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Soft floating point emulation problems
- To: linux at lists dot arm dot linux dot org dot uk, gcc at gcc dot gnu dot org
- Subject: Soft floating point emulation problems
- From: cyril dot germond at philips dot com
- Date: Mon, 22 Oct 2001 17:10:35 +0200
Just to introduce the problem, here is a summary of what I have done.
I work on an Linux port on an ARM based hardware without hw floating point support with the GNU toolchain.
I *finally* managed to compile the glibc 2.2.4 for an arm-linux configuration for 2.2.4 Kernel on a Linux host (2.2.14-5.0smp). I used binutils 2.11.2 and gcc 2.95.3.
The parameters I have used for configuration were the following:
-v 2>&1 | tee configure.out
I first generated a glibc (just typing make, with the default Makefiles).
First problem, it seems that the --without-fp has not the expected effects, has the generated libraries contained a lot of floating point instructions (it can be checked by typing arm-linux-objdump -d)...
Then, I tried to pass explicitly -msoft-float to gcc as an argument, to ensure that no fp instruction is used in the code generation. So I finally edited the Makeconfig file to change the default arguments given to gcc (adding -msoft-float). I finally
managed to build the glibc (this noon).
Even if the process dramatically reduced the number of floating points instructions, there are still a few ones...where they should not be (AFAIK)!!!
For example, in the library libm.a, there are 3 stf instructions.
290: adad51ec stfges f5, [sp, #944]!
308: bd241146 stflts f1, [r4, -#280]!
470: bd241146 stflts f1, [r4, -#280]!
I am quite confused !
I am wondering if I should have had generated gcc itsel with some kind of -msoft-float option (it was generated with -nfp in the configuration script).
Maybe is it a gcc configuration bug ?
Has anyone information about this problem ?
Does anyone know where could I find a set of floating-point instructions library ?
Thanks and regards,
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