Remove a brittle assertion from Turbofan lazy deoptimization handling.

As discussed in person with Benedikt, it is better to remove the assertion because it is too brittle. The assertion says that the continuation block should immediately follow the call. However, there are exceptions - such as nop or constant pool in-between being fine - that make the assertion brittle.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/471523002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23102 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/arm/code-generator-arm.cc

@@ -832,16 +832,6 @@ void CodeGenerator::AddNopForSmiCodeInlining() {
   UNREACHABLE();
 }
 
-#ifdef DEBUG
-
-// Checks whether the code between start_pc and end_pc is a no-op.
-bool CodeGenerator::IsNopForSmiCodeInlining(Handle<Code> code, int start_pc,
-                                            int end_pc) {
-  return false;
-}
-
-#endif  // DEBUG
-
 #undef __
 }
 }

src/compiler/arm64/code-generator-arm64.cc

@@ -832,23 +832,6 @@ void CodeGenerator::AddNopForSmiCodeInlining() { __ movz(xzr, 0); }
 
 #undef __
 
-#if DEBUG
-
-// Checks whether the code between start_pc and end_pc is a no-op.
-bool CodeGenerator::IsNopForSmiCodeInlining(Handle<Code> code, int start_pc,
-                                            int end_pc) {
-  if (start_pc + 4 != end_pc) {
-    return false;
-  }
-  Address instr_address = code->instruction_start() + start_pc;
-
-  v8::internal::Instruction* instr =
-      reinterpret_cast<v8::internal::Instruction*>(instr_address);
-  return instr->IsMovz() && instr->Rd() == xzr.code() && instr->SixtyFourBits();
-}
-
-#endif  // DEBUG
-
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8

src/compiler/code-generator.cc

@@ -225,9 +225,6 @@ void CodeGenerator::PopulateDeoptimizationData(Handle<Code> code_object) {
   // Populate the return address patcher entries.
   for (int i = 0; i < patch_count; ++i) {
     LazyDeoptimizationEntry entry = lazy_deoptimization_entries_[i];
-    DCHECK(entry.position_after_call() == entry.continuation()->pos() ||
-           IsNopForSmiCodeInlining(code_object, entry.position_after_call(),
-                                   entry.continuation()->pos()));
     data->SetReturnAddressPc(i, Smi::FromInt(entry.position_after_call()));
     data->SetPatchedAddressPc(i, Smi::FromInt(entry.deoptimization()->pos()));
   }
@@ -365,15 +362,6 @@ void CodeGenerator::AssembleSwap(InstructionOperand* source,
 
 void CodeGenerator::AddNopForSmiCodeInlining() { UNIMPLEMENTED(); }
 
-
-#ifdef DEBUG
-bool CodeGenerator::IsNopForSmiCodeInlining(Handle<Code> code, int start_pc,
-                                            int end_pc) {
-  UNIMPLEMENTED();
-  return false;
-}
-#endif
-
 #endif  // !V8_TURBOFAN_BACKEND
 
 }  // namespace compiler

src/compiler/code-generator.h

@@ -88,10 +88,6 @@ class CodeGenerator V8_FINAL : public GapResolver::Assembler {
   void AddTranslationForOperand(Translation* translation, Instruction* instr,
                                 InstructionOperand* op);
   void AddNopForSmiCodeInlining();
-#if DEBUG
-  static bool IsNopForSmiCodeInlining(Handle<Code> code, int start_pc,
-                                      int end_pc);
-#endif  // DEBUG
   // ===========================================================================
 
   class LazyDeoptimizationEntry V8_FINAL {

src/compiler/ia32/code-generator-ia32.cc

@@ -938,19 +938,6 @@ void CodeGenerator::AddNopForSmiCodeInlining() { __ nop(); }
 
 #undef __
 
-#ifdef DEBUG
-
-// Checks whether the code between start_pc and end_pc is a no-op.
-bool CodeGenerator::IsNopForSmiCodeInlining(Handle<Code> code, int start_pc,
-                                            int end_pc) {
-  if (start_pc + 1 != end_pc) {
-    return false;
-  }
-  return *(code->instruction_start() + start_pc) ==
-         v8::internal::Assembler::kNopByte;
-}
-
-#endif  // DEBUG
 }
 }
 }  // namespace v8::internal::compiler

src/compiler/x64/code-generator-x64.cc

@@ -982,20 +982,6 @@ void CodeGenerator::AddNopForSmiCodeInlining() { __ nop(); }
 
 #undef __
 
-#ifdef DEBUG
-
-// Checks whether the code between start_pc and end_pc is a no-op.
-bool CodeGenerator::IsNopForSmiCodeInlining(Handle<Code> code, int start_pc,
-                                            int end_pc) {
-  if (start_pc + 1 != end_pc) {
-    return false;
-  }
-  return *(code->instruction_start() + start_pc) ==
-         v8::internal::Assembler::kNopByte;
-}
-
-#endif
-
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8

test/cctest/cctest.status

@@ -179,11 +179,6 @@
 
   'test-api/Bug618': [PASS],
 
-  # TODO(turbofan): Deoptimization support buggy with snapshot=off.
-  'test-run-deopt/*': [PASS, ['no_snap == True', NO_VARIANTS]],
-  'test-deoptimization/*': [PASS, ['no_snap == True', NO_VARIANTS]],
-  'test-scheduler/BuildScheduleTrivialLazyDeoptCall': [PASS, ['no_snap == True', NO_VARIANTS]],
-
   # BUG(v8:3385).
   'test-serialize/DeserializeFromSecondSerialization': [PASS, FAIL],
   'test-serialize/DeserializeFromSecondSerializationAndRunScript2': [PASS, FAIL],