[turbofan] Push TruncateFloat64ToInt32 into phis.

src/compiler/machine-operator-reducer.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/machine-operator-reducer.h"
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/codegen.h"
 #include "src/compiler/diamond.h"
@@ skipping 505 matching lines @@
     case IrOpcode::kChangeUint32ToFloat64: {
       Uint32Matcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceFloat64(FastUI2D(m.Value()));
       break;
     }
     case IrOpcode::kChangeUint32ToUint64: {
       Uint32Matcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceInt64(static_cast<uint64_t>(m.Value()));
       break;
     }
-    case IrOpcode::kTruncateFloat64ToInt32: {
-      Float64Matcher m(node->InputAt(0));
-      if (m.HasValue()) return ReplaceInt32(DoubleToInt32(m.Value()));
-      if (m.IsChangeInt32ToFloat64()) return Replace(m.node()->InputAt(0));
-      break;
-    }
+    case IrOpcode::kTruncateFloat64ToInt32:
+      return ReduceTruncateFloat64ToInt32(node);
     case IrOpcode::kTruncateInt64ToInt32: {
       Int64Matcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceInt32(static_cast<int32_t>(m.Value()));
       if (m.IsChangeInt32ToInt64()) return Replace(m.node()->InputAt(0));
       break;
     }
     case IrOpcode::kTruncateFloat64ToFloat32: {
       Float64Matcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceFloat32(DoubleToFloat32(m.Value()));
       if (m.IsChangeFloat32ToFloat64()) return Replace(m.node()->InputAt(0));
@@ skipping 143 matching lines @@
       DCHECK_EQ(dividend, node->InputAt(0));
       node->ReplaceInput(1, Int32Mul(quotient, Uint32Constant(divisor)));
     }
     node->TrimInputCount(2);
     return Changed(node);
   }
   return NoChange();
 }
 
 
+Reduction MachineOperatorReducer::ReduceTruncateFloat64ToInt32(Node* node) {
+  Float64Matcher m(node->InputAt(0));
+  if (m.HasValue()) return ReplaceInt32(DoubleToInt32(m.Value()));
+  if (m.IsChangeInt32ToFloat64()) return Replace(m.node()->InputAt(0));
+  if (m.IsPhi()) {
+    Node* const phi = m.node();
+    DCHECK_EQ(kRepFloat64, RepresentationOf(OpParameter<MachineType>(phi)));
+    if (phi->OwnedBy(node)) {
+      // TruncateFloat64ToInt32(Phi[Float64](x1,...,xn))
+      //   => Phi[Int32](TruncateFloat64ToInt32(x1),
+      //                 ...,
+      //                 TruncateFloat64ToInt32(xn))
+      const int value_input_count = phi->InputCount() - 1;
+      for (int i = 0; i < value_input_count; ++i) {
+        Node* input = graph()->NewNode(machine()->TruncateFloat64ToInt32(),
+                                       phi->InputAt(i));
+        // TODO(bmeurer): Reschedule input for reduction once we have Revisit()
+        // instead of recursing into ReduceTruncateFloat64ToInt32() here.
+        Reduction reduction = ReduceTruncateFloat64ToInt32(input);
+        if (reduction.Changed()) input = reduction.replacement();
+        phi->ReplaceInput(i, input);
+      }
+      phi->set_op(common()->Phi(kMachInt32, value_input_count));
+      return Replace(phi);
+    }
+  }
+  return NoChange();
+}
+
+
 Reduction MachineOperatorReducer::ReduceStore(Node* node) {
   MachineType const rep =
       RepresentationOf(StoreRepresentationOf(node->op()).machine_type());
   Node* const value = node->InputAt(2);
   switch (value->opcode()) {
     case IrOpcode::kWord32And: {
       Uint32BinopMatcher m(value);
       if (m.right().HasValue() &&
           ((rep == kRepWord8 && (m.right().Value() & 0xff) == 0xff) ||
            (rep == kRepWord16 && (m.right().Value() & 0xffff) == 0xffff))) {
@@ skipping 67 matching lines @@
 MachineOperatorBuilder* MachineOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 
 Graph* MachineOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8