diff --git a/Makefile b/Makefile
index e8a49880..dff17c6b 100644
--- a/Makefile
+++ b/Makefile
@@ -25,14 +25,15 @@ ifeq ("$(ARCHTYPE)", "")
 endif
 
 CC1_ARCH_DIR:=$(CC1_DIR)/arch/$(ARCHTYPE)
+CC1_FE_DIR:=$(CC1_DIR)/frontend
+CC1_BE_DIR:=$(CC1_DIR)/backend
 
 OPTIMIZE:=-O2 -g3
 CFLAGS:=-ansi -std=c11 -pedantic -MMD -Wall -Wextra -Werror -Wold-style-definition \
 	-Wno-missing-field-initializers -Wno-typedef-redefinition -Wno-empty-body \
 	-Wno-gnu-zero-variadic-macro-arguments \
 	-D_DEFAULT_SOURCE $(OPTIMIZE) \
-	-I$(CC1_DIR) -I$(AS_DIR) -I$(UTIL_DIR) \
-	-I$(CC1_ARCH_DIR)
+	-I$(CC1_FE_DIR) -I$(CC1_BE_DIR) -I$(CC1_ARCH_DIR) -I$(AS_DIR) -I$(UTIL_DIR)
 ifneq ("$(NO_FLONUM)","")
 CFLAGS+=-D__NO_FLONUM
 endif
@@ -56,7 +57,7 @@ EXES:=xcc cc1 cpp as ld
 
 xcc_SRCS:=$(wildcard $(XCC_DIR)/*.c) \
 	$(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
-cc1_SRCS:=$(wildcard $(CC1_DIR)/*.c) \
+cc1_SRCS:=$(wildcard $(CC1_FE_DIR)/*.c) $(wildcard $(CC1_BE_DIR)/*.c) $(wildcard $(CC1_DIR)/*.c) \
 	$(wildcard $(CC1_ARCH_DIR)/*.c) \
 	$(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 cpp_SRCS:=$(wildcard $(CPP_DIR)/*.c) \
@@ -96,8 +97,8 @@ $(OBJ_DIR)/%.o: $(1)/%.c $(PARENT_DEPS)
 	@mkdir -p $(OBJ_DIR)
 	$(CC) $(CFLAGS) -c -o $$@ $$<
 endef
-XCC_SRC_DIRS:=$(XCC_DIR) $(CC1_DIR) $(CC1_ARCH_DIR) $(CPP_DIR) $(AS_DIR) $(LD_DIR) $(UTIL_DIR) \
-	$(DEBUG_DIR)
+XCC_SRC_DIRS:=$(XCC_DIR) $(CC1_FE_DIR) $(CC1_BE_DIR) $(CC1_DIR) $(CC1_ARCH_DIR) $(CPP_DIR) \
+	$(AS_DIR) $(LD_DIR) $(UTIL_DIR) $(DEBUG_DIR)
 $(foreach D, $(XCC_SRC_DIRS), $(eval $(call DEFINE_OBJ_TARGET,$(D))))
 
 .PHONY: test
@@ -168,9 +169,9 @@ WCC_DIR:=src/wcc
 WCC_CFLAGS:=$(CFLAGS) -I$(CPP_DIR) -DTARGET_WASM
 
 WCC_SRCS:=$(wildcard $(WCC_DIR)/*.c) \
-	$(CC1_DIR)/lexer.c $(CC1_DIR)/type.c $(CC1_DIR)/var.c $(CC1_DIR)/ast.c $(CC1_DIR)/parser.c \
-	$(CC1_DIR)/parser_expr.c $(CPP_DIR)/preprocessor.c $(CPP_DIR)/pp_parser.c $(CPP_DIR)/macro.c \
-	$(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
+	$(CC1_FE_DIR)/lexer.c $(CC1_FE_DIR)/type.c $(CC1_FE_DIR)/var.c $(CC1_FE_DIR)/ast.c \
+	$(CC1_FE_DIR)/parser.c $(CC1_FE_DIR)/parser_expr.c $(CPP_DIR)/preprocessor.c \
+	$(CPP_DIR)/pp_parser.c $(CPP_DIR)/macro.c $(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 WCC_OBJS:=$(addprefix $(WCC_OBJ_DIR)/,$(notdir $(WCC_SRCS:.c=.o)))
 WCC_LIBS:=$(LIBSRC_DIR)/_wasm/crt0.c $(LIBSRC_DIR)/_wasm/libc.c
 
@@ -182,7 +183,7 @@ $(WCC_OBJ_DIR)/%.o: $(1)/%.c $(PARENT_DEPS)
 	@mkdir -p $(WCC_OBJ_DIR)
 	$(CC) $(WCC_CFLAGS) -c -o $$@ $$<
 endef
-WCC_SRC_DIRS:=$(WCC_DIR) $(CC1_DIR) $(CPP_DIR) $(UTIL_DIR)
+WCC_SRC_DIRS:=$(WCC_DIR) $(CC1_FE_DIR) $(CC1_BE_DIR) $(CC1_DIR) $(CPP_DIR) $(UTIL_DIR)
 $(foreach D, $(WCC_SRC_DIRS), $(eval $(call DEFINE_WCCOBJ_TARGET,$(D))))
 
 WCC_CRT0_SRCS:=$(wildcard $(LIBSRC_DIR)/_wasm/crt0/*.c)
@@ -243,7 +244,7 @@ test-wcc-self-hosting:
 
 $(WCC_TARGET)cc.wasm:	$(WCC_SRCS) $(WCC_LIBS) $(WCC_PARENT)
 	$(HOST_WCC) -o $@ \
-		-I$(CC1_DIR) -I$(CPP_DIR) -I$(UTIL_DIR) \
+		-I$(CC1_FE_DIR) -I$(CPP_DIR) -I$(UTIL_DIR) \
 		$(WCC_SRCS)
 
 #### www
@@ -274,20 +275,20 @@ release-wcc:	assets
 DEBUG_EXES:=dump_expr dump_ir dump_type
 DEBUG_CFLAGS:=$(subst -MMD,,$(CFLAGS))
 
-dump_expr_SRCS:=$(DEBUG_DIR)/dump_expr.c $(CC1_DIR)/parser_expr.c $(CC1_DIR)/parser.c \
-	$(CC1_DIR)/lexer.c $(CC1_DIR)/type.c $(CC1_DIR)/ast.c $(CC1_DIR)/var.c \
+dump_expr_SRCS:=$(DEBUG_DIR)/dump_expr.c $(CC1_FE_DIR)/parser_expr.c $(CC1_FE_DIR)/parser.c \
+	$(CC1_FE_DIR)/lexer.c $(CC1_FE_DIR)/type.c $(CC1_FE_DIR)/ast.c $(CC1_FE_DIR)/var.c \
 	$(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 dump_expr_OBJS:=$(addprefix $(OBJ_DIR)/,$(notdir $(dump_expr_SRCS:.c=.o)))
 
-dump_ir_SRCS:=$(DEBUG_DIR)/dump_ir.c $(CC1_DIR)/parser_expr.c $(CC1_DIR)/parser.c \
-	$(CC1_DIR)/lexer.c $(CC1_DIR)/type.c $(CC1_DIR)/ast.c $(CC1_DIR)/var.c $(CC1_DIR)/builtin.c \
-	$(CC1_DIR)/codegen_expr.c $(CC1_DIR)/codegen.c $(CC1_DIR)/ir.c $(CC1_DIR)/regalloc.c \
-	$(CC1_ARCH_DIR)/emit_code.c $(CC1_DIR)/emit_util.c $(CC1_ARCH_DIR)/ir_$(ARCHTYPE).c \
-	$(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
+dump_ir_SRCS:=$(DEBUG_DIR)/dump_ir.c $(CC1_FE_DIR)/parser_expr.c $(CC1_FE_DIR)/parser.c \
+	$(CC1_FE_DIR)/lexer.c $(CC1_FE_DIR)/type.c $(CC1_FE_DIR)/ast.c $(CC1_FE_DIR)/var.c \
+	$(CC1_BE_DIR)/codegen_expr.c $(CC1_BE_DIR)/codegen.c $(CC1_BE_DIR)/ir.c \
+	$(CC1_BE_DIR)/regalloc.c $(CC1_BE_DIR)/emit_util.c $(CC1_ARCH_DIR)/emit_code.c \
+	 $(CC1_ARCH_DIR)/ir_$(ARCHTYPE).c $(CC1_DIR)/builtin.c $(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 dump_ir_OBJS:=$(addprefix $(OBJ_DIR)/,$(notdir $(dump_ir_SRCS:.c=.o)))
 
-dump_type_SRCS:=$(DEBUG_DIR)/dump_type.c $(CC1_DIR)/parser_expr.c $(CC1_DIR)/parser.c \
-	$(CC1_DIR)/lexer.c $(CC1_DIR)/type.c $(CC1_DIR)/ast.c $(CC1_DIR)/var.c \
+dump_typ_SRCS:=$(DEBUG_DIR)/dump_type.c $(CC1_FE_DIR)/parser_expr.c $(CC1_FE_DIR)/parser.c \
+	$(CC1_FE_DIR)/lexer.c $(CC1_FE_DIR)/type.c $(CC1_FE_DIR)/ast.c $(CC1_FE_DIR)/var.c \
 	$(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 dump_type_OBJS:=$(addprefix $(OBJ_DIR)/,$(notdir $(dump_type_SRCS:.c=.o)))
 
diff --git a/compile_flags.txt b/compile_flags.txt
index ad6c8492..428209e8 100644
--- a/compile_flags.txt
+++ b/compile_flags.txt
@@ -1,3 +1,4 @@
 -I./src/as
--I./src/cc
+-I./src/cc/backend
+-I./src/cc/frontend
 -I./src/util
diff --git a/src/cc/codegen.c b/src/cc/backend/codegen.c
similarity index 99%
rename from src/cc/codegen.c
rename to src/cc/backend/codegen.c
index e223b70f..1cecdd89 100644
--- a/src/cc/codegen.c
+++ b/src/cc/backend/codegen.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "codegen.h"
 
 #include <assert.h>
diff --git a/src/cc/codegen.h b/src/cc/backend/codegen.h
similarity index 100%
rename from src/cc/codegen.h
rename to src/cc/backend/codegen.h
diff --git a/src/cc/codegen_expr.c b/src/cc/backend/codegen_expr.c
similarity index 99%
rename from src/cc/codegen_expr.c
rename to src/cc/backend/codegen_expr.c
index 24b03408..40a916dc 100644
--- a/src/cc/codegen_expr.c
+++ b/src/cc/backend/codegen_expr.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "codegen.h"
 
 #include <assert.h>
diff --git a/src/cc/emit_util.c b/src/cc/backend/emit_util.c
similarity index 99%
rename from src/cc/emit_util.c
rename to src/cc/backend/emit_util.c
index ee4145e4..388fab16 100644
--- a/src/cc/emit_util.c
+++ b/src/cc/backend/emit_util.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "emit_util.h"
 
 #include <assert.h>
diff --git a/src/cc/emit_util.h b/src/cc/backend/emit_util.h
similarity index 100%
rename from src/cc/emit_util.h
rename to src/cc/backend/emit_util.h
diff --git a/src/cc/ir.c b/src/cc/backend/ir.c
similarity index 99%
rename from src/cc/ir.c
rename to src/cc/backend/ir.c
index c78a98fd..a72bc02a 100644
--- a/src/cc/ir.c
+++ b/src/cc/backend/ir.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "ir.h"
 
 #include <assert.h>
diff --git a/src/cc/ir.h b/src/cc/backend/ir.h
similarity index 100%
rename from src/cc/ir.h
rename to src/cc/backend/ir.h
diff --git a/src/cc/regalloc.c b/src/cc/backend/regalloc.c
similarity index 99%
rename from src/cc/regalloc.c
rename to src/cc/backend/regalloc.c
index 64cdde28..55fabc2a 100644
--- a/src/cc/regalloc.c
+++ b/src/cc/backend/regalloc.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "regalloc.h"
 
 #include <assert.h>
diff --git a/src/cc/regalloc.h b/src/cc/backend/regalloc.h
similarity index 100%
rename from src/cc/regalloc.h
rename to src/cc/backend/regalloc.h
diff --git a/src/cc/ast.c b/src/cc/frontend/ast.c
similarity index 99%
rename from src/cc/ast.c
rename to src/cc/frontend/ast.c
index 0471f3ac..9c11f161 100644
--- a/src/cc/ast.c
+++ b/src/cc/frontend/ast.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "ast.h"
 
 #include <assert.h>
diff --git a/src/cc/ast.h b/src/cc/frontend/ast.h
similarity index 100%
rename from src/cc/ast.h
rename to src/cc/frontend/ast.h
diff --git a/src/cc/lexer.c b/src/cc/frontend/lexer.c
similarity index 99%
rename from src/cc/lexer.c
rename to src/cc/frontend/lexer.c
index 916cc80e..ed14389b 100644
--- a/src/cc/lexer.c
+++ b/src/cc/frontend/lexer.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "lexer.h"
 
 #include <assert.h>
diff --git a/src/cc/lexer.h b/src/cc/frontend/lexer.h
similarity index 100%
rename from src/cc/lexer.h
rename to src/cc/frontend/lexer.h
diff --git a/src/cc/parser.c b/src/cc/frontend/parser.c
similarity index 99%
rename from src/cc/parser.c
rename to src/cc/frontend/parser.c
index 277dc211..2e31b937 100644
--- a/src/cc/parser.c
+++ b/src/cc/frontend/parser.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "parser.h"
 
 #include <assert.h>
diff --git a/src/cc/parser.h b/src/cc/frontend/parser.h
similarity index 100%
rename from src/cc/parser.h
rename to src/cc/frontend/parser.h
diff --git a/src/cc/parser_expr.c b/src/cc/frontend/parser_expr.c
similarity index 99%
rename from src/cc/parser_expr.c
rename to src/cc/frontend/parser_expr.c
index 35e4c5f9..2f7b31fd 100644
--- a/src/cc/parser_expr.c
+++ b/src/cc/frontend/parser_expr.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "parser.h"
 
 #include <assert.h>
diff --git a/src/cc/type.c b/src/cc/frontend/type.c
similarity index 99%
rename from src/cc/type.c
rename to src/cc/frontend/type.c
index 3eafba21..356420e6 100644
--- a/src/cc/type.c
+++ b/src/cc/frontend/type.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "type.h"
 
 #include <assert.h>
diff --git a/src/cc/type.h b/src/cc/frontend/type.h
similarity index 100%
rename from src/cc/type.h
rename to src/cc/frontend/type.h
diff --git a/src/cc/var.c b/src/cc/frontend/var.c
similarity index 99%
rename from src/cc/var.c
rename to src/cc/frontend/var.c
index dbbd6f8a..9d1c7de0 100644
--- a/src/cc/var.c
+++ b/src/cc/frontend/var.c
@@ -1,4 +1,4 @@
-#include "../config.h"
+#include "../../config.h"
 #include "var.h"
 
 #include <assert.h>
diff --git a/src/cc/var.h b/src/cc/frontend/var.h
similarity index 100%
rename from src/cc/var.h
rename to src/cc/frontend/var.h
diff --git a/tests/Makefile b/tests/Makefile
index 1d096a47..34b3a465 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -1,13 +1,16 @@
 ROOT_DIR:=..
 SRC_DIR:=$(ROOT_DIR)/src
-CC_DIR:=$(SRC_DIR)/cc
+CC1_DIR:=$(SRC_DIR)/cc
 UTIL_DIR:=$(SRC_DIR)/util
 DEBUG_DIR:=$(SRC_DIR)/_debug
 
+CC1_FE_DIR:=$(CC1_DIR)/frontend
+CC1_BE_DIR:=$(CC1_DIR)/backend
+
 CFLAGS:=-ansi -std=c11 -Wall -Wextra -Werror \
 	-Wold-style-definition -Wno-missing-field-initializers -Wno-typedef-redefinition \
 	-Wno-empty-body
-CFLAGS+=-I$(CC_DIR) -I$(UTIL_DIR)
+CFLAGS+=-I$(CC1_FE_DIR) -I$(UTIL_DIR)
 CFLAGS+=-D_POSIX_C_SOURCE=200809L  # for getline
 
 PREFIX:=
@@ -99,8 +102,8 @@ test-link: link_test # $(XCC)
 	@echo '## Link test'
 	@./link_test
 
-INITIALIZER_SRCS:=initializer_test.c $(CC_DIR)/parser.c $(CC_DIR)/parser_expr.c $(CC_DIR)/lexer.c \
-	$(CC_DIR)/var.c $(CC_DIR)/type.c $(CC_DIR)/ast.c $(UTIL_DIR)/util.c $(UTIL_DIR)/table.c \
+INITIALIZER_SRCS:=initializer_test.c $(CC1_FE_DIR)/parser.c $(CC1_FE_DIR)/parser_expr.c $(CC1_FE_DIR)/lexer.c \
+	$(CC1_FE_DIR)/var.c $(CC1_FE_DIR)/type.c $(CC1_FE_DIR)/ast.c $(UTIL_DIR)/util.c $(UTIL_DIR)/table.c \
 	$(DEBUG_DIR)/dump_expr.c
 initializer_test:	$(INITIALIZER_SRCS)
 	$(CC) -o$@ -DNO_MAIN_DUMP_EXPR $(CFLAGS) $^
@@ -113,8 +116,8 @@ UTIL_SRCS:=util_test.c $(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 util_test:	$(UTIL_SRCS)
 	$(CC) -o$@ $(CFLAGS) $^
 
-PARSER_SRCS:=parser_test.c $(CC_DIR)/parser_expr.c $(CC_DIR)/lexer.c $(CC_DIR)/parser.c \
-	$(CC_DIR)/type.c $(CC_DIR)/ast.c $(CC_DIR)/var.c \
+PARSER_SRCS:=parser_test.c $(CC1_FE_DIR)/parser_expr.c $(CC1_FE_DIR)/lexer.c $(CC1_FE_DIR)/parser.c \
+	$(CC1_FE_DIR)/type.c $(CC1_FE_DIR)/ast.c $(CC1_FE_DIR)/var.c \
 	$(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 parser_test:	$(PARSER_SRCS)
 	$(CC) -o$@ $(CFLAGS) $^
@@ -129,7 +132,7 @@ dvaltest:	$(FVAL_SRCS) flotest.inc # $(XCC)
 fvaltest:	$(FVAL_SRCS) flotest.inc # $(XCC)
 	$(XCC) -o$@ -Werror -DUSE_SINGLE $(FVAL_SRCS)
 
-TYPE_SRCS:=print_type_test.c $(CC_DIR)/type.c $(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
+TYPE_SRCS:=print_type_test.c $(CC1_FE_DIR)/type.c $(UTIL_DIR)/util.c $(UTIL_DIR)/table.c
 print_type_test:	$(TYPE_SRCS)
 	$(CC) -o $@ $(CFLAGS) $^