On 05/08/2022 13:20, Alex Bennée wrote:
"Lucas Mateus Castro(alqotel)"<lucas.ara...@eldorado.org.br> writes:
From: "Lucas Mateus Castro (alqotel)"<lucas.ara...@eldorado.org.br>
Changes in v2:
- Completely reworked the solution:
* Created re_bias in FloatFmt, it is 3/4 of the total exponent
range of a FP type
I thought this might have an effect on the efficiency of the FloatFmt
extraction/packing but I couldn't see any real difference in fpbench. I
doubt the compiler can dead code it away if not used by a front-end.
Anyway have a:
Reviewed-by: Alex Bennée<alex.ben...@linaro.org>
for the series.
* Added rebias bools that dictates if the result should have
its exponent add/subtract the re_bias value if an
overflow/underflow occurs.
* ppc_store_fpscr sets/unsets rebias if OE/UE is set/unset
The PowerISA defines that if an overflow exception happen with FPSCR.OE
set, the exponent of the intermediate result is subtracted 1536 in
double precision operations and is added 1536 in an underflow exception,
currently this behavior is not QEMU's behavior, this patch series fixes
that.
Currently there's no test in this patch series as there's no way to
disable MSR.FE0 and MSR.FE1 in linux user, so any overflow/underflow
exception with OE/UE set causes a trapping exception.
Could you do it with a system mode test? Probably overkill for this
though. I suspect tweaking testfloat would be tricky.
Matheus currently has a patch to enable prctl, it still needs to change
some places that have hardcoded values for linux-user
(https://github.com/PPC64/qemu/tree/alqotel-ferst-prctl-patch has
Matheus' patch and a patch to remove the ifdef from fp_exceptions_enabled).
With that change it should be possible to create a normal test for this
(I sent a basic one along with v1,
Message-Id=<20220803124324.23593-1-lucas.ara...@eldorado.org.br>) built
on top of that branch.
Thanks,
Lucas Mateus Castro (alqotel) (2):
fpu: Add rebias bool, value and operation
target/ppc: Bugfix FP when OE/UE are set
fpu/softfloat-parts.c.inc | 21 +++++++++++++++++++--
fpu/softfloat.c | 2 ++
include/fpu/softfloat-types.h | 4 ++++
target/ppc/cpu.c | 2 ++
target/ppc/fpu_helper.c | 2 --
5 files changed, 27 insertions(+), 4 deletions(-)
--
Alex Bennée
--
Lucas Mateus M. Araujo e Castro
Instituto de Pesquisas ELDORADO
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Departamento Computação Embarcada
Analista de Software Trainee
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