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Re: Question about DRAP register and reserving hard registers


On Mon, 2015-06-29 at 11:10 +0100, Richard Henderson wrote:

> > OK, I think I have this part of the code working on MIPS but
> > crtl->drap_reg is used in the epilogue as well as the prologue even if
> > it is not 'live' in between.  If I understand the code correctly the x86
> > prologue pushes the drap register on to the stack so that the epilogue
> > can pop it off and use it to restore the stack pointer.  Is my
> > understanding correct?
> 
> Yes.  Although that saved copy is also used by unwind info.

Do you know how and where this saved copy is used by the unwind info?
I don't see any indication that the unwind library knows if a stack has
been dynamically realigned and I don't see where unwind makes use of
this value.

Steve Ellcey
sellcey@imgtec.com


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