llvm dev - Jan 2019 - [X-ray] How to check successful instrumentation and generate call trace?

Hi all,


I want to test X-ray performance and compare it with other research tools, so I
use Clang 7.0.0 to compile and instrument GNU binutils-2.3.1 with the following
commands:


cd binutils-2.31/
 mkdir build
cd build/
CC=$local/clang CXX=$local/clang++ CFLAGS=-fxray-instrument
CXXFLAGS=-fxray-instrument ../configure --prefix=/home/zhangysh1995/local
make


Then I extract instrumentation map with llvm-xray extract addr2line and it
returns:
---
- { id: 1, address: 0x000000000041CD70, function: 0x000000000041CD70, kind:
function-enter, always-instrument: false, function-name: '' }
- { id: 1, address: 0x000000000041D026, function: 0x000000000041CD70, kind:
function-exit, always-instrument: false, function-name: '' }
- { id: 2, address: 0x000000000041D4F0, function: 0x000000000041D4F0, kind:
function-enter, always-instrument: false, function-name: '' }
- { id: 2, address: 0x000000000041DAFA, function: 0x000000000041D4F0, kind:
function-exit, always-instrument: false, function-name: '' }
- { id: 3, address: 0x000000000041E570, function: 0x000000000041E570, kind:
function-enter, always-in
......
......



Does the map mean that no function is instrumented? Should I change my commands?
BTW, after instrumentation could I run the binary and get trace directly?


Here is the link to current documentation: https://llvm.org/docs/XRay.html


Thank you all,
Yushan
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> On 21 Jan 2019, at 16:16, 张雨姗(ZHANG Yushan)-11310380 via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> 
> Hi all,
> 
> I want to test X-ray performance and compare it with other research tools,
so I use Clang 7.0.0 to compile and instrument GNU binutils-2.3.1 with the
following commands:
> 
> cd binutils-2.31/
> mkdir build
> cd build/
> CC=$local/clang CXX=$local/clang++ CFLAGS=-fxray-instrument
CXXFLAGS=-fxray-instrument ../configure --prefix=/home/zhangysh1995/local
> make
> 
> Then I extract instrumentation map with llvm-xray extract addr2line and it
returns:
> ---
> - { id: 1, address: 0x000000000041CD70, function: 0x000000000041CD70, kind:
function-enter, always-instrument: false, function-name: '' }
> - { id: 1, address: 0x000000000041D026, function: 0x000000000041CD70, kind:
function-exit, always-instrument: false, function-name: '' }
> - { id: 2, address: 0x000000000041D4F0, function: 0x000000000041D4F0, kind:
function-enter, always-instrument: false, function-name: '' }
> - { id: 2, address: 0x000000000041DAFA, function: 0x000000000041D4F0, kind:
function-exit, always-instrument: false, function-name: '' }
> - { id: 3, address: 0x000000000041E570, function: 0x000000000041E570, kind:
function-enter, always-in
> ......
> ......
> 
> Does the map mean that no function is instrumented? Should I change my
commands?
This means that the generated binary already has the instrumentation map. It
looks like you also already have the function addresses, which if the binary is
not stripped of symbols must have the function names. If you add the
`-symbolize` flag to the invocation of `llvm-xray extract` then that should get
the function names.
> BTW, after instrumentation could I run the binary and get trace directly?
You should be able to enable tracing of instrumented binaries using an
environment variables.
> 
> Here is the link to current documentation: https://llvm.org/docs/XRay.html
> 
In that documentation, it shows the table of options you can set in the
XRAY_OPTIONS environment variable:

http://llvm.org/docs/XRay.html#xray-runtime-library

In the example at:

http://llvm.org/docs/XRayExample.html

You can set:

XRAY_OPTIONS="patch_premain=true:xray_mode=xray-basic:verbosity=1”

To get traces.

Cheers

-- Dean

Hi Dean,




Thanks for your last reply. 



I compiled "tmux" with `CC=clang CXX=clang++
CXXFLAGS=-fxray-instrument CFLAGS=-fxray-instrument`, and it succeeded.


I installed the binary with `make install` to a local folder, and run it with
XRAY_OPTIONS="patch_premain=true:xray_mode=xray-basic:verbosity=1"
tmux'.



But after it exited normally, I have no trace generated or any error. And I also
used `llvm extract -symbolize` to make sure the binary is instrumented.



What is the cause for it? Does it depend on functions called during the
execution?



What environment variables I should use to guarantee there is always a trace
log?




Thank you,
Yushan




 
------------------ Original ------------------
From:  "Dean Michael Berris"<dean.berris at gmail.com>;
Date:  Mon, Jan 21, 2019 01:26 PM
To:  ""张雨姗(ZHANG Yushan)-11310380""<zhangys3 at
mail.sustc.edu.cn>;
Cc:  "llvm-dev"<llvm-dev at lists.llvm.org>; 
Subject:  Re: [llvm-dev] [X-ray] How to check successful instrumentation and
generate call trace?

 

> On 21 Jan 2019, at 16:16, 张雨姗(ZHANG Yushan)-11310380 via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> 
> Hi all,
> 
> I want to test X-ray performance and compare it with other research tools,
so I use Clang 7.0.0 to compile and instrument GNU binutils-2.3.1 with the
following commands:
> 
> cd binutils-2.31/
> mkdir build
> cd build/
> CC=$local/clang CXX=$local/clang++ CFLAGS=-fxray-instrument
CXXFLAGS=-fxray-instrument ../configure --prefix=/home/zhangysh1995/local
> make
> 
> Then I extract instrumentation map with llvm-xray extract addr2line and it
returns:
> ---
> - { id: 1, address: 0x000000000041CD70, function: 0x000000000041CD70, kind:
function-enter, always-instrument: false, function-name: '' }
> - { id: 1, address: 0x000000000041D026, function: 0x000000000041CD70, kind:
function-exit, always-instrument: false, function-name: '' }
> - { id: 2, address: 0x000000000041D4F0, function: 0x000000000041D4F0, kind:
function-enter, always-instrument: false, function-name: '' }
> - { id: 2, address: 0x000000000041DAFA, function: 0x000000000041D4F0, kind:
function-exit, always-instrument: false, function-name: '' }
> - { id: 3, address: 0x000000000041E570, function: 0x000000000041E570, kind:
function-enter, always-in
> ......
> ......
> 
> Does the map mean that no function is instrumented? Should I change my
commands?
This means that the generated binary already has the instrumentation map. It
looks like you also already have the function addresses, which if the binary is
not stripped of symbols must have the function names. If you add the
`-symbolize` flag to the invocation of `llvm-xray extract` then that should get
the function names.
> BTW, after instrumentation could I run the binary and get trace directly?
You should be able to enable tracing of instrumented binaries using an
environment variables.
> 
> Here is the link to current documentation: https://llvm.org/docs/XRay.html
> 
In that documentation, it shows the table of options you can set in the
XRAY_OPTIONS environment variable:

http://llvm.org/docs/XRay.html#xray-runtime-library

In the example at:

http://llvm.org/docs/XRayExample.html

You can set:

XRAY_OPTIONS="patch_premain=true:xray_mode=xray-basic:verbosity=1”

To get traces.

Cheers

-- Dean
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