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Re: [PATCH] Fix PR rtl-optimization/25654 (P1 4.0/4.1/4.2 Regression)
On Mon, 16 Jan 2006, Richard Guenther wrote:
> On Mon, 16 Jan 2006, Richard Guenther wrote:
>
> > This patch fixes the stack slot sharing aliasing problem by making sure
> > to add conflicts for unions of the same type.
> >
> > Bootstrapped and regtested on x86_64-unknown-linux-gnu.
> >
> > Ok for mainline and branches?
And Steven noticed we should avoid adding to the quadraticness there.
The following patch improves this. One could further improve it by
caching the value of aggregate_contains_union_type by type using two
pointer-sets or a hashtable or a sbitmap over the TYPE_UID, but I
doubt the overhead will pay off.
Bootstrapped and regtested on x86_64-unknown-linux-gnu.
Ok for mainline and branches?
Thanks,
Richard.
2006-01-17 Steven Bosscher <stevenb.gcc@gmail.com>
Jan Hubicka <jh@suse.cz>
Richard Guenther <rguenther@suse.de>
PR rtl-optimization/25654
* cfgexpand.c (aggregate_contains_union_type): New function.
(add_alias_set_conflicts): Call it. Make sure to add conflicts
for structure variables of the same type that contain a union type.
* gcc.dg/torture/pr25654.c: New testcase.
* gcc.target/i386/pr25654-3.c: Likewise.
Index: cfgexpand.c
===================================================================
*** cfgexpand.c (revision 109816)
--- cfgexpand.c (working copy)
*************** stack_var_conflict_p (size_t x, size_t y
*** 272,282 ****
gcc_assert (index < stack_vars_conflict_alloc);
return stack_vars_conflict[index];
}
!
/* A subroutine of expand_used_vars. If two variables X and Y have alias
sets that do not conflict, then do add a conflict for these variables
! in the interference graph. We also have to mind MEM_IN_STRUCT_P and
! MEM_SCALAR_P. */
static void
add_alias_set_conflicts (void)
--- 272,306 ----
gcc_assert (index < stack_vars_conflict_alloc);
return stack_vars_conflict[index];
}
!
! /* Returns true if TYPE is or contains a union type. */
!
! static bool
! aggregate_contains_union_type (tree type)
! {
! tree field;
!
! if (TREE_CODE (type) == UNION_TYPE
! || TREE_CODE (type) == QUAL_UNION_TYPE)
! return true;
! if (TREE_CODE (type) == ARRAY_TYPE)
! return aggregate_contains_union_type (TREE_TYPE (type));
! if (TREE_CODE (type) != RECORD_TYPE)
! return false;
!
! for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
! if (TREE_CODE (field) == FIELD_DECL)
! if (aggregate_contains_union_type (TREE_TYPE (field)))
! return true;
!
! return false;
! }
!
/* A subroutine of expand_used_vars. If two variables X and Y have alias
sets that do not conflict, then do add a conflict for these variables
! in the interference graph. We also need to make sure to add conflicts
! for union containing structures of the same type. We also have to mind
! MEM_IN_STRUCT_P and MEM_SCALAR_P. */
static void
add_alias_set_conflicts (void)
*************** add_alias_set_conflicts (void)
*** 287,298 ****
{
tree type_i = TREE_TYPE (stack_vars[i].decl);
bool aggr_i = AGGREGATE_TYPE_P (type_i);
for (j = 0; j < i; ++j)
{
tree type_j = TREE_TYPE (stack_vars[j].decl);
bool aggr_j = AGGREGATE_TYPE_P (type_j);
! if (aggr_i != aggr_j || !objects_must_conflict_p (type_i, type_j))
add_stack_var_conflict (i, j);
}
}
--- 311,327 ----
{
tree type_i = TREE_TYPE (stack_vars[i].decl);
bool aggr_i = AGGREGATE_TYPE_P (type_i);
+ bool contains_union;
+ contains_union = aggregate_contains_union_type (type_i);
for (j = 0; j < i; ++j)
{
tree type_j = TREE_TYPE (stack_vars[j].decl);
bool aggr_j = AGGREGATE_TYPE_P (type_j);
! if (aggr_i != aggr_j
! || !objects_must_conflict_p (type_i, type_j)
! || (contains_union
! && type_i == type_j))
add_stack_var_conflict (i, j);
}
}
Index: testsuite/gcc.dg/torture/pr25654.c
===================================================================
*** testsuite/gcc.dg/torture/pr25654.c (revision 0)
--- testsuite/gcc.dg/torture/pr25654.c (revision 0)
***************
*** 0 ****
--- 1,37 ----
+ /* { dg-do run } */
+
+ extern void abort (void) __attribute__((noreturn));
+
+ union setconflict
+ {
+ short a[20];
+ int b[10];
+ };
+
+ int
+ main ()
+ {
+ int sum = 0;
+ {
+ union setconflict a;
+ short *c;
+ c = a.a;
+ asm ("": "=r" (c):"0" (c));
+ *c = 0;
+ asm ("": "=r" (c):"0" (c));
+ sum += *c;
+ }
+ {
+ union setconflict a;
+ int *c;
+ c = a.b;
+ asm ("": "=r" (c):"0" (c));
+ *c = 1;
+ asm ("": "=r" (c):"0" (c));
+ sum += *c;
+ }
+
+ if (sum != 1)
+ abort();
+ return 0;
+ }
Index: testsuite/gcc.target/i386/pr25654-3.c
===================================================================
*** testsuite/gcc.target/i386/pr25654-3.c (revision 0)
--- testsuite/gcc.target/i386/pr25654-3.c (revision 0)
***************
*** 0 ****
--- 1,41 ----
+ /* { dg-do run } */
+ /* { dg-options "-O2 -mpreferred-stack-boundary=2 -march=i686 -frename-registers" } */
+
+ extern void abort (void) __attribute__((noreturn));
+
+ struct wrapper {
+ union setconflict
+ {
+ short a[20];
+ int b[10];
+ } a;
+ };
+
+ int
+ main ()
+ {
+ int sum = 0;
+ {
+ struct wrapper a;
+ short *c;
+ c = a.a.a;
+ asm ("": "=r" (c):"0" (c));
+ *c = 0;
+ asm ("": "=r" (c):"0" (c));
+ sum += *c;
+ }
+ {
+ struct wrapper a;
+ int *c;
+ c = a.a.b;
+ asm ("": "=r" (c):"0" (c));
+ *c = 1;
+ asm ("": "=r" (c):"0" (c));
+ sum += *c;
+ }
+
+ if (sum != 1)
+ abort();
+ return 0;
+ }
+