A64: Temporary fix for predictable code size in LCodeGen::DoStackCheck.

src/a64/lithium-codegen-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
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@@ skipping 4557 matching lines @@
   ASSERT(instr->HasEnvironment());
   LEnvironment* env = instr->environment();
   // There is no LLazyBailout instruction for stack-checks. We have to
   // prepare for lazy deoptimization explicitly here.
   if (instr->hydrogen()->is_function_entry()) {
     // Perform stack overflow check.
     Label done;
     __ CompareRoot(masm()->StackPointer(), Heap::kStackLimitRootIndex);
     __ B(hs, &done);
 
-    // TODO(jbramley): This PredictableCodeSizeScope fails sometimes. Sometimes
-    // the code tries to generate 3 instructions, and sometimes it tries to
-    // generate 2. Work out why, and fix it.
+    // TODO(bafsa): Make sure that the EnsureSpaceForLazyDeopt inside
+    // CallCodeGeneric will not insert any nop while calling the stub by
+    // inserting them now. The EnsureSpaceForLazyDeopt in CallCodeGeneric
+    // will go away at some point during the rebase (r18642) so this will become
+    // unecessary and should be removed at this point.
+    EnsureSpaceForLazyDeopt();
+
     PredictableCodeSizeScope predictable(masm_,
                                          Assembler::kCallSizeWithRelocation);
     StackCheckStub stub;
     CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
     EnsureSpaceForLazyDeopt();
     last_lazy_deopt_pc_ = masm()->pc_offset();
 
     __ Bind(&done);
     RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
     safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
@@ skipping 902 matching lines @@
   __ Bind(&out_of_object);
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal