c4x.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

				        gen_rtx_REG (QImode, R1_REGNO),
					GEN_INT(size & 0xffff)));
          RTX_FRAME_RELATED_P (insn) = 1;
	  insn = emit_insn (gen_addqi3 (gen_rtx_REG (QImode, SP_REGNO),
				        gen_rtx_REG (QImode, SP_REGNO),
				        gen_rtx_REG (QImode, R1_REGNO)));
          RTX_FRAME_RELATED_P (insn) = 1;
	}
      else if (size != 0)
	{
	  /* Local vars take up less than 32767 words, so we can directly
	     add the number.  */
	  insn = emit_insn (gen_addqi3 (gen_rtx_REG (QImode, SP_REGNO),
				        gen_rtx_REG (QImode, SP_REGNO),
				        GEN_INT (size)));
          RTX_FRAME_RELATED_P (insn) = 1;
	}
      
      for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
	{
	  if (regs_ever_live[regno] && ! call_used_regs[regno])
	    {
	      if (IS_FLOAT_CALL_SAVED_REGNO (regno))
		{
		  if (TARGET_PRESERVE_FLOAT)
		    {
                      insn = emit_insn (gen_pushqi
					(gen_rtx_REG (QImode, regno)));
		      RTX_FRAME_RELATED_P (insn) = 1;
		    }
                  insn = emit_insn (gen_pushqf (gen_rtx_REG (QFmode, regno)));
		  RTX_FRAME_RELATED_P (insn) = 1;
		}
	      else if ((! dont_push_ar3) || (regno != AR3_REGNO))
		{
                  insn = emit_insn (gen_pushqi ( gen_rtx_REG (QImode, regno)));
		  RTX_FRAME_RELATED_P (insn) = 1;
		}
	    }
	}
    }
}


void
c4x_expand_epilogue()
{
  int regno;
  int jump = 0;
  int dont_pop_ar3;
  rtx insn;
  int size = get_frame_size ();
  
  /* For __assembler__ function build no epilogue.  */
  if (c4x_assembler_function_p ())
    {
      insn = emit_jump_insn (gen_return_from_epilogue ());
      RTX_FRAME_RELATED_P (insn) = 1;
      return;
    }

  /* For __interrupt__ function build specific epilogue.  */
  if (c4x_interrupt_function_p ())
    {
      for (regno = FIRST_PSEUDO_REGISTER - 1; regno >= 0; --regno)
	{
	  if (! c4x_isr_reg_used_p (regno))
	    continue;
	  if (regno == DP_REGNO)
	    {
	      insn = emit_insn (gen_pop_dp ());
	      RTX_FRAME_RELATED_P (insn) = 1;
	    }
	  else
	    {
	      /* We have to use unspec because the compiler will delete insns
	         that are not call-saved.  */
	      if (IS_EXT_REGNO (regno))
		{
                  insn = emit_insn (gen_popqf_unspec
				    (gen_rtx_REG (QFmode, regno)));
	          RTX_FRAME_RELATED_P (insn) = 1;
		}
	      insn = emit_insn (gen_popqi_unspec (gen_rtx_REG (QImode, regno)));
	      RTX_FRAME_RELATED_P (insn) = 1;
	    }
	}
      if (size)
	{
	  insn = emit_insn (gen_subqi3 (gen_rtx_REG (QImode, SP_REGNO),
				        gen_rtx_REG (QImode, SP_REGNO),
					GEN_INT(size)));
          RTX_FRAME_RELATED_P (insn) = 1;
	  insn = emit_insn (gen_popqi
			    (gen_rtx_REG (QImode, AR3_REGNO)));
          RTX_FRAME_RELATED_P (insn) = 1;
	}
      insn = emit_insn (gen_pop_st ());
      RTX_FRAME_RELATED_P (insn) = 1;
      insn = emit_jump_insn (gen_return_from_interrupt_epilogue ());
      RTX_FRAME_RELATED_P (insn) = 1;
    }
  else
    {
      if (frame_pointer_needed)
	{
	  if ((size != 0) 
	      || (current_function_args_size != 0) 
	      || (optimize < 2))
	    {
	      insn = emit_insn
		(gen_movqi (gen_rtx_REG (QImode, R2_REGNO),
			    gen_rtx_MEM (QImode,
					 gen_rtx_PLUS 
					 (QImode, gen_rtx_REG (QImode,
							       AR3_REGNO),
					  GEN_INT(-1)))));
	      RTX_FRAME_RELATED_P (insn) = 1;
	      
	      /* We already have the return value and the fp,
	         so we need to add those to the stack.  */
	      size += 2;
	      jump = 1;
	      dont_pop_ar3 = 1;
	    }
	  else
	    {
	      /* Since ar3 is not used for anything, we don't need to
	         pop it.  */
	      dont_pop_ar3 = 1;
	    }
	}
      else
	{
	  dont_pop_ar3 = 0;	/* If we use ar3, we need to pop it.  */
	  if (size || current_function_args_size)
	    {
	      /* If we are ommitting the frame pointer, we still have
	         to make space for it so the offsets are correct
	         unless we don't use anything on the stack at all.  */
	      size += 1;
	    }
	}
      
      /* Now restore the saved registers, putting in the delayed branch
         where required.  */
      for (regno = FIRST_PSEUDO_REGISTER - 1; regno >= 0; regno--)
	{
	  if (regs_ever_live[regno] && ! call_used_regs[regno])
	    {
	      if (regno == AR3_REGNO && dont_pop_ar3)
		continue;
	      
	      if (IS_FLOAT_CALL_SAVED_REGNO (regno))
		{
		  insn = emit_insn (gen_popqf_unspec
				    (gen_rtx_REG (QFmode, regno)));
		  RTX_FRAME_RELATED_P (insn) = 1;
		  if (TARGET_PRESERVE_FLOAT)
		    {
                      insn = emit_insn (gen_popqi_unspec
					(gen_rtx_REG (QImode, regno)));
		      RTX_FRAME_RELATED_P (insn) = 1;
		    }
		}
	      else
		{
		  insn = emit_insn (gen_popqi (gen_rtx_REG (QImode, regno)));
		  RTX_FRAME_RELATED_P (insn) = 1;
		}
	    }
	}
      
      if (frame_pointer_needed)
	{
	  if ((size != 0)
	      || (current_function_args_size != 0)
	      || (optimize < 2))
	    {
	      /* Restore the old FP.  */
	      insn = emit_insn 
		(gen_movqi 
		 (gen_rtx_REG (QImode, AR3_REGNO),
		  gen_rtx_MEM (QImode, gen_rtx_REG (QImode, AR3_REGNO))));
	      
	      RTX_FRAME_RELATED_P (insn) = 1;
	    }
	}
      
      if (size > 32767)
	{
	  /* Local vars are too big, it will take multiple operations
	     to decrement SP.  */
	  if (TARGET_C3X)
	    {
	      insn = emit_insn (gen_movqi (gen_rtx_REG (QImode, R3_REGNO),
					   GEN_INT(size >> 16)));
              RTX_FRAME_RELATED_P (insn) = 1;
	      insn = emit_insn (gen_lshrqi3 (gen_rtx_REG (QImode, R3_REGNO),
					     gen_rtx_REG (QImode, R3_REGNO),
					     GEN_INT(-16)));
              RTX_FRAME_RELATED_P (insn) = 1;
	    }
	  else
	    {
	      insn = emit_insn (gen_movqi (gen_rtx_REG (QImode, R3_REGNO),
					   GEN_INT(size & ~0xffff)));
              RTX_FRAME_RELATED_P (insn) = 1;
	    }
	  insn = emit_insn (gen_iorqi3 (gen_rtx_REG (QImode, R3_REGNO),
				        gen_rtx_REG (QImode, R3_REGNO),
					GEN_INT(size & 0xffff)));
          RTX_FRAME_RELATED_P (insn) = 1;
	  insn = emit_insn (gen_subqi3 (gen_rtx_REG (QImode, SP_REGNO),
				        gen_rtx_REG (QImode, SP_REGNO),
				        gen_rtx_REG (QImode, R3_REGNO)));
          RTX_FRAME_RELATED_P (insn) = 1;
	}
      else if (size != 0)
	{
	  /* Local vars take up less than 32768 words, so we can directly
	     subtract the number.  */
	  insn = emit_insn (gen_subqi3 (gen_rtx_REG (QImode, SP_REGNO),
				        gen_rtx_REG (QImode, SP_REGNO),
				        GEN_INT(size)));
          RTX_FRAME_RELATED_P (insn) = 1;
	}
      
      if (jump)
	{
	  insn = emit_jump_insn (gen_return_indirect_internal
				 (gen_rtx_REG (QImode, R2_REGNO)));
          RTX_FRAME_RELATED_P (insn) = 1;
	}
      else
	{
          insn = emit_jump_insn (gen_return_from_epilogue ());
          RTX_FRAME_RELATED_P (insn) = 1;
	}
    }
}


int
c4x_null_epilogue_p ()
{
  int regno;

  if (reload_completed
      && ! c4x_assembler_function_p ()
      && ! c4x_interrupt_function_p ()
      && ! current_function_calls_alloca
      && ! current_function_args_size
      && ! (optimize < 2)
      && ! get_frame_size ())
    {
      for (regno = FIRST_PSEUDO_REGISTER - 1; regno >= 0; regno--)
	if (regs_ever_live[regno] && ! call_used_regs[regno]
	    && (regno != AR3_REGNO))
	  return 0;
      return 1;
    }
  return 0;
}


int
c4x_emit_move_sequence (operands, mode)
     rtx *operands;
     enum machine_mode mode;     
{
  rtx op0 = operands[0];
  rtx op1 = operands[1];

  if (! reload_in_progress
      && ! REG_P (op0) 
      && ! REG_P (op1)
      && ! (stik_const_operand (op1, mode) && ! push_operand (op0, mode)))
    op1 = force_reg (mode, op1);

  if (GET_CODE (op1) == LO_SUM
      && GET_MODE (op1) == Pmode
      && dp_reg_operand (XEXP (op1, 0), mode))
    {
      /* expand_increment will sometimes create a LO_SUM immediate
	 address.  */
      op1 = XEXP (op1, 1);
    }
  else if (symbolic_address_operand (op1, mode))
    {
      if (TARGET_LOAD_ADDRESS)
	{
	  /* Alias analysis seems to do a better job if we force
	     constant addresses to memory after reload.  */
	  emit_insn (gen_load_immed_address (op0, op1));
	  return 1;
	}
      else
	{
	  /* Stick symbol or label address into the constant pool.  */
	  op1 = force_const_mem (Pmode, op1);
	}
    }
  else if (mode == HFmode && CONSTANT_P (op1) && ! LEGITIMATE_CONSTANT_P (op1))
    {
      /* We could be a lot smarter about loading some of these
	 constants...  */
      op1 = force_const_mem (mode, op1);
    }

  /* Convert (MEM (SYMREF)) to a (MEM (LO_SUM (REG) (SYMREF)))
     and emit associated (HIGH (SYMREF)) if large memory model.  
     c4x_legitimize_address could be used to do this,
     perhaps by calling validize_address.  */
  if (TARGET_EXPOSE_LDP
      && ! (reload_in_progress || reload_completed)
      && GET_CODE (op1) == MEM
      && symbolic_address_operand (XEXP (op1, 0), Pmode))
    {
      rtx dp_reg = gen_rtx_REG (Pmode, DP_REGNO);
      if (! TARGET_SMALL)
	emit_insn (gen_set_ldp (dp_reg, XEXP (op1, 0)));
      op1 = change_address (op1, mode,
			    gen_rtx_LO_SUM (Pmode, dp_reg, XEXP (op1, 0)));
    }

  if (TARGET_EXPOSE_LDP
      && ! (reload_in_progress || reload_completed)
      && GET_CODE (op0) == MEM 
      && symbolic_address_operand (XEXP (op0, 0), Pmode))
    {
      rtx dp_reg = gen_rtx_REG (Pmode, DP_REGNO);
      if (! TARGET_SMALL)
	emit_insn (gen_set_ldp (dp_reg, XEXP (op0, 0)));
      op0 = change_address (op0, mode,
			    gen_rtx_LO_SUM (Pmode, dp_reg, XEXP (op0, 0)));
    }

  if (GET_CODE (op0) == SUBREG
      && mixed_subreg_operand (op0, mode))
    {
      /* We should only generate these mixed mode patterns
	 during RTL generation.  If we need do it later on
	 then we'll have to emit patterns that won't clobber CC.  */
      if (reload_in_progress || reload_completed)
	abort ();
      if (GET_MODE (SUBREG_REG (op0)) == QImode)
	op0 = SUBREG_REG (op0);
      else if (GET_MODE (SUBREG_REG (op0)) == HImode)
	{
	  op0 = copy_rtx (op0);
	  PUT_MODE (op0, QImode);
	}
      else
	abort ();

      if (mode == QFmode)
	emit_insn (gen_storeqf_int_clobber (op0, op1));
      else
	abort ();
      return 1;
    }

  if (GET_CODE (op1) == SUBREG
      && mixed_subreg_operand (op1, mode))
    {
      /* We should only generate these mixed mode patterns
	 during RTL generation.  If we need do it later on
	 then we'll have to emit patterns that won't clobber CC.  */
      if (reload_in_progress || reload_completed)
	abort ();
      if (GET_MODE (SUBREG_REG (op1)) == QImode)
	op1 = SUBREG_REG (op1);
      else if (GET_MODE (SUBREG_REG (op1)) == HImode)
	{
	  op1 = copy_rtx (op1);
	  PUT_MODE (op1, QImode);
	}
      else
	abort ();

      if (mode == QFmode)
	emit_insn (gen_loadqf_int_clobber (op0, op1));
      else
	abort ();
      return 1;
    }

  if (mode == QImode
      && reg_operand (op0, mode)
      && const_int_operand (op1, mode)
      && ! IS_INT16_CONST (INTVAL (op1))
      && ! IS_HIGH_CONST (INTVAL (op1)))
    {
      emit_insn (gen_loadqi_big_constant (op0, op1));
      return 1;
    }

  if (mode == HImode
      && reg_operand (op0, mode)
      && const_int_operand (op1, mode))
    {
      emit_insn (gen_loadhi_big_constant (op0, op1));
      return 1;
    }

  /* Adjust operands in case we have modified them.  */
  operands[0] = op0;
  operands[1] = op1;

  /* Emit normal pattern.  */
  return 0;
}


void
c4x_emit_libcall (libcall, code, dmode, smode, noperands, operands)
     rtx libcall;
     enum rtx_code code;
     enum machine_mode dmode;
     enum machine_mode smode;
     int noperands;
     rtx *operands;
{
  rtx ret;
  rtx insns;
  rtx equiv;

  start_sequence ();
  switch (noperands)
    {
    case 2:
      ret = emit_library_call_value (libcall, NULL_RTX, 1, dmode, 1,
				     operands[1], smode);
      equiv = gen_rtx (code, dmode, operands[1]);
      break;

    case 3:
      ret = emit_library_call_value (libcall, NULL_RTX, 1, dmode, 2,
				     operands[1], smode, operands[2], smode);
      equiv = gen_rtx (code, dmode, operands[1], operands[2]);
      break;

    default:
      abort ();
    }

  insns = get_insns ();
  end_sequence ();
  emit_libcall_block (insns, operands[0], ret, equiv);
}


void
c4x_emit_libcall3 (libcall, code, mode, operands)
     rtx libcall;
     enum rtx_code code;
     enum machine_mode mode;
     rtx *operands;
{
  c4x_emit_libcall (libcall, code, mode, mode, 3, operands);
}


void
c4x_emit_libcall_mulhi (libcall, code, mode, operands)
     rtx libcall;
     enum rtx_code code;
     enum machine_mode mode;
     rtx *operands;
{
  rtx ret;
  rtx insns;
  rtx equiv;

  start_sequence ();
  ret = emit_library_call_value (libcall, NULL_RTX, 1, mode, 2,
                                 operands[1], mode, operands[2], mode);
  equiv = gen_rtx_TRUNCATE (mode,