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Gmane
From: Chris Lattner <clattner <at> apple.com>
Subject: Re: RFC: liveoncall parameter attribute
Newsgroups: gmane.comp.compilers.llvm.devel
Date: Thursday 4th June 2015 18:00:05 UTC (over 2 years ago)
> On Jun 1, 2015, at 4:28 PM, Philip Reames 
wrote:
> 
> An alternate approach would be to insert a dummy use into the callee,
lower it to a noop late in the backend, and teach the inliner to remove it
after inlining.  I suspect this would be both harder to implement and
harder to optimize around.


Hi Philip,

Without knowing more, using an intrinsic for this seems like a better way
to go: the intrinsic call will keep value alive, and you can special case
the behavior for inlining in the inliner, which is apparently the only
place where this is problematic.  I suspect that this will be a lot less
impact on the existing compiler, be much less likely to break going
forward, and also trivially composes across other existing argument
attributes.

What are the disadvantages of going with a new intrinsic?

-Chris
 
CD: 4ms