On Sun, Jun 24, 2018 at 07:12:48PM -0400, John Arbuckle wrote: > The FPSCR[FI] bit indicates if the last floating point instruction had a > result that was rounded. Each consecutive floating point instruction is > suppose to set this bit to the correct value. What currently happens is this > bit is not set as often as it should be. I have verified that this is the > behavior of a real PowerPC 950. This patch fixes that problem by deciding to > set this bit after each floating point instruction. > > https://www.pdfdrive.net/powerpc-microprocessor-family-the-programming-environments-for-32-e3087633.html > Page 63 in table 2-4 is where the description of this bit can be found. > > Signed-off-by: John Arbuckle <programmingk...@gmail.com>
I'm not sure it's the nicest way to fix it, but the existing code is
pretty horrible, so, whatever.
It looks correct, so, applied to ppc-for-3.0.
> ---
> target/ppc/fpu_helper.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/target/ppc/fpu_helper.c b/target/ppc/fpu_helper.c
> index d31a933cbb..9c841864c8 100644
> --- a/target/ppc/fpu_helper.c
> +++ b/target/ppc/fpu_helper.c
> @@ -274,6 +274,7 @@ static inline void float_inexact_excp(CPUPPCState *env)
> {
> CPUState *cs = CPU(ppc_env_get_cpu(env));
>
> + env->fpscr |= 1 << FPSCR_FI;
> env->fpscr |= 1 << FPSCR_XX;
> /* Update the floating-point exception summary */
> env->fpscr |= FP_FX;
> @@ -505,6 +506,7 @@ static void do_float_check_status(CPUPPCState *env,
> uintptr_t raddr)
> {
> CPUState *cs = CPU(ppc_env_get_cpu(env));
> int status = get_float_exception_flags(&env->fp_status);
> + bool inexact_happened = false;
>
> if (status & float_flag_divbyzero) {
> float_zero_divide_excp(env, raddr);
> @@ -514,6 +516,12 @@ static void do_float_check_status(CPUPPCState *env,
> uintptr_t raddr)
> float_underflow_excp(env);
> } else if (status & float_flag_inexact) {
> float_inexact_excp(env);
> + inexact_happened = true;
> + }
> +
> + /* if the inexact flag was not set */
> + if (inexact_happened == false) {
> + env->fpscr &= ~(1 << FPSCR_FI); /* clear the FPSCR[FI] bit */
> }
>
> if (cs->exception_index == POWERPC_EXCP_PROGRAM &&
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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