From d7cb6d0a3febf7893f92a84ef53c82928faeafaf Mon Sep 17 00:00:00 2001
From: Benoit Jacob <benoitjacob@google.com>
Date: Fri, 19 Jul 2019 14:12:27 -0700
Subject: [PATCH] - Disable tuning on Apple - we don't want to use an
 in-order-tuned   kernel on an Apple CPU. We shouldn't even with tuning, as
 Apple   CPUs are out-of-order, but we don't want to risk the case of  
 misdetection by the tuning nanobenchmark. - Whenever tuning is not enabled,
 have the tuning resolver just return   without even the overhead of querying
 a timestamp.

PiperOrigin-RevId: 259036253
---
 tensorflow/lite/experimental/ruy/platform.h   |  7 +++++++
 tensorflow/lite/experimental/ruy/tune.cc      | 13 ++++++-------
 tensorflow/lite/experimental/ruy/tune.h       | 13 +++++++++++++
 tensorflow/lite/experimental/ruy/tune_test.cc |  2 ++
 4 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/tensorflow/lite/experimental/ruy/platform.h b/tensorflow/lite/experimental/ruy/platform.h
index 13eccf8acf6..29c0fc20784 100644
--- a/tensorflow/lite/experimental/ruy/platform.h
+++ b/tensorflow/lite/experimental/ruy/platform.h
@@ -49,4 +49,11 @@ limitations under the License.
 #define RUY_DONOTUSEDIRECTLY_NEON_64 \
   (RUY_DONOTUSEDIRECTLY_NEON && RUY_DONOTUSEDIRECTLY_ARM_64)
 
+// Detect APPLE
+#ifdef __APPLE__
+#define RUY_DONOTUSEDIRECTLY_APPLE 1
+#else
+#define RUY_DONOTUSEDIRECTLY_APPLE 0
+#endif
+
 #endif  // TENSORFLOW_LITE_EXPERIMENTAL_RUY_PLATFORM_H_
diff --git a/tensorflow/lite/experimental/ruy/tune.cc b/tensorflow/lite/experimental/ruy/tune.cc
index d2ca263e706..58a956e03cc 100644
--- a/tensorflow/lite/experimental/ruy/tune.cc
+++ b/tensorflow/lite/experimental/ruy/tune.cc
@@ -18,13 +18,11 @@ limitations under the License.
 #include <algorithm>
 #include <cstdint>
 
-#include "tensorflow/lite/experimental/ruy/opt_set.h"
-#include "tensorflow/lite/experimental/ruy/platform.h"
 #include "tensorflow/lite/experimental/ruy/time.h"
 
 namespace ruy {
 
-#if RUY_PLATFORM(NEON_64)
+#ifdef RUY_IMPLEMENT_TUNING
 
 namespace {
 
@@ -131,7 +129,7 @@ Tuning TuningResolver::ResolveNow() {
   return is_probably_inorder ? Tuning::kInOrder : Tuning::kOutOfOrder;
 }
 
-#else  // not RUY_PLATFORM(NEON_64)
+#else  // not defined RUY_IMPLEMENT_TUNING
 
 float TuningResolver::EvalRatio() { return 0; }
 float TuningResolver::ThresholdRatio() { return 0; }
@@ -146,9 +144,7 @@ TuningResolver::TuningResolver()
     : expiry_duration_(DurationFromSeconds(kExpirySecs)) {}
 
 Tuning TuningResolver::Resolve() {
-#if !RUY_OPT_ENABLED(RUY_OPT_TUNING)
-  return Tuning::kOutOfOrder;
-#endif
+#ifdef RUY_IMPLEMENT_TUNING
   if (unresolved_tuning_ != Tuning::kAuto) {
     return unresolved_tuning_;
   }
@@ -160,6 +156,9 @@ Tuning TuningResolver::Resolve() {
   last_resolved_timepoint_ = new_timepoint;
   last_resolved_tuning_ = ResolveNow();
   return last_resolved_tuning_;
+#else
+  return Tuning::kOutOfOrder;
+#endif
 }
 
 }  // namespace ruy
diff --git a/tensorflow/lite/experimental/ruy/tune.h b/tensorflow/lite/experimental/ruy/tune.h
index c1b95842b87..a1d0eb9ae40 100644
--- a/tensorflow/lite/experimental/ruy/tune.h
+++ b/tensorflow/lite/experimental/ruy/tune.h
@@ -74,8 +74,21 @@ limitations under the License.
 
 #include <cstdint>
 
+#include "tensorflow/lite/experimental/ruy/opt_set.h"
+#include "tensorflow/lite/experimental/ruy/platform.h"
 #include "tensorflow/lite/experimental/ruy/time.h"
 
+// Tuning only implemented on NEON_64 at the moment (see assembly code
+// in the nano-benchmark) and not on Apple (some Apple CPUs produce incorrect
+// results on in-order-tuned kernels combining ARM and NEON load instructions
+// and NEON `ins` instructions).
+//
+// When tuning is not implemented, we simply always use Tuning::kOutOfOrder.
+#if RUY_OPT_ENABLED(RUY_OPT_TUNING) && RUY_PLATFORM(NEON_64) && \
+    !RUY_PLATFORM(APPLE)
+#define RUY_IMPLEMENT_TUNING
+#endif
+
 namespace ruy {
 
 enum class Tuning {
diff --git a/tensorflow/lite/experimental/ruy/tune_test.cc b/tensorflow/lite/experimental/ruy/tune_test.cc
index 571c2189e81..051c34910b6 100644
--- a/tensorflow/lite/experimental/ruy/tune_test.cc
+++ b/tensorflow/lite/experimental/ruy/tune_test.cc
@@ -33,6 +33,7 @@ TEST(TuneTest, TuneTest) {
 
   tuning_resolver.SetTuning(Tuning::kAuto);
 
+#ifdef RUY_IMPLEMENT_TUNING
   for (auto tuning : {Tuning::kOutOfOrder, Tuning::kInOrder}) {
     tuning_resolver.SetTuning(tuning);
     ASSERT_TRUE(tuning_resolver.Resolve() == tuning);
@@ -40,6 +41,7 @@ TEST(TuneTest, TuneTest) {
     std::this_thread::sleep_for(std::chrono::seconds(1));
     ASSERT_TRUE(tuning_resolver.Resolve() == tuning);
   }
+#endif
 }
 
 }  // namespace