New Post: Code size #1 #10
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| So in this program we have: | ||
| * 10800 bytes of `text`, which is code | ||
| * 104 bytes of `data`, which is statically initalized memory | ||
| * 8272 bytes of `bcc`, which is zero-initialized memory |
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| ### Measuring overall code size | ||
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| The simplest way to measure code size is to inspect the different sections of |
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-Wl,--print-memory-usage is pretty cool too. Suffers the fate of data being lumped into ram count but at link you get something like:
Memory region Used Size Region Size %age Used
rom: 10800 B 256 KB 4.12%
ram: 8376 B 32 KB 25.56%
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Added a note, though this is an inferior solution to size because you cannot compute your actual ROM usage from this output, since it does not break out data vs. bss
| To avoid confusion, I prefer to use a small script to compute the sizes: | ||
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| ```bash | ||
| #!/bin/bash |
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MAYBE: Might be neat to publish a python package that does this type of thing.
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This would be ~1 day of work
| 00000430 00000692 t _usart_set_config | ||
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| Here we see that our largest symbol is `_usart_set_config` which is takes 692 |
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is takes -> takes up or uses ?
| do: | ||
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| ```terminal | ||
| francois-mba:with-libc francois$ arm-none-eabi-nm --print-size --size-sort --radix=d build/with-libc.elf | tail -30 |
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MAYBE: -l is nice to tack on too for line info
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Added a note, but didn't copy the output as it gets quite messy.
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| Now open your favorite web browser at localhost:5000, and enjoy! | ||
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| Note: You may notice that some code size will be attributed to symbols under |
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Specifically the newlib bundled with gcc doesn't build with -g fwiw :(
| information. As such, you'll need to make sure you've got the following CFLAGS | ||
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| * `-g`: this generates debug information which puncover requires for analysis |
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puncover doesn't need it but you get some extra goodies (like macro definitions) in elf when you use -g3 (default level is 2)
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Not going to add that here
Add the first post in the "code size" series. This first post focuses on measuring code size, before optimizing.