determining code size

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geoffrey.brown
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determining code size

Postby geoffrey.brown » Fri Sep 04, 2020 1:35 pm

The standard build optimizes code size by compiling functions into separate sections and then keeping only those parts of the binary that are actually used. This works great but I have a small technical problem -- is there a convenient way to to determine the contribution to code size of various modules ?

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Giovanni
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Re: determining code size

Postby Giovanni » Fri Sep 04, 2020 3:58 pm

You could make a customized linker script that loads modules into separate sections, at least the module you are measuring, I think it is possible. You should also disable GC, LTO and functions alignment for the estimation to make sense.

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Re: determining code size

Postby psyco » Fri Sep 04, 2020 11:48 pm

My go-to for function and global variable sizes is:

Code: Select all

arm-none-eabi-nm --print-size --size-sort build/ch.elf


If you use C++, add a -C for demangling. By default, the second column is size.

If your modules have a prefix to all functions, it should just be a bit of post-processing to get the numbers. Do note LTO can screw around with things (mainly combining functions).


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