ARM: Track Smis on top 4 stack positions and Smi loop variables.

Improve code generation for known smis and suspected Smis.
Review URL: http://codereview.chromium.org/2452002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4783 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/codegen-arm.h

@@ -43,6 +43,7 @@ class RegisterFile;
 
 enum InitState { CONST_INIT, NOT_CONST_INIT };
 enum TypeofState { INSIDE_TYPEOF, NOT_INSIDE_TYPEOF };
+enum GenerateInlineSmi { DONT_GENERATE_INLINE_SMI, GENERATE_INLINE_SMI };
 
 
 // -------------------------------------------------------------------------
@@ -129,24 +130,55 @@ class CodeGenState BASE_EMBEDDED {
   // leaves the code generator with a NULL state.
   explicit CodeGenState(CodeGenerator* owner);
 
+  // Destroy a code generator state and restore the owning code generator's
+  // previous state.
+  virtual ~CodeGenState();
+
+  virtual JumpTarget* true_target() const { return NULL; }
+  virtual JumpTarget* false_target() const { return NULL; }
+
+ protected:
+  inline CodeGenerator* owner() { return owner_; }
+  inline CodeGenState* previous() const { return previous_; }
+
+ private:
+  CodeGenerator* owner_;
+  CodeGenState* previous_;
+};
+
+
+class ConditionCodeGenState : public CodeGenState {
+ public:
   // Create a code generator state based on a code generator's current
   // state.  The new state has its own pair of branch labels.
-  CodeGenState(CodeGenerator* owner,
+  ConditionCodeGenState(CodeGenerator* owner,
                         JumpTarget* true_target,
                         JumpTarget* false_target);
 
-  // Destroy a code generator state and restore the owning code generator's
-  // previous state.
-  ~CodeGenState();
-
-  JumpTarget* true_target() const { return true_target_; }
-  JumpTarget* false_target() const { return false_target_; }
+  virtual JumpTarget* true_target() const { return true_target_; }
+  virtual JumpTarget* false_target() const { return false_target_; }
 
  private:
-  CodeGenerator* owner_;
   JumpTarget* true_target_;
   JumpTarget* false_target_;
-  CodeGenState* previous_;
+};
+
+
+class TypeInfoCodeGenState : public CodeGenState {
+ public:
+  TypeInfoCodeGenState(CodeGenerator* owner,
+                       Slot* slot_number,
+                       TypeInfo info);
+  ~TypeInfoCodeGenState();
+
+  virtual JumpTarget* true_target() const { return previous()->true_target(); }
+  virtual JumpTarget* false_target() const {
+    return previous()->false_target();
+  }
+
+ private:
+  Slot* slot_;
+  TypeInfo old_type_info_;
 };
 
 
@@ -216,6 +248,23 @@ class CodeGenerator: public AstVisitor {
   CodeGenState* state() { return state_; }
   void set_state(CodeGenState* state) { state_ = state; }
 
+  TypeInfo type_info(Slot* slot) {
+    int index = NumberOfSlot(slot);
+    if (index == kInvalidSlotNumber) return TypeInfo::Unknown();
+    return (*type_info_)[index];
+  }
+
+  TypeInfo set_type_info(Slot* slot, TypeInfo info) {
+    int index = NumberOfSlot(slot);
+    ASSERT(index >= kInvalidSlotNumber);
+    if (index != kInvalidSlotNumber) {
+      TypeInfo previous_value = (*type_info_)[index];
+      (*type_info_)[index] = info;
+      return previous_value;
+    }
+    return TypeInfo::Unknown();
+  }
+
   void AddDeferred(DeferredCode* code) { deferred_.Add(code); }
 
   static const int kUnknownIntValue = -1;
@@ -225,7 +274,7 @@ class CodeGenerator: public AstVisitor {
   static int InlineRuntimeCallArgumentsCount(Handle<String> name);
 
   // Constants related to patching of inlined load/store.
-  static const int kInlinedKeyedLoadInstructionsAfterPatch = 19;
+  static const int kInlinedKeyedLoadInstructionsAfterPatch = 17;
   static const int kInlinedKeyedStoreInstructionsAfterPatch = 5;
 
  private:
@@ -239,6 +288,10 @@ class CodeGenerator: public AstVisitor {
   // Generating deferred code.
   void ProcessDeferred();
 
+  static const int kInvalidSlotNumber = -1;
+
+  int NumberOfSlot(Slot* slot);
+
   // State
   bool has_cc() const  { return cc_reg_ != al; }
   JumpTarget* true_target() const  { return state_->true_target(); }
@@ -351,9 +404,7 @@ class CodeGenerator: public AstVisitor {
 
   void GenericBinaryOperation(Token::Value op,
                               OverwriteMode overwrite_mode,
-                              int known_rhs = kUnknownIntValue);
-  void VirtualFrameBinaryOperation(Token::Value op,
-                                   OverwriteMode overwrite_mode,
+                              GenerateInlineSmi inline_smi,
                               int known_rhs = kUnknownIntValue);
   void Comparison(Condition cc,
                   Expression* left,
@@ -511,6 +562,8 @@ class CodeGenerator: public AstVisitor {
   CodeGenState* state_;
   int loop_nesting_;
 
+  Vector<TypeInfo>* type_info_;
+
   // Jump targets
   BreakTarget function_return_;
 

src/arm/jump-target-arm.cc

@@ -50,6 +50,11 @@ void JumpTarget::DoJump() {
   ASSERT(cgen()->HasValidEntryRegisters());
 
   if (entry_frame_set_) {
+    if (entry_label_.is_bound()) {
+      // If we already bound and generated code at the destination then it
+      // is too late to ask for less optimistic type assumptions.
+      ASSERT(entry_frame_.IsCompatibleWith(cgen()->frame()));
+    }
     // There already a frame expectation at the target.
     cgen()->frame()->MergeTo(&entry_frame_);
     cgen()->DeleteFrame();
@@ -67,8 +72,12 @@ void JumpTarget::DoBranch(Condition cc, Hint ignored) {
   ASSERT(cgen()->has_valid_frame());
 
   if (entry_frame_set_) {
-    // Backward branch.  We have an expected frame to merge to on the
-    // backward edge.
+    if (entry_label_.is_bound()) {
+      // If we already bound and generated code at the destination then it
+      // is too late to ask for less optimistic type assumptions.
+      ASSERT(entry_frame_.IsCompatibleWith(cgen()->frame()));
+    }
+    // We have an expected frame to merge to on the backward edge.
     cgen()->frame()->MergeTo(&entry_frame_, cc);
   } else {
     // Clone the current frame to use as the expected one at the target.

src/arm/virtual-frame-arm-inl.h

@@ -48,6 +48,12 @@ MemOperand VirtualFrame::Receiver() {
   return ParameterAt(-1);
 }
 
+
+void VirtualFrame::Forget(int count) {
+  SpillAll();
+  LowerHeight(count);
+}
+
 } }  // namespace v8::internal
 
 #endif  // V8_VIRTUAL_FRAME_ARM_INL_H_

src/arm/virtual-frame-arm.cc

@@ -43,7 +43,7 @@ void VirtualFrame::PopToR1R0() {
   // Shuffle things around so the top of stack is in r0 and r1.
   MergeTOSTo(R0_R1_TOS);
   // Pop the two registers off the stack so they are detached from the frame.
-  element_count_ -= 2;
+  LowerHeight(2);
   top_of_stack_state_ = NO_TOS_REGISTERS;
 }
 
@@ -52,7 +52,7 @@ void VirtualFrame::PopToR1() {
   // Shuffle things around so the top of stack is only in r1.
   MergeTOSTo(R1_TOS);
   // Pop the register off the stack so it is detached from the frame.
-  element_count_ -= 1;
+  LowerHeight(1);
   top_of_stack_state_ = NO_TOS_REGISTERS;
 }
 
@@ -61,13 +61,22 @@ void VirtualFrame::PopToR0() {
   // Shuffle things around so the top of stack only in r0.
   MergeTOSTo(R0_TOS);
   // Pop the register off the stack so it is detached from the frame.
-  element_count_ -= 1;
+  LowerHeight(1);
   top_of_stack_state_ = NO_TOS_REGISTERS;
 }
 
 
 void VirtualFrame::MergeTo(const VirtualFrame* expected, Condition cond) {
   if (Equals(expected)) return;
+  ASSERT(expected->IsCompatibleWith(this));
+  MergeTOSTo(expected->top_of_stack_state_, cond);
+  ASSERT(register_allocation_map_ == expected->register_allocation_map_);
+}
+
+
+void VirtualFrame::MergeTo(VirtualFrame* expected, Condition cond) {
+  if (Equals(expected)) return;
+  expected->tos_known_smi_map_ &= tos_known_smi_map_;
   MergeTOSTo(expected->top_of_stack_state_, cond);
   ASSERT(register_allocation_map_ == expected->register_allocation_map_);
 }
@@ -420,7 +429,7 @@ void VirtualFrame::Drop(int count) {
   }
   if (count == 0) return;
   __ add(sp, sp, Operand(count * kPointerSize));
-  element_count_ -= count;
+  LowerHeight(count);
 }
 
 
@@ -430,7 +439,7 @@ void VirtualFrame::Pop() {
   } else {
     top_of_stack_state_ = kStateAfterPop[top_of_stack_state_];
   }
-  element_count_--;
+  LowerHeight(1);
 }
 
 
@@ -442,7 +451,7 @@ void VirtualFrame::EmitPop(Register reg) {
     __ mov(reg, kTopRegister[top_of_stack_state_]);
     top_of_stack_state_ = kStateAfterPop[top_of_stack_state_];
   }
-  element_count_--;
+  LowerHeight(1);
 }
 
 
@@ -550,7 +559,7 @@ void VirtualFrame::Dup() {
         UNREACHABLE();
     }
   }
-  element_count_++;
+  RaiseHeight(1, tos_known_smi_map_ & 1);
 }
 
 
@@ -589,7 +598,7 @@ void VirtualFrame::Dup2() {
         UNREACHABLE();
     }
   }
-  element_count_ += 2;
+  RaiseHeight(2, tos_known_smi_map_ & 3);
 }
 
 
@@ -597,7 +606,7 @@ Register VirtualFrame::PopToRegister(Register but_not_to_this_one) {
   ASSERT(but_not_to_this_one.is(r0) ||
          but_not_to_this_one.is(r1) ||
          but_not_to_this_one.is(no_reg));
-  element_count_--;
+  LowerHeight(1);
   if (top_of_stack_state_ == NO_TOS_REGISTERS) {
     if (but_not_to_this_one.is(r0)) {
       __ pop(r1);
@@ -625,8 +634,8 @@ void VirtualFrame::EnsureOneFreeTOSRegister() {
 }
 
 
-void VirtualFrame::EmitPush(Register reg) {
-  element_count_++;
+void VirtualFrame::EmitPush(Register reg, TypeInfo info) {
+  RaiseHeight(1, info.IsSmi() ? 1 : 0);
   if (reg.is(cp)) {
     // If we are pushing cp then we are about to make a call and things have to
     // be pushed to the physical stack.  There's nothing to be gained my moving
@@ -659,6 +668,9 @@ void VirtualFrame::EmitPush(Register reg) {
 
 
 void VirtualFrame::SetElementAt(Register reg, int this_far_down) {
+  if (this_far_down < kTOSKnownSmiMapSize) {
+    tos_known_smi_map_ &= ~(1 << this_far_down);
+  }
   if (this_far_down == 0) {
     Pop();
     Register dest = GetTOSRegister();
@@ -699,8 +711,8 @@ Register VirtualFrame::GetTOSRegister() {
 }
 
 
-void VirtualFrame::EmitPush(Operand operand) {
-  element_count_++;
+void VirtualFrame::EmitPush(Operand operand, TypeInfo info) {
+  RaiseHeight(1, info.IsSmi() ? 1 : 0);
   if (SpilledScope::is_spilled()) {
     __ mov(r0, operand);
     __ push(r0);
@@ -712,8 +724,8 @@ void VirtualFrame::EmitPush(Operand operand) {
 }
 
 
-void VirtualFrame::EmitPush(MemOperand operand) {
-  element_count_++;
+void VirtualFrame::EmitPush(MemOperand operand, TypeInfo info) {
+  RaiseHeight(1, info.IsSmi() ? 1 : 0);
   if (SpilledScope::is_spilled()) {
     __ ldr(r0, operand);
     __ push(r0);
@@ -726,7 +738,7 @@ void VirtualFrame::EmitPush(MemOperand operand) {
 
 
 void VirtualFrame::EmitPushRoot(Heap::RootListIndex index) {
-  element_count_++;
+  RaiseHeight(1, 0);
   if (SpilledScope::is_spilled()) {
     __ LoadRoot(r0, index);
     __ push(r0);

src/arm/virtual-frame-arm.h

@@ -154,10 +154,7 @@ class VirtualFrame : public ZoneObject {
   // Forget elements from the top of the frame to match an actual frame (eg,
   // the frame after a runtime call).  No code is emitted except to bring the
   // frame to a spilled state.
-  void Forget(int count) {
-    SpillAll();
-    element_count_ -= count;
-  }
+  void Forget(int count);
 
   // Spill all values from the frame to memory.
   void SpillAll();
@@ -184,8 +181,14 @@ class VirtualFrame : public ZoneObject {
   // Make this virtual frame have a state identical to an expected virtual
   // frame.  As a side effect, code may be emitted to make this frame match
   // the expected one.
+  void MergeTo(VirtualFrame* expected, Condition cond = al);
   void MergeTo(const VirtualFrame* expected, Condition cond = al);
 
+  // Checks whether this frame can be branched to by the other frame.
+  bool IsCompatibleWith(const VirtualFrame* other) const {
+    return (tos_known_smi_map_ & (~other->tos_known_smi_map_)) == 0;
+  }
+
   // Detach a frame from its code generator, perhaps temporarily.  This
   // tells the register allocator that it is free to use frame-internal
   // registers.  Used when the code generator's frame is switched from this
@@ -234,6 +237,11 @@ class VirtualFrame : public ZoneObject {
     return MemOperand(sp, adjusted_index * kPointerSize);
   }
 
+  bool KnownSmiAt(int index) {
+    if (index >= kTOSKnownSmiMapSize) return false;
+    return (tos_known_smi_map_ & (1 << index)) != 0;
+  }
+
   // A frame-allocated local as an assembly operand.
   inline MemOperand LocalAt(int index);
 
@@ -352,9 +360,9 @@ class VirtualFrame : public ZoneObject {
 
   // Push an element on top of the expression stack and emit a
   // corresponding push instruction.
-  void EmitPush(Register reg);
-  void EmitPush(Operand operand);
-  void EmitPush(MemOperand operand);
+  void EmitPush(Register reg, TypeInfo type_info = TypeInfo::Unknown());
+  void EmitPush(Operand operand, TypeInfo type_info = TypeInfo::Unknown());
+  void EmitPush(MemOperand operand, TypeInfo type_info = TypeInfo::Unknown());
   void EmitPushRoot(Heap::RootListIndex index);
 
   // Overwrite the nth thing on the stack.  If the nth position is in a
@@ -419,6 +427,8 @@ class VirtualFrame : public ZoneObject {
   int element_count_;
   TopOfStack top_of_stack_state_:3;
   int register_allocation_map_:kNumberOfAllocatedRegisters;
+  static const int kTOSKnownSmiMapSize = 4;
+  unsigned tos_known_smi_map_:kTOSKnownSmiMapSize;
 
   // The index of the element that is at the processor's stack pointer
   // (the sp register).  For now since everything is in memory it is given
@@ -473,6 +483,25 @@ class VirtualFrame : public ZoneObject {
 
   inline bool Equals(const VirtualFrame* other);
 
+  inline void LowerHeight(int count) {
+    element_count_ -= count;
+    if (count >= kTOSKnownSmiMapSize) {
+      tos_known_smi_map_ = 0;
+    } else {
+      tos_known_smi_map_ >>= count;
+    }
+  }
+
+  inline void RaiseHeight(int count, unsigned known_smi_map = 0) {
+    ASSERT(known_smi_map < (1u << count));
+    element_count_ += count;
+    if (count >= kTOSKnownSmiMapSize) {
+      tos_known_smi_map_ = known_smi_map;
+    } else {
+      tos_known_smi_map_ = ((tos_known_smi_map_ << count) | known_smi_map);
+    }
+  }
+
   friend class JumpTarget;
 };
 

src/data-flow.cc

@@ -318,6 +318,9 @@ Variable* AssignedVariablesAnalyzer::FindSmiLoopVariable(ForStatement* stmt) {
   Variable* loop_var = init->target()->AsVariableProxy()->AsVariable();
   if (loop_var == NULL || !loop_var->IsStackAllocated()) return NULL;
 
+  // Don't try to get clever with const or dynamic variables.
+  if (loop_var->mode() != Variable::VAR) return NULL;
+
   // The initial value has to be a smi.
   Literal* init_lit = init->value()->AsLiteral();
   if (init_lit == NULL || !init_lit->handle()->IsSmi()) return NULL;

src/type-info.h

@@ -47,7 +47,7 @@ namespace internal {
 
 class TypeInfo {
  public:
-  TypeInfo() { }
+  TypeInfo() : type_(kUnknownType) { }
 
   static inline TypeInfo Unknown();
   // We know it's a primitive type.

src/virtual-frame-light-inl.h

@@ -42,7 +42,8 @@ namespace internal {
 VirtualFrame::VirtualFrame(InvalidVirtualFrameInitializer* dummy)
     : element_count_(0),
       top_of_stack_state_(NO_TOS_REGISTERS),
-      register_allocation_map_(0) { }
+      register_allocation_map_(0),
+      tos_known_smi_map_(0) { }
 
 
 // On entry to a function, the virtual frame already contains the receiver,
@@ -50,20 +51,23 @@ VirtualFrame::VirtualFrame(InvalidVirtualFrameInitializer* dummy)
 VirtualFrame::VirtualFrame()
     : element_count_(parameter_count() + 2),
       top_of_stack_state_(NO_TOS_REGISTERS),
-      register_allocation_map_(0) { }
+      register_allocation_map_(0),
+      tos_known_smi_map_(0) { }
 
 
 // When cloned, a frame is a deep copy of the original.
 VirtualFrame::VirtualFrame(VirtualFrame* original)
     : element_count_(original->element_count()),
       top_of_stack_state_(original->top_of_stack_state_),
-      register_allocation_map_(original->register_allocation_map_) { }
+      register_allocation_map_(original->register_allocation_map_),
+      tos_known_smi_map_(0) { }
 
 
 bool VirtualFrame::Equals(const VirtualFrame* other) {
   ASSERT(element_count() == other->element_count());
   if (top_of_stack_state_ != other->top_of_stack_state_) return false;
   if (register_allocation_map_ != other->register_allocation_map_) return false;
+  if (tos_known_smi_map_ != other->tos_known_smi_map_) return false;
 
   return true;
 }

src/virtual-frame-light.cc

@@ -36,7 +36,7 @@ namespace internal {
 
 void VirtualFrame::Adjust(int count) {
   ASSERT(count >= 0);
-  element_count_ += count;
+  RaiseHeight(count, 0);
 }