Godbolt viewer

[Sudakshina Dutta]

Dear all,

Greetings from India. Please go to the link https://godbolt.org/z/z375aK4KK where the LLVM Opt pipeline viewer is shown. I am unable to find the output shown in the windows. Some passes are listed in a window against which two vertical windows are displayed. As the passes change, the outputs of the windows change.  Can you kindly help me in understanding the output shown in the marked windows of the attached file ?

Thanks,

Sudakshina

[Matt Godbolt]

Hi Sudakshina!

Thanks for the email!  I'm not an expert in how the LLVM opt system works, but: As I understand it:

• You pick the single function whose opt output you want to look at in the top Function: drop down
• You can look at the individual passes whose output affected the LLVM internal representation on the left of the three panes in the pipeline viewer, for example you might select "TailCallElemPass". Passes that made no changes are not shown.
• The two other panes show a difference view: the lefthand is the "what was the code before this optimization pass was applied", and the right-hand "what was the code after". Red lines show deletions/modifications and green lines are added/modified (these are the two areas you highlighted on your screenshot).

In the screenshot you attached it's hard to see the additions/removals in the two areas you ticks as the window size is a little small; but here's an example of seeing the "TailCallElemPass" on cross4(double) [ https://godbolt.org/z/qrxdooYGc - I moved some windows around a bit ]

Hope that helps!

--matt

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[Sudakshina Dutta]

Thank you Matt. It answered my question.

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[Matt Godbolt]

Awesome! Glad to hear it :)

--matt

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