[turbofan] Generate Float constants for certain checked conversions

This change ensures that we do not try to check the conversion of a floating
point constant, but insert the floating point constant instead.

Change-Id: I1c65e3a69acaea2ff805ba10317f64c0ac0ba098
Reviewed-on: https://chromium-review.googlesource.com/c/1340257Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57630}

src/compiler/representation-change.cc

@@ -605,18 +605,17 @@ Node* RepresentationChanger::GetFloat32RepresentationFor(
 Node* RepresentationChanger::GetFloat64RepresentationFor(
     Node* node, MachineRepresentation output_rep, Type output_type,
     Node* use_node, UseInfo use_info) {
-  // Eagerly fold representation changes for constants.
-  if ((use_info.type_check() == TypeCheckKind::kNone)) {
-    // TODO(jarin) Handle checked constant conversions.
-    switch (node->opcode()) {
-      case IrOpcode::kNumberConstant:
-        return jsgraph()->Float64Constant(OpParameter<double>(node->op()));
-      case IrOpcode::kInt32Constant:
-      case IrOpcode::kFloat64Constant:
-      case IrOpcode::kFloat32Constant:
-        UNREACHABLE();
-        break;
-      default:
+  NumberMatcher m(node);
+  if (m.HasValue()) {
+    switch (use_info.type_check()) {
+      case TypeCheckKind::kNone:
+      case TypeCheckKind::kNumber:
+      case TypeCheckKind::kNumberOrOddball:
+        return jsgraph()->Float64Constant(m.Value());
+      case TypeCheckKind::kHeapObject:
+      case TypeCheckKind::kSigned32:
+      case TypeCheckKind::kSigned64:
+      case TypeCheckKind::kSignedSmall:
         break;
     }
   }

test/cctest/compiler/test-representation-change.cc

@@ -204,6 +204,15 @@ TEST(ToFloat64_constant) {
         UseInfo(MachineRepresentation::kFloat64, Truncation::None()));
     r.CheckFloat64Constant(c, i);
   }
+
+  {
+    Node* n = r.jsgraph()->Constant(0);
+    Node* use = r.Return(n);
+    Node* c = r.changer()->GetRepresentationFor(
+        n, MachineRepresentation::kWord64, Type::Range(0, 0, r.zone()), use,
+        UseInfo(MachineRepresentation::kFloat64, Truncation::None()));
+    r.CheckFloat64Constant(c, 0);
+  }
 }