[PATCH] [RegisterScavenger] Fix handling of predicated instructions

Tobias Edler von Koch tobias at codeaurora.org
Wed Apr 22 13:37:43 PDT 2015


On Tue, 21 Apr 2015 14:18:56 -0700 Quentin Colombet
<qcolombet at apple.com> wrote:
> > On Apr 21, 2015, at 1:35 PM, Evan Cheng <evan.cheng at apple.com> wrote:
> > 
> > + Quentin
> > 
> > Quentin, what do you think? More specifically, is it true that kill flags are always in place on predicated instructions?
> I haven’t checked the if-converstion pass, but I am not sure those flags are updated correctly with predicated instructions.
> Tobias, which commit makes you think the problem has been solved?

I don't know of a specific commit. But here's my reasoning:

If kill flags were incorrectly set on predicate instructions, wouldn't
we see uses of those registers after they were killed? The
MachineVerifier would flag these up.

The opposite case, a kill flag not being set when it really should be,
is still fine - the patch shouldn't affect that situation.


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