Fix lazy deoptimization from deferred code.

runtime/vm/flow_graph_compiler_arm64.cc

 // Copyright (c) 2014, 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_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/compiler.h"
 #include "vm/cpu.h"
 #include "vm/dart_entry.h"
 #include "vm/deopt_instructions.h"
 #include "vm/il_printer.h"
+#include "vm/instructions.h"
 #include "vm/locations.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, trap_on_deoptimization, false, "Trap on deoptimization.");
@@ skipping 1077 matching lines @@
     }
   }
 
   VisitBlocks();
 
   __ brk(0);
   ASSERT(assembler()->constant_pool_allowed());
   GenerateDeferredCode();
 
   if (is_optimizing()) {
+    // Leave enough space for patching in case of lazy deoptimization from
+    // deferred code.
+    for (intptr_t i = 0;
+      i < CallPattern::kDeoptCallLengthInInstructions;
+      ++i) {
+      __ orr(R0, ZR, Operand(R0));  // nop
+    }
     lazy_deopt_pc_offset_ = assembler()->CodeSize();
   __ BranchPatchable(*StubCode::DeoptimizeLazy_entry());
   }
 }
 
 
 void FlowGraphCompiler::GenerateCall(intptr_t token_pos,
                                      const StubEntry& stub_entry,
                                      RawPcDescriptors::Kind kind,
                                      LocationSummary* locs) {
@@ skipping 688 matching lines @@
 void ParallelMoveResolver::RestoreFpuScratch(FpuRegister reg) {
   __ PopDouble(reg);
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64