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Re: [7/7] Pool alignment information for common bases
Richard Biener <richard.guenther@gmail.com> writes:
> On Tue, Jul 4, 2017 at 2:01 PM, Richard Sandiford
> <richard.sandiford@linaro.org> wrote:
>> Richard Biener <richard.guenther@gmail.com> writes:
>>> On Mon, Jul 3, 2017 at 9:49 AM, Richard Sandiford
>>> <richard.sandiford@linaro.org> wrote:
>>>> @@ -2070,8 +2143,7 @@ vect_find_same_alignment_drs (struct dat
>>>> if (dra == drb)
>>>> return;
>>>>
>>>> - if (!operand_equal_p (DR_BASE_OBJECT (dra), DR_BASE_OBJECT (drb),
>>>> - OEP_ADDRESS_OF)
>>>> + if (!operand_equal_p (DR_BASE_ADDRESS (dra), DR_BASE_ADDRESS (drb), 0)
>>>
>>> Why this change? It's semantically weaker after your change.
>>
>> It's because the DR_BASE_OBJECT comes from the access_fn analysis
>> while the DR_BASE_ADDRESS comes from the innermost_loop_behavior.
>> I hadn't realised when adding the original code how different the
>> two were, and since all the other parts are based on the
>> innermost_loop_behavior, I think this check should be too.
>> E.g. it doesn't really make sense to compare DR_INITs based
>> on DR_BASE_OBJECT.
>
> Ah ok, makes sense now.
>
>> I guess it should have been a separate patch though.
>
> No need.
>
>>>> || !operand_equal_p (DR_OFFSET (dra), DR_OFFSET (drb), 0)
>>>> || !operand_equal_p (DR_STEP (dra), DR_STEP (drb), 0))
>>>> return;
>>>> @@ -2129,6 +2201,7 @@ vect_analyze_data_refs_alignment (loop_v
>>>> vec<data_reference_p> datarefs = vinfo->datarefs;
>>>> struct data_reference *dr;
>>>>
>>>> + vect_record_base_alignments (vinfo);
>>>> FOR_EACH_VEC_ELT (datarefs, i, dr)
>>>> {
>>>> stmt_vec_info stmt_info = vinfo_for_stmt (DR_STMT (dr));
>>>> @@ -3327,7 +3400,8 @@ vect_analyze_data_refs (vec_info *vinfo,
>>>> {
>>>> struct data_reference *newdr
>>>> = create_data_ref (NULL, loop_containing_stmt (stmt),
>>>> - DR_REF (dr), stmt, maybe_scatter ? false : true);
>>>> + DR_REF (dr), stmt, !maybe_scatter,
>>>> + DR_IS_CONDITIONAL_IN_STMT (dr));
>>>> gcc_assert (newdr != NULL && DR_REF (newdr));
>>>> if (DR_BASE_ADDRESS (newdr)
>>>> && DR_OFFSET (newdr)
>>>> Index: gcc/tree-vect-slp.c
>>>> ===================================================================
>>>> --- gcc/tree-vect-slp.c 2017-07-03 08:20:56.404763323 +0100
>>>> +++ gcc/tree-vect-slp.c 2017-07-03 08:42:51.149380545 +0100
>>>> @@ -2358,6 +2358,7 @@ new_bb_vec_info (gimple_stmt_iterator re
>>>> gimple_stmt_iterator gsi;
>>>>
>>>> res = (bb_vec_info) xcalloc (1, sizeof (struct _bb_vec_info));
>>>> + new (&res->base_alignments) vec_base_alignments ();
>>>
>>> Ick. I'd rather make this proper C++ and do
>>>
>>> res = new _bb_vec_info;
>>>
>>> and add a constructor to the vec_info base initializing the hashtable.
>>> The above smells fishy.
>>
>> I knew I pushing my luck with that one. I just didn't want to have to
>> convert the current xcalloc of loop_vec_info into a long list of explicit
>> zero initializers. (OK, we have a lot of explicit zero assignments already,
>> but certainly some fields rely on the calloc zeroing.)
>>
>>> Looks like vec<> are happy with .create () being called on a zeroed struct.
>>>
>>> Alternatively add .create () to hashtable/map.
>>
>> The difference is that vec<> is explicitly meant to be POD, whereas
>> hash_map isn't (and I don't think we want it to be).
>
> Ah, indeed. So your patch makes *vec_info no longer POD (no problem
> but then use new/delete and constructors).
>
>> Ah well. I'll do a separate pre-patch to C++-ify the structures.
Here's an update that applies on top of the vec_info c++-ification patch
I just posted [ https://gcc.gnu.org/ml/gcc-patches/2017-07/msg01807.html ]
Tested as before. OK to install?
Thanks,
Richard
2017-07-27 Richard Sandiford <richard.sandiford@linaro.org>
gcc/
PR tree-optimization/81136
* tree-vectorizer.h: Include tree-hash-traits.h.
(vec_base_alignments): New typedef.
(vec_info): Add a base_alignments field.
(vect_record_base_alignments): Declare.
* tree-data-ref.h (data_reference): Add an is_conditional_in_stmt
field.
(DR_IS_CONDITIONAL_IN_STMT): New macro.
(create_data_ref): Add an is_conditional_in_stmt argument.
* tree-data-ref.c (create_data_ref): Likewise. Use it to initialize
the is_conditional_in_stmt field.
(data_ref_loc): Add an is_conditional_in_stmt field.
(get_references_in_stmt): Set the is_conditional_in_stmt field.
(find_data_references_in_stmt): Update call to create_data_ref.
(graphite_find_data_references_in_stmt): Likewise.
* tree-ssa-loop-prefetch.c (determine_loop_nest_reuse): Likewise.
* tree-vect-data-refs.c (vect_analyze_data_refs): Likewise.
(vect_record_base_alignment): New function.
(vect_record_base_alignments): Likewise.
(vect_compute_data_ref_alignment): Adjust base_addr and aligned_to
for nested statements even if we fail to compute a misalignment.
Use pooled base alignments for unconditional references.
(vect_find_same_alignment_drs): Compare base addresses instead
of base objects.
(vect_analyze_data_refs_alignment): Call vect_record_base_alignments.
* tree-vect-slp.c (vect_slp_analyze_bb_1): Likewise.
gcc/testsuite/
PR tree-optimization/81136
* gcc.dg/vect/pr81136.c: Add scan test.
Index: gcc/tree-vectorizer.h
===================================================================
--- gcc/tree-vectorizer.h 2017-07-27 13:46:58.376642483 +0100
+++ gcc/tree-vectorizer.h 2017-07-27 13:46:58.579633332 +0100
@@ -22,6 +22,7 @@ Software Foundation; either version 3, o
#define GCC_TREE_VECTORIZER_H
#include "tree-data-ref.h"
+#include "tree-hash-traits.h"
#include "target.h"
/* Used for naming of new temporaries. */
@@ -84,6 +85,11 @@ struct stmt_info_for_cost {
typedef vec<stmt_info_for_cost> stmt_vector_for_cost;
+/* Maps base addresses to an innermost_loop_behavior that gives the maximum
+ known alignment for that base. */
+typedef hash_map<tree_operand_hash,
+ innermost_loop_behavior *> vec_base_alignments;
+
/************************************************************************
SLP
************************************************************************/
@@ -169,6 +175,10 @@ struct vec_info {
/* All data references. Freed by free_data_refs, so not an auto_vec. */
vec<data_reference_p> datarefs;
+ /* Maps base addresses to an innermost_loop_behavior that gives the maximum
+ known alignment for that base. */
+ vec_base_alignments base_alignments;
+
/* All data dependences. Freed by free_dependence_relations, so not
an auto_vec. */
vec<ddr_p> ddrs;
@@ -1162,6 +1172,7 @@ extern bool vect_prune_runtime_alias_tes
extern bool vect_check_gather_scatter (gimple *, loop_vec_info,
gather_scatter_info *);
extern bool vect_analyze_data_refs (vec_info *, int *);
+extern void vect_record_base_alignments (vec_info *);
extern tree vect_create_data_ref_ptr (gimple *, tree, struct loop *, tree,
tree *, gimple_stmt_iterator *,
gimple **, bool, bool *,
Index: gcc/tree-data-ref.h
===================================================================
--- gcc/tree-data-ref.h 2017-07-27 13:46:58.376642483 +0100
+++ gcc/tree-data-ref.h 2017-07-27 13:46:58.578633377 +0100
@@ -159,6 +159,11 @@ struct data_reference
/* True when the data reference is in RHS of a stmt. */
bool is_read;
+ /* True when the data reference is conditional within STMT,
+ i.e. if it might not occur even when the statement is executed
+ and runs to completion. */
+ bool is_conditional_in_stmt;
+
/* Behavior of the memory reference in the innermost loop. */
struct innermost_loop_behavior innermost;
@@ -178,6 +183,7 @@ #define DR_ACCESS_FN(DR, I) DR_AC
#define DR_NUM_DIMENSIONS(DR) DR_ACCESS_FNS (DR).length ()
#define DR_IS_READ(DR) (DR)->is_read
#define DR_IS_WRITE(DR) (!DR_IS_READ (DR))
+#define DR_IS_CONDITIONAL_IN_STMT(DR) (DR)->is_conditional_in_stmt
#define DR_BASE_ADDRESS(DR) (DR)->innermost.base_address
#define DR_OFFSET(DR) (DR)->innermost.offset
#define DR_INIT(DR) (DR)->innermost.init
@@ -434,7 +440,8 @@ extern bool graphite_find_data_reference
vec<data_reference_p> *);
tree find_data_references_in_loop (struct loop *, vec<data_reference_p> *);
bool loop_nest_has_data_refs (loop_p loop);
-struct data_reference *create_data_ref (loop_p, loop_p, tree, gimple *, bool);
+struct data_reference *create_data_ref (loop_p, loop_p, tree, gimple *, bool,
+ bool);
extern bool find_loop_nest (struct loop *, vec<loop_p> *);
extern struct data_dependence_relation *initialize_data_dependence_relation
(struct data_reference *, struct data_reference *, vec<loop_p>);
Index: gcc/tree-data-ref.c
===================================================================
--- gcc/tree-data-ref.c 2017-07-27 13:46:58.376642483 +0100
+++ gcc/tree-data-ref.c 2017-07-27 13:46:58.577633422 +0100
@@ -1125,15 +1125,19 @@ free_data_ref (data_reference_p dr)
free (dr);
}
-/* Analyzes memory reference MEMREF accessed in STMT. The reference
- is read if IS_READ is true, write otherwise. Returns the
- data_reference description of MEMREF. NEST is the outermost loop
- in which the reference should be instantiated, LOOP is the loop in
- which the data reference should be analyzed. */
+/* Analyze memory reference MEMREF, which is accessed in STMT.
+ The reference is a read if IS_READ is true, otherwise it is a write.
+ IS_CONDITIONAL_IN_STMT indicates that the reference is conditional
+ within STMT, i.e. that it might not occur even if STMT is executed
+ and runs to completion.
+
+ Return the data_reference description of MEMREF. NEST is the outermost
+ loop in which the reference should be instantiated, LOOP is the loop
+ in which the data reference should be analyzed. */
struct data_reference *
create_data_ref (loop_p nest, loop_p loop, tree memref, gimple *stmt,
- bool is_read)
+ bool is_read, bool is_conditional_in_stmt)
{
struct data_reference *dr;
@@ -1148,6 +1152,7 @@ create_data_ref (loop_p nest, loop_p loo
DR_STMT (dr) = stmt;
DR_REF (dr) = memref;
DR_IS_READ (dr) = is_read;
+ DR_IS_CONDITIONAL_IN_STMT (dr) = is_conditional_in_stmt;
dr_analyze_innermost (&DR_INNERMOST (dr), memref,
nest != NULL ? loop : NULL);
@@ -4774,6 +4779,11 @@ struct data_ref_loc
/* True if the memory reference is read. */
bool is_read;
+
+ /* True if the data reference is conditional within the containing
+ statement, i.e. if it might not occur even when the statement
+ is executed and runs to completion. */
+ bool is_conditional_in_stmt;
};
@@ -4840,6 +4850,7 @@ get_references_in_stmt (gimple *stmt, ve
{
ref.ref = op1;
ref.is_read = true;
+ ref.is_conditional_in_stmt = false;
references->safe_push (ref);
}
}
@@ -4867,6 +4878,7 @@ get_references_in_stmt (gimple *stmt, ve
type = TREE_TYPE (gimple_call_arg (stmt, 3));
if (TYPE_ALIGN (type) != align)
type = build_aligned_type (type, align);
+ ref.is_conditional_in_stmt = true;
ref.ref = fold_build2 (MEM_REF, type, gimple_call_arg (stmt, 0),
ptr);
references->safe_push (ref);
@@ -4886,6 +4898,7 @@ get_references_in_stmt (gimple *stmt, ve
{
ref.ref = op1;
ref.is_read = true;
+ ref.is_conditional_in_stmt = false;
references->safe_push (ref);
}
}
@@ -4899,6 +4912,7 @@ get_references_in_stmt (gimple *stmt, ve
{
ref.ref = op0;
ref.is_read = false;
+ ref.is_conditional_in_stmt = false;
references->safe_push (ref);
}
return clobbers_memory;
@@ -4963,8 +4977,8 @@ find_data_references_in_stmt (struct loo
FOR_EACH_VEC_ELT (references, i, ref)
{
- dr = create_data_ref (nest, loop_containing_stmt (stmt),
- ref->ref, stmt, ref->is_read);
+ dr = create_data_ref (nest, loop_containing_stmt (stmt), ref->ref,
+ stmt, ref->is_read, ref->is_conditional_in_stmt);
gcc_assert (dr != NULL);
datarefs->safe_push (dr);
}
@@ -4993,7 +5007,8 @@ graphite_find_data_references_in_stmt (l
FOR_EACH_VEC_ELT (references, i, ref)
{
- dr = create_data_ref (nest, loop, ref->ref, stmt, ref->is_read);
+ dr = create_data_ref (nest, loop, ref->ref, stmt, ref->is_read,
+ ref->is_conditional_in_stmt);
gcc_assert (dr != NULL);
datarefs->safe_push (dr);
}
Index: gcc/tree-ssa-loop-prefetch.c
===================================================================
--- gcc/tree-ssa-loop-prefetch.c 2017-07-27 13:46:58.376642483 +0100
+++ gcc/tree-ssa-loop-prefetch.c 2017-07-27 13:46:58.578633377 +0100
@@ -1633,7 +1633,7 @@ determine_loop_nest_reuse (struct loop *
for (ref = gr->refs; ref; ref = ref->next)
{
dr = create_data_ref (nest, loop_containing_stmt (ref->stmt),
- ref->mem, ref->stmt, !ref->write_p);
+ ref->mem, ref->stmt, !ref->write_p, false);
if (dr)
{
Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c 2017-07-27 13:46:58.376642483 +0100
+++ gcc/tree-vect-data-refs.c 2017-07-27 13:46:58.579633332 +0100
@@ -708,6 +708,69 @@ vect_slp_analyze_instance_dependence (sl
return res;
}
+/* Record in VINFO the base alignment guarantee given by DRB. STMT is
+ the statement that contains DRB, which is useful for recording in the
+ dump file. */
+
+static void
+vect_record_base_alignment (vec_info *vinfo, gimple *stmt,
+ innermost_loop_behavior *drb)
+{
+ bool existed;
+ innermost_loop_behavior *&entry
+ = vinfo->base_alignments.get_or_insert (drb->base_address, &existed);
+ if (!existed || entry->base_alignment < drb->base_alignment)
+ {
+ entry = drb;
+ if (dump_enabled_p ())
+ {
+ dump_printf_loc (MSG_NOTE, vect_location,
+ "recording new base alignment for ");
+ dump_generic_expr (MSG_NOTE, TDF_SLIM, drb->base_address);
+ dump_printf (MSG_NOTE, "\n");
+ dump_printf_loc (MSG_NOTE, vect_location,
+ " alignment: %d\n", drb->base_alignment);
+ dump_printf_loc (MSG_NOTE, vect_location,
+ " misalignment: %d\n", drb->base_misalignment);
+ dump_printf_loc (MSG_NOTE, vect_location,
+ " based on: ");
+ dump_gimple_stmt (MSG_NOTE, TDF_SLIM, stmt, 0);
+ }
+ }
+}
+
+/* If the region we're going to vectorize is reached, all unconditional
+ data references occur at least once. We can therefore pool the base
+ alignment guarantees from each unconditional reference. Do this by
+ going through all the data references in VINFO and checking whether
+ the containing statement makes the reference unconditionally. If so,
+ record the alignment of the base address in VINFO so that it can be
+ used for all other references with the same base. */
+
+void
+vect_record_base_alignments (vec_info *vinfo)
+{
+ loop_vec_info loop_vinfo = dyn_cast <loop_vec_info> (vinfo);
+ struct loop *loop = loop_vinfo ? LOOP_VINFO_LOOP (loop_vinfo) : NULL;
+ data_reference *dr;
+ unsigned int i;
+ FOR_EACH_VEC_ELT (vinfo->datarefs, i, dr)
+ if (!DR_IS_CONDITIONAL_IN_STMT (dr))
+ {
+ gimple *stmt = DR_STMT (dr);
+ vect_record_base_alignment (vinfo, stmt, &DR_INNERMOST (dr));
+
+ /* If DR is nested in the loop that is being vectorized, we can also
+ record the alignment of the base wrt the outer loop. */
+ if (loop && nested_in_vect_loop_p (loop, stmt))
+ {
+ stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
+ vect_record_base_alignment
+ (vinfo, stmt, &STMT_VINFO_DR_WRT_VEC_LOOP (stmt_info));
+ }
+ }
+}
+
/* Function vect_compute_data_ref_alignment
Compute the misalignment of the data reference DR.
@@ -725,6 +788,7 @@ vect_compute_data_ref_alignment (struct
{
gimple *stmt = DR_STMT (dr);
stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
+ vec_base_alignments *base_alignments = &stmt_info->vinfo->base_alignments;
loop_vec_info loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_info);
struct loop *loop = NULL;
tree ref = DR_REF (dr);
@@ -793,6 +857,15 @@ vect_compute_data_ref_alignment (struct
unsigned int base_misalignment = drb->base_misalignment;
unsigned HOST_WIDE_INT vector_alignment = TYPE_ALIGN_UNIT (vectype);
+ /* Calculate the maximum of the pooled base address alignment and the
+ alignment that we can compute for DR itself. */
+ innermost_loop_behavior **entry = base_alignments->get (drb->base_address);
+ if (entry && base_alignment < (*entry)->base_alignment)
+ {
+ base_alignment = (*entry)->base_alignment;
+ base_misalignment = (*entry)->base_misalignment;
+ }
+
if (drb->offset_alignment < vector_alignment
|| !step_preserves_misalignment_p
/* We need to know whether the step wrt the vectorized loop is
@@ -2113,8 +2186,7 @@ vect_find_same_alignment_drs (struct dat
if (dra == drb)
return;
- if (!operand_equal_p (DR_BASE_OBJECT (dra), DR_BASE_OBJECT (drb),
- OEP_ADDRESS_OF)
+ if (!operand_equal_p (DR_BASE_ADDRESS (dra), DR_BASE_ADDRESS (drb), 0)
|| !operand_equal_p (DR_OFFSET (dra), DR_OFFSET (drb), 0)
|| !operand_equal_p (DR_STEP (dra), DR_STEP (drb), 0))
return;
@@ -2172,6 +2244,7 @@ vect_analyze_data_refs_alignment (loop_v
vec<data_reference_p> datarefs = vinfo->datarefs;
struct data_reference *dr;
+ vect_record_base_alignments (vinfo);
FOR_EACH_VEC_ELT (datarefs, i, dr)
{
stmt_vec_info stmt_info = vinfo_for_stmt (DR_STMT (dr));
@@ -3437,7 +3510,8 @@ vect_analyze_data_refs (vec_info *vinfo,
{
struct data_reference *newdr
= create_data_ref (NULL, loop_containing_stmt (stmt),
- DR_REF (dr), stmt, maybe_scatter ? false : true);
+ DR_REF (dr), stmt, !maybe_scatter,
+ DR_IS_CONDITIONAL_IN_STMT (dr));
gcc_assert (newdr != NULL && DR_REF (newdr));
if (DR_BASE_ADDRESS (newdr)
&& DR_OFFSET (newdr)
Index: gcc/tree-vect-slp.c
===================================================================
--- gcc/tree-vect-slp.c 2017-07-27 13:46:58.376642483 +0100
+++ gcc/tree-vect-slp.c 2017-07-27 13:46:58.579633332 +0100
@@ -2764,6 +2764,8 @@ vect_slp_analyze_bb_1 (gimple_stmt_itera
return NULL;
}
+ vect_record_base_alignments (bb_vinfo);
+
/* Analyze and verify the alignment of data references and the
dependence in the SLP instances. */
for (i = 0; BB_VINFO_SLP_INSTANCES (bb_vinfo).iterate (i, &instance); )
Index: gcc/testsuite/gcc.dg/vect/pr81136.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr81136.c 2017-07-27 13:46:58.376642483 +0100
+++ gcc/testsuite/gcc.dg/vect/pr81136.c 2017-07-27 13:46:58.577633422 +0100
@@ -14,3 +14,5 @@ fn1 (int n)
for (int i = 0; i < n; i++)
a->bar[i] = b[i];
}
+
+/* { dg-final { scan-tree-dump-not "Unknown misalignment" "vect" } } */