feat: support switching targets through monitor commands

include/difftest.hpp

@@ -46,6 +46,8 @@ public:
 
   bool check_all();
   int sync_regs_to_ref(void);
+  std::string list_targets(void);
+  std::string switch_target(int index);
 
   inline void halt() {
     __atomic_store_n(&halt_status, true, __ATOMIC_RELAXED);

src/difftest.cpp

@@ -1,9 +1,12 @@
 #include "api.hpp"
+#include <cerrno>
 #include <difftest.hpp>
 #include <fstream>
 #include <gdbstub.h>
 #include <spdlog/spdlog.h>
+#include <sstream>
 #include <stdexcept>
+#include <string>
 
 Difftest::Difftest(Target &&dut, std::vector<Target> &&refs) {
   this->dut = std::move(dut);
@@ -82,8 +85,12 @@ Difftest::ExecRet Difftest::exec(size_t n, gdb_action_t *ret) {
 
 gdb_action_t Difftest::stepi() {
   gdb_action_t ret = {.reason = gdb_action_t::ACT_NONE};
-  exec(1, &ret);
-  check_all();
+  ExecRet exec_result = exec(1, &ret);
+  if (exec_result.do_difftest) {
+    check_all();
+  } else {
+    sync_regs_to_ref();
+  }
   return ret;
 }
 
@@ -93,11 +100,14 @@ gdb_action_t Difftest::cont() {
   start_run();
   while (!is_halt()) {
     exec_ret = exec(1, &ret);
-    if (exec_ret.do_difftest)
-      if (check_all() == false) {
-        ret.reason = gdb_action_t::ACT_BREAKPOINT;
-        break;
-      }
+    if (exec_ret.do_difftest) {
+      check_all();
+    } else {
+      size_t pc = 0;
+      read_reg(32, &pc);
+      spdlog::debug("Difftest skipped at {}", (void *)pc);
+      sync_regs_to_ref();
+    }
     if (exec_ret.at_breakpoint)
       break;
   };
@@ -135,6 +145,32 @@ int Difftest::sync_regs_to_ref(void) {
   return ret;
 }
 
+std::string Difftest::list_targets(void) {
+  std::ostringstream os;
+  int i = 0;
+  for (auto it = this->begin(); it != this->end(); ++it, ++i) {
+    auto &target = *it;
+    os << i << ": " << target.meta.name << std::endl;
+  }
+  os << "current: " << current_target->meta.name << std::endl;
+  return os.str();
+}
+
+std::string Difftest::switch_target(int index) {
+  std::ostringstream os;
+  int i = 0;
+  for (auto it = this->begin(); it != this->end(); ++it, ++i) {
+    auto &target = *it;
+    if (i == index) {
+      current_target = &target;
+      os << "Switched to " << current_target->meta.name << std::endl;
+      return os.str();
+    }
+  }
+  os << "Invalid target target index: " << index << std::endl;
+  return os.str();
+}
+
 int Difftest::read_mem(size_t addr, size_t len, void *val) {
   return current_target->ops.read_mem(current_target->args.data(), addr, len,
                                       val);

src/gdbstub.cpp

@@ -1,3 +1,4 @@
+#include "api.hpp"
 #include <CLI/App.hpp>
 #include <CLI/Error.hpp>
 #include <cstring>
@@ -69,12 +70,19 @@ static char *gdbstub_monitor(void *args, const char *s) {
   CLI::App parser;
   std::string ret = "";
 
+  auto sync = parser.add_subcommand("sync", "Sync states between targets")
+                  ->callback([&]() { diff->sync_regs_to_ref(); });
+  parser.add_subcommand("list", "List targets.")->callback([&]() {
+    ret = diff->list_targets();
+  });
   parser.add_subcommand("help", "Print help message")->callback([&]() {
     ret = parser.help();
   });
-  auto sync = parser.add_subcommand("sync", "Sync states between targets")
-                  ->callback([&]() { diff->sync_regs_to_ref(); });
 
+  int target_index = -1;
+  parser.add_subcommand("switch", "Switch to another target")
+      ->callback([&]() { ret = diff->switch_target(target_index); })
+      ->add_option("target_index", target_index, "Index of the target");
   std::string cmdstr;
   int slen = strlen(s);
   int ch;