pdp11.c

gcc库的原代码,对编程有很大帮助.

    switch (length)
    {
      case 1:
	
	strcpy(buf, pos);
	strcat(buf, " %l0");
	
	return buf;
	
      case 3:
	
	sprintf(buf, "%s JMP_%d\n\tjmp %%l0\nJMP_%d:", neg, x, x);
	
	x++;
	
	return buf;
	
      default:
	
	abort();
    }
    
}

void
notice_update_cc_on_set(exp, insn)
  rtx exp;
  rtx insn;
{
    if (GET_CODE (SET_DEST (exp)) == CC0)
    { 
	cc_status.flags = 0;					
	cc_status.value1 = SET_DEST (exp);			
	cc_status.value2 = SET_SRC (exp);			

/*
	if (GET_MODE(SET_SRC(exp)) == DFmode)
	    cc_status.flags |= CC_IN_FPU;
*/	
    }							
    else if ((GET_CODE (SET_DEST (exp)) == REG		
	      || GET_CODE (SET_DEST (exp)) == MEM)		
	     && GET_CODE (SET_SRC (exp)) != PC		
	     && (GET_MODE (SET_DEST(exp)) == HImode		
		 || GET_MODE (SET_DEST(exp)) == QImode)	
		&& (GET_CODE (SET_SRC(exp)) == PLUS		
		    || GET_CODE (SET_SRC(exp)) == MINUS	
		    || GET_CODE (SET_SRC(exp)) == AND	
		    || GET_CODE (SET_SRC(exp)) == IOR	
		    || GET_CODE (SET_SRC(exp)) == XOR	
		    || GET_CODE (SET_SRC(exp)) == NOT	
		    || GET_CODE (SET_SRC(exp)) == NEG	
			|| GET_CODE (SET_SRC(exp)) == REG	
		    || GET_CODE (SET_SRC(exp)) == MEM))	
    { 
	cc_status.flags = 0;					
	cc_status.value1 = SET_SRC (exp);   			
	cc_status.value2 = SET_DEST (exp);			
	
	if (cc_status.value1 && GET_CODE (cc_status.value1) == REG	
	    && cc_status.value2					
	    && reg_overlap_mentioned_p (cc_status.value1, cc_status.value2))
    	    cc_status.value2 = 0;					
	if (cc_status.value1 && GET_CODE (cc_status.value1) == MEM	
	    && cc_status.value2					
	    && GET_CODE (cc_status.value2) == MEM)			
	    cc_status.value2 = 0; 					
    }							
    else if (GET_CODE (SET_SRC (exp)) == CALL)		
    { 
	CC_STATUS_INIT; 
    }
    else if (GET_CODE (SET_DEST (exp)) == REG)       		
	/* what's this ? */					
    { 
	if ((cc_status.value1					
	     && reg_overlap_mentioned_p (SET_DEST (exp), cc_status.value1)))
	    cc_status.value1 = 0;				
	if ((cc_status.value2					
	     && reg_overlap_mentioned_p (SET_DEST (exp), cc_status.value2)))
	    cc_status.value2 = 0;				
    }							
    else if (SET_DEST(exp) == pc_rtx)
    { 
	/* jump */
    }
    else /* if (GET_CODE (SET_DEST (exp)) == MEM)	*/	
    {  
	/* the last else is a bit paranoiac, but since nearly all instructions 
	   play with condition codes, it's reasonable! */

	CC_STATUS_INIT; /* paranoia*/ 
    }		        
}


int simple_memory_operand(op, mode)
  rtx op;
  enum machine_mode mode;
{
    rtx addr, plus0, plus1;
    int offset = 0;

    /* Eliminate non-memory operations */
    if (GET_CODE (op) != MEM)
	return FALSE;

#if 0
    /* dword operations really put out 2 instructions, so eliminate them.  */
    if (GET_MODE_SIZE (GET_MODE (op)) > (HAVE_64BIT_P () ? 8 : 4))
	return FALSE;
#endif

    /* Decode the address now.  */

  indirection:
    
    addr = XEXP (op, 0);

    switch (GET_CODE (addr))
    {
      case REG:
	/* (R0) - no extra cost */
	return 1;
	
      case PRE_DEC:
      case POST_INC:
	/* -(R0), (R0)+ - cheap! */
	return 0;
	
      case MEM:
	/* cheap - is encoded in addressing mode info! 

	   -- except for @(R0), which has to be @0(R0) !!! */

	if (GET_CODE (XEXP (addr, 0)) == REG)
	    return 0;
	
	op=addr;
	goto indirection;
	
      case CONST_INT:
      case LABEL_REF:	       
      case CONST:
      case SYMBOL_REF:
	/* @#address - extra cost */
	return 0;

      case PLUS:
	/* X(R0) - extra cost */
	return 0;
    }
    
    return FALSE;
}


/*
 * output a block move:
 *
 * operands[0]	... to
 * operands[1]  ... from
 * operands[2]  ... length
 * operands[3]  ... alignment
 * operands[4]  ... scratch register
 */

 
char *
output_block_move(operands)
  rtx *operands;
{
    static int count = 0;
    char buf[200];
    
    if (GET_CODE(operands[2]) == CONST_INT
	&& TARGET_TIME)
    {
	if (INTVAL(operands[2]) < 16
	    && INTVAL(operands[3]) == 1)
	{
	    register int i;
	    
	    for (i = 1; i <= INTVAL(operands[2]); i++)
		output_asm_insn("movb (%1)+, (%0)+", operands);

	    return "";
	}
	else if (INTVAL(operands[2]) < 32)
	{
	    register int i;
	    
	    for (i = 1; i <= INTVAL(operands[2])/2; i++)
		output_asm_insn("mov (%1)+, (%0)+", operands);
	    
	    /* may I assume that moved quantity is 
	       multiple of alignment ???

	       I HOPE SO !
	    */

	    return "";
	}
	

	/* can do other clever things, maybe... */
    }

    if (CONSTANT_P(operands[2]) )
    {
	/* just move count to scratch */
	output_asm_insn("mov %2, %4", operands);
    }
    else
    {
	/* just clobber the register */
	operands[4] = operands[2];
    }
    

    /* switch over alignment */
    switch (INTVAL(operands[3]))
    {
      case 1:
	
	/* 
	  x:
	  movb (%1)+, (%0)+
	  
	  if (TARGET_45)
	     sob %4,x
	  else
	     dec %4
	     bgt x

	*/

	sprintf(buf, "\nmovestrhi%d:", count);
	output_asm_insn(buf, NULL);
	
	output_asm_insn("movb (%1)+, (%0)+", operands);
	
	if (TARGET_45)
	{
	    sprintf(buf, "sob %%4, movestrhi%d", count);
	    output_asm_insn(buf, operands);
	}
	else
	{
	    output_asm_insn("dec %4", operands);
	    
	    sprintf(buf, "bgt movestrhi%d", count);
	    output_asm_insn(buf, NULL);
	}
	
	count ++;
	break;
	
      case 2:
	
	/* 
	   asr %4

	   x:

	   mov (%1)+, (%0)+

	   if (TARGET_45)
	     sob %4, x
	   else
	     dec %4
	     bgt x
	*/

      generate_compact_code:

	output_asm_insn("asr %4", operands);

	sprintf(buf, "\nmovestrhi%d:", count);
	output_asm_insn(buf, NULL);
	
	output_asm_insn("mov (%1)+, (%0)+", operands);
	
	if (TARGET_45)
	{
	    sprintf(buf, "sob %%4, movestrhi%d", count);
	    output_asm_insn(buf, operands);
	}
	else
	{
	    output_asm_insn("dec %4", operands);
	    
	    sprintf(buf, "bgt movestrhi%d", count);
	    output_asm_insn(buf, NULL);
	}
	
	count ++;
	break;

      case 4:
	
	/*

	   asr %4
	   asr %4

	   x:

	   mov (%1)+, (%0)+
	   mov (%1)+, (%0)+

	   if (TARGET_45)
	     sob %4, x
	   else
	     dec %4
	     bgt x
	*/

	if (TARGET_SPACE)
	    goto generate_compact_code;
	
	output_asm_insn("asr %4", operands);
	output_asm_insn("asr %4", operands);

	sprintf(buf, "\nmovestrhi%d:", count);
	output_asm_insn(buf, NULL);
	
	output_asm_insn("mov (%1)+, (%0)+", operands);
	output_asm_insn("mov (%1)+, (%0)+", operands);
	
	if (TARGET_45)
	{
	    sprintf(buf, "sob %%4, movestrhi%d", count);
	    output_asm_insn(buf, operands);
	}
	else
	{
	    output_asm_insn("dec %4", operands);
	    
	    sprintf(buf, "bgt movestrhi%d", count);
	    output_asm_insn(buf, NULL);
	}
	
	count ++;
	break;
       
      default:
	
	/*
	   
	   asr %4
	   asr %4
	   asr %4

	   x:

	   mov (%1)+, (%0)+
	   mov (%1)+, (%0)+
	   mov (%1)+, (%0)+
	   mov (%1)+, (%0)+
	   
	   if (TARGET_45)
	     sob %4, x
	   else
	     dec %4
	     bgt x
	*/


	if (TARGET_SPACE)
	    goto generate_compact_code;
	
	output_asm_insn("asr %4", operands);
	output_asm_insn("asr %4", operands);
	output_asm_insn("asr %4", operands);

	sprintf(buf, "\nmovestrhi%d:", count);
	output_asm_insn(buf, NULL);
	
	output_asm_insn("mov (%1)+, (%0)+", operands);
	output_asm_insn("mov (%1)+, (%0)+", operands);
	output_asm_insn("mov (%1)+, (%0)+", operands);
	output_asm_insn("mov (%1)+, (%0)+", operands);
	
	if (TARGET_45)
	{
	    sprintf(buf, "sob %%4, movestrhi%d", count);
	    output_asm_insn(buf, operands);
	}
	else
	{
	    output_asm_insn("dec %4", operands);
	    
	    sprintf(buf, "bgt movestrhi%d", count);
	    output_asm_insn(buf, NULL);
	}
	
	count ++;
	break;
	
	;
	
    }
    
    return "";
}

/* for future use */
int
comparison_operator_index(op)
  rtx op;
{
    switch (GET_CODE(op))
    {
      case NE:
	return 0;
	
      case EQ:
	return 1;
	
      case GE:
	return 2;
	
      case GT:
	return 3;
	
      case LE:
	return 4;
	
      case LT:
	return 5;
	
      case GEU:
	return 6;
	
      case GTU:
	return 7;

      case LEU:
	return 8;
	
      case LTU:
	return 9;
	
      default:
	return -1;
    }
}    
	
/* tests whether the rtx is a comparison operator */
int
comp_operator (op, mode)
  rtx op;
  enum machine_mode mode;
{
    return comparison_operator_index(op) >= 0;
}

    
int
legitimate_address_p (mode, address)
  enum machine_mode mode;
  rtx address;
{
/* #define REG_OK_STRICT */
    GO_IF_LEGITIMATE_ADDRESS(mode, address, win);
    
    return 0;
    
  win:
    return 1;

/* #undef REG_OK_STRICT */
}