ARM64: Generate optimized code for Math.floor and Math.round with double outputs.

src/hydrogen-instructions.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "v8.h"
 
 #include "double.h"
 #include "factory.h"
 #include "hydrogen-infer-representation.h"
 #include "property-details-inl.h"
@@ skipping 3680 matching lines @@
 }
 
 
 HType HChange::CalculateInferredType() {
   if (from().IsDouble() && to().IsTagged()) return HType::HeapNumber();
   return type();
 }
 
 
 Representation HUnaryMathOperation::RepresentationFromInputs() {
+  if (SupportsFlexibleFloorAndRound() &&
+      (op_ == kMathFloor || op_ == kMathRound)) {
+    // Floor and Round always take a double input. The integral result can be
+    // used as an integer or a double. Infer the representation from the uses.
+    return Representation::None();
+  }
   Representation rep = representation();
   // If any of the actual input representation is more general than what we
   // have so far but not Tagged, use that representation instead.
   Representation input_rep = value()->representation();
   if (!input_rep.IsTagged()) {
     rep = rep.generalize(input_rep);
   }
   return rep;
 }
 
@@ skipping 448 matching lines @@
       }
       default:
         UNREACHABLE();
         break;
     }
   } while (false);
   return new(zone) HUnaryMathOperation(context, value, op);
 }
 
 
+Representation HUnaryMathOperation::RepresentationFromUses() {
+  if (op_ != kMathFloor && op_ != kMathRound) {
+    return HValue::RepresentationFromUses();
+  }
+
+  // The instruction can have an int32 or double output. Prefer a double
+  // representation if there are double uses.
+  bool use_double = false;
+
+  for (HUseIterator it(uses()); !it.Done(); it.Advance()) {
+    HValue* use = it.value();
+    int use_index = it.index();
+    Representation rep_observed = use->observed_input_representation(use_index);
+    Representation rep_required = use->RequiredInputRepresentation(use_index);
+    use_double |= (rep_observed.IsDouble() || rep_required.IsDouble());
+    if (use_double && !FLAG_trace_representation) {
+      // Having seen one double is enough.
+      break;
+    }
+    if (FLAG_trace_representation) {
+      if (!rep_required.IsDouble() || rep_observed.IsDouble()) {
+        PrintF("#%d %s is used by #%d %s as %s%s\n",
+               id(), Mnemonic(), use->id(),
+               use->Mnemonic(), rep_observed.Mnemonic(),
+               (use->CheckFlag(kTruncatingToInt32) ? "-trunc" : ""));
+      } else {
+        PrintF("#%d %s is required by #%d %s as %s%s\n",
+               id(), Mnemonic(), use->id(),
+               use->Mnemonic(), rep_required.Mnemonic(),
+               (use->CheckFlag(kTruncatingToInt32) ? "-trunc" : ""));
+      }
+    }
+  }
+  return use_double ? Representation::Double() : Representation::Integer32();
+}
+
+
 HInstruction* HPower::New(Zone* zone,
                           HValue* context,
                           HValue* left,
                           HValue* right) {
   if (FLAG_fold_constants && left->IsConstant() && right->IsConstant()) {
     HConstant* c_left = HConstant::cast(left);
     HConstant* c_right = HConstant::cast(right);
     if (c_left->HasNumberValue() && c_right->HasNumberValue()) {
       double result = power_helper(c_left->DoubleValue(),
                                    c_right->DoubleValue());
@@ skipping 542 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal