Bias commutative single-use register inputs and support lea adds

src/x64/lithium-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 764 matching lines @@
   return does_deopt ? AssignEnvironment(result) : result;
 }
 
 
 LInstruction* LChunkBuilder::DoArithmeticD(Token::Value op,
                                            HArithmeticBinaryOperation* instr) {
   ASSERT(instr->representation().IsDouble());
   ASSERT(instr->left()->representation().IsDouble());
   ASSERT(instr->right()->representation().IsDouble());
   ASSERT(op != Token::MOD);
-  LOperand* left = UseRegisterAtStart(instr->left());
-  LOperand* right = UseRegisterAtStart(instr->right());
+  LOperand* left = UseRegisterAtStart(instr->BetterLeftOperand());
+  LOperand* right = UseRegisterAtStart(instr->BetterRightOperand());
   LArithmeticD* result = new(zone()) LArithmeticD(op, left, right);
   return DefineSameAsFirst(result);
 }
 
 
 LInstruction* LChunkBuilder::DoArithmeticT(Token::Value op,
                                            HArithmeticBinaryOperation* instr) {
   ASSERT(op == Token::ADD ||
          op == Token::DIV ||
          op == Token::MOD ||
@@ skipping 505 matching lines @@
 LInstruction* LChunkBuilder::DoShl(HShl* instr) {
   return DoShift(Token::SHL, instr);
 }
 
 
 LInstruction* LChunkBuilder::DoBitwise(HBitwise* instr) {
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
 
-    LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
-    LOperand* right = UseOrConstantAtStart(instr->MostConstantOperand());
+    LOperand* left = UseRegisterAtStart(instr->BetterLeftOperand());
+    LOperand* right = UseOrConstantAtStart(instr->BetterRightOperand());
     return DefineSameAsFirst(new(zone()) LBitI(left, right));
   } else {
     ASSERT(instr->representation().IsTagged());
     ASSERT(instr->left()->representation().IsTagged());
     ASSERT(instr->right()->representation().IsTagged());
 
     LOperand* left = UseFixed(instr->left(), rdx);
     LOperand* right = UseFixed(instr->right(), rax);
     LArithmeticT* result = new(zone()) LArithmeticT(instr->op(), left, right);
     return MarkAsCall(DefineFixed(result, rax), instr);
@@ skipping 142 matching lines @@
     LArithmeticD* result = new(zone()) LArithmeticD(Token::MOD, left, right);
     return MarkAsCall(DefineFixedDouble(result, xmm1), instr);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoMul(HMul* instr) {
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
-    LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
-    LOperand* right = UseOrConstant(instr->MostConstantOperand());
+    LOperand* left = UseRegisterAtStart(instr->BetterLeftOperand());
+    LOperand* right = UseOrConstant(instr->BetterRightOperand());
     LMulI* mul = new(zone()) LMulI(left, right);
     if (instr->CheckFlag(HValue::kCanOverflow) ||
         instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
       AssignEnvironment(mul);
     }
     return DefineSameAsFirst(mul);
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::MUL, instr);
   } else {
     ASSERT(instr->representation().IsTagged());
@@ skipping 18 matching lines @@
     return DoArithmeticD(Token::SUB, instr);
   } else {
     ASSERT(instr->representation().IsTagged());
     return DoArithmeticT(Token::SUB, instr);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
   if (instr->representation().IsInteger32()) {
+    // Check to see if it would be advantageous to use an lea instruction rather
+    // than an add. This is the case when no overflow check is needed and there
+    // are multiple uses of the add's inputs, so using a 3-register add will
+    // preserve all input values for later uses.
+    bool use_lea = LAddI::UseLea(instr);
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
-    LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
-    LOperand* right = UseOrConstantAtStart(instr->MostConstantOperand());
+    LOperand* left = UseRegisterAtStart(instr->BetterLeftOperand());
+    HValue* right_candidate = instr->BetterRightOperand();
+    LOperand* right = use_lea
+        ? UseRegisterOrConstantAtStart(right_candidate)
+        : UseOrConstantAtStart(right_candidate);
     LAddI* add = new(zone()) LAddI(left, right);
-    LInstruction* result = DefineSameAsFirst(add);
-    if (instr->CheckFlag(HValue::kCanOverflow)) {
+    bool can_overflow = instr->CheckFlag(HValue::kCanOverflow);
+    LInstruction* result = use_lea
+        ? DefineAsRegister(add)
+        : DefineSameAsFirst(add);
+    if (can_overflow) {
       result = AssignEnvironment(result);
     }
     return result;
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::ADD, instr);
   } else {
     ASSERT(instr->representation().IsTagged());
     return DoArithmeticT(Token::ADD, instr);
   }
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoMathMinMax(HMathMinMax* instr) {
   LOperand* left = NULL;
   LOperand* right = NULL;
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
-    left = UseRegisterAtStart(instr->LeastConstantOperand());
-    right = UseOrConstantAtStart(instr->MostConstantOperand());
+    left = UseRegisterAtStart(instr->BetterLeftOperand());
+    right = UseOrConstantAtStart(instr->BetterRightOperand());
   } else {
     ASSERT(instr->representation().IsDouble());
     ASSERT(instr->left()->representation().IsDouble());
     ASSERT(instr->right()->representation().IsDouble());
     left = UseRegisterAtStart(instr->left());
     right = UseRegisterAtStart(instr->right());
   }
   LMathMinMax* minmax = new(zone()) LMathMinMax(left, right);
   return DefineSameAsFirst(minmax);
 }
@@ skipping 1002 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64