Re: [Qemu-devel] [PATCH 11/15] tcg: split cpu_set_mxcsr()/cpu_set_fpuc()

[Zhong Yang <yang.zhong@intel.com>]

On Wed, Jun 21, 2017 at 03:15:25PM +0200, Paolo Bonzini wrote:
> 
> 
> On 21/06/2017 12:19, Yang Zhong wrote:
> > Split the cpu_set_mxcsr()/cpu_set_fpuc() with specific tcg code.
> > tcg_update_mxcsr()/tcg_set_fpuc() need be implemented in tcg-stub.c
> > file if tcg is disabled.
> > 
> > Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> > ---
> >  accel/stubs/tcg-stub.c   |  8 ++++++++
> >  target/i386/cpu.h        | 15 +++++++++++++--
> >  target/i386/fpu_helper.c |  8 +++-----
> >  3 files changed, 24 insertions(+), 7 deletions(-)
> > 
> > diff --git a/accel/stubs/tcg-stub.c b/accel/stubs/tcg-stub.c
> > index dafb1d0..91625a8 100644
> > --- a/accel/stubs/tcg-stub.c
> > +++ b/accel/stubs/tcg-stub.c
> > @@ -75,6 +75,14 @@ void dump_opcount_info(FILE *f, fprintf_function cpu_fprintf)
> >  {
> >  }
> >  
> > +void tcg_update_mxcsr(CPUX86State *env)
> > +{
> > +}
> > +
> > +void tcg_set_fpuc(CPUX86State *env)
> > +{
> > +}
> > +
> >  void cpu_loop_exit(CPUState *cpu)
> >  {
> >      abort();
> > diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> > index 8b3b535..229b216 100644
> > --- a/target/i386/cpu.h
> > +++ b/target/i386/cpu.h
> > @@ -1643,8 +1643,19 @@ static inline int32_t x86_get_a20_mask(CPUX86State *env)
> >  }
> >  
> >  /* fpu_helper.c */
> > -void cpu_set_mxcsr(CPUX86State *env, uint32_t val);
> > -void cpu_set_fpuc(CPUX86State *env, uint16_t val);
> > +void tcg_update_mxcsr(CPUX86State *env);
> > +void tcg_set_fpuc(CPUX86State *env);
> > +static inline void cpu_set_mxcsr(CPUX86State *env, uint32_t mxcsr)
> > +{
> > +    env->mxcsr = mxcsr;
> > +    tcg_update_mxcsr(env);
> 
> Instead of having to add stubs, please guard the call with "if
> (tcg_enabled())".  Same below.
> 
> Paolo
>
  Hello Paolo,

  Got it! thanks!

  From your comments + Richard Henderson's comments, i got below guideline
  (1) accel/stubs/tcg-stub.c
      This file is target-independent file, do not add x86-specific stubs functions into this file.

  (2) there are three kind of methods to mask TCG relative function
      a) if(tcg_enabled())
      b) if CONFIG_TCG
      c) stub function

  Paolo, which one is your prefer?  a) ?  please also make sure your prefer sequence, a) > b) > c) ?
  

  Yang
  
 
> > +}
> > +
> > +static inline void cpu_set_fpuc(CPUX86State *env, uint16_t fpuc)
> > +{
> > +     env->fpuc = fpuc;
> > +     tcg_set_fpuc(env);
> > +}
> >  
> >  /* mem_helper.c */
> >  void helper_lock_init(void);
> > diff --git a/target/i386/fpu_helper.c b/target/i386/fpu_helper.c
> > index 34fb5fc..a7550c9 100644
> > --- a/target/i386/fpu_helper.c
> > +++ b/target/i386/fpu_helper.c
> > @@ -1550,12 +1550,11 @@ void helper_xsetbv(CPUX86State *env, uint32_t ecx, uint64_t mask)
> >  #define SSE_RC_CHOP         0x6000
> >  #define SSE_FZ              0x8000
> >  
> > -void cpu_set_mxcsr(CPUX86State *env, uint32_t mxcsr)
> > +void tcg_update_mxcsr(CPUX86State *env)
> >  {
> > +    uint32_t mxcsr = env->mxcsr;
> >      int rnd_type;
> >  
> > -    env->mxcsr = mxcsr;
> > -
> >      /* set rounding mode */
> >      switch (mxcsr & SSE_RC_MASK) {
> >      default:
> > @@ -1581,9 +1580,8 @@ void cpu_set_mxcsr(CPUX86State *env, uint32_t mxcsr)
> >      set_flush_to_zero((mxcsr & SSE_FZ) ? 1 : 0, &env->fp_status);
> >  }
> >  
> > -void cpu_set_fpuc(CPUX86State *env, uint16_t val)
> > +void tcg_set_fpuc(CPUX86State *env)
> >  {
> > -    env->fpuc = val;
> >      update_fp_status(env);
> >  }
> >  
> >