Remove BailoutState and pad accumulator for arm64.

Bug: v8:6644
Change-Id: I5cd713465563f2dc803b175684bf04a05559e653
Reviewed-on: https://chromium-review.googlesource.com/693239
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48285}

src/arm/deoptimizer-arm.cc

@@ -210,9 +210,7 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ vldr(reg, r1, src_offset);
   }
 
-  // Push state, pc, and continuation from the last output frame.
-  __ ldr(r6, MemOperand(r2, FrameDescription::state_offset()));
-  __ push(r6);
+  // Push pc and continuation from the last output frame.
   __ ldr(r6, MemOperand(r2, FrameDescription::pc_offset()));
   __ push(r6);
   __ ldr(r6, MemOperand(r2, FrameDescription::continuation_offset()));
@@ -295,6 +293,7 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   __ push(scratch);
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return false; }
 
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);

src/arm64/deoptimizer-arm64.cc

@@ -202,10 +202,6 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ Ldr(reg, MemOperand(x1, src_offset));
   }
 
-  // Push state from the last output frame.
-  __ Ldr(x6, MemOperand(current_frame, FrameDescription::state_offset()));
-  __ Push(x6);
-
   // TODO(all): ARM copies a lot (if not all) of the last output frame onto the
   // stack, then pops it all into registers. Here, we try to load it directly
   // into the relevant registers. Is this correct? If so, we should improve the
@@ -276,6 +272,7 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   __ Push(entry_id);
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return true; }
 
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);

src/builtins/arm/builtins-arm.cc

@@ -1513,7 +1513,6 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     __ pop(r0);
   }
 
-  __ add(sp, sp, Operand(kPointerSize));  // Ignore state
   __ mov(pc, lr);                         // Jump to ContinueToBuiltin stub
 }
 
@@ -1575,28 +1574,9 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     __ CallRuntime(Runtime::kNotifyDeoptimized);
   }
 
-  // Get the full codegen state from the stack and untag it -> r6.
-  __ ldr(r6, MemOperand(sp, 0 * kPointerSize));
-  __ SmiUntag(r6);
-  // Switch on the state.
-  Label with_tos_register, unknown_state;
-  __ cmp(r6,
-         Operand(static_cast<int>(Deoptimizer::BailoutState::NO_REGISTERS)));
-  __ b(ne, &with_tos_register);
-  __ add(sp, sp, Operand(1 * kPointerSize));  // Remove state.
-  __ Ret();
-
-  __ bind(&with_tos_register);
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), r0.code());
-  __ ldr(r0, MemOperand(sp, 1 * kPointerSize));
-  __ cmp(r6,
-         Operand(static_cast<int>(Deoptimizer::BailoutState::TOS_REGISTER)));
-  __ b(ne, &unknown_state);
-  __ add(sp, sp, Operand(2 * kPointerSize));  // Remove state.
+  __ pop(r0);
   __ Ret();
-
-  __ bind(&unknown_state);
-  __ stop("no cases left");
 }
 
 static void Generate_OnStackReplacementHelper(MacroAssembler* masm,

src/builtins/arm64/builtins-arm64.cc

@@ -1547,9 +1547,6 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     __ Pop(x0);
   }
 
-  // Ignore state (pushed by Deoptimizer::EntryGenerator::Generate).
-  __ Drop(1);
-
   // Jump to the ContinueToBuiltin stub. Deoptimizer::EntryGenerator::Generate
   // loads this into lr before it jumps here.
   __ Br(lr);
@@ -1612,31 +1609,10 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     __ CallRuntime(Runtime::kNotifyDeoptimized);
   }
 
-  // Get the full codegen state from the stack and untag it.
-  Register state = x6;
-  __ Peek(state, 0);
-  __ SmiUntag(state);
-
-  // Switch on the state.
-  Label with_tos_register, unknown_state;
-  __ CompareAndBranch(state,
-                      static_cast<int>(Deoptimizer::BailoutState::NO_REGISTERS),
-                      ne, &with_tos_register);
-  __ Drop(1);  // Remove state.
-  __ Ret();
-
-  __ Bind(&with_tos_register);
-  // Reload TOS register.
+  // Pop TOS register and padding.
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), x0.code());
-  __ Peek(x0, kPointerSize);
-  __ CompareAndBranch(state,
-                      static_cast<int>(Deoptimizer::BailoutState::TOS_REGISTER),
-                      ne, &unknown_state);
-  __ Drop(2);  // Remove state and TOS.
+  __ Pop(x0, padreg);
   __ Ret();
-
-  __ Bind(&unknown_state);
-  __ Abort(kInvalidFullCodegenState);
 }
 
 static void Generate_OnStackReplacementHelper(MacroAssembler* masm,

src/builtins/ia32/builtins-ia32.cc

@@ -1562,8 +1562,7 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     // Tear down internal frame.
   }
 
-  __ pop(MemOperand(esp, 0));  // Ignore state offset
-  __ ret(0);  // Return to ContinueToBuiltin stub still on stack.
+  __ Ret();  // Return to ContinueToBuiltin stub still on stack.
 }
 
 namespace {
@@ -1624,25 +1623,9 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     // Tear down internal frame.
   }
 
-  // Get the full codegen state from the stack and untag it.
-  __ mov(ecx, Operand(esp, 1 * kPointerSize));
-  __ SmiUntag(ecx);
-
-  // Switch on the state.
-  Label not_no_registers, not_tos_eax;
-  __ cmp(ecx, static_cast<int>(Deoptimizer::BailoutState::NO_REGISTERS));
-  __ j(not_equal, &not_no_registers, Label::kNear);
-  __ ret(1 * kPointerSize);  // Remove state.
-
-  __ bind(&not_no_registers);
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), eax.code());
-  __ mov(eax, Operand(esp, 2 * kPointerSize));
-  __ cmp(ecx, static_cast<int>(Deoptimizer::BailoutState::TOS_REGISTER));
-  __ j(not_equal, &not_tos_eax, Label::kNear);
-  __ ret(2 * kPointerSize);  // Remove state, eax.
-
-  __ bind(&not_tos_eax);
-  __ Abort(kNoCasesLeft);
+  __ mov(eax, Operand(esp, 1 * kPointerSize));
+  __ ret(1 * kPointerSize);  // Remove eax.
 }
 
 // static

src/builtins/mips/builtins-mips.cc

@@ -1488,7 +1488,6 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     __ Pop(v0);
   }
 
-  __ Addu(sp, sp, Operand(kPointerSize));  // Ignore state
   __ Jump(ra);                             // Jump to the ContinueToBuiltin stub
 }
 
@@ -1548,29 +1547,11 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     __ CallRuntime(Runtime::kNotifyDeoptimized);
   }
 
-  // Get the full codegen state from the stack and untag it -> t2.
-  __ lw(t2, MemOperand(sp, 0 * kPointerSize));
-  __ SmiUntag(t2);
-  // Switch on the state.
-  Label with_tos_register, unknown_state;
-  __ Branch(&with_tos_register, ne, t2,
-            Operand(static_cast<int>(Deoptimizer::BailoutState::NO_REGISTERS)));
-  __ Ret(USE_DELAY_SLOT);
-  // Safe to fill delay slot Addu will emit one instruction.
-  __ Addu(sp, sp, Operand(1 * kPointerSize));  // Remove state.
-
-  __ bind(&with_tos_register);
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), v0.code());
-  __ lw(v0, MemOperand(sp, 1 * kPointerSize));
-  __ Branch(&unknown_state, ne, t2,
-            Operand(static_cast<int>(Deoptimizer::BailoutState::TOS_REGISTER)));
-
+  __ lw(v0, MemOperand(sp, 0 * kPointerSize));
   __ Ret(USE_DELAY_SLOT);
   // Safe to fill delay slot Addu will emit one instruction.
-  __ Addu(sp, sp, Operand(2 * kPointerSize));  // Remove state.
-
-  __ bind(&unknown_state);
-  __ stop("no cases left");
+  __ Addu(sp, sp, Operand(1 * kPointerSize));  // Remove accumulator.
 }
 
 static void Generate_OnStackReplacementHelper(MacroAssembler* masm,

src/builtins/mips64/builtins-mips64.cc

@@ -1492,7 +1492,6 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     __ pop(v0);
   }
 
-  __ Daddu(sp, sp, Operand(kPointerSize));  // Ignore state
   __ Jump(ra);  // Jump to the ContinueToBuiltin stub
 }
 
@@ -1552,30 +1551,11 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     __ CallRuntime(Runtime::kNotifyDeoptimized);
   }
 
-  // Get the full codegen state from the stack and untag it -> a6.
-  __ Lw(a6, UntagSmiMemOperand(sp, 0 * kPointerSize));
-  // Switch on the state.
-  Label with_tos_register, unknown_state;
-  __ Branch(
-      &with_tos_register, ne, a6,
-      Operand(static_cast<int64_t>(Deoptimizer::BailoutState::NO_REGISTERS)));
-  __ Ret(USE_DELAY_SLOT);
-  // Safe to fill delay slot Addu will emit one instruction.
-  __ Daddu(sp, sp, Operand(1 * kPointerSize));  // Remove state.
-
-  __ bind(&with_tos_register);
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), v0.code());
-  __ Ld(v0, MemOperand(sp, 1 * kPointerSize));
-  __ Branch(
-      &unknown_state, ne, a6,
-      Operand(static_cast<int64_t>(Deoptimizer::BailoutState::TOS_REGISTER)));
-
+  __ Ld(v0, MemOperand(sp, 0 * kPointerSize));
   __ Ret(USE_DELAY_SLOT);
   // Safe to fill delay slot Addu will emit one instruction.
-  __ Daddu(sp, sp, Operand(2 * kPointerSize));  // Remove state.
-
-  __ bind(&unknown_state);
-  __ stop("no cases left");
+  __ Daddu(sp, sp, Operand(1 * kPointerSize));  // Remove state.
 }
 
 static void Generate_OnStackReplacementHelper(MacroAssembler* masm,

src/builtins/ppc/builtins-ppc.cc

@@ -1530,7 +1530,6 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     __ pop(r3);
   }
 
-  __ addi(sp, sp, Operand(kPointerSize));  // Ignore state
   __ blr();                                // Jump to ContinueToBuiltin stub
 }
 
@@ -1592,30 +1591,10 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     __ CallRuntime(Runtime::kNotifyDeoptimized);
   }
 
-  // Get the full codegen state from the stack and untag it -> r9.
-  __ LoadP(r9, MemOperand(sp, 0 * kPointerSize));
-  __ SmiUntag(r9);
-  // Switch on the state.
-  Label with_tos_register, unknown_state;
-  __ cmpi(
-      r9,
-      Operand(static_cast<intptr_t>(Deoptimizer::BailoutState::NO_REGISTERS)));
-  __ bne(&with_tos_register);
-  __ addi(sp, sp, Operand(1 * kPointerSize));  // Remove state.
-  __ Ret();
-
-  __ bind(&with_tos_register);
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), r3.code());
-  __ LoadP(r3, MemOperand(sp, 1 * kPointerSize));
-  __ cmpi(
-      r9,
-      Operand(static_cast<intptr_t>(Deoptimizer::BailoutState::TOS_REGISTER)));
-  __ bne(&unknown_state);
-  __ addi(sp, sp, Operand(2 * kPointerSize));  // Remove state.
+  __ LoadP(r3, MemOperand(sp, 0 * kPointerSize));
+  __ addi(sp, sp, Operand(1 * kPointerSize));
   __ Ret();
-
-  __ bind(&unknown_state);
-  __ stop("no cases left");
 }
 
 static void Generate_OnStackReplacementHelper(MacroAssembler* masm,

src/builtins/s390/builtins-s390.cc

@@ -1525,7 +1525,6 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     __ pop(r2);
   }
 
-  __ AddP(sp, sp, Operand(kPointerSize));  // Ignore state
   __ Ret();                                // Jump to ContinueToBuiltin stub
 }
 
@@ -1587,30 +1586,9 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     __ CallRuntime(Runtime::kNotifyDeoptimized);
   }
 
-  // Get the full codegen state from the stack and untag it -> r8.
-  __ LoadP(r8, MemOperand(sp, 0 * kPointerSize));
-  __ SmiUntag(r8);
-  // Switch on the state.
-  Label with_tos_register, unknown_state;
-  __ CmpP(
-      r8,
-      Operand(static_cast<intptr_t>(Deoptimizer::BailoutState::NO_REGISTERS)));
-  __ bne(&with_tos_register);
-  __ la(sp, MemOperand(sp, 1 * kPointerSize));  // Remove state.
-  __ Ret();
-
-  __ bind(&with_tos_register);
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), r2.code());
-  __ LoadP(r2, MemOperand(sp, 1 * kPointerSize));
-  __ CmpP(
-      r8,
-      Operand(static_cast<intptr_t>(Deoptimizer::BailoutState::TOS_REGISTER)));
-  __ bne(&unknown_state);
-  __ la(sp, MemOperand(sp, 2 * kPointerSize));  // Remove state.
+  __ pop(r2);
   __ Ret();
-
-  __ bind(&unknown_state);
-  __ stop("no cases left");
 }
 
 static void Generate_OnStackReplacementHelper(MacroAssembler* masm,

src/builtins/x64/builtins-x64.cc

@@ -1540,7 +1540,6 @@ void Builtins::Generate_NotifyBuiltinContinuation(MacroAssembler* masm) {
     // Tear down internal frame.
   }
 
-  __ DropUnderReturnAddress(1);  // Ignore state offset
   __ ret(0);  // Return to ContinueToBuiltin stub still on stack.
 }
 
@@ -1603,26 +1602,9 @@ void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
     // Tear down internal frame.
   }
 
-  // Get the full codegen state from the stack and untag it.
-  __ SmiToInteger32(kScratchRegister, Operand(rsp, kPCOnStackSize));
-
-  // Switch on the state.
-  Label not_no_registers, not_tos_rax;
-  __ cmpp(kScratchRegister,
-          Immediate(static_cast<int>(Deoptimizer::BailoutState::NO_REGISTERS)));
-  __ j(not_equal, &not_no_registers, Label::kNear);
-  __ ret(1 * kPointerSize);  // Remove state.
-
-  __ bind(&not_no_registers);
   DCHECK_EQ(kInterpreterAccumulatorRegister.code(), rax.code());
-  __ movp(rax, Operand(rsp, kPCOnStackSize + kPointerSize));
-  __ cmpp(kScratchRegister,
-          Immediate(static_cast<int>(Deoptimizer::BailoutState::TOS_REGISTER)));
-  __ j(not_equal, &not_tos_rax, Label::kNear);
-  __ ret(2 * kPointerSize);  // Remove state, rax.
-
-  __ bind(&not_tos_rax);
-  __ Abort(kNoCasesLeft);
+  __ movp(rax, Operand(rsp, kPCOnStackSize));
+  __ ret(1 * kPointerSize);  // Remove rax.
 }
 
 // static

src/deoptimizer.cc

@@ -716,11 +716,9 @@ void Deoptimizer::DoComputeOutputFrames() {
     PrintFunctionName();
     PrintF(trace_scope_->file(),
            " @%d => node=%d, pc=0x%08" V8PRIxPTR ", caller sp=0x%08" V8PRIxPTR
-           ", state=%s, took %0.3f ms]\n",
+           ", took %0.3f ms]\n",
            bailout_id_, node_id.ToInt(), output_[index]->GetPc(),
-           caller_frame_top_, BailoutStateToString(static_cast<BailoutState>(
-                                  output_[index]->GetState()->value())),
-           ms);
+           caller_frame_top_, ms);
   }
 }
 
@@ -741,10 +739,11 @@ void Deoptimizer::DoComputeInterpretedFrame(TranslatedFrame* translated_frame,
       InterpreterFrameConstants::RegisterStackSlotCount(register_count);
   int height_in_bytes = register_stack_slot_count * kPointerSize;
 
-  // The topmost frame is assumed to be in bailout state
-  // {BailoutState::TOS_REGISTER} and will contain the accumulator, which we
-  // add to the frame height here.
-  if (is_topmost) height_in_bytes += kPointerSize;
+  // The topmost frame will contain the accumulator.
+  if (is_topmost) {
+    height_in_bytes += kPointerSize;
+    if (PadTopOfStackRegister()) height_in_bytes += kPointerSize;
+  }
 
   TranslatedFrame::iterator function_iterator = value_iterator;
   Object* function = value_iterator->GetRawValue();
@@ -939,9 +938,13 @@ void Deoptimizer::DoComputeInterpretedFrame(TranslatedFrame* translated_frame,
 
   // Translate the accumulator register (depending on frame position).
   if (is_topmost) {
-    // For topmost frame, put the accumulator on the stack. The bailout state
-    // for interpreted frames is always set to {BailoutState::TOS_REGISTER} and
-    // the {NotifyDeoptimized} builtin pops it off the topmost frame (possibly
+    if (PadTopOfStackRegister()) {
+      output_offset -= kPointerSize;
+      WriteValueToOutput(isolate()->heap()->the_hole_value(), 0, frame_index,
+                         output_offset, "padding ");
+    }
+    // For topmost frame, put the accumulator on the stack. The
+    // {NotifyDeoptimized} builtin pops it off the topmost frame (possibly
     // after materialization).
     output_offset -= kPointerSize;
     if (goto_catch_handler) {
@@ -974,9 +977,6 @@ void Deoptimizer::DoComputeInterpretedFrame(TranslatedFrame* translated_frame,
           ? builtins->builtin(Builtins::kInterpreterEnterBytecodeAdvance)
           : builtins->builtin(Builtins::kInterpreterEnterBytecodeDispatch);
   output_frame->SetPc(reinterpret_cast<intptr_t>(dispatch_builtin->entry()));
-  // Restore accumulator (TOS) register.
-  output_frame->SetState(
-      Smi::FromInt(static_cast<int>(BailoutState::TOS_REGISTER)));
 
   // Update constant pool.
   if (FLAG_enable_embedded_constant_pool) {
@@ -1153,10 +1153,11 @@ void Deoptimizer::DoComputeConstructStubFrame(TranslatedFrame* translated_frame,
   // If the construct frame appears to be topmost we should ensure that the
   // value of result register is preserved during continuation execution.
   // We do this here by "pushing" the result of the constructor function to the
-  // top of the reconstructed stack and then using the
-  // BailoutState::TOS_REGISTER machinery.
+  // top of the reconstructed stack and popping it in
+  // {Builtins::kNotifyDeoptimized}.
   if (is_topmost) {
     height_in_bytes += kPointerSize;
+    if (PadTopOfStackRegister()) height_in_bytes += kPointerSize;
   }
 
   JSFunction* function = JSFunction::cast(value_iterator->GetRawValue());
@@ -1271,15 +1272,17 @@ void Deoptimizer::DoComputeConstructStubFrame(TranslatedFrame* translated_frame,
   }
 
   if (is_topmost) {
+    if (PadTopOfStackRegister()) {
+      output_offset -= kPointerSize;
+      WriteValueToOutput(isolate()->heap()->the_hole_value(), 0, frame_index,
+                         output_offset, "padding ");
+    }
     // Ensure the result is restored back when we return to the stub.
     output_offset -= kPointerSize;
     Register result_reg = kReturnRegister0;
     value = input_->GetRegister(result_reg.code());
     output_frame->SetFrameSlot(output_offset, value);
     DebugPrintOutputSlot(value, frame_index, output_offset, "subcall result\n");
-
-    output_frame->SetState(
-        Smi::FromInt(static_cast<int>(BailoutState::TOS_REGISTER)));
   }
 
   CHECK_EQ(0u, output_offset);
@@ -1348,13 +1351,14 @@ void Deoptimizer::DoComputeAccessorStubFrame(TranslatedFrame* translated_frame,
   // If the accessor frame appears to be topmost we should ensure that the
   // value of result register is preserved during continuation execution.
   // We do this here by "pushing" the result of the accessor function to the
-  // top of the reconstructed stack and then using the
-  // BailoutState::TOS_REGISTER machinery.
-  // We don't need to restore the result in case of a setter call because we
-  // have to return the stored value but not the result of the setter function.
-  bool should_preserve_result = is_topmost && !is_setter_stub_frame;
-  if (should_preserve_result) {
+  // top of the reconstructed stack and then popping it in
+  // {Builtins::kNotifyDeoptimized}.
+  // For setter calls, since the result register is going to be overwritten
+  // anyway in the stub, we store a dummy value to pop into the result register
+  // to keep the code simpler.
+  if (is_topmost) {
     height_in_bytes += kPointerSize;
+    if (PadTopOfStackRegister()) height_in_bytes += kPointerSize;
   }
 
   const char* kind = is_setter_stub_frame ? "setter" : "getter";
@@ -1454,7 +1458,12 @@ void Deoptimizer::DoComputeAccessorStubFrame(TranslatedFrame* translated_frame,
                                  output_offset);
   }
 
-  if (should_preserve_result) {
+  if (is_topmost) {
+    if (PadTopOfStackRegister()) {
+      output_offset -= kPointerSize;
+      WriteValueToOutput(isolate()->heap()->the_hole_value(), 0, frame_index,
+                         output_offset, "padding ");
+    }
     // Ensure the result is restored back when we return to the stub.
     output_offset -= kPointerSize;
     Register result_reg = kReturnRegister0;
@@ -1462,12 +1471,6 @@ void Deoptimizer::DoComputeAccessorStubFrame(TranslatedFrame* translated_frame,
     output_frame->SetFrameSlot(output_offset, value);
     DebugPrintOutputSlot(value, frame_index, output_offset,
                          "accessor result\n");
-
-    output_frame->SetState(
-        Smi::FromInt(static_cast<int>(BailoutState::TOS_REGISTER)));
-  } else {
-    output_frame->SetState(
-        Smi::FromInt(static_cast<int>(BailoutState::NO_REGISTERS)));
   }
 
   CHECK_EQ(0u, output_offset);
@@ -1630,9 +1633,6 @@ void Deoptimizer::DoComputeBuiltinContinuation(
   }
   output_frame->SetTop(top_address);
 
-  output_frame->SetState(
-      Smi::FromInt(static_cast<int>(BailoutState::NO_REGISTERS)));
-
   // Get the possible JSFunction for the case that
   intptr_t maybe_function =
       reinterpret_cast<intptr_t>(value_iterator->GetRawValue());

src/deoptimizer.h

@@ -326,21 +326,6 @@ class Deoptimizer : public Malloced {
  public:
   enum BailoutType { EAGER, LAZY, SOFT, kLastBailoutType = SOFT };
 
-  enum class BailoutState {
-    NO_REGISTERS,
-    TOS_REGISTER,
-  };
-
-  static const char* BailoutStateToString(BailoutState state) {
-    switch (state) {
-      case BailoutState::NO_REGISTERS:
-        return "NO_REGISTERS";
-      case BailoutState::TOS_REGISTER:
-        return "TOS_REGISTER";
-    }
-    UNREACHABLE();
-  }
-
   struct DeoptInfo {
     DeoptInfo(SourcePosition position, DeoptimizeReason deopt_reason,
               int deopt_id)
@@ -537,6 +522,10 @@ class Deoptimizer : public Malloced {
   // Deoptimizes all code marked in the given context.
   static void DeoptimizeMarkedCodeForContext(Context* native_context);
 
+  // Some architectures need to push padding together with the TOS register
+  // in order to maintain stack alignment.
+  static bool PadTopOfStackRegister();
+
   // Searches the list of known deoptimizing code for a Code object
   // containing the given address (which is supposedly faster than
   // searching all code objects).
@@ -722,9 +711,6 @@ class FrameDescription {
     constant_pool_ = constant_pool;
   }
 
-  Smi* GetState() const { return state_; }
-  void SetState(Smi* state) { state_ = state; }
-
   void SetContinuation(intptr_t pc) { continuation_ = pc; }
 
   // Argument count, including receiver.
@@ -748,8 +734,6 @@ class FrameDescription {
 
   static int pc_offset() { return offsetof(FrameDescription, pc_); }
 
-  static int state_offset() { return offsetof(FrameDescription, state_); }
-
   static int continuation_offset() {
     return offsetof(FrameDescription, continuation_);
   }
@@ -772,7 +756,6 @@ class FrameDescription {
   intptr_t fp_;
   intptr_t context_;
   intptr_t constant_pool_;
-  Smi* state_;
 
   // Continuation is the PC where the execution continues after
   // deoptimizing.

src/ia32/deoptimizer-ia32.cc

@@ -184,12 +184,10 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ movsd(xmm_reg, Operand(ebx, src_offset));
   }
 
-  // Push state, pc, and continuation from the last output frame.
-  __ push(Operand(ebx, FrameDescription::state_offset()));
+  // Push pc and continuation from the last output frame.
   __ push(Operand(ebx, FrameDescription::pc_offset()));
   __ push(Operand(ebx, FrameDescription::continuation_offset()));
 
-
   // Push the registers from the last output frame.
   for (int i = 0; i < kNumberOfRegisters; i++) {
     int offset = (i * kPointerSize) + FrameDescription::registers_offset();
@@ -217,6 +215,7 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   __ bind(&done);
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return false; }
 
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);

src/mips/deoptimizer-mips.cc

@@ -209,10 +209,7 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ Ldc1(fpu_reg, MemOperand(a1, src_offset));
   }
 
-  // Push state, pc, and continuation from the last output frame.
-  __ lw(t2, MemOperand(a2, FrameDescription::state_offset()));
-  __ push(t2);
-
+  // Push pc and continuation from the last output frame.
   __ lw(t2, MemOperand(a2, FrameDescription::pc_offset()));
   __ push(t2);
   __ lw(t2, MemOperand(a2, FrameDescription::continuation_offset()));
@@ -314,6 +311,7 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   }
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return false; }
 
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);

src/mips64/deoptimizer-mips64.cc

@@ -208,16 +208,12 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ Ldc1(fpu_reg, MemOperand(a1, src_offset));
   }
 
-  // Push state, pc, and continuation from the last output frame.
-  __ Ld(a6, MemOperand(a2, FrameDescription::state_offset()));
-  __ push(a6);
-
+  // Push pc and continuation from the last output frame.
   __ Ld(a6, MemOperand(a2, FrameDescription::pc_offset()));
   __ push(a6);
   __ Ld(a6, MemOperand(a2, FrameDescription::continuation_offset()));
   __ push(a6);
 
-
   // Technically restoring 'at' should work unless zero_reg is also restored
   // but it's safer to check for this.
   DCHECK(!(at.bit() & restored_regs));
@@ -313,6 +309,7 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   }
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return false; }
 
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);

src/ppc/deoptimizer-ppc.cc

@@ -204,9 +204,7 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ lfd(dreg, MemOperand(r4, src_offset));
   }
 
-  // Push state, pc, and continuation from the last output frame.
-  __ LoadP(r9, MemOperand(r5, FrameDescription::state_offset()));
-  __ push(r9);
+  // Push pc, and continuation from the last output frame.
   __ LoadP(r9, MemOperand(r5, FrameDescription::pc_offset()));
   __ push(r9);
   __ LoadP(r9, MemOperand(r5, FrameDescription::continuation_offset()));
@@ -249,6 +247,7 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   __ push(ip);
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return false; }
 
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);

src/s390/deoptimizer-s390.cc

@@ -211,9 +211,7 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ ld(dreg, MemOperand(r3, src_offset));
   }
 
-  // Push state, pc, and continuation from the last output frame.
-  __ LoadP(r8, MemOperand(r4, FrameDescription::state_offset()));
-  __ push(r8);
+  // Push pc and continuation from the last output frame.
   __ LoadP(r8, MemOperand(r4, FrameDescription::pc_offset()));
   __ push(r8);
   __ LoadP(r8, MemOperand(r4, FrameDescription::continuation_offset()));
@@ -254,6 +252,8 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   __ StoreP(ip, MemOperand(sp));
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return false; }
+
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);
 }

src/x64/deoptimizer-x64.cc

@@ -196,8 +196,7 @@ void Deoptimizer::TableEntryGenerator::Generate() {
     __ Movsd(xmm_reg, Operand(rbx, src_offset));
   }
 
-  // Push state, pc, and continuation from the last output frame.
-  __ Push(Operand(rbx, FrameDescription::state_offset()));
+  // Push pc and continuation from the last output frame.
   __ PushQuad(Operand(rbx, FrameDescription::pc_offset()));
   __ PushQuad(Operand(rbx, FrameDescription::continuation_offset()));
 
@@ -240,6 +239,7 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
   __ bind(&done);
 }
 
+bool Deoptimizer::PadTopOfStackRegister() { return false; }
 
 void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
   if (kPCOnStackSize == 2 * kPointerSize) {