llvm dev - Oct 2017 - question about mem2reg

Hello,


I just upgraded my llvm to 5.0.0. I applied mem2reg pass as follows:


opt -mem2reg m2rtttl.bc > m2rtttl.opt


But after that, I compared m2rtttl.bc and m2rtttl.opt. I noticed that there are
no difference between m2rtttl.bc and m2rtttl.opt. Did I apply llvm in the
correct way?


Thanks a lot for the help!


Best,


                           Linhai
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Hello Linhai,

When compiled with -O0, clang 5.0 started to add optnone attribute to each
function, which prevents further optimizations afterwards including mem2reg
pass. To prevent that, add "-Xclang -disable-O0-optnone" to clang
command
line arguments.

Thank you,
Heejin

On Sat, Oct 14, 2017 at 8:59 PM Linhai Song via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hello,
>
>
> I just upgraded my llvm to 5.0.0. I applied mem2reg pass as follows:
>
>
> opt -mem2reg m2rtttl.bc > m2rtttl.opt
>
>
> But after that, I compared m2rtttl.bc and m2rtttl.opt. I noticed that
> there are no difference between m2rtttl.bc and m2rtttl.opt. Did I apply
> llvm in the correct way?
>
>
> Thanks a lot for the help!
>
>
> Best,
>
>
>                            Linhai
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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Thanks a lot!


This solved my problem.


Best,


               Linhai

________________________________
From: Heejin Ahn <aheejin at gmail.com>
Sent: Sunday, October 15, 2017 5:22:38 AM
To: Linhai Song; llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] question about mem2reg

Hello Linhai,

When compiled with -O0, clang 5.0 started to add optnone attribute to each
function, which prevents further optimizations afterwards including mem2reg
pass. To prevent that, add "-Xclang -disable-O0-optnone" to clang
command line arguments.

Thank you,
Heejin

On Sat, Oct 14, 2017 at 8:59 PM Linhai Song via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:

Hello,


I just upgraded my llvm to 5.0.0. I applied mem2reg pass as follows:


opt -mem2reg m2rtttl.bc > m2rtttl.opt


But after that, I compared m2rtttl.bc and m2rtttl.opt. I noticed that there are
no difference between m2rtttl.bc and m2rtttl.opt. Did I apply llvm in the
correct way?


Thanks a lot for the help!


Best,


                           Linhai

_______________________________________________
LLVM Developers mailing list
llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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