[LLVMdev] Path profiling command

Linh Ho Tran hotranlinh at yahoo.com
Tue May 10 21:47:13 PDT 2011


Hi All,

I use llvm version 2.9. llvm-prof does not support to read path profiling info. 
So could I use any way else to read path profiling info?

Thanks

Linh


________________________________
From: Andreas Neustifter <andreas.neustifter at gmail.com>
To: Andrew Trick <atrick at apple.com>
Cc: Linh Ho Tran <hotranlinh at yahoo.com>; "llvmdev at cs.uiuc.edu Mailing List" 
<llvmdev at cs.uiuc.edu>; Bob Wilson <bob.wilson at apple.com>; Adam Preuss 
<apreuss at ualberta.ca>; Jeff Kunkel <jdkunk3 at gmail.com>; J Nelson Amaral 
<amaral at cs.ualberta.ca>
Sent: Tue, May 10, 2011 3:44:46 PM
Subject: Re: [LLVMdev] Path profiling command

Hi All!

I was involved in the LLVM profiling business during late 2009 and
early 2010 but I was not working on the path profiling but the
"regular" profiling code. So I'm only guessing in case there is not
other answer.

On 9 May 2011 20:19, Andrew Trick <atrick at apple.com> wrote:
>
> On May 9, 2011, at 3:36 AM, Linh Ho Tran wrote:
>
> [...]
>
> The error message from llvm-prof is:  llvm-prof: Unkknown packet #5
>
> Could you explain me the error message?
>
> Are there errors in the command chain?
>
> What is the format of file  llvmprof.out? Is it possible to read
> llvmprof.out from command llvm-prof by ignoring step 5?
>
> What is the purpose of command in step 5?

Most of the LLVM profiling uses a binary format to dump the data, this
dump consists of several blocks with block headers, those headers
define the content of the block. To me it seem (again speculating
here) that there is a block header in this dump that is not recognised
by llvm-prof.

Ensure that the version of llvm-prof is from the same build as the
version of opt that you are using to instrument the code. If those
versions match then code is most likely broken.

Cheers, Andi
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