Not being able to keep tables out of compilation

[tvarela7]

I'm migrating from older version of CMSIS-DSP, since I need some of the new functions (i.e. arm_atan2_f32, arm_rfft_fast_f32). Given my current framework, I decided to build libCMSISDSP.a with Makefile, using GCC 11.2 and different flags such as -mcpu=cortex-m7 -mfpu=fpv5-d16 -Ofast -ffast-math -mfloat-abi=hard.

I then included it in my main repo, basically replacing the old .a CMSIS-DSP library and include files. I also replaced all fft init functions for the recommended ones (i.e. arm_cfft_init now is arm_cfft_init_512_f32), as mentioned in readme file to avoid all tables from being included. I'm also using flags such as -ffunction-sections and -fdata-sections in my final build, for optimization. I've seen that in the past this would be tackled using defines such as ARM_DSP_CONFIG_TABLES, but not with the last version.

Moreover, I did not used arm_math.h but rather individually added the needed includes. i.e.:

#include "transform_functions.h"
#include "complex_math_functions.h"
#include "fast_math_functions.h"

However, it seems nothing is stopping the final build of overflowing flash memory (like 1mb of unwanted code). I've checked in .map file and all tables are there, even those that I shouldn't be using.

Any ideas of what I might be missing here? maybe some other step other than replacing fft init functions?

Thanks!

[christophe0606]

@tvarela7 There may be some options to use at link. For GCC you need to use --gc-sections for linking.

[CookiePLMonster]

Any particular reason those tables cannot be declared static? This explicitly incentivizes the linker to skip them if not referenced.

[tvarela7]

@christophe0606 thanks for answering. It's solved now. I was actually already using that flag, but I did a silly mistake messing up the Makefiles from CMSIS vs my own project, and I thought I was adding -fdata-sections -ffunction-sections but I was actually just using them in my code...

Now I added -fdata-sections -ffunction-sections when compiling CMSIS library and everything seems to be working as expected.

Thanks again!

[christophe0606]

I am glad to know !