diff --git a/Makefile b/Makefile
index 920c96ca4..739588d21 100644
--- a/Makefile
+++ b/Makefile
@@ -55,26 +55,136 @@ REMOTE ?= localhost
 .DEFAULT_GOAL = emu
 
 # simulation
+SIM_CONFIG_DIR = $(abspath ./config)
 SIM_CSRC_DIR = $(abspath ./src/test/csrc/common)
 SIM_CXXFILES = $(shell find $(SIM_CSRC_DIR) -name "*.cpp")
+SIM_CXXFLAGS = -I$(SIM_CSRC_DIR) -I$(SIM_CONFIG_DIR)
 
 # generated-src
-GEN_CSRC_DIR = $(BUILD_DIR)/generated-src
-GEN_CXXFILES = $(shell find $(GEN_CSRC_DIR) -name "*.cpp")
+GEN_CSRC_DIR  = $(BUILD_DIR)/generated-src
+SIM_CXXFILES += $(shell find $(GEN_CSRC_DIR) -name "*.cpp")
+SIM_CXXFLAGS += -I$(GEN_CSRC_DIR)
 
+PLUGIN_CSRC_DIR = $(abspath ./src/test/csrc/plugin)
+PLUGIN_INC_DIR  = $(abspath $(PLUGIN_CSRC_DIR)/include)
+SIM_CXXFLAGS   += -I$(PLUGIN_INC_DIR)
+
+VSRC_DIR   = $(abspath ./src/test/vsrc/common)
+SIM_VSRC = $(shell find $(VSRC_DIR) -name "*.v" -or -name "*.sv")
+
+# DiffTest support
 DIFFTEST_CSRC_DIR = $(abspath ./src/test/csrc/difftest)
 DIFFTEST_CXXFILES = $(shell find $(DIFFTEST_CSRC_DIR) -name "*.cpp")
+ifeq ($(NO_DIFF), 1)
+SIM_CXXFLAGS += -DCONFIG_NO_DIFFTEST
+else
+SIM_CXXFILES += $(DIFFTEST_CXXFILES)
+SIM_CXXFLAGS += -I$(DIFFTEST_CSRC_DIR)
+endif
+
+# ChiselDB
+WITH_CHISELDB ?= 1
+ifeq ($(WITH_CHISELDB), 1)
+SIM_CXXFILES += $(BUILD_DIR)/chisel_db.cpp
+SIM_CXXFLAGS += -I$(BUILD_DIR) -DENABLE_CHISEL_DB
+SIM_LDFLAGS  += -lsqlite3
+endif
+
+# ConstantIn
+WITH_CONSTANTIN ?= 1
+ifeq ($(WITH_CONSTANTIN), 1)
+SIM_CXXFILES += $(BUILD_DIR)/constantin.cpp
+SIM_CXXFLAGS += -I$(BUILD_DIR) -DENABLE_CONSTANTIN
+endif
+
+ifeq ($(WITH_IPC), 1)
+SIM_CXXFLAGS += -I$(BUILD_DIR) -DENABLE_IPC
+endif
+
+# REF SELECTION
+ifneq ($(REF),)
+ifneq ($(wildcard $(REF)),)
+SIM_CXXFLAGS += -DREF_PROXY=LinkedProxy -DLINKED_REFPROXY_LIB=\\\"$(REF)\\\"
+SIM_LDFLAGS  += $(REF)
+else
+SIM_CXXFLAGS += -DREF_PROXY=$(REF)Proxy
+REF_HOME_VAR = $(shell echo $(REF)_HOME | tr a-z A-Z)
+ifneq ($(origin $(REF_HOME_VAR)), undefined)
+SIM_CXXFLAGS += -DREF_HOME=\\\"$(shell echo $$$(REF_HOME_VAR))\\\"
+endif
+endif
+endif
+
+# co-simulation with DRAMsim3
+ifeq ($(WITH_DRAMSIM3),1)
+SIM_CXXFLAGS += -I$(DRAMSIM3_HOME)/src
+SIM_CXXFLAGS += -DWITH_DRAMSIM3 -DDRAMSIM3_CONFIG=\\\"$(DRAMSIM3_HOME)/configs/XiangShan.ini\\\" -DDRAMSIM3_OUTDIR=\\\"$(BUILD_DIR)\\\"
+SIM_LDFLAGS  += $(DRAMSIM3_HOME)/build/libdramsim3.a
+endif
 
-PLUGIN_CSRC_DIR   = $(abspath ./src/test/csrc/plugin)
-PLUGIN_INC_DIR    = $(abspath $(PLUGIN_CSRC_DIR)/include)
+ifeq ($(RELEASE),1)
+SIM_CXXFLAGS += -DBASIC_DIFFTEST_ONLY
+endif
 
-PLUGIN_DASM_DIR      = $(abspath $(PLUGIN_CSRC_DIR)/spikedasm)
-PLUGIN_DASM_CXXFILES = $(shell find $(PLUGIN_CSRC_DIR)/spikedasm -name "*.cpp")
+# VGA support
+ifeq ($(SHOW_SCREEN),1)
+SIM_CXXFLAGS += $(shell sdl2-config --cflags) -DSHOW_SCREEN
+SIM_LDFLAGS  += -lSDL2
+endif
 
-PLUGIN_RUNAHEAD_DIR      = $(abspath $(PLUGIN_CSRC_DIR)/runahead)
-PLUGIN_RUNAHEAD_CXXFILES = $(shell find $(PLUGIN_CSRC_DIR)/runahead -name "*.cpp")
+# GZ image support
+IMAGE_GZ_COMPRESS ?= 1
+ifeq ($(IMAGE_GZ_COMPRESS),0)
+SIM_CXXFLAGS += -DNO_GZ_COMPRESSION
+else
+SIM_LDFLAGS  += -lz
+endif
+
+# spike-dasm plugin
+WITH_SPIKE_DASM ?= 1
+ifeq ($(WITH_SPIKE_DASM),1)
+SIM_CXXFLAGS += -I$(abspath $(PLUGIN_CSRC_DIR)/spikedasm)
+SIM_CXXFILES += $(shell find $(PLUGIN_CSRC_DIR)/spikedasm -name "*.cpp")
+endif
 
-SIM_VSRC = $(shell find ./src/test/vsrc/common -name "*.v" -or -name "*.sv")
+# runahead support
+ifeq ($(WITH_RUNAHEAD),1)
+SIM_CXXFLAGS += -I$(abspath $(PLUGIN_CSRC_DIR)/runahead)
+SIM_CXXFILES += $(shell find $(PLUGIN_CSRC_DIR)/runahead -name "*.cpp")
+endif
+
+# Check if XFUZZ is set
+ifeq ($(XFUZZ), 1)
+XFUZZ_HOME_VAR = XFUZZ_HOME
+ifeq ($(origin $(XFUZZ_HOME_VAR)), undefined)
+$(error $(XFUZZ_HOME_VAR) is not set)
+endif
+FUZZER_LIB   = $(shell echo $$$(XFUZZ_HOME_VAR))/target/release/libfuzzer.a
+SIM_LDFLAGS += -lrt -lpthread
+endif
+
+# Link fuzzer libraries
+ifneq ($(FUZZER_LIB), )
+SIM_CXXFLAGS += -DFUZZER_LIB
+SIM_LDFLAGS  += $(abspath $(FUZZER_LIB))
+FUZZING       = 1
+endif
+
+# Fuzzer support
+ifeq ($(FUZZING),1)
+SIM_CXXFLAGS += -DFUZZING
+endif
+
+# FIRRTL Coverage support
+ifneq ($(FIRRTL_COVER),)
+SIM_CXXFLAGS += -DFIRRTL_COVER
+endif
+
+# LLVM Sanitizer Coverage support
+ifneq ($(LLVM_COVER),)
+SIM_CXXFLAGS += -DLLVM_COVER
+SIM_LDFLAGS  += -fsanitize-coverage=trace-pc-guard -fsanitize-coverage=pc-table
+endif
 
 include verilator.mk
 include vcs.mk
diff --git a/verilator.mk b/verilator.mk
index 4b7ea397d..854c36e71 100644
--- a/verilator.mk
+++ b/verilator.mk
@@ -20,58 +20,20 @@ EMU_TOP      = SimTop
 EMU_CSRC_DIR   = $(abspath ./src/test/csrc/verilator)
 EMU_CONFIG_DIR = $(abspath ./config)
 
-EMU_CXXFILES   = $(shell find $(EMU_CSRC_DIR) -name "*.cpp")
-EMU_CXXFILES  += $(SIM_CXXFILES) $(GEN_CXXFILES)
-
-EMU_CXXFLAGS += -I$(SIM_CSRC_DIR) -I$(GEN_CSRC_DIR) -I$(PLUGIN_INC_DIR)
-EMU_CXXFLAGS += -I$(EMU_CONFIG_DIR) -I$(EMU_CSRC_DIR)
+EMU_CXXFILES  = $(SIM_CXXFILES) $(shell find $(EMU_CSRC_DIR) -name "*.cpp")
+EMU_CXXFLAGS  = $(SIM_CXXFLAGS) -I$(EMU_CSRC_DIR)
 EMU_CXXFLAGS += -DVERILATOR -DNUM_CORES=$(NUM_CORES) --std=c++17
-EMU_LDFLAGS  += -ldl
+EMU_LDFLAGS   = $(SIM_LDFLAGS) -ldl
 
 # DiffTest support
-ifeq ($(NO_DIFF), 1)
-EMU_CXXFLAGS += -DCONFIG_NO_DIFFTEST
-else
-EMU_CXXFILES += $(DIFFTEST_CXXFILES)
-EMU_CXXFLAGS += -I$(DIFFTEST_CSRC_DIR)
+ifneq ($(NO_DIFF), 1)
 VEXTRA_FLAGS += +define+DIFFTEST
 endif
 
-# Check if XFUZZ is set
-ifeq ($(XFUZZ), 1)
-XFUZZ_HOME_VAR = XFUZZ_HOME
-ifeq ($(origin $(XFUZZ_HOME_VAR)), undefined)
-$(error $(XFUZZ_HOME_VAR) is not set)
-endif
-FUZZER_LIB   = $(shell echo $$$(XFUZZ_HOME_VAR))/target/release/libfuzzer.a
-EMU_LDFLAGS += -lrt -lpthread
-endif
-
 # Link fuzzer libraries
 ifneq ($(FUZZER_LIB), )
 # the target is named as fuzzer for clarity
-EMU           = $(BUILD_DIR)/fuzzer
-EMU_CXXFLAGS += -DFUZZER_LIB
-EMU_LDFLAGS  += $(abspath $(FUZZER_LIB))
-FUZZING       = 1
-endif
-
-# ChiselDB
-WITH_CHISELDB ?= 1
-ifeq ($(WITH_CHISELDB), 1)
-EMU_CXXFILES += $(BUILD_DIR)/chisel_db.cpp
-EMU_CXXFLAGS += -I$(BUILD_DIR) -DENABLE_CHISEL_DB
-EMU_LDFLAGS  += -lsqlite3
-endif
-
-WITH_CONSTANTIN ?= 1
-ifeq ($(WITH_CONSTANTIN), 1)
-EMU_CXXFILES += $(BUILD_DIR)/constantin.cpp
-EMU_CXXFLAGS += -I$(BUILD_DIR) -DENABLE_CONSTANTIN
-endif
-
-ifeq ($(WITH_IPC), 1)
-EMU_CXXFLAGS += -I$(BUILD_DIR) -DENABLE_IPC
+EMU = $(BUILD_DIR)/fuzzer
 endif
 
 # CCACHE
@@ -80,26 +42,6 @@ ifneq ($(CCACHE),)
 export OBJCACHE = ccache
 endif
 
-# REF SELECTION
-ifneq ($(REF),)
-ifneq ($(wildcard $(REF)),)
-EMU_CXXFLAGS += -DREF_PROXY=LinkedProxy -DLINKED_REFPROXY_LIB=\\\"$(REF)\\\"
-EMU_LDFLAGS  += $(REF)
-else
-EMU_CXXFLAGS += -DREF_PROXY=$(REF)Proxy
-REF_HOME_VAR = $(shell echo $(REF)_HOME | tr a-z A-Z)
-ifneq ($(origin $(REF_HOME_VAR)), undefined)
-EMU_CXXFLAGS += -DREF_HOME=\\\"$(shell echo $$$(REF_HOME_VAR))\\\"
-endif
-endif
-endif
-
-# Verilator
-USE_VERILATOR ?= 1
-ifeq ($(USE_VERILATOR),1)
-EMU_CXXFLAGS += -I$(EMU_CSRC_DIR)/verilator
-endif
-
 # Verilator version check
 VERILATOR_VER_CMD = verilator --version | cut -f2 -d' ' | tr -d '.'
 VERILATOR_4_210 := $(shell expr `$(VERILATOR_VER_CMD)` \>= 4210)
@@ -147,60 +89,6 @@ ifeq ($(EMU_COVERAGE),1)
 VEXTRA_FLAGS += --coverage-line --coverage-toggle
 endif
 
-# co-simulation with DRAMsim3
-ifeq ($(WITH_DRAMSIM3),1)
-EMU_CXXFLAGS += -I$(DRAMSIM3_HOME)/src
-EMU_CXXFLAGS += -DWITH_DRAMSIM3 -DDRAMSIM3_CONFIG=\\\"$(DRAMSIM3_HOME)/configs/XiangShan.ini\\\" -DDRAMSIM3_OUTDIR=\\\"$(BUILD_DIR)\\\"
-EMU_LDFLAGS  += $(DRAMSIM3_HOME)/build/libdramsim3.a
-endif
-
-ifeq ($(RELEASE),1)
-EMU_CXXFLAGS += -DBASIC_DIFFTEST_ONLY
-endif
-
-# VGA support
-ifeq ($(SHOW_SCREEN),1)
-EMU_CXXFLAGS += $(shell sdl2-config --cflags) -DSHOW_SCREEN
-EMU_LDFLAGS  += -lSDL2
-endif
-
-# GZ image support
-EMU_GZ_COMPRESS ?= 1
-ifeq ($(EMU_GZ_COMPRESS),0)
-EMU_CXXFLAGS += -DNO_GZ_COMPRESSION
-else
-EMU_LDFLAGS  += -lz
-endif
-
-# Verilator
-WITH_SPIKE_DASM ?= 1
-ifeq ($(WITH_SPIKE_DASM),1)
-EMU_CXXFLAGS += -I$(PLUGIN_DASM_DIR)
-EMU_CXXFILES += $(PLUGIN_DASM_CXXFILES)
-endif
-
-# runahead support
-ifeq ($(WITH_RUNAHEAD),1)
-EMU_CXXFLAGS += -I$(PLUGIN_RUNAHEAD_DIR)
-EMU_CXXFILES += $(PLUGIN_RUNAHEAD_CXXFILES)
-endif
-
-# Fuzzer support
-ifeq ($(FUZZING),1)
-EMU_CXXFLAGS += -DFUZZING
-endif
-
-# FIRRTL Coverage support
-ifneq ($(FIRRTL_COVER),)
-EMU_CXXFLAGS += -DFIRRTL_COVER
-endif
-
-# LLVM Sanitizer Coverage support
-ifneq ($(LLVM_COVER),)
-EMU_CXXFLAGS += -DLLVM_COVER
-EMU_LDFLAGS += -fsanitize-coverage=trace-pc-guard -fsanitize-coverage=pc-table
-endif
-
 VERILATOR_FLAGS =                   \
   --exe                             \
   --cc -O3 --top-module $(EMU_TOP)  \