Add benchmark

bench/Makefile

@@ -0,0 +1,28 @@
+CC=riscv64-linux-gnu-gcc-10
+CXX=riscv64-linux-gnu-g++-10
+KECC=../target/release/kecc
+CFLAGS=-O
+RM=rm -f
+
+SRCS=$(shell find . -name "*.c")
+OBJS=$(subst .c,.s,$(SRCS))
+
+all: bench
+
+bench: $(OBJS) driver.o
+	$(CXX) -o bench $(OBJS) driver.o
+
+run: bench
+	qemu-riscv64-static -L /usr/riscv64-linux-gnu ./bench
+
+driver.o: driver.cpp
+	$(CXX) $(CFLAGS) -o driver.o -c -I. driver.cpp
+
+.c.s:
+	($(KECC) -O $< >$@) || (rm $@ -rf; exit 1)
+
+$(KECC):
+	cargo build --manifest-path=../Cargo.toml --release --bin kecc
+
+clean:
+	$(RM) $(OBJS) driver.o bench