[objects] seed NumberDictionary (only ia32 now)

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 3356e818922d0ccce2967e4cd2bf6a586917663d..d18b047148e643cd1f3ba5798ac3c3705ff3739b 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -959,6 +959,52 @@ void MacroAssembler::CheckAccessGlobalProxy(Register holder_reg,
 }
 
 
+// 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,
@@ -984,30 +1030,7 @@ void MacroAssembler::LoadFromNumberDictionary(Label* miss,
 
   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));