This attribute returns the alignment honored by malloc.
The following program should display this value:
with Ada.Text_IO; use Ada.Text_IO;
procedure Alloc_Algn is
begin
Put_Line ("malloc alignment:"
& Integer'Image (Standard'System_Allocator_Alignment));
end Alloc_Algn;
Tested on x86_64-pc-linux-gnu, committed on trunk
2011-08-29 Tristan Gingold <ging...@adacore.com>
* sem_attr.adb, exp_attr.adb: Add handling of
Attribute_System_Allocator_Alignment
* snames.ads-tmpl: Add Name_System_Allocator_Alignment and
Attribute_System_Allocator_Alignment.
* ttypes.ads, get_targ.ads: Add Get_System_Allocator_Alignment.
* gcc-interface/targtyps.c, gcc-interface/utils2.c,
gcc-interface/gigi.h: Renames get_target_default_allocator_alignment to
get_target_system_allocator_alignment.
Index: gnat_rm.texi
===================================================================
--- gnat_rm.texi (revision 178168)
+++ gnat_rm.texi (working copy)
@@ -270,6 +270,7 @@
* Small::
* Storage_Unit::
* Stub_Type::
+* System_Allocator_Alignment::
* Target_Name::
* Tick::
* To_Address::
@@ -5752,6 +5753,7 @@
* Small::
* Storage_Unit::
* Stub_Type::
+* System_Allocator_Alignment::
* Target_Name::
* Tick::
* To_Address::
@@ -6490,6 +6492,18 @@
unit @code{System.Partition_Interface}. Use of this attribute will create
an implicit dependency on this unit.
+@node System_Allocator_Alignment
+@unnumberedsec System_Allocator_Alignment
+@cindex Alignment, allocator
+@findex System_Allocator_Alignment
+@noindent
+@code{Standard'System_Allocator_Alignment} (@code{Standard} is the only
+permissible prefix) provides the observable guaranted to be honored by
+the system allocator (malloc). This is a static value that can be used
+in user storage pools based on malloc either to reject allocation
+with alignment too large or to enable a realignment circuitry if the
+alignment request is larger than this value.
+
@node Target_Name
@unnumberedsec Target_Name
@findex Target_Name
Index: exp_attr.adb
===================================================================
--- exp_attr.adb (revision 178166)
+++ exp_attr.adb (working copy)
@@ -5379,6 +5379,7 @@
Attribute_Small |
Attribute_Storage_Unit |
Attribute_Stub_Type |
+ Attribute_System_Allocator_Alignment |
Attribute_Target_Name |
Attribute_Type_Class |
Attribute_Type_Key |
Index: sem_attr.adb
===================================================================
--- sem_attr.adb (revision 178166)
+++ sem_attr.adb (working copy)
@@ -4563,6 +4563,13 @@
end if;
end if;
+ --------------------------------
+ -- System_Allocator_Alignment --
+ --------------------------------
+
+ when Attribute_System_Allocator_Alignment =>
+ Standard_Attribute (Ttypes.System_Allocator_Alignment);
+
---------
-- Tag --
---------
@@ -7698,61 +7705,62 @@
-- Note that in some cases, the values have already been folded as
-- a result of the processing in Analyze_Attribute.
- when Attribute_Abort_Signal |
- Attribute_Access |
- Attribute_Address |
- Attribute_Address_Size |
- Attribute_Asm_Input |
- Attribute_Asm_Output |
- Attribute_Base |
- Attribute_Bit_Order |
- Attribute_Bit_Position |
- Attribute_Callable |
- Attribute_Caller |
- Attribute_Class |
- Attribute_Code_Address |
- Attribute_Compiler_Version |
- Attribute_Count |
- Attribute_Default_Bit_Order |
- Attribute_Elaborated |
- Attribute_Elab_Body |
- Attribute_Elab_Spec |
- Attribute_Elab_Subp_Body |
- Attribute_Enabled |
- Attribute_External_Tag |
- Attribute_Fast_Math |
- Attribute_First_Bit |
- Attribute_Input |
- Attribute_Last_Bit |
- Attribute_Maximum_Alignment |
- Attribute_Old |
- Attribute_Output |
- Attribute_Partition_ID |
- Attribute_Pool_Address |
- Attribute_Position |
- Attribute_Priority |
- Attribute_Read |
- Attribute_Result |
- Attribute_Storage_Pool |
- Attribute_Storage_Size |
- Attribute_Storage_Unit |
- Attribute_Stub_Type |
- Attribute_Tag |
- Attribute_Target_Name |
- Attribute_Terminated |
- Attribute_To_Address |
- Attribute_Type_Key |
- Attribute_UET_Address |
- Attribute_Unchecked_Access |
- Attribute_Universal_Literal_String |
- Attribute_Unrestricted_Access |
- Attribute_Valid |
- Attribute_Value |
- Attribute_Wchar_T_Size |
- Attribute_Wide_Value |
- Attribute_Wide_Wide_Value |
- Attribute_Word_Size |
- Attribute_Write =>
+ when Attribute_Abort_Signal |
+ Attribute_Access |
+ Attribute_Address |
+ Attribute_Address_Size |
+ Attribute_Asm_Input |
+ Attribute_Asm_Output |
+ Attribute_Base |
+ Attribute_Bit_Order |
+ Attribute_Bit_Position |
+ Attribute_Callable |
+ Attribute_Caller |
+ Attribute_Class |
+ Attribute_Code_Address |
+ Attribute_Compiler_Version |
+ Attribute_Count |
+ Attribute_Default_Bit_Order |
+ Attribute_Elaborated |
+ Attribute_Elab_Body |
+ Attribute_Elab_Spec |
+ Attribute_Elab_Subp_Body |
+ Attribute_Enabled |
+ Attribute_External_Tag |
+ Attribute_Fast_Math |
+ Attribute_First_Bit |
+ Attribute_Input |
+ Attribute_Last_Bit |
+ Attribute_Maximum_Alignment |
+ Attribute_Old |
+ Attribute_Output |
+ Attribute_Partition_ID |
+ Attribute_Pool_Address |
+ Attribute_Position |
+ Attribute_Priority |
+ Attribute_Read |
+ Attribute_Result |
+ Attribute_Storage_Pool |
+ Attribute_Storage_Size |
+ Attribute_Storage_Unit |
+ Attribute_Stub_Type |
+ Attribute_System_Allocator_Alignment |
+ Attribute_Tag |
+ Attribute_Target_Name |
+ Attribute_Terminated |
+ Attribute_To_Address |
+ Attribute_Type_Key |
+ Attribute_UET_Address |
+ Attribute_Unchecked_Access |
+ Attribute_Universal_Literal_String |
+ Attribute_Unrestricted_Access |
+ Attribute_Valid |
+ Attribute_Value |
+ Attribute_Wchar_T_Size |
+ Attribute_Wide_Value |
+ Attribute_Wide_Wide_Value |
+ Attribute_Word_Size |
+ Attribute_Write =>
raise Program_Error;
end case;
Index: ttypes.ads
===================================================================
--- ttypes.ads (revision 178155)
+++ ttypes.ads (working copy)
@@ -6,7 +6,7 @@
-- --
-- S p e c --
-- --
--- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2011, 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- --
@@ -188,6 +188,10 @@
-- The maximum alignment, in storage units, that an object or
-- type may require on the target machine.
+ System_Allocator_Alignment : constant Pos :=
+ Get_System_Allocator_Alignment;
+ -- The alignment, in storage units, of addresses returned by malloc.
+
Max_Unaligned_Field : constant Pos := Get_Max_Unaligned_Field;
-- The maximum supported size in bits for a field that is not aligned
-- on a storage unit boundary.
Index: get_targ.ads
===================================================================
--- get_targ.ads (revision 178155)
+++ get_targ.ads (working copy)
@@ -6,7 +6,7 @@
-- --
-- S p e c --
-- --
--- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2011, 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- --
@@ -95,6 +95,10 @@
function Get_Strict_Alignment return Nat;
pragma Import (C, Get_Strict_Alignment, "get_target_strict_alignment");
+ function Get_System_Allocator_Alignment return Nat;
+ pragma Import (C, Get_System_Allocator_Alignment,
+ "get_target_system_allocator_alignment");
+
function Get_Double_Float_Alignment return Nat;
pragma Import (C, Get_Double_Float_Alignment,
"get_target_double_float_alignment");
Index: snames.ads-tmpl
===================================================================
--- snames.ads-tmpl (revision 178165)
+++ snames.ads-tmpl (working copy)
@@ -814,6 +814,7 @@
Name_Storage_Size : constant Name_Id := N + $;
Name_Storage_Unit : constant Name_Id := N + $; -- GNAT
Name_Stream_Size : constant Name_Id := N + $; -- Ada 05
+ Name_System_Allocator_Alignment : constant Name_Id := N + $; -- GNAT
Name_Tag : constant Name_Id := N + $;
Name_Target_Name : constant Name_Id := N + $; -- GNAT
Name_Terminated : constant Name_Id := N + $;
@@ -1354,6 +1355,7 @@
Attribute_Storage_Size,
Attribute_Storage_Unit,
Attribute_Stream_Size,
+ Attribute_System_Allocator_Alignment,
Attribute_Tag,
Attribute_Target_Name,
Attribute_Terminated,
Index: gcc-interface/targtyps.c
===================================================================
--- gcc-interface/targtyps.c (revision 178155)
+++ gcc-interface/targtyps.c (working copy)
@@ -6,7 +6,7 @@
* *
* Body *
* *
- * Copyright (C) 1992-2010, Free Software Foundation, Inc. *
+ * Copyright (C) 1992-2011, 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- *
@@ -149,7 +149,7 @@
return BIGGEST_ALIGNMENT / BITS_PER_UNIT;
}
-/* Standard'Default_Allocator_Alignment. Alignment guaranteed to be honored
+/* Standard'System_Allocator_Alignment. Alignment guaranteed to be honored
by the default allocator (System.Memory.Alloc or malloc if we have no
run-time library at hand).
@@ -172,7 +172,7 @@
#endif
Pos
-get_target_default_allocator_alignment (void)
+get_target_system_allocator_alignment (void)
{
return MALLOC_ALIGNMENT / BITS_PER_UNIT;
}
Index: gcc-interface/utils2.c
===================================================================
--- gcc-interface/utils2.c (revision 178155)
+++ gcc-interface/utils2.c (working copy)
@@ -1907,13 +1907,13 @@
stored just in front. */
unsigned int data_align = TYPE_ALIGN (data_type);
- unsigned int default_allocator_alignment
- = get_target_default_allocator_alignment () * BITS_PER_UNIT;
+ unsigned int system_allocator_alignment
+ = get_target_system_allocator_alignment () * BITS_PER_UNIT;
tree aligning_type
- = ((data_align > default_allocator_alignment)
+ = ((data_align > system_allocator_alignment)
? make_aligning_type (data_type, data_align, data_size,
- default_allocator_alignment,
+ system_allocator_alignment,
POINTER_SIZE / BITS_PER_UNIT)
: NULL_TREE);
@@ -1986,12 +1986,12 @@
return value, stored in front of the data block at allocation time. */
unsigned int data_align = TYPE_ALIGN (data_type);
- unsigned int default_allocator_alignment
- = get_target_default_allocator_alignment () * BITS_PER_UNIT;
+ unsigned int system_allocator_alignment
+ = get_target_system_allocator_alignment () * BITS_PER_UNIT;
tree free_ptr;
- if (data_align > default_allocator_alignment)
+ if (data_align > system_allocator_alignment)
{
/* DATA_FRONT_PTR (void *)
= (void *)DATA_PTR - (void *)sizeof (void *)) */
Index: gcc-interface/gigi.h
===================================================================
--- gcc-interface/gigi.h (revision 178155)
+++ gcc-interface/gigi.h (working copy)
@@ -954,7 +954,7 @@
extern Pos get_target_long_double_size (void);
extern Pos get_target_pointer_size (void);
extern Pos get_target_maximum_default_alignment (void);
-extern Pos get_target_default_allocator_alignment (void);
+extern Pos get_target_system_allocator_alignment (void);
extern Pos get_target_maximum_allowed_alignment (void);
extern Pos get_target_maximum_alignment (void);
extern Nat get_float_words_be (void);
