DFA Instruction Output for VLIW

[Dan Towner]

Vlad,

>   The interfaces of all gcc utilities (genattrtab, genattr, gen...) are not
> described in the documentation.  Now no one port uses queried units.  It was
> used in an experimental patch for ia64 port.  I am still going to use it for
> ia64 port in near future.
> 
> The first of all you should define macro
> 
>   #define CPU_UNITS_QUERY 1
> 
> in <port>.h file to switch on code for querying units.
> 
> After that you should get an internal code of queried unit with the aid of
> function
> 
>   int get_cpu_unit_code (char *unit_name);
> 
> To figure out that the unit is reserved in given state, you should use the
> function
> 
>    int cpu_unit_reservation_p (void *state, int code);
> 
> The function returns nonzero if the unit with given code is reserved in given
> state.
> 
> I put the part of the old patch for ia64 as an example.

Many thanks. However, I am not totally sure what is happening. I tried
distilling your code down to remove the bits I thought were unnecessary.
I've attached my attempt below. 
If my understanding of the code is correct, the code determines the
state of the current instruction, and then updates that state from
instruction to instruction. Some of the code uses temp_state, which
appears to locally update the state to determine the state over the next
few cycles, but I have removed this as I am only interested in the
current state. When I run the code below by calling cc1 directly, the
code works fine, and outputs the  assigned slots. However, if I run the
scheduler using gcc, or using cc1 with -da, the code consistently
abort's when checking: 

  if (state_transition (currentState, insn) != -1)
    abort ();

I can't see any reason why the code should behave differently.

Thanks for your help. I am impressed with the DFA scheduler, because it
has allowed me to quickly and easily define the pipeline/VLIW attributes
for my port - I just need to extract them into the assembly language
now!

Dan.

void
picochip_final_prescan_insn (insn, operand, num_operands)
     rtx insn;
     rtx *operand;
     int num_operands;
{
  static state_t currentState;
  static int slot0Id, slot1Id, slot2Id;
  size_t size;
  state_t tempState;
  int i;
  rtx curr_insn;

  // Initialise the CPU identity codes and state.
  if (currentState == NULL) 
    {
      currentState = xmalloc (state_size());
      state_reset(currentState);
      slot0Id = get_cpu_unit_code("slot0");
      slot1Id = get_cpu_unit_code("slot1");
      slot2Id = get_cpu_unit_code("slot2");

      if (slot0Id < 0 || slot1Id < 0 || slot2Id < 0)
	abort();
    }

  printf("final_prescan for insn %d\n", INSN_UID(insn));

  if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
    abort ();

  for (i = GET_MODE (insn); i != 0; i--)
    {
#ifdef DFA_SCHEDULER_PRE_CYCLE_INSN
      state_transition (currentState, DFA_SCHEDULER_PRE_CYCLE_INSN);
#endif
      state_transition (currentState, NULL);
    } 

  if (INSN_CODE (insn) < 0)
    return;
  if (state_transition (currentState, insn) != -1)
    abort ();


  if (cpu_unit_reservation_p (currentState, slot0Id))
    printf("-> Slot 0\n");
  if (cpu_unit_reservation_p (currentState, slot1Id))
    printf("-> Slot 1\n");
  if (cpu_unit_reservation_p (currentState, slot2Id))
    printf("-> Slot 2\n");

  if (GET_CODE (insn) != JUMP_INSN)
    for (curr_insn = insn;;)
      {
	curr_insn = next_nonnote_insn (curr_insn);
	if (curr_insn == NULL || GET_RTX_CLASS (GET_CODE (curr_insn)) != 'i'
	    || GET_CODE (PATTERN (curr_insn)) != CLOBBER
	    && GET_CODE (PATTERN (curr_insn)) != USE)
	  break;
      }
  if (GET_CODE (insn) == JUMP_INSN || curr_insn == NULL
      || GET_RTX_CLASS (GET_CODE (curr_insn)) != 'i'
      || GET_CODE (PATTERN (curr_insn)) == ASM_INPUT
      || asm_noperands (PATTERN (curr_insn)) >= 0)
    state_reset (currentState);

}

=============================================================================
Daniel Towner
picoChip Designs Ltd., Riverside Buildings, 108, Walcot Street, BATH,
BA1 5BG
dant@picochip.com
07786 702589