Changed hash table to use more of the hash value when probing.

src/arm/ic-arm.cc

Index: src/arm/ic-arm.cc
===================================================================
--- src/arm/ic-arm.cc	(revision 2481)
+++ src/arm/ic-arm.cc	(working copy)
@@ -103,15 +103,16 @@
   // Generate an unrolled loop that performs a few probes before
   // giving up. Measurements done on Gmail indicate that 2 probes
   // cover ~93% of loads from dictionaries.
-  static const int kProbes = 4;
-  for (int i = 0; i < kProbes; i++) {
-    // Compute the masked index: (hash + i + i * i) & mask.
+  static const uint32_t kProbes =
+      HashTable<StringDictionaryShape, String*>::kNofFastProbes;
+  static const uint32_t kShift =
+      HashTable<StringDictionaryShape, String*>::kHashRotateShift;
+
+  for (uint32_t i = 0; i < kProbes; i++) {
+    // Compute the masked index.
     __ ldr(t1, FieldMemOperand(r2, String::kLengthOffset));
     __ mov(t1, Operand(t1, LSR, String::kHashShift));
-    if (i > 0) {
-      __ add(t1, t1, Operand(StringDictionary::GetProbeOffset(i)));
-    }
-    __ and_(t1, t1, Operand(r3));
+    __ and_(t1, r3, Operand(t1, ROR, (kShift * i) % kBitsPerInt));

[Kasper Lund, 2009/07/16 12:41:43]

Maybe this needs to be guarded with something like i > 0, becuase I'm not sure
ROR is legal with a count of zero on ARM.

[bak, 2009/07/16 12:52:41]

Fixed, good catch.

 
     // Scale the index by multiplying by the element size.
     ASSERT(StringDictionary::kEntrySize == 3);