Let NaN flow as double into HBranch

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1901 matching lines @@
     Register reg = ToRegister(instr->value());
     HType type = instr->hydrogen()->value()->type();
     if (type.IsBoolean()) {
       ASSERT(!info()->IsStub());
       __ CompareRoot(reg, Heap::kTrueValueRootIndex);
       EmitBranch(instr, equal);
     } else if (type.IsSmi()) {
       ASSERT(!info()->IsStub());
       __ SmiCompare(reg, Smi::FromInt(0));
       EmitBranch(instr, not_equal);
+    } else if (type.IsJSArray()) {
+      ASSERT(!info()->IsStub());
+      EmitBranch(instr, no_condition);
+    } else if (type.IsHeapNumber()) {
+      ASSERT(!info()->IsStub());
+      __ xorps(xmm0, xmm0);
+      __ ucomisd(xmm0, FieldOperand(reg, HeapNumber::kValueOffset));
+      EmitBranch(instr, not_equal);
+    } else if (type.IsString()) {
+      ASSERT(!info()->IsStub());
+      __ cmpq(FieldOperand(reg, String::kLengthOffset), Immediate(0));
+      EmitBranch(instr, not_equal);
     } else {
       ToBooleanStub::Types expected = instr->hydrogen()->expected_input_types();
       // Avoid deopts in the case where we've never executed this path before.
-      if (expected.IsEmpty()) expected = ToBooleanStub::all_types();
+      if (expected.IsEmpty()) expected = ToBooleanStub::Types::Generic();
 
       if (expected.Contains(ToBooleanStub::UNDEFINED)) {
         // undefined -> false.
         __ CompareRoot(reg, Heap::kUndefinedValueRootIndex);
         __ j(equal, instr->FalseLabel(chunk_));
       }
       if (expected.Contains(ToBooleanStub::BOOLEAN)) {
         // true -> true.
         __ CompareRoot(reg, Heap::kTrueValueRootIndex);
         __ j(equal, instr->TrueLabel(chunk_));
@@ skipping 52 matching lines @@
         Label not_heap_number;
         __ CompareRoot(map, Heap::kHeapNumberMapRootIndex);
         __ j(not_equal, &not_heap_number, Label::kNear);
         __ xorps(xmm0, xmm0);
         __ ucomisd(xmm0, FieldOperand(reg, HeapNumber::kValueOffset));
         __ j(zero, instr->FalseLabel(chunk_));
         __ jmp(instr->TrueLabel(chunk_));
         __ bind(&not_heap_number);
       }
 
-      // We've seen something for the first time -> deopt.
-      DeoptimizeIf(no_condition, instr->environment());
+      if (!expected.IsGeneric()) {
+        // We've seen something for the first time -> deopt.
+        // This can only happen if we are not generic already.
+        DeoptimizeIf(no_condition, instr->environment());
+      }
     }
   }
 }
 
 
 void LCodeGen::EmitGoto(int block) {
   if (!IsNextEmittedBlock(block)) {
     __ jmp(chunk_->GetAssemblyLabel(chunk_->LookupDestination(block)));
   }
 }
@@ skipping 3636 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64