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Re: Toolchain for Maverick Crunch FPU
Richard Earnshaw wrote:
On Thu, 2007-04-12 at 14:16 +0300, Kai Ruottu wrote:
Things seem to be that the '-mcpu=ep9312 -mhard-float' combination will
crash the GCC build in both gcc-4.1.2 and gcc-4.2.0-20070316 prerelease
like :
-mhard-float doesn't do what you think it does...
I think you should be using:
-mcpu=ep9312 -mfpu=maverick -mfloat-abi=softfp
Thanks, I implemented these default options for ep93xx in a separate
'ep9312-elf' target, now
there was that common
arm*-*-elf | ep9312-*-elf)
template in gcc/config.gcc. The 'xscale-elf' (and '-coff') were
separate already, so
putting the 'ep9312-*-elf' as a separate one with a separate
'gcc/config/arm/t-ep9312-elf'
(derived from the 't-arm-elf') Makefile fragment for its (possibly)
required multilibs, sounded
much simplier than touching the 'arm-elf' multilib definitions in the
'gcc/config/arm/t-arm-elf'
(now made suitable for my self-chosen 'arm-elf' variations)...
It seemed to be that the changes I made in gcc-4.1.2 (here against the
pristine gcc-4.1 snapshots) :
*** ../../gcc-4.1-20070409/gcc/config.gcc Mon Oct 16 02:12:23 2006
--- ./config.gcc Thu Apr 12 16:51:25 2007
***************
*** 2460,2466 ****
if test x$with_float = x; then
case ${target} in
ep9312-*-*)
! with_float=hard
;;
esac
fi
--- 2460,2467 ----
if test x$with_float = x; then
case ${target} in
ep9312-*-*)
! with_fpu=maverick
! with_float=softfp
;;
esac
fi
didn't trigger the required '-D__SOFTFP__' but they triggered the
'-D__MAVERICK__',
so just editing the 'gcc/config/arm/ieee754-[ds]f.S' to have a :
#if !defined (__VFP_FP__) && !defined(__SOFTFP__) && !defined(__MAVERICK__)
where the last one was earlier missing, seemed suitable for my lazy
mind... So these three
predefines were taken meaning the same in this respect.... The
'gcc/config.gcc' also required
a patch like :
***************
*** 2501,2507 ****
done
;;
! arm*-*-*)
supported_defaults="arch cpu float tune fpu abi"
for which in cpu tune; do
# See if it matches any of the entries in
arm-cores.def
--- 2502,2508 ----
done
;;
! arm*-*-* | ep9312-*-*)
supported_defaults="arch cpu float tune fpu abi"
for which in cpu tune; do
# See if it matches any of the entries in
arm-cores.def
in order to get those '--with-' options accepted for 'ep9312-*' too...
The main 'config.sub' also required adding the 'ep9312' as an accepted
CPU type. After
these fixes the configure and build succeeded... Please correct me if
something sounds
still being wrong!
The resulted compiler now replaces some opcodes with others like :
*** fp_ep9312-2.s Wed Apr 11 22:12:43 2007
--- fp_ep9312-3.s Thu Apr 12 21:38:35 2007
***************
*** 30,36 ****
ldr r0, [r5, #0] @ float
ldr r1, [r2, #0] @ float
bl __divsf3
! cfstrs mvf0, [r4, #0]
cfldrs mvf0, [r4, #0]
cfldrs mvf1, [r5, #0]
cfadds mvf0, mvf0, mvf1
--- 30,36 ----
ldr r0, [r5, #0] @ float
ldr r1, [r2, #0] @ float
bl __divsf3
! str r0, [r4, #0] @ float
cfldrs mvf0, [r4, #0]
cfldrs mvf1, [r5, #0]
cfadds mvf0, mvf0, mvf1
when compared to the earlier 'arm-elf' targeted one with '-mcpu=ep9312
-mhard-float'...
For me it looks like '__divsf3' now returning something in register 'r0'
instead of 'mvf0'.
To get the 'arm-elf' one to produce code with your '-mcpu=ep9312
-mfpu=maverick
-mfloat-abi=softfp' when getting the bare '-mcpu=ep9312' should succeed
via tinkering
the settings for 'specs', I remember once enabling the '-msoft-float'
for 'i386-elf' and I
remember this also requiring the '-mno-fp-ret-in-387' or something to
tell that there
really wasn't any 'i387' present with its FPU-registers as default....