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[patch] Fix LTO warning on types with variable offsets
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 14 May 2010 23:55:06 +0200
- Subject: [patch] Fix LTO warning on types with variable offsets
Hi,
this is exposed by ACATS cc54002. The LTO compiler fails to merge compatible
types when they contain a field with variable (self-referential) offset and
thus issues a warning. Such an offset is meaningless once gimplification is
done because it has been instantiated as operand #2 of the COMPONENT_REF
built for each access, and is therefore reset.
Tested on i586-suse-linux, Ok for mainline?
2010-05-14 Eric Botcazou <ebotcazou@adacore.com>
* gimple.h (compare_field_offset): Rename into...
(gimple_compare_field_offset): ...this.
* gimple.c (compare_field_offset): Rename into...
(gimple_compare_field_offset): ...this. Compare the full access if
the offset is self-referential.
(gimple_types_compatible_p): Adjust for above renaming.
* lto-streamer-in.c (input_gimple_stmt): Likewise. Also compare the
DECL_NONADDRESSABLE_P flag of fields before merging them.
2010-05-14 Eric Botcazou <ebotcazou@adacore.com>
* gnat.dg/lto9.adb: New test.
* gnat.dg/lto9_pkg1.ads: New helper.
* gnat.dg/lto9_pkg2.ad[sb]: Likewise.
--
Eric Botcazou
Index: gimple.h
===================================================================
--- gimple.h (revision 159388)
+++ gimple.h (working copy)
@@ -946,7 +946,7 @@ extern bool is_gimple_call_addr (tree);
extern tree get_call_expr_in (tree t);
extern void recalculate_side_effects (tree);
-extern bool compare_field_offset (tree, tree);
+extern bool gimple_compare_field_offset (tree, tree);
extern tree gimple_register_type (tree);
extern void print_gimple_types_stats (void);
extern void free_gimple_type_tables (void);
Index: gimple.c
===================================================================
--- gimple.c (revision 159388)
+++ gimple.c (working copy)
@@ -3215,16 +3215,35 @@ compare_type_names_p (tree t1, tree t2,
return false;
}
-/* Return true if the field decls F1 and F2 are at the same offset. */
+/* Return true if the field decls F1 and F2 are at the same offset.
+
+ This is intended to be used on GIMPLE types only. In order to
+ compare GENERIC types, use fields_compatible_p instead. */
bool
-compare_field_offset (tree f1, tree f2)
+gimple_compare_field_offset (tree f1, tree f2)
{
if (DECL_OFFSET_ALIGN (f1) == DECL_OFFSET_ALIGN (f2))
- return (operand_equal_p (DECL_FIELD_OFFSET (f1),
- DECL_FIELD_OFFSET (f2), 0)
- && tree_int_cst_equal (DECL_FIELD_BIT_OFFSET (f1),
- DECL_FIELD_BIT_OFFSET (f2)));
+ {
+ tree offset1 = DECL_FIELD_OFFSET (f1);
+ tree offset2 = DECL_FIELD_OFFSET (f2);
+ return ((offset1 == offset2
+ /* Once gimplification is done, self-referential offsets are
+ instantiated as operand #2 of the COMPONENT_REF built for
+ each access and reset. Therefore, they are not relevant
+ anymore and fields are interchangeable provided that they
+ represent the same access. */
+ || (TREE_CODE (offset1) == PLACEHOLDER_EXPR
+ && TREE_CODE (offset2) == PLACEHOLDER_EXPR
+ && (DECL_SIZE (f1) == DECL_SIZE (f2)
+ || (TREE_CODE (DECL_SIZE (f1)) == PLACEHOLDER_EXPR
+ && TREE_CODE (DECL_SIZE (f2)) == PLACEHOLDER_EXPR)
+ || operand_equal_p (DECL_SIZE (f1), DECL_SIZE (f2), 0))
+ && DECL_ALIGN (f1) == DECL_ALIGN (f2))
+ || operand_equal_p (offset1, offset2, 0))
+ && tree_int_cst_equal (DECL_FIELD_BIT_OFFSET (f1),
+ DECL_FIELD_BIT_OFFSET (f2)));
+ }
/* Fortran and C do not always agree on what DECL_OFFSET_ALIGN
should be, so handle differing ones specially by decomposing
@@ -3572,7 +3591,7 @@ gimple_types_compatible_p (tree t1, tree
/* The fields must have the same name, offset and type. */
if (DECL_NAME (f1) != DECL_NAME (f2)
|| DECL_NONADDRESSABLE_P (f1) != DECL_NONADDRESSABLE_P (f2)
- || !compare_field_offset (f1, f2)
+ || !gimple_compare_field_offset (f1, f2)
|| !gimple_types_compatible_p (TREE_TYPE (f1),
TREE_TYPE (f2)))
goto different_types;
Index: lto-streamer-in.c
===================================================================
--- lto-streamer-in.c (revision 159388)
+++ lto-streamer-in.c (working copy)
@@ -1094,7 +1094,9 @@ input_gimple_stmt (struct lto_input_bloc
{
if (tem == field
|| (TREE_TYPE (tem) == TREE_TYPE (field)
- && compare_field_offset (tem, field)))
+ && DECL_NONADDRESSABLE_P (tem)
+ == DECL_NONADDRESSABLE_P (field)
+ && gimple_compare_field_offset (tem, field)))
break;
}
/* In case of type mismatches across units we can fail
-- { dg-do run }
-- { dg-options "-flto" { target lto } }
with Lto9_Pkg1; use Lto9_Pkg1;
procedure Lto9 is
begin
District_Subscription_Lists.Put
(List => District_01_Subscribers,
Elem_Ptr => New_Subscriber_01'Access,
Location => 1);
end;
with Lto9_Pkg2;
package Lto9_Pkg1 is
subtype Lengths is Natural range 0 .. 50;
type Subscriber (NLen, ALen: Lengths := 50) is record
Name : String(1 .. NLen);
Address : String(1 .. ALen);
end record;
type Subscriber_Ptr is access all Subscriber;
package District_Subscription_Lists is new Lto9_Pkg2
(Element_Type => Subscriber,
Element_Ptr => Subscriber_Ptr,
Size => 100);
District_01_Subscribers : District_Subscription_Lists.List_Type;
New_Subscriber_01 : aliased Subscriber :=
(12, 23, "Brown, Silas", "King's Pyland, Dartmoor");
end Lto9_Pkg1;
package body Lto9_Pkg2 is
procedure Put (List : in out List_Type;
Elem_Ptr : in Element_Ptr;
Location : in Index) is
begin
List.Elements(Location) := Elem_Ptr;
end Put;
end Lto9_Pkg2;
generic
Size : in Positive;
type Element_Type (<>) is private;
type Element_Ptr is access all Element_Type;
package Lto9_Pkg2 is
subtype Index is Positive range 1 .. (Size + 1);
type List_Array is array (Index) of Element_Ptr;
type List_Type is record
Elements : List_Array;
end record;
procedure Put (List : in out List_Type;
Elem_Ptr : in Element_Ptr;
Location : in Index);
end Lto9_Pkg2;