[turbofan] Prefer memoized JSGraph constants

For numbers, `JSGraph::Constant(Handle<Object> value)` first checks the
type of `value`, and then calls `JSGraph::Constant` for its type, which
in turn performs some further checks before returning a value.

This patch saves a few `if` checks by making the following changes:

- JSGraph::Constant(0) → JSGraph::ZeroConstant()
- JSGraph::Constant(1) → JSGraph::OneConstant()

Change-Id: I6946c280437b7f1fe80d7c45c6fd9b3571907e07
Reviewed-on: https://chromium-review.googlesource.com/840982Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50288}

src/compiler/js-call-reducer.cc

@@ -906,7 +906,7 @@ Reduction JSCallReducer::ReduceArrayForEach(Handle<JSFunction> function,
       SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
 
   Node* next_k =
-      graph()->NewNode(simplified()->NumberAdd(), k, jsgraph()->Constant(1));
+      graph()->NewNode(simplified()->NumberAdd(), k, jsgraph()->OneConstant());
   checkpoint_params[3] = next_k;
 
   Node* hole_true = nullptr;
@@ -1119,7 +1119,7 @@ Reduction JSCallReducer::ReduceArrayReduce(Handle<JSFunction> function,
       SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
 
   Node* next_k =
-      graph()->NewNode(simplified()->NumberAdd(), k, jsgraph()->Constant(1));
+      graph()->NewNode(simplified()->NumberAdd(), k, jsgraph()->OneConstant());
   checkpoint_params[2] = next_k;
 
   Node* hole_true = nullptr;
@@ -1263,7 +1263,7 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
       receiver, effect, control);
 
   Node* k = graph()->NewNode(simplified()->NumberSubtract(), original_length,
-                             jsgraph()->Constant(1));
+                             jsgraph()->OneConstant());
 
   std::vector<Node*> checkpoint_params({receiver, fncallback, k,
                                         original_length,
@@ -1303,7 +1303,7 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
 
     cur = SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
     k = graph()->NewNode(simplified()->NumberSubtract(), k,
-                         jsgraph()->Constant(1));
+                         jsgraph()->OneConstant());
   }
 
   // Start the loop.
@@ -1323,7 +1323,7 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
   effect = eloop;
 
   Node* continue_test = graph()->NewNode(simplified()->NumberLessThanOrEqual(),
-                                         jsgraph()->Constant(0), k);
+                                         jsgraph()->ZeroConstant(), k);
   Node* continue_branch = graph()->NewNode(common()->Branch(BranchHint::kTrue),
                                            continue_test, control);
 
@@ -1349,7 +1349,7 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
       SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
 
   Node* next_k = graph()->NewNode(simplified()->NumberSubtract(), k,
-                                  jsgraph()->Constant(1));
+                                  jsgraph()->OneConstant());
   checkpoint_params[2] = next_k;
 
   Node* hole_true = nullptr;
@@ -1981,7 +1981,7 @@ Reduction JSCallReducer::ReduceArrayFind(ArrayFindVariant variant,
 
   // Increment k for the next iteration.
   Node* next_k = checkpoint_params[3] =
-      graph()->NewNode(simplified()->NumberAdd(), k, jsgraph()->Constant(1));
+      graph()->NewNode(simplified()->NumberAdd(), k, jsgraph()->OneConstant());
 
   // Replace holes with undefined.
   if (IsHoleyElementsKind(kind)) {

src/compiler/js-create-lowering.cc

@@ -982,9 +982,9 @@ Reduction JSCreateLowering::ReduceJSCreateKeyValueArray(Node* node) {
   AllocationBuilder aa(jsgraph(), effect, graph()->start());
   aa.AllocateArray(2, factory()->fixed_array_map());
   aa.Store(AccessBuilder::ForFixedArrayElement(PACKED_ELEMENTS),
-           jsgraph()->Constant(0), key);
+           jsgraph()->ZeroConstant(), key);
   aa.Store(AccessBuilder::ForFixedArrayElement(PACKED_ELEMENTS),
-           jsgraph()->Constant(1), value);
+           jsgraph()->OneConstant(), value);
   Node* elements = aa.Finish();
 
   AllocationBuilder a(jsgraph(), elements, graph()->start());