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

src/compiler/js-builtin-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/diamond.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/js-builtin-reducer.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
 #include "src/types.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
@@ skipping 84 matching lines @@
 Reduction JSBuiltinReducer::ReduceMathAbs(Node* node) {
   JSCallReduction r(node);
   if (r.InputsMatchOne(Type::Unsigned32())) {
     // Math.abs(a:uint32) -> a
     return Replace(r.left());
   }
   if (r.InputsMatchOne(Type::Number())) {
     // Math.abs(a:number) -> (a > 0 ? a : 0 - a)
     Node* value = r.left();
     Node* zero = jsgraph()->ZeroConstant();
-    Node* control = graph()->start();
-    Node* tag = graph()->NewNode(simplified()->NumberLessThan(), zero, value);
-
-    Node* branch = graph()->NewNode(common()->Branch(), tag, control);
-    Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
-    Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
-    Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
-
+    Node* cmp = graph()->NewNode(simplified()->NumberLessThan(), zero, value);
+    Diamond d(graph(), common(), cmp);
     Node* neg = graph()->NewNode(simplified()->NumberSubtract(), zero, value);
-    value = graph()->NewNode(common()->Phi(kMachNone, 2), value, neg, merge);
-    return Replace(value);
+    return Replace(d.Phi(kMachNone, value, neg));
   }
   return NoChange();
 }
 
 
 // ECMA-262, section 15.8.2.17.
 Reduction JSBuiltinReducer::ReduceMathSqrt(Node* node) {
   JSCallReduction r(node);
   if (r.InputsMatchOne(Type::Number())) {
     // Math.sqrt(a:number) -> Float64Sqrt(a)
@@ skipping 13 matching lines @@
   }
   if (r.InputsMatchOne(Type::Number())) {
     // Math.max(a:number) -> a
     return Replace(r.left());
   }
   if (r.InputsMatchAll(Type::Integral32())) {
     // Math.max(a:int32, b:int32, ...)
     Node* value = r.GetJSCallInput(0);
     for (int i = 1; i < r.GetJSCallArity(); i++) {
       Node* p = r.GetJSCallInput(i);
-      Node* control = graph()->start();
-      Node* tag = graph()->NewNode(simplified()->NumberLessThan(), value, p);
-
-      Node* branch = graph()->NewNode(common()->Branch(), tag, control);
-      Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
-      Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
-      Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
-
-      value = graph()->NewNode(common()->Phi(kMachNone, 2), p, value, merge);
+      Node* cmp = graph()->NewNode(simplified()->NumberLessThan(), value, p);
+      Diamond d(graph(), common(), cmp);
+      value = d.Phi(kMachNone, p, value);
     }
     return Replace(value);
   }
   return NoChange();
 }
 
 
 // ES6 draft 08-24-14, section 20.2.2.19.
 Reduction JSBuiltinReducer::ReduceMathImul(Node* node) {
   JSCallReduction r(node);
@@ skipping 67 matching lines @@
       return ReplaceWithPureReduction(node, ReduceMathCeil(node));
     default:
       break;
   }
   return NoChange();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8