[Patch] [AArch64] Fix registerAllocator assigns same register for base and wback in pre/post-index load and store

[Quentin Colombet]

Hi Steven,

Could you add a few test cases? (Ideally one per instruction you are patching.)

Thanks,
-Quentin

On Aug 8, 2014, at 5:15 PM, Steven Wu <stevenwu at apple.com> wrote:

> Hi
> 
> This patch fix a bug that sometimes register allocator may assign same register as base and writeback register in pre/post-index loads and stores for AArch64.
> According to ARMv8 manual, such result will have uncertain behaviors and clang as will reject them as well. Adding earlyclobber constraints to avoid them.
> Since this behavior will depend on the register allocator so I am not sure how to produce a test. I can provide a testcase if anyone want to reproduce the problem.
> 
> Patch attached. Please review and commit it for me.
> 
> Thanks
> 
> Steven
> <postindex.patch>
> 
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