+ -- Allocates new Shared_String. Actual maximum length of allocated object
+ -- is at least the specified required length. Additional storage is
+ -- allocated to allow to store up to the specified reserved length when
+ -- possible. Returns reference to Empty_Shared_String when requested length
-- is zero.
Empty_Shared_String : aliased Shared_String (0);
