Bias commutative single-use register inputs and support lea adds

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index a6f0466b7ad75c0d38982f3ba6dfc4e2ea4ecbda..41cc77a06b2e31a843db2c6b2d65a1b2d198348d 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -782,8 +782,8 @@ LInstruction* LChunkBuilder::DoArithmeticD(Token::Value op,
   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);
 }
@@ -1309,8 +1309,8 @@ LInstruction* LChunkBuilder::DoBitwise(HBitwise* 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());
+    LOperand* right = UseOrConstantAtStart(instr->BetterRightOperand());
     return DefineSameAsFirst(new(zone()) LBitI(left, right));
   } else {
     ASSERT(instr->representation().IsTagged());
@@ -1473,8 +1473,8 @@ 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)) {
@@ -1513,12 +1513,29 @@ LInstruction* LChunkBuilder::DoSub(HSub* 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 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);
+    bool can_overflow = instr->CheckFlag(HValue::kCanOverflow);
+    LInstruction* result = NULL;
+    if (use_lea) {
+      result = DefineAsRegister(add);
+    } else {
+      result = DefineSameAsFirst(add);
+    }
+    if (can_overflow) {
+      result = AssignEnvironment(result);
+    }
     if (instr->CheckFlag(HValue::kCanOverflow)) {

[Jakob Kummerow, 2013/05/07 11:53:58]

This condition is now a dupe of the above.

[danno, 2013/05/08 08:37:18]

Done.

       result = AssignEnvironment(result);
     }
@@ -1539,8 +1556,8 @@ LInstruction* LChunkBuilder::DoMathMinMax(HMathMinMax* instr) {
   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());