MIPS: Reland and fix "Fix LoadFieldByIndex to take mutable heap-numbers into account."

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index e6f52d84b707ef82d3385eddea892525039b744d..a60829d5e8e726e0706a726969e0697a0f62818d 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -5792,13 +5792,61 @@ void LCodeGen::DoCheckMapValue(LCheckMapValue* instr) {
 }
 
 
+void LCodeGen::DoDeferredLoadMutableDouble(LLoadFieldByIndex* instr,
+                                           Register result,
+                                           Register object,
+                                           Register index) {
+  PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
+  __ Push(object);
+  __ Push(index);

[Paul Lind, 2014/03/31 22:39:59]

You should combine the two Pushes, to save an instruction.

+  __ mov(cp, zero_reg);
+  __ CallRuntimeSaveDoubles(Runtime::kLoadMutableDouble);
+  RecordSafepointWithRegisters(
+     instr->pointer_map(), 2, Safepoint::kNoLazyDeopt);
+  __ StoreToSafepointRegisterSlot(v0, result);
+}
+
+
 void LCodeGen::DoLoadFieldByIndex(LLoadFieldByIndex* instr) {
+  class DeferredLoadMutableDouble V8_FINAL : public LDeferredCode {
+   public:
+    DeferredLoadMutableDouble(LCodeGen* codegen,
+                              LLoadFieldByIndex* instr,
+                              Register result,
+                              Register object,
+                              Register index)
+        : LDeferredCode(codegen),
+          instr_(instr),
+          result_(result),
+          object_(object),
+          index_(index) {
+    }
+    virtual void Generate() V8_OVERRIDE {
+      codegen()->DoDeferredLoadMutableDouble(instr_, result_, object_, index_);
+    }
+    virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
+   private:
+    LLoadFieldByIndex* instr_;
+    Register result_;
+    Register object_;
+    Register index_;
+  };
+
   Register object = ToRegister(instr->object());
   Register index = ToRegister(instr->index());
   Register result = ToRegister(instr->result());
   Register scratch = scratch0();
 
+  DeferredLoadMutableDouble* deferred;
+  deferred = new(zone()) DeferredLoadMutableDouble(
+      this, instr, result, object, index);
+
   Label out_of_object, done;
+
+  __ And(scratch, index, Operand(Smi::FromInt(1)));
+  __ Branch(deferred->entry(), ne, scratch, Operand(zero_reg));
+  __ sra(index, index, 1);
+
   __ Branch(USE_DELAY_SLOT, &out_of_object, lt, index, Operand(zero_reg));
   __ sll(scratch, index, kPointerSizeLog2 - kSmiTagSize);  // In delay slot.
 
@@ -5814,6 +5862,7 @@ void LCodeGen::DoLoadFieldByIndex(LLoadFieldByIndex* instr) {
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
+  __ bind(deferred->exit());
   __ bind(&done);
 }