From a80fd50deaceedf05e6f2556f0a11fc8a38797bf Mon Sep 17 00:00:00 2001
From: Marcel Keller <m.keller@bristol.ac.uk>
Date: Wed, 3 Jan 2018 13:15:45 +0100
Subject: [PATCH] Support for processors without AVX.

---
 CONFIG             | 4 ++--
 README.md          | 1 +
 Tools/avx_memcpy.h | 4 ++++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/CONFIG b/CONFIG
index 2687fd7d..2f644aa9 100644
--- a/CONFIG
+++ b/CONFIG
@@ -15,7 +15,7 @@ USE_GF2N_LONG = 0
 
 # set to -march=<architecture> for optimization
 # AVX2 support (Haswell or later) changes the bit matrix transpose
-ARCH = -mtune=native
+ARCH = -mtune=native -mavx
 
 #use CONFIG.mine to overwrite DIR settings
 -include CONFIG.mine
@@ -40,7 +40,7 @@ LDLIBS += -lrt
 endif
 
 CXX = g++
-CFLAGS = $(ARCH) $(MY_CFLAGS) -g -Wextra -Wall $(OPTIM) -I$(ROOT) -pthread $(PROF) $(DEBUG) $(MOD) $(MEMPROTECT) $(GF2N_LONG) $(PREP_DIR) -maes -mpclmul -msse4.1 -mavx --std=c++11 -Werror
+CFLAGS = $(ARCH) $(MY_CFLAGS) -g -Wextra -Wall $(OPTIM) -I$(ROOT) -pthread $(PROF) $(DEBUG) $(MOD) $(MEMPROTECT) $(GF2N_LONG) $(PREP_DIR) -maes -mpclmul -msse4.1 --std=c++11 -Werror
 CPPFLAGS = $(CFLAGS)
 LD = g++
 
diff --git a/README.md b/README.md
index 288e3cd4..859f9f80 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,7 @@ In particular, the online phase will discard preprocessed data and crash when it
  - To benchmark only the online phase (skipping the secure offline phase), add the following line at the top: `MY_CFLAGS = -DINSECURE`
  - `PREP_DIR` should point to should be a local, unversioned directory to store preprocessing data (default is `Player-Data` in the current directory).
  - For the SPDZ-2 offline phase, set `USE_NTL = 1` and `MOD = -DMAX_MOD_SZ=6`.
+ - For processors without AVX (e.g., Intel Atom) or for optimization, set `ARCH = -march=<architecture>`.
 
 2) Run make (use the flag -j for faster compilation multiple threads). Remember to run `make clean` first after changing `CONFIG` or `CONFIG.mine`.
 
diff --git a/Tools/avx_memcpy.h b/Tools/avx_memcpy.h
index 1317e190..e9a2f8ff 100644
--- a/Tools/avx_memcpy.h
+++ b/Tools/avx_memcpy.h
@@ -14,11 +14,13 @@
 inline void avx_memcpy(void* dest, const void* source, size_t length)
 {
 	__m256i* d = (__m256i*)dest, *s = (__m256i*)source;
+#ifdef __AVX__
 	while (length >= 32)
 	{
 		_mm256_storeu_si256(d++, _mm256_loadu_si256(s++));
 		length -= 32;
 	}
+#endif
 	__m128i* d2 = (__m128i*)d;
 	__m128i* s2 = (__m128i*)s;
 	while (length >= 16)
@@ -33,12 +35,14 @@ inline void avx_memcpy(void* dest, const void* source, size_t length)
 inline void avx_memzero(void* dest, size_t length)
 {
 	__m256i* d = (__m256i*)dest;
+#ifdef __AVX__
 	__m256i s = _mm256_setzero_si256();
 	while (length >= 32)
 	{
 		_mm256_storeu_si256(d++, s);
 		length -= 32;
 	}
+#endif
 	if (length)
 		memset(d, 0, length);
 }