update readme

Makefile

@@ -39,6 +39,8 @@ OBJ_C   = $(addprefix obj/c/,$(SRC_C:.c=.o))
 OBJ_CXX = $(addprefix obj/cxx/,$(SRC_CXX:.cpp=.o))
 OBJ = $(OBJ_C) $(OBJ_CXX)
 
+# PGO stuff
+
 PGO_OBJ_C   = $(addprefix obj/pgo/c/,$(SRC_C:.c=.o))
 PGO_OBJ_CXX = $(addprefix obj/pgo/cxx/,$(SRC_CXX:.cpp=.o))
 PGO_OBJ = $(PGO_OBJ_C) $(PGO_OBJ_CXX)

README.md

@@ -71,6 +71,9 @@ To build with debug information, run `make debug`. Extra debug flags can be prov
 
 The build and unstripped binary will be `shuffle3-debug`.
 
+## PGO target
+To build with Profile Guided Optimisation run `make pgo`, the stripped and optimised binary will be output to `shuffle3-pgo`.
+
 ## Notes
 Before switching between `release` and `debug` targets, remember to run `make clean`.
 To disable stripping of release build binaries, run with `make STRIP=: release`