[PATCH] D19483: docs: Update SafeStack docs with separate-stack-seg feature and various USP storage modes

[Michael LeMay via cfe-commits]

mlemay-intel added a comment.

In http://reviews.llvm.org/D19483#417857, @pcc wrote:

> You should be using `-target x86-unknown-contiki` or similar. That should tune the behaviour to what is required for that OS. See what we have in `TargetLoweringBase::getSafeStackPointerLocation` to provide Android-specific behaviour for example.


This makes sense for the example I gave.  However, there are also more complicated situations.  Sometimes it is necessary to specify different options for different files that are compiled for the same OS.  For example, early during the initialization of a dynamic linker or C library, a single-threaded mode of USP storage needs to be supported.  TLS is not available at that time.  How should requirements like that be conveyed to the compiler?

> The existence of flags is not justification to add more. Besides, it appears that the `-safe-stack-usp-storage` flag was added without proper review. It was reviewed in http://reviews.llvm.org/D15673, but the mailing list was not added as a subscriber. If I had been aware of that review I would have made the same objections at that time.


Sorry, I only recently learned that the mailing list should be added as a subscriber.  Prior to that, I thought that patches were automatically sent to the appropriate mailing lists.


http://reviews.llvm.org/D19483