hans added a comment.

In https://reviews.llvm.org/D43108#1005904, @nruslan wrote:

> @hans: One real-world example is when it is used to compile UEFI code using 
> PE/COFF targets natively. Obviously, UEFI uses ABI which is basically almost 
> the same as MS ABI, except that chkstk is not used. It mostly works (I 
> actually was able to get it running) except the cases when the code contains 
> variable-sized arrays allocated on stacks. Unfortunately, stack-probe-size 
> will only help with fixed sized array but will not help to solve the problem 
> described in the bug description since stack usage is unknown at compile 
> time. MinGW does not have this problem because it provides this flag.

I see, interesting. Might be worth mentioning in the commit message for others 
wondering what the flag is useful for.

> @MatzeB : there is a test on LLVM side (related review). Do you think the 
> test is needed for clang side? If so, please let me know, what kind of test 
> it is supposed to be.

Yes please, I think think there should be on in test/Driver/ to check that 
forwarding the flag to cc1 (and if we have a -mno-foo, there should maybe be a 
-mfoo variant too?), and a test in test/CodeGen/ to check that the attribute 
gets put on the functions correctly. Perhaps r321992 is a good example to look 

  rC Clang


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