From c7b960e72cf7a98506bae57a23aca3b8af44eb23 Mon Sep 17 00:00:00 2001
From: Moinak Ghosh <moinakg@gmail.com>
Date: Tue, 11 Dec 2012 17:58:23 +0530
Subject: [PATCH] Enable use of Link Time Optimizations in GCC.

---
 Makefile.in | 6 +++---
 config      | 7 +++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/Makefile.in b/Makefile.in
index 19441e4..9a15e44 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -147,9 +147,9 @@ DEBUG_RABIN_OPT = -O -fno-omit-frame-pointer
 DEBUG_CPPFLAGS = $(COMMON_CPPFLAGS)
 DEBUG_FPTR_FLAG = 
 
-RELEASE_LINK = g++ -m64 -pthread -msse3 @LIBBSCGEN_OPT@
-RELEASE_COMPILE = gcc -m64 -msse3 -c
-RELEASE_COMPILE_cpp = g++ -m64 -msse3 -c
+RELEASE_LINK = g++ -m64 -pthread -msse3 @LIBBSCGEN_OPT@ @LTO_FLAG@
+RELEASE_COMPILE = gcc -m64 -msse3 -c @LTO_FLAG@
+RELEASE_COMPILE_cpp = g++ -m64 -msse3 -c @LTO_FLAG@
 RELEASE_VEC_FLAGS = $(COMMON_VEC_FLAGS)
 RELEASE_LOOP_OPTFLAGS = $(COMMON_LOOP_OPTFLAGS)
 RELEASE_CPPFLAGS = $(COMMON_CPPFLAGS) -DNDEBUG
diff --git a/config b/config
index 5ece5a5..87225f5 100755
--- a/config
+++ b/config
@@ -46,6 +46,7 @@ yasm=yasm
 keccak_srcs=
 keccak_hdrs=
 keccak_srcs_asm=
+lto_flag=
 
 # Try a simple compilation
 cat << _EOF > tst.c
@@ -71,6 +72,10 @@ then
 	exit 1
 fi
 
+# Check GCC version and enable LTO flags if possible
+gcc -v 2>&1 | grep lto > /dev/null
+[ $? -eq 0 ] && lto_flag="-flto"
+
 # Check bitness of system
 bitness=`./tst`
 rm -f tst tst.c
@@ -344,6 +349,7 @@ sha256asmobjsvar="SHA256ASM_OBJS"
 sha256objsvar="SHA256_OBJS"
 yasmvar="YASM"
 fptr_flag_var="FPTR_FLAG"
+lto_flag_var="LTO_FLAG"
 
 openssllibdirvar="OPENSSL_LIBDIR"
 opensslincdirvar="OPENSSL_INCDIR"
@@ -396,5 +402,6 @@ s#@${keccak_srcs_var}@#${keccak_srcs}#g
 s#@${keccak_hdrs_var}@#${keccak_hdrs}#g
 s#@${keccak_srcs_var}@#${keccak_srcs}#g
 s#@${keccak_srcs_asm_var}@#${keccak_srcs_asm}#g
+s#@${lto_flag_var}@#${lto_flag}#g
 " > Makefile