Re: [Qemu-devel] [PATCH 03/14] target-ppc: Use float64 arg in helper_compute_fprf()

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Fri, Jan 06, 2017 at 09:01:17AM +1100, David Gibson wrote:
> On Thu, Jan 05, 2017 at 04:56:08PM +0530, Nikunj A Dadhania wrote:
> > From: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > 
> > Use float64 argument instead of unit64_t in helper_compute_fprf()
> > This allows code in helper_compute_fprf() to be reused later to
> > work with float128 argument too.
> > 
> > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> 
> Uh.. how can this possibly be correct, without updating the callers of
> helper_compute_fprf()?

It works currently because uint64_t argument that is passed by the
callers is interpreted as float64 arg (via farg.d).

Let me see if there is a cleaner way of doing this. Casting the
callers with right floatXX type seems to be the easiest way.
The requirement here is to ensure that

helper_compute_fprf_float16(CPUPPCState *env, float16 arg)
helper_compute_fprf_float32(CPUPPCState *env, float32 arg)
helper_compute_fprf_float64(CPUPPCState *env, float64 arg)
helper_compute_fprf_float128(CPUPPCState *env, float128 arg)

get autogenerated with right floatXX argument so that it can directly
be used with required routines (like floatXX_is_any_nan etc) w/o
needing the CPU_DoubleU or other intermediate forms.

Regards,
Bharata.