[turbofan] Introduce new operators Float32SubPreserveNan and Float64SubPreserveNan for wasm.

src/compiler/arm/instruction-selector-arm.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/base/adapters.h"
 #include "src/base/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 1187 matching lines @@
   if (m.right().IsFloat64Mul() && CanCover(node, m.right().node())) {
     Float64BinopMatcher mright(m.right().node());
     Emit(kArmVmlaF64, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
          g.UseRegister(mright.left().node()),
          g.UseRegister(mright.right().node()));
     return;
   }
   VisitRRR(this, kArmVaddF64, node);
 }
 
-
-void InstructionSelector::VisitFloat32Sub(Node* node) {
-  ArmOperandGenerator g(this);
+namespace {
+void VisitFloat32SubHelper(InstructionSelector* selector, Node* node,

[titzer, 2016/05/12 13:02:47]

If you only factor out the part of the helper related to the common case, then
no boolean flag is needed.

+                           bool preserveNan) {
+  ArmOperandGenerator g(selector);
   Float32BinopMatcher m(node);
-  if (m.left().IsMinusZero()) {
-    Emit(kArmVnegF32, g.DefineAsRegister(node),
-         g.UseRegister(m.right().node()));
+  if (!preserveNan && m.left().IsMinusZero()) {
+    selector->Emit(kArmVnegF32, g.DefineAsRegister(node),
+                   g.UseRegister(m.right().node()));
     return;
   }
-  if (m.right().IsFloat32Mul() && CanCover(node, m.right().node())) {
+  if (m.right().IsFloat32Mul() && selector->CanCover(node, m.right().node())) {
     Float32BinopMatcher mright(m.right().node());
-    Emit(kArmVmlsF32, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
-         g.UseRegister(mright.left().node()),
-         g.UseRegister(mright.right().node()));
+    selector->Emit(kArmVmlsF32, g.DefineSameAsFirst(node),
+                   g.UseRegister(m.left().node()),
+                   g.UseRegister(mright.left().node()),
+                   g.UseRegister(mright.right().node()));
     return;
   }
-  VisitRRR(this, kArmVsubF32, node);
+  VisitRRR(selector, kArmVsubF32, node);
 }
 
-
-void InstructionSelector::VisitFloat64Sub(Node* node) {
-  ArmOperandGenerator g(this);
+void VisitFloat64SubHelper(InstructionSelector* selector, Node* node,
+                           bool preserveNan) {
+  ArmOperandGenerator g(selector);
   Float64BinopMatcher m(node);
-  if (m.left().IsMinusZero()) {
+  if (!preserveNan && m.left().IsMinusZero()) {
     if (m.right().IsFloat64RoundDown() &&
-        CanCover(m.node(), m.right().node())) {
+        selector->CanCover(m.node(), m.right().node())) {
       if (m.right().InputAt(0)->opcode() == IrOpcode::kFloat64Sub &&
-          CanCover(m.right().node(), m.right().InputAt(0))) {
+          selector->CanCover(m.right().node(), m.right().InputAt(0))) {
         Float64BinopMatcher mright0(m.right().InputAt(0));
         if (mright0.left().IsMinusZero()) {
-          Emit(kArmVrintpF64, g.DefineAsRegister(node),
-               g.UseRegister(mright0.right().node()));
+          selector->Emit(kArmVrintpF64, g.DefineAsRegister(node),
+                         g.UseRegister(mright0.right().node()));
           return;
         }
       }
     }
-    Emit(kArmVnegF64, g.DefineAsRegister(node),
-         g.UseRegister(m.right().node()));
+    selector->Emit(kArmVnegF64, g.DefineAsRegister(node),
+                   g.UseRegister(m.right().node()));
     return;
   }
-  if (m.right().IsFloat64Mul() && CanCover(node, m.right().node())) {
+  if (m.right().IsFloat64Mul() && selector->CanCover(node, m.right().node())) {
     Float64BinopMatcher mright(m.right().node());
-    Emit(kArmVmlsF64, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
-         g.UseRegister(mright.left().node()),
-         g.UseRegister(mright.right().node()));
+    selector->Emit(kArmVmlsF64, g.DefineSameAsFirst(node),
+                   g.UseRegister(m.left().node()),
+                   g.UseRegister(mright.left().node()),
+                   g.UseRegister(mright.right().node()));
     return;
   }
-  VisitRRR(this, kArmVsubF64, node);
+  VisitRRR(selector, kArmVsubF64, node);
+}
+}  // namespace
+
+void InstructionSelector::VisitFloat32Sub(Node* node) {
+  VisitFloat32SubHelper(this, node, false);
 }
 
+void InstructionSelector::VisitFloat32SubPreserveNan(Node* node) {
+  VisitFloat32SubHelper(this, node, true);
+}
+
+void InstructionSelector::VisitFloat64Sub(Node* node) {
+  VisitFloat64SubHelper(this, node, false);
+}
+
+void InstructionSelector::VisitFloat64SubPreserveNan(Node* node) {
+  VisitFloat64SubHelper(this, node, true);
+}
 
 void InstructionSelector::VisitFloat32Mul(Node* node) {
   VisitRRR(this, kArmVmulF32, node);
 }
 
 
 void InstructionSelector::VisitFloat64Mul(Node* node) {
   VisitRRR(this, kArmVmulF64, node);
 }
 
@@ skipping 622 matching lines @@
              MachineOperatorBuilder::kFloat32Max |
              MachineOperatorBuilder::kFloat64Min |
              MachineOperatorBuilder::kFloat64Max;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8