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Compiling libgcc not optimized

Good moorning,

I am trying to compile libgcc for arm-none-eabi target from scratch, since I need to compare Floating Point SW emulation on an ARM Cortex-M4 and Risc-V based processors. The problem is that by default GCC includes the optimized version of FP SW emulation functions which is ieee754-sf.S.

Does anyone knows how to exclude ieee754-sf.S in the libgcc compilation process? In particular how to configure GCC?

Thanks,

Top replies

a.surati over 4 years ago +1

IANAE, but below is a hack one can try. No warranty of any kind. The asm sources for the optimized routines are collected inside the LIB1ASMFUNCS make variable. gccsrc/libgcc/Makefile.in has libgcc...

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0 a.surati over 4 years ago in reply to EnricoTabanelli

Okay. Those steps replaced the optimized code with the unoptimized one, afaics within the libgcc.a built.

Additionally, libgcc.a and gcc compiler redefine __addsf3 to __aeabi_fadd. Such redefinitions are applied to other functions too.

For the sake of testing a single function __addsf3, these additional changes (on top of earlier ones) were made:

gccsrc/gcc/config/arm/arm.c has:
...
set_optab_libfunc (add_optab, SFmode, "__aeabi_fadd");
...

Comment that line.

gccsrc/libgcc/config/arm/sfp-machine.h has at the end of the file:
#ifdef __ARM_EABI__
...
#endif


Change the #ifdef to #ifdef 0.

I only tested that gcc -c emitted __addsf3, and that libgcc.a had addsf3.0 with __addsf3 function inside it.

Reply

0 a.surati over 4 years ago in reply to EnricoTabanelli

Okay. Those steps replaced the optimized code with the unoptimized one, afaics within the libgcc.a built.

Additionally, libgcc.a and gcc compiler redefine __addsf3 to __aeabi_fadd. Such redefinitions are applied to other functions too.

For the sake of testing a single function __addsf3, these additional changes (on top of earlier ones) were made:

gccsrc/gcc/config/arm/arm.c has:
...
set_optab_libfunc (add_optab, SFmode, "__aeabi_fadd");
...

Comment that line.

gccsrc/libgcc/config/arm/sfp-machine.h has at the end of the file:
#ifdef __ARM_EABI__
...
#endif


Change the #ifdef to #ifdef 0.

I only tested that gcc -c emitted __addsf3, and that libgcc.a had addsf3.0 with __addsf3 function inside it.

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