powerpc simulator instruction question

powerpc simulator instruction question

[Joel Sherrill]

Hi,

Version: gdb 6.5 with ppc simulator enabled.

I have an RTEMS program which seems to have the FPU
enabled OK since it executes the instructions at
0x9a0, 0x9ac, and 0x9b0.  But it gets an exception
0x0700 at 0x9b4.

     9a0:       fd 8c 00 32     fmul    f12,f12,f0
     9a4:       c0 09 0c e0     lfs     f0,3296(r9)
     9a8:       39 21 00 48     addi    r9,r1,72
     9ac:       fd 8c 00 32     fmul    f12,f12,f0
     9b0:       fd a0 60 1e     fctiwz  f13,f12
     9b4:       7d a0 4f ae     stfiwx  f13,0,r9

The device tree file is:

  #address-cells 2
  /openprom/init/register/pvr 0xfffe0000
  /openprom/options/oea-memory-size 8388608

The code in question was compiled with -mcpu=603e.
I have tried starting the simulator with no model
argument (tar sim...), 603e (-m 603e) and 603 without
any difference.

The stfiwx was generated by gcc.

Is the stfiwx not implemented in the simulator? Not valid?

Any suggestions, patches?

I can provide the executable in question if it helps
someone.

Thanks.

--joel sherrill

Re: powerpc simulator instruction question

[Daniel Jacobowitz]

On Fri, Nov 17, 2006 at 01:53:27PM -0600, Joel Sherrill wrote:
> Is the stfiwx not implemented in the simulator? Not valid?

Looks unimplemented.  GCC didn't generate it until 2005.

-- 
Daniel Jacobowitz
CodeSourcery

Re: powerpc simulator instruction question

[Joel Sherrill]

Daniel Jacobowitz wrote:
> On Fri, Nov 17, 2006 at 01:53:27PM -0600, Joel Sherrill wrote:
>   
>> Is the stfiwx not implemented in the simulator? Not valid?
>>     
>
> Looks unimplemented.  GCC didn't generate it until 2005.
>
>   
I found some posts that indicate qemu only got a patch
for it in Oct 2006. :)

I have no idea how to read, modify, or use ppc-instructions
to add it.  How can I find the instruction in there?

How can I map that back to the 603e manual?

This is pretty deep in the bowels of something and quite picky.  :(

Is there any PPC expert willing to take a stab at it?

--joel

Re: powerpc simulator instruction question

[Daniel Jacobowitz]

On Fri, Nov 17, 2006 at 02:08:37PM -0600, Joel Sherrill wrote:
> Is there any PPC expert willing to take a stab at it?

I don't think that there are any recently active developers who
know the first thing about psim.

-- 
Daniel Jacobowitz
CodeSourcery

Re: powerpc simulator instruction question

[Joel Sherrill]

Daniel Jacobowitz wrote:
> On Fri, Nov 17, 2006 at 02:08:37PM -0600, Joel Sherrill wrote:
>   
>> Is there any PPC expert willing to take a stab at it?
>>     
>
> I don't think that there are any recently active developers who
> know the first thing about psim.
>
>   
Looking at the ChangeLog, I got the impression there were not many people
comfortable with serious changes. :(

--joel

Re: powerpc simulator instruction question

[Frank Ch. Eigler]

Joel Sherrill <joel.sherrill@oarcorp.com> writes:

> >> Is the stfiwx not implemented in the simulator? Not valid?
> > Looks unimplemented.  GCC didn't generate it until 2005.
> I have no idea how to read, modify, or use ppc-instructions
> to add it.  How can I find the instruction in there?

The individual instruction patterns are the lines looking like "0.31,....".
The parts before the colons describe the instruction encoding, breaking
down the bits into operand fields and opcode numbers.  For example:

0.31,6.RT,11./,16./,21.83,31./:X:::Move From Machine State Register

means: bits 0..5  contain the value 31
            6..10 contain the field "RT" (use the expression *rT in the body)
            11..15 contain a don't care field
            16..20 likewise
            21..30 contains the value 83
            31     contains a don't care field

*601: PPC_UNIT_IU,    PPC_UNIT_IU,    1,  1,  0
*603: PPC_UNIT_SRU,   PPC_UNIT_SRU,   1,  1,  0
*603e:PPC_UNIT_SRU,   PPC_UNIT_SRU,   1,  1,  0
*604: PPC_UNIT_MCIU,  PPC_UNIT_MCIU,  3,  3,  0

These are functional unit utilization/performance numbers.
 
        if (IS_PROBLEM_STATE(processor))
          program_interrupt(processor, cia,
                            privileged_instruction_program_interrupt);
        else {
          *rT = MSR;
          check_masked_interrupts(processor);
        }

This code actually implements the instruction.


- FChE