Let NaN flow as double into HBranch

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index ef860e0d8774771c00378fc6b7bc8129726d49d6..2f3c522d2b1fe51a0638316a4386f969bef05c43 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -2198,7 +2198,7 @@ void LCodeGen::DoBranch(LBranch* instr) {
     DwVfpRegister reg = ToDoubleRegister(instr->value());
     // Test the double value. Zero and NaN are false.
     __ VFPCompareAndSetFlags(reg, 0.0);
-    __ cmp(r0, r0, vs);  // If NaN, set the Z flag.
+    __ cmp(r0, r0, vs);  // If NaN, set the Z flag. (NaN -> false)
     EmitBranch(true_block, false_block, ne);
   } else {
     ASSERT(r.IsTagged());
@@ -2212,6 +2212,19 @@ void LCodeGen::DoBranch(LBranch* instr) {
       ASSERT(!info()->IsStub());
       __ cmp(reg, Operand::Zero());
       EmitBranch(true_block, false_block, ne);
+    } else if (type.IsJSArray()) {
+      EmitBranch(true_block, false_block, al);
+    } else if (type.IsHeapNumber()) {
+      DwVfpRegister dbl_scratch = double_scratch0();
+      __ vldr(dbl_scratch, FieldMemOperand(reg, HeapNumber::kValueOffset));
+      // Test the double value. Zero and NaN are false.
+      __ VFPCompareAndSetFlags(dbl_scratch, 0.0);
+      __ cmp(r0, r0, vs);  // If NaN, set the Z flag. (NaN)
+      EmitBranch(true_block, false_block, ne);
+    } else if (type.IsString()) {
+      __ ldr(ip, FieldMemOperand(reg, String::kLengthOffset));
+      __ cmp(ip, Operand::Zero());
+      EmitBranch(true_block, false_block, ne);
     } else {
       Label* true_label = chunk_->GetAssemblyLabel(true_block);
       Label* false_label = chunk_->GetAssemblyLabel(false_block);
@@ -2299,8 +2312,10 @@ void LCodeGen::DoBranch(LBranch* instr) {
         __ bind(&not_heap_number);
       }
 
-      // We've seen something for the first time -> deopt.
-      DeoptimizeIf(al, instr->environment());
+      if (expected != ToBooleanStub::all_types()) {
+        // We've seen something for the first time -> deopt.
+        DeoptimizeIf(al, instr->environment());
+      }
     }
   }
 }