# Author: Alecsandru Patrascu <alecsandru.patrascu@intel.com>

diff -r 8d2889a935b2 Makefile.pre.in
--- a/Makefile.pre.in	Thu Oct 29 08:19:59 2015 +0200
+++ b/Makefile.pre.in	Fri Oct 30 09:42:55 2015 +0200
@@ -30,7 +30,6 @@
 abs_srcdir=	@abs_srcdir@
 abs_builddir=	@abs_builddir@
 
-
 CC=		@CC@
 CXX=		@CXX@
 MAINCC=		@MAINCC@
@@ -48,6 +47,7 @@
 LLVM_PROF_MERGER=@LLVM_PROF_MERGER@
 LLVM_PROF_FILE=@LLVM_PROF_FILE@
 LLVM_PROF_ERR=@LLVM_PROF_ERR@
+LTOFLAGS=@LTOFLAGS@
 
 GNULD=		@GNULD@
 
@@ -502,7 +502,7 @@
 	$(MAKE) profile-removal
 
 build_all_generate_profile:
-	$(MAKE) all CFLAGS_NODIST="$(CFLAGS) $(PGO_PROF_GEN_FLAG)" LDFLAGS="$(LDFLAGS) $(PGO_PROF_GEN_FLAG)" LIBS="$(LIBS)"
+	$(MAKE) all CFLAGS_NODIST="$(CFLAGS) $(PGO_PROF_GEN_FLAG) $(LTOFLAGS)" LDFLAGS="$(LDFLAGS) $(PGO_PROF_GEN_FLAG) $(LTOFLAGS)" LIBS="$(LIBS)"
 
 run_profile_task:
 	: # FIXME: can't run for a cross build
@@ -512,7 +512,7 @@
 	$(LLVM_PROF_MERGER)
 
 build_all_use_profile:
-	$(MAKE) all CFLAGS_NODIST="$(CFLAGS) $(PGO_PROF_USE_FLAG)"
+	$(MAKE) all CFLAGS_NODIST="$(CFLAGS) $(PGO_PROF_USE_FLAG) $(LTOFLAGS)" LDFLAGS="$(LDFLAGS) $(LTOFLAGS)"
 
 # Compile and run with gcov
 .PHONY=coverage coverage-lcov coverage-report
diff -r 8d2889a935b2 configure
--- a/configure	Thu Oct 29 08:19:59 2015 +0200
+++ b/configure	Fri Oct 30 09:42:55 2015 +0200
@@ -667,6 +667,7 @@
 CFLAGS_NODIST
 BASECFLAGS
 OPT
+LTOFLAGS
 LLVM_PROF_FOUND
 LLVM_PROF_ERR
 LLVM_PROF_FILE
@@ -6437,7 +6438,7 @@
 fi
 
 
-# Enable PGO flags.
+# Enable PGO and LTO flags.
 # Extract the first word of "llvm-profdata", so it can be a program name with args.
 set dummy llvm-profdata; ac_word=$2
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
@@ -6475,7 +6476,6 @@
 $as_echo "no" >&6; }
 fi
 
-
 LLVM_PROF_ERR=no
 case $CC in
   *clang*)
@@ -6484,6 +6484,7 @@
     PGO_PROF_USE_FLAG="-fprofile-instr-use=code.profclangd"
     LLVM_PROF_MERGER="llvm-profdata merge -output=code.profclangd *.profclangr"
     LLVM_PROF_FILE="LLVM_PROFILE_FILE=\"code-%p.profclangr\""
+    LTOFLAGS="-flto"
     if test $LLVM_PROF_FOUND = not-found
     then
       LLVM_PROF_ERR=yes
@@ -6496,6 +6497,7 @@
         PGO_PROF_USE_FLAG="-fprofile-instr-use=code.profclangd"
         LLVM_PROF_MERGER="llvm-profdata merge -output=code.profclangd *.profclangr"
         LLVM_PROF_FILE="LLVM_PROFILE_FILE=\"code-%p.profclangr\""
+        LTOFLAGS="-flto"
         if test $LLVM_PROF_FOUND = not-found
         then
           LLVM_PROF_ERR=yes
@@ -6506,6 +6508,7 @@
         PGO_PROF_USE_FLAG="-fprofile-use -fprofile-correction"
         LLVM_PROF_MERGER="true"
         LLVM_PROF_FILE=""
+        LTOFLAGS="-flto -fuse-linker-plugin -ffat-lto-objects -flto-partition=none"
         ;;
     esac
     ;;
diff -r 8d2889a935b2 configure.ac
--- a/configure.ac	Thu Oct 29 08:19:59 2015 +0200
+++ b/configure.ac	Fri Oct 30 09:42:55 2015 +0200
@@ -1218,13 +1218,14 @@
 fi],
 [AC_MSG_RESULT(no)])
 
-# Enable PGO flags.
+# Enable PGO and LTO flags.
 AC_SUBST(PGO_PROF_GEN_FLAG)
 AC_SUBST(PGO_PROF_USE_FLAG)
 AC_SUBST(LLVM_PROF_MERGER)
 AC_SUBST(LLVM_PROF_FILE)
 AC_SUBST(LLVM_PROF_ERR)
 AC_SUBST(LLVM_PROF_FOUND)
+AC_SUBST(LTOFLAGS)
 AC_CHECK_PROG(LLVM_PROF_FOUND, llvm-profdata, found, not-found)
 LLVM_PROF_ERR=no
 case $CC in
@@ -1234,6 +1235,7 @@
     PGO_PROF_USE_FLAG="-fprofile-instr-use=code.profclangd"
     LLVM_PROF_MERGER="llvm-profdata merge -output=code.profclangd *.profclangr"
     LLVM_PROF_FILE="LLVM_PROFILE_FILE=\"code-%p.profclangr\""
+    LTOFLAGS="-flto"
     if test $LLVM_PROF_FOUND = not-found
     then
       LLVM_PROF_ERR=yes
@@ -1246,6 +1248,7 @@
         PGO_PROF_USE_FLAG="-fprofile-instr-use=code.profclangd"
         LLVM_PROF_MERGER="llvm-profdata merge -output=code.profclangd *.profclangr"
         LLVM_PROF_FILE="LLVM_PROFILE_FILE=\"code-%p.profclangr\""
+        LTOFLAGS="-flto"
         if test $LLVM_PROF_FOUND = not-found
         then
           LLVM_PROF_ERR=yes
@@ -1256,6 +1259,7 @@
         PGO_PROF_USE_FLAG="-fprofile-use -fprofile-correction"
         LLVM_PROF_MERGER="true"
         LLVM_PROF_FILE=""
+        LTOFLAGS="-flto -fuse-linker-plugin -ffat-lto-objects -flto-partition=none"
         ;;
     esac
     ;;