Fix crashes during GC caused by partially initialized objects. The...

src/x64/macro-assembler-x64.cc

 // Copyright 2010 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 1871 matching lines @@
       Context::kHeaderSize + Context::SECURITY_TOKEN_INDEX * kPointerSize;
   movq(scratch, FieldOperand(scratch, token_offset));
   cmpq(scratch, FieldOperand(kScratchRegister, token_offset));
   j(not_equal, miss);
 
   bind(&same_contexts);
 }
 
 
 void MacroAssembler::LoadAllocationTopHelper(Register result,
-                                             Register result_end,
                                              Register scratch,
                                              AllocationFlags flags) {
   ExternalReference new_space_allocation_top =
       ExternalReference::new_space_allocation_top_address();
 
   // Just return if allocation top is already known.
   if ((flags & RESULT_CONTAINS_TOP) != 0) {
     // No use of scratch if allocation top is provided.
     ASSERT(!scratch.is_valid());
 #ifdef DEBUG
     // Assert that result actually contains top on entry.
     movq(kScratchRegister, new_space_allocation_top);
     cmpq(result, Operand(kScratchRegister, 0));
     Check(equal, "Unexpected allocation top");
 #endif
     return;
   }
 
   // Move address of new object to result. Use scratch register if available,
   // and keep address in scratch until call to UpdateAllocationTopHelper.
   if (scratch.is_valid()) {
-    ASSERT(!scratch.is(result_end));
     movq(scratch, new_space_allocation_top);
     movq(result, Operand(scratch, 0));
   } else if (result.is(rax)) {
     load_rax(new_space_allocation_top);
   } else {
     movq(kScratchRegister, new_space_allocation_top);
     movq(result, Operand(kScratchRegister, 0));
   }
 }
 
@@ skipping 40 matching lines @@
       if (scratch.is_valid()) {
         movl(scratch, Immediate(0x7291));
       }
     }
     jmp(gc_required);
     return;
   }
   ASSERT(!result.is(result_end));
 
   // Load address of new object into result.
-  LoadAllocationTopHelper(result, result_end, scratch, flags);
+  LoadAllocationTopHelper(result, scratch, flags);
 
   // Calculate new top and bail out if new space is exhausted.
   ExternalReference new_space_allocation_limit =
       ExternalReference::new_space_allocation_limit_address();
 
   Register top_reg = result_end.is_valid() ? result_end : result;
 
   if (top_reg.is(result)) {
     addq(top_reg, Immediate(object_size));
   } else {
@@ skipping 36 matching lines @@
         movl(scratch, Immediate(0x7291));
       }
       // Register element_count is not modified by the function.
     }
     jmp(gc_required);
     return;
   }
   ASSERT(!result.is(result_end));
 
   // Load address of new object into result.
-  LoadAllocationTopHelper(result, result_end, scratch, flags);
+  LoadAllocationTopHelper(result, scratch, flags);
 
   // Calculate new top and bail out if new space is exhausted.
   ExternalReference new_space_allocation_limit =
       ExternalReference::new_space_allocation_limit_address();
   lea(result_end, Operand(result, element_count, element_size, header_size));
   movq(kScratchRegister, new_space_allocation_limit);
   cmpq(result_end, Operand(kScratchRegister, 0));
   j(above, gc_required);
 
   // Update allocation top.
@@ skipping 21 matching lines @@
         movl(scratch, Immediate(0x7291));
       }
       // object_size is left unchanged by this function.
     }
     jmp(gc_required);
     return;
   }
   ASSERT(!result.is(result_end));
 
   // Load address of new object into result.
-  LoadAllocationTopHelper(result, result_end, scratch, flags);
+  LoadAllocationTopHelper(result, scratch, flags);
 
   // Calculate new top and bail out if new space is exhausted.
   ExternalReference new_space_allocation_limit =
       ExternalReference::new_space_allocation_limit_address();
   if (!object_size.is(result_end)) {
     movq(result_end, object_size);
   }
   addq(result_end, result);
   movq(kScratchRegister, new_space_allocation_limit);
   cmpq(result_end, Operand(kScratchRegister, 0));
@@ skipping 244 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64