| blob | 86e51842cf5a50772c0ba00c58cce3ccabfbc6f7 |
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, 2004 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. */
44 /* Like PREFERRED_STACK_BOUNDARY but in units of bytes, not bits. */
45 #define STACK_BYTES (PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT)
47 /* Data structure and subroutines used within expand_call. */
49 struct arg_data
50 {
51 /* Tree node for this argument. */
52 tree tree_value;
53 /* Mode for value; TYPE_MODE unless promoted. */
55 /* Current RTL value for argument, or 0 if it isn't precomputed. */
56 rtx value;
57 /* Initially-compute RTL value for argument; only for const functions. */
58 rtx initial_value;
59 /* Register to pass this argument in, 0 if passed on stack, or an
60 PARALLEL if the arg is to be copied into multiple non-contiguous
61 registers. */
62 rtx reg;
63 /* Register to pass this argument in when generating tail call sequence.
64 This is not the same register as for normal calls on machines with
65 register windows. */
66 rtx tail_call_reg;
67 /* If REG was promoted from the actual mode of the argument expression,
68 indicates whether the promotion is sign- or zero-extended. */
70 /* Number of registers to use. 0 means put the whole arg in registers.
71 Also 0 if not passed in registers. */
73 /* Nonzero if argument must be passed on stack.
74 Note that some arguments may be passed on the stack
75 even though pass_on_stack is zero, just because FUNCTION_ARG says so.
76 pass_on_stack identifies arguments that *cannot* go in registers. */
78 /* Some fields packaged up for locate_and_pad_parm. */
80 /* Location on the stack at which parameter should be stored. The store
81 has already been done if STACK == VALUE. */
82 rtx stack;
83 /* Location on the stack of the start of this argument slot. This can
84 differ from STACK if this arg pads downward. This location is known
85 to be aligned to FUNCTION_ARG_BOUNDARY. */
86 rtx stack_slot;
87 /* Place that this stack area has been saved, if needed. */
88 rtx save_area;
89 /* If an argument's alignment does not permit direct copying into registers,
90 copy in smaller-sized pieces into pseudos. These are stored in a
91 block pointed to by this field. The next field says how many
92 word-sized pseudos we made. */
95 };
97 /* A vector of one char per byte of stack space. A byte if nonzero if
98 the corresponding stack location has been used.
99 This vector is used to prevent a function call within an argument from
100 clobbering any stack already set up. */
103 /* Size of STACK_USAGE_MAP. */
106 /* A bitmap of virtual-incoming stack space. Bit is set if the corresponding
107 stack location's tail call argument has been already stored into the stack.
108 This bitmap is used to prevent sibling call optimization if function tries
109 to use parent's incoming argument slots when they have been already
110 overwritten with tail call arguments. */
113 /* stack_arg_under_construction is nonzero when an argument may be
114 initialized with a constructor call (including a C function that
115 returns a BLKmode struct) and expand_call must take special action
116 to make sure the object being constructed does not overlap the
117 argument list for the constructor call. */
125 CUMULATIVE_ARGS *);
154 #ifdef REG_PARM_STACK_SPACE
157 #endif
158 \f
159 /* If WHICH is 1, return 1 if EXP contains a call to the built-in function
160 `alloca'.
162 If WHICH is 0, return 1 if EXP contains a call to any function.
163 Actually, we only need return 1 if evaluating EXP would require pushing
164 arguments on the stack, but that is too difficult to compute, so we just
165 assume any function call might require the stack. */
169 static int
171 {
178 }
180 /* Recursive function to do the work of above function. */
182 static int
184 {
190 /* If this code is language-specific, we don't know what it will do. */
195 {
201 && (TYPE_RETURNS_STACK_DEPRESSED
215 {
216 tree tem;
221 }
231 calls_function_save_exprs);
236 {
237 tree local;
238 tree subblock;
246 subblock;
250 }
261 }
263 /* Only expressions and blocks can contain calls. */
273 }
274 \f
275 /* Force FUNEXP into a form suitable for the address of a CALL,
276 and return that as an rtx. Also load the static chain register
277 if FNDECL is a nested function.
279 CALL_FUSAGE points to a variable holding the prospective
280 CALL_INSN_FUNCTION_USAGE information. */
282 rtx
285 {
291 /* Get possible static chain value for nested function in C. */
294 /* Make a valid memory address and copy constants through pseudo-regs,
295 but not for a constant address if -fno-function-cse. */
297 /* If we are using registers for parameters, force the
298 function address into a register now. */
303 {
304 #ifndef NO_FUNCTION_CSE
306 #ifdef NO_RECURSIVE_FUNCTION_CSE
308 #endif
310 #endif
311 }
314 {
319 }
322 }
324 /* Generate instructions to call function FUNEXP,
325 and optionally pop the results.
326 The CALL_INSN is the first insn generated.
328 FNDECL is the declaration node of the function. This is given to the
329 macro RETURN_POPS_ARGS to determine whether this function pops its own args.
331 FUNTYPE is the data type of the function. This is given to the macro
332 RETURN_POPS_ARGS to determine whether this function pops its own args.
333 We used to allow an identifier for library functions, but that doesn't
334 work when the return type is an aggregate type and the calling convention
335 says that the pointer to this aggregate is to be popped by the callee.
337 STACK_SIZE is the number of bytes of arguments on the stack,
338 ROUNDED_STACK_SIZE is that number rounded up to
339 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
340 both to put into the call insn and to generate explicit popping
341 code if necessary.
343 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
344 It is zero if this call doesn't want a structure value.
346 NEXT_ARG_REG is the rtx that results from executing
347 FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1)
348 just after all the args have had their registers assigned.
349 This could be whatever you like, but normally it is the first
350 arg-register beyond those used for args in this call,
351 or 0 if all the arg-registers are used in this call.
352 It is passed on to `gen_call' so you can put this info in the call insn.
354 VALREG is a hard register in which a value is returned,
355 or 0 if the call does not return a value.
357 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
358 the args to this call were processed.
359 We restore `inhibit_defer_pop' to that value.
361 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
362 denote registers used by the called function. */
364 static void
366 HOST_WIDE_INT stack_size ATTRIBUTE_UNUSED,
367 HOST_WIDE_INT rounded_stack_size,
368 HOST_WIDE_INT struct_value_size ATTRIBUTE_UNUSED,
372 {
374 rtx call_insn;
377 #if defined (HAVE_call) && defined (HAVE_call_value)
378 rtx struct_value_size_rtx;
380 #endif
382 #ifdef CALL_POPS_ARGS
384 #endif
386 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
387 and we don't want to load it into a register as an optimization,
388 because prepare_call_address already did it if it should be done. */
392 #if defined (HAVE_sibcall_pop) && defined (HAVE_sibcall_value_pop)
396 {
398 rtx pat;
400 /* If this subroutine pops its own args, record that in the call insn
401 if possible, for the sake of frame pointer elimination. */
407 n_pop);
408 else
414 }
415 else
416 #endif
418 #if defined (HAVE_call_pop) && defined (HAVE_call_value_pop)
419 /* If the target has "call" or "call_value" insns, then prefer them
420 if no arguments are actually popped. If the target does not have
421 "call" or "call_value" insns, then we must use the popping versions
422 even if the call has no arguments to pop. */
423 #if defined (HAVE_call) && defined (HAVE_call_value)
426 #else
428 #endif
429 {
431 rtx pat;
433 /* If this subroutine pops its own args, record that in the call insn
434 if possible, for the sake of frame pointer elimination. */
440 else
446 }
447 else
448 #endif
450 #if defined (HAVE_sibcall) && defined (HAVE_sibcall_value)
453 {
457 rounded_stack_size_rtx,
459 else
462 struct_value_size_rtx));
463 }
464 else
465 #endif
467 #if defined (HAVE_call) && defined (HAVE_call_value)
469 {
474 NULL_RTX));
475 else
478 struct_value_size_rtx));
479 }
480 else
481 #endif
484 /* Find the call we just emitted. */
487 /* Mark memory as used for "pure" function call. */
489 call_fusage
490 = gen_rtx_EXPR_LIST
494 call_fusage);
496 /* Put the register usage information there. */
499 /* If this is a const call, then set the insn's unchanging bit. */
503 /* If this call can't throw, attach a REG_EH_REGION reg note to that
504 effect. */
508 else
519 {
523 }
527 /* Restore this now, so that we do defer pops for this call's args
528 if the context of the call as a whole permits. */
532 {
541 }
544 {
545 /* If returning from the subroutine does not automatically pop the args,
546 we need an instruction to pop them sooner or later.
547 Perhaps do it now; perhaps just record how much space to pop later.
549 If returning from the subroutine does pop the args, indicate that the
550 stack pointer will be changed. */
553 {
555 /* Just pretend we did the pop. */
560 else
562 }
563 }
564 /* When we accumulate outgoing args, we must avoid any stack manipulations.
565 Restore the stack pointer to its original value now. Usually
566 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
567 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
568 popping variants of functions exist as well.
570 ??? We may optimize similar to defer_pop above, but it is
571 probably not worthwhile.
573 ??? It will be worthwhile to enable combine_stack_adjustments even for
574 such machines. */
577 }
579 /* Determine if the function identified by NAME and FNDECL is one with
580 special properties we wish to know about.
582 For example, if the function might return more than one time (setjmp), then
583 set RETURNS_TWICE to a nonzero value.
585 Similarly set LONGJMP for if the function is in the longjmp family.
587 Set MAY_BE_ALLOCA for any memory allocation function that might allocate
588 space from the stack such as alloca. */
590 static int
592 {
596 /* Exclude functions not at the file scope, or not `extern',
597 since they are not the magic functions we would otherwise
598 think they are.
599 FIXME: this should be handled with attributes, not with this
600 hacky imitation of DECL_ASSEMBLER_NAME. It's (also) wrong
601 because you can declare fork() inside a function if you
602 wish. */
606 {
610 /* We assume that alloca will always be called by name. It
611 makes no sense to pass it as a pointer-to-function to
612 anything that does not understand its behavior. */
621 /* Disregard prefix _, __ or __x. */
623 {
628 else
630 }
633 {
646 }
659 /* Linux specific: __clone. check NAME to insist on the
660 leading underscores, to avoid polluting the ISO / POSIX
661 namespace. */
670 }
672 }
674 /* Return nonzero when tree represent call to longjmp. */
676 int
678 {
680 }
682 /* Return true when exp contains alloca call. */
683 bool
685 {
694 }
696 /* Detect flags (function attributes) from the function decl or type node. */
698 int
700 {
705 {
710 {
715 }
717 /* The function exp may have the `malloc' attribute. */
721 /* The function exp may have the `pure' attribute. */
730 }
738 /* Mark if the function returns with the stack pointer depressed. We
739 cannot consider it pure or constant in that case. */
741 {
744 }
747 }
749 /* Detect flags from a CALL_EXPR. */
751 int
753 {
759 else
760 {
764 else
766 }
769 }
771 /* Precompute all register parameters as described by ARGS, storing values
772 into fields within the ARGS array.
774 NUM_ACTUALS indicates the total number elements in the ARGS array.
776 Set REG_PARM_SEEN if we encounter a register parameter. */
778 static void
780 {
787 {
791 {
798 /* ANSI doesn't require a sequence point here,
799 but PCC has one, so this will avoid some problems. */
801 }
803 /* If the value is a non-legitimate constant, force it into a
804 pseudo now. TLS symbols sometimes need a call to resolve. */
809 /* If we are to promote the function arg to a wider mode,
810 do it now. */
818 /* If the value is expensive, and we are inside an appropriately
819 short loop, put the value into a pseudo and then put the pseudo
820 into the hard reg.
822 For small register classes, also do this if this call uses
823 register parameters. This is to avoid reload conflicts while
824 loading the parameters registers. */
834 }
835 }
837 #ifdef REG_PARM_STACK_SPACE
839 /* The argument list is the property of the called routine and it
840 may clobber it. If the fixed area has been used for previous
841 parameters, we must save and restore it. */
843 static rtx
844 save_fixed_argument_area (int reg_parm_stack_space, rtx argblock, int *low_to_save, int *high_to_save)
845 {
849 /* Compute the boundary of the area that needs to be saved, if any. */
851 #ifdef ARGS_GROW_DOWNWARD
853 #endif
859 {
863 rtx stack_area;
864 rtx save_area;
867 ;
875 /* If we don't have the required alignment, must do this
876 in BLKmode. */
881 #ifdef ARGS_GROW_DOWNWARD
883 #else
885 #endif
889 delta)));
893 {
897 }
898 else
899 {
902 }
905 }
908 }
910 static void
912 {
915 rtx stack_area;
917 #ifdef ARGS_GROW_DOWNWARD
919 #else
921 #endif
929 else
932 BLOCK_OP_CALL_PARM);
933 }
936 /* If any elements in ARGS refer to parameters that are to be passed in
937 registers, but not in memory, and whose alignment does not permit a
938 direct copy into registers. Copy the values into a group of pseudos
939 which we will later copy into the appropriate hard registers.
941 Pseudos for each unaligned argument will be stored into the array
942 args[argnum].aligned_regs. The caller is responsible for deallocating
943 the aligned_regs array if it is nonzero. */
945 static void
947 {
955 {
963 /* Structures smaller than a word are normally aligned to the
964 least significant byte. On a BYTES_BIG_ENDIAN machine,
965 this means we must skip the empty high order bytes when
966 calculating the bit offset. */
968 #ifdef BLOCK_REG_PADDING
972 #else
973 && BYTES_BIG_ENDIAN
974 #endif
975 )
979 {
988 /* There is no need to restrict this code to loading items
989 in TYPE_ALIGN sized hunks. The bitfield instructions can
990 load up entire word sized registers efficiently.
992 ??? This may not be needed anymore.
993 We use to emit a clobber here but that doesn't let later
994 passes optimize the instructions we emit. By storing 0 into
995 the register later passes know the first AND to zero out the
996 bitfield being set in the register is unnecessary. The store
997 of 0 will be deleted as will at least the first AND. */
1004 }
1005 }
1006 }
1008 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
1009 ACTPARMS.
1011 NUM_ACTUALS is the total number of parameters.
1013 N_NAMED_ARGS is the total number of named arguments.
1015 FNDECL is the tree code for the target of this call (if known)
1017 ARGS_SO_FAR holds state needed by the target to know where to place
1018 the next argument.
1020 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
1021 for arguments which are passed in registers.
1023 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
1024 and may be modified by this routine.
1026 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
1027 flags which may may be modified by this routine.
1029 CALL_FROM_THUNK_P is true if this call is the jump from a thunk to
1030 the thunked-to function. */
1032 static void
1043 {
1044 /* 1 if scanning parms front to back, -1 if scanning back to front. */
1047 /* Count arg position in order args appear. */
1051 tree p;
1056 /* In this loop, we consider args in the order they are written.
1057 We fill up ARGS from the front or from the back if necessary
1058 so that in any case the first arg to be pushed ends up at the front. */
1061 {
1063 /* In this case, must reverse order of args
1064 so that we compute and push the last arg first. */
1065 }
1066 else
1067 {
1069 }
1071 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1073 {
1080 /* Replace erroneous argument with constant zero. */
1084 /* If TYPE is a transparent union, pass things the way we would
1085 pass the first field of the union. We have already verified that
1086 the modes are the same. */
1090 /* Decide where to pass this arg.
1092 args[i].reg is nonzero if all or part is passed in registers.
1094 args[i].partial is nonzero if part but not all is passed in registers,
1095 and the exact value says how many words are passed in registers.
1097 args[i].pass_on_stack is nonzero if the argument must at least be
1098 computed on the stack. It may then be loaded back into registers
1099 if args[i].reg is nonzero.
1101 These decisions are driven by the FUNCTION_... macros and must agree
1102 with those made by function.c. */
1104 /* See if this argument should be passed by invisible reference. */
1107 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
1110 #endif
1111 )
1112 {
1113 /* If we're compiling a thunk, pass through invisible
1114 references instead of making a copy. */
1116 #ifdef FUNCTION_ARG_CALLEE_COPIES
1119 /* If it's in a register, we must make a copy of it too. */
1120 /* ??? Is this a sufficient test? Is there a better one? */
1124 #endif
1125 )
1126 {
1127 /* C++ uses a TARGET_EXPR to indicate that we want to make a
1128 new object from the argument. If we are passing by
1129 invisible reference, the callee will do that for us, so we
1130 can strip off the TARGET_EXPR. This is not always safe,
1131 but it is safe in the only case where this is a useful
1132 optimization; namely, when the argument is a plain object.
1133 In that case, the frontend is just asking the backend to
1134 make a bitwise copy of the argument. */
1145 }
1147 {
1148 /* In the V3 C++ ABI, parameters are destroyed in the caller.
1149 We implement this by passing the address of the temporary
1150 rather than expanding it into another allocated slot. */
1155 }
1156 else
1157 {
1158 /* We make a copy of the object and pass the address to the
1159 function being called. */
1160 rtx copy;
1166 STACK_CHECK_MAX_VAR_SIZE))))
1167 {
1168 /* This is a variable-sized object. Make space on the stack
1169 for it. */
1173 {
1177 }
1180 allocate_dynamic_stack_space
1183 }
1184 else
1194 }
1195 }
1208 #ifdef FUNCTION_INCOMING_ARG
1209 /* If this is a sibling call and the machine has register windows, the
1210 register window has to be unwinded before calling the routine, so
1211 arguments have to go into the incoming registers. */
1214 #else
1216 #endif
1218 #ifdef FUNCTION_ARG_PARTIAL_NREGS
1223 #endif
1227 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1228 it means that we are to pass this arg in the register(s) designated
1229 by the PARALLEL, but also to pass it in the stack. */
1234 /* If this is an addressable type, we must preallocate the stack
1235 since we must evaluate the object into its final location.
1237 If this is to be passed in both registers and the stack, it is simpler
1238 to preallocate. */
1243 /* If this is an addressable type, we cannot pre-evaluate it. Thus,
1244 we cannot consider this function call constant. */
1248 /* Compute the stack-size of this argument. */
1253 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1255 #else
1257 #endif
1260 #ifdef BLOCK_REG_PADDING
1261 else
1262 /* The argument is passed entirely in registers. See at which
1263 end it should be padded. */
1267 #endif
1269 /* Update ARGS_SIZE, the total stack space for args so far. */
1275 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1276 have been used, etc. */
1280 }
1281 }
1283 /* Update ARGS_SIZE to contain the total size for the argument block.
1284 Return the original constant component of the argument block's size.
1286 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1287 for arguments passed in registers. */
1289 static int
1293 {
1296 /* For accumulate outgoing args mode we don't need to align, since the frame
1297 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1298 backends from generating misaligned frame sizes. */
1302 /* Compute the actual size of the argument block required. The variable
1303 and constant sizes must be combined, the size may have to be rounded,
1304 and there may be a minimum required size. */
1307 {
1313 {
1314 /* We don't handle this case yet. To handle it correctly we have
1315 to add the delta, round and subtract the delta.
1316 Currently no machine description requires this support. */
1320 }
1323 {
1324 args_size->var
1328 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1329 /* The area corresponding to register parameters is not to count in
1330 the size of the block we need. So make the adjustment. */
1331 args_size->var
1334 #endif
1335 }
1336 }
1337 else
1338 {
1343 + stack_pointer_delta
1345 / preferred_stack_boundary
1350 reg_parm_stack_space);
1352 #ifdef MAYBE_REG_PARM_STACK_SPACE
1355 #endif
1357 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1359 #endif
1360 }
1362 }
1364 /* Precompute parameters as needed for a function call.
1366 FLAGS is mask of ECF_* constants.
1368 NUM_ACTUALS is the number of arguments.
1370 ARGS is an array containing information for each argument; this
1371 routine fills in the INITIAL_VALUE and VALUE fields for each
1372 precomputed argument. */
1374 static void
1376 {
1379 /* If this function call is cse'able, precompute all the parameters.
1380 Note that if the parameter is constructed into a temporary, this will
1381 cause an additional copy because the parameter will be constructed
1382 into a temporary location and then copied into the outgoing arguments.
1383 If a parameter contains a call to alloca and this function uses the
1384 stack, precompute the parameter. */
1386 /* If we preallocated the stack space, and some arguments must be passed
1387 on the stack, then we must precompute any parameter which contains a
1388 function call which will store arguments on the stack.
1389 Otherwise, evaluating the parameter may clobber previous parameters
1390 which have already been stored into the stack. (we have code to avoid
1391 such case by saving the outgoing stack arguments, but it results in
1392 worse code) */
1397 {
1400 /* If this is an addressable type, we cannot pre-evaluate it. */
1407 /* ANSI doesn't require a sequence point here,
1408 but PCC has one, so this will avoid some problems. */
1416 {
1420 #ifdef PROMOTE_FOR_CALL_ONLY
1421 /* CSE will replace this only if it contains args[i].value
1422 pseudo, so convert it down to the declared mode using
1423 a SUBREG. */
1426 {
1432 }
1433 #endif
1434 }
1435 }
1436 }
1438 /* Given the current state of MUST_PREALLOCATE and information about
1439 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1440 compute and return the final value for MUST_PREALLOCATE. */
1442 static int
1443 finalize_must_preallocate (int must_preallocate, int num_actuals, struct arg_data *args, struct args_size *args_size)
1444 {
1445 /* See if we have or want to preallocate stack space.
1447 If we would have to push a partially-in-regs parm
1448 before other stack parms, preallocate stack space instead.
1450 If the size of some parm is not a multiple of the required stack
1451 alignment, we must preallocate.
1453 If the total size of arguments that would otherwise create a copy in
1454 a temporary (such as a CALL) is more than half the total argument list
1455 size, preallocation is faster.
1457 Another reason to preallocate is if we have a machine (like the m88k)
1458 where stack alignment is required to be maintained between every
1459 pair of insns, not just when the call is made. However, we assume here
1460 that such machines either do not have push insns (and hence preallocation
1461 would occur anyway) or the problem is taken care of with
1462 PUSH_ROUNDING. */
1465 {
1471 {
1482 copy_to_evaluate_size
1484 }
1489 }
1491 }
1493 /* If we preallocated stack space, compute the address of each argument
1494 and store it into the ARGS array.
1496 We need not ensure it is a valid memory address here; it will be
1497 validized when it is used.
1499 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1501 static void
1503 {
1505 {
1513 {
1516 rtx addr;
1518 /* Skip this parm if it will not be passed on the stack. */
1524 else
1535 else
1544 /* Function incoming arguments may overlap with sibling call
1545 outgoing arguments and we cannot allow reordering of reads
1546 from function arguments with stores to outgoing arguments
1547 of sibling calls. */
1550 }
1551 }
1552 }
1554 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1555 in a call instruction.
1557 FNDECL is the tree node for the target function. For an indirect call
1558 FNDECL will be NULL_TREE.
1560 ADDR is the operand 0 of CALL_EXPR for this call. */
1562 static rtx
1564 {
1565 rtx funexp;
1567 /* Get the function to call, in the form of RTL. */
1569 {
1570 /* If this is the first use of the function, see if we need to
1571 make an external definition for it. */
1573 {
1576 }
1578 /* Get a SYMBOL_REF rtx for the function address. */
1580 }
1581 else
1582 /* Generate an rtx (probably a pseudo-register) for the address. */
1583 {
1588 }
1590 }
1592 /* Do the register loads required for any wholly-register parms or any
1593 parms which are passed both on the stack and in a register. Their
1594 expressions were already evaluated.
1596 Mark all register-parms as living through the call, putting these USE
1597 insns in the CALL_INSN_FUNCTION_USAGE field.
1599 When IS_SIBCALL, perform the check_sibcall_overlap_argument_overlap
1600 checking, setting *SIBCALL_FAILURE if appropriate. */
1602 static void
1606 {
1610 {
1614 {
1619 /* Set to non-negative if must move a word at a time, even if just
1620 one word (e.g, partial == 1 && mode == DFmode). Set to -1 if
1621 we just use a normal move insn. This value can be zero if the
1622 argument is a zero size structure with no fields. */
1627 {
1630 }
1631 else
1634 /* Handle calls that pass values in multiple non-contiguous
1635 locations. The Irix 6 ABI has examples of this. */
1638 {
1642 }
1644 /* If simple case, just do move. If normal partial, store_one_arg
1645 has already loaded the register for us. In all other cases,
1646 load the register(s) from memory. */
1649 {
1651 #ifdef BLOCK_REG_PADDING
1652 /* Handle case where we have a value that needs shifting
1653 up to the msb. eg. a QImode value and we're padding
1654 upward on a BYTES_BIG_ENDIAN machine. */
1658 {
1659 rtx x;
1662 /* Assigning REG here rather than a temp makes CALL_FUSAGE
1663 report the whole reg as used. Strictly speaking, the
1664 call only uses SIZE bytes at the msb end, but it doesn't
1665 seem worth generating rtl to say that. */
1671 }
1672 #endif
1673 }
1675 /* If we have pre-computed the values to put in the registers in
1676 the case of non-aligned structures, copy them in now. */
1684 {
1687 #ifdef BLOCK_REG_PADDING
1688 /* Handle a BLKmode that needs shifting. */
1691 {
1703 }
1704 else
1705 #endif
1707 }
1709 /* When a parameter is a block, and perhaps in other cases, it is
1710 possible that it did a load from an argument slot that was
1711 already clobbered. */
1716 /* Handle calls that pass values in multiple non-contiguous
1717 locations. The Irix 6 ABI has examples of this. */
1724 }
1725 }
1726 }
1728 /* Try to integrate function. See expand_inline_function for documentation
1729 about the parameters. */
1731 static rtx
1734 {
1735 rtx temp;
1736 rtx before_call;
1741 #ifdef REG_PARM_STACK_SPACE
1742 #ifdef MAYBE_REG_PARM_STACK_SPACE
1744 #else
1746 #endif
1747 #endif
1755 structure_value_addr);
1759 /* If inlining succeeded, return. */
1761 {
1763 {
1764 /* If the outgoing argument list must be preserved, push
1765 the stack before executing the inlined function if it
1766 makes any calls. */
1772 ;
1775 {
1776 rtx first_insn
1780 /* Look for a call in the inline function code.
1781 If DECL_SAVED_INSNS (fndecl)->outgoing_args_size is
1782 nonzero then there is a call and it is not necessary
1783 to scan the insns. */
1791 {
1792 /* Reserve enough stack space so that the largest
1793 argument list of any function call in the inline
1794 function does not overlap the argument list being
1795 evaluated. This is usually an overestimate because
1796 allocate_dynamic_stack_space reserves space for an
1797 outgoing argument list in addition to the requested
1798 space, but there is no way to ask for stack space such
1799 that an argument list of a certain length can be
1800 safely constructed.
1802 Add the stack space reserved for register arguments, if
1803 any, in the inline function. What is really needed is the
1804 largest value of reg_parm_stack_space in the inline
1805 function, but that is not available. Using the current
1806 value of reg_parm_stack_space is wrong, but gives
1807 correct results on all supported machines. */
1820 }
1821 }
1822 }
1824 /* If the result is equivalent to TARGET, return TARGET to simplify
1825 checks in store_expr. They can be equivalent but not equal in the
1826 case of a function that returns BLKmode. */
1830 }
1832 /* If inlining failed, mark FNDECL as needing to be compiled
1833 separately after all. If function was declared inline,
1834 give a warning. */
1837 {
1840 }
1843 }
1845 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
1846 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
1847 bytes, then we would need to push some additional bytes to pad the
1848 arguments. So, we compute an adjust to the stack pointer for an
1849 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
1850 bytes. Then, when the arguments are pushed the stack will be perfectly
1851 aligned. ARGS_SIZE->CONSTANT is set to the number of bytes that should
1852 be popped after the call. Returns the adjustment. */
1854 static int
1858 {
1859 /* The number of bytes to pop so that the stack will be
1860 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
1861 HOST_WIDE_INT adjustment;
1862 /* The alignment of the stack after the arguments are pushed, if we
1863 just pushed the arguments without adjust the stack here. */
1864 HOST_WIDE_INT unadjusted_alignment;
1866 unadjusted_alignment
1870 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
1871 as possible -- leaving just enough left to cancel out the
1872 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
1873 PENDING_STACK_ADJUST is non-negative, and congruent to
1874 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
1876 /* Begin by trying to pop all the bytes. */
1877 unadjusted_alignment
1878 = (unadjusted_alignment
1881 /* Push enough additional bytes that the stack will be aligned
1882 after the arguments are pushed. */
1884 {
1887 else
1889 }
1891 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
1892 bytes after the call. The right number is the entire
1893 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
1894 by the arguments in the first place. */
1895 args_size->constant
1899 }
1901 /* Scan X expression if it does not dereference any argument slots
1902 we already clobbered by tail call arguments (as noted in stored_args_map
1903 bitmap).
1904 Return nonzero if X expression dereferences such argument slots,
1905 zero otherwise. */
1907 static int
1909 {
1910 RTX_CODE code;
1921 {
1926 current_function_internal_arg_pointer
1929 else
1932 #ifdef ARGS_GROW_DOWNWARD
1934 #endif
1942 }
1944 /* Scan all subexpressions. */
1947 {
1949 {
1952 }
1954 {
1958 }
1959 }
1961 }
1963 /* Scan sequence after INSN if it does not dereference any argument slots
1964 we already clobbered by tail call arguments (as noted in stored_args_map
1965 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
1966 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
1967 should be 0). Return nonzero if sequence after INSN dereferences such argument
1968 slots, zero otherwise. */
1970 static int
1972 {
1977 else
1986 {
1987 #ifdef ARGS_GROW_DOWNWARD
1989 #else
1991 #endif
1995 }
1997 }
1999 static tree
2001 {
2003 {
2012 {
2018 }
2023 }
2025 }
2028 /* If function value *VALUE was returned at the most significant end of a
2029 register, shift it towards the least significant end and convert it to
2030 TYPE's mode. Return true and update *VALUE if some action was needed.
2032 TYPE is the type of the function's return value, which is known not
2033 to have mode BLKmode. */
2035 static bool
2037 {
2039 {
2040 HOST_WIDE_INT shift;
2045 {
2050 }
2051 }
2053 }
2055 /* Generate all the code for a function call
2056 and return an rtx for its value.
2057 Store the value in TARGET (specified as an rtx) if convenient.
2058 If the value is stored in TARGET then TARGET is returned.
2059 If IGNORE is nonzero, then we ignore the value of the function call. */
2061 rtx
2063 {
2064 /* Nonzero if we are currently expanding a call. */
2067 /* List of actual parameters. */
2069 /* RTX for the function to be called. */
2070 rtx funexp;
2071 /* Sequence of insns to perform a tail recursive "call". */
2073 /* Sequence of insns to perform a normal "call". */
2075 /* Sequence of insns to perform a tail recursive "call". */
2077 /* Data type of the function. */
2078 tree funtype;
2079 tree type_arg_types;
2080 /* Declaration of the function being called,
2081 or 0 if the function is computed (not known by name). */
2083 /* The type of the function being called. */
2084 tree fntype;
2085 rtx insn;
2090 /* Register in which non-BLKmode value will be returned,
2091 or 0 if no value or if value is BLKmode. */
2092 rtx valreg;
2093 /* Address where we should return a BLKmode value;
2094 0 if value not BLKmode. */
2096 /* Nonzero if that address is being passed by treating it as
2097 an extra, implicit first parameter. Otherwise,
2098 it is passed by being copied directly into struct_value_rtx. */
2100 /* Size of aggregate value wanted, or zero if none wanted
2101 or if we are using the non-reentrant PCC calling convention
2102 or expecting the value in registers. */
2104 /* Nonzero if called function returns an aggregate in memory PCC style,
2105 by returning the address of where to find it. */
2109 /* Number of actual parameters in this call, including struct value addr. */
2111 /* Number of named args. Args after this are anonymous ones
2112 and they must all go on the stack. */
2115 /* Vector of information about each argument.
2116 Arguments are numbered in the order they will be pushed,
2117 not the order they are written. */
2120 /* Total size in bytes of all the stack-parms scanned so far. */
2123 /* Size of arguments before any adjustments (such as rounding). */
2125 /* Data on reg parms scanned so far. */
2126 CUMULATIVE_ARGS args_so_far;
2127 /* Nonzero if a reg parm has been scanned. */
2129 /* Nonzero if this is an indirect function call. */
2131 /* Nonzero if we must avoid push-insns in the args for this call.
2132 If stack space is allocated for register parameters, but not by the
2133 caller, then it is preallocated in the fixed part of the stack frame.
2134 So the entire argument block must then be preallocated (i.e., we
2135 ignore PUSH_ROUNDING in that case). */
2139 /* Size of the stack reserved for parameter registers. */
2142 /* Address of space preallocated for stack parms
2143 (on machines that lack push insns), or 0 if space not preallocated. */
2146 /* Mask of ECF_ flags. */
2148 /* Nonzero if this is a call to an inline function. */
2150 #ifdef REG_PARM_STACK_SPACE
2151 /* Define the boundary of the register parm stack space that needs to be
2152 saved, if any. */
2155 #endif
2163 /* State variables to track stack modifications. */
2169 /* Some stack pointer alterations we make are performed via
2170 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2171 which we then also need to save/restore along the way. */
2174 rtx call_fusage;
2178 /* The alignment of the stack, in bits. */
2179 HOST_WIDE_INT preferred_stack_boundary;
2180 /* The alignment of the stack, in bytes. */
2181 HOST_WIDE_INT preferred_unit_stack_boundary;
2183 /* See if this is "nothrow" function call. */
2187 /* See if we can find a DECL-node for the actual function.
2188 As a result, decide whether this is a call to an integrable function. */
2192 {
2201 {
2202 /* In case this function later becomes inlinable,
2203 record that there was already a non-inline call to it.
2205 Use abstraction instead of setting TREE_ADDRESSABLE
2206 directly. */
2209 {
2212 }
2214 }
2223 }
2225 /* If we don't have specific function to call, see if we have a
2226 attributes set in the type. */
2227 else
2228 {
2235 }
2239 /* Warn if this value is an aggregate type,
2240 regardless of which calling convention we are using for it. */
2244 /* If the result of a pure or const function call is ignored (or void),
2245 and none of its arguments are volatile, we can avoid expanding the
2246 call and just evaluate the arguments for side-effects. */
2250 {
2252 tree arg;
2256 {
2259 }
2262 {
2267 }
2268 }
2270 #ifdef REG_PARM_STACK_SPACE
2271 #ifdef MAYBE_REG_PARM_STACK_SPACE
2273 #else
2275 #endif
2276 #endif
2278 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2281 #endif
2283 /* Set up a place to return a structure. */
2285 /* Cater to broken compilers. */
2287 {
2288 /* This call returns a big structure. */
2291 #ifdef PCC_STATIC_STRUCT_RETURN
2292 {
2294 /* Easier than making that case work right. */
2296 {
2297 /* In case this is a static function, note that it has been
2298 used. */
2302 }
2303 }
2305 {
2309 {
2310 /* The structure value address arg is already in actparms.
2311 Pull it out. It might be nice to just leave it there, but
2312 we need to set structure_value_addr. */
2317 }
2320 else
2321 {
2322 /* For variable-sized objects, we must be called with a target
2323 specified. If we were to allocate space on the stack here,
2324 we would have no way of knowing when to free it. */
2330 }
2331 }
2333 }
2335 /* If called function is inline, try to integrate it. */
2338 {
2341 structure_value_addr);
2344 }
2346 /* Figure out the amount to which the stack should be aligned. */
2349 {
2353 }
2355 /* Operand 0 is a pointer-to-function; get the type of the function. */
2361 /* Munge the tree to split complex arguments into their imaginary
2362 and real parts. */
2364 {
2367 }
2368 else
2371 /* See if this is a call to a function that can return more than once
2372 or a call to longjmp or malloc. */
2378 /* If struct_value_rtx is 0, it means pass the address
2379 as if it were an extra parameter. */
2381 {
2382 /* If structure_value_addr is a REG other than
2383 virtual_outgoing_args_rtx, we can use always use it. If it
2384 is not a REG, we must always copy it into a register.
2385 If it is virtual_outgoing_args_rtx, we must copy it to another
2386 register in some cases. */
2388 || (ACCUMULATE_OUTGOING_ARGS
2389 && stack_arg_under_construction
2395 actparms
2398 temp),
2399 actparms);
2401 }
2403 /* Count the arguments and set NUM_ACTUALS. */
2405 num_actuals++;
2407 /* Compute number of named args.
2408 First, do a raw count of the args for INIT_CUMULATIVE_ARGS. */
2411 n_named_args
2413 /* Count the struct value address, if it is passed as a parm. */
2415 else
2416 /* If we know nothing, treat all args as named. */
2419 /* Start updating where the next arg would go.
2421 On some machines (such as the PA) indirect calls have a different
2422 calling convention than normal calls. The fourth argument in
2423 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2424 or not. */
2427 /* Now possibly adjust the number of named args.
2428 Normally, don't include the last named arg if anonymous args follow.
2429 We do include the last named arg if
2430 targetm.calls.strict_argument_naming() returns nonzero.
2431 (If no anonymous args follow, the result of list_length is actually
2432 one too large. This is harmless.)
2434 If targetm.calls.pretend_outgoing_varargs_named() returns
2435 nonzero, and targetm.calls.strict_argument_naming() returns zero,
2436 this machine will be able to place unnamed args that were passed
2437 in registers into the stack. So treat all args as named. This
2438 allows the insns emitting for a specific argument list to be
2439 independent of the function declaration.
2441 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
2442 we do not have any reliable way to pass unnamed args in
2443 registers, so we must force them into memory. */
2447 ;
2450 /* Don't include the last named arg. */
2452 else
2453 /* Treat all args as named. */
2456 /* Make a vector to hold all the information about each arg. */
2460 /* Build up entries in the ARGS array, compute the size of the
2461 arguments into ARGS_SIZE, etc. */
2470 {
2471 /* If this function requires a variable-sized argument list, don't
2472 try to make a cse'able block for this call. We may be able to
2473 do this eventually, but it is too complicated to keep track of
2474 what insns go in the cse'able block and which don't. */
2478 }
2480 /* Now make final decision about preallocating stack space. */
2485 /* If the structure value address will reference the stack pointer, we
2486 must stabilize it. We don't need to do this if we know that we are
2487 not going to adjust the stack pointer in processing this call. */
2492 structure_value_addr))
2497 /* Tail calls can make things harder to debug, and we're traditionally
2498 pushed these optimizations into -O2. Don't try if we're already
2499 expanding a call, as that means we're an argument. Don't try if
2500 there's cleanups, as we know there's code to follow the call.
2502 If rtx_equal_function_value_matters is false, that means we've
2503 finished with regular parsing. Which means that some of the
2504 machinery we use to generate tail-calls is no longer in place.
2505 This is most often true of sjlj-exceptions, which we couldn't
2506 tail-call to anyway.
2508 If current_nesting_level () == 0, we're being called after
2509 the function body has been expanded. This can happen when
2510 setting up trampolines in expand_function_end. */
2512 || !flag_optimize_sibling_calls
2513 || !rtx_equal_function_value_matters
2519 /* Tail recursion fails, when we are not dealing with recursive calls. */
2525 /* Rest of purposes for tail call optimizations to fail. */
2527 #ifdef HAVE_sibcall_epilogue
2528 !HAVE_sibcall_epilogue
2529 #else
2530 1
2531 #endif
2532 || !try_tail_call
2533 /* Doing sibling call optimization needs some work, since
2534 structure_value_addr can be allocated on the stack.
2535 It does not seem worth the effort since few optimizable
2536 sibling calls will return a structure. */
2538 /* Check whether the target is able to optimize the call
2539 into a sibcall. */
2541 /* Functions that do not return exactly once may not be sibcall
2542 optimized. */
2545 /* If the called function is nested in the current one, it might access
2546 some of the caller's arguments, but could clobber them beforehand if
2547 the argument areas are shared. */
2549 /* If this function requires more stack slots than the current
2550 function, we cannot change it into a sibling call. */
2552 /* If the callee pops its own arguments, then it must pop exactly
2553 the same number of arguments as the current function. */
2557 current_function_args_size))
2562 {
2565 /* Ok, we're going to give the tail call the old college try.
2566 This means we're going to evaluate the function arguments
2567 up to three times. There are two degrees of badness we can
2568 encounter, those that can be unsaved and those that can't.
2569 (See unsafe_for_reeval commentary for details.)
2571 Generate a new argument list. Pass safe arguments through
2572 unchanged. For the easy badness wrap them in UNSAVE_EXPRs.
2573 For hard badness, evaluate them now and put their resulting
2574 rtx in a temporary VAR_DECL.
2576 initialize_argument_information has ordered the array for the
2577 order to be pushed, and we must remember this when reconstructing
2578 the original argument order. */
2581 {
2585 }
2586 else
2587 {
2591 }
2594 {
2596 /* We need to build actparms for optimize_tail_recursion. We can
2597 safely trash away TREE_PURPOSE, since it is unused by this
2598 function. */
2601 }
2602 /* Do the same for the function address if it is an expression. */
2605 /* Expanding one of those dangerous arguments could have added
2606 cleanups, but otherwise give it a whirl. */
2609 }
2611 /* Generate a tail recursion sequence when calling ourselves. */
2614 {
2615 /* We want to emit any pending stack adjustments before the tail
2616 recursion "call". That way we know any adjustment after the tail
2617 recursion call can be ignored if we indeed use the tail recursion
2618 call expansion. */
2622 /* Emit any queued insns now; otherwise they would end up in
2623 only one of the alternates. */
2626 /* Use a new sequence to hold any RTL we generate. We do not even
2627 know if we will use this RTL yet. The final decision can not be
2628 made until after RTL generation for the entire function is
2629 complete. */
2631 /* If expanding any of the arguments creates cleanups, we can't
2632 do a tailcall. So, we'll need to pop the pending cleanups
2633 list. If, however, all goes well, and there are no cleanups
2634 then the call to expand_start_target_temps will have no
2635 effect. */
2638 {
2641 else
2643 }
2647 /* Restore the original pending stack adjustment for the sibling and
2648 normal call cases below. */
2651 }
2654 {
2655 /* A fork duplicates the profile information, and an exec discards
2656 it. We can't rely on fork/exec to be paired. So write out the
2657 profile information we have gathered so far, and clear it. */
2658 /* ??? When Linux's __clone is called with CLONE_VM set, profiling
2659 is subject to race conditions, just as with multithreaded
2660 programs. */
2663 }
2665 /* Ensure current function's preferred stack boundary is at least
2666 what we need. We don't have to increase alignment for recursive
2667 functions. */
2676 function_call_count++;
2678 /* We want to make two insn chains; one for a sibling call, the other
2679 for a normal call. We will select one of the two chains after
2680 initial RTL generation is complete. */
2682 {
2684 /* We want to emit any pending stack adjustments before the tail
2685 recursion "call". That way we know any adjustment after the tail
2686 recursion call can be ignored if we indeed use the tail recursion
2687 call expansion. */
2690 rtx insns;
2694 {
2695 /* Emit any queued insns now; otherwise they would end up in
2696 only one of the alternates. */
2699 /* State variables we need to save and restore between
2700 iterations. */
2703 }
2706 else
2709 /* Other state variables that we must reinitialize each time
2710 through the loop (that are not initialized by the loop itself). */
2714 /* Start a new sequence for the normal call case.
2716 From this point on, if the sibling call fails, we want to set
2717 sibcall_failure instead of continuing the loop. */
2721 {
2722 /* We know at this point that there are not currently any
2723 pending cleanups. If, however, in the process of evaluating
2724 the arguments we were to create some, we'll need to be
2725 able to get rid of them. */
2727 }
2729 /* Don't let pending stack adjusts add up to too much.
2730 Also, do all pending adjustments now if there is any chance
2731 this might be a call to alloca or if we are expanding a sibling
2732 call sequence or if we are calling a function that is to return
2733 with stack pointer depressed.
2734 Also do the adjustments before a throwing call, otherwise
2735 exception handling can fail; PR 19225. */
2744 /* When calling a const function, we must pop the stack args right away,
2745 so that the pop is deleted or moved with the call. */
2747 NO_DEFER_POP;
2749 #ifdef FINAL_REG_PARM_STACK_SPACE
2752 #endif
2753 /* Precompute any arguments as needed. */
2757 /* Now we are about to start emitting insns that can be deleted
2758 if a libcall is deleted. */
2763 /* Compute the actual size of the argument block required. The variable
2764 and constant sizes must be combined, the size may have to be rounded,
2765 and there may be a minimum required size. When generating a sibcall
2766 pattern, do not round up, since we'll be re-using whatever space our
2767 caller provided. */
2768 unadjusted_args_size
2776 /* The argument block when performing a sibling call is the
2777 incoming argument block. */
2779 {
2781 argblock
2782 #ifdef STACK_GROWS_DOWNWARD
2784 #else
2786 #endif
2789 }
2791 /* If we have no actual push instructions, or shouldn't use them,
2792 make space for all args right now. */
2794 {
2796 {
2801 /* stack_arg_under_construction says whether a stack arg is
2802 being constructed at the old stack level. Pushing the stack
2803 gets a clean outgoing argument block. */
2806 }
2808 }
2809 else
2810 {
2811 /* Note that we must go through the motions of allocating an argument
2812 block even if the size is zero because we may be storing args
2813 in the area reserved for register arguments, which may be part of
2814 the stack frame. */
2818 /* Store the maximum argument space used. It will be pushed by
2819 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2820 checking). */
2826 {
2828 {
2829 /* Since the stack pointer will never be pushed, it is
2830 possible for the evaluation of a parm to clobber
2831 something we have already written to the stack.
2832 Since most function calls on RISC machines do not use
2833 the stack, this is uncommon, but must work correctly.
2835 Therefore, we save any area of the stack that was already
2836 written and that we are using. Here we set up to do this
2837 by making a new stack usage map from the old one. The
2838 actual save will be done by store_one_arg.
2840 Another approach might be to try to reorder the argument
2841 evaluations to avoid this conflicting stack usage. */
2843 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2844 /* Since we will be writing into the entire argument area,
2845 the map must be allocated for its entire size, not just
2846 the part that is the responsibility of the caller. */
2848 #endif
2850 #ifdef ARGS_GROW_DOWNWARD
2853 #else
2855 needed);
2856 #endif
2861 initial_highest_arg_in_use);
2865 (highest_outgoing_arg_in_use
2869 /* The address of the outgoing argument list must not be
2870 copied to a register here, because argblock would be left
2871 pointing to the wrong place after the call to
2872 allocate_dynamic_stack_space below. */
2875 }
2876 else
2877 {
2879 {
2880 /* Try to reuse some or all of the pending_stack_adjust
2881 to get this space. */
2882 needed
2883 = (combine_pending_stack_adjustment_and_call
2886 preferred_unit_stack_boundary));
2888 /* combine_pending_stack_adjustment_and_call computes
2889 an adjustment before the arguments are allocated.
2890 Account for them and see whether or not the stack
2891 needs to go up or down. */
2895 {
2896 /* We're releasing stack space. */
2897 /* ??? We can avoid any adjustment at all if we're
2898 already aligned. FIXME. */
2902 }
2903 else
2904 /* We need to allocate space. We'll do that in
2905 push_block below. */
2907 }
2909 /* Special case this because overhead of `push_block' in
2910 this case is non-trivial. */
2913 else
2914 {
2916 #ifdef ARGS_GROW_DOWNWARD
2918 #endif
2919 }
2921 /* We only really need to call `copy_to_reg' in the case
2922 where push insns are going to be used to pass ARGBLOCK
2923 to a function call in ARGS. In that case, the stack
2924 pointer changes value from the allocation point to the
2925 call point, and hence the value of
2926 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2927 as well always do it. */
2929 }
2930 }
2931 }
2934 {
2935 /* The save/restore code in store_one_arg handles all
2936 cases except one: a constructor call (including a C
2937 function returning a BLKmode struct) to initialize
2938 an argument. */
2940 {
2941 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2944 #else
2946 #endif
2948 {
2950 NULL_RTX);
2954 /* stack_arg_under_construction says whether a stack
2955 arg is being constructed at the old stack level.
2956 Pushing the stack gets a clean outgoing argument
2957 block. */
2958 old_stack_arg_under_construction
2961 /* Make a new map for the new argument list. */
2965 }
2967 BITS_PER_UNIT);
2968 }
2970 /* If argument evaluation might modify the stack pointer,
2971 copy the address of the argument list to a register. */
2974 {
2977 }
2978 }
2982 /* If we push args individually in reverse order, perform stack alignment
2983 before the first push (the last arg). */
2986 {
2987 /* When the stack adjustment is pending, we get better code
2988 by combining the adjustments. */
2992 {
2993 pending_stack_adjust
2994 = (combine_pending_stack_adjustment_and_call
2997 preferred_unit_stack_boundary));
2999 }
3003 }
3004 /* Now that the stack is properly aligned, pops can't safely
3005 be deferred during the evaluation of the arguments. */
3006 NO_DEFER_POP;
3010 /* Figure out the register where the value, if any, will come back. */
3014 {
3018 else
3020 }
3022 /* Precompute all register parameters. It isn't safe to compute anything
3023 once we have started filling any specific hard regs. */
3026 #ifdef REG_PARM_STACK_SPACE
3027 /* Save the fixed argument area if it's part of the caller's frame and
3028 is clobbered by argument setup for this call. */
3032 #endif
3034 /* Now store (and compute if necessary) all non-register parms.
3035 These come before register parms, since they can require block-moves,
3036 which could clobber the registers used for register parms.
3037 Parms which have partial registers are not stored here,
3038 but we do preallocate space here if they want that. */
3042 {
3047 reg_parm_stack_space)
3059 call_fusage);
3060 }
3062 /* If we have a parm that is passed in registers but not in memory
3063 and whose alignment does not permit a direct copy into registers,
3064 make a group of pseudos that correspond to each register that we
3065 will later fill. */
3069 /* Now store any partially-in-registers parm.
3070 This is the last place a block-move can happen. */
3074 {
3079 reg_parm_stack_space)
3084 }
3086 /* If we pushed args in forward order, perform stack alignment
3087 after pushing the last arg. */
3092 /* If register arguments require space on the stack and stack space
3093 was not preallocated, allocate stack space here for arguments
3094 passed in registers. */
3095 #ifdef OUTGOING_REG_PARM_STACK_SPACE
3099 #endif
3101 /* Pass the function the address in which to return a
3102 structure value. */
3104 {
3105 structure_value_addr
3110 NULL_RTX)));
3114 }
3122 /* Perform postincrements before actually calling the function. */
3125 /* Save a pointer to the last insn before the call, so that we can
3126 later safely search backwards to find the CALL_INSN. */
3129 /* Set up next argument register. For sibling calls on machines
3130 with register windows this should be the incoming register. */
3131 #ifdef FUNCTION_INCOMING_ARG
3135 else
3136 #endif
3140 /* All arguments and registers used for the call must be set up by
3141 now! */
3143 /* Stack must be properly aligned now. */
3147 /* Generate the actual call instruction. */
3153 /* If call is cse'able, make appropriate pair of reg-notes around it.
3154 Test valreg so we don't crash; may safely ignore `const'
3155 if return type is void. Disable for PARALLEL return values, because
3156 we have no way to move such values into a pseudo register. */
3158 {
3159 rtx insns;
3160 rtx insn;
3165 /* Expansion of block moves possibly introduced a loop that may
3166 not appear inside libcall block. */
3172 {
3175 }
3176 else
3177 {
3181 /* Mark the return value as a pointer if needed. */
3188 && fndecl
3196 else
3197 {
3198 /* Construct an "equal form" for the value which
3199 mentions all the arguments in order as well as
3200 the function name. */
3211 note);
3212 }
3216 }
3217 }
3219 {
3223 /* The return value from a malloc-like function is a pointer. */
3229 /* The return value from a malloc-like function can not alias
3230 anything else. */
3235 /* Write out the sequence. */
3240 }
3242 /* For calls to `setjmp', etc., inform flow.c it should complain
3243 if nonvolatile values are live. For functions that cannot return,
3244 inform flow that control does not fall through. */
3247 {
3248 /* The barrier must be emitted
3249 immediately after the CALL_INSN. Some ports emit more
3250 than just a CALL_INSN above, so we must search for it here. */
3254 {
3256 /* There was no CALL_INSN? */
3259 }
3263 /* Stack adjustments after a noreturn call are dead code.
3264 However when NO_DEFER_POP is in effect, we must preserve
3265 stack_pointer_delta. */
3267 {
3270 }
3271 }
3276 /* If value type not void, return an rtx for the value. */
3278 /* If there are cleanups to be called, don't use a hard reg as target.
3279 We need to double check this and see if it matters anymore. */
3281 {
3286 }
3292 {
3294 {
3295 target
3298 structure_value_addr));
3300 }
3301 }
3303 {
3304 /* This is the special C++ case where we need to
3305 know what the true target was. We take care to
3306 never use this value more than once in one expression. */
3310 }
3311 /* Handle calls that return values in multiple non-contiguous locations.
3312 The Irix 6 ABI has examples of this. */
3314 {
3315 /* Second condition is added because "target" is freed at the
3316 the end of "pass0" for -O2 when call is made to
3317 expand_end_target_temps (). Its "in_use" flag has been set
3318 to false, so allocate a new temp. */
3320 {
3321 /* This will only be assigned once, so it can be readonly. */
3329 }
3335 /* We can not support sibling calls for this case. */
3337 }
3341 {
3342 /* TARGET and VALREG cannot be equal at this point because the
3343 latter would not have REG_FUNCTION_VALUE_P true, while the
3344 former would if it were referring to the same register.
3346 If they refer to the same register, this move will be a no-op,
3347 except when function inlining is being done. */
3350 /* If we are setting a MEM, this code must be executed. Since it is
3351 emitted after the call insn, sibcall optimization cannot be
3352 performed in that case. */
3355 }
3357 {
3360 /* We can not support sibling calls for this case. */
3362 }
3363 else
3364 {
3369 }
3372 {
3373 /* If we promoted this return value, make the proper SUBREG. TARGET
3374 might be const0_rtx here, so be careful. */
3378 {
3383 /* If we don't promote as expected, something is wrong. */
3391 {
3398 }
3402 }
3403 }
3405 /* If size of args is variable or this was a constructor call for a stack
3406 argument, restore saved stack-pointer value. */
3409 {
3417 }
3419 {
3420 #ifdef REG_PARM_STACK_SPACE
3424 #endif
3426 /* If we saved any argument areas, restore them. */
3429 {
3431 rtx stack_area
3438 else
3441 BLOCK_OP_CALL_PARM);
3442 }
3446 }
3448 /* If this was alloca, record the new stack level for nonlocal gotos.
3449 Check for the handler slots since we might not have a save area
3450 for non-local gotos. */
3455 /* Free up storage we no longer need. */
3461 {
3462 /* Undo the fake expand_start_target_temps we did earlier. If
3463 there had been any cleanups created, we've already set
3464 sibcall_failure. */
3466 }
3468 /* If this function is returning into a memory location marked as
3469 readonly, it means it is initializing that location. We normally treat
3470 functions as not clobbering such locations, so we need to specify that
3471 this one does. We do this by adding the appropriate CLOBBER to the
3472 CALL_INSN function usage list. This cannot be done by emitting a
3473 standalone CLOBBER after the call because the latter would be ignored
3474 by at least the delay slot scheduling pass. We do this now instead of
3475 adding to call_fusage before the call to emit_call_1 because TARGET
3476 may be modified in the meantime. */
3479 add_function_usage_to
3482 NULL_RTX));
3488 {
3491 /* Restore the pending stack adjustment now that we have
3492 finished generating the sibling call sequence. */
3497 /* Prepare arg structure for next iteration. */
3499 {
3503 }
3506 }
3507 else
3508 {
3511 /* Verify that we've deallocated all the stack we used. */
3516 }
3518 /* If something prevents making this a sibling call,
3519 zero out the sequence. */
3522 }
3524 /* The function optimize_sibling_and_tail_recursive_calls doesn't
3525 handle CALL_PLACEHOLDERs inside other CALL_PLACEHOLDERs. This
3526 can happen if the arguments to this function call an inline
3527 function who's expansion contains another CALL_PLACEHOLDER.
3529 If there are any C_Ps in any of these sequences, replace them
3530 with their normal call. */
3547 /* If this was a potential tail recursion site, then emit a
3548 CALL_PLACEHOLDER with the normal and the tail recursion streams.
3549 One of them will be selected later. */
3551 {
3552 /* The tail recursion label must be kept around. We could expose
3553 its use in the CALL_PLACEHOLDER, but that creates unwanted edges
3554 and makes determining true tail recursion sites difficult.
3556 So we set LABEL_PRESERVE_P here, then clear it when we select
3557 one of the call sequences after rtl generation is complete. */
3561 tail_call_insns,
3562 tail_recursion_insns,
3563 tail_recursion_label));
3564 }
3565 else
3568 currently_expanding_call--;
3570 /* If this function returns with the stack pointer depressed, ensure
3571 this block saves and restores the stack pointer, show it was
3572 changed, and adjust for any outgoing arg space. */
3574 {
3579 }
3582 }
3584 /* Traverse an argument list in VALUES and expand all complex
3585 arguments into their components. */
3586 tree
3588 {
3589 tree p;
3591 /* Before allocating memory, check for the common case of no complex. */
3593 {
3598 }
3601 found:
3605 {
3607 tree complex_type;
3615 {
3616 tree subtype;
3630 /* Skip the newly created node. */
3632 }
3633 }
3636 }
3638 /* Traverse a list of TYPES and expand all complex types into their
3639 components. */
3640 tree
3642 {
3643 tree p;
3645 /* Before allocating memory, check for the common case of no complex. */
3647 {
3652 }
3655 found:
3659 {
3664 {
3667 /* Rewrite complex type with component type. */
3671 /* Add another component type for the imaginary part. */
3676 /* Skip the newly created node. */
3678 }
3679 }
3682 }
3683 \f
3684 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3685 The RETVAL parameter specifies whether return value needs to be saved, other
3686 parameters are documented in the emit_library_call function below. */
3688 static rtx
3692 {
3693 /* Total size in bytes of all the stack-parms scanned so far. */
3695 /* Size of arguments before any adjustments (such as rounding). */
3698 rtx fun;
3702 CUMULATIVE_ARGS args_so_far;
3703 struct arg
3704 {
3705 rtx value;
3707 rtx reg;
3710 rtx save_area;
3711 };
3716 rtx valreg;
3722 rtx before_call;
3725 #ifdef REG_PARM_STACK_SPACE
3726 /* Define the boundary of the register parm stack space that needs to be
3727 save, if any. */
3730 #endif
3732 /* Size of the stack reserved for parameter registers. */
3738 #ifdef REG_PARM_STACK_SPACE
3739 #ifdef MAYBE_REG_PARM_STACK_SPACE
3741 #else
3743 #endif
3744 #endif
3746 /* By default, library functions can not throw. */
3750 {
3777 }
3780 /* Ensure current function's preferred stack boundary is at least
3781 what we need. */
3785 /* If this kind of value comes back in memory,
3786 decide where in memory it should come back. */
3788 {
3791 {
3792 #ifdef PCC_STATIC_STRUCT_RETURN
3793 rtx pointer_reg
3803 else
3805 #endif
3806 /* This call returns a big structure. */
3808 }
3809 }
3810 else
3813 /* ??? Unfinished: must pass the memory address as an argument. */
3815 /* Copy all the libcall-arguments out of the varargs data
3816 and into a vector ARGVEC.
3818 Compute how to pass each argument. We only support a very small subset
3819 of the full argument passing conventions to limit complexity here since
3820 library functions shouldn't have many args. */
3825 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3827 #else
3829 #endif
3836 /* Now we are about to start emitting insns that can be deleted
3837 if a libcall is deleted. */
3843 /* If there's a structure value address to be passed,
3844 either pass it in the special place, or pass it as an extra argument. */
3846 {
3848 nargs++;
3850 /* Make sure it is a reasonable operand for a move or push insn. */
3860 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3863 #endif
3866 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3868 #else
3870 #endif
3879 count++;
3880 }
3883 {
3887 /* We cannot convert the arg value to the mode the library wants here;
3888 must do it earlier where we know the signedness of the arg. */
3893 /* There's no need to call protect_from_queue, because
3894 either emit_move_insn or emit_push_insn will do that. */
3896 /* Make sure it is a reasonable operand for a move or push insn. */
3901 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
3903 {
3904 rtx slot;
3906 #ifdef FUNCTION_ARG_CALLEE_COPIES
3909 #endif
3910 ;
3912 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3913 functions, so we have to pretend this isn't such a function. */
3915 {
3919 }
3922 /* If this was a CONST function, it is now PURE since
3923 it now reads memory. */
3925 {
3928 }
3933 {
3937 }
3938 else
3939 {
3942 slot
3948 }
3952 call_fusage);
3956 slot),
3957 call_fusage);
3961 }
3962 #endif
3969 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3972 #else
3974 #endif
3977 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3979 #else
3981 #endif
3993 }
3995 #ifdef FINAL_REG_PARM_STACK_SPACE
3998 #endif
3999 /* If this machine requires an external definition for library
4000 functions, write one out. */
4005 + stack_pointer_delta
4007 / STACK_BYTES
4012 reg_parm_stack_space);
4014 #ifndef OUTGOING_REG_PARM_STACK_SPACE
4016 #endif
4022 {
4023 /* Since the stack pointer will never be pushed, it is possible for
4024 the evaluation of a parm to clobber something we have already
4025 written to the stack. Since most function calls on RISC machines
4026 do not use the stack, this is uncommon, but must work correctly.
4028 Therefore, we save any area of the stack that was already written
4029 and that we are using. Here we set up to do this by making a new
4030 stack usage map from the old one.
4032 Another approach might be to try to reorder the argument
4033 evaluations to avoid this conflicting stack usage. */
4037 #ifndef OUTGOING_REG_PARM_STACK_SPACE
4038 /* Since we will be writing into the entire argument area, the
4039 map must be allocated for its entire size, not just the part that
4040 is the responsibility of the caller. */
4042 #endif
4044 #ifdef ARGS_GROW_DOWNWARD
4047 #else
4049 needed);
4050 #endif
4055 initial_highest_arg_in_use);
4062 /* We must be careful to use virtual regs before they're instantiated,
4063 and real regs afterwards. Loop optimization, for example, can create
4064 new libcalls after we've instantiated the virtual regs, and if we
4065 use virtuals anyway, they won't match the rtl patterns. */
4069 else
4071 }
4072 else
4073 {
4076 }
4078 /* If we push args individually in reverse order, perform stack alignment
4079 before the first push (the last arg). */
4085 {
4088 }
4089 else
4090 {
4093 }
4095 #ifdef REG_PARM_STACK_SPACE
4097 {
4098 /* The argument list is the property of the called routine and it
4099 may clobber it. If the fixed area has been used for previous
4100 parameters, we must save and restore it. */
4103 }
4104 #endif
4106 /* Push the args that need to be pushed. */
4108 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4109 are to be pushed. */
4111 {
4119 {
4121 {
4122 /* If this is being stored into a pre-allocated, fixed-size,
4123 stack area, save any previous data at that location. */
4125 #ifdef ARGS_GROW_DOWNWARD
4126 /* stack_slot is negative, but we want to index stack_usage_map
4127 with positive values. */
4130 #else
4133 #endif
4136 /* Don't worry about things in the fixed argument area;
4137 it has already been saved. */
4141 i++;
4144 {
4145 /* We need to make a save area. */
4146 unsigned int size
4148 enum machine_mode save_mode
4150 rtx adr
4153 rtx stack_area
4157 {
4164 stack_area,
4166 BLOCK_OP_CALL_PARM);
4167 }
4168 else
4169 {
4173 }
4174 }
4175 }
4180 reg_parm_stack_space,
4183 /* Now mark the segment we just used. */
4188 NO_DEFER_POP;
4189 }
4190 }
4192 /* If we pushed args in forward order, perform stack alignment
4193 after pushing the last arg. */
4200 else
4205 /* Now load any reg parms into their regs. */
4207 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4208 are to be pushed. */
4210 {
4215 /* Handle calls that pass values in multiple non-contiguous
4216 locations. The PA64 has examples of this for library calls. */
4222 NO_DEFER_POP;
4223 }
4225 /* Any regs containing parms remain in use through the call. */
4227 {
4233 }
4235 /* Pass the function the address in which to return a structure value. */
4237 {
4241 NULL_RTX)));
4244 }
4246 /* Don't allow popping to be deferred, since then
4247 cse'ing of library calls could delete a call and leave the pop. */
4248 NO_DEFER_POP;
4252 /* Stack must be properly aligned now. */
4258 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4259 will set inhibit_defer_pop to that value. */
4260 /* The return type is needed to decide how many bytes the function pops.
4261 Signedness plays no role in that, so for simplicity, we pretend it's
4262 always signed. We also assume that the list of arguments passed has
4263 no impact, so we pretend it is unknown. */
4269 struct_value_size,
4271 valreg,
4274 /* For calls to `setjmp', etc., inform flow.c it should complain
4275 if nonvolatile values are live. For functions that cannot return,
4276 inform flow that control does not fall through. */
4279 {
4280 /* The barrier note must be emitted
4281 immediately after the CALL_INSN. Some ports emit more than
4282 just a CALL_INSN above, so we must search for it here. */
4286 {
4288 /* There was no CALL_INSN? */
4291 }
4294 }
4296 /* Now restore inhibit_defer_pop to its actual original value. */
4297 OK_DEFER_POP;
4299 /* If call is cse'able, make appropriate pair of reg-notes around it.
4300 Test valreg so we don't crash; may safely ignore `const'
4301 if return type is void. Disable for PARALLEL return values, because
4302 we have no way to move such values into a pseudo register. */
4304 {
4305 rtx insns;
4308 {
4312 }
4313 else
4314 {
4316 rtx temp;
4320 {
4325 }
4329 /* Construct an "equal form" for the value which mentions all the
4330 arguments in order as well as the function name. */
4343 note);
4348 }
4349 }
4352 /* Copy the value to the right place. */
4354 {
4356 {
4361 }
4363 {
4367 }
4370 else
4372 }
4375 {
4376 #ifdef REG_PARM_STACK_SPACE
4380 #endif
4382 /* If we saved any argument areas, restore them. */
4385 {
4396 BLOCK_OP_CALL_PARM);
4397 else
4399 }
4403 }
4407 }
4408 \f
4409 /* Output a library call to function FUN (a SYMBOL_REF rtx)
4410 (emitting the queue unless NO_QUEUE is nonzero),
4411 for a value of mode OUTMODE,
4412 with NARGS different arguments, passed as alternating rtx values
4413 and machine_modes to convert them to.
4414 The rtx values should have been passed through protect_from_queue already.
4416 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
4417 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
4418 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
4419 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
4420 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
4421 or other LCT_ value for other types of library calls. */
4423 void
4426 {
4432 }
4433 \f
4434 /* Like emit_library_call except that an extra argument, VALUE,
4435 comes second and says where to store the result.
4436 (If VALUE is zero, this function chooses a convenient way
4437 to return the value.
4439 This function returns an rtx for where the value is to be found.
4440 If VALUE is nonzero, VALUE is returned. */
4442 rtx
4446 {
4447 rtx result;
4456 }
4457 \f
4458 /* Store a single argument for a function call
4459 into the register or memory area where it must be passed.
4460 *ARG describes the argument value and where to pass it.
4462 ARGBLOCK is the address of the stack-block for all the arguments,
4463 or 0 on a machine where arguments are pushed individually.
4465 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4466 so must be careful about how the stack is used.
4468 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4469 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4470 that we need not worry about saving and restoring the stack.
4472 FNDECL is the declaration of the function we are calling.
4474 Return nonzero if this arg should cause sibcall failure,
4475 zero otherwise. */
4477 static int
4480 {
4491 /* Push a new temporary level for any temporaries we make for
4492 this argument. */
4496 {
4497 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4498 save any previous data at that location. */
4500 {
4501 #ifdef ARGS_GROW_DOWNWARD
4502 /* stack_slot is negative, but we want to index stack_usage_map
4503 with positive values. */
4506 else
4510 #else
4513 else
4517 #endif
4520 /* Don't worry about things in the fixed argument area;
4521 it has already been saved. */
4525 i++;
4528 {
4529 /* We need to make a save area. */
4536 {
4545 BLOCK_OP_CALL_PARM);
4546 }
4547 else
4548 {
4551 }
4552 }
4553 }
4554 }
4556 /* If this isn't going to be placed on both the stack and in registers,
4557 set up the register and number of words. */
4559 {
4562 else
4565 }
4568 /* Being passed entirely in a register. We shouldn't be called in
4569 this case. */
4572 /* If this arg needs special alignment, don't load the registers
4573 here. */
4577 /* If this is being passed partially in a register, we can't evaluate
4578 it directly into its stack slot. Otherwise, we can. */
4580 {
4581 /* stack_arg_under_construction is nonzero if a function argument is
4582 being evaluated directly into the outgoing argument list and
4583 expand_call must take special action to preserve the argument list
4584 if it is called recursively.
4586 For scalar function arguments stack_usage_map is sufficient to
4587 determine which stack slots must be saved and restored. Scalar
4588 arguments in general have pass_on_stack == 0.
4590 If this argument is initialized by a function which takes the
4591 address of the argument (a C++ constructor or a C function
4592 returning a BLKmode structure), then stack_usage_map is
4593 insufficient and expand_call must push the stack around the
4594 function call. Such arguments have pass_on_stack == 1.
4596 Note that it is always safe to set stack_arg_under_construction,
4597 but this generates suboptimal code if set when not needed. */
4600 stack_arg_under_construction++;
4603 (partial
4608 /* If we are promoting object (or for any other reason) the mode
4609 doesn't agree, convert the mode. */
4616 stack_arg_under_construction--;
4617 }
4619 /* Don't allow anything left on stack from computation
4620 of argument to alloca. */
4625 /* If the value is already in the stack slot, we are done. */
4626 ;
4628 {
4631 /* Argument is a scalar, not entirely passed in registers.
4632 (If part is passed in registers, arg->partial says how much
4633 and emit_push_insn will take care of putting it there.)
4635 Push it, and if its size is less than the
4636 amount of space allocated to it,
4637 also bump stack pointer by the additional space.
4638 Note that in C the default argument promotions
4639 will prevent such mismatches. */
4642 /* Compute how much space the push instruction will push.
4643 On many machines, pushing a byte will advance the stack
4644 pointer by a halfword. */
4645 #ifdef PUSH_ROUNDING
4647 #endif
4650 /* Compute how much space the argument should get:
4651 round up to a multiple of the alignment for arguments. */
4657 /* This isn't already where we want it on the stack, so put it there.
4658 This can either be done with push or copy insns. */
4664 /* Unless this is a partially-in-register argument, the argument is now
4665 in the stack. */
4668 }
4669 else
4670 {
4671 /* BLKmode, at least partly to be pushed. */
4675 rtx size_rtx;
4677 /* Pushing a nonscalar.
4678 If part is passed in registers, PARTIAL says how much
4679 and emit_push_insn will take care of putting it there. */
4681 /* Round its size up to a multiple
4682 of the allocation unit for arguments. */
4685 {
4688 }
4689 else
4690 {
4691 /* PUSH_ROUNDING has no effect on us, because
4692 emit_push_insn for BLKmode is careful to avoid it. */
4694 {
4695 /* Use the size of the elt to compute excess. */
4700 }
4701 else
4707 }
4709 /* Some types will require stricter alignment, which will be
4710 provided for elsewhere in argument layout. */
4713 /* When an argument is padded down, the block is aligned to
4714 PARM_BOUNDARY, but the actual argument isn't. */
4716 {
4720 {
4723 }
4724 }
4727 {
4728 /* emit_push_insn might not work properly if arg->value and
4729 argblock + arg->locate.offset areas overlap. */
4736 current_function_internal_arg_pointer
4738 {
4742 /* expand_call should ensure this. */
4747 {
4750 }
4752 {
4755 }
4756 }
4757 }
4764 /* Unless this is a partially-in-register argument, the argument is now
4765 in the stack.
4767 ??? Unlike the case above, in which we want the actual
4768 address of the data, so that we can load it directly into a
4769 register, here we want the address of the stack slot, so that
4770 it's properly aligned for word-by-word copying or something
4771 like that. It's not clear that this is always correct. */
4774 }
4776 /* Mark all slots this store used. */
4782 /* Once we have pushed something, pops can't safely
4783 be deferred during the rest of the arguments. */
4784 NO_DEFER_POP;
4786 /* ANSI doesn't require a sequence point here,
4787 but PCC has one, so this will avoid some problems. */
4790 /* Free any temporary slots made in processing this argument. Show
4791 that we might have taken the address of something and pushed that
4792 as an operand. */
4798 }
4800 /* Nonzero if we do not know how to pass TYPE solely in registers.
4801 We cannot do so in the following cases:
4803 - if the type has variable size
4804 - if the type is marked as addressable (it is required to be constructed
4805 into the stack)
4806 - if the padding and mode of the type is such that a copy into a register
4807 would put it into the wrong part of the register.
4809 Which padding can't be supported depends on the byte endianness.
4811 A value in a register is implicitly padded at the most significant end.
4812 On a big-endian machine, that is the lower end in memory.
4813 So a value padded in memory at the upper end can't go in a register.
4814 For a little-endian machine, the reverse is true. */
4816 bool
4818 {
4822 /* If the type has variable size... */
4826 /* If the type is marked as addressable (it is required
4827 to be constructed into the stack)... */
4831 /* If the padding and mode of the type is such that a copy into
4832 a register would put it into the wrong part of the register. */
4840 }