[difftest] remove DPI C++ trampoline

difftest/online_drive/build.rs

@@ -7,17 +7,16 @@ fn main() {
   #[cfg(not(feature = "trace"))]
   let dst = Config::new("dpi_c").very_verbose(true).always_configure(true).build();
 
-  println!("cargo:rustc-link-search=native={}/lib", dst.display());
+  println!("cargo::rustc-link-search=native={}/lib", dst.display());
 
   // link order matters!
   // verilator_main <- VTestBench <-- verilated <- dpi_c <- stdc++
   // verilated <- libz
   // that's why we must split verilator_main and dpi_c
-  println!("cargo:rustc-link-lib=static=dpi_pre_link");
-  println!("cargo:rustc-link-lib=static=VTestBench");
-  println!("cargo:rustc-link-lib=static=verilated");
-  println!("cargo:rustc-link-lib=static=dpi");
-  println!("cargo:rustc-link-lib=static=stdc++");
-  println!("cargo:rustc-link-lib=dylib=z");
-  println!("cargo:rerun-if-env-changed=VERILATED_LIB_DIR");
+  println!("cargo::rustc-link-lib=static=dpi_pre_link");
+  println!("cargo::rustc-link-lib=static=VTestBench");
+  println!("cargo::rustc-link-lib=static=verilated");
+  println!("cargo::rustc-link-lib=stdc++");
+  println!("cargo::rustc-link-lib=z");
+  println!("cargo::rerun-if-env-changed=VERILATED_LIB_DIR");
 }

difftest/online_drive/dpi_c/CMakeLists.txt

@@ -6,11 +6,6 @@ message(STATUS "Project '${PROJECT_NAME}' build type: ${CMAKE_BUILD_TYPE}")
 
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 
-add_library(dpi
-  STATIC
-  dpi.cc
-)
-
 add_library(dpi_pre_link
   STATIC
   dpi_pre_link.cc
@@ -30,21 +25,14 @@ if (NOT DEFINED VERILATED_INC_DIR)
   endif()
 endif()
 
-# include verilated headers
-target_include_directories(dpi PUBLIC ${VERILATED_INC_DIR})
-target_include_directories(dpi PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
-
 # include verilator headers
 find_package(verilator REQUIRED)
 message(STATUS "Found verilator: ${verilator_DIR}")
-target_include_directories(dpi PUBLIC ${verilator_DIR}/include)
-target_include_directories(dpi PUBLIC ${verilator_DIR}/include/vltstd)
 target_include_directories(dpi_pre_link PUBLIC ${verilator_DIR}/include)
 target_include_directories(dpi_pre_link PUBLIC ${verilator_DIR}/include/vltstd)
 
 if(DEFINED VM_TRACE)
-  target_compile_definitions(dpi PRIVATE VM_TRACE=1)
   target_compile_definitions(dpi_pre_link PRIVATE VM_TRACE=1)
 endif()
 
-install(TARGETS dpi dpi_pre_link ARCHIVE)
+install(TARGETS dpi_pre_link ARCHIVE)

difftest/online_drive/dpi_c/dpi_pre_link.cc

@@ -1,19 +1,20 @@
 #include <VTestBench.h>
 #include <VTestBench__Dpi.h>
 
-#include "dpi_pre_link.h"
-
 class VTestBench;
 
-VerilatedContext *contextp;
-VTestBench *topp;
+static VerilatedContext *contextp;
+static VTestBench *topp;
 
-int verilator_main_c(int argc, char **argv) {
+extern "C" int verilator_main_c(int argc, char **argv) {
   // Setup context, defaults, and parse command line
   Verilated::debug(0);
   contextp = new VerilatedContext();
   contextp->fatalOnError(false);
   contextp->commandArgs(argc, argv);
+#ifdef VM_TRACE
+  contextp->traceEverOn(true);
+#endif
 
   // Construct the Verilated model, from Vtop.h generated from Verilating
   topp = new VTestBench(contextp);
@@ -42,14 +43,13 @@ int verilator_main_c(int argc, char **argv) {
 }
 
 #ifdef VM_TRACE
-void dump_wave_c(char *path) {
-  Verilated::traceEverOn(true);
+extern "C" void dump_wave_c(char *path) {
   svSetScope(svGetScopeFromName("TOP.TestBench.clockGen"));
   dump_wave(path);
 }
 #endif
 
-uint64_t get_t_c() {
+extern "C" uint64_t get_t_c() {
   if (contextp) {
     return contextp->time();
   } else { // before ctx is initialized