Re: CGEN: RFA: Fast vs Full with scache-pbb

[Dave Brolley <brolley at redhat dot com>]

Approved by Frank and Ben and committed.

Dave

Dave Brolley wrote:
> 
> Hi,
> 
> The simulator port I'm working on was crashing when the sim was
> run without -t. It is configured with-scache-pbb.
> 
> It turns out that the call to <cpu>_pbb_begin in the generated
> <cpu>_sem_x_begin was passing STATE_RUN_FAST_P (CPU_STATE
> (current_cpu)) as the 'fast_p' argument. Now this flag will be 0
> if -t is specified and 1 otherwise. However the rest of the
> generated code (mloop.c, sem.c) is not set up for dynamic
> fast/full switching (although it looks like some work was done
> toward this goal in the past). As a result, only the 'sem_full'
> function in the idesc_table is initialized for my build. Passing
> fast_p==1 causes the semantic engine to attempt to use 'sem_fast'
> function which is not initialized.
> 
> The attached patch changes <cpu>_sem_x_begin to honour any FAST_P
> macro which may be defined and to otherwise assume that
> FAST_P==0. I #if'd out the orignal code since it will apply
> someday when dynamic fast/full switching is enabled in the rest
> of the cgen-generated code.
> 
> OK to commit? Once again I tested on fr30, m32r and 2 internal
> ports which cover a range of sem-switch/non sem-switch/scache/pbb
> configurations.
> 
> Dave
> 
>   -----------------------------------------------------------------
> Index: sim.scm
> ===================================================================
> RCS file: /cvs/src/src/cgen/sim.scm,v
> retrieving revision 1.3
> diff -c -p -r1.3 sim.scm
> *** sim.scm     2000/08/24 15:35:47     1.3
> --- sim.scm     2000/09/01 18:38:15
> *************** struct scache {
> *** 1884,1895 ****
>         "--begin--" () () '(c-code VOID "\
>     {
>   #if WITH_SCACHE_PBB_@CPU@
> ! #ifdef DEFINE_SWITCH
>       /* In the switch case FAST_P is a constant, allowing several optimizations
>          in any called inline functions.  */
>       vpc = @cpu@_pbb_begin (current_cpu, FAST_P);
>   #else
>       vpc = @cpu@_pbb_begin (current_cpu, STATE_RUN_FAST_P (CPU_STATE (current_cpu)));
>   #endif
>   #endif
>     }
> --- 1884,1899 ----
>         "--begin--" () () '(c-code VOID "\
>     {
>   #if WITH_SCACHE_PBB_@CPU@
> ! #if defined DEFINE_SWITCH || defined FAST_P
>       /* In the switch case FAST_P is a constant, allowing several optimizations
>          in any called inline functions.  */
>       vpc = @cpu@_pbb_begin (current_cpu, FAST_P);
>   #else
> + #if 0 /* cgen engine can't handle dynamic fast/full switching yet.  */
>       vpc = @cpu@_pbb_begin (current_cpu, STATE_RUN_FAST_P (CPU_STATE (current_cpu)));
> + #else
> +     vpc = @cpu@_pbb_begin (current_cpu, 0);
> + #endif
>   #endif
>   #endif
>     }