On 17 May 2016 at 18:36, Richard Biener <rguent...@suse.de> wrote:
> On Wed, 11 May 2016, Prathamesh Kulkarni wrote:
>
>> On 6 May 2016 at 17:20, Richard Biener <rguent...@suse.de> wrote:
>> >
>> > You can't simply use
>> >
>> > + offset = int_byte_position (field);
>> >
>> > as it can be placed at variable offset which will make int_byte_position
>> > ICE. Note it also returns a truncated byte position (bit position
>> > stripped) which may be undesirable here. I think you want to use
>> > bit_position and if and only if DECL_FIELD_OFFSET and
>> > DECL_FIELD_BIT_OFFSET are INTEGER_CST.
>> oops, I didn't realize offsets could be variable.
>> Will that be the case only for VLA member inside struct ?
>
> And non-VLA members after such member.
>
>> > Your observation about the expensiveness of the walk still stands I guess
>> > and eventually you should at least cache the
>> > get_vec_alignment_for_record_decl cases. Please make those workers
>> > _type rather than _decl helpers.
>> Done
>> >
>> > You seem to simply get at the maximum vectorized field/array element
>> > alignment possible for all arrays - you could restrict that to
>> > arrays with at least vector size (as followup).
>> Um sorry, I didn't understand this part.
>
> It doesn't make sense to align
>
> struct { int a; int b; int c; int d; float b[3]; int e; };
>
> because we have a float[3] member. There is no vector size that
> would cover the float[3] array.
Thanks for the explanation.
So we do not want to align struct if sizeof (array_field) < sizeof
(vector_type).
This issue is also present without patch for global arrays, so I modified
get_vec_alignment_for_array_type, to return 0 if sizeof (array_type) <
sizeof (vectype).
>
>> >
>> > + /* Skip artificial decls like typeinfo decls or if
>> > + record is packed. */
>> > + if (DECL_ARTIFICIAL (record_decl) || TYPE_PACKED (type))
>> > + return 0;
>> >
>> > I think we should honor DECL_USER_ALIGN as well and not mess with those
>> > decls.
>> Done
>> >
>> > Given the patch now does quite some extra work it might make sense
>> > to split the symtab part out of the vect_can_force_dr_alignment_p
>> > predicate and call that early.
>> In the patch I call symtab_node::can_increase_alignment_p early. I tried
>> moving that to it's callers - vect_compute_data_ref_alignment and
>> increase_alignment::execute, however that failed some tests in vect, and
>> hence I didn't add the following hunk in the patch. Did I miss some
>> check ?
>
> Not sure.
>
>> diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
>> index 7652e21..2c1acee 100644
>> --- a/gcc/tree-vect-data-refs.c
>> +++ b/gcc/tree-vect-data-refs.c
>> @@ -795,7 +795,10 @@ vect_compute_data_ref_alignment (struct data_reference
>> *dr)
>> && TREE_CODE (TREE_OPERAND (base, 0)) == ADDR_EXPR)
>> base = TREE_OPERAND (TREE_OPERAND (base, 0), 0);
>>
>> - if (!vect_can_force_dr_alignment_p (base, TYPE_ALIGN (vectype)))
>> + if (!(TREE_CODE (base) == VAR_DECL
>> + && decl_in_symtab_p (base)
>> + && symtab_node::get (base)->can_increase_alignment_p ()
>> + && vect_can_force_dr_alignment_p (base, TYPE_ALIGN (vectype))))
>> {
>> if (dump_enabled_p ())
>> {
>
> + for (tree field = first_field (type);
> + field != NULL_TREE;
> + field = DECL_CHAIN (field))
> + {
> + /* Skip if not FIELD_DECL or has variable offset. */
> + if (TREE_CODE (field) != FIELD_DECL
> + || TREE_CODE (DECL_FIELD_OFFSET (field)) != INTEGER_CST
> + || TREE_CODE (DECL_FIELD_BIT_OFFSET (field)) != INTEGER_CST
> + || DECL_USER_ALIGN (field)
> + || DECL_ARTIFICIAL (field))
> + continue;
>
> you can stop processing the type and return 0 here if the offset
> is not an INTEGER_CST. All following fields will have the same issue.
>
> + /* FIXME: is this check necessary since we check for variable
> offset above ? */
> + if (TREE_CODE (offset_tree) != INTEGER_CST)
> + continue;
>
> the check should not be necessary.
>
> offset = tree_to_uhwi (offset_tree);
>
> but in theory offset_tree might not fit a unsigned HOST_WIDE_INT, so
> instead of for INTEGER_CST please check ! tree_fits_uhwi_p (offset_tree).
> As above all following fields will also fail the check if this fails so
> you can return 0 early.
>
> +static unsigned
> +get_vec_alignment_for_type (tree type)
> +{
> + if (type == NULL_TREE)
> + return 0;
> +
> + gcc_assert (TYPE_P (type));
> +
> + unsigned *slot = type_align_map->get (type);
> + if (slot)
> + return *slot;
>
> I suggest to apply the caching only for the RECORD_TYPE case to keep
> the size of the map low.
>
> Otherwise the patch looks ok now.
I have done the suggested changes in attached patch.
Is this version OK to commit after bootstrap+test ?
The patch survives cross-testing on arm*-*-* and aarch64*-*-*.Thanks, Prathamesh > > Thanks, > Richard.
diff --git a/gcc/testsuite/gcc.dg/vect/section-anchors-vect-70.c
b/gcc/testsuite/gcc.dg/vect/section-anchors-vect-70.c
new file mode 100644
index 0000000..7010a52
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/section-anchors-vect-70.c
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target section_anchors } */
+/* { dg-require-effective-target vect_int } */
+
+#define N 32
+
+/* Increase alignment of struct if an array's offset is multiple of alignment
of
+ vector type corresponding to it's scalar type.
+ For the below test-case:
+ offsetof(e) == 8 bytes.
+ i) For arm: let x = alignment of vector type corresponding to int,
+ x == 8 bytes.
+ Since offsetof(e) % x == 0, set DECL_ALIGN(a, b, c) to x.
+ ii) For aarch64, ppc: x == 16 bytes.
+ Since offsetof(e) % x != 0, don't increase alignment of a, b, c.
+*/
+
+static struct A {
+ int p1, p2;
+ int e[N];
+} a, b, c;
+
+int foo(void)
+{
+ for (int i = 0; i < N; i++)
+ a.e[i] = b.e[i] + c.e[i];
+
+ return a.e[0];
+}
+
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0
"increase_alignment" { target aarch64*-*-* } } } */
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0
"increase_alignment" { target powerpc64*-*-* } } } */
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 3
"increase_alignment" { target arm*-*-* } } } */
diff --git a/gcc/testsuite/gcc.dg/vect/section-anchors-vect-71.c
b/gcc/testsuite/gcc.dg/vect/section-anchors-vect-71.c
new file mode 100644
index 0000000..7cbd1dc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/section-anchors-vect-71.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target section_anchors } */
+/* { dg-require-effective-target vect_int } */
+
+/* Should not increase alignment of the struct because
+ sizeof (A.e) < sizeof(corresponding vector type). */
+
+#define N 3
+
+static struct A {
+ int p1, p2;
+ int e[N];
+} a, b, c;
+
+int foo(void)
+{
+ for (int i = 0; i < N; i++)
+ a.e[i] = b.e[i] + c.e[i];
+
+ return a.e[0];
+}
+
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0
"increase_alignment" { target aarch64*-*-* } } } */
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0
"increase_alignment" { target powerpc64*-*-* } } } */
+/* { dg-final { scan-ipa-dump-times "Increasing alignment of decl" 0
"increase_alignment" { target arm*-*-* } } } */
diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index 2b25b45..09b70bc 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -794,38 +793,157 @@ make_pass_slp_vectorize (gcc::context *ctxt)
This should involve global alignment analysis and in the future also
array padding. */
+static unsigned get_vec_alignment_for_type (tree);
+static hash_map<tree, unsigned> *type_align_map;
+
+/* Return alignment of array's vector type corresponding to scalar type.
+ 0 if no vector type exists. */
+static unsigned
+get_vec_alignment_for_array_type (tree type)
+{
+ gcc_assert (TREE_CODE (type) == ARRAY_TYPE);
+
+ tree vectype = get_vectype_for_scalar_type (strip_array_types (type));
+ if (!vectype)
+ return 0;
+
+ tree type_size_tree = TYPE_SIZE (type);
+ if (!type_size_tree)
+ return TYPE_ALIGN (vectype);
+
+ if (TREE_CODE (type_size_tree) != INTEGER_CST)
+ return TYPE_ALIGN (vectype);
+
+ /* If array has constant size, ensure that it's at least equal to
+ size of vector type. */
+ if (!tree_fits_uhwi_p (type_size_tree))
+ return TYPE_ALIGN (vectype);
+ unsigned HOST_WIDE_INT type_size = tree_to_uhwi (type_size_tree);
+
+ tree vectype_size_tree = TYPE_SIZE (vectype);
+ if (!tree_fits_uhwi_p (vectype_size_tree))
+ return TYPE_ALIGN (vectype);
+
+ unsigned HOST_WIDE_INT vectype_size = tree_to_uhwi (vectype_size_tree);
+ return (type_size > vectype_size) ? TYPE_ALIGN (vectype) : 0;
+}
+
+/* Return alignment of field having maximum alignment of vector type
+ corresponding to it's scalar type. For now, we only consider fields whose
+ offset is a multiple of it's vector alignment.
+ 0 if no suitable field is found. */
+static unsigned
+get_vec_alignment_for_record_type (tree type)
+{
+ gcc_assert (TREE_CODE (type) == RECORD_TYPE);
+
+ unsigned *slot = type_align_map->get (type);
+ if (slot)
+ return *slot;
+
+ unsigned max_align = 0, alignment;
+ HOST_WIDE_INT offset;
+ tree offset_tree;
+
+ if (TYPE_PACKED (type))
+ return 0;
+
+ for (tree field = first_field (type);
+ field != NULL_TREE;
+ field = DECL_CHAIN (field))
+ {
+ /* Skip if not FIELD_DECL or if alignment is set by user. */
+ if (TREE_CODE (field) != FIELD_DECL
+ || DECL_USER_ALIGN (field)
+ || DECL_ARTIFICIAL (field))
+ continue;
+
+ /* We don't need to process the type further if offset is variable,
+ since the offsets of remaining members will also be variable. */
+ if (TREE_CODE (DECL_FIELD_OFFSET (field)) != INTEGER_CST
+ || TREE_CODE (DECL_FIELD_BIT_OFFSET (field)) != INTEGER_CST)
+ return 0;
+
+ /* Similarly stop processing the type if offset_tree
+ does not fit in unsigned HOST_WIDE_INT. */
+ offset_tree = bit_position (field);
+ if (!tree_fits_uhwi_p (offset_tree))
+ return 0;
+
+ offset = tree_to_uhwi (offset_tree);
+ alignment = get_vec_alignment_for_type (TREE_TYPE (field));
+
+ /* Get maximum alignment of vectorized field/array among those members
+ whose offset is multiple of the vector alignment. */
+ if (alignment
+ && (offset % alignment == 0)
+ && (alignment > max_align))
+ max_align = alignment;
+ }
+
+ type_align_map->put (type, max_align);
+ return max_align;
+}
+
+/* Return alignment of vector type corresponding to decl's scalar type
+ or 0 if it doesn't exist or the vector alignment is lesser than
+ decl's alignment. */
+static unsigned
+get_vec_alignment_for_type (tree type)
+{
+ if (type == NULL_TREE)
+ return 0;
+
+ gcc_assert (TYPE_P (type));
+
+ static unsigned alignment = 0;
+ switch (TREE_CODE (type))
+ {
+ case ARRAY_TYPE:
+ alignment = get_vec_alignment_for_array_type (type);
+ break;
+ case RECORD_TYPE:
+ alignment = get_vec_alignment_for_record_type (type);
+ break;
+ default:
+ alignment = 0;
+ break;
+ }
+
+ return (alignment > TYPE_ALIGN (type)) ? alignment : 0;
+}
+
+/* Entry point to increase_alignment pass. */
static unsigned int
increase_alignment (void)
{
varpool_node *vnode;
vect_location = UNKNOWN_LOCATION;
+ type_align_map = new hash_map<tree, unsigned>;
/* Increase the alignment of all global arrays for vectorization. */
FOR_EACH_DEFINED_VARIABLE (vnode)
{
- tree vectype, decl = vnode->decl;
- tree t;
+ tree decl = vnode->decl;
unsigned int alignment;
- t = TREE_TYPE (decl);
- if (TREE_CODE (t) != ARRAY_TYPE)
- continue;
- vectype = get_vectype_for_scalar_type (strip_array_types (t));
- if (!vectype)
- continue;
- alignment = TYPE_ALIGN (vectype);
- if (DECL_ALIGN (decl) >= alignment)
- continue;
-
- if (vect_can_force_dr_alignment_p (decl, alignment))
+ if ((decl_in_symtab_p (decl)
+ && !symtab_node::get (decl)->can_increase_alignment_p ())
+ || DECL_USER_ALIGN (decl) || DECL_ARTIFICIAL (decl))
+ continue;
+
+ alignment = get_vec_alignment_for_type (TREE_TYPE (decl));
+ if (alignment && vect_can_force_dr_alignment_p (decl, alignment))
{
- vnode->increase_alignment (TYPE_ALIGN (vectype));
+ vnode->increase_alignment (alignment);
dump_printf (MSG_NOTE, "Increasing alignment of decl: ");
dump_generic_expr (MSG_NOTE, TDF_SLIM, decl);
dump_printf (MSG_NOTE, "\n");
}
}
+
+ delete type_align_map;
return 0;
}
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