Ensure that BoxInt32 input is correctly preserved on the slow-path.

runtime/vm/flow_graph_compiler_arm.cc

 // Copyright (c) 2013, 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_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 1381 matching lines @@
     __ Pop(left);
   } else {
     __ cmp(left, Operand(right));
   }
 }
 
 
 // This function must be in sync with FlowGraphCompiler::RecordSafepoint and
 // FlowGraphCompiler::SlowPathEnvironmentFor.
 void FlowGraphCompiler::SaveLiveRegisters(LocationSummary* locs) {
+#if defined(DEBUG)
+  locs->CheckWritableInputs();
+#endif
+
   // TODO(vegorov): consider saving only caller save (volatile) registers.
   const intptr_t fpu_regs_count = locs->live_registers()->FpuRegisterCount();
   if (fpu_regs_count > 0) {
     __ AddImmediate(SP, -(fpu_regs_count * kFpuRegisterSize));
     // Store fpu registers with the lowest register number at the lowest
     // address.
     intptr_t offset = 0;
     for (intptr_t reg_idx = 0; reg_idx < kNumberOfFpuRegisters; ++reg_idx) {
       QRegister fpu_reg = static_cast<QRegister>(reg_idx);
       if (locs->live_registers()->ContainsFpuRegister(fpu_reg)) {
@@ skipping 368 matching lines @@
   DRegister dreg = EvenDRegisterOf(reg);
   __ vldrd(dreg, Address(SP, kDoubleSize, Address::PostIndex));
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM