[PATCH] aarch64: modify Ampere CPU tunings on reassociation/FMA

[Di Zhao OS]

This patch modifies tunings for ampere1/ampere1a/ampere1b, to:

1. Allow reassociation on FP additions.
2. Avoid generating loop-dependant FMA chains. Added a tuning
option for this.

Bootstrapped and tested. Is this ok for trunk?

Thanks,
Di Zhao

gcc/ChangeLog:

        * config/aarch64/aarch64-tuning-flags.def (AARCH64_EXTRA_TUNING_OPTION):
        New tuing option to avoid cross-loop FMA.
        * config/aarch64/aarch64.cc (aarch64_override_options_internal): Set
        param_avoid_fma_max_bits according to tuning option.
        * config/aarch64/tuning_models/ampere1.h: Modify tunings related with
        FMA.
        * config/aarch64/tuning_models/ampere1a.h: Modify tunings related with
        FMA.
        * config/aarch64/tuning_models/ampere1b.h: Modify tunings related with
        FMA.

---
 gcc/config/aarch64/aarch64-tuning-flags.def | 2 ++
 gcc/config/aarch64/aarch64.cc               | 6 ++++++
 gcc/config/aarch64/tuning_models/ampere1.h  | 2 +-
 gcc/config/aarch64/tuning_models/ampere1a.h | 4 ++--
 gcc/config/aarch64/tuning_models/ampere1b.h | 5 +++--
 5 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-tuning-flags.def 
b/gcc/config/aarch64/aarch64-tuning-flags.def
index 774568e9106..f28a73839a6 100644
--- a/gcc/config/aarch64/aarch64-tuning-flags.def
+++ b/gcc/config/aarch64/aarch64-tuning-flags.def
@@ -47,4 +47,6 @@ AARCH64_EXTRA_TUNING_OPTION ("use_new_vector_costs", 
USE_NEW_VECTOR_COSTS)
 
 AARCH64_EXTRA_TUNING_OPTION ("matched_vector_throughput", 
MATCHED_VECTOR_THROUGHPUT)
 
+AARCH64_EXTRA_TUNING_OPTION ("avoid_cross_loop_fma", AVOID_CROSS_LOOP_FMA)
+
 #undef AARCH64_EXTRA_TUNING_OPTION
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 64684258b7b..28bc70a787f 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -16083,6 +16083,12 @@ aarch64_override_options_internal (struct gcc_options 
*opts)
       && opts->x_optimize >= aarch64_tune_params.prefetch->default_opt_level)
     opts->x_flag_prefetch_loop_arrays = 1;
 
+  /* Avoid loop-dependant FMA chains.  */
+  if (aarch64_tune_params.extra_tuning_flags
+      & AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA)
+    SET_OPTION_IF_UNSET (opts, &global_options_set, param_avoid_fma_max_bits,
+                        512);
+
   aarch64_override_options_after_change_1 (opts);
 }
 
diff --git a/gcc/config/aarch64/tuning_models/ampere1.h 
b/gcc/config/aarch64/tuning_models/ampere1.h
index 8d2a1c69610..a144e8f94b3 100644
--- a/gcc/config/aarch64/tuning_models/ampere1.h
+++ b/gcc/config/aarch64/tuning_models/ampere1.h
@@ -104,7 +104,7 @@ static const struct tune_params ampere1_tunings =
   2,   /* min_div_recip_mul_df.  */
   0,   /* max_case_values.  */
   tune_params::AUTOPREFETCHER_WEAK,    /* autoprefetcher_model.  */
-  (AARCH64_EXTRA_TUNE_NONE),   /* tune_flags.  */
+  (AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA),   /* tune_flags.  */
   &ampere1_prefetch_tune,
   AARCH64_LDP_STP_POLICY_ALIGNED,   /* ldp_policy_model.  */
   AARCH64_LDP_STP_POLICY_ALIGNED    /* stp_policy_model.  */
diff --git a/gcc/config/aarch64/tuning_models/ampere1a.h 
b/gcc/config/aarch64/tuning_models/ampere1a.h
index c419ffb3c1a..f688ed08a79 100644
--- a/gcc/config/aarch64/tuning_models/ampere1a.h
+++ b/gcc/config/aarch64/tuning_models/ampere1a.h
@@ -50,13 +50,13 @@ static const struct tune_params ampere1a_tunings =
   "32:16",     /* loop_align.  */
   2,   /* int_reassoc_width.  */
   4,   /* fp_reassoc_width.  */
-  1,   /* fma_reassoc_width.  */
+  4,   /* fma_reassoc_width.  */
   2,   /* vec_reassoc_width.  */
   2,   /* min_div_recip_mul_sf.  */
   2,   /* min_div_recip_mul_df.  */
   0,   /* max_case_values.  */
   tune_params::AUTOPREFETCHER_WEAK,    /* autoprefetcher_model.  */
-  (AARCH64_EXTRA_TUNE_NONE),   /* tune_flags.  */
+  (AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA),   /* tune_flags.  */
   &ampere1_prefetch_tune,
   AARCH64_LDP_STP_POLICY_ALIGNED,   /* ldp_policy_model.  */
   AARCH64_LDP_STP_POLICY_ALIGNED    /* stp_policy_model.  */
diff --git a/gcc/config/aarch64/tuning_models/ampere1b.h 
b/gcc/config/aarch64/tuning_models/ampere1b.h
index c4928f50d29..a98b6a980f7 100644
--- a/gcc/config/aarch64/tuning_models/ampere1b.h
+++ b/gcc/config/aarch64/tuning_models/ampere1b.h
@@ -99,13 +99,14 @@ static const struct tune_params ampere1b_tunings =
   "32:16",     /* loop_align.  */
   2,   /* int_reassoc_width.  */
   4,   /* fp_reassoc_width.  */
-  1,   /* fma_reassoc_width.  */
+  4,   /* fma_reassoc_width.  */
   2,   /* vec_reassoc_width.  */
   2,   /* min_div_recip_mul_sf.  */
   2,   /* min_div_recip_mul_df.  */
   0,   /* max_case_values.  */
   tune_params::AUTOPREFETCHER_STRONG,  /* autoprefetcher_model.  */
-  (AARCH64_EXTRA_TUNE_CHEAP_SHIFT_EXTEND),     /* tune_flags.  */
+  (AARCH64_EXTRA_TUNE_CHEAP_SHIFT_EXTEND |
+   AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA),   /* tune_flags.  */
   &ampere1b_prefetch_tune,
   AARCH64_LDP_STP_POLICY_ALIGNED,   /* ldp_policy_model.  */
   AARCH64_LDP_STP_POLICY_ALIGNED    /* stp_policy_model.  */
-- 
2.25.1