Fix Smi-based MathMinMax on x64, and reenable smi mode.

BUG=
R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/20706002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15905 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -4792,8 +4792,7 @@ class HMathMinMax: public HArithmeticBinaryOperation {
   virtual Representation RepresentationFromInputs() {
     Representation left_rep = left()->representation();
     Representation right_rep = right()->representation();
-    // TODO(verwaest): Initialize to Smi once lithium-codegen has been fixed.
-    Representation result = Representation::Integer32();
+    Representation result = Representation::Smi();
     result = result.generalize(left_rep);
     result = result.generalize(right_rep);
     if (result.IsTagged()) return Representation::Double();

src/x64/lithium-codegen-x64.cc

@@ -1699,7 +1699,7 @@ void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
   LOperand* right = instr->right();
   ASSERT(left->Equals(instr->result()));
   HMathMinMax::Operation operation = instr->hydrogen()->operation();
-  if (instr->hydrogen()->representation().IsInteger32()) {
+  if (instr->hydrogen()->representation().IsSmiOrInteger32()) {
     Label return_left;
     Condition condition = (operation == HMathMinMax::kMathMin)
         ? less_equal
@@ -1708,17 +1708,26 @@ void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
     if (right->IsConstantOperand()) {
       Immediate right_imm =
           Immediate(ToInteger32(LConstantOperand::cast(right)));
+      ASSERT(!instr->hydrogen_value()->representation().IsSmi());
       __ cmpl(left_reg, right_imm);
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_imm);
     } else if (right->IsRegister()) {
       Register right_reg = ToRegister(right);
-      __ cmpl(left_reg, right_reg);
+      if (instr->hydrogen_value()->representation().IsSmi()) {
+        __ cmpq(left_reg, right_reg);
+      } else {
+        __ cmpl(left_reg, right_reg);
+      }
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_reg);
     } else {
       Operand right_op = ToOperand(right);
-      __ cmpl(left_reg, right_op);
+      if (instr->hydrogen_value()->representation().IsSmi()) {
+        __ cmpq(left_reg, right_op);
+      } else {
+        __ cmpl(left_reg, right_op);
+      }
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_op);
     }

src/x64/lithium-x64.cc

@@ -1562,9 +1562,9 @@ LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
 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());
+  if (instr->representation().IsSmiOrInteger32()) {
+    ASSERT(instr->left()->representation().Equals(instr->representation()));
+    ASSERT(instr->right()->representation().Equals(instr->representation()));
     left = UseRegisterAtStart(instr->BetterLeftOperand());
     right = UseOrConstantAtStart(instr->BetterRightOperand());
   } else {

test/mjsunit/math-min-max.js

@@ -177,6 +177,21 @@ function crankshaft_test_2() {
 
 run(crankshaft_test_2);
 
+var o = { a: 1, b: 2 };
+
+// Test smi-based Math.min.
+function f(o) {
+  return Math.min(o.a, o.b);
+}
+
+assertEquals(1, f(o));
+assertEquals(1, f(o));
+%OptimizeFunctionOnNextCall(f);
+assertEquals(1, f(o));
+o.a = 5;
+o.b = 4;
+assertEquals(4, f(o));
+
 // Test overriding Math.min and Math.max
 Math.min = function(a, b) { return a + b; }
 Math.max = function(a, b) { return a - b; }