[PATCH] D28785: Split exception.cpp and new.cpp implementation into different files for different runtimes

[Shoaib Meenai via Phabricator via cfe-commits]

smeenai added a comment.

I really like the cleanup, but I'm not the biggest fan of taking more Microsoft dependencies than necessary. I don't see any way around `operator new`/`operator delete` (since replacement in COFF can only work with a static library with one function per object file, the way `msvcrt.lib` does it, and it doesn't seem to be worth the trouble to provide our own corresponding static library), but I think the rest are avoidable (though it's entirely possible I'm missing something, of course).



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Comment at: include/exception:85
 
+#if defined(_LIBCPP_ABI_MICROSOFT)
+#include <vcruntime_exception.h>
----------------
What's the rationale for relying on Microsoft's exception implementation rather than libc++'s?


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Comment at: include/new:96
+#if defined(_LIBCPP_ABI_MICROSOFT)
+#include <new.h>
+#endif
----------------
`new.h` will pull in `new` unless you define certain macros. Is that desirable?


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Comment at: include/new:138
 
+typedef void (*new_handler)();
+_LIBCPP_FUNC_VIS new_handler set_new_handler(new_handler) _NOEXCEPT;
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Again, why defer these to Microsoft's STL? In particular, `set_new_handler` and `get_new_handler` seem to be part of `msvcprt`, which means we would take a runtime dependency on Microsoft's C++ library, which doesn't seem great.

These functions should map pretty well to `_query_new_handler` and `_set_new_handler` (apart from the different function pointer signature, which can be thunked around), right?


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Comment at: include/new:177
 
+#if !defined(_LIBCPP_ABI_MICROSOFT)
+
----------------
Might be helpful to have a comment explaining why we wanna defer these to msvcrt on Windows?

Also, VS 2015 doesn't seem to have the sized and aligned allocation and deallocation functions. I haven't checked 2017.


https://reviews.llvm.org/D28785