Introduce Diamond, a helper for building diamond-shaped control patterns.

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"
 #include "src/compiler/generic-node-inl.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-matchers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 MachineOperatorReducer::MachineOperatorReducer(JSGraph* jsgraph)
@@ skipping 613 matching lines @@
   }
   if (m.right().HasValue()) {
     Node* const dividend = m.left().node();
     int32_t const divisor = Abs(m.right().Value());
     if (base::bits::IsPowerOfTwo32(divisor)) {
       uint32_t const mask = divisor - 1;
       Node* const zero = Int32Constant(0);
 
       Node* check =
           graph()->NewNode(machine()->Int32LessThan(), dividend, zero);
-      Node* branch = graph()->NewNode(common()->Branch(BranchHint::kFalse),
-                                      check, graph()->start());
-
-      Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+      Diamond d(graph(), common(), check, BranchHint::kFalse);
       Node* neg = Int32Sub(zero, Word32And(Int32Sub(zero, dividend), mask));
-
-      Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
       Node* pos = Word32And(dividend, mask);
-
-      Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
-
-      DCHECK_EQ(3, node->InputCount());
-      node->set_op(common()->Phi(kMachInt32, 2));
-      node->ReplaceInput(0, neg);
-      node->ReplaceInput(1, pos);
-      node->ReplaceInput(2, merge);
+      d.OverwriteWithPhi(node, kMachInt32, neg, pos);
     } else {
       Node* quotient = Int32Div(dividend, divisor);
       node->set_op(machine()->Int32Sub());
       DCHECK_EQ(dividend, node->InputAt(0));
       node->ReplaceInput(1, Int32Mul(quotient, Int32Constant(divisor)));
       node->TrimInputCount(2);
     }
     return Changed(node);
   }
   return NoChange();
@@ skipping 109 matching lines @@
 MachineOperatorBuilder* MachineOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 
 Graph* MachineOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8