| blob | bd889e1ae71537f4b07377202598ac21c506f70c |
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, 2002, 2003 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. */
43 /* Decide whether a function's arguments should be processed
44 from first to last or from last to first.
46 They should if the stack and args grow in opposite directions, but
47 only if we have push insns. */
49 #ifdef PUSH_ROUNDING
51 #ifndef PUSH_ARGS_REVERSED
52 #if defined (STACK_GROWS_DOWNWARD) != defined (ARGS_GROW_DOWNWARD)
53 #define PUSH_ARGS_REVERSED PUSH_ARGS
54 #endif
55 #endif
57 #endif
59 #ifndef PUSH_ARGS_REVERSED
60 #define PUSH_ARGS_REVERSED 0
61 #endif
63 #ifndef STACK_POINTER_OFFSET
64 #define STACK_POINTER_OFFSET 0
65 #endif
67 /* Like PREFERRED_STACK_BOUNDARY but in units of bytes, not bits. */
68 #define STACK_BYTES (PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT)
70 /* Data structure and subroutines used within expand_call. */
72 struct arg_data
73 {
74 /* Tree node for this argument. */
75 tree tree_value;
76 /* Mode for value; TYPE_MODE unless promoted. */
78 /* Current RTL value for argument, or 0 if it isn't precomputed. */
79 rtx value;
80 /* Initially-compute RTL value for argument; only for const functions. */
81 rtx initial_value;
82 /* Register to pass this argument in, 0 if passed on stack, or an
83 PARALLEL if the arg is to be copied into multiple non-contiguous
84 registers. */
85 rtx reg;
86 /* Register to pass this argument in when generating tail call sequence.
87 This is not the same register as for normal calls on machines with
88 register windows. */
89 rtx tail_call_reg;
90 /* If REG was promoted from the actual mode of the argument expression,
91 indicates whether the promotion is sign- or zero-extended. */
93 /* Number of registers to use. 0 means put the whole arg in registers.
94 Also 0 if not passed in registers. */
96 /* Nonzero if argument must be passed on stack.
97 Note that some arguments may be passed on the stack
98 even though pass_on_stack is zero, just because FUNCTION_ARG says so.
99 pass_on_stack identifies arguments that *cannot* go in registers. */
101 /* Offset of this argument from beginning of stack-args. */
103 /* Similar, but offset to the start of the stack slot. Different from
104 OFFSET if this arg pads downward. */
106 /* Size of this argument on the stack, rounded up for any padding it gets,
107 parts of the argument passed in registers do not count.
108 If REG_PARM_STACK_SPACE is defined, then register parms
109 are counted here as well. */
111 /* Location on the stack at which parameter should be stored. The store
112 has already been done if STACK == VALUE. */
113 rtx stack;
114 /* Location on the stack of the start of this argument slot. This can
115 differ from STACK if this arg pads downward. This location is known
116 to be aligned to FUNCTION_ARG_BOUNDARY. */
117 rtx stack_slot;
118 /* Place that this stack area has been saved, if needed. */
119 rtx save_area;
120 /* If an argument's alignment does not permit direct copying into registers,
121 copy in smaller-sized pieces into pseudos. These are stored in a
122 block pointed to by this field. The next field says how many
123 word-sized pseudos we made. */
126 /* The amount that the stack pointer needs to be adjusted to
127 force alignment for the next argument. */
129 };
131 /* A vector of one char per byte of stack space. A byte if nonzero if
132 the corresponding stack location has been used.
133 This vector is used to prevent a function call within an argument from
134 clobbering any stack already set up. */
137 /* Size of STACK_USAGE_MAP. */
140 /* A bitmap of virtual-incoming stack space. Bit is set if the corresponding
141 stack location's tail call argument has been already stored into the stack.
142 This bitmap is used to prevent sibling call optimization if function tries
143 to use parent's incoming argument slots when they have been already
144 overwritten with tail call arguments. */
147 /* stack_arg_under_construction is nonzero when an argument may be
148 initialized with a constructor call (including a C function that
149 returns a BLKmode struct) and expand_call must take special action
150 to make sure the object being constructed does not overlap the
151 argument list for the constructor call. */
160 CUMULATIVE_ARGS *));
180 CUMULATIVE_ARGS *,
200 static int combine_pending_stack_adjustment_and_call
204 #ifdef REG_PARM_STACK_SPACE
207 #endif
208 \f
209 /* If WHICH is 1, return 1 if EXP contains a call to the built-in function
210 `alloca'.
212 If WHICH is 0, return 1 if EXP contains a call to any function.
213 Actually, we only need return 1 if evaluating EXP would require pushing
214 arguments on the stack, but that is too difficult to compute, so we just
215 assume any function call might require the stack. */
219 static int
221 tree exp;
223 {
230 }
232 /* Recursive function to do the work of above function. */
234 static int
236 tree exp;
238 {
244 /* If this code is language-specific, we don't know what it will do. */
249 {
255 && (TYPE_RETURNS_STACK_DEPRESSED
269 {
270 tree tem;
275 }
285 calls_function_save_exprs);
290 {
291 tree local;
292 tree subblock;
300 subblock;
304 }
315 }
317 /* Only expressions, references, and blocks can contain calls. */
327 }
328 \f
329 /* Force FUNEXP into a form suitable for the address of a CALL,
330 and return that as an rtx. Also load the static chain register
331 if FNDECL is a nested function.
333 CALL_FUSAGE points to a variable holding the prospective
334 CALL_INSN_FUNCTION_USAGE information. */
336 rtx
338 rtx funexp;
339 tree fndecl;
343 {
349 /* Get possible static chain value for nested function in C. */
352 /* Make a valid memory address and copy constants thru pseudo-regs,
353 but not for a constant address if -fno-function-cse. */
355 /* If we are using registers for parameters, force the
356 function address into a register now. */
361 {
362 #ifndef NO_FUNCTION_CSE
364 #ifdef NO_RECURSIVE_FUNCTION_CSE
366 #endif
368 #endif
369 }
372 {
377 }
380 }
382 /* Generate instructions to call function FUNEXP,
383 and optionally pop the results.
384 The CALL_INSN is the first insn generated.
386 FNDECL is the declaration node of the function. This is given to the
387 macro RETURN_POPS_ARGS to determine whether this function pops its own args.
389 FUNTYPE is the data type of the function. This is given to the macro
390 RETURN_POPS_ARGS to determine whether this function pops its own args.
391 We used to allow an identifier for library functions, but that doesn't
392 work when the return type is an aggregate type and the calling convention
393 says that the pointer to this aggregate is to be popped by the callee.
395 STACK_SIZE is the number of bytes of arguments on the stack,
396 ROUNDED_STACK_SIZE is that number rounded up to
397 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
398 both to put into the call insn and to generate explicit popping
399 code if necessary.
401 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
402 It is zero if this call doesn't want a structure value.
404 NEXT_ARG_REG is the rtx that results from executing
405 FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1)
406 just after all the args have had their registers assigned.
407 This could be whatever you like, but normally it is the first
408 arg-register beyond those used for args in this call,
409 or 0 if all the arg-registers are used in this call.
410 It is passed on to `gen_call' so you can put this info in the call insn.
412 VALREG is a hard register in which a value is returned,
413 or 0 if the call does not return a value.
415 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
416 the args to this call were processed.
417 We restore `inhibit_defer_pop' to that value.
419 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
420 denote registers used by the called function. */
422 static void
426 rtx funexp;
427 tree fndecl ATTRIBUTE_UNUSED;
428 tree funtype ATTRIBUTE_UNUSED;
429 HOST_WIDE_INT stack_size ATTRIBUTE_UNUSED;
430 HOST_WIDE_INT rounded_stack_size;
431 HOST_WIDE_INT struct_value_size ATTRIBUTE_UNUSED;
432 rtx next_arg_reg ATTRIBUTE_UNUSED;
433 rtx valreg;
435 rtx call_fusage;
438 {
440 rtx call_insn;
443 #if defined (HAVE_call) && defined (HAVE_call_value)
444 rtx struct_value_size_rtx;
446 #endif
448 #ifdef CALL_POPS_ARGS
450 #endif
452 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
453 and we don't want to load it into a register as an optimization,
454 because prepare_call_address already did it if it should be done. */
458 #if defined (HAVE_sibcall_pop) && defined (HAVE_sibcall_value_pop)
462 {
464 rtx pat;
466 /* If this subroutine pops its own args, record that in the call insn
467 if possible, for the sake of frame pointer elimination. */
473 n_pop);
474 else
480 }
481 else
482 #endif
484 #if defined (HAVE_call_pop) && defined (HAVE_call_value_pop)
485 /* If the target has "call" or "call_value" insns, then prefer them
486 if no arguments are actually popped. If the target does not have
487 "call" or "call_value" insns, then we must use the popping versions
488 even if the call has no arguments to pop. */
489 #if defined (HAVE_call) && defined (HAVE_call_value)
492 #else
494 #endif
495 {
497 rtx pat;
499 /* If this subroutine pops its own args, record that in the call insn
500 if possible, for the sake of frame pointer elimination. */
506 else
512 }
513 else
514 #endif
516 #if defined (HAVE_sibcall) && defined (HAVE_sibcall_value)
519 {
523 rounded_stack_size_rtx,
525 else
528 struct_value_size_rtx));
529 }
530 else
531 #endif
533 #if defined (HAVE_call) && defined (HAVE_call_value)
535 {
540 NULL_RTX));
541 else
544 struct_value_size_rtx));
545 }
546 else
547 #endif
550 /* Find the CALL insn we just emitted. */
554 ;
559 /* Mark memory as used for "pure" function call. */
561 call_fusage
562 = gen_rtx_EXPR_LIST
566 call_fusage);
568 /* Put the register usage information on the CALL. If there is already
569 some usage information, put ours at the end. */
571 {
572 rtx link;
576 ;
579 }
580 else
583 /* If this is a const call, then set the insn's unchanging bit. */
587 /* If this call can't throw, attach a REG_EH_REGION reg note to that
588 effect. */
592 else
603 {
607 }
611 /* Restore this now, so that we do defer pops for this call's args
612 if the context of the call as a whole permits. */
616 {
625 }
628 {
629 /* If returning from the subroutine does not automatically pop the args,
630 we need an instruction to pop them sooner or later.
631 Perhaps do it now; perhaps just record how much space to pop later.
633 If returning from the subroutine does pop the args, indicate that the
634 stack pointer will be changed. */
637 {
639 /* Just pretend we did the pop. */
644 else
646 }
647 }
648 /* When we accumulate outgoing args, we must avoid any stack manipulations.
649 Restore the stack pointer to its original value now. Usually
650 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
651 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
652 popping variants of functions exist as well.
654 ??? We may optimize similar to defer_pop above, but it is
655 probably not worthwhile.
657 ??? It will be worthwhile to enable combine_stack_adjustments even for
658 such machines. */
661 }
663 /* Determine if the function identified by NAME and FNDECL is one with
664 special properties we wish to know about.
666 For example, if the function might return more than one time (setjmp), then
667 set RETURNS_TWICE to a nonzero value.
669 Similarly set LONGJMP for if the function is in the longjmp family.
671 Set MAY_BE_ALLOCA for any memory allocation function that might allocate
672 space from the stack such as alloca. */
674 static int
676 tree fndecl;
678 {
682 /* Exclude functions not at the file scope, or not `extern',
683 since they are not the magic functions we would otherwise
684 think they are. */
686 {
690 /* We assume that alloca will always be called by name. It
691 makes no sense to pass it as a pointer-to-function to
692 anything that does not understand its behavior. */
701 /* Disregard prefix _, __ or __x. */
703 {
708 else
710 }
713 {
726 }
739 /* Linux specific: __clone. check NAME to insist on the
740 leading underscores, to avoid polluting the ISO / POSIX
741 namespace. */
750 }
752 }
754 /* Return nonzero when tree represent call to longjmp. */
756 int
758 tree fndecl;
759 {
761 }
763 /* Return true when exp contains alloca call. */
764 bool
766 tree exp;
767 {
776 }
778 /* Detect flags (function attributes) from the function decl or type node. */
780 int
782 tree exp;
783 {
788 {
793 {
798 }
800 /* The function exp may have the `malloc' attribute. */
804 /* The function exp may have the `pure' attribute. */
810 }
818 /* Mark if the function returns with the stack pointer depressed. We
819 cannot consider it pure or constant in that case. */
821 {
824 }
827 }
829 /* Precompute all register parameters as described by ARGS, storing values
830 into fields within the ARGS array.
832 NUM_ACTUALS indicates the total number elements in the ARGS array.
834 Set REG_PARM_SEEN if we encounter a register parameter. */
836 static void
841 {
848 {
852 {
859 /* ANSI doesn't require a sequence point here,
860 but PCC has one, so this will avoid some problems. */
862 }
864 /* If the value is a non-legitimate constant, force it into a
865 pseudo now. TLS symbols sometimes need a call to resolve. */
870 /* If we are to promote the function arg to a wider mode,
871 do it now. */
879 /* If the value is expensive, and we are inside an appropriately
880 short loop, put the value into a pseudo and then put the pseudo
881 into the hard reg.
883 For small register classes, also do this if this call uses
884 register parameters. This is to avoid reload conflicts while
885 loading the parameters registers. */
895 }
896 }
898 #ifdef REG_PARM_STACK_SPACE
900 /* The argument list is the property of the called routine and it
901 may clobber it. If the fixed area has been used for previous
902 parameters, we must save and restore it. */
904 static rtx
908 rtx argblock;
911 {
915 /* Compute the boundary of the area that needs to be saved, if any. */
917 #ifdef ARGS_GROW_DOWNWARD
919 #endif
925 {
929 rtx stack_area;
930 rtx save_area;
933 ;
941 /* If we don't have the required alignment, must do this
942 in BLKmode. */
947 #ifdef ARGS_GROW_DOWNWARD
949 #else
951 #endif
955 delta)));
959 {
963 }
964 else
965 {
968 }
971 }
974 }
976 static void
978 rtx save_area;
979 rtx argblock;
982 {
985 rtx stack_area;
987 #ifdef ARGS_GROW_DOWNWARD
989 #else
991 #endif
999 else
1002 BLOCK_OP_CALL_PARM);
1003 }
1006 /* If any elements in ARGS refer to parameters that are to be passed in
1007 registers, but not in memory, and whose alignment does not permit a
1008 direct copy into registers. Copy the values into a group of pseudos
1009 which we will later copy into the appropriate hard registers.
1011 Pseudos for each unaligned argument will be stored into the array
1012 args[argnum].aligned_regs. The caller is responsible for deallocating
1013 the aligned_regs array if it is nonzero. */
1015 static void
1019 {
1027 {
1038 /* Structures smaller than a word are aligned to the least
1039 significant byte (to the right). On a BYTES_BIG_ENDIAN machine,
1040 this means we must skip the empty high order bytes when
1041 calculating the bit offset. */
1047 {
1054 /* There is no need to restrict this code to loading items
1055 in TYPE_ALIGN sized hunks. The bitfield instructions can
1056 load up entire word sized registers efficiently.
1058 ??? This may not be needed anymore.
1059 We use to emit a clobber here but that doesn't let later
1060 passes optimize the instructions we emit. By storing 0 into
1061 the register later passes know the first AND to zero out the
1062 bitfield being set in the register is unnecessary. The store
1063 of 0 will be deleted as will at least the first AND. */
1071 BITS_PER_WORD),
1072 BITS_PER_WORD);
1073 }
1074 }
1075 }
1077 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
1078 ACTPARMS.
1080 NUM_ACTUALS is the total number of parameters.
1082 N_NAMED_ARGS is the total number of named arguments.
1084 FNDECL is the tree code for the target of this call (if known)
1086 ARGS_SO_FAR holds state needed by the target to know where to place
1087 the next argument.
1089 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
1090 for arguments which are passed in registers.
1092 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
1093 and may be modified by this routine.
1095 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
1096 flags which may may be modified by this routine. */
1098 static void
1103 ecf_flags)
1108 tree actparms;
1109 tree fndecl;
1116 {
1117 /* 1 if scanning parms front to back, -1 if scanning back to front. */
1120 /* Count arg position in order args appear. */
1125 tree p;
1130 /* In this loop, we consider args in the order they are written.
1131 We fill up ARGS from the front or from the back if necessary
1132 so that in any case the first arg to be pushed ends up at the front. */
1135 {
1137 /* In this case, must reverse order of args
1138 so that we compute and push the last arg first. */
1139 }
1140 else
1141 {
1143 }
1145 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1147 {
1154 /* Replace erroneous argument with constant zero. */
1158 /* If TYPE is a transparent union, pass things the way we would
1159 pass the first field of the union. We have already verified that
1160 the modes are the same. */
1164 /* Decide where to pass this arg.
1166 args[i].reg is nonzero if all or part is passed in registers.
1168 args[i].partial is nonzero if part but not all is passed in registers,
1169 and the exact value says how many words are passed in registers.
1171 args[i].pass_on_stack is nonzero if the argument must at least be
1172 computed on the stack. It may then be loaded back into registers
1173 if args[i].reg is nonzero.
1175 These decisions are driven by the FUNCTION_... macros and must agree
1176 with those made by function.c. */
1178 /* See if this argument should be passed by invisible reference. */
1182 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
1185 #endif
1186 )
1187 {
1188 /* If we're compiling a thunk, pass through invisible
1189 references instead of making a copy. */
1191 #ifdef FUNCTION_ARG_CALLEE_COPIES
1194 /* If it's in a register, we must make a copy of it too. */
1195 /* ??? Is this a sufficient test? Is there a better one? */
1199 #endif
1200 )
1201 {
1202 /* C++ uses a TARGET_EXPR to indicate that we want to make a
1203 new object from the argument. If we are passing by
1204 invisible reference, the callee will do that for us, so we
1205 can strip off the TARGET_EXPR. This is not always safe,
1206 but it is safe in the only case where this is a useful
1207 optimization; namely, when the argument is a plain object.
1208 In that case, the frontend is just asking the backend to
1209 make a bitwise copy of the argument. */
1220 }
1222 {
1223 /* In the V3 C++ ABI, parameters are destroyed in the caller.
1224 We implement this by passing the address of the temporary
1225 rather than expanding it into another allocated slot. */
1230 }
1231 else
1232 {
1233 /* We make a copy of the object and pass the address to the
1234 function being called. */
1235 rtx copy;
1241 STACK_CHECK_MAX_VAR_SIZE))))
1242 {
1243 /* This is a variable-sized object. Make space on the stack
1244 for it. */
1248 {
1252 }
1255 allocate_dynamic_stack_space
1258 }
1259 else
1269 }
1270 }
1275 #ifdef PROMOTE_FUNCTION_ARGS
1277 #endif
1284 #ifdef FUNCTION_INCOMING_ARG
1285 /* If this is a sibling call and the machine has register windows, the
1286 register window has to be unwinded before calling the routine, so
1287 arguments have to go into the incoming registers. */
1290 #else
1292 #endif
1294 #ifdef FUNCTION_ARG_PARTIAL_NREGS
1299 #endif
1303 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1304 it means that we are to pass this arg in the register(s) designated
1305 by the PARALLEL, but also to pass it in the stack. */
1310 /* If this is an addressable type, we must preallocate the stack
1311 since we must evaluate the object into its final location.
1313 If this is to be passed in both registers and the stack, it is simpler
1314 to preallocate. */
1319 /* If this is an addressable type, we cannot pre-evaluate it. Thus,
1320 we cannot consider this function call constant. */
1324 /* Compute the stack-size of this argument. */
1329 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1331 #else
1333 #endif
1337 #ifndef ARGS_GROW_DOWNWARD
1339 #endif
1343 /* If a part of the arg was put into registers,
1344 don't include that part in the amount pushed. */
1350 /* Update ARGS_SIZE, the total stack space for args so far. */
1354 {
1356 }
1358 /* Since the slot offset points to the bottom of the slot,
1359 we must record it after incrementing if the args grow down. */
1360 #ifdef ARGS_GROW_DOWNWARD
1366 #endif
1368 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1369 have been used, etc. */
1373 }
1374 }
1376 /* Update ARGS_SIZE to contain the total size for the argument block.
1377 Return the original constant component of the argument block's size.
1379 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1380 for arguments passed in registers. */
1382 static int
1384 preferred_stack_boundary)
1388 {
1391 /* For accumulate outgoing args mode we don't need to align, since the frame
1392 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1393 backends from generating misaligned frame sizes. */
1397 /* Compute the actual size of the argument block required. The variable
1398 and constant sizes must be combined, the size may have to be rounded,
1399 and there may be a minimum required size. */
1402 {
1408 {
1409 /* We don't handle this case yet. To handle it correctly we have
1410 to add the delta, round and subtract the delta.
1411 Currently no machine description requires this support. */
1415 }
1418 {
1419 args_size->var
1423 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1424 /* The area corresponding to register parameters is not to count in
1425 the size of the block we need. So make the adjustment. */
1426 args_size->var
1429 #endif
1430 }
1431 }
1432 else
1433 {
1438 + stack_pointer_delta
1440 / preferred_stack_boundary
1445 reg_parm_stack_space);
1447 #ifdef MAYBE_REG_PARM_STACK_SPACE
1450 #endif
1452 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1454 #endif
1455 }
1457 }
1459 /* Precompute parameters as needed for a function call.
1461 FLAGS is mask of ECF_* constants.
1463 NUM_ACTUALS is the number of arguments.
1465 ARGS is an array containing information for each argument; this
1466 routine fills in the INITIAL_VALUE and VALUE fields for each
1467 precomputed argument. */
1469 static void
1474 {
1477 /* If this function call is cse'able, precompute all the parameters.
1478 Note that if the parameter is constructed into a temporary, this will
1479 cause an additional copy because the parameter will be constructed
1480 into a temporary location and then copied into the outgoing arguments.
1481 If a parameter contains a call to alloca and this function uses the
1482 stack, precompute the parameter. */
1484 /* If we preallocated the stack space, and some arguments must be passed
1485 on the stack, then we must precompute any parameter which contains a
1486 function call which will store arguments on the stack.
1487 Otherwise, evaluating the parameter may clobber previous parameters
1488 which have already been stored into the stack. (we have code to avoid
1489 such case by saving the outgoing stack arguments, but it results in
1490 worse code) */
1495 {
1498 /* If this is an addressable type, we cannot pre-evaluate it. */
1505 /* ANSI doesn't require a sequence point here,
1506 but PCC has one, so this will avoid some problems. */
1514 {
1518 #ifdef PROMOTE_FOR_CALL_ONLY
1519 /* CSE will replace this only if it contains args[i].value
1520 pseudo, so convert it down to the declared mode using
1521 a SUBREG. */
1524 {
1530 }
1531 #endif
1532 }
1533 }
1534 }
1536 /* Given the current state of MUST_PREALLOCATE and information about
1537 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1538 compute and return the final value for MUST_PREALLOCATE. */
1540 static int
1546 {
1547 /* See if we have or want to preallocate stack space.
1549 If we would have to push a partially-in-regs parm
1550 before other stack parms, preallocate stack space instead.
1552 If the size of some parm is not a multiple of the required stack
1553 alignment, we must preallocate.
1555 If the total size of arguments that would otherwise create a copy in
1556 a temporary (such as a CALL) is more than half the total argument list
1557 size, preallocation is faster.
1559 Another reason to preallocate is if we have a machine (like the m88k)
1560 where stack alignment is required to be maintained between every
1561 pair of insns, not just when the call is made. However, we assume here
1562 that such machines either do not have push insns (and hence preallocation
1563 would occur anyway) or the problem is taken care of with
1564 PUSH_ROUNDING. */
1567 {
1573 {
1584 copy_to_evaluate_size
1586 }
1591 }
1593 }
1595 /* If we preallocated stack space, compute the address of each argument
1596 and store it into the ARGS array.
1598 We need not ensure it is a valid memory address here; it will be
1599 validized when it is used.
1601 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1603 static void
1606 rtx argblock;
1608 {
1610 {
1618 {
1621 rtx addr;
1623 /* Skip this parm if it will not be passed on the stack. */
1629 else
1640 else
1649 /* Function incoming arguments may overlap with sibling call
1650 outgoing arguments and we cannot allow reordering of reads
1651 from function arguments with stores to outgoing arguments
1652 of sibling calls. */
1655 }
1656 }
1657 }
1659 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1660 in a call instruction.
1662 FNDECL is the tree node for the target function. For an indirect call
1663 FNDECL will be NULL_TREE.
1665 ADDR is the operand 0 of CALL_EXPR for this call. */
1667 static rtx
1669 tree fndecl;
1670 tree addr;
1671 {
1672 rtx funexp;
1674 /* Get the function to call, in the form of RTL. */
1676 {
1677 /* If this is the first use of the function, see if we need to
1678 make an external definition for it. */
1680 {
1683 }
1685 /* Get a SYMBOL_REF rtx for the function address. */
1687 }
1688 else
1689 /* Generate an rtx (probably a pseudo-register) for the address. */
1690 {
1695 }
1697 }
1699 /* Do the register loads required for any wholly-register parms or any
1700 parms which are passed both on the stack and in a register. Their
1701 expressions were already evaluated.
1703 Mark all register-parms as living through the call, putting these USE
1704 insns in the CALL_INSN_FUNCTION_USAGE field.
1706 When IS_SIBCALL, perform the check_sibcall_overlap_argument_overlap
1707 checking, setting *SIBCALL_FAILURE if appropriate. */
1709 static void
1718 {
1721 #ifdef LOAD_ARGS_REVERSED
1723 #else
1725 #endif
1726 {
1733 {
1735 /* Set to non-negative if must move a word at a time, even if just
1736 one word (e.g, partial == 1 && mode == DFmode). Set to -1 if
1737 we just use a normal move insn. This value can be zero if the
1738 argument is a zero size structure with no fields. */
1745 /* Handle calls that pass values in multiple non-contiguous
1746 locations. The Irix 6 ABI has examples of this. */
1752 /* If simple case, just do move. If normal partial, store_one_arg
1753 has already loaded the register for us. In all other cases,
1754 load the register(s) from memory. */
1759 /* If we have pre-computed the values to put in the registers in
1760 the case of non-aligned structures, copy them in now. */
1772 /* When a parameter is a block, and perhaps in other cases, it is
1773 possible that it did a load from an argument slot that was
1774 already clobbered. */
1779 /* Handle calls that pass values in multiple non-contiguous
1780 locations. The Irix 6 ABI has examples of this. */
1785 else
1787 }
1788 }
1789 }
1791 /* Try to integrate function. See expand_inline_function for documentation
1792 about the parameters. */
1794 static rtx
1796 tree fndecl;
1797 tree actparms;
1798 rtx target;
1800 tree type;
1801 rtx structure_value_addr;
1802 {
1803 rtx temp;
1804 rtx before_call;
1809 #ifdef REG_PARM_STACK_SPACE
1810 #ifdef MAYBE_REG_PARM_STACK_SPACE
1812 #else
1814 #endif
1815 #endif
1823 structure_value_addr);
1827 /* If inlining succeeded, return. */
1829 {
1831 {
1832 /* If the outgoing argument list must be preserved, push
1833 the stack before executing the inlined function if it
1834 makes any calls. */
1840 ;
1843 {
1844 rtx first_insn
1848 /* Look for a call in the inline function code.
1849 If DECL_SAVED_INSNS (fndecl)->outgoing_args_size is
1850 nonzero then there is a call and it is not necessary
1851 to scan the insns. */
1859 {
1860 /* Reserve enough stack space so that the largest
1861 argument list of any function call in the inline
1862 function does not overlap the argument list being
1863 evaluated. This is usually an overestimate because
1864 allocate_dynamic_stack_space reserves space for an
1865 outgoing argument list in addition to the requested
1866 space, but there is no way to ask for stack space such
1867 that an argument list of a certain length can be
1868 safely constructed.
1870 Add the stack space reserved for register arguments, if
1871 any, in the inline function. What is really needed is the
1872 largest value of reg_parm_stack_space in the inline
1873 function, but that is not available. Using the current
1874 value of reg_parm_stack_space is wrong, but gives
1875 correct results on all supported machines. */
1888 }
1889 }
1890 }
1892 /* If the result is equivalent to TARGET, return TARGET to simplify
1893 checks in store_expr. They can be equivalent but not equal in the
1894 case of a function that returns BLKmode. */
1898 }
1900 /* If inlining failed, mark FNDECL as needing to be compiled
1901 separately after all. If function was declared inline,
1902 give a warning. */
1905 {
1908 }
1911 }
1913 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
1914 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
1915 bytes, then we would need to push some additional bytes to pad the
1916 arguments. So, we compute an adjust to the stack pointer for an
1917 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
1918 bytes. Then, when the arguments are pushed the stack will be perfectly
1919 aligned. ARGS_SIZE->CONSTANT is set to the number of bytes that should
1920 be popped after the call. Returns the adjustment. */
1922 static int
1924 args_size,
1925 preferred_unit_stack_boundary)
1929 {
1930 /* The number of bytes to pop so that the stack will be
1931 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
1932 HOST_WIDE_INT adjustment;
1933 /* The alignment of the stack after the arguments are pushed, if we
1934 just pushed the arguments without adjust the stack here. */
1935 HOST_WIDE_INT unadjusted_alignment;
1937 unadjusted_alignment
1941 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
1942 as possible -- leaving just enough left to cancel out the
1943 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
1944 PENDING_STACK_ADJUST is non-negative, and congruent to
1945 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
1947 /* Begin by trying to pop all the bytes. */
1948 unadjusted_alignment
1949 = (unadjusted_alignment
1952 /* Push enough additional bytes that the stack will be aligned
1953 after the arguments are pushed. */
1955 {
1958 else
1960 }
1962 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
1963 bytes after the call. The right number is the entire
1964 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
1965 by the arguments in the first place. */
1966 args_size->constant
1970 }
1972 /* Scan X expression if it does not dereference any argument slots
1973 we already clobbered by tail call arguments (as noted in stored_args_map
1974 bitmap).
1975 Return nonzero if X expression dereferences such argument slots,
1976 zero otherwise. */
1978 static int
1980 rtx x;
1981 {
1982 RTX_CODE code;
1993 {
1998 current_function_internal_arg_pointer
2001 else
2004 #ifdef ARGS_GROW_DOWNWARD
2006 #endif
2014 }
2016 /* Scan all subexpressions. */
2019 {
2021 {
2024 }
2026 {
2030 }
2031 }
2033 }
2035 /* Scan sequence after INSN if it does not dereference any argument slots
2036 we already clobbered by tail call arguments (as noted in stored_args_map
2037 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
2038 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
2039 should be 0). Return nonzero if sequence after INSN dereferences such argument
2040 slots, zero otherwise. */
2042 static int
2044 rtx insn;
2047 {
2052 else
2061 {
2062 #ifdef ARGS_GROW_DOWNWARD
2064 #else
2066 #endif
2070 }
2072 }
2074 static tree
2076 tree t;
2077 {
2079 {
2088 {
2094 }
2099 }
2101 }
2103 /* Generate all the code for a function call
2104 and return an rtx for its value.
2105 Store the value in TARGET (specified as an rtx) if convenient.
2106 If the value is stored in TARGET then TARGET is returned.
2107 If IGNORE is nonzero, then we ignore the value of the function call. */
2109 rtx
2111 tree exp;
2112 rtx target;
2114 {
2115 /* Nonzero if we are currently expanding a call. */
2118 /* List of actual parameters. */
2120 /* RTX for the function to be called. */
2121 rtx funexp;
2122 /* Sequence of insns to perform a tail recursive "call". */
2124 /* Sequence of insns to perform a normal "call". */
2126 /* Sequence of insns to perform a tail recursive "call". */
2128 /* Data type of the function. */
2129 tree funtype;
2130 /* Declaration of the function being called,
2131 or 0 if the function is computed (not known by name). */
2133 rtx insn;
2138 /* Register in which non-BLKmode value will be returned,
2139 or 0 if no value or if value is BLKmode. */
2140 rtx valreg;
2141 /* Address where we should return a BLKmode value;
2142 0 if value not BLKmode. */
2144 /* Nonzero if that address is being passed by treating it as
2145 an extra, implicit first parameter. Otherwise,
2146 it is passed by being copied directly into struct_value_rtx. */
2148 /* Size of aggregate value wanted, or zero if none wanted
2149 or if we are using the non-reentrant PCC calling convention
2150 or expecting the value in registers. */
2152 /* Nonzero if called function returns an aggregate in memory PCC style,
2153 by returning the address of where to find it. */
2156 /* Number of actual parameters in this call, including struct value addr. */
2158 /* Number of named args. Args after this are anonymous ones
2159 and they must all go on the stack. */
2162 /* Vector of information about each argument.
2163 Arguments are numbered in the order they will be pushed,
2164 not the order they are written. */
2167 /* Total size in bytes of all the stack-parms scanned so far. */
2170 /* Size of arguments before any adjustments (such as rounding). */
2172 /* Data on reg parms scanned so far. */
2173 CUMULATIVE_ARGS args_so_far;
2174 /* Nonzero if a reg parm has been scanned. */
2176 /* Nonzero if this is an indirect function call. */
2178 /* Nonzero if we must avoid push-insns in the args for this call.
2179 If stack space is allocated for register parameters, but not by the
2180 caller, then it is preallocated in the fixed part of the stack frame.
2181 So the entire argument block must then be preallocated (i.e., we
2182 ignore PUSH_ROUNDING in that case). */
2186 /* Size of the stack reserved for parameter registers. */
2189 /* Address of space preallocated for stack parms
2190 (on machines that lack push insns), or 0 if space not preallocated. */
2193 /* Mask of ECF_ flags. */
2195 /* Nonzero if this is a call to an inline function. */
2197 #ifdef REG_PARM_STACK_SPACE
2198 /* Define the boundary of the register parm stack space that needs to be
2199 saved, if any. */
2202 #endif
2209 /* State variables to track stack modifications. */
2215 /* Some stack pointer alterations we make are performed via
2216 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2217 which we then also need to save/restore along the way. */
2220 rtx call_fusage;
2224 /* The alignment of the stack, in bits. */
2225 HOST_WIDE_INT preferred_stack_boundary;
2226 /* The alignment of the stack, in bytes. */
2227 HOST_WIDE_INT preferred_unit_stack_boundary;
2229 /* See if this is "nothrow" function call. */
2233 /* See if we can find a DECL-node for the actual function.
2234 As a result, decide whether this is a call to an integrable function. */
2238 {
2246 {
2247 /* In case this function later becomes inlinable,
2248 record that there was already a non-inline call to it.
2250 Use abstraction instead of setting TREE_ADDRESSABLE
2251 directly. */
2254 {
2257 }
2259 }
2262 }
2264 /* If we don't have specific function to call, see if we have a
2265 attributes set in the type. */
2266 else
2269 #ifdef REG_PARM_STACK_SPACE
2270 #ifdef MAYBE_REG_PARM_STACK_SPACE
2272 #else
2274 #endif
2275 #endif
2277 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2280 #endif
2282 /* Warn if this value is an aggregate type,
2283 regardless of which calling convention we are using for it. */
2287 /* Set up a place to return a structure. */
2289 /* Cater to broken compilers. */
2291 {
2292 /* This call returns a big structure. */
2295 #ifdef PCC_STATIC_STRUCT_RETURN
2296 {
2298 /* Easier than making that case work right. */
2300 {
2301 /* In case this is a static function, note that it has been
2302 used. */
2306 }
2307 }
2309 {
2313 {
2314 /* The structure value address arg is already in actparms.
2315 Pull it out. It might be nice to just leave it there, but
2316 we need to set structure_value_addr. */
2321 }
2324 else
2325 {
2326 /* For variable-sized objects, we must be called with a target
2327 specified. If we were to allocate space on the stack here,
2328 we would have no way of knowing when to free it. */
2334 }
2335 }
2337 }
2339 /* If called function is inline, try to integrate it. */
2342 {
2345 structure_value_addr);
2348 }
2350 /* Figure out the amount to which the stack should be aligned. */
2353 {
2357 }
2359 /* Operand 0 is a pointer-to-function; get the type of the function. */
2365 /* See if this is a call to a function that can return more than once
2366 or a call to longjmp or malloc. */
2372 /* If struct_value_rtx is 0, it means pass the address
2373 as if it were an extra parameter. */
2375 {
2376 /* If structure_value_addr is a REG other than
2377 virtual_outgoing_args_rtx, we can use always use it. If it
2378 is not a REG, we must always copy it into a register.
2379 If it is virtual_outgoing_args_rtx, we must copy it to another
2380 register in some cases. */
2382 || (ACCUMULATE_OUTGOING_ARGS
2383 && stack_arg_under_construction
2388 actparms
2391 temp),
2392 actparms);
2394 }
2396 /* Count the arguments and set NUM_ACTUALS. */
2398 num_actuals++;
2400 /* Compute number of named args.
2401 Normally, don't include the last named arg if anonymous args follow.
2402 We do include the last named arg if STRICT_ARGUMENT_NAMING is nonzero.
2403 (If no anonymous args follow, the result of list_length is actually
2404 one too large. This is harmless.)
2406 If PRETEND_OUTGOING_VARARGS_NAMED is set and STRICT_ARGUMENT_NAMING is
2407 zero, this machine will be able to place unnamed args that were
2408 passed in registers into the stack. So treat all args as named.
2409 This allows the insns emitting for a specific argument list to be
2410 independent of the function declaration.
2412 If PRETEND_OUTGOING_VARARGS_NAMED is not set, we do not have any
2413 reliable way to pass unnamed args in registers, so we must force
2414 them into memory. */
2419 n_named_args
2421 /* Don't include the last named arg. */
2423 /* Count the struct value address, if it is passed as a parm. */
2425 else
2426 /* If we know nothing, treat all args as named. */
2429 /* Start updating where the next arg would go.
2431 On some machines (such as the PA) indirect calls have a different
2432 calling convention than normal calls. The last argument in
2433 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2434 or not. */
2437 /* Make a vector to hold all the information about each arg. */
2441 /* Build up entries in the ARGS array, compute the size of the
2442 arguments into ARGS_SIZE, etc. */
2450 {
2451 /* If this function requires a variable-sized argument list, don't
2452 try to make a cse'able block for this call. We may be able to
2453 do this eventually, but it is too complicated to keep track of
2454 what insns go in the cse'able block and which don't. */
2458 }
2460 /* Now make final decision about preallocating stack space. */
2465 /* If the structure value address will reference the stack pointer, we
2466 must stabilize it. We don't need to do this if we know that we are
2467 not going to adjust the stack pointer in processing this call. */
2472 structure_value_addr))
2477 /* Tail calls can make things harder to debug, and we're traditionally
2478 pushed these optimizations into -O2. Don't try if we're already
2479 expanding a call, as that means we're an argument. Don't try if
2480 there's cleanups, as we know there's code to follow the call.
2482 If rtx_equal_function_value_matters is false, that means we've
2483 finished with regular parsing. Which means that some of the
2484 machinery we use to generate tail-calls is no longer in place.
2485 This is most often true of sjlj-exceptions, which we couldn't
2486 tail-call to anyway. */
2489 || !flag_optimize_sibling_calls
2490 || !rtx_equal_function_value_matters
2495 /* Tail recursion fails, when we are not dealing with recursive calls. */
2501 /* Rest of purposes for tail call optimizations to fail. */
2503 #ifdef HAVE_sibcall_epilogue
2504 !HAVE_sibcall_epilogue
2505 #else
2506 1
2507 #endif
2508 || !try_tail_call
2509 /* Doing sibling call optimization needs some work, since
2510 structure_value_addr can be allocated on the stack.
2511 It does not seem worth the effort since few optimizable
2512 sibling calls will return a structure. */
2514 /* Check whether the target is able to optimize the call
2515 into a sibcall. */
2517 /* Functions that do not return exactly once may not be sibcall
2518 optimized. */
2521 /* If the called function is nested in the current one, it might access
2522 some of the caller's arguments, but could clobber them beforehand if
2523 the argument areas are shared. */
2525 /* If this function requires more stack slots than the current
2526 function, we cannot change it into a sibling call. */
2528 /* If the callee pops its own arguments, then it must pop exactly
2529 the same number of arguments as the current function. */
2533 current_function_args_size))
2537 {
2540 /* Ok, we're going to give the tail call the old college try.
2541 This means we're going to evaluate the function arguments
2542 up to three times. There are two degrees of badness we can
2543 encounter, those that can be unsaved and those that can't.
2544 (See unsafe_for_reeval commentary for details.)
2546 Generate a new argument list. Pass safe arguments through
2547 unchanged. For the easy badness wrap them in UNSAVE_EXPRs.
2548 For hard badness, evaluate them now and put their resulting
2549 rtx in a temporary VAR_DECL.
2551 initialize_argument_information has ordered the array for the
2552 order to be pushed, and we must remember this when reconstructing
2553 the original argument order. */
2556 {
2560 }
2561 else
2562 {
2566 }
2569 {
2571 /* We need to build actparms for optimize_tail_recursion. We can
2572 safely trash away TREE_PURPOSE, since it is unused by this
2573 function. */
2576 }
2577 /* Do the same for the function address if it is an expression. */
2580 /* Expanding one of those dangerous arguments could have added
2581 cleanups, but otherwise give it a whirl. */
2584 }
2586 /* Generate a tail recursion sequence when calling ourselves. */
2589 {
2590 /* We want to emit any pending stack adjustments before the tail
2591 recursion "call". That way we know any adjustment after the tail
2592 recursion call can be ignored if we indeed use the tail recursion
2593 call expansion. */
2597 /* Emit any queued insns now; otherwise they would end up in
2598 only one of the alternates. */
2601 /* Use a new sequence to hold any RTL we generate. We do not even
2602 know if we will use this RTL yet. The final decision can not be
2603 made until after RTL generation for the entire function is
2604 complete. */
2606 /* If expanding any of the arguments creates cleanups, we can't
2607 do a tailcall. So, we'll need to pop the pending cleanups
2608 list. If, however, all goes well, and there are no cleanups
2609 then the call to expand_start_target_temps will have no
2610 effect. */
2613 {
2616 else
2618 }
2622 /* Restore the original pending stack adjustment for the sibling and
2623 normal call cases below. */
2626 }
2629 {
2630 /* A fork duplicates the profile information, and an exec discards
2631 it. We can't rely on fork/exec to be paired. So write out the
2632 profile information we have gathered so far, and clear it. */
2633 /* ??? When Linux's __clone is called with CLONE_VM set, profiling
2634 is subject to race conditions, just as with multithreaded
2635 programs. */
2638 }
2640 /* Ensure current function's preferred stack boundary is at least
2641 what we need. We don't have to increase alignment for recursive
2642 functions. */
2651 function_call_count++;
2653 /* We want to make two insn chains; one for a sibling call, the other
2654 for a normal call. We will select one of the two chains after
2655 initial RTL generation is complete. */
2657 {
2659 /* We want to emit any pending stack adjustments before the tail
2660 recursion "call". That way we know any adjustment after the tail
2661 recursion call can be ignored if we indeed use the tail recursion
2662 call expansion. */
2665 rtx insns;
2669 {
2670 /* Emit any queued insns now; otherwise they would end up in
2671 only one of the alternates. */
2674 /* State variables we need to save and restore between
2675 iterations. */
2678 }
2681 else
2684 /* Other state variables that we must reinitialize each time
2685 through the loop (that are not initialized by the loop itself). */
2689 /* Start a new sequence for the normal call case.
2691 From this point on, if the sibling call fails, we want to set
2692 sibcall_failure instead of continuing the loop. */
2696 {
2697 /* We know at this point that there are not currently any
2698 pending cleanups. If, however, in the process of evaluating
2699 the arguments we were to create some, we'll need to be
2700 able to get rid of them. */
2702 }
2704 /* Don't let pending stack adjusts add up to too much.
2705 Also, do all pending adjustments now if there is any chance
2706 this might be a call to alloca or if we are expanding a sibling
2707 call sequence or if we are calling a function that is to return
2708 with stack pointer depressed. */
2715 /* When calling a const function, we must pop the stack args right away,
2716 so that the pop is deleted or moved with the call. */
2718 NO_DEFER_POP;
2720 #ifdef FINAL_REG_PARM_STACK_SPACE
2723 #endif
2724 /* Precompute any arguments as needed. */
2728 /* Now we are about to start emitting insns that can be deleted
2729 if a libcall is deleted. */
2734 /* Compute the actual size of the argument block required. The variable
2735 and constant sizes must be combined, the size may have to be rounded,
2736 and there may be a minimum required size. When generating a sibcall
2737 pattern, do not round up, since we'll be re-using whatever space our
2738 caller provided. */
2739 unadjusted_args_size
2747 /* The argument block when performing a sibling call is the
2748 incoming argument block. */
2750 {
2752 argblock
2753 #ifdef STACK_GROWS_DOWNWARD
2755 #else
2757 #endif
2760 }
2762 /* If we have no actual push instructions, or shouldn't use them,
2763 make space for all args right now. */
2765 {
2767 {
2772 /* stack_arg_under_construction says whether a stack arg is
2773 being constructed at the old stack level. Pushing the stack
2774 gets a clean outgoing argument block. */
2777 }
2779 }
2780 else
2781 {
2782 /* Note that we must go through the motions of allocating an argument
2783 block even if the size is zero because we may be storing args
2784 in the area reserved for register arguments, which may be part of
2785 the stack frame. */
2789 /* Store the maximum argument space used. It will be pushed by
2790 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2791 checking). */
2797 {
2799 {
2800 /* Since the stack pointer will never be pushed, it is
2801 possible for the evaluation of a parm to clobber
2802 something we have already written to the stack.
2803 Since most function calls on RISC machines do not use
2804 the stack, this is uncommon, but must work correctly.
2806 Therefore, we save any area of the stack that was already
2807 written and that we are using. Here we set up to do this
2808 by making a new stack usage map from the old one. The
2809 actual save will be done by store_one_arg.
2811 Another approach might be to try to reorder the argument
2812 evaluations to avoid this conflicting stack usage. */
2814 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2815 /* Since we will be writing into the entire argument area,
2816 the map must be allocated for its entire size, not just
2817 the part that is the responsibility of the caller. */
2819 #endif
2821 #ifdef ARGS_GROW_DOWNWARD
2824 #else
2826 needed);
2827 #endif
2828 stack_usage_map
2833 initial_highest_arg_in_use);
2837 (highest_outgoing_arg_in_use
2841 /* The address of the outgoing argument list must not be
2842 copied to a register here, because argblock would be left
2843 pointing to the wrong place after the call to
2844 allocate_dynamic_stack_space below. */
2847 }
2848 else
2849 {
2851 {
2852 /* Try to reuse some or all of the pending_stack_adjust
2853 to get this space. */
2854 needed
2855 = (combine_pending_stack_adjustment_and_call
2858 preferred_unit_stack_boundary));
2860 /* combine_pending_stack_adjustment_and_call computes
2861 an adjustment before the arguments are allocated.
2862 Account for them and see whether or not the stack
2863 needs to go up or down. */
2867 {
2868 /* We're releasing stack space. */
2869 /* ??? We can avoid any adjustment at all if we're
2870 already aligned. FIXME. */
2874 }
2875 else
2876 /* We need to allocate space. We'll do that in
2877 push_block below. */
2879 }
2881 /* Special case this because overhead of `push_block' in
2882 this case is non-trivial. */
2885 else
2888 /* We only really need to call `copy_to_reg' in the case
2889 where push insns are going to be used to pass ARGBLOCK
2890 to a function call in ARGS. In that case, the stack
2891 pointer changes value from the allocation point to the
2892 call point, and hence the value of
2893 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2894 as well always do it. */
2896 }
2897 }
2898 }
2901 {
2902 /* The save/restore code in store_one_arg handles all
2903 cases except one: a constructor call (including a C
2904 function returning a BLKmode struct) to initialize
2905 an argument. */
2907 {
2908 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2911 #else
2913 #endif
2915 {
2917 NULL_RTX);
2921 /* stack_arg_under_construction says whether a stack
2922 arg is being constructed at the old stack level.
2923 Pushing the stack gets a clean outgoing argument
2924 block. */
2925 old_stack_arg_under_construction
2928 /* Make a new map for the new argument list. */
2933 }
2935 BITS_PER_UNIT);
2936 }
2938 /* If argument evaluation might modify the stack pointer,
2939 copy the address of the argument list to a register. */
2942 {
2945 }
2946 }
2950 /* If we push args individually in reverse order, perform stack alignment
2951 before the first push (the last arg). */
2954 {
2955 /* When the stack adjustment is pending, we get better code
2956 by combining the adjustments. */
2960 {
2961 pending_stack_adjust
2962 = (combine_pending_stack_adjustment_and_call
2965 preferred_unit_stack_boundary));
2967 }
2971 }
2972 /* Now that the stack is properly aligned, pops can't safely
2973 be deferred during the evaluation of the arguments. */
2974 NO_DEFER_POP;
2978 /* Figure out the register where the value, if any, will come back. */
2982 {
2986 else
2988 }
2990 /* Precompute all register parameters. It isn't safe to compute anything
2991 once we have started filling any specific hard regs. */
2994 #ifdef REG_PARM_STACK_SPACE
2995 /* Save the fixed argument area if it's part of the caller's frame and
2996 is clobbered by argument setup for this call. */
3000 #endif
3002 /* Now store (and compute if necessary) all non-register parms.
3003 These come before register parms, since they can require block-moves,
3004 which could clobber the registers used for register parms.
3005 Parms which have partial registers are not stored here,
3006 but we do preallocate space here if they want that. */
3010 {
3015 reg_parm_stack_space)
3020 }
3022 /* If we have a parm that is passed in registers but not in memory
3023 and whose alignment does not permit a direct copy into registers,
3024 make a group of pseudos that correspond to each register that we
3025 will later fill. */
3029 /* Now store any partially-in-registers parm.
3030 This is the last place a block-move can happen. */
3034 {
3039 reg_parm_stack_space)
3044 }
3046 /* If we pushed args in forward order, perform stack alignment
3047 after pushing the last arg. */
3052 /* If register arguments require space on the stack and stack space
3053 was not preallocated, allocate stack space here for arguments
3054 passed in registers. */
3055 #ifdef OUTGOING_REG_PARM_STACK_SPACE
3059 #endif
3061 /* Pass the function the address in which to return a
3062 structure value. */
3064 {
3068 NULL_RTX)));
3072 }
3080 /* Perform postincrements before actually calling the function. */
3083 /* Save a pointer to the last insn before the call, so that we can
3084 later safely search backwards to find the CALL_INSN. */
3087 /* Set up next argument register. For sibling calls on machines
3088 with register windows this should be the incoming register. */
3089 #ifdef FUNCTION_INCOMING_ARG
3093 else
3094 #endif
3098 /* All arguments and registers used for the call must be set up by
3099 now! */
3101 /* Stack must be properly aligned now. */
3105 /* Generate the actual call instruction. */
3111 /* If call is cse'able, make appropriate pair of reg-notes around it.
3112 Test valreg so we don't crash; may safely ignore `const'
3113 if return type is void. Disable for PARALLEL return values, because
3114 we have no way to move such values into a pseudo register. */
3116 {
3117 rtx insns;
3120 {
3124 }
3125 else
3126 {
3130 /* Mark the return value as a pointer if needed. */
3135 /* Construct an "equal form" for the value which mentions all the
3136 arguments in order as well as the function name. */
3150 note);
3155 }
3156 }
3158 {
3162 /* The return value from a malloc-like function is a pointer. */
3168 /* The return value from a malloc-like function can not alias
3169 anything else. */
3174 /* Write out the sequence. */
3179 }
3181 /* For calls to `setjmp', etc., inform flow.c it should complain
3182 if nonvolatile values are live. For functions that cannot return,
3183 inform flow that control does not fall through. */
3186 {
3187 /* The barrier must be emitted
3188 immediately after the CALL_INSN. Some ports emit more
3189 than just a CALL_INSN above, so we must search for it here. */
3193 {
3195 /* There was no CALL_INSN? */
3198 }
3201 }
3206 /* If this function is returning into a memory location marked as
3207 readonly, it means it is initializing that location. But we normally
3208 treat functions as not clobbering such locations, so we need to
3209 specify that this one does. */
3214 /* If value type not void, return an rtx for the value. */
3216 /* If there are cleanups to be called, don't use a hard reg as target.
3217 We need to double check this and see if it matters anymore. */
3219 {
3224 }
3230 {
3232 {
3233 target
3236 structure_value_addr));
3238 }
3239 }
3241 {
3242 /* This is the special C++ case where we need to
3243 know what the true target was. We take care to
3244 never use this value more than once in one expression. */
3248 }
3249 /* Handle calls that return values in multiple non-contiguous locations.
3250 The Irix 6 ABI has examples of this. */
3252 {
3254 {
3255 /* This will only be assigned once, so it can be readonly. */
3262 }
3268 /* We can not support sibling calls for this case. */
3270 }
3274 {
3275 /* TARGET and VALREG cannot be equal at this point because the
3276 latter would not have REG_FUNCTION_VALUE_P true, while the
3277 former would if it were referring to the same register.
3279 If they refer to the same register, this move will be a no-op,
3280 except when function inlining is being done. */
3282 }
3284 {
3287 /* We can not support sibling calls for this case. */
3289 }
3290 else
3293 #ifdef PROMOTE_FUNCTION_RETURN
3294 /* If we promoted this return value, make the proper SUBREG. TARGET
3295 might be const0_rtx here, so be careful. */
3299 {
3304 /* If we don't promote as expected, something is wrong. */
3312 {
3319 }
3323 }
3324 #endif
3326 /* If size of args is variable or this was a constructor call for a stack
3327 argument, restore saved stack-pointer value. */
3330 {
3338 }
3340 {
3341 #ifdef REG_PARM_STACK_SPACE
3345 #endif
3347 /* If we saved any argument areas, restore them. */
3350 {
3352 rtx stack_area
3359 else
3362 BLOCK_OP_CALL_PARM);
3363 }
3367 }
3369 /* If this was alloca, record the new stack level for nonlocal gotos.
3370 Check for the handler slots since we might not have a save area
3371 for non-local gotos. */
3376 /* Free up storage we no longer need. */
3382 {
3383 /* Undo the fake expand_start_target_temps we did earlier. If
3384 there had been any cleanups created, we've already set
3385 sibcall_failure. */
3387 }
3393 {
3396 /* Restore the pending stack adjustment now that we have
3397 finished generating the sibling call sequence. */
3402 /* Prepare arg structure for next iteration. */
3404 {
3408 }
3411 }
3412 else
3413 {
3416 /* Verify that we've deallocated all the stack we used. */
3420 }
3422 /* If something prevents making this a sibling call,
3423 zero out the sequence. */
3426 }
3428 /* The function optimize_sibling_and_tail_recursive_calls doesn't
3429 handle CALL_PLACEHOLDERs inside other CALL_PLACEHOLDERs. This
3430 can happen if the arguments to this function call an inline
3431 function who's expansion contains another CALL_PLACEHOLDER.
3433 If there are any C_Ps in any of these sequences, replace them
3434 with their normal call. */
3451 /* If this was a potential tail recursion site, then emit a
3452 CALL_PLACEHOLDER with the normal and the tail recursion streams.
3453 One of them will be selected later. */
3455 {
3456 /* The tail recursion label must be kept around. We could expose
3457 its use in the CALL_PLACEHOLDER, but that creates unwanted edges
3458 and makes determining true tail recursion sites difficult.
3460 So we set LABEL_PRESERVE_P here, then clear it when we select
3461 one of the call sequences after rtl generation is complete. */
3465 tail_call_insns,
3466 tail_recursion_insns,
3467 tail_recursion_label));
3468 }
3469 else
3472 currently_expanding_call--;
3474 /* If this function returns with the stack pointer depressed, ensure
3475 this block saves and restores the stack pointer, show it was
3476 changed, and adjust for any outgoing arg space. */
3478 {
3483 }
3486 }
3487 \f
3488 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3489 The RETVAL parameter specifies whether return value needs to be saved, other
3490 parameters are documented in the emit_library_call function below. */
3492 static rtx
3495 rtx orgfun;
3496 rtx value;
3501 {
3502 /* Total size in bytes of all the stack-parms scanned so far. */
3504 /* Size of arguments before any adjustments (such as rounding). */
3507 rtx fun;
3512 CUMULATIVE_ARGS args_so_far;
3513 struct arg
3514 {
3515 rtx value;
3517 rtx reg;
3521 rtx save_area;
3522 };
3527 rtx valreg;
3533 rtx before_call;
3536 #ifdef REG_PARM_STACK_SPACE
3537 /* Define the boundary of the register parm stack space that needs to be
3538 save, if any. */
3541 #endif
3543 /* Size of the stack reserved for parameter registers. */
3547 #ifdef REG_PARM_STACK_SPACE
3548 #ifdef MAYBE_REG_PARM_STACK_SPACE
3550 #else
3552 #endif
3553 #endif
3555 /* By default, library functions can not throw. */
3559 {
3586 }
3589 /* Ensure current function's preferred stack boundary is at least
3590 what we need. */
3594 /* If this kind of value comes back in memory,
3595 decide where in memory it should come back. */
3597 {
3600 {
3601 #ifdef PCC_STATIC_STRUCT_RETURN
3602 rtx pointer_reg
3612 else
3614 #endif
3615 /* This call returns a big structure. */
3617 }
3618 }
3619 else
3622 /* ??? Unfinished: must pass the memory address as an argument. */
3624 /* Copy all the libcall-arguments out of the varargs data
3625 and into a vector ARGVEC.
3627 Compute how to pass each argument. We only support a very small subset
3628 of the full argument passing conventions to limit complexity here since
3629 library functions shouldn't have many args. */
3634 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3636 #else
3638 #endif
3645 /* Now we are about to start emitting insns that can be deleted
3646 if a libcall is deleted. */
3652 /* If there's a structure value address to be passed,
3653 either pass it in the special place, or pass it as an extra argument. */
3655 {
3657 nargs++;
3659 /* Make sure it is a reasonable operand for a move or push insn. */
3669 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3672 #endif
3675 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3677 #else
3679 #endif
3689 count++;
3690 }
3693 {
3697 /* We cannot convert the arg value to the mode the library wants here;
3698 must do it earlier where we know the signedness of the arg. */
3703 /* On some machines, there's no way to pass a float to a library fcn.
3704 Pass it as a double instead. */
3705 #ifdef LIBGCC_NEEDS_DOUBLE
3708 #endif
3710 /* There's no need to call protect_from_queue, because
3711 either emit_move_insn or emit_push_insn will do that. */
3713 /* Make sure it is a reasonable operand for a move or push insn. */
3718 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
3720 {
3721 rtx slot;
3723 #ifdef FUNCTION_ARG_CALLEE_COPIES
3726 #endif
3727 ;
3729 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3730 functions, so we have to pretend this isn't such a function. */
3732 {
3736 }
3739 /* If this was a CONST function, it is now PURE since
3740 it now reads memory. */
3742 {
3745 }
3750 {
3754 }
3755 else
3756 {
3759 slot
3765 }
3769 call_fusage);
3773 slot),
3774 call_fusage);
3778 }
3779 #endif
3786 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3789 #else
3791 #endif
3794 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3796 #else
3798 #endif
3813 }
3815 #ifdef FINAL_REG_PARM_STACK_SPACE
3818 #endif
3819 /* If this machine requires an external definition for library
3820 functions, write one out. */
3825 + stack_pointer_delta
3827 / STACK_BYTES
3832 reg_parm_stack_space);
3834 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3836 #endif
3842 {
3843 /* Since the stack pointer will never be pushed, it is possible for
3844 the evaluation of a parm to clobber something we have already
3845 written to the stack. Since most function calls on RISC machines
3846 do not use the stack, this is uncommon, but must work correctly.
3848 Therefore, we save any area of the stack that was already written
3849 and that we are using. Here we set up to do this by making a new
3850 stack usage map from the old one.
3852 Another approach might be to try to reorder the argument
3853 evaluations to avoid this conflicting stack usage. */
3857 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3858 /* Since we will be writing into the entire argument area, the
3859 map must be allocated for its entire size, not just the part that
3860 is the responsibility of the caller. */
3862 #endif
3864 #ifdef ARGS_GROW_DOWNWARD
3867 #else
3869 needed);
3870 #endif
3875 initial_highest_arg_in_use);
3882 /* We must be careful to use virtual regs before they're instantiated,
3883 and real regs afterwards. Loop optimization, for example, can create
3884 new libcalls after we've instantiated the virtual regs, and if we
3885 use virtuals anyway, they won't match the rtl patterns. */
3889 else
3891 }
3892 else
3893 {
3896 }
3898 /* If we push args individually in reverse order, perform stack alignment
3899 before the first push (the last arg). */
3905 {
3908 }
3909 else
3910 {
3913 }
3915 #ifdef REG_PARM_STACK_SPACE
3917 {
3918 /* The argument list is the property of the called routine and it
3919 may clobber it. If the fixed area has been used for previous
3920 parameters, we must save and restore it. */
3923 }
3924 #endif
3926 /* Push the args that need to be pushed. */
3928 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
3929 are to be pushed. */
3931 {
3939 {
3941 {
3942 /* If this is being stored into a pre-allocated, fixed-size,
3943 stack area, save any previous data at that location. */
3945 #ifdef ARGS_GROW_DOWNWARD
3946 /* stack_slot is negative, but we want to index stack_usage_map
3947 with positive values. */
3950 #else
3953 #endif
3956 /* Don't worry about things in the fixed argument area;
3957 it has already been saved. */
3961 i++;
3964 {
3965 /* We need to make a save area. See what mode we can make
3966 it. */
3967 enum machine_mode save_mode
3971 rtx stack_area
3972 = gen_rtx_MEM
3974 memory_address
3981 }
3982 }
3989 /* Now mark the segment we just used. */
3994 NO_DEFER_POP;
3995 }
3996 }
3998 /* If we pushed args in forward order, perform stack alignment
3999 after pushing the last arg. */
4006 else
4011 /* Now load any reg parms into their regs. */
4013 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4014 are to be pushed. */
4016 {
4021 /* Handle calls that pass values in multiple non-contiguous
4022 locations. The PA64 has examples of this for library calls. */
4028 NO_DEFER_POP;
4029 }
4031 /* Any regs containing parms remain in use through the call. */
4033 {
4039 }
4041 /* Pass the function the address in which to return a structure value. */
4043 {
4047 NULL_RTX)));
4050 }
4052 /* Don't allow popping to be deferred, since then
4053 cse'ing of library calls could delete a call and leave the pop. */
4054 NO_DEFER_POP;
4058 /* Stack must be properly aligned now. */
4064 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4065 will set inhibit_defer_pop to that value. */
4066 /* The return type is needed to decide how many bytes the function pops.
4067 Signedness plays no role in that, so for simplicity, we pretend it's
4068 always signed. We also assume that the list of arguments passed has
4069 no impact, so we pretend it is unknown. */
4075 struct_value_size,
4077 valreg,
4080 /* For calls to `setjmp', etc., inform flow.c it should complain
4081 if nonvolatile values are live. For functions that cannot return,
4082 inform flow that control does not fall through. */
4085 {
4086 /* The barrier note must be emitted
4087 immediately after the CALL_INSN. Some ports emit more than
4088 just a CALL_INSN above, so we must search for it here. */
4092 {
4094 /* There was no CALL_INSN? */
4097 }
4100 }
4102 /* Now restore inhibit_defer_pop to its actual original value. */
4103 OK_DEFER_POP;
4105 /* If call is cse'able, make appropriate pair of reg-notes around it.
4106 Test valreg so we don't crash; may safely ignore `const'
4107 if return type is void. Disable for PARALLEL return values, because
4108 we have no way to move such values into a pseudo register. */
4110 {
4111 rtx insns;
4114 {
4118 }
4119 else
4120 {
4122 rtx temp;
4126 {
4130 }
4134 /* Construct an "equal form" for the value which mentions all the
4135 arguments in order as well as the function name. */
4148 note);
4153 }
4154 }
4157 /* Copy the value to the right place. */
4159 {
4161 {
4166 }
4168 {
4172 }
4175 else
4177 }
4180 {
4181 #ifdef REG_PARM_STACK_SPACE
4185 #endif
4187 /* If we saved any argument areas, restore them. */
4190 {
4192 rtx stack_area
4194 memory_address
4200 }
4204 }
4208 }
4209 \f
4210 /* Output a library call to function FUN (a SYMBOL_REF rtx)
4211 (emitting the queue unless NO_QUEUE is nonzero),
4212 for a value of mode OUTMODE,
4213 with NARGS different arguments, passed as alternating rtx values
4214 and machine_modes to convert them to.
4215 The rtx values should have been passed through protect_from_queue already.
4217 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
4218 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
4219 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
4220 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
4221 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
4222 or other LCT_ value for other types of library calls. */
4224 void
4227 {
4237 }
4238 \f
4239 /* Like emit_library_call except that an extra argument, VALUE,
4240 comes second and says where to store the result.
4241 (If VALUE is zero, this function chooses a convenient way
4242 to return the value.
4244 This function returns an rtx for where the value is to be found.
4245 If VALUE is nonzero, VALUE is returned. */
4247 rtx
4251 {
4252 rtx result;
4267 }
4268 \f
4269 /* Store a single argument for a function call
4270 into the register or memory area where it must be passed.
4271 *ARG describes the argument value and where to pass it.
4273 ARGBLOCK is the address of the stack-block for all the arguments,
4274 or 0 on a machine where arguments are pushed individually.
4276 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4277 so must be careful about how the stack is used.
4279 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4280 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4281 that we need not worry about saving and restoring the stack.
4283 FNDECL is the declaration of the function we are calling.
4285 Return nonzero if this arg should cause sibcall failure,
4286 zero otherwise. */
4288 static int
4291 rtx argblock;
4295 {
4306 /* Push a new temporary level for any temporaries we make for
4307 this argument. */
4311 {
4312 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4313 save any previous data at that location. */
4315 {
4316 #ifdef ARGS_GROW_DOWNWARD
4317 /* stack_slot is negative, but we want to index stack_usage_map
4318 with positive values. */
4321 else
4325 #else
4328 else
4332 #endif
4335 /* Don't worry about things in the fixed argument area;
4336 it has already been saved. */
4340 i++;
4343 {
4344 /* We need to make a save area. See what mode we can make it. */
4345 enum machine_mode save_mode
4347 rtx stack_area
4353 {
4362 BLOCK_OP_CALL_PARM);
4363 }
4364 else
4365 {
4368 }
4369 }
4370 }
4371 }
4373 /* If this isn't going to be placed on both the stack and in registers,
4374 set up the register and number of words. */
4376 {
4379 else
4382 }
4385 /* Being passed entirely in a register. We shouldn't be called in
4386 this case. */
4389 /* If this arg needs special alignment, don't load the registers
4390 here. */
4394 /* If this is being passed partially in a register, we can't evaluate
4395 it directly into its stack slot. Otherwise, we can. */
4397 {
4398 /* stack_arg_under_construction is nonzero if a function argument is
4399 being evaluated directly into the outgoing argument list and
4400 expand_call must take special action to preserve the argument list
4401 if it is called recursively.
4403 For scalar function arguments stack_usage_map is sufficient to
4404 determine which stack slots must be saved and restored. Scalar
4405 arguments in general have pass_on_stack == 0.
4407 If this argument is initialized by a function which takes the
4408 address of the argument (a C++ constructor or a C function
4409 returning a BLKmode structure), then stack_usage_map is
4410 insufficient and expand_call must push the stack around the
4411 function call. Such arguments have pass_on_stack == 1.
4413 Note that it is always safe to set stack_arg_under_construction,
4414 but this generates suboptimal code if set when not needed. */
4417 stack_arg_under_construction++;
4420 (partial
4425 /* If we are promoting object (or for any other reason) the mode
4426 doesn't agree, convert the mode. */
4433 stack_arg_under_construction--;
4434 }
4436 /* Don't allow anything left on stack from computation
4437 of argument to alloca. */
4442 /* If the value is already in the stack slot, we are done. */
4443 ;
4445 {
4448 /* Argument is a scalar, not entirely passed in registers.
4449 (If part is passed in registers, arg->partial says how much
4450 and emit_push_insn will take care of putting it there.)
4452 Push it, and if its size is less than the
4453 amount of space allocated to it,
4454 also bump stack pointer by the additional space.
4455 Note that in C the default argument promotions
4456 will prevent such mismatches. */
4459 /* Compute how much space the push instruction will push.
4460 On many machines, pushing a byte will advance the stack
4461 pointer by a halfword. */
4462 #ifdef PUSH_ROUNDING
4464 #endif
4467 /* Compute how much space the argument should get:
4468 round up to a multiple of the alignment for arguments. */
4474 /* This isn't already where we want it on the stack, so put it there.
4475 This can either be done with push or copy insns. */
4481 /* Unless this is a partially-in-register argument, the argument is now
4482 in the stack. */
4485 }
4486 else
4487 {
4488 /* BLKmode, at least partly to be pushed. */
4492 rtx size_rtx;
4494 /* Pushing a nonscalar.
4495 If part is passed in registers, PARTIAL says how much
4496 and emit_push_insn will take care of putting it there. */
4498 /* Round its size up to a multiple
4499 of the allocation unit for arguments. */
4502 {
4505 }
4506 else
4507 {
4508 /* PUSH_ROUNDING has no effect on us, because
4509 emit_push_insn for BLKmode is careful to avoid it. */
4514 }
4516 /* Some types will require stricter alignment, which will be
4517 provided for elsewhere in argument layout. */
4520 /* When an argument is padded down, the block is aligned to
4521 PARM_BOUNDARY, but the actual argument isn't. */
4523 {
4527 {
4530 }
4531 }
4534 {
4535 /* emit_push_insn might not work properly if arg->value and
4536 argblock + arg->offset areas overlap. */
4543 current_function_internal_arg_pointer
4545 {
4549 /* expand_call should ensure this */
4554 {
4557 }
4559 {
4562 }
4563 }
4564 }
4571 /* Unless this is a partially-in-register argument, the argument is now
4572 in the stack.
4574 ??? Unlike the case above, in which we want the actual
4575 address of the data, so that we can load it directly into a
4576 register, here we want the address of the stack slot, so that
4577 it's properly aligned for word-by-word copying or something
4578 like that. It's not clear that this is always correct. */
4581 }
4583 /* Mark all slots this store used. */
4589 /* Once we have pushed something, pops can't safely
4590 be deferred during the rest of the arguments. */
4591 NO_DEFER_POP;
4593 /* ANSI doesn't require a sequence point here,
4594 but PCC has one, so this will avoid some problems. */
4597 /* Free any temporary slots made in processing this argument. Show
4598 that we might have taken the address of something and pushed that
4599 as an operand. */
4605 }
4607 /* Nonzero if we do not know how to pass TYPE solely in registers.
4608 We cannot do so in the following cases:
4610 - if the type has variable size
4611 - if the type is marked as addressable (it is required to be constructed
4612 into the stack)
4613 - if the padding and mode of the type is such that a copy into a register
4614 would put it into the wrong part of the register.
4616 Which padding can't be supported depends on the byte endianness.
4618 A value in a register is implicitly padded at the most significant end.
4619 On a big-endian machine, that is the lower end in memory.
4620 So a value padded in memory at the upper end can't go in a register.
4621 For a little-endian machine, the reverse is true. */
4623 bool
4626 tree type;
4627 {
4631 /* If the type has variable size... */
4635 /* If the type is marked as addressable (it is required
4636 to be constructed into the stack)... */
4640 /* If the padding and mode of the type is such that a copy into
4641 a register would put it into the wrong part of the register. */
4649 }