Use Copy-on-write arrays for cached regexp results.

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index 1885182287f70b34dd4a16a7fa73193b4bf8ae1b..5c84d7e736c0c859b7df5d0e5b80e29f4ce4840d 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -4800,8 +4800,10 @@ void DeferredRegExpLiteral::Generate() {
 
 class DeferredAllocateInNewSpace: public DeferredCode {
  public:
-  DeferredAllocateInNewSpace(int size, Register target)
-    : size_(size), target_(target) {
+  DeferredAllocateInNewSpace(int size,
+                             Register target,
+                             int registers_to_save = 0)
+    : size_(size), target_(target), registers_to_save_(registers_to_save) {
     ASSERT(size >= kPointerSize && size <= Heap::MaxObjectSizeInNewSpace());
     set_comment("[ DeferredAllocateInNewSpace");
   }
@@ -4810,15 +4812,28 @@ class DeferredAllocateInNewSpace: public DeferredCode {
  private:
   int size_;
   Register target_;
+  int registers_to_save_;
 };
 
 
 void DeferredAllocateInNewSpace::Generate() {
+  for (int i = 0; i < kNumRegs; i++) {
+    if (registers_to_save_ & (1 << i)) {
+      Register save_register = { i };
+      __ push(save_register);
+    }
+  }
   __ Push(Smi::FromInt(size_));
   __ CallRuntime(Runtime::kAllocateInNewSpace, 1);
   if (!target_.is(rax)) {
     __ movq(target_, rax);
   }
+  for (int i = kNumRegs - 1; i >= 0; i--) {
+    if (registers_to_save_ & (1 << i)) {
+      Register save_register = { i };
+      __ push(save_register);

[Vitaly Repeshko, 2010/08/20 13:29:49]

push -> pop.

[Lasse Reichstein, 2010/08/23 12:52:11]

Double-doh!
Fixed, for real.

+    }
+  }
 }
 
 
@@ -6606,6 +6621,79 @@ void CodeGenerator::GenerateRegExpConstructResult(ZoneList<Expression*>* args) {
 }
 
 
+void CodeGenerator::GenerateRegExpCloneResult(ZoneList<Expression*>* args) {
+  ASSERT_EQ(1, args->length());
+
+  Load(args->at(0));
+  Result object_result = frame_->Pop();
+  object_result.ToRegister(rax);
+  object_result.Unuse();
+  {
+    VirtualFrame::SpilledScope spilled_scope;
+
+    Label done;
+    __ JumpIfSmi(rax, &done);
+
+    // Load JSRegExpResult map into rdx.
+    // Arguments to this function should be results of calling RegExp exec,
+    // which is either an unmodified JSRegExpResult or null. Anything not having
+    // the unmodified JSRegExpResult map is returned unmodified.
+    // This also ensures that elements are fast.
+
+    __ movq(rdx, ContextOperand(rsi, Context::GLOBAL_INDEX));
+    __ movq(rdx, FieldOperand(rdx, GlobalObject::kGlobalContextOffset));
+    __ movq(rdx, ContextOperand(rdx, Context::REGEXP_RESULT_MAP_INDEX));
+    __ cmpq(rdx, FieldOperand(rax, HeapObject::kMapOffset));
+    __ j(not_equal, &done);
+
+    DeferredAllocateInNewSpace* allocate_fallback =
+        new DeferredAllocateInNewSpace(JSRegExpResult::kSize,
+                                       rbx,
+                                       rdx.bit() | rax.bit());
+
+    // All set, copy the contents to a new object.
+    __ AllocateInNewSpace(JSRegExpResult::kSize,
+                          rbx,
+                          no_reg,
+                          no_reg,
+                          allocate_fallback->entry_label(),
+                          TAG_OBJECT);
+    __ bind(allocate_fallback->exit_label());
+
+    STATIC_ASSERT(JSRegExpResult::kSize % (2 * kPointerSize) == 0);
+    // There is an even number of fields, so unroll the loop once
+    // for efficiency.
+    for (int i = 0; i < JSRegExpResult::kSize; i += 2 * kPointerSize) {
+      STATIC_ASSERT(JSObject::kMapOffset % (2 * kPointerSize) == 0);
+      if (i != JSObject::kMapOffset) {
+        // The map was already loaded into edx.
+        __ movq(rdx, FieldOperand(rax, i));
+      }
+      __ movq(rcx, FieldOperand(rax, i + kPointerSize));
+
+      STATIC_ASSERT(JSObject::kElementsOffset % (2 * kPointerSize) == 0);
+      if (i == JSObject::kElementsOffset) {
+        // If the elements array isn't empty, make it copy-on-write
+        // before copying it.
+        Label empty;
+        __ CompareRoot(rdx, Heap::kEmptyFixedArrayRootIndex);
+        __ j(equal, &empty);
+        ASSERT(!Heap::InNewSpace(Heap::fixed_cow_array_map()));
+        __ LoadRoot(kScratchRegister, Heap::kFixedCOWArrayMapRootIndex);
+        __ movq(FieldOperand(rdx, HeapObject::kMapOffset), kScratchRegister);
+        __ bind(&empty);
+      }
+      __ movq(FieldOperand(rbx, i), rdx);
+      __ movq(FieldOperand(rbx, i + kPointerSize), rcx);
+    }
+    __ movq(rax, rbx);
+
+    __ bind(&done);
+  }
+  frame_->Push(rax);
+}
+
+
 class DeferredSearchCache: public DeferredCode {
  public:
   DeferredSearchCache(Register dst,