A later patch adds base alignment information to innermost_loop_behavior.
After that, the only remaining piece of alignment information that wasn't
immediately obvious was the step alignment. Adding that allows a minor
simplification to vect_compute_data_ref_alignment, and also potentially
improves the handling of variable strides for outer loop vectorisation.
A later patch will also use it to give the alignment of the DR as a whole.
Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install?
Richard
2017-07-03 Richard Sandiford <richard.sandif...@linaro.org>
gcc/
* tree-data-ref.h (innermost_loop_behavior): Add a step_alignment
field.
(DR_STEP_ALIGNMENT): New macro.
* tree-vectorizer.h (STMT_VINFO_DR_STEP_ALIGNMENT): Likewise.
* tree-data-ref.c (dr_analyze_innermost): Initalize step_alignment.
(create_data_ref): Print it.
* tree-vect-stmts.c (vectorizable_load): Use the step alignment
to tell whether the step preserves vector (mis)alignment.
* tree-vect-data-refs.c (vect_compute_data_ref_alignment): Likewise.
Move the check for an integer step and generalise to all INTEGER_CST.
(vect_analyze_data_refs): Set DR_STEP_ALIGNMENT when setting DR_STEP.
Print the outer step alignment.
Index: gcc/tree-data-ref.h
===================================================================
--- gcc/tree-data-ref.h 2017-07-03 07:51:31.005161213 +0100
+++ gcc/tree-data-ref.h 2017-07-03 07:52:14.194782203 +0100
@@ -56,6 +56,9 @@ struct innermost_loop_behavior
high value if the offset is zero. This is a byte rather than a bit
quantity. */
unsigned int offset_alignment;
+
+ /* Likewise for STEP. */
+ unsigned int step_alignment;
};
/* Describes the evolutions of indices of the memory reference. The indices
@@ -145,6 +148,7 @@ #define DR_INIT(DR) (DR)-
#define DR_STEP(DR) (DR)->innermost.step
#define DR_PTR_INFO(DR) (DR)->alias.ptr_info
#define DR_OFFSET_ALIGNMENT(DR) (DR)->innermost.offset_alignment
+#define DR_STEP_ALIGNMENT(DR) (DR)->innermost.step_alignment
#define DR_INNERMOST(DR) (DR)->innermost
typedef struct data_reference *data_reference_p;
Index: gcc/tree-vectorizer.h
===================================================================
--- gcc/tree-vectorizer.h 2017-07-03 07:51:31.006161241 +0100
+++ gcc/tree-vectorizer.h 2017-07-03 07:52:14.196782157 +0100
@@ -709,6 +709,8 @@ #define STMT_VINFO_DR_OFFSET(S)
#define STMT_VINFO_DR_STEP(S) (S)->dr_wrt_vec_loop.step
#define STMT_VINFO_DR_OFFSET_ALIGNMENT(S) \
(S)->dr_wrt_vec_loop.offset_alignment
+#define STMT_VINFO_DR_STEP_ALIGNMENT(S) \
+ (S)->dr_wrt_vec_loop.step_alignment
#define STMT_VINFO_IN_PATTERN_P(S) (S)->in_pattern_p
#define STMT_VINFO_RELATED_STMT(S) (S)->related_stmt
Index: gcc/tree-data-ref.c
===================================================================
--- gcc/tree-data-ref.c 2017-07-03 07:51:31.004161185 +0100
+++ gcc/tree-data-ref.c 2017-07-03 07:52:14.193782226 +0100
@@ -870,6 +870,7 @@ dr_analyze_innermost (struct data_refere
drb->init = init;
drb->step = step;
drb->offset_alignment = highest_pow2_factor (offset_iv.base);
+ drb->step_alignment = highest_pow2_factor (step);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "success.\n");
@@ -1085,6 +1086,7 @@ create_data_ref (loop_p nest, loop_p loo
print_generic_expr (dump_file, DR_STEP (dr), TDF_SLIM);
fprintf (dump_file, "\n\toffset alignment: %d",
DR_OFFSET_ALIGNMENT (dr));
+ fprintf (dump_file, "\n\tstep alignment: %d", DR_STEP_ALIGNMENT (dr));
fprintf (dump_file, "\n\tbase_object: ");
print_generic_expr (dump_file, DR_BASE_OBJECT (dr), TDF_SLIM);
fprintf (dump_file, "\n");
Index: gcc/tree-vect-stmts.c
===================================================================
--- gcc/tree-vect-stmts.c 2017-07-03 07:51:05.480852682 +0100
+++ gcc/tree-vect-stmts.c 2017-07-03 07:52:14.195782180 +0100
@@ -7294,8 +7294,7 @@ vectorizable_load (gimple *stmt, gimple_
nested within an outer-loop that is being vectorized. */
if (nested_in_vect_loop
- && (TREE_INT_CST_LOW (DR_STEP (dr))
- % GET_MODE_SIZE (TYPE_MODE (vectype)) != 0))
+ && (DR_STEP_ALIGNMENT (dr) % GET_MODE_SIZE (TYPE_MODE (vectype))) != 0)
{
gcc_assert (alignment_support_scheme != dr_explicit_realign_optimized);
compute_in_loop = true;
Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c 2017-07-03 07:51:31.006161241 +0100
+++ gcc/tree-vect-data-refs.c 2017-07-03 07:52:14.194782203 +0100
@@ -698,10 +698,9 @@ vect_compute_data_ref_alignment (struct
divides by the vector size. */
else if (nested_in_vect_loop_p (loop, stmt))
{
- tree step = DR_STEP (dr);
step_preserves_misalignment_p
- = (tree_fits_shwi_p (step)
- && tree_to_shwi (step) % GET_MODE_SIZE (TYPE_MODE (vectype)) == 0);
+ = (DR_STEP_ALIGNMENT (dr)
+ % GET_MODE_SIZE (TYPE_MODE (vectype))) == 0;
if (dump_enabled_p ())
{
@@ -720,12 +719,10 @@ vect_compute_data_ref_alignment (struct
the dataref evenly divides by the vector size. */
else
{
- tree step = DR_STEP (dr);
unsigned vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
step_preserves_misalignment_p
- = (tree_fits_shwi_p (step)
- && ((tree_to_shwi (step) * vf)
- % GET_MODE_SIZE (TYPE_MODE (vectype)) == 0));
+ = ((DR_STEP_ALIGNMENT (dr) * vf)
+ % GET_MODE_SIZE (TYPE_MODE (vectype))) == 0;
if (!step_preserves_misalignment_p && dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -773,7 +770,10 @@ vect_compute_data_ref_alignment (struct
alignment = TYPE_ALIGN_UNIT (vectype);
if (drb->offset_alignment < alignment
- || !step_preserves_misalignment_p)
+ || !step_preserves_misalignment_p
+ /* We need to know whether the step wrt the vectorized loop is
+ negative when computing the starting misalignment below. */
+ || TREE_CODE (drb->step) != INTEGER_CST)
{
if (dump_enabled_p ())
{
@@ -3414,6 +3414,8 @@ vect_analyze_data_refs (vec_info *vinfo,
DR_STEP (newdr) = step;
DR_OFFSET_ALIGNMENT (newdr)
= BIGGEST_ALIGNMENT;
+ DR_STEP_ALIGNMENT (newdr)
+ = highest_pow2_factor (step);
dr = newdr;
simd_lane_access = true;
}
@@ -3665,6 +3667,8 @@ vect_analyze_data_refs (vec_info *vinfo,
STMT_VINFO_DR_STEP (stmt_info));
dump_printf (MSG_NOTE, "\n\touter offset alignment: %d\n",
STMT_VINFO_DR_OFFSET_ALIGNMENT (stmt_info));
+ dump_printf (MSG_NOTE, "\n\touter step alignment: %d\n",
+ STMT_VINFO_DR_STEP_ALIGNMENT (stmt_info));
}
}
