[PATCH] LivePhysRegs: Add support to add pristine registers when populating with live-in/live-out registers.

Matthias Braun matze at braunis.de
Fri May 29 16:06:37 PDT 2015

In http://reviews.llvm.org/D10139#181352, @MatzeB wrote:

> In http://reviews.llvm.org/D10139#181314, @qcolombet wrote:
> > Hi Matthias,
> >
> > I miss something.
> >  Why do we need to account for the pristine registers?
> Before prologue/epilogue insertion we don't need to account for them. All current users for LivePhysRegs are before prologue/epilogue insertion so they won't need this (by default AddPristineRegs is false).

Actually I just realized that the StackMapLiveness pass uses LivePhysRegs after prologue/epilogue insertion; At a first glance I'd say this is a bug and will miss the pristine registers (though I'm not sure what the repercussions are if pristine regs are missed in patchpoint instruction (or maybe someone adjust for that somewhere else in the code).




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