[turbofan] The PlainPrimitiveToNumber operator cannot have side effects.

An invocation of the ToNumber builtin resulting from lowering the
PlainPrimitiveToNumber cannot have any observable side effects and
thus the builtin call itself is eliminatable.

R=yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2239923004
Cr-Commit-Position: refs/heads/master@{#38593}

src/compiler/effect-control-linearizer.cc

@@ -2524,7 +2524,7 @@ EffectControlLinearizer::LowerPlainPrimitiveToNumber(Node* node, Node* effect,
   Node* value = node->InputAt(0);
   Node* result = effect =
       graph()->NewNode(ToNumberOperator(), jsgraph()->ToNumberBuiltinConstant(),
-                       value, jsgraph()->NoContextConstant(), effect, control);
+                       value, jsgraph()->NoContextConstant(), effect);
   return ValueEffectControl(result, effect, control);
 }
 
@@ -2547,7 +2547,7 @@ EffectControlLinearizer::LowerPlainPrimitiveToWord32(Node* node, Node* effect,
   {
     vfalse0 = efalse0 = graph()->NewNode(
         ToNumberOperator(), jsgraph()->ToNumberBuiltinConstant(), value,
-        jsgraph()->NoContextConstant(), efalse0, if_false0);
+        jsgraph()->NoContextConstant(), efalse0);
 
     Node* check1 = ObjectIsSmi(vfalse0);
     Node* branch1 = graph()->NewNode(common()->Branch(), check1, if_false0);
@@ -2603,7 +2603,7 @@ EffectControlLinearizer::LowerPlainPrimitiveToFloat64(Node* node, Node* effect,
   {
     vfalse0 = efalse0 = graph()->NewNode(
         ToNumberOperator(), jsgraph()->ToNumberBuiltinConstant(), value,
-        jsgraph()->NoContextConstant(), efalse0, if_false0);
+        jsgraph()->NoContextConstant(), efalse0);
 
     Node* check1 = ObjectIsSmi(vfalse0);
     Node* branch1 = graph()->NewNode(common()->Branch(), check1, if_false0);
@@ -3307,7 +3307,7 @@ Operator const* EffectControlLinearizer::ToNumberOperator() {
     CallDescriptor::Flags flags = CallDescriptor::kNoFlags;
     CallDescriptor* desc = Linkage::GetStubCallDescriptor(
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
-        Operator::kNoThrow);
+        Operator::kEliminatable);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();