| blob | d702ed0d3a61eb3cedac4c80c718d8d46f3604fb |
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. */
1722 else
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 rtx insn;
2088 /* Register in which non-BLKmode value will be returned,
2089 or 0 if no value or if value is BLKmode. */
2090 rtx valreg;
2091 /* Address where we should return a BLKmode value;
2092 0 if value not BLKmode. */
2094 /* Nonzero if that address is being passed by treating it as
2095 an extra, implicit first parameter. Otherwise,
2096 it is passed by being copied directly into struct_value_rtx. */
2098 /* Size of aggregate value wanted, or zero if none wanted
2099 or if we are using the non-reentrant PCC calling convention
2100 or expecting the value in registers. */
2102 /* Nonzero if called function returns an aggregate in memory PCC style,
2103 by returning the address of where to find it. */
2107 /* Number of actual parameters in this call, including struct value addr. */
2109 /* Number of named args. Args after this are anonymous ones
2110 and they must all go on the stack. */
2113 /* Vector of information about each argument.
2114 Arguments are numbered in the order they will be pushed,
2115 not the order they are written. */
2118 /* Total size in bytes of all the stack-parms scanned so far. */
2121 /* Size of arguments before any adjustments (such as rounding). */
2123 /* Data on reg parms scanned so far. */
2124 CUMULATIVE_ARGS args_so_far;
2125 /* Nonzero if a reg parm has been scanned. */
2127 /* Nonzero if this is an indirect function call. */
2129 /* Nonzero if we must avoid push-insns in the args for this call.
2130 If stack space is allocated for register parameters, but not by the
2131 caller, then it is preallocated in the fixed part of the stack frame.
2132 So the entire argument block must then be preallocated (i.e., we
2133 ignore PUSH_ROUNDING in that case). */
2137 /* Size of the stack reserved for parameter registers. */
2140 /* Address of space preallocated for stack parms
2141 (on machines that lack push insns), or 0 if space not preallocated. */
2144 /* Mask of ECF_ flags. */
2146 /* Nonzero if this is a call to an inline function. */
2148 #ifdef REG_PARM_STACK_SPACE
2149 /* Define the boundary of the register parm stack space that needs to be
2150 saved, if any. */
2153 #endif
2161 /* State variables to track stack modifications. */
2167 /* Some stack pointer alterations we make are performed via
2168 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2169 which we then also need to save/restore along the way. */
2172 rtx call_fusage;
2176 /* The alignment of the stack, in bits. */
2177 HOST_WIDE_INT preferred_stack_boundary;
2178 /* The alignment of the stack, in bytes. */
2179 HOST_WIDE_INT preferred_unit_stack_boundary;
2181 /* See if this is "nothrow" function call. */
2185 /* See if we can find a DECL-node for the actual function.
2186 As a result, decide whether this is a call to an integrable function. */
2190 {
2198 {
2199 /* In case this function later becomes inlinable,
2200 record that there was already a non-inline call to it.
2202 Use abstraction instead of setting TREE_ADDRESSABLE
2203 directly. */
2206 {
2209 }
2211 }
2220 }
2222 /* If we don't have specific function to call, see if we have a
2223 attributes set in the type. */
2224 else
2225 {
2232 }
2236 /* Warn if this value is an aggregate type,
2237 regardless of which calling convention we are using for it. */
2241 /* If the result of a pure or const function call is ignored (or void),
2242 and none of its arguments are volatile, we can avoid expanding the
2243 call and just evaluate the arguments for side-effects. */
2247 {
2249 tree arg;
2253 {
2256 }
2259 {
2264 }
2265 }
2267 #ifdef REG_PARM_STACK_SPACE
2268 #ifdef MAYBE_REG_PARM_STACK_SPACE
2270 #else
2272 #endif
2273 #endif
2275 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2278 #endif
2280 /* Set up a place to return a structure. */
2282 /* Cater to broken compilers. */
2284 {
2285 /* This call returns a big structure. */
2288 #ifdef PCC_STATIC_STRUCT_RETURN
2289 {
2291 /* Easier than making that case work right. */
2293 {
2294 /* In case this is a static function, note that it has been
2295 used. */
2299 }
2300 }
2302 {
2306 {
2307 /* The structure value address arg is already in actparms.
2308 Pull it out. It might be nice to just leave it there, but
2309 we need to set structure_value_addr. */
2314 }
2317 else
2318 {
2319 /* For variable-sized objects, we must be called with a target
2320 specified. If we were to allocate space on the stack here,
2321 we would have no way of knowing when to free it. */
2327 }
2328 }
2330 }
2332 /* If called function is inline, try to integrate it. */
2335 {
2338 structure_value_addr);
2341 }
2343 /* Figure out the amount to which the stack should be aligned. */
2346 {
2350 }
2352 /* Operand 0 is a pointer-to-function; get the type of the function. */
2358 /* Munge the tree to split complex arguments into their imaginary
2359 and real parts. */
2361 {
2364 }
2365 else
2368 /* See if this is a call to a function that can return more than once
2369 or a call to longjmp or malloc. */
2375 /* If struct_value_rtx is 0, it means pass the address
2376 as if it were an extra parameter. */
2378 {
2379 /* If structure_value_addr is a REG other than
2380 virtual_outgoing_args_rtx, we can use always use it. If it
2381 is not a REG, we must always copy it into a register.
2382 If it is virtual_outgoing_args_rtx, we must copy it to another
2383 register in some cases. */
2385 || (ACCUMULATE_OUTGOING_ARGS
2386 && stack_arg_under_construction
2391 actparms
2394 temp),
2395 actparms);
2397 }
2399 /* Count the arguments and set NUM_ACTUALS. */
2401 num_actuals++;
2403 /* Compute number of named args.
2404 Normally, don't include the last named arg if anonymous args follow.
2405 We do include the last named arg if
2406 targetm.calls.strict_argument_naming() returns nonzero.
2407 (If no anonymous args follow, the result of list_length is actually
2408 one too large. This is harmless.)
2410 If targetm.calls.pretend_outgoing_varargs_named() returns
2411 nonzero, and targetm.calls.strict_argument_naming() returns zero,
2412 this machine will be able to place unnamed args that were passed
2413 in registers into the stack. So treat all args as named. This
2414 allows the insns emitting for a specific argument list to be
2415 independent of the function declaration.
2417 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
2418 we do not have any reliable way to pass unnamed args in
2419 registers, so we must force them into memory. */
2424 n_named_args
2426 /* Don't include the last named arg. */
2428 /* Count the struct value address, if it is passed as a parm. */
2430 else
2431 /* If we know nothing, treat all args as named. */
2434 /* Start updating where the next arg would go.
2436 On some machines (such as the PA) indirect calls have a different
2437 calling convention than normal calls. The fourth argument in
2438 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2439 or not. */
2442 /* Make a vector to hold all the information about each arg. */
2446 /* Build up entries in the ARGS array, compute the size of the
2447 arguments into ARGS_SIZE, etc. */
2456 {
2457 /* If this function requires a variable-sized argument list, don't
2458 try to make a cse'able block for this call. We may be able to
2459 do this eventually, but it is too complicated to keep track of
2460 what insns go in the cse'able block and which don't. */
2464 }
2466 /* Now make final decision about preallocating stack space. */
2471 /* If the structure value address will reference the stack pointer, we
2472 must stabilize it. We don't need to do this if we know that we are
2473 not going to adjust the stack pointer in processing this call. */
2478 structure_value_addr))
2483 /* Tail calls can make things harder to debug, and we're traditionally
2484 pushed these optimizations into -O2. Don't try if we're already
2485 expanding a call, as that means we're an argument. Don't try if
2486 there's cleanups, as we know there's code to follow the call.
2488 If rtx_equal_function_value_matters is false, that means we've
2489 finished with regular parsing. Which means that some of the
2490 machinery we use to generate tail-calls is no longer in place.
2491 This is most often true of sjlj-exceptions, which we couldn't
2492 tail-call to anyway.
2494 If current_nesting_level () == 0, we're being called after
2495 the function body has been expanded. This can happen when
2496 setting up trampolines in expand_function_end. */
2498 || !flag_optimize_sibling_calls
2499 || !rtx_equal_function_value_matters
2505 /* Tail recursion fails, when we are not dealing with recursive calls. */
2511 /* Rest of purposes for tail call optimizations to fail. */
2513 #ifdef HAVE_sibcall_epilogue
2514 !HAVE_sibcall_epilogue
2515 #else
2516 1
2517 #endif
2518 || !try_tail_call
2519 /* Doing sibling call optimization needs some work, since
2520 structure_value_addr can be allocated on the stack.
2521 It does not seem worth the effort since few optimizable
2522 sibling calls will return a structure. */
2524 /* Check whether the target is able to optimize the call
2525 into a sibcall. */
2527 /* Functions that do not return exactly once may not be sibcall
2528 optimized. */
2531 /* If the called function is nested in the current one, it might access
2532 some of the caller's arguments, but could clobber them beforehand if
2533 the argument areas are shared. */
2535 /* If this function requires more stack slots than the current
2536 function, we cannot change it into a sibling call. */
2538 /* If the callee pops its own arguments, then it must pop exactly
2539 the same number of arguments as the current function. */
2543 current_function_args_size))
2548 {
2551 /* Ok, we're going to give the tail call the old college try.
2552 This means we're going to evaluate the function arguments
2553 up to three times. There are two degrees of badness we can
2554 encounter, those that can be unsaved and those that can't.
2555 (See unsafe_for_reeval commentary for details.)
2557 Generate a new argument list. Pass safe arguments through
2558 unchanged. For the easy badness wrap them in UNSAVE_EXPRs.
2559 For hard badness, evaluate them now and put their resulting
2560 rtx in a temporary VAR_DECL.
2562 initialize_argument_information has ordered the array for the
2563 order to be pushed, and we must remember this when reconstructing
2564 the original argument order. */
2567 {
2571 }
2572 else
2573 {
2577 }
2580 {
2582 /* We need to build actparms for optimize_tail_recursion. We can
2583 safely trash away TREE_PURPOSE, since it is unused by this
2584 function. */
2587 }
2588 /* Do the same for the function address if it is an expression. */
2591 /* Expanding one of those dangerous arguments could have added
2592 cleanups, but otherwise give it a whirl. */
2595 }
2597 /* Generate a tail recursion sequence when calling ourselves. */
2600 {
2601 /* We want to emit any pending stack adjustments before the tail
2602 recursion "call". That way we know any adjustment after the tail
2603 recursion call can be ignored if we indeed use the tail recursion
2604 call expansion. */
2608 /* Emit any queued insns now; otherwise they would end up in
2609 only one of the alternates. */
2612 /* Use a new sequence to hold any RTL we generate. We do not even
2613 know if we will use this RTL yet. The final decision can not be
2614 made until after RTL generation for the entire function is
2615 complete. */
2617 /* If expanding any of the arguments creates cleanups, we can't
2618 do a tailcall. So, we'll need to pop the pending cleanups
2619 list. If, however, all goes well, and there are no cleanups
2620 then the call to expand_start_target_temps will have no
2621 effect. */
2624 {
2627 else
2629 }
2633 /* Restore the original pending stack adjustment for the sibling and
2634 normal call cases below. */
2637 }
2640 {
2641 /* A fork duplicates the profile information, and an exec discards
2642 it. We can't rely on fork/exec to be paired. So write out the
2643 profile information we have gathered so far, and clear it. */
2644 /* ??? When Linux's __clone is called with CLONE_VM set, profiling
2645 is subject to race conditions, just as with multithreaded
2646 programs. */
2649 }
2651 /* Ensure current function's preferred stack boundary is at least
2652 what we need. We don't have to increase alignment for recursive
2653 functions. */
2662 function_call_count++;
2664 /* We want to make two insn chains; one for a sibling call, the other
2665 for a normal call. We will select one of the two chains after
2666 initial RTL generation is complete. */
2668 {
2670 /* We want to emit any pending stack adjustments before the tail
2671 recursion "call". That way we know any adjustment after the tail
2672 recursion call can be ignored if we indeed use the tail recursion
2673 call expansion. */
2676 rtx insns;
2680 {
2681 /* Emit any queued insns now; otherwise they would end up in
2682 only one of the alternates. */
2685 /* State variables we need to save and restore between
2686 iterations. */
2689 }
2692 else
2695 /* Other state variables that we must reinitialize each time
2696 through the loop (that are not initialized by the loop itself). */
2700 /* Start a new sequence for the normal call case.
2702 From this point on, if the sibling call fails, we want to set
2703 sibcall_failure instead of continuing the loop. */
2707 {
2708 /* We know at this point that there are not currently any
2709 pending cleanups. If, however, in the process of evaluating
2710 the arguments we were to create some, we'll need to be
2711 able to get rid of them. */
2713 }
2715 /* Don't let pending stack adjusts add up to too much.
2716 Also, do all pending adjustments now if there is any chance
2717 this might be a call to alloca or if we are expanding a sibling
2718 call sequence or if we are calling a function that is to return
2719 with stack pointer depressed. */
2726 /* When calling a const function, we must pop the stack args right away,
2727 so that the pop is deleted or moved with the call. */
2729 NO_DEFER_POP;
2731 #ifdef FINAL_REG_PARM_STACK_SPACE
2734 #endif
2735 /* Precompute any arguments as needed. */
2739 /* Now we are about to start emitting insns that can be deleted
2740 if a libcall is deleted. */
2745 /* Compute the actual size of the argument block required. The variable
2746 and constant sizes must be combined, the size may have to be rounded,
2747 and there may be a minimum required size. When generating a sibcall
2748 pattern, do not round up, since we'll be re-using whatever space our
2749 caller provided. */
2750 unadjusted_args_size
2758 /* The argument block when performing a sibling call is the
2759 incoming argument block. */
2761 {
2763 argblock
2764 #ifdef STACK_GROWS_DOWNWARD
2766 #else
2768 #endif
2771 }
2773 /* If we have no actual push instructions, or shouldn't use them,
2774 make space for all args right now. */
2776 {
2778 {
2783 /* stack_arg_under_construction says whether a stack arg is
2784 being constructed at the old stack level. Pushing the stack
2785 gets a clean outgoing argument block. */
2788 }
2790 }
2791 else
2792 {
2793 /* Note that we must go through the motions of allocating an argument
2794 block even if the size is zero because we may be storing args
2795 in the area reserved for register arguments, which may be part of
2796 the stack frame. */
2800 /* Store the maximum argument space used. It will be pushed by
2801 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2802 checking). */
2808 {
2810 {
2811 /* Since the stack pointer will never be pushed, it is
2812 possible for the evaluation of a parm to clobber
2813 something we have already written to the stack.
2814 Since most function calls on RISC machines do not use
2815 the stack, this is uncommon, but must work correctly.
2817 Therefore, we save any area of the stack that was already
2818 written and that we are using. Here we set up to do this
2819 by making a new stack usage map from the old one. The
2820 actual save will be done by store_one_arg.
2822 Another approach might be to try to reorder the argument
2823 evaluations to avoid this conflicting stack usage. */
2825 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2826 /* Since we will be writing into the entire argument area,
2827 the map must be allocated for its entire size, not just
2828 the part that is the responsibility of the caller. */
2830 #endif
2832 #ifdef ARGS_GROW_DOWNWARD
2835 #else
2837 needed);
2838 #endif
2843 initial_highest_arg_in_use);
2847 (highest_outgoing_arg_in_use
2851 /* The address of the outgoing argument list must not be
2852 copied to a register here, because argblock would be left
2853 pointing to the wrong place after the call to
2854 allocate_dynamic_stack_space below. */
2857 }
2858 else
2859 {
2861 {
2862 /* Try to reuse some or all of the pending_stack_adjust
2863 to get this space. */
2864 needed
2865 = (combine_pending_stack_adjustment_and_call
2868 preferred_unit_stack_boundary));
2870 /* combine_pending_stack_adjustment_and_call computes
2871 an adjustment before the arguments are allocated.
2872 Account for them and see whether or not the stack
2873 needs to go up or down. */
2877 {
2878 /* We're releasing stack space. */
2879 /* ??? We can avoid any adjustment at all if we're
2880 already aligned. FIXME. */
2884 }
2885 else
2886 /* We need to allocate space. We'll do that in
2887 push_block below. */
2889 }
2891 /* Special case this because overhead of `push_block' in
2892 this case is non-trivial. */
2895 else
2896 {
2898 #ifdef ARGS_GROW_DOWNWARD
2900 #endif
2901 }
2903 /* We only really need to call `copy_to_reg' in the case
2904 where push insns are going to be used to pass ARGBLOCK
2905 to a function call in ARGS. In that case, the stack
2906 pointer changes value from the allocation point to the
2907 call point, and hence the value of
2908 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2909 as well always do it. */
2911 }
2912 }
2913 }
2916 {
2917 /* The save/restore code in store_one_arg handles all
2918 cases except one: a constructor call (including a C
2919 function returning a BLKmode struct) to initialize
2920 an argument. */
2922 {
2923 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2926 #else
2928 #endif
2930 {
2932 NULL_RTX);
2936 /* stack_arg_under_construction says whether a stack
2937 arg is being constructed at the old stack level.
2938 Pushing the stack gets a clean outgoing argument
2939 block. */
2940 old_stack_arg_under_construction
2943 /* Make a new map for the new argument list. */
2947 }
2949 BITS_PER_UNIT);
2950 }
2952 /* If argument evaluation might modify the stack pointer,
2953 copy the address of the argument list to a register. */
2956 {
2959 }
2960 }
2964 /* If we push args individually in reverse order, perform stack alignment
2965 before the first push (the last arg). */
2968 {
2969 /* When the stack adjustment is pending, we get better code
2970 by combining the adjustments. */
2974 {
2975 pending_stack_adjust
2976 = (combine_pending_stack_adjustment_and_call
2979 preferred_unit_stack_boundary));
2981 }
2985 }
2986 /* Now that the stack is properly aligned, pops can't safely
2987 be deferred during the evaluation of the arguments. */
2988 NO_DEFER_POP;
2992 /* Figure out the register where the value, if any, will come back. */
2996 {
3000 else
3002 }
3004 /* Precompute all register parameters. It isn't safe to compute anything
3005 once we have started filling any specific hard regs. */
3008 #ifdef REG_PARM_STACK_SPACE
3009 /* Save the fixed argument area if it's part of the caller's frame and
3010 is clobbered by argument setup for this call. */
3014 #endif
3016 /* Now store (and compute if necessary) all non-register parms.
3017 These come before register parms, since they can require block-moves,
3018 which could clobber the registers used for register parms.
3019 Parms which have partial registers are not stored here,
3020 but we do preallocate space here if they want that. */
3024 {
3029 reg_parm_stack_space)
3041 call_fusage);
3042 }
3044 /* If we have a parm that is passed in registers but not in memory
3045 and whose alignment does not permit a direct copy into registers,
3046 make a group of pseudos that correspond to each register that we
3047 will later fill. */
3051 /* Now store any partially-in-registers parm.
3052 This is the last place a block-move can happen. */
3056 {
3061 reg_parm_stack_space)
3066 }
3068 /* If we pushed args in forward order, perform stack alignment
3069 after pushing the last arg. */
3074 /* If register arguments require space on the stack and stack space
3075 was not preallocated, allocate stack space here for arguments
3076 passed in registers. */
3077 #ifdef OUTGOING_REG_PARM_STACK_SPACE
3081 #endif
3083 /* Pass the function the address in which to return a
3084 structure value. */
3086 {
3087 structure_value_addr
3092 NULL_RTX)));
3096 }
3104 /* Perform postincrements before actually calling the function. */
3107 /* Save a pointer to the last insn before the call, so that we can
3108 later safely search backwards to find the CALL_INSN. */
3111 /* Set up next argument register. For sibling calls on machines
3112 with register windows this should be the incoming register. */
3113 #ifdef FUNCTION_INCOMING_ARG
3117 else
3118 #endif
3122 /* All arguments and registers used for the call must be set up by
3123 now! */
3125 /* Stack must be properly aligned now. */
3129 /* Generate the actual call instruction. */
3135 /* If call is cse'able, make appropriate pair of reg-notes around it.
3136 Test valreg so we don't crash; may safely ignore `const'
3137 if return type is void. Disable for PARALLEL return values, because
3138 we have no way to move such values into a pseudo register. */
3140 {
3141 rtx insns;
3142 rtx insn;
3147 /* Expansion of block moves possibly introduced a loop that may
3148 not appear inside libcall block. */
3154 {
3157 }
3158 else
3159 {
3163 /* Mark the return value as a pointer if needed. */
3170 && fndecl
3178 else
3179 {
3180 /* Construct an "equal form" for the value which
3181 mentions all the arguments in order as well as
3182 the function name. */
3193 note);
3194 }
3198 }
3199 }
3201 {
3205 /* The return value from a malloc-like function is a pointer. */
3211 /* The return value from a malloc-like function can not alias
3212 anything else. */
3217 /* Write out the sequence. */
3222 }
3224 /* For calls to `setjmp', etc., inform flow.c it should complain
3225 if nonvolatile values are live. For functions that cannot return,
3226 inform flow that control does not fall through. */
3229 {
3230 /* The barrier must be emitted
3231 immediately after the CALL_INSN. Some ports emit more
3232 than just a CALL_INSN above, so we must search for it here. */
3236 {
3238 /* There was no CALL_INSN? */
3241 }
3245 /* Stack adjustments after a noreturn call are dead code.
3246 However when NO_DEFER_POP is in effect, we must preserve
3247 stack_pointer_delta. */
3249 {
3252 }
3253 }
3258 /* If value type not void, return an rtx for the value. */
3260 /* If there are cleanups to be called, don't use a hard reg as target.
3261 We need to double check this and see if it matters anymore. */
3263 {
3268 }
3274 {
3276 {
3277 target
3280 structure_value_addr));
3282 }
3283 }
3285 {
3286 /* This is the special C++ case where we need to
3287 know what the true target was. We take care to
3288 never use this value more than once in one expression. */
3292 }
3293 /* Handle calls that return values in multiple non-contiguous locations.
3294 The Irix 6 ABI has examples of this. */
3296 {
3297 /* Second condition is added because "target" is freed at the
3298 the end of "pass0" for -O2 when call is made to
3299 expand_end_target_temps (). Its "in_use" flag has been set
3300 to false, so allocate a new temp. */
3302 {
3303 /* This will only be assigned once, so it can be readonly. */
3311 }
3317 /* We can not support sibling calls for this case. */
3319 }
3323 {
3324 /* TARGET and VALREG cannot be equal at this point because the
3325 latter would not have REG_FUNCTION_VALUE_P true, while the
3326 former would if it were referring to the same register.
3328 If they refer to the same register, this move will be a no-op,
3329 except when function inlining is being done. */
3332 /* If we are setting a MEM, this code must be executed. Since it is
3333 emitted after the call insn, sibcall optimization cannot be
3334 performed in that case. */
3337 }
3339 {
3342 /* We can not support sibling calls for this case. */
3344 }
3345 else
3346 {
3351 }
3354 {
3355 /* If we promoted this return value, make the proper SUBREG. TARGET
3356 might be const0_rtx here, so be careful. */
3360 {
3365 /* If we don't promote as expected, something is wrong. */
3373 {
3380 }
3384 }
3385 }
3387 /* If size of args is variable or this was a constructor call for a stack
3388 argument, restore saved stack-pointer value. */
3391 {
3399 }
3401 {
3402 #ifdef REG_PARM_STACK_SPACE
3406 #endif
3408 /* If we saved any argument areas, restore them. */
3411 {
3413 rtx stack_area
3420 else
3423 BLOCK_OP_CALL_PARM);
3424 }
3428 }
3430 /* If this was alloca, record the new stack level for nonlocal gotos.
3431 Check for the handler slots since we might not have a save area
3432 for non-local gotos. */
3437 /* Free up storage we no longer need. */
3443 {
3444 /* Undo the fake expand_start_target_temps we did earlier. If
3445 there had been any cleanups created, we've already set
3446 sibcall_failure. */
3448 }
3450 /* If this function is returning into a memory location marked as
3451 readonly, it means it is initializing that location. We normally treat
3452 functions as not clobbering such locations, so we need to specify that
3453 this one does. We do this by adding the appropriate CLOBBER to the
3454 CALL_INSN function usage list. This cannot be done by emitting a
3455 standalone CLOBBER after the call because the latter would be ignored
3456 by at least the delay slot scheduling pass. We do this now instead of
3457 adding to call_fusage before the call to emit_call_1 because TARGET
3458 may be modified in the meantime. */
3461 add_function_usage_to
3464 NULL_RTX));
3470 {
3473 /* Restore the pending stack adjustment now that we have
3474 finished generating the sibling call sequence. */
3479 /* Prepare arg structure for next iteration. */
3481 {
3485 }
3488 }
3489 else
3490 {
3493 /* Verify that we've deallocated all the stack we used. */
3498 }
3500 /* If something prevents making this a sibling call,
3501 zero out the sequence. */
3504 }
3506 /* The function optimize_sibling_and_tail_recursive_calls doesn't
3507 handle CALL_PLACEHOLDERs inside other CALL_PLACEHOLDERs. This
3508 can happen if the arguments to this function call an inline
3509 function who's expansion contains another CALL_PLACEHOLDER.
3511 If there are any C_Ps in any of these sequences, replace them
3512 with their normal call. */
3529 /* If this was a potential tail recursion site, then emit a
3530 CALL_PLACEHOLDER with the normal and the tail recursion streams.
3531 One of them will be selected later. */
3533 {
3534 /* The tail recursion label must be kept around. We could expose
3535 its use in the CALL_PLACEHOLDER, but that creates unwanted edges
3536 and makes determining true tail recursion sites difficult.
3538 So we set LABEL_PRESERVE_P here, then clear it when we select
3539 one of the call sequences after rtl generation is complete. */
3543 tail_call_insns,
3544 tail_recursion_insns,
3545 tail_recursion_label));
3546 }
3547 else
3550 currently_expanding_call--;
3552 /* If this function returns with the stack pointer depressed, ensure
3553 this block saves and restores the stack pointer, show it was
3554 changed, and adjust for any outgoing arg space. */
3556 {
3561 }
3564 }
3566 /* Traverse an argument list in VALUES and expand all complex
3567 arguments into their components. */
3568 tree
3570 {
3571 tree p;
3576 {
3578 tree complex_type;
3585 {
3586 tree subtype;
3600 /* Skip the newly created node. */
3602 }
3603 }
3606 }
3608 /* Traverse a list of TYPES and expand all complex types into their
3609 components. */
3610 tree
3612 {
3613 tree p;
3618 {
3622 {
3625 /* Rewrite complex type with component type. */
3629 /* Add another component type for the imaginary part. */
3634 /* Skip the newly created node. */
3636 }
3637 }
3640 }
3641 \f
3642 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3643 The RETVAL parameter specifies whether return value needs to be saved, other
3644 parameters are documented in the emit_library_call function below. */
3646 static rtx
3650 {
3651 /* Total size in bytes of all the stack-parms scanned so far. */
3653 /* Size of arguments before any adjustments (such as rounding). */
3656 rtx fun;
3660 CUMULATIVE_ARGS args_so_far;
3661 struct arg
3662 {
3663 rtx value;
3665 rtx reg;
3668 rtx save_area;
3669 };
3674 rtx valreg;
3680 rtx before_call;
3683 #ifdef REG_PARM_STACK_SPACE
3684 /* Define the boundary of the register parm stack space that needs to be
3685 save, if any. */
3688 #endif
3690 /* Size of the stack reserved for parameter registers. */
3696 #ifdef REG_PARM_STACK_SPACE
3697 #ifdef MAYBE_REG_PARM_STACK_SPACE
3699 #else
3701 #endif
3702 #endif
3704 /* By default, library functions can not throw. */
3708 {
3735 }
3738 /* Ensure current function's preferred stack boundary is at least
3739 what we need. */
3743 /* If this kind of value comes back in memory,
3744 decide where in memory it should come back. */
3746 {
3749 {
3750 #ifdef PCC_STATIC_STRUCT_RETURN
3751 rtx pointer_reg
3761 else
3763 #endif
3764 /* This call returns a big structure. */
3766 }
3767 }
3768 else
3771 /* ??? Unfinished: must pass the memory address as an argument. */
3773 /* Copy all the libcall-arguments out of the varargs data
3774 and into a vector ARGVEC.
3776 Compute how to pass each argument. We only support a very small subset
3777 of the full argument passing conventions to limit complexity here since
3778 library functions shouldn't have many args. */
3783 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3785 #else
3787 #endif
3794 /* Now we are about to start emitting insns that can be deleted
3795 if a libcall is deleted. */
3801 /* If there's a structure value address to be passed,
3802 either pass it in the special place, or pass it as an extra argument. */
3804 {
3806 nargs++;
3808 /* Make sure it is a reasonable operand for a move or push insn. */
3818 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3821 #endif
3824 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3826 #else
3828 #endif
3837 count++;
3838 }
3841 {
3845 /* We cannot convert the arg value to the mode the library wants here;
3846 must do it earlier where we know the signedness of the arg. */
3851 /* There's no need to call protect_from_queue, because
3852 either emit_move_insn or emit_push_insn will do that. */
3854 /* Make sure it is a reasonable operand for a move or push insn. */
3859 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
3861 {
3862 rtx slot;
3864 #ifdef FUNCTION_ARG_CALLEE_COPIES
3867 #endif
3868 ;
3870 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3871 functions, so we have to pretend this isn't such a function. */
3873 {
3877 }
3880 /* If this was a CONST function, it is now PURE since
3881 it now reads memory. */
3883 {
3886 }
3891 {
3895 }
3896 else
3897 {
3900 slot
3906 }
3910 call_fusage);
3914 slot),
3915 call_fusage);
3919 }
3920 #endif
3927 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3930 #else
3932 #endif
3935 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3937 #else
3939 #endif
3951 }
3953 #ifdef FINAL_REG_PARM_STACK_SPACE
3956 #endif
3957 /* If this machine requires an external definition for library
3958 functions, write one out. */
3963 + stack_pointer_delta
3965 / STACK_BYTES
3970 reg_parm_stack_space);
3972 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3974 #endif
3980 {
3981 /* Since the stack pointer will never be pushed, it is possible for
3982 the evaluation of a parm to clobber something we have already
3983 written to the stack. Since most function calls on RISC machines
3984 do not use the stack, this is uncommon, but must work correctly.
3986 Therefore, we save any area of the stack that was already written
3987 and that we are using. Here we set up to do this by making a new
3988 stack usage map from the old one.
3990 Another approach might be to try to reorder the argument
3991 evaluations to avoid this conflicting stack usage. */
3995 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3996 /* Since we will be writing into the entire argument area, the
3997 map must be allocated for its entire size, not just the part that
3998 is the responsibility of the caller. */
4000 #endif
4002 #ifdef ARGS_GROW_DOWNWARD
4005 #else
4007 needed);
4008 #endif
4013 initial_highest_arg_in_use);
4020 /* We must be careful to use virtual regs before they're instantiated,
4021 and real regs afterwards. Loop optimization, for example, can create
4022 new libcalls after we've instantiated the virtual regs, and if we
4023 use virtuals anyway, they won't match the rtl patterns. */
4027 else
4029 }
4030 else
4031 {
4034 }
4036 /* If we push args individually in reverse order, perform stack alignment
4037 before the first push (the last arg). */
4043 {
4046 }
4047 else
4048 {
4051 }
4053 #ifdef REG_PARM_STACK_SPACE
4055 {
4056 /* The argument list is the property of the called routine and it
4057 may clobber it. If the fixed area has been used for previous
4058 parameters, we must save and restore it. */
4061 }
4062 #endif
4064 /* Push the args that need to be pushed. */
4066 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4067 are to be pushed. */
4069 {
4077 {
4079 {
4080 /* If this is being stored into a pre-allocated, fixed-size,
4081 stack area, save any previous data at that location. */
4083 #ifdef ARGS_GROW_DOWNWARD
4084 /* stack_slot is negative, but we want to index stack_usage_map
4085 with positive values. */
4088 #else
4091 #endif
4094 /* Don't worry about things in the fixed argument area;
4095 it has already been saved. */
4099 i++;
4102 {
4103 /* We need to make a save area. */
4104 unsigned int size
4106 enum machine_mode save_mode
4108 rtx adr
4111 rtx stack_area
4115 {
4122 stack_area,
4124 BLOCK_OP_CALL_PARM);
4125 }
4126 else
4127 {
4131 }
4132 }
4133 }
4138 reg_parm_stack_space,
4141 /* Now mark the segment we just used. */
4146 NO_DEFER_POP;
4147 }
4148 }
4150 /* If we pushed args in forward order, perform stack alignment
4151 after pushing the last arg. */
4158 else
4163 /* Now load any reg parms into their regs. */
4165 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4166 are to be pushed. */
4168 {
4173 /* Handle calls that pass values in multiple non-contiguous
4174 locations. The PA64 has examples of this for library calls. */
4180 NO_DEFER_POP;
4181 }
4183 /* Any regs containing parms remain in use through the call. */
4185 {
4191 }
4193 /* Pass the function the address in which to return a structure value. */
4195 {
4199 NULL_RTX)));
4202 }
4204 /* Don't allow popping to be deferred, since then
4205 cse'ing of library calls could delete a call and leave the pop. */
4206 NO_DEFER_POP;
4210 /* Stack must be properly aligned now. */
4216 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4217 will set inhibit_defer_pop to that value. */
4218 /* The return type is needed to decide how many bytes the function pops.
4219 Signedness plays no role in that, so for simplicity, we pretend it's
4220 always signed. We also assume that the list of arguments passed has
4221 no impact, so we pretend it is unknown. */
4227 struct_value_size,
4229 valreg,
4232 /* For calls to `setjmp', etc., inform flow.c it should complain
4233 if nonvolatile values are live. For functions that cannot return,
4234 inform flow that control does not fall through. */
4237 {
4238 /* The barrier note must be emitted
4239 immediately after the CALL_INSN. Some ports emit more than
4240 just a CALL_INSN above, so we must search for it here. */
4244 {
4246 /* There was no CALL_INSN? */
4249 }
4252 }
4254 /* Now restore inhibit_defer_pop to its actual original value. */
4255 OK_DEFER_POP;
4257 /* If call is cse'able, make appropriate pair of reg-notes around it.
4258 Test valreg so we don't crash; may safely ignore `const'
4259 if return type is void. Disable for PARALLEL return values, because
4260 we have no way to move such values into a pseudo register. */
4262 {
4263 rtx insns;
4266 {
4270 }
4271 else
4272 {
4274 rtx temp;
4278 {
4283 }
4287 /* Construct an "equal form" for the value which mentions all the
4288 arguments in order as well as the function name. */
4301 note);
4306 }
4307 }
4310 /* Copy the value to the right place. */
4312 {
4314 {
4319 }
4321 {
4325 }
4328 else
4330 }
4333 {
4334 #ifdef REG_PARM_STACK_SPACE
4338 #endif
4340 /* If we saved any argument areas, restore them. */
4343 {
4354 BLOCK_OP_CALL_PARM);
4355 else
4357 }
4361 }
4365 }
4366 \f
4367 /* Output a library call to function FUN (a SYMBOL_REF rtx)
4368 (emitting the queue unless NO_QUEUE is nonzero),
4369 for a value of mode OUTMODE,
4370 with NARGS different arguments, passed as alternating rtx values
4371 and machine_modes to convert them to.
4372 The rtx values should have been passed through protect_from_queue already.
4374 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
4375 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
4376 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
4377 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
4378 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
4379 or other LCT_ value for other types of library calls. */
4381 void
4384 {
4390 }
4391 \f
4392 /* Like emit_library_call except that an extra argument, VALUE,
4393 comes second and says where to store the result.
4394 (If VALUE is zero, this function chooses a convenient way
4395 to return the value.
4397 This function returns an rtx for where the value is to be found.
4398 If VALUE is nonzero, VALUE is returned. */
4400 rtx
4404 {
4405 rtx result;
4414 }
4415 \f
4416 /* Store a single argument for a function call
4417 into the register or memory area where it must be passed.
4418 *ARG describes the argument value and where to pass it.
4420 ARGBLOCK is the address of the stack-block for all the arguments,
4421 or 0 on a machine where arguments are pushed individually.
4423 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4424 so must be careful about how the stack is used.
4426 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4427 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4428 that we need not worry about saving and restoring the stack.
4430 FNDECL is the declaration of the function we are calling.
4432 Return nonzero if this arg should cause sibcall failure,
4433 zero otherwise. */
4435 static int
4438 {
4449 /* Push a new temporary level for any temporaries we make for
4450 this argument. */
4454 {
4455 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4456 save any previous data at that location. */
4458 {
4459 #ifdef ARGS_GROW_DOWNWARD
4460 /* stack_slot is negative, but we want to index stack_usage_map
4461 with positive values. */
4464 else
4468 #else
4471 else
4475 #endif
4478 /* Don't worry about things in the fixed argument area;
4479 it has already been saved. */
4483 i++;
4486 {
4487 /* We need to make a save area. */
4494 {
4503 BLOCK_OP_CALL_PARM);
4504 }
4505 else
4506 {
4509 }
4510 }
4511 }
4512 }
4514 /* If this isn't going to be placed on both the stack and in registers,
4515 set up the register and number of words. */
4517 {
4520 else
4523 }
4526 /* Being passed entirely in a register. We shouldn't be called in
4527 this case. */
4530 /* If this arg needs special alignment, don't load the registers
4531 here. */
4535 /* If this is being passed partially in a register, we can't evaluate
4536 it directly into its stack slot. Otherwise, we can. */
4538 {
4539 /* stack_arg_under_construction is nonzero if a function argument is
4540 being evaluated directly into the outgoing argument list and
4541 expand_call must take special action to preserve the argument list
4542 if it is called recursively.
4544 For scalar function arguments stack_usage_map is sufficient to
4545 determine which stack slots must be saved and restored. Scalar
4546 arguments in general have pass_on_stack == 0.
4548 If this argument is initialized by a function which takes the
4549 address of the argument (a C++ constructor or a C function
4550 returning a BLKmode structure), then stack_usage_map is
4551 insufficient and expand_call must push the stack around the
4552 function call. Such arguments have pass_on_stack == 1.
4554 Note that it is always safe to set stack_arg_under_construction,
4555 but this generates suboptimal code if set when not needed. */
4558 stack_arg_under_construction++;
4561 (partial
4566 /* If we are promoting object (or for any other reason) the mode
4567 doesn't agree, convert the mode. */
4574 stack_arg_under_construction--;
4575 }
4577 /* Don't allow anything left on stack from computation
4578 of argument to alloca. */
4583 /* If the value is already in the stack slot, we are done. */
4584 ;
4586 {
4589 /* Argument is a scalar, not entirely passed in registers.
4590 (If part is passed in registers, arg->partial says how much
4591 and emit_push_insn will take care of putting it there.)
4593 Push it, and if its size is less than the
4594 amount of space allocated to it,
4595 also bump stack pointer by the additional space.
4596 Note that in C the default argument promotions
4597 will prevent such mismatches. */
4600 /* Compute how much space the push instruction will push.
4601 On many machines, pushing a byte will advance the stack
4602 pointer by a halfword. */
4603 #ifdef PUSH_ROUNDING
4605 #endif
4608 /* Compute how much space the argument should get:
4609 round up to a multiple of the alignment for arguments. */
4615 /* This isn't already where we want it on the stack, so put it there.
4616 This can either be done with push or copy insns. */
4622 /* Unless this is a partially-in-register argument, the argument is now
4623 in the stack. */
4626 }
4627 else
4628 {
4629 /* BLKmode, at least partly to be pushed. */
4633 rtx size_rtx;
4635 /* Pushing a nonscalar.
4636 If part is passed in registers, PARTIAL says how much
4637 and emit_push_insn will take care of putting it there. */
4639 /* Round its size up to a multiple
4640 of the allocation unit for arguments. */
4643 {
4646 }
4647 else
4648 {
4649 /* PUSH_ROUNDING has no effect on us, because
4650 emit_push_insn for BLKmode is careful to avoid it. */
4652 {
4653 /* Use the size of the elt to compute excess. */
4658 }
4659 else
4665 }
4667 /* Some types will require stricter alignment, which will be
4668 provided for elsewhere in argument layout. */
4671 /* When an argument is padded down, the block is aligned to
4672 PARM_BOUNDARY, but the actual argument isn't. */
4674 {
4678 {
4681 }
4682 }
4685 {
4686 /* emit_push_insn might not work properly if arg->value and
4687 argblock + arg->locate.offset areas overlap. */
4694 current_function_internal_arg_pointer
4696 {
4700 /* expand_call should ensure this. */
4705 {
4708 }
4710 {
4713 }
4714 }
4715 }
4722 /* Unless this is a partially-in-register argument, the argument is now
4723 in the stack.
4725 ??? Unlike the case above, in which we want the actual
4726 address of the data, so that we can load it directly into a
4727 register, here we want the address of the stack slot, so that
4728 it's properly aligned for word-by-word copying or something
4729 like that. It's not clear that this is always correct. */
4732 }
4734 /* Mark all slots this store used. */
4740 /* Once we have pushed something, pops can't safely
4741 be deferred during the rest of the arguments. */
4742 NO_DEFER_POP;
4744 /* ANSI doesn't require a sequence point here,
4745 but PCC has one, so this will avoid some problems. */
4748 /* Free any temporary slots made in processing this argument. Show
4749 that we might have taken the address of something and pushed that
4750 as an operand. */
4756 }
4758 /* Nonzero if we do not know how to pass TYPE solely in registers.
4759 We cannot do so in the following cases:
4761 - if the type has variable size
4762 - if the type is marked as addressable (it is required to be constructed
4763 into the stack)
4764 - if the padding and mode of the type is such that a copy into a register
4765 would put it into the wrong part of the register.
4767 Which padding can't be supported depends on the byte endianness.
4769 A value in a register is implicitly padded at the most significant end.
4770 On a big-endian machine, that is the lower end in memory.
4771 So a value padded in memory at the upper end can't go in a register.
4772 For a little-endian machine, the reverse is true. */
4774 bool
4776 {
4780 /* If the type has variable size... */
4784 /* If the type is marked as addressable (it is required
4785 to be constructed into the stack)... */
4789 /* If the padding and mode of the type is such that a copy into
4790 a register would put it into the wrong part of the register. */
4798 }