Optionally use 31-bits SMI value for 64-bit system

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index ca13ca3955423c54f3bcc5136186b4adc9ba3600..44782265d54b33cded38e701949c5048f0a01956 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -375,6 +375,18 @@ class MacroAssembler: public Assembler {
   // ---------------------------------------------------------------------------
   // Smi tagging, untagging and operations on tagged smis.
 
+  class SmiFunctionInvoker {

[danno, 2013/08/07 18:41:26]

I think approach works, but I think you can get away with a single virtual
method on the abstract super class (which should just be called ValidSmiChecker
or something like that)

virtual void DoCheckSmi(Register smi_candidate_reg);

Then you have two subclasses, LithiumValidSmiChecker that takes the LCodeGen and
environment in its constructor and implements it so:

virtual void DoCheckSmi(Register smi_candidate_reg) {
  if (kSmiSize == 31) {
    cmpl(src, Immediate(0xc0000000));
    code_gen()->DeoptimizeIf(zero, environment());
  }
 }

And stub generators/full code gen take a label in their constructor:

virtual void DoCheckSmi(Register smi_candidate_reg) {
  if (kSmiSize == 31) {
    cmpl(src, Immediate(0xc0000000));
    b(zero, fail_label());
  }
 }

}

 

[haitao.feng, 2013/08/12 09:54:24]

Thanks for the recommendation. I used a slightly different version:

  class SmiInstructionWrapper {                                                 
   public:                                                                      
    SmiInstructionWrapper() { }                                                 
    virtual ~SmiInstructionWrapper() { }                                        
    virtual bool NeedsCheckOverflow() const = 0;                                
    virtual bool NeedsCheckMinusZero() const = 0;                               
    virtual bool NeedsKeepSourceOperandsIntact() const = 0;                     
    virtual void BailoutIf(Condition cc) const = 0;                             
  };                                                                            

It seems that BailoutIf(Condition cc) is more generally. I have used it to
handle SmiShiftLeftConstant, SmiAdd and SmiSub. It should be able to handle
SmiMul (a work in progress at https://codereview.chromium.org/22600005/).

+   public:
+    explicit SmiFunctionInvoker(Label* label) : label_(label) { }
+    virtual ~SmiFunctionInvoker() { }
+    virtual void Bailout() { }
+    virtual Label* on_not_smi_result() { return label_; }
+    virtual bool reserve_source_operands() { return true; }
+    virtual bool check_minus_zero() { return true; }
+   private:
+    Label* label_;
+  };
+
   void InitializeSmiConstantRegister() {
     movq(kSmiConstantRegister,
          reinterpret_cast<uint64_t>(Smi::FromInt(kSmiConstantRegisterValue)),
@@ -484,10 +496,17 @@ class MacroAssembler: public Assembler {
   // Jump if the value cannot be represented by a smi.
   void JumpIfNotValidSmiValue(Register src, Label* on_invalid,
                               Label::Distance near_jump = Label::kFar);
+  // Jump if the value can be represented by a smi.
+  void JumpIfValidSmiValue(Register src, Label* on_valid,
+                           Label::Distance near_jump = Label::kFar);
 
   // Jump if the unsigned integer value cannot be represented by a smi.
   void JumpIfUIntNotValidSmiValue(Register src, Label* on_invalid,
                                   Label::Distance near_jump = Label::kFar);
+  // Jump if the unsigned integer value can be represented by a smi.
+  void JumpIfUIntValidSmiValue(Register src, Label* on_valid,
+                               Label::Distance near_jump = Label::kFar);
+
 
   // Jump to label if the value is a tagged smi.
   void JumpIfSmi(Register src,
@@ -650,7 +669,8 @@ class MacroAssembler: public Assembler {
 
   void SmiShiftLeftConstant(Register dst,
                             Register src,
-                            int shift_value);
+                            int shift_value,
+                            SmiFunctionInvoker& env);
   void SmiShiftLogicalRightConstant(Register dst,
                                   Register src,
                                   int shift_value,
@@ -664,7 +684,8 @@ class MacroAssembler: public Assembler {
   // Uses and clobbers rcx, so dst may not be rcx.
   void SmiShiftLeft(Register dst,
                     Register src1,
-                    Register src2);
+                    Register src2,
+                    Label* on_not_smi_result);
   // Shifts a smi value to the right, shifting in zero bits at the top, and
   // returns the unsigned intepretation of the result if that is a smi.
   // Uses and clobbers rcx, so dst may not be rcx.
@@ -722,6 +743,9 @@ class MacroAssembler: public Assembler {
   void Push(Smi* smi);
   void Test(const Operand& dst, Smi* source);
 
+  void PushInt64AsTwoSmis(Register src, Register scratch = kScratchRegister);
+  void PopInt64AsTwoSmis(Register dst, Register scratch = kScratchRegister);
+  static bool IsUnsafeSmiOperator(Token::Value op);
 
   // ---------------------------------------------------------------------------
   // String macros.