Use signaling NaN for holes in fixed double arrays.

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 1699 matching lines @@
   }
 }
 
 
 void LCodeGen::DoConstantS(LConstantS* instr) {
   __ Move(ToRegister(instr->result()), instr->value());
 }
 
 
 void LCodeGen::DoConstantD(LConstantD* instr) {
-  DCHECK(instr->result()->IsDoubleRegister());
-  XMMRegister res = ToDoubleRegister(instr->result());
-  double v = instr->value();
-  uint64_t int_val = bit_cast<uint64_t, double>(v);
-  // Use xor to produce +0.0 in a fast and compact way, but avoid to
-  // do so if the constant is -0.0.
-  if (int_val == 0) {
-    __ xorps(res, res);
-  } else {
-    Register tmp = ToRegister(instr->temp());
-    __ Set(tmp, int_val);
-    __ movq(res, tmp);
-  }
+  __ Move(ToDoubleRegister(instr->result()), instr->bits());
 }
 
 
 void LCodeGen::DoConstantE(LConstantE* instr) {
   __ LoadAddress(ToRegister(instr->result()), instr->value());
 }
 
 
 void LCodeGen::DoConstantT(LConstantT* instr) {
   Handle<Object> object = instr->value(isolate());
@@ skipping 2235 matching lines @@
 
 void LCodeGen::DoMathLog(LMathLog* instr) {
   DCHECK(instr->value()->Equals(instr->result()));
   XMMRegister input_reg = ToDoubleRegister(instr->value());
   XMMRegister xmm_scratch = double_scratch0();
   Label positive, done, zero;
   __ xorps(xmm_scratch, xmm_scratch);
   __ ucomisd(input_reg, xmm_scratch);
   __ j(above, &positive, Label::kNear);
   __ j(not_carry, &zero, Label::kNear);
-  ExternalReference nan =
-      ExternalReference::address_of_canonical_non_hole_nan();
-  Operand nan_operand = masm()->ExternalOperand(nan);
-  __ movsd(input_reg, nan_operand);
+  __ pcmpeqd(input_reg, input_reg);
   __ jmp(&done, Label::kNear);
   __ bind(&zero);
   ExternalReference ninf =
       ExternalReference::address_of_negative_infinity();
   Operand ninf_operand = masm()->ExternalOperand(ninf);
   __ movsd(input_reg, ninf_operand);
   __ jmp(&done, Label::kNear);
   __ bind(&positive);
   __ fldln2();
   __ subp(rsp, Immediate(kDoubleSize));
@@ skipping 403 matching lines @@
 void LCodeGen::DoStoreKeyedFixedDoubleArray(LStoreKeyed* instr) {
   XMMRegister value = ToDoubleRegister(instr->value());
   LOperand* key = instr->key();
   if (kPointerSize == kInt32Size && !key->IsConstantOperand() &&
       instr->hydrogen()->IsDehoisted()) {
     // Sign extend key because it could be a 32 bit negative value
     // and the dehoisted address computation happens in 64 bits
     __ movsxlq(ToRegister(key), ToRegister(key));
   }
   if (instr->NeedsCanonicalization()) {
-    Label have_value;
-
-    __ ucomisd(value, value);
-    __ j(parity_odd, &have_value, Label::kNear);  // NaN.
-
-    __ Set(kScratchRegister,
-           bit_cast<uint64_t>(
-               FixedDoubleArray::canonical_not_the_hole_nan_as_double()));
-    __ movq(value, kScratchRegister);
-
-    __ bind(&have_value);
+    XMMRegister xmm_scratch = double_scratch0();
+    // Turn potential sNaN value into qNaN.
+    __ xorps(xmm_scratch, xmm_scratch);
+    __ subsd(value, xmm_scratch);
   }
 
   Operand double_store_operand = BuildFastArrayOperand(
       instr->elements(),
       key,
       instr->hydrogen()->key()->representation(),
       FAST_DOUBLE_ELEMENTS,
       instr->base_offset());
 
   __ movsd(double_store_operand, value);
@@ skipping 517 matching lines @@
     }
     __ jmp(&done, Label::kNear);
 
     if (can_convert_undefined_to_nan) {
       __ bind(&convert);
 
       // Convert undefined (and hole) to NaN. Compute NaN as 0/0.
       __ CompareRoot(input_reg, Heap::kUndefinedValueRootIndex);
       DeoptimizeIf(not_equal, instr, "not a heap number/undefined");
 
-      __ xorps(result_reg, result_reg);
-      __ divsd(result_reg, result_reg);
+      __ pcmpeqd(result_reg, result_reg);
       __ jmp(&done, Label::kNear);
     }
   } else {
     DCHECK(mode == NUMBER_CANDIDATE_IS_SMI);
   }
 
   // Smi to XMM conversion
   __ bind(&load_smi);
   __ SmiToInteger32(kScratchRegister, input_reg);
   __ Cvtlsi2sd(result_reg, kScratchRegister);
@@ skipping 956 matching lines @@
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64