1 /* Subroutines for manipulating rtx's in semantically interesting ways.
2 Copyright (C) 1987, 1991 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
26 #include "hard-reg-set.h"
27 #include "insn-config.h"
29 #include "insn-flags.h"
30 #include "insn-codes.h"
32 /* Return an rtx for the sum of X and the integer C.
34 This function should be used via the `plus_constant' macro. */
37 plus_constant_wide (x, c)
39 register HOST_WIDE_INT c;
41 register RTX_CODE code;
42 register enum machine_mode mode;
56 return GEN_INT (INTVAL (x) + c);
60 HOST_WIDE_INT l1 = CONST_DOUBLE_LOW (x);
61 HOST_WIDE_INT h1 = CONST_DOUBLE_HIGH (x);
63 HOST_WIDE_INT h2 = c < 0 ? ~0 : 0;
66 add_double (l1, h1, l2, h2, &lv, &hv);
68 return immed_double_const (lv, hv, VOIDmode);
72 /* If this is a reference to the constant pool, try replacing it with
73 a reference to a new constant. If the resulting address isn't
74 valid, don't return it because we have no way to validize it. */
75 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
76 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
79 = force_const_mem (GET_MODE (x),
80 plus_constant (get_pool_constant (XEXP (x, 0)),
82 if (memory_address_p (GET_MODE (tem), XEXP (tem, 0)))
88 /* If adding to something entirely constant, set a flag
89 so that we can add a CONST around the result. */
100 /* The interesting case is adding the integer to a sum.
101 Look for constant term in the sum and combine
102 with C. For an integer constant term, we make a combined
103 integer. For a constant term that is not an explicit integer,
104 we cannot really combine, but group them together anyway.
106 Use a recursive call in case the remaining operand is something
107 that we handle specially, such as a SYMBOL_REF. */
109 if (GET_CODE (XEXP (x, 1)) == CONST_INT)
110 return plus_constant (XEXP (x, 0), c + INTVAL (XEXP (x, 1)));
111 else if (CONSTANT_P (XEXP (x, 0)))
112 return gen_rtx (PLUS, mode,
113 plus_constant (XEXP (x, 0), c),
115 else if (CONSTANT_P (XEXP (x, 1)))
116 return gen_rtx (PLUS, mode,
118 plus_constant (XEXP (x, 1), c));
122 x = gen_rtx (PLUS, mode, x, GEN_INT (c));
124 if (GET_CODE (x) == SYMBOL_REF || GET_CODE (x) == LABEL_REF)
126 else if (all_constant)
127 return gen_rtx (CONST, mode, x);
132 /* This is the same as `plus_constant', except that it handles LO_SUM.
134 This function should be used via the `plus_constant_for_output' macro. */
137 plus_constant_for_output_wide (x, c)
139 register HOST_WIDE_INT c;
141 register RTX_CODE code = GET_CODE (x);
142 register enum machine_mode mode = GET_MODE (x);
143 int all_constant = 0;
145 if (GET_CODE (x) == LO_SUM)
146 return gen_rtx (LO_SUM, mode, XEXP (x, 0),
147 plus_constant_for_output (XEXP (x, 1), c));
150 return plus_constant (x, c);
153 /* If X is a sum, return a new sum like X but lacking any constant terms.
154 Add all the removed constant terms into *CONSTPTR.
155 X itself is not altered. The result != X if and only if
156 it is not isomorphic to X. */
159 eliminate_constant_term (x, constptr)
166 if (GET_CODE (x) != PLUS)
169 /* First handle constants appearing at this level explicitly. */
170 if (GET_CODE (XEXP (x, 1)) == CONST_INT
171 && 0 != (tem = simplify_binary_operation (PLUS, GET_MODE (x), *constptr,
173 && GET_CODE (tem) == CONST_INT)
176 return eliminate_constant_term (XEXP (x, 0), constptr);
180 x0 = eliminate_constant_term (XEXP (x, 0), &tem);
181 x1 = eliminate_constant_term (XEXP (x, 1), &tem);
182 if ((x1 != XEXP (x, 1) || x0 != XEXP (x, 0))
183 && 0 != (tem = simplify_binary_operation (PLUS, GET_MODE (x),
185 && GET_CODE (tem) == CONST_INT)
188 return gen_rtx (PLUS, GET_MODE (x), x0, x1);
194 /* Returns the insn that next references REG after INSN, or 0
195 if REG is clobbered before next referenced or we cannot find
196 an insn that references REG in a straight-line piece of code. */
199 find_next_ref (reg, insn)
205 for (insn = NEXT_INSN (insn); insn; insn = next)
207 next = NEXT_INSN (insn);
208 if (GET_CODE (insn) == NOTE)
210 if (GET_CODE (insn) == CODE_LABEL
211 || GET_CODE (insn) == BARRIER)
213 if (GET_CODE (insn) == INSN
214 || GET_CODE (insn) == JUMP_INSN
215 || GET_CODE (insn) == CALL_INSN)
217 if (reg_set_p (reg, insn))
219 if (reg_mentioned_p (reg, PATTERN (insn)))
221 if (GET_CODE (insn) == JUMP_INSN)
223 if (simplejump_p (insn))
224 next = JUMP_LABEL (insn);
228 if (GET_CODE (insn) == CALL_INSN
229 && REGNO (reg) < FIRST_PSEUDO_REGISTER
230 && call_used_regs[REGNO (reg)])
239 /* Return an rtx for the size in bytes of the value of EXP. */
245 tree size = size_in_bytes (TREE_TYPE (exp));
247 if (TREE_CODE (size) != INTEGER_CST
248 && contains_placeholder_p (size))
249 size = build (WITH_RECORD_EXPR, sizetype, size, exp);
251 return expand_expr (size, NULL_RTX, TYPE_MODE (sizetype), 0);
254 /* Return a copy of X in which all memory references
255 and all constants that involve symbol refs
256 have been replaced with new temporary registers.
257 Also emit code to load the memory locations and constants
258 into those registers.
260 If X contains no such constants or memory references,
261 X itself (not a copy) is returned.
263 If a constant is found in the address that is not a legitimate constant
264 in an insn, it is left alone in the hope that it might be valid in the
267 X may contain no arithmetic except addition, subtraction and multiplication.
268 Values returned by expand_expr with 1 for sum_ok fit this constraint. */
271 break_out_memory_refs (x)
274 if (GET_CODE (x) == MEM
275 || (CONSTANT_P (x) && CONSTANT_ADDRESS_P (x)
276 && GET_MODE (x) != VOIDmode))
278 register rtx temp = force_reg (GET_MODE (x), x);
279 mark_reg_pointer (temp);
282 else if (GET_CODE (x) == PLUS || GET_CODE (x) == MINUS
283 || GET_CODE (x) == MULT)
285 register rtx op0 = break_out_memory_refs (XEXP (x, 0));
286 register rtx op1 = break_out_memory_refs (XEXP (x, 1));
287 if (op0 != XEXP (x, 0) || op1 != XEXP (x, 1))
288 x = gen_rtx (GET_CODE (x), Pmode, op0, op1);
293 /* Given a memory address or facsimile X, construct a new address,
294 currently equivalent, that is stable: future stores won't change it.
296 X must be composed of constants, register and memory references
297 combined with addition, subtraction and multiplication:
298 in other words, just what you can get from expand_expr if sum_ok is 1.
300 Works by making copies of all regs and memory locations used
301 by X and combining them the same way X does.
302 You could also stabilize the reference to this address
303 by copying the address to a register with copy_to_reg;
304 but then you wouldn't get indexed addressing in the reference. */
310 if (GET_CODE (x) == REG)
312 if (REGNO (x) != FRAME_POINTER_REGNUM
313 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
314 && REGNO (x) != HARD_FRAME_POINTER_REGNUM
319 else if (GET_CODE (x) == MEM)
321 else if (GET_CODE (x) == PLUS || GET_CODE (x) == MINUS
322 || GET_CODE (x) == MULT)
324 register rtx op0 = copy_all_regs (XEXP (x, 0));
325 register rtx op1 = copy_all_regs (XEXP (x, 1));
326 if (op0 != XEXP (x, 0) || op1 != XEXP (x, 1))
327 x = gen_rtx (GET_CODE (x), Pmode, op0, op1);
332 /* Return something equivalent to X but valid as a memory address
333 for something of mode MODE. When X is not itself valid, this
334 works by copying X or subexpressions of it into registers. */
337 memory_address (mode, x)
338 enum machine_mode mode;
343 /* By passing constant addresses thru registers
344 we get a chance to cse them. */
345 if (! cse_not_expected && CONSTANT_P (x) && CONSTANT_ADDRESS_P (x))
346 return force_reg (Pmode, x);
348 /* Accept a QUEUED that refers to a REG
349 even though that isn't a valid address.
350 On attempting to put this in an insn we will call protect_from_queue
351 which will turn it into a REG, which is valid. */
352 if (GET_CODE (x) == QUEUED
353 && GET_CODE (QUEUED_VAR (x)) == REG)
356 /* We get better cse by rejecting indirect addressing at this stage.
357 Let the combiner create indirect addresses where appropriate.
358 For now, generate the code so that the subexpressions useful to share
359 are visible. But not if cse won't be done! */
361 if (! cse_not_expected && GET_CODE (x) != REG)
362 x = break_out_memory_refs (x);
364 /* At this point, any valid address is accepted. */
365 GO_IF_LEGITIMATE_ADDRESS (mode, x, win);
367 /* If it was valid before but breaking out memory refs invalidated it,
368 use it the old way. */
369 if (memory_address_p (mode, oldx))
372 /* Perform machine-dependent transformations on X
373 in certain cases. This is not necessary since the code
374 below can handle all possible cases, but machine-dependent
375 transformations can make better code. */
376 LEGITIMIZE_ADDRESS (x, oldx, mode, win);
378 /* PLUS and MULT can appear in special ways
379 as the result of attempts to make an address usable for indexing.
380 Usually they are dealt with by calling force_operand, below.
381 But a sum containing constant terms is special
382 if removing them makes the sum a valid address:
383 then we generate that address in a register
384 and index off of it. We do this because it often makes
385 shorter code, and because the addresses thus generated
386 in registers often become common subexpressions. */
387 if (GET_CODE (x) == PLUS)
389 rtx constant_term = const0_rtx;
390 rtx y = eliminate_constant_term (x, &constant_term);
391 if (constant_term == const0_rtx
392 || ! memory_address_p (mode, y))
393 return force_operand (x, NULL_RTX);
395 y = gen_rtx (PLUS, GET_MODE (x), copy_to_reg (y), constant_term);
396 if (! memory_address_p (mode, y))
397 return force_operand (x, NULL_RTX);
400 if (GET_CODE (x) == MULT || GET_CODE (x) == MINUS)
401 return force_operand (x, NULL_RTX);
403 /* If we have a register that's an invalid address,
404 it must be a hard reg of the wrong class. Copy it to a pseudo. */
405 if (GET_CODE (x) == REG)
406 return copy_to_reg (x);
408 /* Last resort: copy the value to a register, since
409 the register is a valid address. */
410 return force_reg (Pmode, x);
415 if (flag_force_addr && ! cse_not_expected && GET_CODE (x) != REG
416 /* Don't copy an addr via a reg if it is one of our stack slots. */
417 && ! (GET_CODE (x) == PLUS
418 && (XEXP (x, 0) == virtual_stack_vars_rtx
419 || XEXP (x, 0) == virtual_incoming_args_rtx)))
421 if (general_operand (x, Pmode))
422 return force_reg (Pmode, x);
424 return force_operand (x, NULL_RTX);
429 /* Like `memory_address' but pretend `flag_force_addr' is 0. */
432 memory_address_noforce (mode, x)
433 enum machine_mode mode;
436 int ambient_force_addr = flag_force_addr;
440 val = memory_address (mode, x);
441 flag_force_addr = ambient_force_addr;
445 /* Convert a mem ref into one with a valid memory address.
446 Pass through anything else unchanged. */
452 if (GET_CODE (ref) != MEM)
454 if (memory_address_p (GET_MODE (ref), XEXP (ref, 0)))
456 /* Don't alter REF itself, since that is probably a stack slot. */
457 return change_address (ref, GET_MODE (ref), XEXP (ref, 0));
460 /* Return a modified copy of X with its memory address copied
461 into a temporary register to protect it from side effects.
462 If X is not a MEM, it is returned unchanged (and not copied).
463 Perhaps even if it is a MEM, if there is no need to change it. */
470 if (GET_CODE (x) != MEM)
473 if (rtx_unstable_p (addr))
475 rtx temp = copy_all_regs (addr);
477 if (GET_CODE (temp) != REG)
478 temp = copy_to_reg (temp);
479 mem = gen_rtx (MEM, GET_MODE (x), temp);
481 /* Mark returned memref with in_struct if it's in an array or
482 structure. Copy const and volatile from original memref. */
484 MEM_IN_STRUCT_P (mem) = MEM_IN_STRUCT_P (x) || GET_CODE (addr) == PLUS;
485 RTX_UNCHANGING_P (mem) = RTX_UNCHANGING_P (x);
486 MEM_VOLATILE_P (mem) = MEM_VOLATILE_P (x);
492 /* Copy the value or contents of X to a new temp reg and return that reg. */
498 register rtx temp = gen_reg_rtx (GET_MODE (x));
500 /* If not an operand, must be an address with PLUS and MULT so
501 do the computation. */
502 if (! general_operand (x, VOIDmode))
503 x = force_operand (x, temp);
506 emit_move_insn (temp, x);
511 /* Like copy_to_reg but always give the new register mode Pmode
512 in case X is a constant. */
518 return copy_to_mode_reg (Pmode, x);
521 /* Like copy_to_reg but always give the new register mode MODE
522 in case X is a constant. */
525 copy_to_mode_reg (mode, x)
526 enum machine_mode mode;
529 register rtx temp = gen_reg_rtx (mode);
531 /* If not an operand, must be an address with PLUS and MULT so
532 do the computation. */
533 if (! general_operand (x, VOIDmode))
534 x = force_operand (x, temp);
536 if (GET_MODE (x) != mode && GET_MODE (x) != VOIDmode)
539 emit_move_insn (temp, x);
543 /* Load X into a register if it is not already one.
544 Use mode MODE for the register.
545 X should be valid for mode MODE, but it may be a constant which
546 is valid for all integer modes; that's why caller must specify MODE.
548 The caller must not alter the value in the register we return,
549 since we mark it as a "constant" register. */
553 enum machine_mode mode;
556 register rtx temp, insn;
558 if (GET_CODE (x) == REG)
560 temp = gen_reg_rtx (mode);
561 insn = emit_move_insn (temp, x);
562 /* Let optimizers know that TEMP's value never changes
563 and that X can be substituted for it. */
566 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
571 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_EQUAL, x, REG_NOTES (insn));
576 /* If X is a memory ref, copy its contents to a new temp reg and return
577 that reg. Otherwise, return X. */
584 if (GET_CODE (x) != MEM || GET_MODE (x) == BLKmode)
586 temp = gen_reg_rtx (GET_MODE (x));
587 emit_move_insn (temp, x);
591 /* Copy X to TARGET (if it's nonzero and a reg)
592 or to a new temp reg and return that reg.
593 MODE is the mode to use for X in case it is a constant. */
596 copy_to_suggested_reg (x, target, mode)
598 enum machine_mode mode;
602 if (target && GET_CODE (target) == REG)
605 temp = gen_reg_rtx (mode);
607 emit_move_insn (temp, x);
611 /* Adjust the stack pointer by ADJUST (an rtx for a number of bytes).
612 This pops when ADJUST is positive. ADJUST need not be constant. */
615 adjust_stack (adjust)
619 adjust = protect_from_queue (adjust, 0);
621 if (adjust == const0_rtx)
624 temp = expand_binop (Pmode,
625 #ifdef STACK_GROWS_DOWNWARD
630 stack_pointer_rtx, adjust, stack_pointer_rtx, 0,
633 if (temp != stack_pointer_rtx)
634 emit_move_insn (stack_pointer_rtx, temp);
637 /* Adjust the stack pointer by minus ADJUST (an rtx for a number of bytes).
638 This pushes when ADJUST is positive. ADJUST need not be constant. */
641 anti_adjust_stack (adjust)
645 adjust = protect_from_queue (adjust, 0);
647 if (adjust == const0_rtx)
650 temp = expand_binop (Pmode,
651 #ifdef STACK_GROWS_DOWNWARD
656 stack_pointer_rtx, adjust, stack_pointer_rtx, 0,
659 if (temp != stack_pointer_rtx)
660 emit_move_insn (stack_pointer_rtx, temp);
663 /* Round the size of a block to be pushed up to the boundary required
664 by this machine. SIZE is the desired size, which need not be constant. */
670 #ifdef STACK_BOUNDARY
671 int align = STACK_BOUNDARY / BITS_PER_UNIT;
674 if (GET_CODE (size) == CONST_INT)
676 int new = (INTVAL (size) + align - 1) / align * align;
677 if (INTVAL (size) != new)
678 size = GEN_INT (new);
682 size = expand_divmod (0, CEIL_DIV_EXPR, Pmode, size, GEN_INT (align),
684 size = expand_mult (Pmode, size, GEN_INT (align), NULL_RTX, 1);
686 #endif /* STACK_BOUNDARY */
690 /* Save the stack pointer for the purpose in SAVE_LEVEL. PSAVE is a pointer
691 to a previously-created save area. If no save area has been allocated,
692 this function will allocate one. If a save area is specified, it
693 must be of the proper mode.
695 The insns are emitted after insn AFTER, if nonzero, otherwise the insns
696 are emitted at the current position. */
699 emit_stack_save (save_level, psave, after)
700 enum save_level save_level;
705 /* The default is that we use a move insn and save in a Pmode object. */
706 rtx (*fcn) () = gen_move_insn;
707 enum machine_mode mode = Pmode;
709 /* See if this machine has anything special to do for this kind of save. */
712 #ifdef HAVE_save_stack_block
714 if (HAVE_save_stack_block)
716 fcn = gen_save_stack_block;
717 mode = insn_operand_mode[CODE_FOR_save_stack_block][0];
721 #ifdef HAVE_save_stack_function
723 if (HAVE_save_stack_function)
725 fcn = gen_save_stack_function;
726 mode = insn_operand_mode[CODE_FOR_save_stack_function][0];
730 #ifdef HAVE_save_stack_nonlocal
732 if (HAVE_save_stack_nonlocal)
734 fcn = gen_save_stack_nonlocal;
735 mode = insn_operand_mode[(int) CODE_FOR_save_stack_nonlocal][0];
741 /* If there is no save area and we have to allocate one, do so. Otherwise
742 verify the save area is the proper mode. */
746 if (mode != VOIDmode)
748 if (save_level == SAVE_NONLOCAL)
749 *psave = sa = assign_stack_local (mode, GET_MODE_SIZE (mode), 0);
751 *psave = sa = gen_reg_rtx (mode);
756 if (mode == VOIDmode || GET_MODE (sa) != mode)
765 /* We must validize inside the sequence, to ensure that any instructions
766 created by the validize call also get moved to the right place. */
768 sa = validize_mem (sa);
769 emit_insn (fcn (sa, stack_pointer_rtx));
770 seq = gen_sequence ();
772 emit_insn_after (seq, after);
777 sa = validize_mem (sa);
778 emit_insn (fcn (sa, stack_pointer_rtx));
782 /* Restore the stack pointer for the purpose in SAVE_LEVEL. SA is the save
783 area made by emit_stack_save. If it is zero, we have nothing to do.
785 Put any emitted insns after insn AFTER, if nonzero, otherwise at
789 emit_stack_restore (save_level, sa, after)
790 enum save_level save_level;
794 /* The default is that we use a move insn. */
795 rtx (*fcn) () = gen_move_insn;
797 /* See if this machine has anything special to do for this kind of save. */
800 #ifdef HAVE_restore_stack_block
802 if (HAVE_restore_stack_block)
803 fcn = gen_restore_stack_block;
806 #ifdef HAVE_restore_stack_function
808 if (HAVE_restore_stack_function)
809 fcn = gen_restore_stack_function;
812 #ifdef HAVE_restore_stack_nonlocal
815 if (HAVE_restore_stack_nonlocal)
816 fcn = gen_restore_stack_nonlocal;
822 sa = validize_mem (sa);
829 emit_insn (fcn (stack_pointer_rtx, sa));
830 seq = gen_sequence ();
832 emit_insn_after (seq, after);
835 emit_insn (fcn (stack_pointer_rtx, sa));
838 /* Return an rtx representing the address of an area of memory dynamically
839 pushed on the stack. This region of memory is always aligned to
840 a multiple of BIGGEST_ALIGNMENT.
842 Any required stack pointer alignment is preserved.
844 SIZE is an rtx representing the size of the area.
845 TARGET is a place in which the address can be placed.
847 KNOWN_ALIGN is the alignment (in bits) that we know SIZE has. */
850 allocate_dynamic_stack_space (size, target, known_align)
855 /* Ensure the size is in the proper mode. */
856 if (GET_MODE (size) != VOIDmode && GET_MODE (size) != Pmode)
857 size = convert_to_mode (Pmode, size, 1);
859 /* We will need to ensure that the address we return is aligned to
860 BIGGEST_ALIGNMENT. If STACK_DYNAMIC_OFFSET is defined, we don't
861 always know its final value at this point in the compilation (it
862 might depend on the size of the outgoing parameter lists, for
863 example), so we must align the value to be returned in that case.
864 (Note that STACK_DYNAMIC_OFFSET will have a default non-zero value if
865 STACK_POINTER_OFFSET or ACCUMULATE_OUTGOING_ARGS are defined).
866 We must also do an alignment operation on the returned value if
867 the stack pointer alignment is less strict that BIGGEST_ALIGNMENT.
869 If we have to align, we must leave space in SIZE for the hole
870 that might result from the alignment operation. */
872 #if defined (STACK_DYNAMIC_OFFSET) || defined(STACK_POINTER_OFFSET) || defined (ALLOCATE_OUTGOING_ARGS)
876 #if ! defined (MUST_ALIGN) && (!defined(STACK_BOUNDARY) || STACK_BOUNDARY < BIGGEST_ALIGNMENT)
882 #if 0 /* It turns out we must always make extra space, if MUST_ALIGN
883 because we must always round the address up at the end,
884 because we don't know whether the dynamic offset
885 will mess up the desired alignment. */
886 /* If we have to round the address up regardless of known_align,
887 make extra space regardless, also. */
888 if (known_align % BIGGEST_ALIGNMENT != 0)
891 if (GET_CODE (size) == CONST_INT)
892 size = GEN_INT (INTVAL (size)
893 + (BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1));
895 size = expand_binop (Pmode, add_optab, size,
896 GEN_INT (BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1),
897 NULL_RTX, 1, OPTAB_LIB_WIDEN);
902 #ifdef SETJMP_VIA_SAVE_AREA
903 /* If setjmp restores regs from a save area in the stack frame,
904 avoid clobbering the reg save area. Note that the offset of
905 virtual_incoming_args_rtx includes the preallocated stack args space.
906 It would be no problem to clobber that, but it's on the wrong side
907 of the old save area. */
910 = expand_binop (Pmode, sub_optab, virtual_stack_dynamic_rtx,
911 stack_pointer_rtx, NULL_RTX, 1, OPTAB_LIB_WIDEN);
912 size = expand_binop (Pmode, add_optab, size, dynamic_offset,
913 NULL_RTX, 1, OPTAB_LIB_WIDEN);
915 #endif /* SETJMP_VIA_SAVE_AREA */
917 /* Round the size to a multiple of the required stack alignment.
918 Since the stack if presumed to be rounded before this allocation,
919 this will maintain the required alignment.
921 If the stack grows downward, we could save an insn by subtracting
922 SIZE from the stack pointer and then aligning the stack pointer.
923 The problem with this is that the stack pointer may be unaligned
924 between the execution of the subtraction and alignment insns and
925 some machines do not allow this. Even on those that do, some
926 signal handlers malfunction if a signal should occur between those
927 insns. Since this is an extremely rare event, we have no reliable
928 way of knowing which systems have this problem. So we avoid even
929 momentarily mis-aligning the stack. */
931 #ifdef STACK_BOUNDARY
932 /* If we added a variable amount to SIZE,
933 we can no longer assume it is aligned. */
934 #if !defined (SETJMP_VIA_SAVE_AREA) && !defined (MUST_ALIGN)
935 if (known_align % STACK_BOUNDARY != 0)
937 size = round_push (size);
940 do_pending_stack_adjust ();
942 /* Don't use a TARGET that isn't a pseudo. */
943 if (target == 0 || GET_CODE (target) != REG
944 || REGNO (target) < FIRST_PSEUDO_REGISTER)
945 target = gen_reg_rtx (Pmode);
947 mark_reg_pointer (target);
949 #ifndef STACK_GROWS_DOWNWARD
950 emit_move_insn (target, virtual_stack_dynamic_rtx);
953 /* Perform the required allocation from the stack. Some systems do
954 this differently than simply incrementing/decrementing from the
956 #ifdef HAVE_allocate_stack
957 if (HAVE_allocate_stack)
959 enum machine_mode mode
960 = insn_operand_mode[(int) CODE_FOR_allocate_stack][0];
962 if (insn_operand_predicate[(int) CODE_FOR_allocate_stack][0]
963 && ! ((*insn_operand_predicate[(int) CODE_FOR_allocate_stack][0])
965 size = copy_to_mode_reg (mode, size);
967 emit_insn (gen_allocate_stack (size));
971 anti_adjust_stack (size);
973 #ifdef STACK_GROWS_DOWNWARD
974 emit_move_insn (target, virtual_stack_dynamic_rtx);
978 #if 0 /* Even if we know the stack pointer has enough alignment,
979 there's no way to tell whether virtual_stack_dynamic_rtx shares that
980 alignment, so we still need to round the address up. */
981 if (known_align % BIGGEST_ALIGNMENT != 0)
984 target = expand_divmod (0, CEIL_DIV_EXPR, Pmode, target,
985 GEN_INT (BIGGEST_ALIGNMENT / BITS_PER_UNIT),
988 target = expand_mult (Pmode, target,
989 GEN_INT (BIGGEST_ALIGNMENT / BITS_PER_UNIT),
994 /* Some systems require a particular insn to refer to the stack
995 to make the pages exist. */
998 emit_insn (gen_probe ());
1004 /* Return an rtx representing the register or memory location
1005 in which a scalar value of data type VALTYPE
1006 was returned by a function call to function FUNC.
1007 FUNC is a FUNCTION_DECL node if the precise function is known,
1011 hard_function_value (valtype, func)
1015 return FUNCTION_VALUE (valtype, func);
1018 /* Return an rtx representing the register or memory location
1019 in which a scalar value of mode MODE was returned by a library call. */
1022 hard_libcall_value (mode)
1023 enum machine_mode mode;
1025 return LIBCALL_VALUE (mode);
1028 /* Look up the tree code for a given rtx code
1029 to provide the arithmetic operation for REAL_ARITHMETIC.
1030 The function returns an int because the caller may not know
1031 what `enum tree_code' means. */
1034 rtx_to_tree_code (code)
1037 enum tree_code tcode;
1060 tcode = LAST_AND_UNUSED_TREE_CODE;
1063 return ((int) tcode);