[FFmpeg-devel] [PATCH] swresample/arm: avoid conditional branch to PLT in THUMB-2.

Michael Niedermayer michael at niedermayer.cc
Thu Apr 19 01:46:07 EEST 2018

On Tue, Apr 17, 2018 at 12:36:45PM -0700, Rahul Chaudhry wrote:
> On Tue, Apr 17, 2018 at 6:17 AM, Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> > why does it go through the PLT at all ?
> You're right. The branches don't have to go through the PLT at all.
> Here's an alternate patch that modifies the branches to skip the PLT
> and jump directly to the targets.
> Note that unlike the previous patch, this patch changes semantics.
> When branches were going through PLT, the targets could be overridden
> at runtime by another shared library or the main executable. With
> this patch, they can no longer be overridden. The branches will always
> go to the corresponding functions defined in this assembly file.

please make sure this works on apple based arm (unless you know it works)
(ive tested qemu linux based)

Also please add a commit message


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.
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