frv.c

Mac OS X 10.4.9 for x86 Source Code gcc 实现源代码

     enum machine_mode mode,	/* mode to allocate register with */
     int mark_as_used,		/* register not available after allocation */
     int no_abort)		/* return NULL instead of aborting */
{
  int regno = info->next_reg[ (int)class ];
  int orig_regno = regno;
  HARD_REG_SET *reg_in_class = &reg_class_contents[ (int)class ];
  int i, nr;

  for (;;)
    {
      if (TEST_HARD_REG_BIT (*reg_in_class, regno)
	  && TEST_HARD_REG_BIT (info->regs, regno))
	  break;

      if (++regno >= FIRST_PSEUDO_REGISTER)
	regno = 0;
      if (regno == orig_regno)
	{
	  if (no_abort)
	    return NULL_RTX;
	  else
	    abort ();
	}
    }

  nr = HARD_REGNO_NREGS (regno, mode);
  info->next_reg[ (int)class ] = regno + nr;

  if (mark_as_used)
    for (i = 0; i < nr; i++)
      CLEAR_HARD_REG_BIT (info->regs, regno+i);

  return gen_rtx_REG (mode, regno);
}


/* Return an rtx with the value OFFSET, which will either be a register or a
   signed 12-bit integer.  It can be used as the second operand in an "add"
   instruction, or as the index in a load or store.

   The function returns a constant rtx if OFFSET is small enough, otherwise
   it loads the constant into register OFFSET_REGNO and returns that.  */
static rtx
frv_frame_offset_rtx (int offset)
{
  rtx offset_rtx = GEN_INT (offset);
  if (IN_RANGE_P (offset, -2048, 2047))
    return offset_rtx;
  else
    {
      rtx reg_rtx = gen_rtx_REG (SImode, OFFSET_REGNO);
      if (IN_RANGE_P (offset, -32768, 32767))
	emit_insn (gen_movsi (reg_rtx, offset_rtx));
      else
	{
	  emit_insn (gen_movsi_high (reg_rtx, offset_rtx));
	  emit_insn (gen_movsi_lo_sum (reg_rtx, offset_rtx));
	}
      return reg_rtx;
    }
}

/* Generate (mem:MODE (plus:Pmode BASE (frv_frame_offset OFFSET)))).  The
   prologue and epilogue uses such expressions to access the stack.  */
static rtx
frv_frame_mem (enum machine_mode mode, rtx base, int offset)
{
  return gen_rtx_MEM (mode, gen_rtx_PLUS (Pmode,
					  base,
					  frv_frame_offset_rtx (offset)));
}

/* Generate a frame-related expression:

	(set REG (mem (plus (sp) (const_int OFFSET)))).

   Such expressions are used in FRAME_RELATED_EXPR notes for more complex
   instructions.  Marking the expressions as frame-related is superfluous if
   the note contains just a single set.  But if the note contains a PARALLEL
   or SEQUENCE that has several sets, each set must be individually marked
   as frame-related.  */
static rtx
frv_dwarf_store (rtx reg, int offset)
{
  rtx set = gen_rtx_SET (VOIDmode,
			 gen_rtx_MEM (GET_MODE (reg),
				      plus_constant (stack_pointer_rtx,
						     offset)),
			 reg);
  RTX_FRAME_RELATED_P (set) = 1;
  return set;
}

/* Emit a frame-related instruction whose pattern is PATTERN.  The
   instruction is the last in a sequence that cumulatively performs the
   operation described by DWARF_PATTERN.  The instruction is marked as
   frame-related and has a REG_FRAME_RELATED_EXPR note containing
   DWARF_PATTERN.  */
static void
frv_frame_insn (rtx pattern, rtx dwarf_pattern)
{
  rtx insn = emit_insn (pattern);
  RTX_FRAME_RELATED_P (insn) = 1;
  REG_NOTES (insn) = alloc_EXPR_LIST (REG_FRAME_RELATED_EXPR,
				      dwarf_pattern,
				      REG_NOTES (insn));
}

/* Emit instructions that transfer REG to or from the memory location (sp +
   STACK_OFFSET).  The register is stored in memory if ACCESSOR->OP is
   FRV_STORE and loaded if it is FRV_LOAD.  Only the prologue uses this
   function to store registers and only the epilogue uses it to load them.

   The caller sets up ACCESSOR so that BASE is equal to (sp + BASE_OFFSET).
   The generated instruction will use BASE as its base register.  BASE may
   simply be the stack pointer, but if several accesses are being made to a
   region far away from the stack pointer, it may be more efficient to set
   up a temporary instead.

   Store instructions will be frame-related and will be annotated with the
   overall effect of the store.  Load instructions will be followed by a
   (use) to prevent later optimizations from zapping them.

   The function takes care of the moves to and from SPRs, using TEMP_REGNO
   as a temporary in such cases.  */
static void
frv_frame_access (frv_frame_accessor_t *accessor, rtx reg, int stack_offset)
{
  enum machine_mode mode = GET_MODE (reg);
  rtx mem = frv_frame_mem (mode,
			   accessor->base,
			   stack_offset - accessor->base_offset);

  if (accessor->op == FRV_LOAD)
    {
      if (SPR_P (REGNO (reg)))
	{
	  rtx temp = gen_rtx_REG (mode, TEMP_REGNO);
	  emit_insn (gen_rtx_SET (VOIDmode, temp, mem));
	  emit_insn (gen_rtx_SET (VOIDmode, reg, temp));
	}
      else
	emit_insn (gen_rtx_SET (VOIDmode, reg, mem));
      emit_insn (gen_rtx_USE (VOIDmode, reg));
    }
  else
    {
      if (SPR_P (REGNO (reg)))
	{
	  rtx temp = gen_rtx_REG (mode, TEMP_REGNO);
	  emit_insn (gen_rtx_SET (VOIDmode, temp, reg));
	  frv_frame_insn (gen_rtx_SET (Pmode, mem, temp),
			  frv_dwarf_store (reg, stack_offset));
	}
      else if (GET_MODE (reg) == DImode)
	{
	  /* For DImode saves, the dwarf2 version needs to be a SEQUENCE
	     with a separate save for each register.  */
	  rtx reg1 = gen_rtx_REG (SImode, REGNO (reg));
	  rtx reg2 = gen_rtx_REG (SImode, REGNO (reg) + 1);
	  rtx set1 = frv_dwarf_store (reg1, stack_offset);
	  rtx set2 = frv_dwarf_store (reg2, stack_offset + 4);
	  frv_frame_insn (gen_rtx_SET (Pmode, mem, reg),
			  gen_rtx_PARALLEL (VOIDmode,
					    gen_rtvec (2, set1, set2)));
	}
      else
	frv_frame_insn (gen_rtx_SET (Pmode, mem, reg),
			frv_dwarf_store (reg, stack_offset));
    }
}

/* A function that uses frv_frame_access to transfer a group of registers to
   or from the stack.  ACCESSOR is passed directly to frv_frame_access, INFO
   is the stack information generated by frv_stack_info, and REG_SET is the
   number of the register set to transfer.  */
static void
frv_frame_access_multi (frv_frame_accessor_t *accessor,
                        frv_stack_t *info,
                        int reg_set)
{
  frv_stack_regs_t *regs_info;
  int regno;

  regs_info = &info->regs[reg_set];
  for (regno = regs_info->first; regno <= regs_info->last; regno++)
    if (info->save_p[regno])
      frv_frame_access (accessor,
			info->save_p[regno] == REG_SAVE_2WORDS
			? gen_rtx_REG (DImode, regno)
			: gen_rtx_REG (SImode, regno),
			info->reg_offset[regno]);
}

/* Save or restore callee-saved registers that are kept outside the frame
   header.  The function saves the registers if OP is FRV_STORE and restores
   them if OP is FRV_LOAD.  INFO is the stack information generated by
   frv_stack_info.  */
static void
frv_frame_access_standard_regs (enum frv_stack_op op, frv_stack_t *info)
{
  frv_frame_accessor_t accessor;

  accessor.op = op;
  accessor.base = stack_pointer_rtx;
  accessor.base_offset = 0;
  frv_frame_access_multi (&accessor, info, STACK_REGS_GPR);
  frv_frame_access_multi (&accessor, info, STACK_REGS_FPR);
  frv_frame_access_multi (&accessor, info, STACK_REGS_LCR);
}


/* Called after register allocation to add any instructions needed for the
   prologue.  Using a prologue insn is favored compared to putting all of the
   instructions in the TARGET_ASM_FUNCTION_PROLOGUE target hook, since
   it allows the scheduler to intermix instructions with the saves of
   the caller saved registers.  In some cases, it might be necessary
   to emit a barrier instruction as the last insn to prevent such
   scheduling.

   Also any insns generated here should have RTX_FRAME_RELATED_P(insn) = 1
   so that the debug info generation code can handle them properly.  */
void
frv_expand_prologue (void)
{
  frv_stack_t *info = frv_stack_info ();
  rtx sp = stack_pointer_rtx;
  rtx fp = frame_pointer_rtx;
  frv_frame_accessor_t accessor;

  if (TARGET_DEBUG_STACK)
    frv_debug_stack (info);

  if (info->total_size == 0)
    return;

  /* We're interested in three areas of the frame here:

         A: the register save area
	 B: the old FP
	 C: the header after B

     If the frame pointer isn't used, we'll have to set up A, B and C
     using the stack pointer.  If the frame pointer is used, we'll access
     them as follows:

         A: set up using sp
	 B: set up using sp or a temporary (see below)
	 C: set up using fp

     We set up B using the stack pointer if the frame is small enough.
     Otherwise, it's more efficient to copy the old stack pointer into a
     temporary and use that.

     Note that it's important to make sure the prologue and epilogue use the
     same registers to access A and C, since doing otherwise will confuse
     the aliasing code.  */

  /* Set up ACCESSOR for accessing region B above.  If the frame pointer
     isn't used, the same method will serve for C.  */
  accessor.op = FRV_STORE;
  if (frame_pointer_needed && info->total_size > 2048)
    {
      rtx insn;

      accessor.base = gen_rtx_REG (Pmode, OLD_SP_REGNO);
      accessor.base_offset = info->total_size;
      insn = emit_insn (gen_movsi (accessor.base, sp));
    }
  else
    {
      accessor.base = stack_pointer_rtx;
      accessor.base_offset = 0;
    }

  /* Allocate the stack space.  */
  {
    rtx asm_offset = frv_frame_offset_rtx (-info->total_size);
    rtx dwarf_offset = GEN_INT (-info->total_size);

    frv_frame_insn (gen_stack_adjust (sp, sp, asm_offset),
		    gen_rtx_SET (Pmode,
				 sp,
				 gen_rtx_PLUS (Pmode, sp, dwarf_offset)));
  }

  /* If the frame pointer is needed, store the old one at (sp + FP_OFFSET)
     and point the new one to that location.  */
  if (frame_pointer_needed)
    {
      int fp_offset = info->reg_offset[FRAME_POINTER_REGNUM];

      /* ASM_SRC and DWARF_SRC both point to the frame header.  ASM_SRC is
	 based on ACCESSOR.BASE but DWARF_SRC is always based on the stack
	 pointer.  */
      rtx asm_src = plus_constant (accessor.base,
				   fp_offset - accessor.base_offset);
      rtx dwarf_src = plus_constant (sp, fp_offset);

      /* Store the old frame pointer at (sp + FP_OFFSET).  */
      frv_frame_access (&accessor, fp, fp_offset);

      /* Set up the new frame pointer.  */
      frv_frame_insn (gen_rtx_SET (VOIDmode, fp, asm_src),
		      gen_rtx_SET (VOIDmode, fp, dwarf_src));

      /* Access region C from the frame pointer.  */
      accessor.base = fp;
      accessor.base_offset = fp_offset;
    }

  /* Set up region C.  */
  frv_frame_access_multi (&accessor, info, STACK_REGS_STRUCT);
  frv_frame_access_multi (&accessor, info, STACK_REGS_LR);
  frv_frame_access_multi (&accessor, info, STACK_REGS_STDARG);

  /* Set up region A.  */
  frv_frame_access_standard_regs (FRV_STORE, info);

  /* If this is a varargs/stdarg function, issue a blockage to prevent the
     scheduler from moving loads before the stores saving the registers.  */
  if (info->stdarg_size > 0)
    emit_insn (gen_blockage ());

  /* Set up pic register/small data register for this function.  */
  if (!TARGET_FDPIC && flag_pic && cfun->uses_pic_offset_table)
    emit_insn (gen_pic_prologue (gen_rtx_REG (Pmode, PIC_REGNO),
				 gen_rtx_REG (Pmode, LR_REGNO),
				 gen_rtx_REG (SImode, OFFSET_REGNO)));
}


/* Under frv, all of the work is done via frv_expand_epilogue, but
   this function provides a convenient place to do cleanup.  */

static void
frv_function_epilogue (FILE *file ATTRIBUTE_UNUSED,
                       HOST_WIDE_INT size ATTRIBUTE_UNUSED)
{
  frv_stack_cache = (frv_stack_t *)0;

  /* Zap last used registers for conditional execution.  */
  memset (&frv_ifcvt.tmp_reg, 0, sizeof (frv_ifcvt.tmp_reg));

  /* Release the bitmap of created insns.  */
  BITMAP_FREE (frv_ifcvt.scratch_insns_bitmap);
}


/* Called after register allocation to add any instructions needed for the
   epilogue.  Using an epilogue insn is favored compared to putting all of the
   instructions in the TARGET_ASM_FUNCTION_PROLOGUE target hook, since
   it allows the scheduler to intermix instructions with the saves of
   the caller saved registers.  In some cases, it might be necessary
   to emit a barrier instruction as the last insn to prevent such
   scheduling.  */

void
frv_expand_epilogue (bool emit_return)
{
  frv_stack_t *info = frv_stack_info ();
  rtx fp = frame_pointer_rtx;
  rtx sp = stack_pointer_rtx;
  rtx return_addr;
  int fp_offset;

  fp_offset = info->reg_offset[FRAME_POINTER_REGNUM];

  /* Restore the stack pointer to its original value if alloca or the like
     is used.  */
  if (! current_function_sp_is_unchanging)
    emit_insn (gen_addsi3 (sp, fp, frv_frame_offset_rtx (-fp_offset)));

  /* Restore the callee-saved registers that were used in this function.  */
  frv_frame_access_standard_regs (FRV_LOAD, info);

  /* Set RETURN_ADDR to the address we should return to.  Set it to NULL if
     no return instruction should be emitted.  */
  if (info->sav