Fix HConstant's hash function for smis on x64.

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/9466003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10820 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.h

@@ -2457,7 +2457,12 @@ class HConstant: public HTemplateInstruction<0> {
 
   virtual intptr_t Hashcode() {
     ASSERT(!HEAP->allow_allocation(false));
-    return reinterpret_cast<intptr_t>(*handle());
+    intptr_t hash = reinterpret_cast<intptr_t>(*handle());
+    // Prevent smis from having fewer hash values when truncated to
+    // the least significant bits.
+    const int kShiftSize = kSmiShiftSize + kSmiTagSize;
+    STATIC_ASSERT(kShiftSize != 0);
+    return hash ^ (hash >> kShiftSize);
   }
 
 #ifdef DEBUG

test/mjsunit/mjsunit.status

@@ -66,7 +66,7 @@ debug-liveedit-check-stack: SKIP
 debug-liveedit-patch-positions-replace: SKIP
 
 # Test Crankshaft compilation time.  Expected to take too long in debug mode.
-regress/regress-1969: PASS, SKIP if ($mode == debug || $arch == x64)
+regress/regress-1969: PASS, SKIP if $mode == debug
 
 ##############################################################################
 [ $isolates ]

test/mjsunit/regress/regress-1969.js

@@ -31,12 +31,14 @@ f();
 f();
 %OptimizeFunctionOnNextCall(f);
 var start = (new Date()).getTime();
-f();
+var array = f();
 var end = (new Date()).getTime();
 
 // Assert that recompiling and executing f() takes less than a second.
 assertTrue((end - start) < 1000);
 
+for (var i = 0; i < 5000; i++) assertEquals(0, array[i]);
+
 function f() {
   var a = new Array(5000);
   a[0]=0;
@@ -162,7 +164,7 @@ function f() {
   a[120]=0;
   a[121]=0;
   a[122]=0;
-  a[0]=0;
+  a[123]=0;
   a[124]=0;
   a[125]=0;
   a[126]=0;
@@ -1162,7 +1164,7 @@ function f() {
   a[1120]=0;
   a[1121]=0;
   a[1122]=0;
-  a[10]=0;
+  a[1123]=0;
   a[1124]=0;
   a[1125]=0;
   a[1126]=0;
@@ -1269,16 +1271,16 @@ function f() {
   a[1227]=0;
   a[1228]=0;
   a[1229]=0;
-  a[00]=0;
-  a[01]=0;
-  a[02]=0;
-  a[03]=0;
-  a[04]=0;
-  a[05]=0;
-  a[06]=0;
-  a[07]=0;
-  a[08]=0;
-  a[09]=0;
+  a[1230]=0;
+  a[1231]=0;
+  a[1232]=0;
+  a[1233]=0;
+  a[1234]=0;
+  a[1235]=0;
+  a[1236]=0;
+  a[1237]=0;
+  a[1238]=0;
+  a[1239]=0;
   a[1240]=0;
   a[1241]=0;
   a[1242]=0;
@@ -2162,7 +2164,7 @@ function f() {
   a[2120]=0;
   a[2121]=0;
   a[2122]=0;
-  a[20]=0;
+  a[2123]=0;
   a[2124]=0;
   a[2125]=0;
   a[2126]=0;
@@ -3162,7 +3164,7 @@ function f() {
   a[3120]=0;
   a[3121]=0;
   a[3122]=0;
-  a[30]=0;
+  a[3123]=0;
   a[3124]=0;
   a[3125]=0;
   a[3126]=0;
@@ -4162,7 +4164,7 @@ function f() {
   a[4120]=0;
   a[4121]=0;
   a[4122]=0;
-  a[40]=0;
+  a[4123]=0;
   a[4124]=0;
   a[4125]=0;
   a[4126]=0;
@@ -5039,4 +5041,5 @@ function f() {
   a[4997]=0;
   a[4998]=0;
   a[4999]=0;
+  return a;
 }