[turbofan] Avoid unnecessary (u)int32<->float64 changes in simplified lowering.

src/compiler/simplified-lowering.cc

 // Copyright 2014 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 "src/compiler/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 278 matching lines @@
   void VisitInt64Binop(Node* node) { VisitBinop(node, kMachInt64, kMachInt64); }
   void VisitUint64Binop(Node* node) {
     VisitBinop(node, kMachUint64, kMachUint64);
   }
   void VisitFloat64Cmp(Node* node) { VisitBinop(node, kMachFloat64, kRepBit); }
   void VisitInt32Cmp(Node* node) { VisitBinop(node, kMachInt32, kRepBit); }
   void VisitUint32Cmp(Node* node) { VisitBinop(node, kMachUint32, kRepBit); }
   void VisitInt64Cmp(Node* node) { VisitBinop(node, kMachInt64, kRepBit); }
   void VisitUint64Cmp(Node* node) { VisitBinop(node, kMachUint64, kRepBit); }
 
+  // Infer representation for phi-like nodes.
+  MachineType GetRepresentationForPhi(Node* node, MachineTypeUnion use) {
+    // Phis adapt to the output representation their uses demand.
+    Type* upper = NodeProperties::GetBounds(node).upper;
+    if ((use & kRepMask) == kRepTagged) {
+      // only tagged uses.
+      return kRepTagged;
+    } else if (IsSafeIntAdditiveOperand(node)) {
+      // Integer within [-2^52, 2^52] range.
+      if ((use & kRepMask) == kRepFloat64) {
+        // only float64 uses.
+        return kRepFloat64;
+      } else if (upper->Is(Type::Signed32()) || upper->Is(Type::Unsigned32())) {
+        // multiple uses, but we are within 32 bits range => pick kRepWord32.
+        return kRepWord32;
+      } else if ((use & kRepMask) == kRepWord32 ||
+                 (use & kTypeMask) == kTypeInt32 ||
+                 (use & kTypeMask) == kTypeUint32) {
+        // The type is a safe integer, but we only use 32 bits.
+        return kRepWord32;
+      } else {
+        return kRepFloat64;
+      }
+    } else if (upper->Is(Type::Boolean())) {
+      // multiple uses => pick kRepBit.
+      return kRepBit;
+    } else if (upper->Is(Type::Number())) {
+      // multiple uses => pick kRepFloat64.
+      return kRepFloat64;
+    }
+    return kRepTagged;
+  }
+
   // Helper for handling selects.
-  // TODO(turbofan): Share some code with VisitPhi() below?
   void VisitSelect(Node* node, MachineTypeUnion use,
                    SimplifiedLowering* lowering) {
     ProcessInput(node, 0, kRepBit);
+    MachineType output = GetRepresentationForPhi(node, use);
 
-    // Selects adapt to the output representation their uses demand, pushing
-    // representation changes to their inputs.
     Type* upper = NodeProperties::GetBounds(node).upper;
-    MachineType output = kMachNone;
-    MachineType propagate = kMachNone;
-
-    if (upper->Is(Type::Signed32()) || upper->Is(Type::Unsigned32())) {
-      // legal = kRepTagged | kRepFloat64 | kRepWord32;
-      if ((use & kRepMask) == kRepTagged) {
-        // only tagged uses.
-        output = kRepTagged;
-        propagate = kRepTagged;
-      } else if ((use & kRepMask) == kRepFloat64) {
-        // only float64 uses.
-        output = kRepFloat64;
-        propagate = kRepFloat64;
-      } else {
-        // multiple uses.
-        output = kRepWord32;
-        propagate = kRepWord32;
-      }
-    } else if (upper->Is(Type::Boolean())) {
-      // legal = kRepTagged | kRepBit;
-      if ((use & kRepMask) == kRepTagged) {
-        // only tagged uses.
-        output = kRepTagged;
-        propagate = kRepTagged;
-      } else {
-        // multiple uses.
-        output = kRepBit;
-        propagate = kRepBit;
-      }
-    } else if (upper->Is(Type::Number())) {
-      // legal = kRepTagged | kRepFloat64;
-      if ((use & kRepMask) == kRepTagged) {
-        // only tagged uses.
-        output = kRepTagged;
-        propagate = kRepTagged;
-      } else {
-        // multiple uses.
-        output = kRepFloat64;
-        propagate = kRepFloat64;
-      }
-    } else {
-      // legal = kRepTagged;
-      output = kRepTagged;
-      propagate = kRepTagged;
-    }
-
     MachineType output_type =
         static_cast<MachineType>(changer_->TypeFromUpperBound(upper) | output);
     SetOutput(node, output_type);
 
     if (lower()) {
       // Update the select operator.
       SelectParameters p = SelectParametersOf(node->op());
       MachineType type = static_cast<MachineType>(output_type);
       if (type != p.type()) {
         node->set_op(lowering->common()->Select(type, p.hint()));
       }
 
       // Convert inputs to the output representation of this select.
       ProcessInput(node, 1, output_type);
       ProcessInput(node, 2, output_type);
     } else {
       // Propagate {use} of the select to value inputs.
       MachineType use_type =
-          static_cast<MachineType>((use & kTypeMask) | propagate);
+          static_cast<MachineType>((use & kTypeMask) | output);
       ProcessInput(node, 1, use_type);
       ProcessInput(node, 2, use_type);
     }
   }
 
   // Helper for handling phis.
   void VisitPhi(Node* node, MachineTypeUnion use,
                 SimplifiedLowering* lowering) {
-    // Phis adapt to the output representation their uses demand, pushing
-    // representation changes to their inputs.
+    MachineType output = GetRepresentationForPhi(node, use);
+
     Type* upper = NodeProperties::GetBounds(node).upper;
-    MachineType output = kMachNone;
-    MachineType propagate = kMachNone;
-
-    if (upper->Is(Type::Signed32()) || upper->Is(Type::Unsigned32())) {
-      // legal = kRepTagged | kRepFloat64 | kRepWord32;
-      if ((use & kRepMask) == kRepTagged) {
-        // only tagged uses.
-        output = kRepTagged;
-        propagate = kRepTagged;
-      } else if ((use & kRepMask) == kRepFloat64) {
-        // only float64 uses.
-        output = kRepFloat64;
-        propagate = kRepFloat64;
-      } else {
-        // multiple uses.
-        output = kRepWord32;
-        propagate = kRepWord32;
-      }
-    } else if (upper->Is(Type::Boolean())) {
-      // legal = kRepTagged | kRepBit;
-      if ((use & kRepMask) == kRepTagged) {
-        // only tagged uses.
-        output = kRepTagged;
-        propagate = kRepTagged;
-      } else {
-        // multiple uses.
-        output = kRepBit;
-        propagate = kRepBit;
-      }
-    } else if (upper->Is(Type::Number())) {
-      // legal = kRepTagged | kRepFloat64;
-      if ((use & kRepMask) == kRepTagged) {
-        // only tagged uses.
-        output = kRepTagged;
-        propagate = kRepTagged;
-      } else {
-        // multiple uses.
-        output = kRepFloat64;
-        propagate = kRepFloat64;
-      }
-    } else {
-      // legal = kRepTagged;
-      output = kRepTagged;
-      propagate = kRepTagged;
-    }
-
     MachineType output_type =
         static_cast<MachineType>(changer_->TypeFromUpperBound(upper) | output);
     SetOutput(node, output_type);
 
     int values = node->op()->ValueInputCount();
 
     if (lower()) {
       // Update the phi operator.
       MachineType type = static_cast<MachineType>(output_type);
       if (type != OpParameter<MachineType>(node)) {
         node->set_op(lowering->common()->Phi(type, values));
       }
 
       // Convert inputs to the output representation of this phi.
       Node::Inputs inputs = node->inputs();
       for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end();
            ++iter, --values) {
         // TODO(titzer): it'd be nice to have distinguished edge kinds here.
         ProcessInput(node, iter.index(), values > 0 ? output_type : 0);
       }
     } else {
       // Propagate {use} of the phi to value inputs, and 0 to control.
       Node::Inputs inputs = node->inputs();
       MachineType use_type =
-          static_cast<MachineType>((use & kTypeMask) | propagate);
+          static_cast<MachineType>((use & kTypeMask) | output);
       for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end();
            ++iter, --values) {
         // TODO(titzer): it'd be nice to have distinguished edge kinds here.
         ProcessInput(node, iter.index(), values > 0 ? use_type : 0);
       }
     }
   }
 
   const Operator* Int32Op(Node* node) {
     return changer_->Int32OperatorFor(node->opcode());
@@ skipping 253 matching lines @@
           break;
         }
         // => Float64Mod
         VisitFloat64Binop(node);
         if (lower()) node->set_op(Float64Op(node));
         break;
       }
       case IrOpcode::kNumberToInt32: {
         MachineTypeUnion use_rep = use & kRepMask;
         Node* input = node->InputAt(0);
+        Type* in_upper = NodeProperties::GetBounds(input).upper;
         MachineTypeUnion in = GetInfo(input)->output;
-        if (NodeProperties::GetBounds(input).upper->Is(Type::Signed32())) {
+        if (in_upper->Is(Type::Signed32())) {
           // If the input has type int32, pass through representation.
           VisitUnop(node, kTypeInt32 | use_rep, kTypeInt32 | use_rep);
           if (lower()) DeferReplacement(node, node->InputAt(0));
         } else if ((in & kTypeMask) == kTypeUint32 ||
                    (in & kTypeMask) == kTypeInt32 ||
+                   in_upper->Is(Type::Unsigned32()) ||
                    (in & kRepMask) == kRepWord32) {
           // Just change representation if necessary.
           VisitUnop(node, kTypeInt32 | kRepWord32, kTypeInt32 | kRepWord32);
           if (lower()) DeferReplacement(node, node->InputAt(0));
         } else {
           // Require the input in float64 format and perform truncation.
           // TODO(turbofan): avoid a truncation with a smi check.
           VisitUnop(node, kTypeInt32 | kRepFloat64, kTypeInt32 | kRepWord32);
           if (lower())
             node->set_op(lowering->machine()->TruncateFloat64ToInt32());
         }
         break;
       }
       case IrOpcode::kNumberToUint32: {
         MachineTypeUnion use_rep = use & kRepMask;
         Node* input = node->InputAt(0);
+        Type* in_upper = NodeProperties::GetBounds(input).upper;
         MachineTypeUnion in = GetInfo(input)->output;
-        if (NodeProperties::GetBounds(input).upper->Is(Type::Unsigned32())) {
+        if (in_upper->Is(Type::Unsigned32())) {
           // If the input has type uint32, pass through representation.
           VisitUnop(node, kTypeUint32 | use_rep, kTypeUint32 | use_rep);
           if (lower()) DeferReplacement(node, node->InputAt(0));
         } else if ((in & kTypeMask) == kTypeUint32 ||
                    (in & kTypeMask) == kTypeInt32 ||
+                   in_upper->Is(Type::Signed32()) ||
                    (in & kRepMask) == kRepWord32) {
           // Just change representation if necessary.
           VisitUnop(node, kTypeUint32 | kRepWord32, kTypeUint32 | kRepWord32);
           if (lower()) DeferReplacement(node, node->InputAt(0));
         } else {
           // Require the input in float64 format and perform truncation.
           // TODO(turbofan): avoid a truncation with a smi check.
           VisitUnop(node, kTypeUint32 | kRepFloat64, kTypeUint32 | kRepWord32);
           if (lower())
             node->set_op(lowering->machine()->TruncateFloat64ToInt32());
@@ skipping 756 matching lines @@
 
 void SimplifiedLowering::DoStringLessThanOrEqual(Node* node) {
   node->set_op(machine()->IntLessThanOrEqual());
   node->ReplaceInput(0, StringComparison(node, true));
   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8