An question about default opened option "-fstack-protector-strong"

[Shao, Ting]

Hi,

I was trying to enable the "stack smashing protection" for node.js(issue 20928<https://github.com/nodejs/node/issues/20928>). And I switched it on using "-fstack-protector"
And made a benchmark test, while the result is quite strange. Then I found on my Ubuntu 16.04, the -fstack-protector-strong
Was by default enabled. I checked it using the command:

Gcc -Q -v main.c

And found the -fstack-protector-strong flag was listed inside the "options passed" by default.

So based on these, I have some questions:
1.      I installed gcc from apt-get by default, is Ubuntu providing a customized version of GCC?
2.      If answer of 1 is yes, then you may have a repo that host the customized GCC code, if I am right, could you please show me where I can find the proof of that customization?
      That would be much appreciated. :) Or if you can't find the right code, can you show me where I can find the repo, then I can traverse the code and history to find the proof myself.

Below is my env:
Ubuntu 16.04
Gcc: 5.4.0-6ubuntu1~16.04.9
CPU: Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz x86_64

Thanks with regards,
Shaoting

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