Data Structures
struct	saved_hard_reg

Typedefs
typedef void	refmarker_fn (rtx loc, enum machine_mode mode, int hardregno, void mark_arg)

Functions
static int	reg_save_code (int, enum machine_mode)
static int	reg_restore_code (int, enum machine_mode)
static void	initiate_saved_hard_regs (void)
static void	new_saved_hard_reg (int, int)
static void	finish_saved_hard_regs (void)
static int	saved_hard_reg_compare_func (const void , const void )
static void	mark_set_regs (rtx, const_rtx, void *)
static void	mark_referenced_regs (rtx , refmarker_fn mark, void *mark_arg)
static int	insert_save (struct insn_chain , int, int, HARD_REG_SET , enum machine_mode *)
static int	insert_restore (struct insn_chain , int, int, int, enum machine_mode )
static struct insn_chain *	insert_one_insn (struct insn_chain *, int, int, rtx)
static void	add_stored_regs (rtx, const_rtx, void *)
static int	reg_save_code ()
static int	reg_restore_code ()
void	init_caller_save ()
void	init_save_areas ()
static void	new_saved_hard_reg ()
static int	saved_hard_reg_compare_func ()
void	setup_save_areas ()
void	save_call_clobbered_regs ()
static void	mark_set_regs ()
static void	add_stored_regs ()
static void	mark_referenced_regs ()
static void	mark_reg_as_referenced (rtx loc, enum machine_mode mode, int hardregno, void arg)
static void	replace_reg_with_saved_mem (rtx loc, enum machine_mode mode, int regno, void arg)
static int	add_used_regs_1 ()
static void	add_used_regs ()
static struct insn_chain *	insert_one_insn ()

Variables
static rtx	regno_save_mem [FIRST_PSEUDO_REGISTER][MAX_MOVE_MAX/MIN_UNITS_PER_WORD+1]
static int	save_slots_num
static rtx	save_slots [FIRST_PSEUDO_REGISTER]
static HARD_REG_SET	hard_regs_saved
static int	n_regs_saved
static HARD_REG_SET	referenced_regs
static refmarker_fn	mark_reg_as_referenced
static refmarker_fn	replace_reg_with_saved_mem
static rtx	savepat
static rtx	restpat
static rtx	test_reg
static rtx	test_mem
static rtx	saveinsn
static rtx	restinsn
static struct saved_hard_reg *	hard_reg_map [FIRST_PSEUDO_REGISTER]
static int	saved_regs_num
static struct saved_hard_reg *	all_saved_regs [FIRST_PSEUDO_REGISTER]

Typedef Documentation

typedef void refmarker_fn(rtx *loc, enum machine_mode mode, int hardregno, void *mark_arg)

Function Documentation

static void add_stored_regs	(	rtx	,
		const_rtx	,
		void *
	)

static

static void add_stored_regs ( )

static

   Here from note_stores when an insn stores a value in a register.
   Set the proper bit or bits in the passed regset.  All pseudos that have
   been assigned hard regs have had their register number changed already,
   so we can ignore pseudos.

static void add_used_regs ( )

static

   A note_uses callback used by insert_one_insn.  Add the hard-register
   equivalent of each REG to regset DATA.

static int add_used_regs_1 ( )

static

   A for_each_rtx callback used by add_used_regs.  Add the hard-register
   equivalent of each REG to regset DATA.

static void finish_saved_hard_regs ( )

static

   Free memory allocated for the saved hard registers.

void init_caller_save ( void )

   Initialize for caller-save.

   Look at all the hard registers that are used by a call and for which
   reginfo.c has not already excluded from being used across a call.

   Ensure that we can find a mode to save the register and that there is a
   simple insn to save and restore the register.  This latter check avoids
   problems that would occur if we tried to save the MQ register of some
   machines directly into memory.

     First find all the registers that we need to deal with and all
     the modes that they can have.  If we can't find a mode to use,
     we can't have the register live over calls.

     The following code tries to approximate the conditions under which
     we can easily save and restore a register without scratch registers or
     other complexities.  It will usually work, except under conditions where
     the validity of an insn operand is dependent on the address offset.
     No such cases are currently known.

     We first find a typical offset from some BASE_REG_CLASS register.
     This address is chosen by finding the first register in the class
     and by finding the smallest power of two that is a valid offset from
     that register in every mode we will use to save registers.

     If we didn't find a valid address, we must use register indirect.

     Next we try to form an insn to save and restore the register.  We
     see if such an insn is recognized and meets its constraints.

     To avoid lots of unnecessary RTL allocation, we construct all the RTL
     once, then modify the memory and register operands in-place.

Referenced by split_live_ranges_for_shrink_wrap().

void init_save_areas ( void )

   Initialize save areas by showing that we haven't allocated any yet.

static void initiate_saved_hard_regs ( )

static

   First called function for work with saved hard registers.

Referenced by saved_hard_reg_compare_func().

static struct insn_chain* insert_one_insn	(	struct insn_chain *	,
		int	,
		int	,
		rtx
	)

staticread

Referenced by insert_restore(), replace_reg_with_saved_mem(), and save_call_clobbered_regs().

static struct insn_chain* insert_one_insn ( )

staticread

   Emit a new caller-save insn and set the code.

     If INSN references CC0, put our insns in front of the insn that sets
     CC0.  This is always safe, since the only way we could be passed an
     insn that references CC0 is for a restore, and doing a restore earlier
     isn't a problem.  We do, however, assume here that CALL_INSNs don't
     reference CC0.  Guard against non-INSN's like CODE_LABEL.

         ??? It would be nice if we could exclude the already / still saved
         registers from the live sets.

         If CHAIN->INSN is a call, then the registers which contain
         the arguments to the function are live in the new insn.

         ??? It would be nice if we could exclude the already / still saved
         registers from the live sets, and observe REG_UNUSED notes.

         Registers that are set in CHAIN->INSN live in the new insn.
         (Unless there is a REG_UNUSED note for them, but we don't
          look for them here.)

static int insert_restore	(	struct insn_chain *	chain,
		int	before_p,
		int	regno,
		int	maxrestore,
		enum machine_mode *	save_mode
	)

static

   Insert a sequence of insns to restore.  Place these insns in front of
   CHAIN if BEFORE_P is nonzero, behind the insn otherwise.  MAXRESTORE is
   the maximum number of registers which should be restored during this call.
   It should never be less than 1 since we only work with entire registers.

   Note that we have verified in init_caller_save that we can do this
   with a simple SET, so use it.  Set INSN_CODE to what we save there
   since the address might not be valid so the insn might not be recognized.
   These insns will be reloaded and have register elimination done by
   find_reload, so we need not worry about that here.

   Return the extra number of registers saved.

     A common failure mode if register status is not correct in the
     RTL is for this routine to be called with a REGNO we didn't
     expect to save.  That will cause us to write an insn with a (nil)
     SET_DEST or SET_SRC.  Instead of doing so and causing a crash
     later, check for this common case here instead.  This will remove
     one step in debugging such problems.

     Get the pattern to emit and update our status.

     See if we can restore `maxrestore' registers at once.  Work
     backwards to the single register case.

         Must do this one restore at a time.

         Check that insn to restore REGNO in save_mode[regno] is
         correct.

     Verify that the alignment of spill space is equal to or greater
     than required.

     Clear status for all registers we restored.

     Tell our callers how many extra registers we saved/restored.

References copy_rtx(), insn_chain::dead_or_set, gen_rtx_REG(), hard_regs_saved, insert_one_insn(), n_regs_saved, and reg_save_code().

static int insert_save	(	struct insn_chain *	chain,
		int	before_p,
		int	regno,
		HARD_REG_SET *	to_save,
		enum machine_mode *	save_mode
	)

static

   Like insert_restore above, but save registers instead.

     A common failure mode if register status is not correct in the
     RTL is for this routine to be called with a REGNO we didn't
     expect to save.  That will cause us to write an insn with a (nil)
     SET_DEST or SET_SRC.  Instead of doing so and causing a crash
     later, check for this common case here.  This will remove one
     step in debugging such problems.

     Get the pattern to emit and update our status.

     See if we can save several registers with a single instruction.
     Work backwards to the single register case.

         Must do this one save at a time.

         Check that insn to save REGNO in save_mode[regno] is
         correct.

     Verify that the alignment of spill space is equal to or greater
     than required.

     Set hard_regs_saved and dead_or_set for all the registers we saved.

     Tell our callers how many extra registers we saved/restored.

References bitmap_set_range(), and reg_renumber.

Referenced by save_call_clobbered_regs().

static void mark_referenced_regs	(	rtx *	,
		refmarker_fn *	mark,
		void *	mark_arg
	)

static

static void mark_referenced_regs ( )

static

   Walk X and record all referenced registers in REFERENCED_REGS.

                 If we're setting only part of a multi-word register,
                 we shall mark it as referenced, because the words
                 that are not being set should be restored.

           ??? Will we ever end up with an equiv expression in a debug
           insn, that would have required restoring a reg, or will
           reload take care of it for us?

         If this is a pseudo that did not get a hard register, scan its
         memory location, since it might involve the use of another
         register, which might be saved.

References add_to_hard_reg_set(), and referenced_regs.

static void mark_reg_as_referenced	(	rtx *	loc,
		enum machine_mode	mode,
		int	hardregno,
		void *	arg
	)

static

   Parameter function for mark_referenced_regs() that adds registers
   present in the insn and in equivalent mems and addresses to
   referenced_regs.

static void mark_set_regs	(	rtx	,
		const_rtx	,
		void *
	)

static

Referenced by save_call_clobbered_regs().

static void mark_set_regs ( )

static

   Here from note_stores, or directly from save_call_clobbered_regs, when
   an insn stores a value in a register.
   Set the proper bit or bits in this_insn_sets.  All pseudos that have
   been assigned hard regs have had their register number changed already,
   so we can ignore pseudos.

static void new_saved_hard_reg	(	int	,
		int
	)

static

static void new_saved_hard_reg ( )

static

   Allocate and return new saved hard register with given REGNO and
   CALL_FREQ.

References saved_hard_reg::call_freq.

static int reg_restore_code	(	int	,
		enum	machine_mode
	)

static

Referenced by replace_reg_with_saved_mem().

static int reg_restore_code ( )

static

   Return the INSN_CODE used to restore register REG in mode MODE.

     Populate our cache.

References offset.

static int reg_save_code	(	int	,
		enum	machine_mode
	)

static

Referenced by insert_restore(), and replace_reg_with_saved_mem().

static int reg_save_code ( )

static

   Return the INSN_CODE used to save register REG in mode MODE.

         Depending on how HARD_REGNO_MODE_OK is defined, range propagation
         might deduce here that reg >= FIRST_PSEUDO_REGISTER.  So the assert
         below silences a warning.

     Update the register number and modes of the register
     and memory operand.

     Force re-recognition of the modified insns.

     Now extract both insns and see if we can meet their
     constraints.

static void replace_reg_with_saved_mem	(	rtx *	loc,
		enum machine_mode	mode,
		int	regno,
		void *	arg
	)

static

   Parameter function for mark_referenced_regs() that replaces
   registers referenced in a debug_insn that would have been restored,
   should it be a non-debug_insn, with their save locations.

     If none of the registers in the range would need restoring, we're
     all set.

             This is gen_lowpart_if_possible(), but without validating
             the newly-formed address.

               Adjust the address so that the address-after-the-data is
               unchanged.

References copy_rtx(), insn_chain::dead_or_set, gen_rtx_REG(), hard_regs_saved, insert_one_insn(), n_regs_saved, reg_restore_code(), and reg_save_code().

void save_call_clobbered_regs ( void )

   Find the places where hard regs are live across calls and save them.

     Computed in mark_set_regs, holds all registers set by the current
     instruction.

             If some registers have been saved, see if INSN references
             any of them.  We must restore them before the insn if so.

                   Restore all registers if this is a JUMP_INSN.

                 If a saved register is set after the call, this means we no
                 longer should restore it.  This can happen when parts of a
                 multi-word pseudo do not conflict with other pseudos, so
                 IRA may allocate the same hard register for both.  One may
                 be live across the call, while the other is set
                 afterwards.

                 Use the register life information in CHAIN to compute which
                 regs are live during the call.

                 Save hard registers always in the widest mode available.

                 Look through all live pseudos, mark their hard registers
                 and choose proper mode for saving.

                 Record all registers set in this call insn.  These don't need
                 to be saved.  N.B. the call insn might set a subreg of a
                 multi-hard-reg pseudo; then the pseudo is considered live
                 during the call, but the subreg that is set isn't.

                 Compute which hard regs must be saved before this call.

                 Must recompute n_regs_saved.

             At the end of the basic block, we must restore any registers that
             remain saved.  If the last insn in the block is a JUMP_INSN, put
             the restore before the insn, otherwise, put it after the insn.

                 When adding hard reg restores after a DEBUG_INSN, move
                 all notes between last real insn and this DEBUG_INSN after
                 the DEBUG_INSN, otherwise we could get code
                 -g/-g0 differences.

References copy_rtx(), find_reg_note(), hard_regs_saved, insert_one_insn(), insert_save(), insn_chain::live_throughout, mark_set_regs(), n_regs_saved, note_stores(), reg_renumber, and regno_reg_rtx.

static int saved_hard_reg_compare_func	(	const void *	,
		const void *
	)

static

static int saved_hard_reg_compare_func ( )

static

   The function is used to sort the saved hard register structures
   according their frequency.

References find_reg_note(), initiate_saved_hard_regs(), insn_chain::insn, insn_chain::live_throughout, insn_chain::next, reload_insn_chain, and used_regs.

void setup_save_areas ( void )

   Allocate save areas for any hard registers that might need saving.
   We take a conservative approach here and look for call-clobbered hard
   registers that are assigned to pseudos that cross calls.  This may
   overestimate slightly (especially if some of these registers are later
   used as spill registers), but it should not be significant.

   For IRA we use priority coloring to decrease stack slots needed for
   saving hard registers through calls.  We build conflicts for them
   to do coloring.

   Future work:

     In the fallback case we should iterate backwards across all possible
     modes for the save, choosing the largest available one instead of
     falling back to the smallest mode immediately.  (eg TF -> DF -> SF).

     We do not try to use "move multiple" instructions that exist
     on some machines (such as the 68k moveml).  It could be a win to try
     and use them when possible.  The hard part is doing it in a way that is
     machine independent since they might be saving non-consecutive
     registers. (imagine caller-saving d0,d1,a0,a1 on the 68k)

     Find every CALL_INSN and record which hard regs are live across the
     call into HARD_REG_MAP and HARD_REGS_USED.

     Create hard reg saved regs.

         Record all registers set in this call insn.  These don't
         need to be saved.  N.B. the call insn might set a subreg
         of a multi-hard-reg pseudo; then the pseudo is considered
         live during the call, but the subreg that is set
         isn't.

         Sibcalls are considered to set the return value.

         Look through all live pseudos, mark their hard registers.

     If requested, figure out which hard regs can share save slots.

         Find saved hard register conflicts.

             Record all registers set in this call insn.  These don't
             need to be saved.  N.B. the call insn might set a subreg
             of a multi-hard-reg pseudo; then the pseudo is considered
             live during the call, but the subreg that is set
             isn't.

             Sibcalls are considered to set the return value,
             compare df-scan.c:df_get_call_refs.

             Look through all live pseudos, mark their hard registers.

         Sort saved hard regs.

         Initiate slots available from the previous reload
         iteration.

         Allocate stack slots for the saved hard registers.

         We are not sharing slots. 

         Run through all the call-used hard-registers and allocate
         space for each in the caller-save area.  Try to allocate space
         in a manner which allows multi-register saves/restores to be done.

               If no mode exists for this size, try another.  Also break out
               if we have already saved this hard register.

               See if any register in this group has been saved.

               We have found an acceptable mode to store in.  Since
               hard register is always saved in the widest mode
               available, the mode may be wider than necessary, it is
               OK to reduce the alignment of spill space.  We will
               verify that it is equal to or greater than required
               when we restore and save the hard register in
               insert_restore and insert_save.

               Setup single word save area just in case...

                 This should not depend on WORDS_BIG_ENDIAN.
                 The order of words in regs is the same as in memory.

     Now loop again and set the alias set of any save areas we made to
     the alias set used to represent frame objects.

Variable Documentation

struct saved_hard_reg* all_saved_regs[FIRST_PSEUDO_REGISTER]

static

   Pointers to all the structures.  Index is the order number of the
   corresponding structure.

struct saved_hard_reg* hard_reg_map[FIRST_PSEUDO_REGISTER]

static

   Map: hard register number to the corresponding structure.

HARD_REG_SET hard_regs_saved

static

   Set of hard regs currently residing in save area (during insn scan).

Referenced by insert_restore(), replace_reg_with_saved_mem(), and save_call_clobbered_regs().

refmarker_fn mark_reg_as_referenced

static

int n_regs_saved

static

   Number of registers currently in hard_regs_saved.

Referenced by insert_restore(), replace_reg_with_saved_mem(), and save_call_clobbered_regs().

HARD_REG_SET referenced_regs

static

   Computed by mark_referenced_regs, all regs referenced in a given
   insn.

Referenced by mark_referenced_regs().

rtx regno_save_mem[FIRST_PSEUDO_REGISTER][MAX_MOVE_MAX/MIN_UNITS_PER_WORD+1]

static

   For each hard register, a place on the stack where it can be saved,
   if needed.

refmarker_fn replace_reg_with_saved_mem

static

rtx restinsn

static

rtx restpat

static

rtx save_slots[FIRST_PSEUDO_REGISTER]

static

   Allocated slots so far.

int save_slots_num

static

   The number of elements in the subsequent array.

int saved_regs_num

static

   The number of all structures representing hard registers should be
   saved, in order words, the number of used elements in the following
   array.

rtx saveinsn

static

rtx savepat

static

rtx test_mem

static

rtx test_reg

static

Data Structures

Typedefs

Functions

Variables

Typedef Documentation

Function Documentation

Variable Documentation