Fix stack pointer reset bug in entry to catch blocks.

vm/code_generator_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/code_generator.h"
 
 #include "lib/error.h"
@@ skipping 2564 matching lines @@
 
 void CodeGenerator::VisitCatchClauseNode(CatchClauseNode* node) {
   // NOTE: The implicit variables ':saved_context', ':exception_var'
   // and ':stacktrace_var' can never be captured variables.
   // Restore CTX from local variable ':saved_context'.
   GenerateLoadVariable(CTX, node->context_var());
 
   // Restore RSP from RBP as we are coming from a throw and the code for
   // popping arguments has not been run.
   ASSERT(locals_space_size() >= 0);
-  __ movq(RSP, RBP);
-  __ subq(RSP, Immediate(locals_space_size()));
+  if (locals_space_size() == 0) {
+    __ movq(RSP, RBP);
+  } else {
+    __ leaq(RSP, Address(RBP, -locals_space_size()));
+  }
 
   // The JumpToExceptionHandler trampoline code sets up
   // - the exception object in RAX (kExceptionObjectReg)
   // - the stacktrace object in register RDX (kStackTraceObjectReg)
   // We now setup the exception object and the trace object
   // so that the handler code has access to these objects.
   GenerateStoreVariable(node->exception_var(),
                         kExceptionObjectReg,
                         kNoRegister);
   GenerateStoreVariable(node->stacktrace_var(),
@@ skipping 131 matching lines @@
   const Error& error = Error::Handle(
       Parser::FormatError(script, token_index, "Error", format, args));
   va_end(args);
   Isolate::Current()->long_jump_base()->Jump(1, error);
   UNREACHABLE();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64