[PATCH] D27052: [compiler-rt][asan] Fix overlaping parameters for memmove/memcpy on windows.

[Reid Kleckner via llvm-commits]

rnk added inline comments.


================
Comment at: lib/asan/asan_interceptors.cc:427
+  ASAN_MEMMOVE_IMPL(nullptr, to, from, size);
+#endif
+}
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filcab wrote:
> I have a problem with this. It seems like it's hiding problems.
> 
> If the runtime called `__asan_memcpy`, it is because we actually had a call to `memcpy`, so we should check for overlap properly. This code is turning that off.
> If `memcpy` and `memmove` are defined to the same, we shouldn't be erroring when `memmove` is called, though. But I don't see how calls to `__asan_memcpy`/`__asan_memmove` get converted to be the same function, since that's an ASan function, not the libc one.
In practice, we found, as Apple did, that on platforms where memcpy aliases memmove, it is not feasible to intercept them separately. If you trace through the existing logic, you'll see that we're already suppressing this error in the same way on Mac.


https://reviews.llvm.org/D27052