Hi,
On Thu, Dec 06, 2012 at 10:35:04AM +0100, Richard Guenther wrote:
> Don't you want to use get_object_alignment_1 to record whether
> 'base' is for example at offset 3 of a 16-byte aligned object
> so that if 'offset' then makes the result aligned you use
> that alignment instead of the conservative 1-byte alignment
> you'd otherwise get from get_object_alignment?
>
> That is, how do 'offset' and 'base' relate? As far as I understand
> align should be computed as the alignment of the access to
> 'base' plus offset 'offset', no?
You're right, such situation can occur too, even though probably only
rarely. Below is a patch that uses get_object_alignment_1, it has
passed bootstrap and testing on x86_64-linux, and powerpc64-linux, the
same on sparc64-linux is underway. OK for trunk if it passes there
too?
Thanks,
Martin
2012-12-06 Martin Jambor <mjam...@suse.cz>
PR tree-optimization/55590
* tree-sra.c (build_ref_for_offset): Use get_object_alignment_1 to
get base alignment.
* testsuite/gcc.target/i386/pr55590-1.c: New test.
* testsuite/gcc.target/i386/pr55590-2.c: Likewise.
*** /dev/null Thu Oct 25 13:49:30 2012
--- gcc/testsuite/gcc.target/i386/pr55590-1.c Tue Dec 4 11:36:54 2012
***************
*** 0 ****
--- 1,27 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -mavx" } */
+
+ #include <immintrin.h>
+
+ struct S
+ {
+ __m128 a, b;
+ };
+
+ struct T
+ {
+ int a;
+ struct S s;
+ };
+
+
+ void foo (struct T *p, __m128 v)
+ {
+ struct S s;
+
+ s = p->s;
+ s.b = _mm_add_ps(s.b, v);
+ p->s = s;
+ }
+
+ /* { dg-final { scan-assembler-not "vmovups" } } */
*** /dev/null Thu Oct 25 13:49:30 2012
--- gcc/testsuite/gcc.target/i386/pr55590-2.c Tue Dec 4 11:37:02 2012
***************
*** 0 ****
--- 1,27 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -mavx" } */
+
+ #include <immintrin.h>
+
+ struct S
+ {
+ __m128 a, b;
+ };
+
+ struct T
+ {
+ int a;
+ struct S s[8];
+ };
+
+
+ void foo (struct T *p, int i, __m128 v)
+ {
+ struct S s;
+
+ s = p->s[i];
+ s.b = _mm_add_ps(s.b, v);
+ p->s[i] = s;
+ }
+
+ /* { dg-final { scan-assembler-not "vmovups" } } */
*** /tmp/sOn2fd_tree-sra.c Thu Dec 6 15:49:23 2012
--- gcc/tree-sra.c Thu Dec 6 11:46:23 2012
*************** make_fancy_name (tree expr)
*** 1423,1429 ****
EXP_TYPE at the given OFFSET. If BASE is something for which
get_addr_base_and_unit_offset returns NULL, gsi must be non-NULL and is
used
to insert new statements either before or below the current one as
specified
! by INSERT_AFTER. This function is not capable of handling bitfields. */
tree
build_ref_for_offset (location_t loc, tree base, HOST_WIDE_INT offset,
--- 1423,1432 ----
EXP_TYPE at the given OFFSET. If BASE is something for which
get_addr_base_and_unit_offset returns NULL, gsi must be non-NULL and is
used
to insert new statements either before or below the current one as
specified
! by INSERT_AFTER. This function is not capable of handling bitfields.
!
! BASE must be either a declaration or a memory reference that has correct
! alignment ifformation embeded in it (e.g. a pre-existing one in SRA). */
tree
build_ref_for_offset (location_t loc, tree base, HOST_WIDE_INT offset,
*************** build_ref_for_offset (location_t loc, tr
*** 1437,1443 ****
unsigned int align;
gcc_checking_assert (offset % BITS_PER_UNIT == 0);
!
base = get_addr_base_and_unit_offset (base, &base_offset);
/* get_addr_base_and_unit_offset returns NULL for references with a variable
--- 1440,1446 ----
unsigned int align;
gcc_checking_assert (offset % BITS_PER_UNIT == 0);
! get_object_alignment_1 (base, &align, &misalign);
base = get_addr_base_and_unit_offset (base, &base_offset);
/* get_addr_base_and_unit_offset returns NULL for references with a variable
*************** build_ref_for_offset (location_t loc, tr
*** 1476,1497 ****
base = build_fold_addr_expr (unshare_expr (base));
}
! /* If prev_base were always an originally performed access
! we can extract more optimistic alignment information
! by looking at the access mode. That would constrain the
! alignment of base + base_offset which we would need to
! adjust according to offset. */
! if (!get_pointer_alignment_1 (base, &align, &misalign))
! {
! gcc_assert (misalign == 0);
! if (TREE_CODE (prev_base) == MEM_REF
! || TREE_CODE (prev_base) == TARGET_MEM_REF)
! align = TYPE_ALIGN (TREE_TYPE (prev_base));
! }
! misalign += (tree_to_double_int (off)
! .sext (TYPE_PRECISION (TREE_TYPE (off))).low
! * BITS_PER_UNIT);
! misalign = misalign & (align - 1);
if (misalign != 0)
align = (misalign & -misalign);
if (align < TYPE_ALIGN (exp_type))
--- 1479,1485 ----
base = build_fold_addr_expr (unshare_expr (base));
}
! misalign = (misalign + offset) & (align - 1);
if (misalign != 0)
align = (misalign & -misalign);
if (align < TYPE_ALIGN (exp_type))
