Den 15-03-2011 11:32, michael skrev:
I am trying to understand how to work with the various floating point options
available for FPC when running on ARM under Linux. I'm not to familiar with
all this so please bear with me.
Specifically I have a system comprising an TI OMAP3530: ARM CORTEX A8 running
Linaro. /proc/cpuinfo reports it as:
Processor : ARMv7 Processor rev 2 (v7l)
Features : swp half thumb fastmult vfp edsp neon vfpv3
I notice that when compiling for ARM GCC, by default, generates floating point
instructions like "fmuls s3, s11, s3" however if the -msoft-float option is
given then GCC generates calls to software floating point routines like "bl
__aeabi_fmul".
The former is somewhat faster and of course what I would like to achieve under
FPC.
So far I have managed to build, using the lazarus_first_time script, an FPC
cross compiler for ARM running on my PC, version 2.5.1.
Additionally I have built a native compiler on the ARM board from subversion
sources. Compiled using the ppcarm created on the PC.
I built the native compiler with a command like:
$make clean all PP=/path/to/ppcarm PREFIX="/opt/fpc-svn"
OPT="-dFPC_ARMEL -O- -dFPC_ABI_EABI"
The resulting compiler works on the target but it generates software floating
point instructions like "bl float64_mul".
Here I get stuck. I cannot get FPC to generate floating point instructions.
Adding any floating point options to FPC when compiling my application,
like -CfVFPV3, results in errors like:
PPU Loading /opt/fpc-svn/lib/fpc/2.5.1/units/arm-linux/rtl/system.ppu
Trying to use a unit which was compiled with a different FPU mode
Trying to rebuild my native compiler on the target with -CfVFPV3 in the
options fails with errors about "selected CPU does not support ARM
mode:....." for all of the floating point instructions generated.
Is there anyway to get FPC to generate floating point code similar to that
produced by GCC by default?
Is there a way to rebuild just the units such that they are in the same FPU
mode?
Thanks for any help.
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I think that it should work if you do it like:
make clean all PP=/path/to/ppcarm PREFIX="/opt/fpc-svn" OPT="-dFPC_ARMEL -O-
-dFPC_ABI_EABI -CfVFPv3"
It could be that there are simply some options missing to gas. It should
generate assembler files. You could try to call the assembler manually
and see what options it takes. I think some versions need
"-march=armv7+vfp3" or something like that
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