Use shouldNotReachHere for compiler bugs

Previously, we followed CPython and used SystemError where
a compiler bug caused an exception to not be on the stack
when it should. For graalpy, shouldNotReachHere makes more sense.

Author: Adam Hrbac

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/ErrorMessages.java

@@ -296,7 +296,6 @@ public abstract class ErrorMessages {
     public static final TruffleString EXPECTED_BYTES_P_FOUND = tsLiteral("expected bytes, %p found");
     public static final TruffleString EXPECTED_CHARACTER_BUT_STRING_FOUND = tsLiteral("%s expected a character, but string of length %d found");
     public static final TruffleString EXPECTED_CONVERSION = tsLiteral("expected conversion");
-    public static final TruffleString EXPECTED_EXCEPTION_ON_THE_STACK = tsLiteral("expected exception on the stack");
     public static final TruffleString EXPECTED_FSPATH_TO_RETURN_STR_OR_BYTES = tsLiteral("expected %p.__fspath__() to return str or bytes, not %p");
     public static final TruffleString EXPECTED_OBJ_TYPE_S_GOT_P = tsLiteral("expected object of type %s, got %p");
     public static final TruffleString EXPECTED_OBJ_TYPE_P_GOT_P = tsLiteral("expected object of type %p, got %p");

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/bytecode/EndAsyncForNode.java

@@ -40,11 +40,8 @@
  */
 package com.oracle.graal.python.nodes.bytecode;
 
-import static com.oracle.graal.python.builtins.PythonBuiltinClassType.SystemError;
-
 import com.oracle.graal.python.builtins.PythonBuiltinClassType;
 import com.oracle.graal.python.builtins.objects.PNone;
-import com.oracle.graal.python.nodes.ErrorMessages;
 import com.oracle.graal.python.nodes.PNodeWithContext;
 import com.oracle.graal.python.nodes.PRaiseNode;
 import com.oracle.graal.python.nodes.object.IsBuiltinClassProfile;
@@ -90,8 +87,7 @@ public void doGeneric(Object exception, boolean rootNodeVisible,
             } else if (exception instanceof AbstractTruffleException) {
                 throw (AbstractTruffleException) exception;
             } else {
-                CompilerDirectives.transferToInterpreterAndInvalidate();
-                throw raiseNode.raise(SystemError, ErrorMessages.EXPECTED_EXCEPTION_ON_THE_STACK);
+                throw CompilerDirectives.shouldNotReachHere("Exception not on stack");
             }
 
         }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/bytecode/ExitAWithNode.java

@@ -40,12 +40,9 @@
  */
 package com.oracle.graal.python.nodes.bytecode;
 
-import static com.oracle.graal.python.builtins.PythonBuiltinClassType.SystemError;
-
 import com.oracle.graal.python.builtins.objects.PNone;
 import com.oracle.graal.python.builtins.objects.function.PArguments;
 import com.oracle.graal.python.lib.PyObjectIsTrueNode;
-import com.oracle.graal.python.nodes.ErrorMessages;
 import com.oracle.graal.python.nodes.PNodeWithContext;
 import com.oracle.graal.python.nodes.PRaiseNode;
 import com.oracle.graal.python.runtime.exception.PException;
@@ -78,8 +75,7 @@ int exit(VirtualFrame virtualFrame, int stackTopIn, boolean rootNodeVisible,
                 } else if (exception instanceof AbstractTruffleException) {
                     throw (AbstractTruffleException) exception;
                 } else {
-                    CompilerDirectives.transferToInterpreterAndInvalidate();
-                    throw raiseNode.raise(SystemError, ErrorMessages.EXPECTED_EXCEPTION_ON_THE_STACK);
+                    throw CompilerDirectives.shouldNotReachHere("Exception not on stack");
                 }
             }
         } finally {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/bytecode/ExitWithNode.java

@@ -40,14 +40,11 @@
  */
 package com.oracle.graal.python.nodes.bytecode;
 
-import static com.oracle.graal.python.builtins.PythonBuiltinClassType.SystemError;
-
 import com.oracle.graal.python.builtins.objects.PNone;
 import com.oracle.graal.python.builtins.objects.exception.GetExceptionTracebackNode;
 import com.oracle.graal.python.builtins.objects.function.PArguments;
 import com.oracle.graal.python.builtins.objects.type.SpecialMethodSlot;
 import com.oracle.graal.python.lib.PyObjectIsTrueNode;
-import com.oracle.graal.python.nodes.ErrorMessages;
 import com.oracle.graal.python.nodes.PNodeWithContext;
 import com.oracle.graal.python.nodes.PRaiseNode;
 import com.oracle.graal.python.nodes.call.special.CallQuaternaryMethodNode;
@@ -101,8 +98,7 @@ int exit(VirtualFrame virtualFrame, int stackTopIn, boolean rootNodeVisible,
                     } else if (exception instanceof AbstractTruffleException) {
                         throw (AbstractTruffleException) exception;
                     } else {
-                        CompilerDirectives.transferToInterpreterAndInvalidate();
-                        throw raiseNode.raise(SystemError, ErrorMessages.EXPECTED_EXCEPTION_ON_THE_STACK);
+                        throw CompilerDirectives.shouldNotReachHere("Exception not on stack");
                     }
                 }
             } finally {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/bytecode/PBytecodeRootNode.java

@@ -4653,8 +4653,7 @@ private PException bytecodeEndExcHandler(VirtualFrame virtualFrame, int stackTop
         } else if (exception instanceof AbstractTruffleException) {
             throw (AbstractTruffleException) exception;
         } else {
-            CompilerDirectives.transferToInterpreterAndInvalidate();
-            throw PRaiseNode.raiseUncached(this, SystemError, ErrorMessages.EXPECTED_EXCEPTION_ON_THE_STACK);
+            throw CompilerDirectives.shouldNotReachHere("Exception not on stack");
         }
     }