[objects] seed NumberDictionary (only ia32 now)

src/ia32/macro-assembler-ia32.cc

 // Copyright 2011 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 941 matching lines @@
                      Context::SECURITY_TOKEN_INDEX * kPointerSize;
   mov(scratch, FieldOperand(scratch, token_offset));
   cmp(scratch, FieldOperand(holder_reg, token_offset));
   pop(holder_reg);
   j(not_equal, miss);
 
   bind(&same_contexts);
 }
 
 
+// Compute the hash code from the untagged key.  This must be kept in sync
+// with ComputeIntegerHash in utils.h.
+//
+// Note: r0 will contain hash code
+void MacroAssembler::GetNumberHash(Register r0, Register scratch) {
+  // First of all we assign the hash seed to scratch.
+  if (Serializer::enabled()) {
+    ExternalReference roots_array_start =
+        ExternalReference::roots_array_start(isolate());
+    mov(scratch, Immediate(Heap::kStringHashSeedRootIndex));
+    mov(scratch, Operand::StaticArray(scratch,
+                                      times_pointer_size,
+                                      roots_array_start));
+  } else {
+    int32_t seed = isolate()->heap()->StringHashSeed();
+    mov(scratch, Immediate(seed));
+  }
+
+  // Xor original key with a seed
+  xor_(r0, scratch);

[Erik Corry, 2012/01/10 11:53:16]

You should move this xor up into the if above, because you can then do it with a
single xor instead of a mov and an xor.

+
+  // hash = ~hash + (hash << 15);
+  mov(scratch, r0);
+  not_(r0);
+  shl(scratch, 15);
+  add(r0, scratch);
+  // hash = hash ^ (hash >> 12);
+  mov(scratch, r0);
+  shr(scratch, 12);
+  xor_(r0, scratch);
+  // hash = hash + (hash << 2);
+  lea(r0, Operand(r0, r0, times_4, 0));
+  // hash = hash ^ (hash >> 4);
+  mov(scratch, r0);
+  shr(scratch, 4);
+  xor_(r0, scratch);
+  // hash = hash * 2057;
+  imul(r0, r0, 2057);
+  // hash = hash ^ (hash >> 16);
+  mov(scratch, r0);
+  shr(scratch, 16);
+  xor_(r0, scratch);
+}
+
+
+
 void MacroAssembler::LoadFromNumberDictionary(Label* miss,
                                               Register elements,
                                               Register key,
                                               Register r0,
                                               Register r1,
                                               Register r2,
                                               Register result) {
   // Register use:
   //
   // elements - holds the slow-case elements of the receiver and is unchanged.
   //
   // key      - holds the smi key on entry and is unchanged.
   //
   // Scratch registers:
   //
   // r0 - holds the untagged key on entry and holds the hash once computed.
   //
   // r1 - used to hold the capacity mask of the dictionary
   //
   // r2 - used for the index into the dictionary.
   //
   // result - holds the result on exit if the load succeeds and we fall through.
 
   Label done;
 
-  // Compute the hash code from the untagged key.  This must be kept in sync
-  // with ComputeIntegerHash in utils.h.
-  //
-  // hash = ~hash + (hash << 15);
-  mov(r1, r0);
-  not_(r0);
-  shl(r1, 15);
-  add(r0, r1);
-  // hash = hash ^ (hash >> 12);
-  mov(r1, r0);
-  shr(r1, 12);
-  xor_(r0, r1);
-  // hash = hash + (hash << 2);
-  lea(r0, Operand(r0, r0, times_4, 0));
-  // hash = hash ^ (hash >> 4);
-  mov(r1, r0);
-  shr(r1, 4);
-  xor_(r0, r1);
-  // hash = hash * 2057;
-  imul(r0, r0, 2057);
-  // hash = hash ^ (hash >> 16);
-  mov(r1, r0);
-  shr(r1, 16);
-  xor_(r0, r1);
+  GetNumberHash(r0, r1);
 
   // Compute capacity mask.
   mov(r1, FieldOperand(elements, NumberDictionary::kCapacityOffset));
   shr(r1, kSmiTagSize);  // convert smi to int
   dec(r1);
 
   // Generate an unrolled loop that performs a few probes before giving up.
   const int kProbes = 4;
   for (int i = 0; i < kProbes; i++) {
     // Use r2 for index calculations and keep the hash intact in r0.
@@ skipping 1664 matching lines @@
     cmp(length, Operand(bitmap_scratch, MemoryChunk::kSizeOffset));
     Check(less_equal, "Live Bytes Count overflow chunk size");
   }
 
   bind(&done);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32