[PATCH] D37262: The issues with X86 prefixes: step 2

[Andrew V. Tischenko via Phabricator via llvm-commits]

avt77 added inline comments.


================
Comment at: lib/Target/X86/AsmParser/X86AsmParser.cpp:2866
+  if (static_cast<X86Operand &>(*Operands.back()).Kind == X86Operand::Prefix) {
+    X86Operand &Prefix = static_cast<X86Operand &>(*Operands.pop_back_val());
+    Prefixes = Prefix.getPrefix();
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craig.topper wrote:
> I'm not sure this isn't a use after free. pop_back_val is going to return a std::unique_ptr which you dereferenced, but I'm not convinced anything is keeping the std::unique_ptr alive.
It seems that everything is OK here because

  C++  Utilities library  Dynamic memory management std::unique_ptr 

typename std::add_lvalue_reference<T>::type operator*() const;  (1)	(since C++11)
pointer operator->() const noexcept;                                             (2)	(since C++11)

operator* and operator-> provide access to the object owned by *this.
The behavior is undefined if get() == nullptr

Parameters
(none)

Return value
1) Returns the object owned by *this, equivalent to *get().
2) Returns a pointer to the object owned by *this, i.e. get().

Am I right?


https://reviews.llvm.org/D37262