Add support for Verilator v5.016 (#132)

We'll only support Verilator versions older than v4.219 or newer than v5.015.

Verilator v4.225 changed the implementation for its thread pool, which affects our implementation for the in-memory snapshots LightSSS. We did not fixed the issue until v5.015. Therefore, we are currently supporting limited Verilator versions to support all features in difftest.

See verilator/verilator#3503 for more details.

src/test/csrc/verilator/emu.cpp

@@ -733,12 +733,19 @@ void Emulator::snapshot_load(const char *filename) {
 #endif
 
 void Emulator::fork_child_init() {
-#if EMU_THREAD > 1
-#if VERILATOR_VERSION_INTEGER >= 4228000
-  dut_ptr->vlSymsp->__Vm_threadPoolp = new VlThreadPool(dut_ptr->contextp(), EMU_THREAD - 1);
-#elif VERILATOR_VERSION_INTEGER >= 4210000
-  dut_ptr->vlSymsp->__Vm_threadPoolp = new VlThreadPool(dut_ptr->contextp(), EMU_THREAD - 1, 0);
+#ifdef VERILATOR_VERSION_INTEGER // >= v4.220
+#if VERILATOR_VERSION_INTEGER >= 5016000
+  // This will cause 288 bytes leaked for each one fork call.
+  // However, one million snapshots cause only 288MB leaks, which is still acceptable.
+  // See verilator/test_regress/t/t_wrapper_clone.cpp:48 to avoid leaks.
+  dut_ptr->atClone();
 #else
+#error Please use Verilator v5.016 or newer versions.
+#endif // check VERILATOR_VERSION_INTEGER values
+#elif EMU_THREADS > 1 // VERILATOR_VERSION_INTEGER not defined
+#ifdef VERILATOR_4_210 // v4.210 <= version < 4.220
+  dut_ptr->vlSymsp->__Vm_threadPoolp = new VlThreadPool(dut_ptr->contextp(), EMU_THREAD - 1, 0);
+#else // older than v4.210
   dut_ptr->__Vm_threadPoolp = new VlThreadPool(dut_ptr->contextp(), EMU_THREAD - 1, 0);
 #endif
 #endif

verilator.mk

@@ -20,7 +20,7 @@ EMU_TOP      = SimTop
 
 EMU_CSRC_DIR = $(abspath ./src/test/csrc)
 EMU_CXXFILES = $(shell find $(EMU_CSRC_DIR) -name "*.cpp") $(SIM_CXXFILES) $(DIFFTEST_CXXFILES)
-EMU_CXXFLAGS += -std=c++11 -static -Wall -I$(EMU_CSRC_DIR) -I$(SIM_CSRC_DIR) -I$(DIFFTEST_CSRC_DIR) -I$(PLUGIN_CHEAD_DIR)
+EMU_CXXFLAGS += -std=c++14 -static -Wall -I$(EMU_CSRC_DIR) -I$(SIM_CSRC_DIR) -I$(DIFFTEST_CSRC_DIR) -I$(PLUGIN_CHEAD_DIR)
 EMU_CXXFLAGS += -DVERILATOR -DNUM_CORES=$(NUM_CORES)
 EMU_CXXFLAGS += $(shell sdl2-config --cflags) -fPIE
 EMU_LDFLAGS  += -lpthread -lSDL2 -ldl -lz -lsqlite3
@@ -42,10 +42,9 @@ endif
 
 # Verilator version check
 VERILATOR_VER_CMD = verilator --version | cut -f2 -d' ' | tr -d '.'
-VERILATOR_VERSION = $(shell `$(VERILATOR_VER_CMD)`)
-
 VERILATOR_4_210 := $(shell expr `$(VERILATOR_VER_CMD)` \>= 4210)
 ifeq ($(VERILATOR_4_210),1)
+EMU_CXXFLAGS += -DVERILATOR_4_210
 VEXTRA_FLAGS += --instr-count-dpi 1
 endif
 VERILATOR_5_000 := $(shell expr `$(VERILATOR_VER_CMD)` \>= 5000)