Fix uninitialized FixedArray potentially being left behind by...

Fix uninitialized FixedArray potentially being left behind by ElementsTransitionGenerator::GenerateDoubleToObject

BUG=chromium:421843
LOG=n
R=ishell@chromium.org

Review URL: https://codereview.chromium.org/636313003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24498 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/codegen-arm.cc

@@ -604,8 +604,22 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   __ add(src_elements, elements,
          Operand(FixedDoubleArray::kHeaderSize - kHeapObjectTag + 4));
   __ add(dst_elements, array, Operand(FixedArray::kHeaderSize));
-  __ add(array, array, Operand(kHeapObjectTag));
   __ add(dst_end, dst_elements, Operand(length, LSL, 1));
+
+  // Allocating heap numbers in the loop below can fail and cause a jump to
+  // gc_required. We can't leave a partly initialized FixedArray behind,
+  // so pessimistically fill it with holes now.
+  Label initialization_loop, initialization_loop_entry;
+  __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
+  __ b(&initialization_loop_entry);
+  __ bind(&initialization_loop);
+  __ str(scratch, MemOperand(dst_elements, kPointerSize, PostIndex));
+  __ bind(&initialization_loop_entry);
+  __ cmp(dst_elements, dst_end);
+  __ b(lt, &initialization_loop);
+
+  __ add(dst_elements, array, Operand(FixedArray::kHeaderSize));
+  __ add(array, array, Operand(kHeapObjectTag));
   __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
   // Using offsetted addresses in src_elements to fully take advantage of
   // post-indexing.

src/arm64/codegen-arm64.cc

@@ -290,15 +290,28 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   Register src_elements = x10;
   Register dst_elements = x11;
   Register dst_end = x12;
+  Register the_hole = x14;
+  __ LoadRoot(the_hole, Heap::kTheHoleValueRootIndex);
   __ Add(src_elements, elements,
          FixedDoubleArray::kHeaderSize - kHeapObjectTag);
   __ Add(dst_elements, array, FixedArray::kHeaderSize);
-  __ Add(array, array, kHeapObjectTag);
   __ Add(dst_end, dst_elements, Operand(length, LSL, kPointerSizeLog2));
 
-  Register the_hole = x14;
+  // Allocating heap numbers in the loop below can fail and cause a jump to
+  // gc_required. We can't leave a partly initialized FixedArray behind,
+  // so pessimistically fill it with holes now.
+  Label initialization_loop, initialization_loop_entry;
+  __ B(&initialization_loop_entry);
+  __ bind(&initialization_loop);
+  __ Str(the_hole, MemOperand(dst_elements, kPointerSize, PostIndex));
+  __ bind(&initialization_loop_entry);
+  __ Cmp(dst_elements, dst_end);
+  __ B(lt, &initialization_loop);
+
+  __ Add(dst_elements, array, FixedArray::kHeaderSize);
+  __ Add(array, array, kHeapObjectTag);
+
   Register heap_num_map = x15;
-  __ LoadRoot(the_hole, Heap::kTheHoleValueRootIndex);
   __ LoadRoot(heap_num_map, Heap::kHeapNumberMapRootIndex);
 
   Label entry;

src/ia32/codegen-ia32.cc

@@ -720,6 +720,19 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   __ mov(FieldOperand(eax, FixedArray::kLengthOffset), ebx);
   __ mov(edi, FieldOperand(edx, JSObject::kElementsOffset));
 
+  // Allocating heap numbers in the loop below can fail and cause a jump to
+  // gc_required. We can't leave a partly initialized FixedArray behind,
+  // so pessimistically fill it with holes now.
+  Label initialization_loop, initialization_loop_entry;
+  __ jmp(&initialization_loop_entry, Label::kNear);
+  __ bind(&initialization_loop);
+  __ mov(FieldOperand(eax, ebx, times_2, FixedArray::kHeaderSize),
+         masm->isolate()->factory()->the_hole_value());
+  __ bind(&initialization_loop_entry);
+  __ sub(ebx, Immediate(Smi::FromInt(1)));
+  __ j(not_sign, &initialization_loop);
+
+  __ mov(ebx, FieldOperand(edi, FixedDoubleArray::kLengthOffset));
   __ jmp(&entry);
 
   // ebx: target map

src/runtime/runtime-test.cc

@@ -247,7 +247,9 @@ RUNTIME_FUNCTION(Runtime_GlobalPrint) {
 
 
 RUNTIME_FUNCTION(Runtime_SystemBreak) {
-  SealHandleScope shs(isolate);
+  // The code below doesn't create handles, but when breaking here in GDB
+  // having a handle scope might be useful.
+  HandleScope scope(isolate);
   DCHECK(args.length() == 0);
   base::OS::DebugBreak();
   return isolate->heap()->undefined_value();

src/x64/codegen-x64.cc

@@ -397,6 +397,20 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   __ LoadRoot(rdi, Heap::kTheHoleValueRootIndex);
   // rsi: the-hole NaN
   // rdi: pointer to the-hole
+
+  // Allocating heap numbers in the loop below can fail and cause a jump to
+  // gc_required. We can't leave a partly initialized FixedArray behind,
+  // so pessimistically fill it with holes now.
+  Label initialization_loop, initialization_loop_entry;
+  __ jmp(&initialization_loop_entry, Label::kNear);
+  __ bind(&initialization_loop);
+  __ movp(FieldOperand(r11, r9, times_pointer_size, FixedArray::kHeaderSize),
+          rdi);
+  __ bind(&initialization_loop_entry);
+  __ decp(r9);
+  __ j(not_sign, &initialization_loop);
+
+  __ SmiToInteger32(r9, FieldOperand(r8, FixedDoubleArray::kLengthOffset));
   __ jmp(&entry);
 
   // Call into runtime if GC is required.