On 11/24/21 6:25 PM, Lucas Mateus Castro (alqotel) wrote:
mtfsf, mtfsfi and mtfsb1 instructions call helper_float_check_status
after updating the value of FPSCR, but helper_float_check_status
checks fp_status and fp_status isn't updated based on FPSCR and
since the value of fp_status is reset earlier in the instruction,
it's always 0.
Because of this helper_float_check_status would change the FI bit to 0
as this bit checks if the last operation was inexact and
float_flag_inexact is always 0.
These instructions also don't throw exceptions correctly since
helper_float_check_status throw exceptions based on fp_status.
This commit created a new helper, helper_fpscr_check_status that checks
FPSCR value instead of fp_status and checks for a larger variety of
exceptions than do_float_check_status.
Since fp_status isn't used, gen_reset_fpstatus() was removed.
The hardware used to compare QEMU's behavior to was a Power9.
Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.ara...@eldorado.org.br>
---
target/ppc/fpu_helper.c | 48 ++++++++++++++++++++++++++++++
target/ppc/helper.h | 1 +
target/ppc/translate/fp-impl.c.inc | 9 ++----
3 files changed, 52 insertions(+), 6 deletions(-)
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
r~
