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

diff -r acc453391c5b Makefile.pre.in
--- a/Makefile.pre.in	Sat Oct 24 17:39:36 2015 +0300
+++ b/Makefile.pre.in	Fri Oct 30 09:38:20 2015 +0200
@@ -47,6 +47,7 @@
 LLVM_PROF_MERGER=@LLVM_PROF_MERGER@
 LLVM_PROF_FILE=@LLVM_PROF_FILE@
 LLVM_PROF_ERR=@LLVM_PROF_ERR@
+LTOFLAGS=@LTOFLAGS@
 
 GNULD=          @GNULD@
 
@@ -445,7 +446,7 @@
 	$(MAKE) profile-removal
 
 build_all_generate_profile:
-	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_GEN_FLAG)" LDFLAGS="$(LDFLAGS) $(PGO_PROF_GEN_FLAG)" LIBS="$(LIBS)"
+	$(MAKE) all CFLAGS="$(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
@@ -455,7 +456,7 @@
 	$(LLVM_PROF_MERGER)
 
 build_all_use_profile:
-	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_USE_FLAG)"
+	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_USE_FLAG) $(LTOFLAGS)" LDFLAGS="$(LDFLAGS) $(LTOFLAGS)"
 
 coverage:
 	@echo "Building with support for coverage checking:"
diff -r acc453391c5b configure
--- a/configure	Sat Oct 24 17:39:36 2015 +0300
+++ b/configure	Fri Oct 30 09:38:20 2015 +0200
@@ -661,6 +661,7 @@
 SO
 LIBTOOL_CRUFT
 OTHER_LIBTOOL_OPT
+LTOFLAGS
 LLVM_PROF_FOUND
 LLVM_PROF_ERR
 LLVM_PROF_FILE
@@ -6332,8 +6333,7 @@
   CFLAGS=$save_CFLAGS
 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
@@ -6371,7 +6371,6 @@
 $as_echo "no" >&6; }
 fi
 
-
 LLVM_PROF_ERR=no
 case $CC in
   *clang*)
@@ -6380,6 +6379,7 @@
     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
@@ -6392,6 +6392,7 @@
         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 $LLVM_PROF_FOUND = not-found
         then
           LLVM_PROF_ERR=yes
@@ -6402,6 +6403,7 @@
         PGO_PROF_USE_FLAG="-fprofile-use -fprofile-correction"
         LLVM_PROF_MERGER="true"
         LLVM_PROF_FILE=""
+        LTOFLAGS="-flto -fuse-linker-plugin -ffat-lto-objects -flto-partition=none"
         ;;
     esac
     ;;
diff -r acc453391c5b configure.ac
--- a/configure.ac	Sat Oct 24 17:39:36 2015 +0300
+++ b/configure.ac	Fri Oct 30 09:38:20 2015 +0200
@@ -1352,14 +1352,14 @@
   CFLAGS=$save_CFLAGS
 fi
 
-
-# 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
@@ -1369,6 +1369,7 @@
     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
@@ -1381,6 +1382,7 @@
         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
@@ -1391,6 +1393,7 @@
         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
     ;;