add CFLAGS_OPT_USER to make

2 files changed, 7 insertions, 1 deletions

diff --git a/common.mk b/common.mk
index 0b66caa..5f4846c 100644
--- a/common.mk
+++ b/common.mk
@@ -82,8 +82,9 @@ CFLAGS+=-g3
 INC_OPT=-I include -I test -I ../xbyak -I ../cybozulib/include
 CFLAGS+=$(CFLAGS_WARN) $(BIT_OPT) $(INC_OPT) $(CFLAGS_USER)
 DEBUG=0
+CFLAGS_OPT_USER?=$(CFLAGS_OPT)
 ifeq ($(DEBUG),0)
-CFLAGS+=$(CFLAGS_OPT)
+CFLAGS+=$(CFLAGS_OPT_USER)
 endif
 LDFLAGS+=-lgmp -lgmpxx -lcrypto $(BIT_OPT) $(LDFLAGS_USER)
 
diff --git a/readme.md b/readme.md
index 26e6ed1..ac3ee23 100644
--- a/readme.md
+++ b/readme.md
@@ -50,6 +50,11 @@ To make sample programs:
 make sample

 ```

 

+if you want to change compiler options for optimization, then set `CFLAGS_OPT_USER`.

+```

+make CLFAGS_OPT_USER="-O2"

+```

+

 ## Build for 32-bit Linux

 Build openssl and gmp for 32-bit mode and install `<lib32>`

 ```