From 493b1e3c650c35acedd3e3d9f33d23cba14e8fb9 Mon Sep 17 00:00:00 2001
From: Zeno Gantner <zenogantner@users.noreply.github.com>
Date: Tue, 19 Dec 2017 16:09:04 +0100
Subject: [PATCH] option to compile with -march=native to speed up CPU
 performance

On my laptop without GPU this gives me a significant improvement.
From about 26 seconds (9 with OpenMP) down to (still) 12 seconds (5 with OpenMP).

Intel(R) Core(TM) i5-6500T CPU @ 2.50GHz (4 cores)
gcc (Ubuntu 5.4.0-6ubuntu1~16.04.5) 5.4.0 20160609

Deactivated by default to not break e.g. distributed compilation and cross compilation.
---
 Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Makefile b/Makefile
index 5f6f6e2d..560160b2 100644
--- a/Makefile
+++ b/Makefile
@@ -2,6 +2,7 @@ GPU=0
 CUDNN=0
 OPENCV=0
 OPENMP=0
+NATIVECPU=0
 DEBUG=0
 
 ARCH= -gencode arch=compute_30,code=sm_30 \
@@ -32,6 +33,10 @@ ifeq ($(OPENMP), 1)
 CFLAGS+= -fopenmp
 endif
 
+ifeq ($(NATIVECPU), 1)
+CFLAGS+= -march=native
+endif
+
 ifeq ($(DEBUG), 1) 
 OPTS=-O0 -g
 endif