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Date: Fri, 05 Oct 2012 22:50:00 -0000
From: Jason Merrill <jason@redhat.com>
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To: Sriraman Tallam <tmsriram@google.com>
CC: Xinliang David Li <davidxl@google.com>, mark@codesourcery.com,        nathan@codesourcery.com, "H.J. Lu" <hjl.tools@gmail.com>,        Richard Guenther <richard.guenther@gmail.com>,        Jan Hubicka <jh@suse.cz>, Uros Bizjak <ubizjak@gmail.com>,        reply@codereview.appspotmail.com,        GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: User directed Function Multiversioning via Function Overloading (issue5752064)
References: <20120307004630.A503DB21B6@azwildcat.mtv.corp.google.com> <CAMe9rOrdZaTDzakgpHxXWE3hhUvR7LNO1NkUrtAJJCjTjz_mjg@mail.gmail.com> <CAAs8Hmzw=tTGLypq1GQ7cA=DFupP8VpwB5QiE+jwLcYOovV=YQ@mail.gmail.com> <CAAs8HmzF0JJWPvFzoNGMSJ7ZS1h4KmROdx29-__8Oh9yUA1=JA@mail.gmail.com> <CAAs8HmxgMMVtCd9Xc4x_wJS80YCDrVFVRWsF3-G9uYjyE0OR6w@mail.gmail.com> <4FF7D1C6.90407@redhat.com> <CAAkRFZ+=y=nOAhAx9f5teUORsfAuVAYFuWCt4qf56DHZFo2uJw@mail.gmail.com> <4FF96D0C.5060406@redhat.com> <CAAkRFZKxLsJLr1Z23s8W=GTX+Or5=Cz2kTD9ySKJdjrRT8WGQQ@mail.gmail.com> <4FFBF9F5.6020306@redhat.com> <CAAkRFZKdC-zM-U3njRziRrP4O5Dc=-wt70Q2Kt-Y5ErrgL4GLg@mail.gmail.com> <CAAs8HmxHF38ktt6syjWp-MpjiX+6NcXh7_8Xn6iKnAiF2vRymQ@mail.gmail.com> <5008708E.1030109@redhat.com> <CAAs8Hmy7h5SGkJ+D5v_DnXs-h4B2d_YWEcstufb5=SowbVBp0Q@mail.gmail.com> <CAAs8HmyKPG_LxxxP2ngkGTFAKUPXQDJsbbsrOB_oAP0ViyER3g@mail.gmail.com> <506F1C5D.9060500@redhat.com> <CAAs8HmxSO4eP=g+dQRxXvcWijEUE0ZFAvmBYZ27UByd0HWtcQg@mail.gmail.com>
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On 10/05/2012 05:57 PM, Sriraman Tallam wrote:
> In general, the dispatcher is always necessary since it is not known
> what function version will be called at compile time. This is true
> whether it is a direct or an indirect call.

So you want to compile with lowest common denominator flags and then 
choose a faster version at runtime based on the running configuration? 
I see.

Jason