From d747d2a0c3d0afeadd6d287d2dd0158dc470a368 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers3@gmail.com>
Date: Fri, 4 Dec 2015 01:07:22 -0600
Subject: [PATCH] Add ARM NEON support

---
 src/matchfinder_common.h | 18 ++++++++++++
 src/matchfinder_neon.h   | 61 ++++++++++++++++++++++++++++++++++++++++
 tools/android_test.sh    |  2 +-
 3 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 src/matchfinder_neon.h

diff --git a/src/matchfinder_common.h b/src/matchfinder_common.h
index 2858d5a..2d7ffd9 100644
--- a/src/matchfinder_common.h
+++ b/src/matchfinder_common.h
@@ -36,6 +36,14 @@ typedef s16 mf_pos_t;
 #  endif
 #endif
 
+#ifdef __ARM_NEON__
+#  include "matchfinder_neon.h"
+#  if MATCHFINDER_ALIGNMENT < 16
+#    undef MATCHFINDER_ALIGNMENT
+#    define MATCHFINDER_ALIGNMENT 16
+#  endif
+#endif
+
 /*
  * Initialize the hash table portion of the matchfinder.
  *
@@ -58,6 +66,11 @@ matchfinder_init(mf_pos_t *data, size_t num_entries)
 		return;
 #endif
 
+#if defined(__ARM_NEON__) && defined(_aligned_attribute)
+	if (matchfinder_init_neon(data, size))
+		return;
+#endif
+
 	for (size_t i = 0; i < num_entries; i++)
 		data[i] = MATCHFINDER_INITVAL;
 }
@@ -98,6 +111,11 @@ matchfinder_rebase(mf_pos_t *data, size_t num_entries)
 		return;
 #endif
 
+#if defined(__ARM_NEON__) && defined(_aligned_attribute)
+	if (matchfinder_rebase_neon(data, size))
+		return;
+#endif
+
 	if (MATCHFINDER_WINDOW_SIZE == 32768) {
 		/* Branchless version for 32768 byte windows.  If the value was
 		 * already negative, clear all bits except the sign bit; this
diff --git a/src/matchfinder_neon.h b/src/matchfinder_neon.h
new file mode 100644
index 0000000..42ec662
--- /dev/null
+++ b/src/matchfinder_neon.h
@@ -0,0 +1,61 @@
+/*
+ * matchfinder_neon.h - matchfinding routines optimized for ARM NEON (Advanced
+ * SIMD) instructions
+ */
+
+#include <arm_neon.h>
+
+static forceinline bool
+matchfinder_init_neon(mf_pos_t *data, size_t size)
+{
+	int16x8_t v, *p;
+	size_t n;
+
+	if (size % sizeof(int16x8_t) * 4)
+		return false;
+
+	STATIC_ASSERT(sizeof(mf_pos_t) == 2);
+	v = (int16x8_t) {
+		MATCHFINDER_INITVAL, MATCHFINDER_INITVAL, MATCHFINDER_INITVAL,
+		MATCHFINDER_INITVAL, MATCHFINDER_INITVAL, MATCHFINDER_INITVAL,
+		MATCHFINDER_INITVAL, MATCHFINDER_INITVAL,
+	};
+	p = (int16x8_t *)data;
+	n = size / (sizeof(int16x8_t) * 4);
+	do {
+		p[0] = v;
+		p[1] = v;
+		p[2] = v;
+		p[3] = v;
+		p += 4;
+	} while (--n);
+	return true;
+}
+
+static forceinline bool
+matchfinder_rebase_neon(mf_pos_t *data, size_t size)
+{
+	int16x8_t v, *p;
+	size_t n;
+
+	if ((size % sizeof(int16x8_t) * 4 != 0))
+		return false;
+
+	STATIC_ASSERT(sizeof(mf_pos_t) == 2);
+	v = (int16x8_t) {
+		(u16)-MATCHFINDER_WINDOW_SIZE, (u16)-MATCHFINDER_WINDOW_SIZE,
+		(u16)-MATCHFINDER_WINDOW_SIZE, (u16)-MATCHFINDER_WINDOW_SIZE,
+		(u16)-MATCHFINDER_WINDOW_SIZE, (u16)-MATCHFINDER_WINDOW_SIZE,
+		(u16)-MATCHFINDER_WINDOW_SIZE, (u16)-MATCHFINDER_WINDOW_SIZE,
+	};
+	p = (int16x8_t *)data;
+	n = size / (sizeof(int16x8_t) * 4);
+	do {
+		p[0] = vqaddq_s16(p[0], v);
+		p[1] = vqaddq_s16(p[1], v);
+		p[2] = vqaddq_s16(p[2], v);
+		p[3] = vqaddq_s16(p[3], v);
+		p += 4;
+	} while (--n);
+	return true;
+}
diff --git a/tools/android_test.sh b/tools/android_test.sh
index fd73cb2..1414221 100755
--- a/tools/android_test.sh
+++ b/tools/android_test.sh
@@ -7,7 +7,7 @@ NDKDIR=/opt/android-ndk
 make clean
 make -j4 BUILD_SHARED_LIBRARY=no BUILD_BENCHMARK_PROGRAM=yes \
 	CC="$NDKDIR/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-gcc" \
-	CFLAGS="--sysroot=$NDKDIR/platforms/android-12/arch-arm -march=armv7-a"
+	CFLAGS="--sysroot=$NDKDIR/platforms/android-12/arch-arm -march=armv7-a -fPIC -pie -mfpu=neon -mfloat-abi=softfp"
 
 adb push benchmark /data/local/tmp
 adb shell /data/local/tmp/benchmark /data/local/tmp/testdata "$@"