[x86] Select better left operand for comparisons.

src/compiler/ia32/instruction-selector-ia32.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/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 630 matching lines @@
   InstructionOperand** first_output =
       buffer.outputs.size() > 0 ? &buffer.outputs.front() : NULL;
   Instruction* call_instr =
       Emit(opcode, buffer.outputs.size(), first_output,
            buffer.instruction_args.size(), &buffer.instruction_args.front());
   call_instr->MarkAsCall();
 }
 
 
 // Shared routine for multiple compare operations.
-static inline void VisitCompare(InstructionSelector* selector,
-                                InstructionCode opcode,
-                                InstructionOperand* left,
-                                InstructionOperand* right,
-                                FlagsContinuation* cont) {
+static void VisitCompare(InstructionSelector* selector, InstructionCode opcode,
+                         InstructionOperand* left, InstructionOperand* right,
+                         FlagsContinuation* cont) {
   IA32OperandGenerator g(selector);
   if (cont->IsBranch()) {
     selector->Emit(cont->Encode(opcode), NULL, left, right,
                    g.Label(cont->true_block()),
                    g.Label(cont->false_block()))->MarkAsControl();
   } else {
     DCHECK(cont->IsSet());
     // TODO(titzer): Needs byte register.
     selector->Emit(cont->Encode(opcode), g.DefineAsRegister(cont->result()),
                    left, right);
   }
 }
 
 
+// Shared routine for multiple compare operations.
+static void VisitCompare(InstructionSelector* selector, InstructionCode opcode,
+                         Node* left, Node* right, FlagsContinuation* cont,
+                         bool commutative) {
+  IA32OperandGenerator g(selector);
+  if (commutative && g.CanBeBetterLeftOperand(right)) {
+    std::swap(left, right);
+  }
+  VisitCompare(selector, opcode, g.UseRegister(left), g.Use(right), cont);
+}
+
+
 // Shared routine for multiple word compare operations.
-static inline void VisitWordCompare(InstructionSelector* selector, Node* node,
-                                    InstructionCode opcode,
-                                    FlagsContinuation* cont, bool commutative) {
+static void VisitWordCompare(InstructionSelector* selector, Node* node,
+                             InstructionCode opcode, FlagsContinuation* cont) {
   IA32OperandGenerator g(selector);
-  Node* left = node->InputAt(0);
-  Node* right = node->InputAt(1);
+  Node* const left = node->InputAt(0);
+  Node* const right = node->InputAt(1);
 
   // Match immediates on left or right side of comparison.
   if (g.CanBeImmediate(right)) {
     VisitCompare(selector, opcode, g.Use(left), g.UseImmediate(right), cont);
   } else if (g.CanBeImmediate(left)) {
-    if (!commutative) cont->Commute();
+    if (!node->op()->HasProperty(Operator::kCommutative)) cont->Commute();
     VisitCompare(selector, opcode, g.Use(right), g.UseImmediate(left), cont);
   } else {
-    VisitCompare(selector, opcode, g.UseRegister(left), g.Use(right), cont);
+    VisitCompare(selector, opcode, left, right, cont,
+                 node->op()->HasProperty(Operator::kCommutative));
   }
 }
 
 
 // Shared routine for multiple float compare operations.
 static void VisitFloat64Compare(InstructionSelector* selector, Node* node,
                                 FlagsContinuation* cont) {
-  IA32OperandGenerator g(selector);
-  Node* left = node->InputAt(0);
-  Node* right = node->InputAt(1);
-  VisitCompare(selector, kSSEFloat64Cmp, g.UseRegister(left), g.Use(right),
-               cont);
+  VisitCompare(selector, kSSEFloat64Cmp, node->InputAt(0), node->InputAt(1),
+               cont, node->op()->HasProperty(Operator::kCommutative));
 }
 
 
 void InstructionSelector::VisitBranch(Node* branch, BasicBlock* tbranch,
                                       BasicBlock* fbranch) {
   IA32OperandGenerator g(this);
   Node* user = branch;
   Node* value = branch->InputAt(0);
 
   FlagsContinuation cont(kNotEqual, tbranch, fbranch);
@@ skipping 14 matching lines @@
     } else {
       break;
     }
   }
 
   // Try to combine the branch with a comparison.
   if (CanCover(user, value)) {
     switch (value->opcode()) {
       case IrOpcode::kWord32Equal:
         cont.OverwriteAndNegateIfEqual(kEqual);
-        return VisitWordCompare(this, value, kIA32Cmp, &cont, false);
+        return VisitWordCompare(this, value, kIA32Cmp, &cont);
       case IrOpcode::kInt32LessThan:
         cont.OverwriteAndNegateIfEqual(kSignedLessThan);
-        return VisitWordCompare(this, value, kIA32Cmp, &cont, false);
+        return VisitWordCompare(this, value, kIA32Cmp, &cont);
       case IrOpcode::kInt32LessThanOrEqual:
         cont.OverwriteAndNegateIfEqual(kSignedLessThanOrEqual);
-        return VisitWordCompare(this, value, kIA32Cmp, &cont, false);
+        return VisitWordCompare(this, value, kIA32Cmp, &cont);
       case IrOpcode::kUint32LessThan:
         cont.OverwriteAndNegateIfEqual(kUnsignedLessThan);
-        return VisitWordCompare(this, value, kIA32Cmp, &cont, false);
+        return VisitWordCompare(this, value, kIA32Cmp, &cont);
       case IrOpcode::kUint32LessThanOrEqual:
         cont.OverwriteAndNegateIfEqual(kUnsignedLessThanOrEqual);
-        return VisitWordCompare(this, value, kIA32Cmp, &cont, false);
+        return VisitWordCompare(this, value, kIA32Cmp, &cont);
       case IrOpcode::kFloat64Equal:
         cont.OverwriteAndNegateIfEqual(kUnorderedEqual);
         return VisitFloat64Compare(this, value, &cont);
       case IrOpcode::kFloat64LessThan:
         cont.OverwriteAndNegateIfEqual(kUnorderedLessThan);
         return VisitFloat64Compare(this, value, &cont);
       case IrOpcode::kFloat64LessThanOrEqual:
         cont.OverwriteAndNegateIfEqual(kUnorderedLessThanOrEqual);
         return VisitFloat64Compare(this, value, &cont);
       case IrOpcode::kProjection:
@@ skipping 15 matching lines @@
               case IrOpcode::kInt32SubWithOverflow:
                 cont.OverwriteAndNegateIfEqual(kOverflow);
                 return VisitBinop(this, node, kIA32Sub, &cont);
               default:
                 break;
             }
           }
         }
         break;
       case IrOpcode::kInt32Sub:
-        return VisitWordCompare(this, value, kIA32Cmp, &cont, false);
+        return VisitWordCompare(this, value, kIA32Cmp, &cont);
       case IrOpcode::kWord32And:
-        return VisitWordCompare(this, value, kIA32Test, &cont, true);
+        return VisitWordCompare(this, value, kIA32Test, &cont);
       default:
         break;
     }
   }
 
   // Branch could not be combined with a compare, emit compare against 0.
   VisitCompare(this, kIA32Cmp, g.Use(value), g.TempImmediate(0), &cont);
 }
 
 
 void InstructionSelector::VisitWord32Equal(Node* const node) {
   Node* const user = node;
   FlagsContinuation cont(kEqual, node);
   Int32BinopMatcher m(user);
   if (m.right().Is(0)) {
     Node* const value = m.left().node();
     if (CanCover(user, value)) {
       switch (value->opcode()) {
         case IrOpcode::kInt32Sub:
-          return VisitWordCompare(this, value, kIA32Cmp, &cont, false);
+          return VisitWordCompare(this, value, kIA32Cmp, &cont);
         case IrOpcode::kWord32And:
-          return VisitWordCompare(this, value, kIA32Test, &cont, true);
+          return VisitWordCompare(this, value, kIA32Test, &cont);
         default:
           break;
       }
     }
   }
-  return VisitWordCompare(this, node, kIA32Cmp, &cont, false);
+  VisitWordCompare(this, node, kIA32Cmp, &cont);
 }
 
 
 void InstructionSelector::VisitInt32LessThan(Node* node) {
   FlagsContinuation cont(kSignedLessThan, node);
-  return VisitWordCompare(this, node, kIA32Cmp, &cont, false);
+  VisitWordCompare(this, node, kIA32Cmp, &cont);
 }
 
 
 void InstructionSelector::VisitInt32LessThanOrEqual(Node* node) {
   FlagsContinuation cont(kSignedLessThanOrEqual, node);
-  return VisitWordCompare(this, node, kIA32Cmp, &cont, false);
+  VisitWordCompare(this, node, kIA32Cmp, &cont);
 }
 
 
 void InstructionSelector::VisitUint32LessThan(Node* node) {
   FlagsContinuation cont(kUnsignedLessThan, node);
-  return VisitWordCompare(this, node, kIA32Cmp, &cont, false);
+  VisitWordCompare(this, node, kIA32Cmp, &cont);
 }
 
 
 void InstructionSelector::VisitUint32LessThanOrEqual(Node* node) {
   FlagsContinuation cont(kUnsignedLessThanOrEqual, node);
-  return VisitWordCompare(this, node, kIA32Cmp, &cont, false);
+  VisitWordCompare(this, node, kIA32Cmp, &cont);
 }
 
 
 void InstructionSelector::VisitInt32AddWithOverflow(Node* node) {
   if (Node* ovf = node->FindProjection(1)) {
     FlagsContinuation cont(kOverflow, ovf);
     return VisitBinop(this, node, kIA32Add, &cont);
   }
   FlagsContinuation cont;
   VisitBinop(this, node, kIA32Add, &cont);
@@ skipping 23 matching lines @@
 
 
 void InstructionSelector::VisitFloat64LessThanOrEqual(Node* node) {
   FlagsContinuation cont(kUnorderedLessThanOrEqual, node);
   VisitFloat64Compare(this, node, &cont);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8