| blob | 52b5fc3ddbb49e530f2ff380ccf69f2c99c47491 |
1 /* Convert function calls to rtl insns, for GNU C compiler.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
3 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
20 02111-1307, USA. */
41 /* Decide whether a function's arguments should be processed
42 from first to last or from last to first.
44 They should if the stack and args grow in opposite directions, but
45 only if we have push insns. */
47 #ifdef PUSH_ROUNDING
49 #ifndef PUSH_ARGS_REVERSED
50 #if defined (STACK_GROWS_DOWNWARD) != defined (ARGS_GROW_DOWNWARD)
51 #define PUSH_ARGS_REVERSED PUSH_ARGS
52 #endif
53 #endif
55 #endif
57 #ifndef PUSH_ARGS_REVERSED
58 #define PUSH_ARGS_REVERSED 0
59 #endif
61 #ifndef STACK_POINTER_OFFSET
62 #define STACK_POINTER_OFFSET 0
63 #endif
65 /* Like PREFERRED_STACK_BOUNDARY but in units of bytes, not bits. */
66 #define STACK_BYTES (PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT)
68 /* Data structure and subroutines used within expand_call. */
70 struct arg_data
71 {
72 /* Tree node for this argument. */
73 tree tree_value;
74 /* Mode for value; TYPE_MODE unless promoted. */
76 /* Current RTL value for argument, or 0 if it isn't precomputed. */
77 rtx value;
78 /* Initially-compute RTL value for argument; only for const functions. */
79 rtx initial_value;
80 /* Register to pass this argument in, 0 if passed on stack, or an
81 PARALLEL if the arg is to be copied into multiple non-contiguous
82 registers. */
83 rtx reg;
84 /* Register to pass this argument in when generating tail call sequence.
85 This is not the same register as for normal calls on machines with
86 register windows. */
87 rtx tail_call_reg;
88 /* If REG was promoted from the actual mode of the argument expression,
89 indicates whether the promotion is sign- or zero-extended. */
91 /* Number of registers to use. 0 means put the whole arg in registers.
92 Also 0 if not passed in registers. */
94 /* Nonzero if argument must be passed on stack.
95 Note that some arguments may be passed on the stack
96 even though pass_on_stack is zero, just because FUNCTION_ARG says so.
97 pass_on_stack identifies arguments that *cannot* go in registers. */
99 /* Offset of this argument from beginning of stack-args. */
101 /* Similar, but offset to the start of the stack slot. Different from
102 OFFSET if this arg pads downward. */
104 /* Size of this argument on the stack, rounded up for any padding it gets,
105 parts of the argument passed in registers do not count.
106 If REG_PARM_STACK_SPACE is defined, then register parms
107 are counted here as well. */
109 /* Location on the stack at which parameter should be stored. The store
110 has already been done if STACK == VALUE. */
111 rtx stack;
112 /* Location on the stack of the start of this argument slot. This can
113 differ from STACK if this arg pads downward. This location is known
114 to be aligned to FUNCTION_ARG_BOUNDARY. */
115 rtx stack_slot;
116 /* Place that this stack area has been saved, if needed. */
117 rtx save_area;
118 /* If an argument's alignment does not permit direct copying into registers,
119 copy in smaller-sized pieces into pseudos. These are stored in a
120 block pointed to by this field. The next field says how many
121 word-sized pseudos we made. */
124 /* The amount that the stack pointer needs to be adjusted to
125 force alignment for the next argument. */
127 };
129 /* A vector of one char per byte of stack space. A byte if nonzero if
130 the corresponding stack location has been used.
131 This vector is used to prevent a function call within an argument from
132 clobbering any stack already set up. */
135 /* Size of STACK_USAGE_MAP. */
138 /* A bitmap of virtual-incoming stack space. Bit is set if the corresponding
139 stack location's tail call argument has been already stored into the stack.
140 This bitmap is used to prevent sibling call optimization if function tries
141 to use parent's incoming argument slots when they have been already
142 overwritten with tail call arguments. */
145 /* stack_arg_under_construction is nonzero when an argument may be
146 initialized with a constructor call (including a C function that
147 returns a BLKmode struct) and expand_call must take special action
148 to make sure the object being constructed does not overlap the
149 argument list for the constructor call. */
158 CUMULATIVE_ARGS *));
178 CUMULATIVE_ARGS *,
198 static int combine_pending_stack_adjustment_and_call
201 #ifdef REG_PARM_STACK_SPACE
204 #endif
205 \f
206 /* If WHICH is 1, return 1 if EXP contains a call to the built-in function
207 `alloca'.
209 If WHICH is 0, return 1 if EXP contains a call to any function.
210 Actually, we only need return 1 if evaluating EXP would require pushing
211 arguments on the stack, but that is too difficult to compute, so we just
212 assume any function call might require the stack. */
216 static int
218 tree exp;
220 {
227 }
229 /* Recursive function to do the work of above function. */
231 static int
233 tree exp;
235 {
241 /* If this code is language-specific, we don't know what it will do. */
246 {
252 && (TYPE_RETURNS_STACK_DEPRESSED
266 {
267 tree tem;
272 }
282 calls_function_save_exprs);
287 {
288 tree local;
289 tree subblock;
297 subblock;
301 }
312 }
314 /* Only expressions, references, and blocks can contain calls. */
324 }
325 \f
326 /* Force FUNEXP into a form suitable for the address of a CALL,
327 and return that as an rtx. Also load the static chain register
328 if FNDECL is a nested function.
330 CALL_FUSAGE points to a variable holding the prospective
331 CALL_INSN_FUNCTION_USAGE information. */
333 rtx
335 rtx funexp;
336 tree fndecl;
340 {
346 /* Get possible static chain value for nested function in C. */
349 /* Make a valid memory address and copy constants thru pseudo-regs,
350 but not for a constant address if -fno-function-cse. */
352 /* If we are using registers for parameters, force the
353 function address into a register now. */
358 {
359 #ifndef NO_FUNCTION_CSE
361 #ifdef NO_RECURSIVE_FUNCTION_CSE
363 #endif
365 #endif
366 }
369 {
374 }
377 }
379 /* Generate instructions to call function FUNEXP,
380 and optionally pop the results.
381 The CALL_INSN is the first insn generated.
383 FNDECL is the declaration node of the function. This is given to the
384 macro RETURN_POPS_ARGS to determine whether this function pops its own args.
386 FUNTYPE is the data type of the function. This is given to the macro
387 RETURN_POPS_ARGS to determine whether this function pops its own args.
388 We used to allow an identifier for library functions, but that doesn't
389 work when the return type is an aggregate type and the calling convention
390 says that the pointer to this aggregate is to be popped by the callee.
392 STACK_SIZE is the number of bytes of arguments on the stack,
393 ROUNDED_STACK_SIZE is that number rounded up to
394 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
395 both to put into the call insn and to generate explicit popping
396 code if necessary.
398 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
399 It is zero if this call doesn't want a structure value.
401 NEXT_ARG_REG is the rtx that results from executing
402 FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1)
403 just after all the args have had their registers assigned.
404 This could be whatever you like, but normally it is the first
405 arg-register beyond those used for args in this call,
406 or 0 if all the arg-registers are used in this call.
407 It is passed on to `gen_call' so you can put this info in the call insn.
409 VALREG is a hard register in which a value is returned,
410 or 0 if the call does not return a value.
412 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
413 the args to this call were processed.
414 We restore `inhibit_defer_pop' to that value.
416 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
417 denote registers used by the called function. */
419 static void
423 rtx funexp;
424 tree fndecl ATTRIBUTE_UNUSED;
425 tree funtype ATTRIBUTE_UNUSED;
426 HOST_WIDE_INT stack_size ATTRIBUTE_UNUSED;
427 HOST_WIDE_INT rounded_stack_size;
428 HOST_WIDE_INT struct_value_size ATTRIBUTE_UNUSED;
429 rtx next_arg_reg ATTRIBUTE_UNUSED;
430 rtx valreg;
432 rtx call_fusage;
435 {
437 rtx call_insn;
440 #if defined (HAVE_call) && defined (HAVE_call_value)
441 rtx struct_value_size_rtx;
443 #endif
445 #ifdef CALL_POPS_ARGS
447 #endif
449 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
450 and we don't want to load it into a register as an optimization,
451 because prepare_call_address already did it if it should be done. */
455 #if defined (HAVE_sibcall_pop) && defined (HAVE_sibcall_value_pop)
459 {
461 rtx pat;
463 /* If this subroutine pops its own args, record that in the call insn
464 if possible, for the sake of frame pointer elimination. */
470 n_pop);
471 else
477 }
478 else
479 #endif
481 #if defined (HAVE_call_pop) && defined (HAVE_call_value_pop)
482 /* If the target has "call" or "call_value" insns, then prefer them
483 if no arguments are actually popped. If the target does not have
484 "call" or "call_value" insns, then we must use the popping versions
485 even if the call has no arguments to pop. */
486 #if defined (HAVE_call) && defined (HAVE_call_value)
489 #else
491 #endif
492 {
494 rtx pat;
496 /* If this subroutine pops its own args, record that in the call insn
497 if possible, for the sake of frame pointer elimination. */
503 else
509 }
510 else
511 #endif
513 #if defined (HAVE_sibcall) && defined (HAVE_sibcall_value)
516 {
520 rounded_stack_size_rtx,
522 else
525 struct_value_size_rtx));
526 }
527 else
528 #endif
530 #if defined (HAVE_call) && defined (HAVE_call_value)
532 {
537 NULL_RTX));
538 else
541 struct_value_size_rtx));
542 }
543 else
544 #endif
547 /* Find the CALL insn we just emitted. */
551 ;
556 /* Mark memory as used for "pure" function call. */
558 call_fusage
559 = gen_rtx_EXPR_LIST
563 call_fusage);
565 /* Put the register usage information on the CALL. If there is already
566 some usage information, put ours at the end. */
568 {
569 rtx link;
573 ;
576 }
577 else
580 /* If this is a const call, then set the insn's unchanging bit. */
584 /* If this call can't throw, attach a REG_EH_REGION reg note to that
585 effect. */
598 {
602 }
606 /* Restore this now, so that we do defer pops for this call's args
607 if the context of the call as a whole permits. */
611 {
620 }
623 {
624 /* If returning from the subroutine does not automatically pop the args,
625 we need an instruction to pop them sooner or later.
626 Perhaps do it now; perhaps just record how much space to pop later.
628 If returning from the subroutine does pop the args, indicate that the
629 stack pointer will be changed. */
632 {
634 /* Just pretend we did the pop. */
639 else
641 }
642 }
643 /* When we accumulate outgoing args, we must avoid any stack manipulations.
644 Restore the stack pointer to its original value now. Usually
645 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
646 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
647 popping variants of functions exist as well.
649 ??? We may optimize similar to defer_pop above, but it is
650 probably not worthwhile.
652 ??? It will be worthwhile to enable combine_stack_adjustments even for
653 such machines. */
656 }
658 /* Determine if the function identified by NAME and FNDECL is one with
659 special properties we wish to know about.
661 For example, if the function might return more than one time (setjmp), then
662 set RETURNS_TWICE to a nonzero value.
664 Similarly set LONGJMP for if the function is in the longjmp family.
666 Set MALLOC for any of the standard memory allocation functions which
667 allocate from the heap.
669 Set MAY_BE_ALLOCA for any memory allocation function that might allocate
670 space from the stack such as alloca. */
672 static int
674 tree fndecl;
676 {
680 /* Exclude functions not at the file scope, or not `extern',
681 since they are not the magic functions we would otherwise
682 think they are. */
684 {
688 /* We assume that alloca will always be called by name. It
689 makes no sense to pass it as a pointer-to-function to
690 anything that does not understand its behavior. */
699 /* Disregard prefix _, __ or __x. */
701 {
706 else
708 }
711 {
724 }
737 /* Linux specific: __clone. check NAME to insist on the
738 leading underscores, to avoid polluting the ISO / POSIX
739 namespace. */
749 /* Do not add any more malloc-like functions to this list,
750 instead mark them as malloc functions using the malloc attribute.
751 Note, realloc is not suitable for attribute malloc since
752 it may return the same address across multiple calls.
753 C++ operator new is not suitable because it is not required
754 to return a unique pointer; indeed, the standard placement new
755 just returns its argument. */
761 }
763 }
765 /* Return nonzero when tree represent call to longjmp. */
767 int
769 tree fndecl;
770 {
772 }
774 /* Return true when exp contains alloca call. */
775 bool
777 tree exp;
778 {
787 }
789 /* Detect flags (function attributes) from the function decl or type node. */
791 int
793 tree exp;
794 {
797 /* ??? We can't set IS_MALLOC for function types? */
799 {
802 /* The function exp may have the `malloc' attribute. */
806 /* The function exp may have the `pure' attribute. */
812 }
820 /* Mark if the function returns with the stack pointer depressed. We
821 cannot consider it pure or constant in that case. */
823 {
826 }
829 }
831 /* Precompute all register parameters as described by ARGS, storing values
832 into fields within the ARGS array.
834 NUM_ACTUALS indicates the total number elements in the ARGS array.
836 Set REG_PARM_SEEN if we encounter a register parameter. */
838 static void
843 {
850 {
854 {
861 /* ANSI doesn't require a sequence point here,
862 but PCC has one, so this will avoid some problems. */
864 }
866 /* If the value is a non-legitimate constant, force it into a
867 pseudo now. TLS symbols sometimes need a call to resolve. */
872 /* If we are to promote the function arg to a wider mode,
873 do it now. */
881 /* If the value is expensive, and we are inside an appropriately
882 short loop, put the value into a pseudo and then put the pseudo
883 into the hard reg.
885 For small register classes, also do this if this call uses
886 register parameters. This is to avoid reload conflicts while
887 loading the parameters registers. */
897 }
898 }
900 #ifdef REG_PARM_STACK_SPACE
902 /* The argument list is the property of the called routine and it
903 may clobber it. If the fixed area has been used for previous
904 parameters, we must save and restore it. */
906 static rtx
910 rtx argblock;
913 {
917 /* Compute the boundary of the that needs to be saved, if any. */
918 #ifdef ARGS_GROW_DOWNWARD
920 #else
922 #endif
923 {
932 }
935 {
937 enum machine_mode save_mode
939 rtx stack_area;
941 /* If we don't have the required alignment, must do this in BLKmode. */
946 #ifdef ARGS_GROW_DOWNWARD
947 stack_area
952 #else
957 #endif
961 {
965 }
966 else
967 {
970 }
971 }
974 }
976 static void
978 rtx save_area;
979 rtx argblock;
982 {
984 #ifdef ARGS_GROW_DOWNWARD
985 rtx stack_area
990 #else
991 rtx stack_area
995 low_to_save)));
996 #endif
1000 else
1003 BLOCK_OP_CALL_PARM);
1004 }
1007 /* If any elements in ARGS refer to parameters that are to be passed in
1008 registers, but not in memory, and whose alignment does not permit a
1009 direct copy into registers. Copy the values into a group of pseudos
1010 which we will later copy into the appropriate hard registers.
1012 Pseudos for each unaligned argument will be stored into the array
1013 args[argnum].aligned_regs. The caller is responsible for deallocating
1014 the aligned_regs array if it is nonzero. */
1016 static void
1020 {
1028 {
1039 /* Structures smaller than a word are aligned to the least
1040 significant byte (to the right). On a BYTES_BIG_ENDIAN machine,
1041 this means we must skip the empty high order bytes when
1042 calculating the bit offset. */
1048 {
1055 /* There is no need to restrict this code to loading items
1056 in TYPE_ALIGN sized hunks. The bitfield instructions can
1057 load up entire word sized registers efficiently.
1059 ??? This may not be needed anymore.
1060 We use to emit a clobber here but that doesn't let later
1061 passes optimize the instructions we emit. By storing 0 into
1062 the register later passes know the first AND to zero out the
1063 bitfield being set in the register is unnecessary. The store
1064 of 0 will be deleted as will at least the first AND. */
1072 BITS_PER_WORD),
1073 BITS_PER_WORD);
1074 }
1075 }
1076 }
1078 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
1079 ACTPARMS.
1081 NUM_ACTUALS is the total number of parameters.
1083 N_NAMED_ARGS is the total number of named arguments.
1085 FNDECL is the tree code for the target of this call (if known)
1087 ARGS_SO_FAR holds state needed by the target to know where to place
1088 the next argument.
1090 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
1091 for arguments which are passed in registers.
1093 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
1094 and may be modified by this routine.
1096 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
1097 flags which may may be modified by this routine. */
1099 static void
1104 ecf_flags)
1109 tree actparms;
1110 tree fndecl;
1117 {
1118 /* 1 if scanning parms front to back, -1 if scanning back to front. */
1121 /* Count arg position in order args appear. */
1126 tree p;
1131 /* In this loop, we consider args in the order they are written.
1132 We fill up ARGS from the front or from the back if necessary
1133 so that in any case the first arg to be pushed ends up at the front. */
1136 {
1138 /* In this case, must reverse order of args
1139 so that we compute and push the last arg first. */
1140 }
1141 else
1142 {
1144 }
1146 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1148 {
1155 /* Replace erroneous argument with constant zero. */
1159 /* If TYPE is a transparent union, pass things the way we would
1160 pass the first field of the union. We have already verified that
1161 the modes are the same. */
1165 /* Decide where to pass this arg.
1167 args[i].reg is nonzero if all or part is passed in registers.
1169 args[i].partial is nonzero if part but not all is passed in registers,
1170 and the exact value says how many words are passed in registers.
1172 args[i].pass_on_stack is nonzero if the argument must at least be
1173 computed on the stack. It may then be loaded back into registers
1174 if args[i].reg is nonzero.
1176 These decisions are driven by the FUNCTION_... macros and must agree
1177 with those made by function.c. */
1179 /* See if this argument should be passed by invisible reference. */
1183 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
1186 #endif
1187 )
1188 {
1189 /* If we're compiling a thunk, pass through invisible
1190 references instead of making a copy. */
1192 #ifdef FUNCTION_ARG_CALLEE_COPIES
1195 /* If it's in a register, we must make a copy of it too. */
1196 /* ??? Is this a sufficient test? Is there a better one? */
1200 #endif
1201 )
1202 {
1203 /* C++ uses a TARGET_EXPR to indicate that we want to make a
1204 new object from the argument. If we are passing by
1205 invisible reference, the callee will do that for us, so we
1206 can strip off the TARGET_EXPR. This is not always safe,
1207 but it is safe in the only case where this is a useful
1208 optimization; namely, when the argument is a plain object.
1209 In that case, the frontend is just asking the backend to
1210 make a bitwise copy of the argument. */
1221 }
1223 {
1224 /* In the V3 C++ ABI, parameters are destroyed in the caller.
1225 We implement this by passing the address of the temporary
1226 rather than expanding it into another allocated slot. */
1231 }
1232 else
1233 {
1234 /* We make a copy of the object and pass the address to the
1235 function being called. */
1236 rtx copy;
1242 STACK_CHECK_MAX_VAR_SIZE))))
1243 {
1244 /* This is a variable-sized object. Make space on the stack
1245 for it. */
1249 {
1253 }
1256 allocate_dynamic_stack_space
1259 }
1260 else
1270 }
1271 }
1276 #ifdef PROMOTE_FUNCTION_ARGS
1278 #endif
1285 #ifdef FUNCTION_INCOMING_ARG
1286 /* If this is a sibling call and the machine has register windows, the
1287 register window has to be unwinded before calling the routine, so
1288 arguments have to go into the incoming registers. */
1291 #else
1293 #endif
1295 #ifdef FUNCTION_ARG_PARTIAL_NREGS
1300 #endif
1304 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1305 it means that we are to pass this arg in the register(s) designated
1306 by the PARALLEL, but also to pass it in the stack. */
1311 /* If this is an addressable type, we must preallocate the stack
1312 since we must evaluate the object into its final location.
1314 If this is to be passed in both registers and the stack, it is simpler
1315 to preallocate. */
1320 /* If this is an addressable type, we cannot pre-evaluate it. Thus,
1321 we cannot consider this function call constant. */
1325 /* Compute the stack-size of this argument. */
1330 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1332 #else
1334 #endif
1338 #ifndef ARGS_GROW_DOWNWARD
1340 #endif
1344 /* If a part of the arg was put into registers,
1345 don't include that part in the amount pushed. */
1351 /* Update ARGS_SIZE, the total stack space for args so far. */
1355 {
1357 }
1359 /* Since the slot offset points to the bottom of the slot,
1360 we must record it after incrementing if the args grow down. */
1361 #ifdef ARGS_GROW_DOWNWARD
1367 #endif
1369 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1370 have been used, etc. */
1374 }
1375 }
1377 /* Update ARGS_SIZE to contain the total size for the argument block.
1378 Return the original constant component of the argument block's size.
1380 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1381 for arguments passed in registers. */
1383 static int
1385 preferred_stack_boundary)
1389 {
1392 /* For accumulate outgoing args mode we don't need to align, since the frame
1393 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1394 backends from generating misaligned frame sizes. */
1398 /* Compute the actual size of the argument block required. The variable
1399 and constant sizes must be combined, the size may have to be rounded,
1400 and there may be a minimum required size. */
1403 {
1409 {
1410 /* We don't handle this case yet. To handle it correctly we have
1411 to add the delta, round and subtract the delta.
1412 Currently no machine description requires this support. */
1416 }
1419 {
1420 args_size->var
1424 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1425 /* The area corresponding to register parameters is not to count in
1426 the size of the block we need. So make the adjustment. */
1427 args_size->var
1430 #endif
1431 }
1432 }
1433 else
1434 {
1439 + stack_pointer_delta
1441 / preferred_stack_boundary
1446 reg_parm_stack_space);
1448 #ifdef MAYBE_REG_PARM_STACK_SPACE
1451 #endif
1453 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1455 #endif
1456 }
1458 }
1460 /* Precompute parameters as needed for a function call.
1462 FLAGS is mask of ECF_* constants.
1464 NUM_ACTUALS is the number of arguments.
1466 ARGS is an array containing information for each argument; this
1467 routine fills in the INITIAL_VALUE and VALUE fields for each
1468 precomputed argument. */
1470 static void
1475 {
1478 /* If this function call is cse'able, precompute all the parameters.
1479 Note that if the parameter is constructed into a temporary, this will
1480 cause an additional copy because the parameter will be constructed
1481 into a temporary location and then copied into the outgoing arguments.
1482 If a parameter contains a call to alloca and this function uses the
1483 stack, precompute the parameter. */
1485 /* If we preallocated the stack space, and some arguments must be passed
1486 on the stack, then we must precompute any parameter which contains a
1487 function call which will store arguments on the stack.
1488 Otherwise, evaluating the parameter may clobber previous parameters
1489 which have already been stored into the stack. (we have code to avoid
1490 such case by saving the outgoing stack arguments, but it results in
1491 worse code) */
1496 {
1499 /* If this is an addressable type, we cannot pre-evaluate it. */
1506 /* ANSI doesn't require a sequence point here,
1507 but PCC has one, so this will avoid some problems. */
1515 {
1519 #ifdef PROMOTE_FOR_CALL_ONLY
1520 /* CSE will replace this only if it contains args[i].value
1521 pseudo, so convert it down to the declared mode using
1522 a SUBREG. */
1525 {
1531 }
1532 #endif
1533 }
1534 }
1535 }
1537 /* Given the current state of MUST_PREALLOCATE and information about
1538 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1539 compute and return the final value for MUST_PREALLOCATE. */
1541 static int
1547 {
1548 /* See if we have or want to preallocate stack space.
1550 If we would have to push a partially-in-regs parm
1551 before other stack parms, preallocate stack space instead.
1553 If the size of some parm is not a multiple of the required stack
1554 alignment, we must preallocate.
1556 If the total size of arguments that would otherwise create a copy in
1557 a temporary (such as a CALL) is more than half the total argument list
1558 size, preallocation is faster.
1560 Another reason to preallocate is if we have a machine (like the m88k)
1561 where stack alignment is required to be maintained between every
1562 pair of insns, not just when the call is made. However, we assume here
1563 that such machines either do not have push insns (and hence preallocation
1564 would occur anyway) or the problem is taken care of with
1565 PUSH_ROUNDING. */
1568 {
1574 {
1585 copy_to_evaluate_size
1587 }
1592 }
1594 }
1596 /* If we preallocated stack space, compute the address of each argument
1597 and store it into the ARGS array.
1599 We need not ensure it is a valid memory address here; it will be
1600 validized when it is used.
1602 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1604 static void
1607 rtx argblock;
1609 {
1611 {
1619 {
1622 rtx addr;
1624 /* Skip this parm if it will not be passed on the stack. */
1630 else
1640 else
1648 /* Function incoming arguments may overlap with sibling call
1649 outgoing arguments and we cannot allow reordering of reads
1650 from function arguments with stores to outgoing arguments
1651 of sibling calls. */
1654 }
1655 }
1656 }
1658 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1659 in a call instruction.
1661 FNDECL is the tree node for the target function. For an indirect call
1662 FNDECL will be NULL_TREE.
1664 EXP is the CALL_EXPR for this call. */
1666 static rtx
1668 tree fndecl;
1669 tree exp;
1670 {
1671 rtx funexp;
1673 /* Get the function to call, in the form of RTL. */
1675 {
1676 /* If this is the first use of the function, see if we need to
1677 make an external definition for it. */
1679 {
1682 }
1684 /* Get a SYMBOL_REF rtx for the function address. */
1686 }
1687 else
1688 /* Generate an rtx (probably a pseudo-register) for the address. */
1689 {
1694 }
1696 }
1698 /* Do the register loads required for any wholly-register parms or any
1699 parms which are passed both on the stack and in a register. Their
1700 expressions were already evaluated.
1702 Mark all register-parms as living through the call, putting these USE
1703 insns in the CALL_INSN_FUNCTION_USAGE field.
1705 When IS_SIBCALL, perform the check_sibcall_overlap_argument_overlap
1706 checking, setting *SIBCALL_FAILURE if appropriate. */
1708 static void
1717 {
1720 #ifdef LOAD_ARGS_REVERSED
1722 #else
1724 #endif
1725 {
1732 {
1734 /* Set to non-negative if must move a word at a time, even if just
1735 one word (e.g, partial == 1 && mode == DFmode). Set to -1 if
1736 we just use a normal move insn. This value can be zero if the
1737 argument is a zero size structure with no fields. */
1744 /* Handle calls that pass values in multiple non-contiguous
1745 locations. The Irix 6 ABI has examples of this. */
1751 /* If simple case, just do move. If normal partial, store_one_arg
1752 has already loaded the register for us. In all other cases,
1753 load the register(s) from memory. */
1758 /* If we have pre-computed the values to put in the registers in
1759 the case of non-aligned structures, copy them in now. */
1771 /* When a parameter is a block, and perhaps in other cases, it is
1772 possible that it did a load from an argument slot that was
1773 already clobbered. */
1778 /* Handle calls that pass values in multiple non-contiguous
1779 locations. The Irix 6 ABI has examples of this. */
1784 else
1786 }
1787 }
1788 }
1790 /* Try to integrate function. See expand_inline_function for documentation
1791 about the parameters. */
1793 static rtx
1795 tree fndecl;
1796 tree actparms;
1797 rtx target;
1799 tree type;
1800 rtx structure_value_addr;
1801 {
1802 rtx temp;
1803 rtx before_call;
1808 #ifdef REG_PARM_STACK_SPACE
1809 #ifdef MAYBE_REG_PARM_STACK_SPACE
1811 #else
1813 #endif
1814 #endif
1822 structure_value_addr);
1826 /* If inlining succeeded, return. */
1828 {
1830 {
1831 /* If the outgoing argument list must be preserved, push
1832 the stack before executing the inlined function if it
1833 makes any calls. */
1840 {
1841 rtx first_insn
1845 /* Look for a call in the inline function code.
1846 If DECL_SAVED_INSNS (fndecl)->outgoing_args_size is
1847 nonzero then there is a call and it is not necessary
1848 to scan the insns. */
1856 {
1857 /* Reserve enough stack space so that the largest
1858 argument list of any function call in the inline
1859 function does not overlap the argument list being
1860 evaluated. This is usually an overestimate because
1861 allocate_dynamic_stack_space reserves space for an
1862 outgoing argument list in addition to the requested
1863 space, but there is no way to ask for stack space such
1864 that an argument list of a certain length can be
1865 safely constructed.
1867 Add the stack space reserved for register arguments, if
1868 any, in the inline function. What is really needed is the
1869 largest value of reg_parm_stack_space in the inline
1870 function, but that is not available. Using the current
1871 value of reg_parm_stack_space is wrong, but gives
1872 correct results on all supported machines. */
1885 }
1886 }
1887 }
1889 /* If the result is equivalent to TARGET, return TARGET to simplify
1890 checks in store_expr. They can be equivalent but not equal in the
1891 case of a function that returns BLKmode. */
1895 }
1897 /* If inlining failed, mark FNDECL as needing to be compiled
1898 separately after all. If function was declared inline,
1899 give a warning. */
1902 {
1905 }
1908 }
1910 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
1911 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
1912 bytes, then we would need to push some additional bytes to pad the
1913 arguments. So, we compute an adjust to the stack pointer for an
1914 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
1915 bytes. Then, when the arguments are pushed the stack will be perfectly
1916 aligned. ARGS_SIZE->CONSTANT is set to the number of bytes that should
1917 be popped after the call. Returns the adjustment. */
1919 static int
1921 args_size,
1922 preferred_unit_stack_boundary)
1926 {
1927 /* The number of bytes to pop so that the stack will be
1928 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
1929 HOST_WIDE_INT adjustment;
1930 /* The alignment of the stack after the arguments are pushed, if we
1931 just pushed the arguments without adjust the stack here. */
1932 HOST_WIDE_INT unadjusted_alignment;
1934 unadjusted_alignment
1938 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
1939 as possible -- leaving just enough left to cancel out the
1940 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
1941 PENDING_STACK_ADJUST is non-negative, and congruent to
1942 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
1944 /* Begin by trying to pop all the bytes. */
1945 unadjusted_alignment
1946 = (unadjusted_alignment
1949 /* Push enough additional bytes that the stack will be aligned
1950 after the arguments are pushed. */
1952 {
1955 else
1957 }
1959 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
1960 bytes after the call. The right number is the entire
1961 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
1962 by the arguments in the first place. */
1963 args_size->constant
1967 }
1969 /* Scan X expression if it does not dereference any argument slots
1970 we already clobbered by tail call arguments (as noted in stored_args_map
1971 bitmap).
1972 Return nonzero if X expression dereferences such argument slots,
1973 zero otherwise. */
1975 static int
1977 rtx x;
1978 {
1979 RTX_CODE code;
1990 {
1995 current_function_internal_arg_pointer
1998 else
2001 #ifdef ARGS_GROW_DOWNWARD
2003 #endif
2011 }
2013 /* Scan all subexpressions. */
2016 {
2018 {
2021 }
2023 {
2027 }
2028 }
2030 }
2032 /* Scan sequence after INSN if it does not dereference any argument slots
2033 we already clobbered by tail call arguments (as noted in stored_args_map
2034 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
2035 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
2036 should be 0). Return nonzero if sequence after INSN dereferences such argument
2037 slots, zero otherwise. */
2039 static int
2041 rtx insn;
2044 {
2049 else
2058 {
2059 #ifdef ARGS_GROW_DOWNWARD
2061 #else
2063 #endif
2067 }
2069 }
2071 /* Generate all the code for a function call
2072 and return an rtx for its value.
2073 Store the value in TARGET (specified as an rtx) if convenient.
2074 If the value is stored in TARGET then TARGET is returned.
2075 If IGNORE is nonzero, then we ignore the value of the function call. */
2077 rtx
2079 tree exp;
2080 rtx target;
2082 {
2083 /* Nonzero if we are currently expanding a call. */
2086 /* List of actual parameters. */
2088 /* RTX for the function to be called. */
2089 rtx funexp;
2090 /* Sequence of insns to perform a tail recursive "call". */
2092 /* Sequence of insns to perform a normal "call". */
2094 /* Sequence of insns to perform a tail recursive "call". */
2096 /* Data type of the function. */
2097 tree funtype;
2098 /* Declaration of the function being called,
2099 or 0 if the function is computed (not known by name). */
2101 rtx insn;
2106 /* Register in which non-BLKmode value will be returned,
2107 or 0 if no value or if value is BLKmode. */
2108 rtx valreg;
2109 /* Address where we should return a BLKmode value;
2110 0 if value not BLKmode. */
2112 /* Nonzero if that address is being passed by treating it as
2113 an extra, implicit first parameter. Otherwise,
2114 it is passed by being copied directly into struct_value_rtx. */
2116 /* Size of aggregate value wanted, or zero if none wanted
2117 or if we are using the non-reentrant PCC calling convention
2118 or expecting the value in registers. */
2120 /* Nonzero if called function returns an aggregate in memory PCC style,
2121 by returning the address of where to find it. */
2124 /* Number of actual parameters in this call, including struct value addr. */
2126 /* Number of named args. Args after this are anonymous ones
2127 and they must all go on the stack. */
2130 /* Vector of information about each argument.
2131 Arguments are numbered in the order they will be pushed,
2132 not the order they are written. */
2135 /* Total size in bytes of all the stack-parms scanned so far. */
2138 /* Size of arguments before any adjustments (such as rounding). */
2140 /* Data on reg parms scanned so far. */
2141 CUMULATIVE_ARGS args_so_far;
2142 /* Nonzero if a reg parm has been scanned. */
2144 /* Nonzero if this is an indirect function call. */
2146 /* Nonzero if we must avoid push-insns in the args for this call.
2147 If stack space is allocated for register parameters, but not by the
2148 caller, then it is preallocated in the fixed part of the stack frame.
2149 So the entire argument block must then be preallocated (i.e., we
2150 ignore PUSH_ROUNDING in that case). */
2154 /* Size of the stack reserved for parameter registers. */
2157 /* Address of space preallocated for stack parms
2158 (on machines that lack push insns), or 0 if space not preallocated. */
2161 /* Mask of ECF_ flags. */
2163 /* Nonzero if this is a call to an inline function. */
2165 #ifdef REG_PARM_STACK_SPACE
2166 /* Define the boundary of the register parm stack space that needs to be
2167 save, if any. */
2170 #endif
2180 rtx call_fusage;
2183 /* The alignment of the stack, in bits. */
2184 HOST_WIDE_INT preferred_stack_boundary;
2185 /* The alignment of the stack, in bytes. */
2186 HOST_WIDE_INT preferred_unit_stack_boundary;
2188 /* See if this is "nothrow" function call. */
2192 /* See if we can find a DECL-node for the actual function.
2193 As a result, decide whether this is a call to an integrable function. */
2197 {
2205 {
2206 /* In case this function later becomes inlinable,
2207 record that there was already a non-inline call to it.
2209 Use abstraction instead of setting TREE_ADDRESSABLE
2210 directly. */
2213 {
2216 }
2218 }
2221 }
2223 /* If we don't have specific function to call, see if we have a
2224 attributes set in the type. */
2225 else
2228 #ifdef REG_PARM_STACK_SPACE
2229 #ifdef MAYBE_REG_PARM_STACK_SPACE
2231 #else
2233 #endif
2234 #endif
2236 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2239 #endif
2241 /* Warn if this value is an aggregate type,
2242 regardless of which calling convention we are using for it. */
2246 /* Set up a place to return a structure. */
2248 /* Cater to broken compilers. */
2250 {
2251 /* This call returns a big structure. */
2254 #ifdef PCC_STATIC_STRUCT_RETURN
2255 {
2257 /* Easier than making that case work right. */
2259 {
2260 /* In case this is a static function, note that it has been
2261 used. */
2265 }
2266 }
2268 {
2272 {
2273 /* The structure value address arg is already in actparms.
2274 Pull it out. It might be nice to just leave it there, but
2275 we need to set structure_value_addr. */
2280 }
2283 else
2284 {
2285 /* For variable-sized objects, we must be called with a target
2286 specified. If we were to allocate space on the stack here,
2287 we would have no way of knowing when to free it. */
2293 }
2294 }
2296 }
2298 /* If called function is inline, try to integrate it. */
2301 {
2304 structure_value_addr);
2307 }
2309 /* Figure out the amount to which the stack should be aligned. */
2312 /* Operand 0 is a pointer-to-function; get the type of the function. */
2318 /* See if this is a call to a function that can return more than once
2319 or a call to longjmp or malloc. */
2325 /* If struct_value_rtx is 0, it means pass the address
2326 as if it were an extra parameter. */
2328 {
2329 /* If structure_value_addr is a REG other than
2330 virtual_outgoing_args_rtx, we can use always use it. If it
2331 is not a REG, we must always copy it into a register.
2332 If it is virtual_outgoing_args_rtx, we must copy it to another
2333 register in some cases. */
2335 || (ACCUMULATE_OUTGOING_ARGS
2336 && stack_arg_under_construction
2341 actparms
2344 temp),
2345 actparms);
2347 }
2349 /* Count the arguments and set NUM_ACTUALS. */
2351 num_actuals++;
2353 /* Compute number of named args.
2354 Normally, don't include the last named arg if anonymous args follow.
2355 We do include the last named arg if STRICT_ARGUMENT_NAMING is nonzero.
2356 (If no anonymous args follow, the result of list_length is actually
2357 one too large. This is harmless.)
2359 If PRETEND_OUTGOING_VARARGS_NAMED is set and STRICT_ARGUMENT_NAMING is
2360 zero, this machine will be able to place unnamed args that were
2361 passed in registers into the stack. So treat all args as named.
2362 This allows the insns emitting for a specific argument list to be
2363 independent of the function declaration.
2365 If PRETEND_OUTGOING_VARARGS_NAMED is not set, we do not have any
2366 reliable way to pass unnamed args in registers, so we must force
2367 them into memory. */
2372 n_named_args
2374 /* Don't include the last named arg. */
2376 /* Count the struct value address, if it is passed as a parm. */
2378 else
2379 /* If we know nothing, treat all args as named. */
2382 /* Start updating where the next arg would go.
2384 On some machines (such as the PA) indirect calls have a different
2385 calling convention than normal calls. The last argument in
2386 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2387 or not. */
2390 /* Make a vector to hold all the information about each arg. */
2394 /* Build up entries in the ARGS array, compute the size of the
2395 arguments into ARGS_SIZE, etc. */
2403 {
2404 /* If this function requires a variable-sized argument list, don't
2405 try to make a cse'able block for this call. We may be able to
2406 do this eventually, but it is too complicated to keep track of
2407 what insns go in the cse'able block and which don't. */
2411 }
2413 /* Now make final decision about preallocating stack space. */
2418 /* If the structure value address will reference the stack pointer, we
2419 must stabilize it. We don't need to do this if we know that we are
2420 not going to adjust the stack pointer in processing this call. */
2425 structure_value_addr))
2430 /* Tail calls can make things harder to debug, and we're traditionally
2431 pushed these optimizations into -O2. Don't try if we're already
2432 expanding a call, as that means we're an argument. Don't try if
2433 there's cleanups, as we know there's code to follow the call.
2435 If rtx_equal_function_value_matters is false, that means we've
2436 finished with regular parsing. Which means that some of the
2437 machinery we use to generate tail-calls is no longer in place.
2438 This is most often true of sjlj-exceptions, which we couldn't
2439 tail-call to anyway. */
2442 || !flag_optimize_sibling_calls
2443 || !rtx_equal_function_value_matters
2448 /* Tail recursion fails, when we are not dealing with recursive calls. */
2454 /* Rest of purposes for tail call optimizations to fail. */
2456 #ifdef HAVE_sibcall_epilogue
2457 !HAVE_sibcall_epilogue
2458 #else
2459 1
2460 #endif
2461 || !try_tail_call
2462 /* Doing sibling call optimization needs some work, since
2463 structure_value_addr can be allocated on the stack.
2464 It does not seem worth the effort since few optimizable
2465 sibling calls will return a structure. */
2467 /* Check whether the target is able to optimize the call
2468 into a sibcall. */
2470 /* Functions that do not return exactly once may not be sibcall
2471 optimized. */
2474 /* If this function requires more stack slots than the current
2475 function, we cannot change it into a sibling call. */
2477 /* If the callee pops its own arguments, then it must pop exactly
2478 the same number of arguments as the current function. */
2482 current_function_args_size))
2486 {
2489 /* Ok, we're going to give the tail call the old college try.
2490 This means we're going to evaluate the function arguments
2491 up to three times. There are two degrees of badness we can
2492 encounter, those that can be unsaved and those that can't.
2493 (See unsafe_for_reeval commentary for details.)
2495 Generate a new argument list. Pass safe arguments through
2496 unchanged. For the easy badness wrap them in UNSAVE_EXPRs.
2497 For hard badness, evaluate them now and put their resulting
2498 rtx in a temporary VAR_DECL.
2500 initialize_argument_information has ordered the array for the
2501 order to be pushed, and we must remember this when reconstructing
2502 the original argument order. */
2505 {
2509 }
2510 else
2511 {
2515 }
2518 {
2520 {
2529 {
2536 }
2541 }
2542 /* We need to build actparms for optimize_tail_recursion. We can
2543 safely trash away TREE_PURPOSE, since it is unused by this
2544 function. */
2547 }
2548 /* Expanding one of those dangerous arguments could have added
2549 cleanups, but otherwise give it a whirl. */
2552 }
2554 /* Generate a tail recursion sequence when calling ourselves. */
2557 {
2558 /* We want to emit any pending stack adjustments before the tail
2559 recursion "call". That way we know any adjustment after the tail
2560 recursion call can be ignored if we indeed use the tail recursion
2561 call expansion. */
2565 /* Emit any queued insns now; otherwise they would end up in
2566 only one of the alternates. */
2569 /* Use a new sequence to hold any RTL we generate. We do not even
2570 know if we will use this RTL yet. The final decision can not be
2571 made until after RTL generation for the entire function is
2572 complete. */
2574 /* If expanding any of the arguments creates cleanups, we can't
2575 do a tailcall. So, we'll need to pop the pending cleanups
2576 list. If, however, all goes well, and there are no cleanups
2577 then the call to expand_start_target_temps will have no
2578 effect. */
2581 {
2584 else
2586 }
2590 /* Restore the original pending stack adjustment for the sibling and
2591 normal call cases below. */
2594 }
2597 {
2598 /* A fork duplicates the profile information, and an exec discards
2599 it. We can't rely on fork/exec to be paired. So write out the
2600 profile information we have gathered so far, and clear it. */
2601 /* ??? When Linux's __clone is called with CLONE_VM set, profiling
2602 is subject to race conditions, just as with multithreaded
2603 programs. */
2606 LCT_ALWAYS_RETURN,
2608 }
2610 /* Ensure current function's preferred stack boundary is at least
2611 what we need. We don't have to increase alignment for recursive
2612 functions. */
2619 function_call_count++;
2621 /* We want to make two insn chains; one for a sibling call, the other
2622 for a normal call. We will select one of the two chains after
2623 initial RTL generation is complete. */
2625 {
2627 /* We want to emit any pending stack adjustments before the tail
2628 recursion "call". That way we know any adjustment after the tail
2629 recursion call can be ignored if we indeed use the tail recursion
2630 call expansion. */
2633 rtx insns;
2637 {
2641 /* Emit any queued insns now; otherwise they would end up in
2642 only one of the alternates. */
2645 /* State variables we need to save and restore between
2646 iterations. */
2649 }
2652 else
2655 /* Other state variables that we must reinitialize each time
2656 through the loop (that are not initialized by the loop itself). */
2660 /* Start a new sequence for the normal call case.
2662 From this point on, if the sibling call fails, we want to set
2663 sibcall_failure instead of continuing the loop. */
2667 {
2668 /* We know at this point that there are not currently any
2669 pending cleanups. If, however, in the process of evaluating
2670 the arguments we were to create some, we'll need to be
2671 able to get rid of them. */
2673 }
2675 /* Don't let pending stack adjusts add up to too much.
2676 Also, do all pending adjustments now if there is any chance
2677 this might be a call to alloca or if we are expanding a sibling
2678 call sequence or if we are calling a function that is to return
2679 with stack pointer depressed. */
2686 /* When calling a const function, we must pop the stack args right away,
2687 so that the pop is deleted or moved with the call. */
2689 NO_DEFER_POP;
2691 #ifdef FINAL_REG_PARM_STACK_SPACE
2694 #endif
2695 /* Precompute any arguments as needed. */
2699 /* Now we are about to start emitting insns that can be deleted
2700 if a libcall is deleted. */
2705 /* Compute the actual size of the argument block required. The variable
2706 and constant sizes must be combined, the size may have to be rounded,
2707 and there may be a minimum required size. When generating a sibcall
2708 pattern, do not round up, since we'll be re-using whatever space our
2709 caller provided. */
2710 unadjusted_args_size
2718 /* The argument block when performing a sibling call is the
2719 incoming argument block. */
2721 {
2723 argblock
2724 #ifdef STACK_GROWS_DOWNWARD
2726 #else
2728 #endif
2731 }
2733 /* If we have no actual push instructions, or shouldn't use them,
2734 make space for all args right now. */
2736 {
2738 {
2742 /* stack_arg_under_construction says whether a stack arg is
2743 being constructed at the old stack level. Pushing the stack
2744 gets a clean outgoing argument block. */
2747 }
2749 }
2750 else
2751 {
2752 /* Note that we must go through the motions of allocating an argument
2753 block even if the size is zero because we may be storing args
2754 in the area reserved for register arguments, which may be part of
2755 the stack frame. */
2759 /* Store the maximum argument space used. It will be pushed by
2760 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2761 checking). */
2767 {
2769 {
2770 /* Since the stack pointer will never be pushed, it is
2771 possible for the evaluation of a parm to clobber
2772 something we have already written to the stack.
2773 Since most function calls on RISC machines do not use
2774 the stack, this is uncommon, but must work correctly.
2776 Therefore, we save any area of the stack that was already
2777 written and that we are using. Here we set up to do this
2778 by making a new stack usage map from the old one. The
2779 actual save will be done by store_one_arg.
2781 Another approach might be to try to reorder the argument
2782 evaluations to avoid this conflicting stack usage. */
2784 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2785 /* Since we will be writing into the entire argument area,
2786 the map must be allocated for its entire size, not just
2787 the part that is the responsibility of the caller. */
2789 #endif
2791 #ifdef ARGS_GROW_DOWNWARD
2794 #else
2796 needed);
2797 #endif
2798 stack_usage_map
2803 initial_highest_arg_in_use);
2807 (highest_outgoing_arg_in_use
2811 /* The address of the outgoing argument list must not be
2812 copied to a register here, because argblock would be left
2813 pointing to the wrong place after the call to
2814 allocate_dynamic_stack_space below. */
2817 }
2818 else
2819 {
2821 {
2822 /* Try to reuse some or all of the pending_stack_adjust
2823 to get this space. */
2824 needed
2825 = (combine_pending_stack_adjustment_and_call
2828 preferred_unit_stack_boundary));
2830 /* combine_pending_stack_adjustment_and_call computes
2831 an adjustment before the arguments are allocated.
2832 Account for them and see whether or not the stack
2833 needs to go up or down. */
2837 {
2838 /* We're releasing stack space. */
2839 /* ??? We can avoid any adjustment at all if we're
2840 already aligned. FIXME. */
2844 }
2845 else
2846 /* We need to allocate space. We'll do that in
2847 push_block below. */
2849 }
2851 /* Special case this because overhead of `push_block' in
2852 this case is non-trivial. */
2855 else
2858 /* We only really need to call `copy_to_reg' in the case
2859 where push insns are going to be used to pass ARGBLOCK
2860 to a function call in ARGS. In that case, the stack
2861 pointer changes value from the allocation point to the
2862 call point, and hence the value of
2863 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2864 as well always do it. */
2867 /* The save/restore code in store_one_arg handles all
2868 cases except one: a constructor call (including a C
2869 function returning a BLKmode struct) to initialize
2870 an argument. */
2872 {
2873 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2876 #else
2878 #endif
2880 {
2882 NULL_RTX);
2885 /* stack_arg_under_construction says whether a stack
2886 arg is being constructed at the old stack level.
2887 Pushing the stack gets a clean outgoing argument
2888 block. */
2889 old_stack_arg_under_construction
2892 /* Make a new map for the new argument list. */
2897 }
2899 BITS_PER_UNIT);
2900 }
2901 /* If argument evaluation might modify the stack pointer,
2902 copy the address of the argument list to a register. */
2905 {
2908 }
2909 }
2910 }
2911 }
2915 /* If we push args individually in reverse order, perform stack alignment
2916 before the first push (the last arg). */
2919 {
2920 /* When the stack adjustment is pending, we get better code
2921 by combining the adjustments. */
2925 {
2926 pending_stack_adjust
2927 = (combine_pending_stack_adjustment_and_call
2930 preferred_unit_stack_boundary));
2932 }
2936 }
2937 /* Now that the stack is properly aligned, pops can't safely
2938 be deferred during the evaluation of the arguments. */
2939 NO_DEFER_POP;
2943 /* Figure out the register where the value, if any, will come back. */
2947 {
2951 else
2953 }
2955 /* Precompute all register parameters. It isn't safe to compute anything
2956 once we have started filling any specific hard regs. */
2959 #ifdef REG_PARM_STACK_SPACE
2960 /* Save the fixed argument area if it's part of the caller's frame and
2961 is clobbered by argument setup for this call. */
2965 #endif
2967 /* Now store (and compute if necessary) all non-register parms.
2968 These come before register parms, since they can require block-moves,
2969 which could clobber the registers used for register parms.
2970 Parms which have partial registers are not stored here,
2971 but we do preallocate space here if they want that. */
2975 {
2980 reg_parm_stack_space)
2985 }
2987 /* If we have a parm that is passed in registers but not in memory
2988 and whose alignment does not permit a direct copy into registers,
2989 make a group of pseudos that correspond to each register that we
2990 will later fill. */
2994 /* Now store any partially-in-registers parm.
2995 This is the last place a block-move can happen. */
2999 {
3004 reg_parm_stack_space)
3009 }
3011 /* If we pushed args in forward order, perform stack alignment
3012 after pushing the last arg. */
3017 /* If register arguments require space on the stack and stack space
3018 was not preallocated, allocate stack space here for arguments
3019 passed in registers. */
3020 #ifdef OUTGOING_REG_PARM_STACK_SPACE
3024 #endif
3026 /* Pass the function the address in which to return a
3027 structure value. */
3029 {
3033 NULL_RTX)));
3037 }
3045 /* Perform postincrements before actually calling the function. */
3048 /* Save a pointer to the last insn before the call, so that we can
3049 later safely search backwards to find the CALL_INSN. */
3052 /* Set up next argument register. For sibling calls on machines
3053 with register windows this should be the incoming register. */
3054 #ifdef FUNCTION_INCOMING_ARG
3058 else
3059 #endif
3063 /* All arguments and registers used for the call must be set up by
3064 now! */
3066 /* Stack must be properly aligned now. */
3070 /* Generate the actual call instruction. */
3076 /* Verify that we've deallocated all the stack we used. */
3081 /* If call is cse'able, make appropriate pair of reg-notes around it.
3082 Test valreg so we don't crash; may safely ignore `const'
3083 if return type is void. Disable for PARALLEL return values, because
3084 we have no way to move such values into a pseudo register. */
3086 {
3087 rtx insns;
3090 {
3094 }
3095 else
3096 {
3100 /* Mark the return value as a pointer if needed. */
3105 /* Construct an "equal form" for the value which mentions all the
3106 arguments in order as well as the function name. */
3120 note);
3125 }
3126 }
3128 {
3132 /* The return value from a malloc-like function is a pointer. */
3138 /* The return value from a malloc-like function can not alias
3139 anything else. */
3144 /* Write out the sequence. */
3149 }
3151 /* For calls to `setjmp', etc., inform flow.c it should complain
3152 if nonvolatile values are live. For functions that cannot return,
3153 inform flow that control does not fall through. */
3156 {
3157 /* The barrier must be emitted
3158 immediately after the CALL_INSN. Some ports emit more
3159 than just a CALL_INSN above, so we must search for it here. */
3163 {
3165 /* There was no CALL_INSN? */
3168 }
3171 }
3176 /* If this function is returning into a memory location marked as
3177 readonly, it means it is initializing that location. But we normally
3178 treat functions as not clobbering such locations, so we need to
3179 specify that this one does. */
3184 /* If value type not void, return an rtx for the value. */
3186 /* If there are cleanups to be called, don't use a hard reg as target.
3187 We need to double check this and see if it matters anymore. */
3189 {
3194 }
3200 {
3202 {
3203 target
3206 structure_value_addr));
3208 }
3209 }
3211 {
3212 /* This is the special C++ case where we need to
3213 know what the true target was. We take care to
3214 never use this value more than once in one expression. */
3218 }
3219 /* Handle calls that return values in multiple non-contiguous locations.
3220 The Irix 6 ABI has examples of this. */
3222 {
3224 {
3225 /* This will only be assigned once, so it can be readonly. */
3232 }
3238 /* We can not support sibling calls for this case. */
3240 }
3244 {
3245 /* TARGET and VALREG cannot be equal at this point because the
3246 latter would not have REG_FUNCTION_VALUE_P true, while the
3247 former would if it were referring to the same register.
3249 If they refer to the same register, this move will be a no-op,
3250 except when function inlining is being done. */
3252 }
3254 {
3257 /* We can not support sibling calls for this case. */
3259 }
3260 else
3263 #ifdef PROMOTE_FUNCTION_RETURN
3264 /* If we promoted this return value, make the proper SUBREG. TARGET
3265 might be const0_rtx here, so be careful. */
3269 {
3274 /* If we don't promote as expected, something is wrong. */
3282 {
3289 }
3293 }
3294 #endif
3296 /* If size of args is variable or this was a constructor call for a stack
3297 argument, restore saved stack-pointer value. */
3300 {
3307 }
3309 {
3310 #ifdef REG_PARM_STACK_SPACE
3312 {
3315 }
3316 #endif
3318 /* If we saved any argument areas, restore them. */
3321 {
3323 rtx stack_area
3330 else
3333 BLOCK_OP_CALL_PARM);
3334 }
3338 }
3340 /* If this was alloca, record the new stack level for nonlocal gotos.
3341 Check for the handler slots since we might not have a save area
3342 for non-local gotos. */
3347 /* Free up storage we no longer need. */
3353 {
3354 /* Undo the fake expand_start_target_temps we did earlier. If
3355 there had been any cleanups created, we've already set
3356 sibcall_failure. */
3358 }
3364 {
3367 /* Restore the pending stack adjustment now that we have
3368 finished generating the sibling call sequence. */
3373 /* Prepare arg structure for next iteration. */
3375 {
3379 }
3382 }
3383 else
3386 /* If something prevents making this a sibling call,
3387 zero out the sequence. */
3390 }
3392 /* The function optimize_sibling_and_tail_recursive_calls doesn't
3393 handle CALL_PLACEHOLDERs inside other CALL_PLACEHOLDERs. This
3394 can happen if the arguments to this function call an inline
3395 function who's expansion contains another CALL_PLACEHOLDER.
3397 If there are any C_Ps in any of these sequences, replace them
3398 with their normal call. */
3415 /* If this was a potential tail recursion site, then emit a
3416 CALL_PLACEHOLDER with the normal and the tail recursion streams.
3417 One of them will be selected later. */
3419 {
3420 /* The tail recursion label must be kept around. We could expose
3421 its use in the CALL_PLACEHOLDER, but that creates unwanted edges
3422 and makes determining true tail recursion sites difficult.
3424 So we set LABEL_PRESERVE_P here, then clear it when we select
3425 one of the call sequences after rtl generation is complete. */
3429 tail_call_insns,
3430 tail_recursion_insns,
3431 tail_recursion_label));
3432 }
3433 else
3436 currently_expanding_call--;
3438 /* If this function returns with the stack pointer depressed, ensure
3439 this block saves and restores the stack pointer, show it was
3440 changed, and adjust for any outgoing arg space. */
3442 {
3447 }
3450 }
3451 \f
3452 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3453 The RETVAL parameter specifies whether return value needs to be saved, other
3454 parameters are documented in the emit_library_call function below. */
3456 static rtx
3459 rtx orgfun;
3460 rtx value;
3465 {
3466 /* Total size in bytes of all the stack-parms scanned so far. */
3468 /* Size of arguments before any adjustments (such as rounding). */
3471 rtx fun;
3476 CUMULATIVE_ARGS args_so_far;
3477 struct arg
3478 {
3479 rtx value;
3481 rtx reg;
3485 rtx save_area;
3486 };
3491 rtx valreg;
3497 rtx before_call;
3500 #ifdef REG_PARM_STACK_SPACE
3501 /* Define the boundary of the register parm stack space that needs to be
3502 save, if any. */
3505 #endif
3507 /* Size of the stack reserved for parameter registers. */
3511 #ifdef REG_PARM_STACK_SPACE
3512 #ifdef MAYBE_REG_PARM_STACK_SPACE
3514 #else
3516 #endif
3517 #endif
3519 /* By default, library functions can not throw. */
3523 {
3550 }
3553 /* Ensure current function's preferred stack boundary is at least
3554 what we need. */
3558 /* If this kind of value comes back in memory,
3559 decide where in memory it should come back. */
3561 {
3564 {
3565 #ifdef PCC_STATIC_STRUCT_RETURN
3566 rtx pointer_reg
3576 else
3578 #endif
3579 /* This call returns a big structure. */
3581 }
3582 }
3583 else
3586 /* ??? Unfinished: must pass the memory address as an argument. */
3588 /* Copy all the libcall-arguments out of the varargs data
3589 and into a vector ARGVEC.
3591 Compute how to pass each argument. We only support a very small subset
3592 of the full argument passing conventions to limit complexity here since
3593 library functions shouldn't have many args. */
3598 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3600 #else
3602 #endif
3609 /* Now we are about to start emitting insns that can be deleted
3610 if a libcall is deleted. */
3616 /* If there's a structure value address to be passed,
3617 either pass it in the special place, or pass it as an extra argument. */
3619 {
3621 nargs++;
3623 /* Make sure it is a reasonable operand for a move or push insn. */
3633 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3636 #endif
3639 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3641 #else
3643 #endif
3653 count++;
3654 }
3657 {
3661 /* We cannot convert the arg value to the mode the library wants here;
3662 must do it earlier where we know the signedness of the arg. */
3667 /* On some machines, there's no way to pass a float to a library fcn.
3668 Pass it as a double instead. */
3669 #ifdef LIBGCC_NEEDS_DOUBLE
3672 #endif
3674 /* There's no need to call protect_from_queue, because
3675 either emit_move_insn or emit_push_insn will do that. */
3677 /* Make sure it is a reasonable operand for a move or push insn. */
3682 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
3684 {
3685 rtx slot;
3687 #ifdef FUNCTION_ARG_CALLEE_COPIES
3690 #endif
3691 ;
3693 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3694 functions, so we have to pretend this isn't such a function. */
3696 {
3700 }
3703 /* If this was a CONST function, it is now PURE since
3704 it now reads memory. */
3706 {
3709 }
3714 {
3718 }
3719 else
3720 {
3725 build_pointer_type
3729 }
3733 call_fusage);
3737 slot),
3738 call_fusage);
3742 }
3743 #endif
3750 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3753 #else
3755 #endif
3758 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3760 #else
3762 #endif
3777 }
3779 #ifdef FINAL_REG_PARM_STACK_SPACE
3782 #endif
3783 /* If this machine requires an external definition for library
3784 functions, write one out. */
3789 + stack_pointer_delta
3791 / STACK_BYTES
3796 reg_parm_stack_space);
3798 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3800 #endif
3806 {
3807 /* Since the stack pointer will never be pushed, it is possible for
3808 the evaluation of a parm to clobber something we have already
3809 written to the stack. Since most function calls on RISC machines
3810 do not use the stack, this is uncommon, but must work correctly.
3812 Therefore, we save any area of the stack that was already written
3813 and that we are using. Here we set up to do this by making a new
3814 stack usage map from the old one.
3816 Another approach might be to try to reorder the argument
3817 evaluations to avoid this conflicting stack usage. */
3821 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3822 /* Since we will be writing into the entire argument area, the
3823 map must be allocated for its entire size, not just the part that
3824 is the responsibility of the caller. */
3826 #endif
3828 #ifdef ARGS_GROW_DOWNWARD
3831 #else
3833 needed);
3834 #endif
3839 initial_highest_arg_in_use);
3846 /* We must be careful to use virtual regs before they're instantiated,
3847 and real regs afterwards. Loop optimization, for example, can create
3848 new libcalls after we've instantiated the virtual regs, and if we
3849 use virtuals anyway, they won't match the rtl patterns. */
3853 else
3855 }
3856 else
3857 {
3860 }
3862 /* If we push args individually in reverse order, perform stack alignment
3863 before the first push (the last arg). */
3869 {
3872 }
3873 else
3874 {
3877 }
3879 #ifdef REG_PARM_STACK_SPACE
3881 {
3882 /* The argument list is the property of the called routine and it
3883 may clobber it. If the fixed area has been used for previous
3884 parameters, we must save and restore it.
3886 Here we compute the boundary of the that needs to be saved, if any. */
3888 #ifdef ARGS_GROW_DOWNWARD
3890 #else
3892 #endif
3893 {
3902 }
3905 {
3907 enum machine_mode save_mode
3909 rtx stack_area;
3911 /* If we don't have the required alignment, must do this in BLKmode. */
3916 #ifdef ARGS_GROW_DOWNWARD
3921 #else
3925 low_to_save)));
3926 #endif
3928 {
3932 BLOCK_OP_CALL_PARM);
3933 }
3934 else
3935 {
3938 }
3939 }
3940 }
3941 #endif
3943 /* Push the args that need to be pushed. */
3945 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
3946 are to be pushed. */
3948 {
3956 {
3958 {
3959 /* If this is being stored into a pre-allocated, fixed-size,
3960 stack area, save any previous data at that location. */
3962 #ifdef ARGS_GROW_DOWNWARD
3963 /* stack_slot is negative, but we want to index stack_usage_map
3964 with positive values. */
3967 #else
3970 #endif
3974 /* Don't store things in the fixed argument area at this
3975 point; it has already been saved. */
3980 {
3981 /* We need to make a save area. See what mode we can make
3982 it. */
3983 enum machine_mode save_mode
3987 rtx stack_area
3988 = gen_rtx_MEM
3990 memory_address
3997 }
3998 }
4005 /* Now mark the segment we just used. */
4010 NO_DEFER_POP;
4011 }
4012 }
4014 /* If we pushed args in forward order, perform stack alignment
4015 after pushing the last arg. */
4022 else
4027 /* Now load any reg parms into their regs. */
4029 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4030 are to be pushed. */
4032 {
4037 /* Handle calls that pass values in multiple non-contiguous
4038 locations. The PA64 has examples of this for library calls. */
4044 NO_DEFER_POP;
4045 }
4047 /* Any regs containing parms remain in use through the call. */
4049 {
4055 }
4057 /* Pass the function the address in which to return a structure value. */
4059 {
4063 NULL_RTX)));
4066 }
4068 /* Don't allow popping to be deferred, since then
4069 cse'ing of library calls could delete a call and leave the pop. */
4070 NO_DEFER_POP;
4074 /* Stack must be properly aligned now. */
4080 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4081 will set inhibit_defer_pop to that value. */
4082 /* The return type is needed to decide how many bytes the function pops.
4083 Signedness plays no role in that, so for simplicity, we pretend it's
4084 always signed. We also assume that the list of arguments passed has
4085 no impact, so we pretend it is unknown. */
4091 struct_value_size,
4093 valreg,
4096 /* For calls to `setjmp', etc., inform flow.c it should complain
4097 if nonvolatile values are live. For functions that cannot return,
4098 inform flow that control does not fall through. */
4101 {
4102 /* The barrier note must be emitted
4103 immediately after the CALL_INSN. Some ports emit more than
4104 just a CALL_INSN above, so we must search for it here. */
4108 {
4110 /* There was no CALL_INSN? */
4113 }
4116 }
4118 /* Now restore inhibit_defer_pop to its actual original value. */
4119 OK_DEFER_POP;
4121 /* If call is cse'able, make appropriate pair of reg-notes around it.
4122 Test valreg so we don't crash; may safely ignore `const'
4123 if return type is void. Disable for PARALLEL return values, because
4124 we have no way to move such values into a pseudo register. */
4126 {
4127 rtx insns;
4130 {
4134 }
4135 else
4136 {
4141 /* Construct an "equal form" for the value which mentions all the
4142 arguments in order as well as the function name. */
4155 note);
4160 }
4161 }
4164 /* Copy the value to the right place. */
4166 {
4168 {
4173 }
4176 else
4178 }
4181 {
4182 #ifdef REG_PARM_STACK_SPACE
4184 {
4186 #ifdef ARGS_GROW_DOWNWARD
4187 rtx stack_area
4192 #else
4193 rtx stack_area
4197 #endif
4202 else
4205 BLOCK_OP_CALL_PARM);
4206 }
4207 #endif
4209 /* If we saved any argument areas, restore them. */
4212 {
4214 rtx stack_area
4216 memory_address
4222 }
4226 }
4230 }
4231 \f
4232 /* Output a library call to function FUN (a SYMBOL_REF rtx)
4233 (emitting the queue unless NO_QUEUE is nonzero),
4234 for a value of mode OUTMODE,
4235 with NARGS different arguments, passed as alternating rtx values
4236 and machine_modes to convert them to.
4237 The rtx values should have been passed through protect_from_queue already.
4239 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
4240 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
4241 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
4242 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
4243 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
4244 or other LCT_ value for other types of library calls. */
4246 void
4249 {
4259 }
4260 \f
4261 /* Like emit_library_call except that an extra argument, VALUE,
4262 comes second and says where to store the result.
4263 (If VALUE is zero, this function chooses a convenient way
4264 to return the value.
4266 This function returns an rtx for where the value is to be found.
4267 If VALUE is nonzero, VALUE is returned. */
4269 rtx
4273 {
4274 rtx result;
4289 }
4290 \f
4291 /* Store a single argument for a function call
4292 into the register or memory area where it must be passed.
4293 *ARG describes the argument value and where to pass it.
4295 ARGBLOCK is the address of the stack-block for all the arguments,
4296 or 0 on a machine where arguments are pushed individually.
4298 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4299 so must be careful about how the stack is used.
4301 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4302 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4303 that we need not worry about saving and restoring the stack.
4305 FNDECL is the declaration of the function we are calling.
4307 Return nonzero if this arg should cause sibcall failure,
4308 zero otherwise. */
4310 static int
4313 rtx argblock;
4317 {
4328 /* Push a new temporary level for any temporaries we make for
4329 this argument. */
4333 {
4334 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4335 save any previous data at that location. */
4337 {
4338 #ifdef ARGS_GROW_DOWNWARD
4339 /* stack_slot is negative, but we want to index stack_usage_map
4340 with positive values. */
4343 else
4347 #else
4350 else
4354 #endif
4358 /* Don't store things in the fixed argument area at this point;
4359 it has already been saved. */
4364 {
4365 /* We need to make a save area. See what mode we can make it. */
4366 enum machine_mode save_mode
4368 rtx stack_area
4374 {
4383 BLOCK_OP_CALL_PARM);
4384 }
4385 else
4386 {
4389 }
4390 }
4391 }
4392 /* Now that we have saved any slots that will be overwritten by this
4393 store, mark all slots this store will use. We must do this before
4394 we actually expand the argument since the expansion itself may
4395 trigger library calls which might need to use the same stack slot. */
4399 }
4401 /* If this isn't going to be placed on both the stack and in registers,
4402 set up the register and number of words. */
4404 {
4407 else
4410 }
4413 /* Being passed entirely in a register. We shouldn't be called in
4414 this case. */
4417 /* If this arg needs special alignment, don't load the registers
4418 here. */
4422 /* If this is being passed partially in a register, we can't evaluate
4423 it directly into its stack slot. Otherwise, we can. */
4425 {
4426 /* stack_arg_under_construction is nonzero if a function argument is
4427 being evaluated directly into the outgoing argument list and
4428 expand_call must take special action to preserve the argument list
4429 if it is called recursively.
4431 For scalar function arguments stack_usage_map is sufficient to
4432 determine which stack slots must be saved and restored. Scalar
4433 arguments in general have pass_on_stack == 0.
4435 If this argument is initialized by a function which takes the
4436 address of the argument (a C++ constructor or a C function
4437 returning a BLKmode structure), then stack_usage_map is
4438 insufficient and expand_call must push the stack around the
4439 function call. Such arguments have pass_on_stack == 1.
4441 Note that it is always safe to set stack_arg_under_construction,
4442 but this generates suboptimal code if set when not needed. */
4445 stack_arg_under_construction++;
4448 (partial
4453 /* If we are promoting object (or for any other reason) the mode
4454 doesn't agree, convert the mode. */
4461 stack_arg_under_construction--;
4462 }
4464 /* Don't allow anything left on stack from computation
4465 of argument to alloca. */
4470 /* If the value is already in the stack slot, we are done. */
4471 ;
4473 {
4476 /* Argument is a scalar, not entirely passed in registers.
4477 (If part is passed in registers, arg->partial says how much
4478 and emit_push_insn will take care of putting it there.)
4480 Push it, and if its size is less than the
4481 amount of space allocated to it,
4482 also bump stack pointer by the additional space.
4483 Note that in C the default argument promotions
4484 will prevent such mismatches. */
4487 /* Compute how much space the push instruction will push.
4488 On many machines, pushing a byte will advance the stack
4489 pointer by a halfword. */
4490 #ifdef PUSH_ROUNDING
4492 #endif
4495 /* Compute how much space the argument should get:
4496 round up to a multiple of the alignment for arguments. */
4502 /* This isn't already where we want it on the stack, so put it there.
4503 This can either be done with push or copy insns. */
4509 /* Unless this is a partially-in-register argument, the argument is now
4510 in the stack. */
4513 }
4514 else
4515 {
4516 /* BLKmode, at least partly to be pushed. */
4520 rtx size_rtx;
4522 /* Pushing a nonscalar.
4523 If part is passed in registers, PARTIAL says how much
4524 and emit_push_insn will take care of putting it there. */
4526 /* Round its size up to a multiple
4527 of the allocation unit for arguments. */
4530 {
4533 }
4534 else
4535 {
4536 /* PUSH_ROUNDING has no effect on us, because
4537 emit_push_insn for BLKmode is careful to avoid it. */
4542 }
4544 /* Some types will require stricter alignment, which will be
4545 provided for elsewhere in argument layout. */
4548 /* When an argument is padded down, the block is aligned to
4549 PARM_BOUNDARY, but the actual argument isn't. */
4551 {
4555 {
4558 }
4559 }
4562 {
4563 /* emit_push_insn might not work properly if arg->value and
4564 argblock + arg->offset areas overlap. */
4571 current_function_internal_arg_pointer
4573 {
4577 /* expand_call should ensure this */
4582 {
4585 }
4587 {
4590 }
4591 }
4592 }
4594 /* Special handling is required if part of the parameter lies in the
4595 register parameter area. The argument may be copied into the stack
4596 slot using memcpy(), but the original contents of the register
4597 parameter area will be restored after the memcpy() call.
4599 To ensure that the part that lies in the register parameter area
4600 is copied correctly, we emit a separate push for that part. This
4601 push should be small enough to avoid a call to memcpy(). */
4602 #ifndef STACK_PARMS_IN_REG_PARM_AREA
4604 #else
4606 #endif
4607 {
4615 {
4621 }
4622 }
4630 /* Unless this is a partially-in-register argument, the argument is now
4631 in the stack.
4633 ??? Unlike the case above, in which we want the actual
4634 address of the data, so that we can load it directly into a
4635 register, here we want the address of the stack slot, so that
4636 it's properly aligned for word-by-word copying or something
4637 like that. It's not clear that this is always correct. */
4640 }
4642 /* Once we have pushed something, pops can't safely
4643 be deferred during the rest of the arguments. */
4644 NO_DEFER_POP;
4646 /* ANSI doesn't require a sequence point here,
4647 but PCC has one, so this will avoid some problems. */
4650 /* Free any temporary slots made in processing this argument. Show
4651 that we might have taken the address of something and pushed that
4652 as an operand. */
4658 }