[gcc r12-6420] [vect] Re-analyze all modes for epilogues
Andre Simoes Dias Vieira
avieira@gcc.gnu.org
Mon Jan 10 18:12:04 GMT 2022
https://gcc.gnu.org/g:d3ff7420e941931d32ce2e332e7968fe67ba20af
commit r12-6420-gd3ff7420e941931d32ce2e332e7968fe67ba20af
Author: Andre Vieira <andre.simoesdiasvieira@arm.com>
Date: Thu Dec 2 14:34:15 2021 +0000
[vect] Re-analyze all modes for epilogues
gcc/ChangeLog:
* tree-vectorizer.c (better_epilogue_loop_than_p): Round factors up for
epilogue costing.
* tree-vect-loop.c (vect_analyze_loop): Re-analyze all modes for
epilogues, unless we are guaranteed that we can't have partial vectors.
* genopinit.c: (partial_vectors_supported): Generate new function.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/masked_epilogue.c: New test.
Diff:
---
gcc/genopinit.c | 28 ++++++++++
gcc/testsuite/gcc.target/aarch64/masked_epilogue.c | 10 ++++
gcc/tree-vect-loop.c | 63 ++++++++++------------
gcc/tree-vectorizer.c | 10 ++--
4 files changed, 72 insertions(+), 39 deletions(-)
diff --git a/gcc/genopinit.c b/gcc/genopinit.c
index c5cda286924..fe0791c27d6 100644
--- a/gcc/genopinit.c
+++ b/gcc/genopinit.c
@@ -320,6 +320,7 @@ main (int argc, const char **argv)
" signed char supports_vec_scatter_store[NUM_MACHINE_MODES];\n"
"};\n"
"extern void init_all_optabs (struct target_optabs *);\n"
+ "extern bool partial_vectors_supported_p (void);\n"
"\n"
"extern struct target_optabs default_target_optabs;\n"
"extern struct target_optabs *this_fn_optabs;\n"
@@ -372,6 +373,33 @@ main (int argc, const char **argv)
fprintf (s_file, " ena[%u] = HAVE_%s;\n", i, p->name);
fprintf (s_file, "}\n\n");
+ fprintf (s_file,
+ "/* Returns TRUE if the target supports any of the partial vector\n"
+ " optabs: while_ult_optab, len_load_optab or len_store_optab,\n"
+ " for any mode. */\n"
+ "bool\npartial_vectors_supported_p (void)\n{\n");
+ bool any_match = false;
+ fprintf (s_file, "\treturn");
+ bool first = true;
+ for (i = 0; patterns.iterate (i, &p); ++i)
+ {
+#define CMP_NAME(N) !strncmp (p->name, (N), strlen ((N)))
+ if (CMP_NAME("while_ult") || CMP_NAME ("len_load")
+ || CMP_NAME ("len_store"))
+ {
+ if (first)
+ fprintf (s_file, " HAVE_%s", p->name);
+ else
+ fprintf (s_file, " || HAVE_%s", p->name);
+ first = false;
+ any_match = true;
+ }
+ }
+ if (!any_match)
+ fprintf (s_file, " false");
+ fprintf (s_file, ";\n}\n");
+
+
/* Perform a binary search on a pre-encoded optab+mode*2. */
/* ??? Perhaps even better to generate a minimal perfect hash.
Using gperf directly is awkward since it's so geared to working
diff --git a/gcc/testsuite/gcc.target/aarch64/masked_epilogue.c b/gcc/testsuite/gcc.target/aarch64/masked_epilogue.c
new file mode 100644
index 00000000000..286a7be236f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/masked_epilogue.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ftree-vectorize -fdump-tree-vect-details -march=armv8-a+sve -msve-vector-bits=scalable" } */
+
+void f(unsigned char y[restrict],
+ unsigned char x[restrict], int n) {
+ for (int i = 0; i < n; ++i)
+ y[i] = (y[i] + x[i] + 1) >> 1;
+}
+
+/* { dg-final { scan-tree-dump {LOOP EPILOGUE VECTORIZED \(MODE=VNx} "vect" } } */
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 77f1cc0f788..6ed2b5f8724 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -2936,8 +2936,6 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
machine_mode autodetected_vector_mode = VOIDmode;
opt_loop_vec_info first_loop_vinfo = opt_loop_vec_info::success (NULL);
unsigned int mode_i = 0;
- unsigned int first_loop_i = 0;
- unsigned int first_loop_next_i = 0;
unsigned HOST_WIDE_INT simdlen = loop->simdlen;
/* First determine the main loop vectorization mode, either the first
@@ -2946,7 +2944,6 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
lowest cost if pick_lowest_cost_p. */
while (1)
{
- unsigned int loop_vinfo_i = mode_i;
bool fatal;
opt_loop_vec_info loop_vinfo
= vect_analyze_loop_1 (loop, shared, &loop_form_info,
@@ -2975,11 +2972,7 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
first_loop_vinfo = opt_loop_vec_info::success (NULL);
}
if (first_loop_vinfo == NULL)
- {
- first_loop_vinfo = loop_vinfo;
- first_loop_i = loop_vinfo_i;
- first_loop_next_i = mode_i;
- }
+ first_loop_vinfo = loop_vinfo;
else
{
delete loop_vinfo;
@@ -3025,32 +3018,37 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
/* Now analyze first_loop_vinfo for epilogue vectorization. */
poly_uint64 lowest_th = LOOP_VINFO_VERSIONING_THRESHOLD (first_loop_vinfo);
- /* Handle the case that the original loop can use partial
- vectorization, but want to only adopt it for the epilogue.
- The retry should be in the same mode as original. */
- if (LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P (first_loop_vinfo))
+ /* For epilogues start the analysis from the first mode. The motivation
+ behind starting from the beginning comes from cases where the VECTOR_MODES
+ array may contain length-agnostic and length-specific modes. Their
+ ordering is not guaranteed, so we could end up picking a mode for the main
+ loop that is after the epilogue's optimal mode. */
+ mode_i = 1;
+ bool supports_partial_vectors = partial_vectors_supported_p ();
+ poly_uint64 first_vinfo_vf = LOOP_VINFO_VECT_FACTOR (first_loop_vinfo);
+
+ while (1)
{
- gcc_assert (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (first_loop_vinfo)
- && !LOOP_VINFO_USING_PARTIAL_VECTORS_P (first_loop_vinfo));
+ /* If the target does not support partial vectors we can shorten the
+ number of modes to analyze for the epilogue as we know we can't pick a
+ mode that has at least as many NUNITS as the main loop's vectorization
+ factor, since that would imply the epilogue's vectorization factor
+ would be at least as high as the main loop's and we would be
+ vectorizing for more scalar iterations than there would be left. */
+ if (!supports_partial_vectors
+ && maybe_ge (GET_MODE_NUNITS (vector_modes[mode_i]), first_vinfo_vf))
+ {
+ mode_i++;
+ if (mode_i == vector_modes.length ())
+ break;
+ continue;
+ }
+
if (dump_enabled_p ())
dump_printf_loc (MSG_NOTE, vect_location,
- "***** Re-trying analysis with same vector mode"
- " %s for epilogue with partial vectors.\n",
- GET_MODE_NAME (first_loop_vinfo->vector_mode));
- mode_i = first_loop_i;
- }
- else
- {
- mode_i = first_loop_next_i;
- if (mode_i == vector_modes.length ())
- return first_loop_vinfo;
- }
-
- /* ??? If first_loop_vinfo was using VOIDmode then we probably
- want to instead search for the corresponding mode in vector_modes[]. */
+ "***** Re-trying epilogue analysis with vector "
+ "mode %s\n", GET_MODE_NAME (vector_modes[mode_i]));
- while (1)
- {
bool fatal;
opt_loop_vec_info loop_vinfo
= vect_analyze_loop_1 (loop, shared, &loop_form_info,
@@ -3102,11 +3100,6 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
if (mode_i == vector_modes.length ())
break;
- /* Try the next biggest vector size. */
- if (dump_enabled_p ())
- dump_printf_loc (MSG_NOTE, vect_location,
- "***** Re-trying epilogue analysis with vector "
- "mode %s\n", GET_MODE_NAME (vector_modes[mode_i]));
}
if (!first_loop_vinfo->epilogue_vinfos.is_empty ())
diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index e82750c29da..48eed40cae2 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -1887,11 +1887,13 @@ vector_costs::better_epilogue_loop_than_p (const vector_costs *other,
{
unsigned HOST_WIDE_INT main_vf_max
= estimated_poly_value (main_poly_vf, POLY_VALUE_MAX);
+ unsigned HOST_WIDE_INT other_vf_max
+ = estimated_poly_value (other_vf, POLY_VALUE_MAX);
+ unsigned HOST_WIDE_INT this_vf_max
+ = estimated_poly_value (this_vf, POLY_VALUE_MAX);
- other_factor = main_vf_max / estimated_poly_value (other_vf,
- POLY_VALUE_MAX);
- this_factor = main_vf_max / estimated_poly_value (this_vf,
- POLY_VALUE_MAX);
+ other_factor = CEIL (main_vf_max, other_vf_max);
+ this_factor = CEIL (main_vf_max, this_vf_max);
/* If the loop is not using partial vectors then it will iterate one
time less than one that does. It is safe to subtract one here,
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