* interp.c (sim_engine_run): Reset the ZERO register to zero

regardless of FEATURE_WARN_ZERO.

sim/mips/ChangeLog

@@ -1,5 +1,7 @@
 Wed Jul  2 11:54:10 1997  Jeffrey A Law  (law@cygnus.com)
 
+	* interp.c (sim_engine_run): Reset the ZERO register to zero
+	regardless of FEATURE_WARN_ZERO.
 	* gencode.c (FEATURE_WARNINGS): Remove FEATURE_WARN_ZERO.
 
 Wed Jun  4 10:43:14 1997  Andrew Cagney  <cagney@b1.cygnus.com>

sim/mips/interp.c

@@ -2795,21 +2795,13 @@ SignalException (int exception,...)
        sim_warning("ReservedInstruction 0x%08X at IPC = 0x%s",instruction,pr_addr(IPC));
      }
 
-    default:
+    case BreakPoint:
 #ifdef DEBUG
-     if (exception != BreakPoint)
 	callback->printf_filtered(callback,"DBG: SignalException(%d) IPC = 0x%s\n",exception,pr_addr(IPC));
 #endif /* DEBUG */
-     /* Store exception code into current exception id variable (used
-        by exit code): */
-
-     /* TODO: If not simulating exceptions then stop the simulator
-        execution. At the moment we always stop the simulation. */
-     /* state |= (simSTOP | simEXCEPTION); */
-
       /* Keep a copy of the current A0 in-case this is the program exit
 	 breakpoint:  */
-     if (exception == BreakPoint) {
+      {
 	va_list ap;
 	unsigned int instruction;
 	va_start(ap,exception);
@@ -2821,6 +2813,19 @@ SignalException (int exception,...)
 			   sim_exited, (unsigned int)(A0 & 0xFFFFFFFF));
 	}
       }
+      if (state & simDELAYSLOT)
+	PC = IPC - 4; /* reference the branch instruction */
+      else
+	PC = IPC;
+      sim_engine_halt (sd, STATE_CPU (sd, 0), NULL, NULL_CIA,
+		       sim_stopped, SIGTRAP);
+
+    default:
+     /* Store exception code into current exception id variable (used
+        by exit code): */
+
+     /* TODO: If not simulating exceptions then stop the simulator
+        execution. At the moment we always stop the simulation. */
 
      /* See figure 5-17 for an outline of the code below */
      if (! (SR & status_EXL))
@@ -2839,7 +2844,7 @@ SignalException (int exception,...)
        }
      else
        {
-	 CAUSE = 0;
+	 CAUSE = (exception << 2);
 	 vector = 0x180;
        }
      SR |= status_EXL;
@@ -2884,11 +2889,15 @@ SignalException (int exception,...)
        case Trap:
        case Watch:
        case SystemCall:
-       case BreakPoint:
 	 PC = EPC;
 	 sim_engine_halt (sd, STATE_CPU (sd, 0), NULL, NULL_CIA,
 			  sim_stopped, SIGTRAP);
 
+       case BreakPoint:
+	 PC = EPC;
+	 sim_engine_abort (sd, STATE_CPU (sd, 0), NULL_CIA,
+			   "FATAL: Should not encounter a breakpoint\n");
+
        default : /* Unknown internal exception */
 	 PC = EPC;
 	 sim_engine_halt (sd, STATE_CPU (sd, 0), NULL, NULL_CIA,
@@ -4111,6 +4120,12 @@ decode_coproc(instruction)
 		  SR = GPR[rt];
 		break;
 		/* 13 = Cause              R4000   VR4100  VR4300 */
+	      case 13:
+		if (code == 0x00)
+		  GPR[rt] = CAUSE;
+		else
+		  CAUSE = GPR[rt];
+		break;
 		/* 14 = EPC                R4000   VR4100  VR4300 */
 		/* 15 = PRId               R4000   VR4100  VR4300 */
 		/* 16 = Config             R4000   VR4100  VR4300 */
@@ -4362,16 +4377,16 @@ sim_engine_run (sd, next_cpu_nr, siggnal)
        LO1ACCESS--;
 #endif /* WARN_LOHI */
 
-#if defined(WARN_ZERO)
       /* For certain MIPS architectures, GPR[0] is hardwired to zero. We
          should check for it being changed. It is better doing it here,
          than within the simulator, since it will help keep the simulator
          small. */
       if (ZERO != 0) {
+#if defined(WARN_ZERO)
         sim_warning("The ZERO register has been updated with 0x%s (PC = 0x%s) (reset back to zero)",pr_addr(ZERO),pr_addr(IPC));
+#endif /* WARN_ZERO */
         ZERO = 0; /* reset back to zero before next instruction */
       }
-#endif /* WARN_ZERO */
     } else /* simSKIPNEXT check */
      state &= ~simSKIPNEXT;