Make x87 stack tracking more robust and avoid spilling

src/ia32/lithium-codegen-ia32.h

Index: src/ia32/lithium-codegen-ia32.h
diff --git a/src/ia32/lithium-codegen-ia32.h b/src/ia32/lithium-codegen-ia32.h
index 5a474b67f64723339607be28393f25ca7e768464..470998ab1482ce2565e469e1e4415cce900b57b4 100644
--- a/src/ia32/lithium-codegen-ia32.h
+++ b/src/ia32/lithium-codegen-ia32.h
@@ -52,7 +52,7 @@ class LCodeGen V8_FINAL BASE_EMBEDDED {
         chunk_(static_cast<LPlatformChunk*>(chunk)),
         masm_(assembler),
         info_(info),
-        current_block_(-1),
+        current_block_(NULL),
         current_instruction_(-1),
         instructions_(chunk->instructions()),
         deoptimizations_(4, info->zone()),
@@ -120,6 +120,7 @@ class LCodeGen V8_FINAL BASE_EMBEDDED {
   // virtual registers between instructions.
   enum X87OperandType { kX87DoubleOperand, kX87FloatOperand, kX87IntOperand };
 
+  void X87Mov(X87Register reg, X87Register src);
   void X87Mov(X87Register reg, Operand src,
       X87OperandType operand = kX87DoubleOperand);
   void X87Mov(Operand src, X87Register reg,
@@ -414,6 +415,11 @@ class LCodeGen V8_FINAL BASE_EMBEDDED {
   void FlushX87StackIfNecessary(LInstruction* instr) {
     x87_stack_.FlushIfNecessary(instr, this);
   }
+  void RestoreX87StackIfNecessary(LInstruction* instr) {
+    x87_stack_.RestoreIfNecessary(instr, this);
+  }
+  void PreRecordX87StackUsage();
+
   friend class LGapResolver;
 
 #ifdef _MSC_VER
@@ -429,7 +435,7 @@ class LCodeGen V8_FINAL BASE_EMBEDDED {
   MacroAssembler* const masm_;
   CompilationInfo* const info_;
 
-  int current_block_;
+  HBasicBlock* current_block_;
   int current_instruction_;
   const ZoneList<LInstruction*>* instructions_;
   ZoneList<LEnvironment*> deoptimizations_;
@@ -448,41 +454,41 @@ class LCodeGen V8_FINAL BASE_EMBEDDED {
 
   class X87Stack {
    public:
-    explicit X87Stack(MacroAssembler* masm) : stack_depth_(0), masm_(masm) { }
-    explicit X87Stack(const X87Stack& other)
-        : stack_depth_(0), masm_(other.masm_) {
-      stack_depth_ = other.stack_depth_;
-      for (int i = 0; i < stack_depth_; i++) {
-        stack_[i] = other.stack_[i];
-      }
-    }
-    bool operator==(const X87Stack& other) const {
-      if (stack_depth_ != other.stack_depth_) return false;
-      for (int i = 0; i < stack_depth_; i++) {
-        if (!stack_[i].is(other.stack_[i])) return false;
+    explicit X87Stack(MacroAssembler* masm) : stack_depth_(0), masm_(masm) {
+      for (int i = 0; i < X87Register::kNumAllocatableRegisters; i++) {
+        first_defined_[i] = NULL;
       }
-      return true;
     }
     bool Contains(X87Register reg);
     void Fxch(X87Register reg, int other_slot = 0);
+    void Fxch(X87Register reg, X87Register src);
     void Free(X87Register reg);
     void PrepareToWrite(X87Register reg);
     void CommitWrite(X87Register reg);
     void FlushIfNecessary(LInstruction* instr, LCodeGen* cgen);
+    void RestoreIfNecessary(LInstruction* instr, LCodeGen* cgen);
+    int PhysicalPos(X87Register reg);
     int depth() const { return stack_depth_; }
     void pop() { stack_depth_--; }
+
     void push(X87Register reg) {
       ASSERT(stack_depth_ < X87Register::kNumAllocatableRegisters);
       stack_[stack_depth_] = reg;
       stack_depth_++;
     }
 
+    void leaving(HBasicBlock* block, HBasicBlock* next);
+    void record_usage(X87Register reg, HBasicBlock* block);
+    void record_definition(X87Register reg, HBasicBlock* block);
+
     MacroAssembler* masm() const { return masm_; }
 
    private:
     int ArrayIndex(X87Register reg);
     int st2idx(int pos);
     X87Register stack_[X87Register::kNumAllocatableRegisters];
+    HBasicBlock* first_defined_[X87Register::kNumAllocatableRegisters];
+    HBasicBlock* dominated_[X87Register::kNumAllocatableRegisters];
     int stack_depth_;
     MacroAssembler* const masm_;
   };