[v3,0/3] target/ppc: Fix FPSCR.FI bit

Message

Víctor Colombo May 17, 2022, 4:15 p.m. UTC

Hello everyone,

According to Power ISA, the FI bit in FPSCR is non-sticky.
This means that if an instruction is said to modify the FI bit, then
it should be set or cleared depending on the result of the
instruction. Otherwise, it should be kept as was before.

This patch set fixes inconsistencies found in QEMU's handling of the
FPSCR.FI bit, where it's treating as all instructions are supposed
to change FI.

Thanks!

v2:
- move the FI change from float_inexact_excp to do_float_check_status
- remove the setting of FI from float_overflow_excp, making
  do_float_check_status() the only responsible for it.
- make float_overflow_excp() return float_flag_inexact if it should
  update the inexact flags.
- Add patch 3, moving the renaming of sfprf to sfifprf to it
  (previously on patch 1)

v3:
- rewrite patch 1 commit message
- fix missing comment change in patch 3
- add all R-b

Víctor Colombo (3):
  target/ppc: Fix FPSCR.FI bit being cleared when it shouldn't
  target/ppc: Fix FPSCR.FI changing in float_overflow_excp()
  target/ppc: Rename sfprf to sfifprf where it's also used as set fi
    flag

 target/ppc/cpu.h        |   2 +
 target/ppc/fpu_helper.c | 223 +++++++++++++++++++++-------------------
 2 files changed, 117 insertions(+), 108 deletions(-)

Comments

Daniel Henrique Barboza May 23, 2022, 6:16 p.m. UTC | #1

Queued in gitlab.com/danielhb/qemu/tree/ppc-next. Thanks,


Daniel

On 5/17/22 13:15, Víctor Colombo wrote:
> Hello everyone,
> 
> According to Power ISA, the FI bit in FPSCR is non-sticky.
> This means that if an instruction is said to modify the FI bit, then
> it should be set or cleared depending on the result of the
> instruction. Otherwise, it should be kept as was before.
> 
> This patch set fixes inconsistencies found in QEMU's handling of the
> FPSCR.FI bit, where it's treating as all instructions are supposed
> to change FI.
> 
> Thanks!
> 
> v2:
> - move the FI change from float_inexact_excp to do_float_check_status
> - remove the setting of FI from float_overflow_excp, making
>    do_float_check_status() the only responsible for it.
> - make float_overflow_excp() return float_flag_inexact if it should
>    update the inexact flags.
> - Add patch 3, moving the renaming of sfprf to sfifprf to it
>    (previously on patch 1)
> 
> v3:
> - rewrite patch 1 commit message
> - fix missing comment change in patch 3
> - add all R-b
> 
> Víctor Colombo (3):
>    target/ppc: Fix FPSCR.FI bit being cleared when it shouldn't
>    target/ppc: Fix FPSCR.FI changing in float_overflow_excp()
>    target/ppc: Rename sfprf to sfifprf where it's also used as set fi
>      flag
> 
>   target/ppc/cpu.h        |   2 +
>   target/ppc/fpu_helper.c | 223 +++++++++++++++++++++-------------------
>   2 files changed, 117 insertions(+), 108 deletions(-)
>