MIPS: [turbofan] Optimize fpu compares with zero literal.

src/compiler/mips/instruction-selector-mips.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 781 matching lines @@
     DCHECK(cont->IsSet());
     selector->Emit(opcode, g.DefineAsRegister(cont->result()), left, right);
   }
 }
 
 
 // Shared routine for multiple float32 compare operations.
 void VisitFloat32Compare(InstructionSelector* selector, Node* node,
                          FlagsContinuation* cont) {
   MipsOperandGenerator g(selector);
-  Node* left = node->InputAt(0);
-  Node* right = node->InputAt(1);
-  VisitCompare(selector, kMipsCmpS, g.UseRegister(left), g.UseRegister(right),
-               cont);
+  Float32BinopMatcher m(node);
+  InstructionOperand lhs, rhs;
+
+  lhs = m.left().IsZero() ? g.UseImmediate(m.left().node())
+                          : g.UseRegister(m.left().node());
+  rhs = m.right().IsZero() ? g.UseImmediate(m.right().node())
+                           : g.UseRegister(m.right().node());
+  VisitCompare(selector, kMipsCmpS, lhs, rhs, cont);
 }
 
 
 // Shared routine for multiple float64 compare operations.
 void VisitFloat64Compare(InstructionSelector* selector, Node* node,
                          FlagsContinuation* cont) {
   MipsOperandGenerator g(selector);
-  Node* left = node->InputAt(0);
-  Node* right = node->InputAt(1);
-  VisitCompare(selector, kMipsCmpD, g.UseRegister(left), g.UseRegister(right),
-               cont);
+  Float64BinopMatcher m(node);
+  InstructionOperand lhs, rhs;
+
+  lhs = m.left().IsZero() ? g.UseImmediate(m.left().node())
+                          : g.UseRegister(m.left().node());
+  rhs = m.right().IsZero() ? g.UseImmediate(m.right().node())
+                           : g.UseRegister(m.right().node());
+  VisitCompare(selector, kMipsCmpD, lhs, rhs, cont);
 }
 
 
 // Shared routine for multiple word compare operations.
 void VisitWordCompare(InstructionSelector* selector, Node* node,
                       InstructionCode opcode, FlagsContinuation* cont,
                       bool commutative) {
   MipsOperandGenerator g(selector);
   Node* left = node->InputAt(0);
   Node* right = node->InputAt(1);
@@ skipping 321 matching lines @@
       IsFp64Mode()) {
     flags |= MachineOperatorBuilder::kFloat64RoundDown |
              MachineOperatorBuilder::kFloat64RoundTruncate;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8