Builiding not optimized Libgcc for ARM Cortex-M4 target

Builiding not optimized Libgcc for ARM Cortex-M4 target

[Enrico Tabanelli]

Good morning,

I am trying to compile Libgcc for the ARM Cortex-M4 target from scratch since I need to compare Floating Point SW emulation on an ARM Cortex-M4 and Risc-V based processors. By default, GCC includes an optimized version of the FP SW emulation routines, ieee754-sf.S, which is included in the ARM back-end of Libgcc. For my work, I would like to use the basic routines included in libgcc/softfp.
Does anyone know how to exclude ieee754-sf.S in the libgcc building process? In particular, how to configure GCC and if there is something to change inside the ARM back-end?

Thanks,
Enrico Tabanelli

Re: Builiding not optimized Libgcc for ARM Cortex-M4 target

[Richard Earnshaw]

On 24/11/2020 20:47, Enrico Tabanelli via Gcc-help wrote:
> Good morning,
> 
> I am trying to compile Libgcc for the ARM Cortex-M4 target from scratch since I need to compare Floating Point SW emulation on an ARM Cortex-M4 and Risc-V based processors. By default, GCC includes an optimized version of the FP SW emulation routines, ieee754-sf.S, which is included in the ARM back-end of Libgcc. For my work, I would like to use the basic routines included in libgcc/softfp.
> Does anyone know how to exclude ieee754-sf.S in the libgcc building process? In particular, how to configure GCC and if there is something to change inside the ARM back-end?
> 
> Thanks,
> Enrico Tabanelli
> 

I think you'd need to hack the build system.  I'm not aware of any
standard configuration hooks to do this.

R.

Re: Builiding not optimized Libgcc for ARM Cortex-M4 target

[Enrico Tabanelli]

Hi Richard,

Do you know how to hack the build system properly to exclude the optimized routines?

Enrico
________________________________
From: Richard Earnshaw <Richard.Earnshaw@foss.arm.com>
Sent: Thursday, December 3, 2020 12:59 PM
To: Enrico Tabanelli <enrico.tabanelli3@unibo.it>; gcc-help@gcc.gnu.org <gcc-help@gcc.gnu.org>
Subject: Re: Builiding not optimized Libgcc for ARM Cortex-M4 target

On 24/11/2020 20:47, Enrico Tabanelli via Gcc-help wrote:
> Good morning,
>
> I am trying to compile Libgcc for the ARM Cortex-M4 target from scratch since I need to compare Floating Point SW emulation on an ARM Cortex-M4 and Risc-V based processors. By default, GCC includes an optimized version of the FP SW emulation routines, ieee754-sf.S, which is included in the ARM back-end of Libgcc. For my work, I would like to use the basic routines included in libgcc/softfp.
> Does anyone know how to exclude ieee754-sf.S in the libgcc building process? In particular, how to configure GCC and if there is something to change inside the ARM back-end?
>
> Thanks,
> Enrico Tabanelli
>

I think you'd need to hack the build system.  I'm not aware of any
standard configuration hooks to do this.

R.

Re: Builiding not optimized Libgcc for ARM Cortex-M4 target

[Richard Earnshaw]

On 03/12/2020 21:24, Enrico Tabanelli wrote:
> Hi Richard,
> 
> Do you know how to hack the build system properly to exclude the
> optimized routines?

Sorry, not in detail.  Most of the changes will probably be in
libgcc/config/arm; but you may also need to make changes to
gcc/config/arm/arm.c to handle the function names that are used when
calling the soft-float C code.

R.

> 
> Enrico
> ------------------------------------------------------------------------
> *From:* Richard Earnshaw <Richard.Earnshaw@foss.arm.com>
> *Sent:* Thursday, December 3, 2020 12:59 PM
> *To:* Enrico Tabanelli <enrico.tabanelli3@unibo.it>;
> gcc-help@gcc.gnu.org <gcc-help@gcc.gnu.org>
> *Subject:* Re: Builiding not optimized Libgcc for ARM Cortex-M4 target
>  
> On 24/11/2020 20:47, Enrico Tabanelli via Gcc-help wrote:
>> Good morning,
>> 
>> I am trying to compile Libgcc for the ARM Cortex-M4 target from scratch since I need to compare Floating Point SW emulation on an ARM Cortex-M4 and Risc-V based processors. By default, GCC includes an optimized version of the FP SW emulation routines, ieee754-sf.S, which is included in the ARM back-end of Libgcc. For my work, I would
> like to use the basic routines included in libgcc/softfp.
>> Does anyone know how to exclude ieee754-sf.S in the libgcc building process? In particular, how to configure GCC and if there is something to change inside the ARM back-end?
>> 
>> Thanks,
>> Enrico Tabanelli
>> 
> 
> I think you'd need to hack the build system.  I'm not aware of any
> standard configuration hooks to do this.
> 
> R.