[PATCH] Add a shrink-wrapping pass to improve the placement of prologue and epilogue.
kristof.beyls at arm.com
Thu Apr 23 10:47:46 PDT 2015
> -----Original Message-----
> From: Quentin Colombet [mailto:qcolombet at apple.com]
> Sent: 23 April 2015 17:52
> To: qcolombet at apple.com; grosbach at apple.com
> Cc: kparzysz at codeaurora.org; Kristof Beyls; dberlin at dberlin.org; Amara
> Emerson; justin.holewinski at gmail.com; llvm-commits at cs.uiuc.edu
> Subject: Re: [PATCH] Add a shrink-wrapping pass to improve the placement
> of prologue and epilogue.
> Hi Kristof,
> Thanks for your feedbacks.
> > Overall, I guess that this needs support in at least one backend, so
> regression tests can be added before this is in a state ready to commit?
> Whatever people prefers. I have a patch to add the support for shrink-
> wrapping for AArch64, I can just merge it with this one with the path
> disabled by default.
I guess I'm missing something obvious. I'm assuming that for the functions
where the shrink-wrapping optimization triggers, it's always, or almost always
a win? I am assuming that the effect of the patch as shown, when triggering,
moves a single prologue and a single epilogue sequence from a path that's
executed once per function call to a path that's executed at most once per
If that assumption were true, there would be no reason to disable this pass
by default, right? So, how is my assumption incorrect?
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