[PATCH] D22292: [libunwind] Fix unw_getcontext for ARMv6-m

Weiming Zhao via cfe-commits cfe-commits at lists.llvm.org
Wed Jul 13 10:04:32 PDT 2016

weimingz added a comment.

In http://reviews.llvm.org/D22292#482750, @rmaprath wrote:

> In http://reviews.llvm.org/D22292#482560, @compnerd wrote:
> > Can you explain why the write back is needed?  You are doing the write back on r0, but then adjusting it back.  So it is unclear why this change is needed.  Could you provide some more context.  A test case would be even better.
> This is because `STM` without write-back is only defined in Thumb-2 (Thumb-1 version must always have write-back set).
> Now, I scanned through our downstream sources and realized we have some local patches in this area that addresses this (in a bit more general way - and possibly some other fixes).
> @weimingz: If you can hold off for a bit, I can put these patches for review and sort these out for good (need to clean up the patches first). If you want to get this fixed asap, you should add a check for `__ARM_ARCH_ISA_THUMB == 1` in addition to `!defined(__ARM_ARCH_ISA_ARM)`.

Cool. We can hold off. Please upload the patches.


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