Improve and simplify removal of unreachable code

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 80 matching lines @@
   info()->CommitDependencies(code);
 }
 
 
 void LCodeGen::Abort(BailoutReason reason) {
   info()->set_bailout_reason(reason);
   status_ = ABORTED;
 }
 
 
-void LCodeGen::Comment(const char* format, ...) {
-  if (!FLAG_code_comments) return;
-  char buffer[4 * KB];
-  StringBuilder builder(buffer, ARRAY_SIZE(buffer));
-  va_list arguments;
-  va_start(arguments, format);
-  builder.AddFormattedList(format, arguments);
-  va_end(arguments);
-
-  // Copy the string before recording it in the assembler to avoid
-  // issues when the stack allocated buffer goes out of scope.
-  size_t length = builder.position();
-  Vector<char> copy = Vector<char>::New(length + 1);
-  OS::MemCopy(copy.start(), builder.Finalize(), copy.length());
-  masm()->RecordComment(copy.start());
-}
-
-
 bool LCodeGen::GeneratePrologue() {
   ASSERT(is_generating());
 
   if (info()->IsOptimizing()) {
     ProfileEntryHookStub::MaybeCallEntryHook(masm_);
 
 #ifdef DEBUG
     if (strlen(FLAG_stop_at) > 0 &&
         info_->function()->name()->IsUtf8EqualTo(CStrVector(FLAG_stop_at))) {
       __ stop("stop_at");
@@ skipping 135 matching lines @@
   osr_pc_offset_ = masm()->pc_offset();
 
   // Adjust the frame size, subsuming the unoptimized frame into the
   // optimized frame.
   int slots = GetStackSlotCount() - graph()->osr()->UnoptimizedFrameSlots();
   ASSERT(slots >= 0);
   __ sub(sp, sp, Operand(slots * kPointerSize));
 }
 
 
-bool LCodeGen::GenerateBody() {
-  ASSERT(is_generating());
-  bool emit_instructions = true;
-  for (current_instruction_ = 0;
-       !is_aborted() && current_instruction_ < instructions_->length();
-       current_instruction_++) {
-    LInstruction* instr = instructions_->at(current_instruction_);
-
-    // Don't emit code for basic blocks with a replacement.
-    if (instr->IsLabel()) {
-      emit_instructions = !LLabel::cast(instr)->HasReplacement();
-    }
-    if (!emit_instructions) continue;
-
-    if (FLAG_code_comments && instr->HasInterestingComment(this)) {
-      Comment(";;; <@%d,#%d> %s",
-              current_instruction_,
-              instr->hydrogen_value()->id(),
-              instr->Mnemonic());
-    }
-
-    RecordAndUpdatePosition(instr->position());
-
-    instr->CompileToNative(this);
-  }
-  EnsureSpaceForLazyDeopt();
-  last_lazy_deopt_pc_ = masm()->pc_offset();
-  return !is_aborted();
-}
-
-
 bool LCodeGen::GenerateDeferredCode() {
   ASSERT(is_generating());
   if (deferred_.length() > 0) {
     for (int i = 0; !is_aborted() && i < deferred_.length(); i++) {
       LDeferredCode* code = deferred_[i];
 
       int pos = instructions_->at(code->instruction_index())->position();
       RecordAndUpdatePosition(pos);
 
       Comment(";;; <@%d,#%d> "
@@ skipping 407 matching lines @@
                         TargetAddressStorageMode storage_mode) {
   CallCodeGeneric(code, mode, instr, RECORD_SIMPLE_SAFEPOINT, storage_mode);
 }
 
 
 void LCodeGen::CallCodeGeneric(Handle<Code> code,
                                RelocInfo::Mode mode,
                                LInstruction* instr,
                                SafepointMode safepoint_mode,
                                TargetAddressStorageMode storage_mode) {
-  EnsureSpaceForLazyDeopt();
+  EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
   ASSERT(instr != NULL);
   // Block literal pool emission to ensure nop indicating no inlined smi code
   // is in the correct position.
   Assembler::BlockConstPoolScope block_const_pool(masm());
   LPointerMap* pointers = instr->pointer_map();
   RecordPosition(pointers->position());
   __ Call(code, mode, TypeFeedbackId::None(), al, storage_mode);
   RecordSafepointWithLazyDeopt(instr, safepoint_mode);
 
   // Signal that we don't inline smi code before these stubs in the
@@ skipping 1437 matching lines @@
 
   BinaryOpStub stub(instr->op(), NO_OVERWRITE);
   // Block literal pool emission to ensure nop indicating no inlined smi code
   // is in the correct position.
   Assembler::BlockConstPoolScope block_const_pool(masm());
   CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
   __ nop();  // Signals no inlined code.
 }
 
 
-int LCodeGen::GetNextEmittedBlock() const {
-  for (int i = current_block_ + 1; i < graph()->blocks()->length(); ++i) {
-    if (!chunk_->GetLabel(i)->HasReplacement()) return i;
-  }
-  return -1;
-}
-
 template<class InstrType>
 void LCodeGen::EmitBranch(InstrType instr, Condition condition) {
   int left_block = instr->TrueDestination(chunk_);
   int right_block = instr->FalseDestination(chunk_);
 
   int next_block = GetNextEmittedBlock();
 
   if (right_block == left_block || condition == al) {
     EmitGoto(left_block);
   } else if (left_block == next_block) {
@@ skipping 3419 matching lines @@
   __ b(ne, &check_frame_marker);
   __ ldr(temp1, MemOperand(temp1, StandardFrameConstants::kCallerFPOffset));
 
   // Check the marker in the calling frame.
   __ bind(&check_frame_marker);
   __ ldr(temp1, MemOperand(temp1, StandardFrameConstants::kMarkerOffset));
   __ cmp(temp1, Operand(Smi::FromInt(StackFrame::CONSTRUCT)));
 }
 
 
-void LCodeGen::EnsureSpaceForLazyDeopt() {
+void LCodeGen::EnsureSpaceForLazyDeopt(int space_needed) {
   if (info()->IsStub()) return;
   // Ensure that we have enough space after the previous lazy-bailout
   // instruction for patching the code here.
   int current_pc = masm()->pc_offset();
-  int patch_size = Deoptimizer::patch_size();
-  if (current_pc < last_lazy_deopt_pc_ + patch_size) {
+  if (current_pc < last_lazy_deopt_pc_ + space_needed) {
     // Block literal pool emission for duration of padding.
     Assembler::BlockConstPoolScope block_const_pool(masm());
-    int padding_size = last_lazy_deopt_pc_ + patch_size - current_pc;
+    int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     ASSERT_EQ(0, padding_size % Assembler::kInstrSize);
     while (padding_size > 0) {
       __ nop();
       padding_size -= Assembler::kInstrSize;
     }
   }
 }
 
 
 void LCodeGen::DoLazyBailout(LLazyBailout* instr) {
-  EnsureSpaceForLazyDeopt();
+  EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
   last_lazy_deopt_pc_ = masm()->pc_offset();
   ASSERT(instr->HasEnvironment());
   LEnvironment* env = instr->environment();
   RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
   safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
 }
 
 
 void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
   Deoptimizer::BailoutType type = instr->hydrogen()->type();
@@ skipping 49 matching lines @@
     Label done;
     __ LoadRoot(ip, Heap::kStackLimitRootIndex);
     __ cmp(sp, Operand(ip));
     __ b(hs, &done);
     PredictableCodeSizeScope predictable(masm_, 2 * Assembler::kInstrSize);
     ASSERT(instr->context()->IsRegister());
     ASSERT(ToRegister(instr->context()).is(cp));
     CallCode(isolate()->builtins()->StackCheck(),
               RelocInfo::CODE_TARGET,
               instr);
-    EnsureSpaceForLazyDeopt();
+    EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
     last_lazy_deopt_pc_ = masm()->pc_offset();
     __ bind(&done);
     RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
     safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
   } else {
     ASSERT(instr->hydrogen()->is_backwards_branch());
     // Perform stack overflow check if this goto needs it before jumping.
     DeferredStackCheck* deferred_stack_check =
         new(zone()) DeferredStackCheck(this, instr);
     __ LoadRoot(ip, Heap::kStackLimitRootIndex);
     __ cmp(sp, Operand(ip));
     __ b(lo, deferred_stack_check->entry());
-    EnsureSpaceForLazyDeopt();
+    EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
     last_lazy_deopt_pc_ = masm()->pc_offset();
     __ bind(instr->done_label());
     deferred_stack_check->SetExit(instr->done_label());
     RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
     // Don't record a deoptimization index for the safepoint here.
     // This will be done explicitly when emitting call and the safepoint in
     // the deferred code.
   }
 }
 
@@ skipping 103 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal