A64: Fix 'step instruction' ('si') in debugger

src/a64/simulator-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2728 matching lines @@
       // Use sscanf to parse the individual parts of the command line. At the
       // moment no command expects more than two parameters.
       int argc = SScanF(line,
                         "%" XSTR(COMMAND_SIZE) "s "
                         "%" XSTR(ARG_SIZE) "s "
                         "%" XSTR(ARG_SIZE) "s",
                         cmd, arg1, arg2);
 
       // stepi / si ------------------------------------------------------------
       if ((strcmp(cmd, "si") == 0) || (strcmp(cmd, "stepi") == 0)) {
-        int64_t number_of_instructions_to_execute = 1;
-        if (argc >= 2) {
+        // We are about to execute instructions, after which by default we
+        // should increment the pc_. If it was set when reaching this debug
+        // instruction, it has not been cleared because this instruction has not
+        // completed yet. So clear it manually.
+        pc_modified_ = false;
+
+        if (argc == 1) {
+          ExecuteInstruction();
+        } else {
+          int64_t number_of_instructions_to_execute = 1;
           GetValue(arg1, &number_of_instructions_to_execute);
+
+          set_log_parameters(log_parameters() | LOG_DISASM);
+          while (number_of_instructions_to_execute-- > 0) {
+            ExecuteInstruction();
+          }
+          set_log_parameters(log_parameters() & ~LOG_DISASM);
+          PrintF("\n");
         }
-        // Prevent from printing the next instruction twice.
-        if (log_parameters_ & LOG_DISASM) {
-          set_log_parameters(log_parameters_ & ~LOG_DISASM);
-          cleared_log_disasm_bit = true;
-        }
-        if (number_of_instructions_to_execute > 1) {
-          // Execute one instruction and restore LOG_DISASM if necessary.
-          ExecuteInstruction();
-          --number_of_instructions_to_execute;
-          if (cleared_log_disasm_bit == true) {
-            set_log_parameters(log_parameters_ | LOG_DISASM);
-            cleared_log_disasm_bit = false;
-          }
-        }
-        // Execute the instructions.
-        while (number_of_instructions_to_execute-- > 0) {
-          ExecuteInstruction();
-        }
+
+        // If it was necessary, the pc has already been updated or incremented
+        // when executing the instruction. So we do not want it to be updated
+        // again. It will be cleared when exiting.
+        pc_modified_ = true;
 
       // next / n --------------------------------------------------------------
       } else if ((strcmp(cmd, "next") == 0) || (strcmp(cmd, "n") == 0)) {
         // Tell the simulator to break after the next executed BL.
         break_on_next_ = true;
         // Continue.
         done = true;
 
       // continue / cont / c ---------------------------------------------------
       } else if ((strcmp(cmd, "continue") == 0) ||
@@ skipping 11 matching lines @@
         if (argc >= 2) {  // disasm <n of instrs>
           GetValue(arg1, &n_of_instrs_to_disasm);
         }
         if (argc >= 3) {  // disasm <n of instrs> <address>
           GetValue(arg2, &address);
         }
 
         // Disassemble.
         PrintInstructionsAt(reinterpret_cast<Instruction*>(address),
                             n_of_instrs_to_disasm);
+        PrintF("\n");
 
       // print / p -------------------------------------------------------------
       } else if ((strcmp(cmd, "print") == 0) || (strcmp(cmd, "p") == 0)) {
         if (argc == 2) {
           if (strcmp(arg1, "all") == 0) {
             // TODO(all): better support for printing in the debugger.
             PrintRegisters(true);
             PrintFPRegisters(true);
           } else {
             if (!PrintValue(arg1)) {
@@ skipping 598 matching lines @@
     default:
       UNIMPLEMENTED();
   }
 }
 
 #endif  // USE_SIMULATOR
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_A64