| blob | b4d66f9221286c725b0a7e0ebda8291c6d2c731e |
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 *);
153 #ifdef REG_PARM_STACK_SPACE
156 #endif
157 \f
158 /* If WHICH is 1, return 1 if EXP contains a call to the built-in function
159 `alloca'.
161 If WHICH is 0, return 1 if EXP contains a call to any function.
162 Actually, we only need return 1 if evaluating EXP would require pushing
163 arguments on the stack, but that is too difficult to compute, so we just
164 assume any function call might require the stack. */
168 static int
170 {
177 }
179 /* Recursive function to do the work of above function. */
181 static int
183 {
189 /* If this code is language-specific, we don't know what it will do. */
194 {
200 && (TYPE_RETURNS_STACK_DEPRESSED
214 {
215 tree tem;
220 }
230 calls_function_save_exprs);
235 {
236 tree local;
237 tree subblock;
245 subblock;
249 }
260 }
262 /* Only expressions and blocks can contain calls. */
272 }
273 \f
274 /* Force FUNEXP into a form suitable for the address of a CALL,
275 and return that as an rtx. Also load the static chain register
276 if FNDECL is a nested function.
278 CALL_FUSAGE points to a variable holding the prospective
279 CALL_INSN_FUNCTION_USAGE information. */
281 rtx
284 {
290 /* Get possible static chain value for nested function in C. */
293 /* Make a valid memory address and copy constants through pseudo-regs,
294 but not for a constant address if -fno-function-cse. */
296 /* If we are using registers for parameters, force the
297 function address into a register now. */
302 {
303 #ifndef NO_FUNCTION_CSE
305 #ifdef NO_RECURSIVE_FUNCTION_CSE
307 #endif
309 #endif
310 }
313 {
318 }
321 }
323 /* Generate instructions to call function FUNEXP,
324 and optionally pop the results.
325 The CALL_INSN is the first insn generated.
327 FNDECL is the declaration node of the function. This is given to the
328 macro RETURN_POPS_ARGS to determine whether this function pops its own args.
330 FUNTYPE is the data type of the function. This is given to the macro
331 RETURN_POPS_ARGS to determine whether this function pops its own args.
332 We used to allow an identifier for library functions, but that doesn't
333 work when the return type is an aggregate type and the calling convention
334 says that the pointer to this aggregate is to be popped by the callee.
336 STACK_SIZE is the number of bytes of arguments on the stack,
337 ROUNDED_STACK_SIZE is that number rounded up to
338 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
339 both to put into the call insn and to generate explicit popping
340 code if necessary.
342 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
343 It is zero if this call doesn't want a structure value.
345 NEXT_ARG_REG is the rtx that results from executing
346 FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1)
347 just after all the args have had their registers assigned.
348 This could be whatever you like, but normally it is the first
349 arg-register beyond those used for args in this call,
350 or 0 if all the arg-registers are used in this call.
351 It is passed on to `gen_call' so you can put this info in the call insn.
353 VALREG is a hard register in which a value is returned,
354 or 0 if the call does not return a value.
356 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
357 the args to this call were processed.
358 We restore `inhibit_defer_pop' to that value.
360 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
361 denote registers used by the called function. */
363 static void
365 HOST_WIDE_INT stack_size ATTRIBUTE_UNUSED,
366 HOST_WIDE_INT rounded_stack_size,
367 HOST_WIDE_INT struct_value_size ATTRIBUTE_UNUSED,
371 {
373 rtx call_insn;
376 #if defined (HAVE_call) && defined (HAVE_call_value)
377 rtx struct_value_size_rtx;
379 #endif
381 #ifdef CALL_POPS_ARGS
383 #endif
385 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
386 and we don't want to load it into a register as an optimization,
387 because prepare_call_address already did it if it should be done. */
391 #if defined (HAVE_sibcall_pop) && defined (HAVE_sibcall_value_pop)
395 {
397 rtx pat;
399 /* If this subroutine pops its own args, record that in the call insn
400 if possible, for the sake of frame pointer elimination. */
406 n_pop);
407 else
413 }
414 else
415 #endif
417 #if defined (HAVE_call_pop) && defined (HAVE_call_value_pop)
418 /* If the target has "call" or "call_value" insns, then prefer them
419 if no arguments are actually popped. If the target does not have
420 "call" or "call_value" insns, then we must use the popping versions
421 even if the call has no arguments to pop. */
422 #if defined (HAVE_call) && defined (HAVE_call_value)
425 #else
427 #endif
428 {
430 rtx pat;
432 /* If this subroutine pops its own args, record that in the call insn
433 if possible, for the sake of frame pointer elimination. */
439 else
445 }
446 else
447 #endif
449 #if defined (HAVE_sibcall) && defined (HAVE_sibcall_value)
452 {
456 rounded_stack_size_rtx,
458 else
461 struct_value_size_rtx));
462 }
463 else
464 #endif
466 #if defined (HAVE_call) && defined (HAVE_call_value)
468 {
473 NULL_RTX));
474 else
477 struct_value_size_rtx));
478 }
479 else
480 #endif
483 /* Find the call we just emitted. */
486 /* Mark memory as used for "pure" function call. */
488 call_fusage
489 = gen_rtx_EXPR_LIST
493 call_fusage);
495 /* Put the register usage information there. */
498 /* If this is a const call, then set the insn's unchanging bit. */
502 /* If this call can't throw, attach a REG_EH_REGION reg note to that
503 effect. */
507 else
518 {
522 }
526 /* Restore this now, so that we do defer pops for this call's args
527 if the context of the call as a whole permits. */
531 {
540 }
543 {
544 /* If returning from the subroutine does not automatically pop the args,
545 we need an instruction to pop them sooner or later.
546 Perhaps do it now; perhaps just record how much space to pop later.
548 If returning from the subroutine does pop the args, indicate that the
549 stack pointer will be changed. */
552 {
554 /* Just pretend we did the pop. */
559 else
561 }
562 }
563 /* When we accumulate outgoing args, we must avoid any stack manipulations.
564 Restore the stack pointer to its original value now. Usually
565 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
566 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
567 popping variants of functions exist as well.
569 ??? We may optimize similar to defer_pop above, but it is
570 probably not worthwhile.
572 ??? It will be worthwhile to enable combine_stack_adjustments even for
573 such machines. */
576 }
578 /* Determine if the function identified by NAME and FNDECL is one with
579 special properties we wish to know about.
581 For example, if the function might return more than one time (setjmp), then
582 set RETURNS_TWICE to a nonzero value.
584 Similarly set LONGJMP for if the function is in the longjmp family.
586 Set MAY_BE_ALLOCA for any memory allocation function that might allocate
587 space from the stack such as alloca. */
589 static int
591 {
595 /* Exclude functions not at the file scope, or not `extern',
596 since they are not the magic functions we would otherwise
597 think they are.
598 FIXME: this should be handled with attributes, not with this
599 hacky imitation of DECL_ASSEMBLER_NAME. It's (also) wrong
600 because you can declare fork() inside a function if you
601 wish. */
605 {
609 /* We assume that alloca will always be called by name. It
610 makes no sense to pass it as a pointer-to-function to
611 anything that does not understand its behavior. */
620 /* Disregard prefix _, __ or __x. */
622 {
627 else
629 }
632 {
645 }
658 /* Linux specific: __clone. check NAME to insist on the
659 leading underscores, to avoid polluting the ISO / POSIX
660 namespace. */
669 }
671 }
673 /* Return nonzero when tree represent call to longjmp. */
675 int
677 {
679 }
681 /* Return true when exp contains alloca call. */
682 bool
684 {
693 }
695 /* Detect flags (function attributes) from the function decl or type node. */
697 int
699 {
704 {
709 {
714 }
716 /* The function exp may have the `malloc' attribute. */
720 /* The function exp may have the `pure' attribute. */
729 }
737 /* Mark if the function returns with the stack pointer depressed. We
738 cannot consider it pure or constant in that case. */
740 {
743 }
746 }
748 /* Detect flags from a CALL_EXPR. */
750 int
752 {
758 else
759 {
763 else
765 }
768 }
770 /* Precompute all register parameters as described by ARGS, storing values
771 into fields within the ARGS array.
773 NUM_ACTUALS indicates the total number elements in the ARGS array.
775 Set REG_PARM_SEEN if we encounter a register parameter. */
777 static void
779 {
786 {
790 {
797 /* ANSI doesn't require a sequence point here,
798 but PCC has one, so this will avoid some problems. */
800 }
802 /* If the value is a non-legitimate constant, force it into a
803 pseudo now. TLS symbols sometimes need a call to resolve. */
808 /* If we are to promote the function arg to a wider mode,
809 do it now. */
817 /* If the value is expensive, and we are inside an appropriately
818 short loop, put the value into a pseudo and then put the pseudo
819 into the hard reg.
821 For small register classes, also do this if this call uses
822 register parameters. This is to avoid reload conflicts while
823 loading the parameters registers. */
833 }
834 }
836 #ifdef REG_PARM_STACK_SPACE
838 /* The argument list is the property of the called routine and it
839 may clobber it. If the fixed area has been used for previous
840 parameters, we must save and restore it. */
842 static rtx
843 save_fixed_argument_area (int reg_parm_stack_space, rtx argblock, int *low_to_save, int *high_to_save)
844 {
848 /* Compute the boundary of the area that needs to be saved, if any. */
850 #ifdef ARGS_GROW_DOWNWARD
852 #endif
858 {
862 rtx stack_area;
863 rtx save_area;
866 ;
874 /* If we don't have the required alignment, must do this
875 in BLKmode. */
880 #ifdef ARGS_GROW_DOWNWARD
882 #else
884 #endif
888 delta)));
892 {
896 }
897 else
898 {
901 }
904 }
907 }
909 static void
911 {
914 rtx stack_area;
916 #ifdef ARGS_GROW_DOWNWARD
918 #else
920 #endif
928 else
931 BLOCK_OP_CALL_PARM);
932 }
935 /* If any elements in ARGS refer to parameters that are to be passed in
936 registers, but not in memory, and whose alignment does not permit a
937 direct copy into registers. Copy the values into a group of pseudos
938 which we will later copy into the appropriate hard registers.
940 Pseudos for each unaligned argument will be stored into the array
941 args[argnum].aligned_regs. The caller is responsible for deallocating
942 the aligned_regs array if it is nonzero. */
944 static void
946 {
954 {
962 /* Structures smaller than a word are normally aligned to the
963 least significant byte. On a BYTES_BIG_ENDIAN machine,
964 this means we must skip the empty high order bytes when
965 calculating the bit offset. */
967 #ifdef BLOCK_REG_PADDING
971 #else
972 && BYTES_BIG_ENDIAN
973 #endif
974 )
978 {
987 /* There is no need to restrict this code to loading items
988 in TYPE_ALIGN sized hunks. The bitfield instructions can
989 load up entire word sized registers efficiently.
991 ??? This may not be needed anymore.
992 We use to emit a clobber here but that doesn't let later
993 passes optimize the instructions we emit. By storing 0 into
994 the register later passes know the first AND to zero out the
995 bitfield being set in the register is unnecessary. The store
996 of 0 will be deleted as will at least the first AND. */
1003 }
1004 }
1005 }
1007 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
1008 ACTPARMS.
1010 NUM_ACTUALS is the total number of parameters.
1012 N_NAMED_ARGS is the total number of named arguments.
1014 FNDECL is the tree code for the target of this call (if known)
1016 ARGS_SO_FAR holds state needed by the target to know where to place
1017 the next argument.
1019 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
1020 for arguments which are passed in registers.
1022 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
1023 and may be modified by this routine.
1025 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
1026 flags which may may be modified by this routine. */
1028 static void
1038 {
1039 /* 1 if scanning parms front to back, -1 if scanning back to front. */
1042 /* Count arg position in order args appear. */
1046 tree p;
1051 /* In this loop, we consider args in the order they are written.
1052 We fill up ARGS from the front or from the back if necessary
1053 so that in any case the first arg to be pushed ends up at the front. */
1056 {
1058 /* In this case, must reverse order of args
1059 so that we compute and push the last arg first. */
1060 }
1061 else
1062 {
1064 }
1066 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1068 {
1075 /* Replace erroneous argument with constant zero. */
1079 /* If TYPE is a transparent union, pass things the way we would
1080 pass the first field of the union. We have already verified that
1081 the modes are the same. */
1085 /* Decide where to pass this arg.
1087 args[i].reg is nonzero if all or part is passed in registers.
1089 args[i].partial is nonzero if part but not all is passed in registers,
1090 and the exact value says how many words are passed in registers.
1092 args[i].pass_on_stack is nonzero if the argument must at least be
1093 computed on the stack. It may then be loaded back into registers
1094 if args[i].reg is nonzero.
1096 These decisions are driven by the FUNCTION_... macros and must agree
1097 with those made by function.c. */
1099 /* See if this argument should be passed by invisible reference. */
1102 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
1105 #endif
1106 )
1107 {
1108 /* If we're compiling a thunk, pass through invisible
1109 references instead of making a copy. */
1111 #ifdef FUNCTION_ARG_CALLEE_COPIES
1114 /* If it's in a register, we must make a copy of it too. */
1115 /* ??? Is this a sufficient test? Is there a better one? */
1119 #endif
1120 )
1121 {
1122 /* C++ uses a TARGET_EXPR to indicate that we want to make a
1123 new object from the argument. If we are passing by
1124 invisible reference, the callee will do that for us, so we
1125 can strip off the TARGET_EXPR. This is not always safe,
1126 but it is safe in the only case where this is a useful
1127 optimization; namely, when the argument is a plain object.
1128 In that case, the frontend is just asking the backend to
1129 make a bitwise copy of the argument. */
1140 }
1142 {
1143 /* In the V3 C++ ABI, parameters are destroyed in the caller.
1144 We implement this by passing the address of the temporary
1145 rather than expanding it into another allocated slot. */
1150 }
1151 else
1152 {
1153 /* We make a copy of the object and pass the address to the
1154 function being called. */
1155 rtx copy;
1161 STACK_CHECK_MAX_VAR_SIZE))))
1162 {
1163 /* This is a variable-sized object. Make space on the stack
1164 for it. */
1168 {
1172 }
1175 allocate_dynamic_stack_space
1178 }
1179 else
1189 }
1190 }
1203 #ifdef FUNCTION_INCOMING_ARG
1204 /* If this is a sibling call and the machine has register windows, the
1205 register window has to be unwinded before calling the routine, so
1206 arguments have to go into the incoming registers. */
1209 #else
1211 #endif
1213 #ifdef FUNCTION_ARG_PARTIAL_NREGS
1218 #endif
1222 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1223 it means that we are to pass this arg in the register(s) designated
1224 by the PARALLEL, but also to pass it in the stack. */
1229 /* If this is an addressable type, we must preallocate the stack
1230 since we must evaluate the object into its final location.
1232 If this is to be passed in both registers and the stack, it is simpler
1233 to preallocate. */
1238 /* If this is an addressable type, we cannot pre-evaluate it. Thus,
1239 we cannot consider this function call constant. */
1243 /* Compute the stack-size of this argument. */
1248 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1250 #else
1252 #endif
1255 #ifdef BLOCK_REG_PADDING
1256 else
1257 /* The argument is passed entirely in registers. See at which
1258 end it should be padded. */
1262 #endif
1264 /* Update ARGS_SIZE, the total stack space for args so far. */
1270 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1271 have been used, etc. */
1275 }
1276 }
1278 /* Update ARGS_SIZE to contain the total size for the argument block.
1279 Return the original constant component of the argument block's size.
1281 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1282 for arguments passed in registers. */
1284 static int
1288 {
1291 /* For accumulate outgoing args mode we don't need to align, since the frame
1292 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1293 backends from generating misaligned frame sizes. */
1297 /* Compute the actual size of the argument block required. The variable
1298 and constant sizes must be combined, the size may have to be rounded,
1299 and there may be a minimum required size. */
1302 {
1308 {
1309 /* We don't handle this case yet. To handle it correctly we have
1310 to add the delta, round and subtract the delta.
1311 Currently no machine description requires this support. */
1315 }
1318 {
1319 args_size->var
1323 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1324 /* The area corresponding to register parameters is not to count in
1325 the size of the block we need. So make the adjustment. */
1326 args_size->var
1329 #endif
1330 }
1331 }
1332 else
1333 {
1338 + stack_pointer_delta
1340 / preferred_stack_boundary
1345 reg_parm_stack_space);
1347 #ifdef MAYBE_REG_PARM_STACK_SPACE
1350 #endif
1352 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1354 #endif
1355 }
1357 }
1359 /* Precompute parameters as needed for a function call.
1361 FLAGS is mask of ECF_* constants.
1363 NUM_ACTUALS is the number of arguments.
1365 ARGS is an array containing information for each argument; this
1366 routine fills in the INITIAL_VALUE and VALUE fields for each
1367 precomputed argument. */
1369 static void
1371 {
1374 /* If this function call is cse'able, precompute all the parameters.
1375 Note that if the parameter is constructed into a temporary, this will
1376 cause an additional copy because the parameter will be constructed
1377 into a temporary location and then copied into the outgoing arguments.
1378 If a parameter contains a call to alloca and this function uses the
1379 stack, precompute the parameter. */
1381 /* If we preallocated the stack space, and some arguments must be passed
1382 on the stack, then we must precompute any parameter which contains a
1383 function call which will store arguments on the stack.
1384 Otherwise, evaluating the parameter may clobber previous parameters
1385 which have already been stored into the stack. (we have code to avoid
1386 such case by saving the outgoing stack arguments, but it results in
1387 worse code) */
1392 {
1395 /* If this is an addressable type, we cannot pre-evaluate it. */
1402 /* ANSI doesn't require a sequence point here,
1403 but PCC has one, so this will avoid some problems. */
1411 {
1415 #ifdef PROMOTE_FOR_CALL_ONLY
1416 /* CSE will replace this only if it contains args[i].value
1417 pseudo, so convert it down to the declared mode using
1418 a SUBREG. */
1421 {
1427 }
1428 #endif
1429 }
1430 }
1431 }
1433 /* Given the current state of MUST_PREALLOCATE and information about
1434 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1435 compute and return the final value for MUST_PREALLOCATE. */
1437 static int
1438 finalize_must_preallocate (int must_preallocate, int num_actuals, struct arg_data *args, struct args_size *args_size)
1439 {
1440 /* See if we have or want to preallocate stack space.
1442 If we would have to push a partially-in-regs parm
1443 before other stack parms, preallocate stack space instead.
1445 If the size of some parm is not a multiple of the required stack
1446 alignment, we must preallocate.
1448 If the total size of arguments that would otherwise create a copy in
1449 a temporary (such as a CALL) is more than half the total argument list
1450 size, preallocation is faster.
1452 Another reason to preallocate is if we have a machine (like the m88k)
1453 where stack alignment is required to be maintained between every
1454 pair of insns, not just when the call is made. However, we assume here
1455 that such machines either do not have push insns (and hence preallocation
1456 would occur anyway) or the problem is taken care of with
1457 PUSH_ROUNDING. */
1460 {
1466 {
1477 copy_to_evaluate_size
1479 }
1484 }
1486 }
1488 /* If we preallocated stack space, compute the address of each argument
1489 and store it into the ARGS array.
1491 We need not ensure it is a valid memory address here; it will be
1492 validized when it is used.
1494 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1496 static void
1498 {
1500 {
1508 {
1511 rtx addr;
1513 /* Skip this parm if it will not be passed on the stack. */
1519 else
1530 else
1539 /* Function incoming arguments may overlap with sibling call
1540 outgoing arguments and we cannot allow reordering of reads
1541 from function arguments with stores to outgoing arguments
1542 of sibling calls. */
1545 }
1546 }
1547 }
1549 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1550 in a call instruction.
1552 FNDECL is the tree node for the target function. For an indirect call
1553 FNDECL will be NULL_TREE.
1555 ADDR is the operand 0 of CALL_EXPR for this call. */
1557 static rtx
1559 {
1560 rtx funexp;
1562 /* Get the function to call, in the form of RTL. */
1564 {
1565 /* If this is the first use of the function, see if we need to
1566 make an external definition for it. */
1568 {
1571 }
1573 /* Get a SYMBOL_REF rtx for the function address. */
1575 }
1576 else
1577 /* Generate an rtx (probably a pseudo-register) for the address. */
1578 {
1583 }
1585 }
1587 /* Do the register loads required for any wholly-register parms or any
1588 parms which are passed both on the stack and in a register. Their
1589 expressions were already evaluated.
1591 Mark all register-parms as living through the call, putting these USE
1592 insns in the CALL_INSN_FUNCTION_USAGE field.
1594 When IS_SIBCALL, perform the check_sibcall_overlap_argument_overlap
1595 checking, setting *SIBCALL_FAILURE if appropriate. */
1597 static void
1601 {
1605 {
1609 {
1614 /* Set to non-negative if must move a word at a time, even if just
1615 one word (e.g, partial == 1 && mode == DFmode). Set to -1 if
1616 we just use a normal move insn. This value can be zero if the
1617 argument is a zero size structure with no fields. */
1622 {
1625 }
1626 else
1629 /* Handle calls that pass values in multiple non-contiguous
1630 locations. The Irix 6 ABI has examples of this. */
1633 {
1637 }
1639 /* If simple case, just do move. If normal partial, store_one_arg
1640 has already loaded the register for us. In all other cases,
1641 load the register(s) from memory. */
1644 {
1646 #ifdef BLOCK_REG_PADDING
1647 /* Handle case where we have a value that needs shifting
1648 up to the msb. eg. a QImode value and we're padding
1649 upward on a BYTES_BIG_ENDIAN machine. */
1653 {
1654 rtx x;
1657 /* Assigning REG here rather than a temp makes CALL_FUSAGE
1658 report the whole reg as used. Strictly speaking, the
1659 call only uses SIZE bytes at the msb end, but it doesn't
1660 seem worth generating rtl to say that. */
1666 }
1667 #endif
1668 }
1670 /* If we have pre-computed the values to put in the registers in
1671 the case of non-aligned structures, copy them in now. */
1679 {
1682 #ifdef BLOCK_REG_PADDING
1683 /* Handle a BLKmode that needs shifting. */
1686 {
1698 }
1699 else
1700 #endif
1702 }
1704 /* When a parameter is a block, and perhaps in other cases, it is
1705 possible that it did a load from an argument slot that was
1706 already clobbered. */
1711 /* Handle calls that pass values in multiple non-contiguous
1712 locations. The Irix 6 ABI has examples of this. */
1717 else
1719 }
1720 }
1721 }
1723 /* Try to integrate function. See expand_inline_function for documentation
1724 about the parameters. */
1726 static rtx
1729 {
1730 rtx temp;
1731 rtx before_call;
1736 #ifdef REG_PARM_STACK_SPACE
1737 #ifdef MAYBE_REG_PARM_STACK_SPACE
1739 #else
1741 #endif
1742 #endif
1750 structure_value_addr);
1754 /* If inlining succeeded, return. */
1756 {
1758 {
1759 /* If the outgoing argument list must be preserved, push
1760 the stack before executing the inlined function if it
1761 makes any calls. */
1767 ;
1770 {
1771 rtx first_insn
1775 /* Look for a call in the inline function code.
1776 If DECL_SAVED_INSNS (fndecl)->outgoing_args_size is
1777 nonzero then there is a call and it is not necessary
1778 to scan the insns. */
1786 {
1787 /* Reserve enough stack space so that the largest
1788 argument list of any function call in the inline
1789 function does not overlap the argument list being
1790 evaluated. This is usually an overestimate because
1791 allocate_dynamic_stack_space reserves space for an
1792 outgoing argument list in addition to the requested
1793 space, but there is no way to ask for stack space such
1794 that an argument list of a certain length can be
1795 safely constructed.
1797 Add the stack space reserved for register arguments, if
1798 any, in the inline function. What is really needed is the
1799 largest value of reg_parm_stack_space in the inline
1800 function, but that is not available. Using the current
1801 value of reg_parm_stack_space is wrong, but gives
1802 correct results on all supported machines. */
1815 }
1816 }
1817 }
1819 /* If the result is equivalent to TARGET, return TARGET to simplify
1820 checks in store_expr. They can be equivalent but not equal in the
1821 case of a function that returns BLKmode. */
1825 }
1827 /* If inlining failed, mark FNDECL as needing to be compiled
1828 separately after all. If function was declared inline,
1829 give a warning. */
1832 {
1835 }
1838 }
1840 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
1841 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
1842 bytes, then we would need to push some additional bytes to pad the
1843 arguments. So, we compute an adjust to the stack pointer for an
1844 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
1845 bytes. Then, when the arguments are pushed the stack will be perfectly
1846 aligned. ARGS_SIZE->CONSTANT is set to the number of bytes that should
1847 be popped after the call. Returns the adjustment. */
1849 static int
1853 {
1854 /* The number of bytes to pop so that the stack will be
1855 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
1856 HOST_WIDE_INT adjustment;
1857 /* The alignment of the stack after the arguments are pushed, if we
1858 just pushed the arguments without adjust the stack here. */
1859 HOST_WIDE_INT unadjusted_alignment;
1861 unadjusted_alignment
1865 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
1866 as possible -- leaving just enough left to cancel out the
1867 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
1868 PENDING_STACK_ADJUST is non-negative, and congruent to
1869 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
1871 /* Begin by trying to pop all the bytes. */
1872 unadjusted_alignment
1873 = (unadjusted_alignment
1876 /* Push enough additional bytes that the stack will be aligned
1877 after the arguments are pushed. */
1879 {
1882 else
1884 }
1886 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
1887 bytes after the call. The right number is the entire
1888 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
1889 by the arguments in the first place. */
1890 args_size->constant
1894 }
1896 /* Scan X expression if it does not dereference any argument slots
1897 we already clobbered by tail call arguments (as noted in stored_args_map
1898 bitmap).
1899 Return nonzero if X expression dereferences such argument slots,
1900 zero otherwise. */
1902 static int
1904 {
1905 RTX_CODE code;
1916 {
1921 current_function_internal_arg_pointer
1924 else
1927 #ifdef ARGS_GROW_DOWNWARD
1929 #endif
1937 }
1939 /* Scan all subexpressions. */
1942 {
1944 {
1947 }
1949 {
1953 }
1954 }
1956 }
1958 /* Scan sequence after INSN if it does not dereference any argument slots
1959 we already clobbered by tail call arguments (as noted in stored_args_map
1960 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
1961 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
1962 should be 0). Return nonzero if sequence after INSN dereferences such argument
1963 slots, zero otherwise. */
1965 static int
1967 {
1972 else
1981 {
1982 #ifdef ARGS_GROW_DOWNWARD
1984 #else
1986 #endif
1990 }
1992 }
1994 static tree
1996 {
1998 {
2007 {
2013 }
2018 }
2020 }
2023 /* If function value *VALUE was returned at the most significant end of a
2024 register, shift it towards the least significant end and convert it to
2025 TYPE's mode. Return true and update *VALUE if some action was needed.
2027 TYPE is the type of the function's return value, which is known not
2028 to have mode BLKmode. */
2030 static bool
2032 {
2034 {
2035 HOST_WIDE_INT shift;
2040 {
2045 }
2046 }
2048 }
2050 /* Generate all the code for a function call
2051 and return an rtx for its value.
2052 Store the value in TARGET (specified as an rtx) if convenient.
2053 If the value is stored in TARGET then TARGET is returned.
2054 If IGNORE is nonzero, then we ignore the value of the function call. */
2056 rtx
2058 {
2059 /* Nonzero if we are currently expanding a call. */
2062 /* List of actual parameters. */
2064 /* RTX for the function to be called. */
2065 rtx funexp;
2066 /* Sequence of insns to perform a tail recursive "call". */
2068 /* Sequence of insns to perform a normal "call". */
2070 /* Sequence of insns to perform a tail recursive "call". */
2072 /* Data type of the function. */
2073 tree funtype;
2074 tree type_arg_types;
2075 /* Declaration of the function being called,
2076 or 0 if the function is computed (not known by name). */
2078 rtx insn;
2083 /* Register in which non-BLKmode value will be returned,
2084 or 0 if no value or if value is BLKmode. */
2085 rtx valreg;
2086 /* Address where we should return a BLKmode value;
2087 0 if value not BLKmode. */
2089 /* Nonzero if that address is being passed by treating it as
2090 an extra, implicit first parameter. Otherwise,
2091 it is passed by being copied directly into struct_value_rtx. */
2093 /* Size of aggregate value wanted, or zero if none wanted
2094 or if we are using the non-reentrant PCC calling convention
2095 or expecting the value in registers. */
2097 /* Nonzero if called function returns an aggregate in memory PCC style,
2098 by returning the address of where to find it. */
2102 /* Number of actual parameters in this call, including struct value addr. */
2104 /* Number of named args. Args after this are anonymous ones
2105 and they must all go on the stack. */
2108 /* Vector of information about each argument.
2109 Arguments are numbered in the order they will be pushed,
2110 not the order they are written. */
2113 /* Total size in bytes of all the stack-parms scanned so far. */
2116 /* Size of arguments before any adjustments (such as rounding). */
2118 /* Data on reg parms scanned so far. */
2119 CUMULATIVE_ARGS args_so_far;
2120 /* Nonzero if a reg parm has been scanned. */
2122 /* Nonzero if this is an indirect function call. */
2124 /* Nonzero if we must avoid push-insns in the args for this call.
2125 If stack space is allocated for register parameters, but not by the
2126 caller, then it is preallocated in the fixed part of the stack frame.
2127 So the entire argument block must then be preallocated (i.e., we
2128 ignore PUSH_ROUNDING in that case). */
2132 /* Size of the stack reserved for parameter registers. */
2135 /* Address of space preallocated for stack parms
2136 (on machines that lack push insns), or 0 if space not preallocated. */
2139 /* Mask of ECF_ flags. */
2141 /* Nonzero if this is a call to an inline function. */
2143 #ifdef REG_PARM_STACK_SPACE
2144 /* Define the boundary of the register parm stack space that needs to be
2145 saved, if any. */
2148 #endif
2156 /* State variables to track stack modifications. */
2162 /* Some stack pointer alterations we make are performed via
2163 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2164 which we then also need to save/restore along the way. */
2167 rtx call_fusage;
2171 /* The alignment of the stack, in bits. */
2172 HOST_WIDE_INT preferred_stack_boundary;
2173 /* The alignment of the stack, in bytes. */
2174 HOST_WIDE_INT preferred_unit_stack_boundary;
2176 /* See if this is "nothrow" function call. */
2180 /* See if we can find a DECL-node for the actual function.
2181 As a result, decide whether this is a call to an integrable function. */
2185 {
2193 {
2194 /* In case this function later becomes inlinable,
2195 record that there was already a non-inline call to it.
2197 Use abstraction instead of setting TREE_ADDRESSABLE
2198 directly. */
2201 {
2204 }
2206 }
2215 }
2217 /* If we don't have specific function to call, see if we have a
2218 attributes set in the type. */
2219 else
2220 {
2227 }
2231 /* Warn if this value is an aggregate type,
2232 regardless of which calling convention we are using for it. */
2236 /* If the result of a pure or const function call is ignored (or void),
2237 and none of its arguments are volatile, we can avoid expanding the
2238 call and just evaluate the arguments for side-effects. */
2242 {
2244 tree arg;
2248 {
2251 }
2254 {
2259 }
2260 }
2262 #ifdef REG_PARM_STACK_SPACE
2263 #ifdef MAYBE_REG_PARM_STACK_SPACE
2265 #else
2267 #endif
2268 #endif
2270 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2273 #endif
2275 /* Set up a place to return a structure. */
2277 /* Cater to broken compilers. */
2279 {
2280 /* This call returns a big structure. */
2283 #ifdef PCC_STATIC_STRUCT_RETURN
2284 {
2286 /* Easier than making that case work right. */
2288 {
2289 /* In case this is a static function, note that it has been
2290 used. */
2294 }
2295 }
2297 {
2301 {
2302 /* The structure value address arg is already in actparms.
2303 Pull it out. It might be nice to just leave it there, but
2304 we need to set structure_value_addr. */
2309 }
2312 else
2313 {
2314 /* For variable-sized objects, we must be called with a target
2315 specified. If we were to allocate space on the stack here,
2316 we would have no way of knowing when to free it. */
2322 }
2323 }
2325 }
2327 /* If called function is inline, try to integrate it. */
2330 {
2333 structure_value_addr);
2336 }
2338 /* Figure out the amount to which the stack should be aligned. */
2341 {
2345 }
2347 /* Operand 0 is a pointer-to-function; get the type of the function. */
2353 /* Munge the tree to split complex arguments into their imaginary
2354 and real parts. */
2356 {
2359 }
2360 else
2363 /* See if this is a call to a function that can return more than once
2364 or a call to longjmp or malloc. */
2370 /* If struct_value_rtx is 0, it means pass the address
2371 as if it were an extra parameter. */
2373 {
2374 /* If structure_value_addr is a REG other than
2375 virtual_outgoing_args_rtx, we can use always use it. If it
2376 is not a REG, we must always copy it into a register.
2377 If it is virtual_outgoing_args_rtx, we must copy it to another
2378 register in some cases. */
2380 || (ACCUMULATE_OUTGOING_ARGS
2381 && stack_arg_under_construction
2386 actparms
2389 temp),
2390 actparms);
2392 }
2394 /* Count the arguments and set NUM_ACTUALS. */
2396 num_actuals++;
2398 /* Start updating where the next arg would go.
2400 On some machines (such as the PA) indirect calls have a different
2401 calling convention than normal calls. The last argument in
2402 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2403 or not. */
2406 /* Compute number of named args.
2407 Normally, don't include the last named arg if anonymous args follow.
2408 We do include the last named arg if
2409 targetm.calls.strict_argument_naming() returns nonzero.
2410 (If no anonymous args follow, the result of list_length is actually
2411 one too large. This is harmless.)
2413 If targetm.calls.pretend_outgoing_varargs_named() returns
2414 nonzero, and targetm.calls.strict_argument_naming() returns zero,
2415 this machine will be able to place unnamed args that were passed
2416 in registers into the stack. So treat all args as named. This
2417 allows the insns emitting for a specific argument list to be
2418 independent of the function declaration.
2420 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
2421 we do not have any reliable way to pass unnamed args in
2422 registers, so we must force them into memory. */
2427 n_named_args
2429 /* Don't include the last named arg. */
2431 /* Count the struct value address, if it is passed as a parm. */
2433 else
2434 /* If we know nothing, treat all args as named. */
2437 /* Make a vector to hold all the information about each arg. */
2441 /* Build up entries in the ARGS array, compute the size of the
2442 arguments into ARGS_SIZE, etc. */
2450 {
2451 /* If this function requires a variable-sized argument list, don't
2452 try to make a cse'able block for this call. We may be able to
2453 do this eventually, but it is too complicated to keep track of
2454 what insns go in the cse'able block and which don't. */
2458 }
2460 /* Now make final decision about preallocating stack space. */
2465 /* If the structure value address will reference the stack pointer, we
2466 must stabilize it. We don't need to do this if we know that we are
2467 not going to adjust the stack pointer in processing this call. */
2472 structure_value_addr))
2477 /* Tail calls can make things harder to debug, and we're traditionally
2478 pushed these optimizations into -O2. Don't try if we're already
2479 expanding a call, as that means we're an argument. Don't try if
2480 there's cleanups, as we know there's code to follow the call.
2482 If rtx_equal_function_value_matters is false, that means we've
2483 finished with regular parsing. Which means that some of the
2484 machinery we use to generate tail-calls is no longer in place.
2485 This is most often true of sjlj-exceptions, which we couldn't
2486 tail-call to anyway.
2488 If current_nesting_level () == 0, we're being called after
2489 the function body has been expanded. This can happen when
2490 setting up trampolines in expand_function_end. */
2492 || !flag_optimize_sibling_calls
2493 || !rtx_equal_function_value_matters
2499 /* Tail recursion fails, when we are not dealing with recursive calls. */
2505 /* Rest of purposes for tail call optimizations to fail. */
2507 #ifdef HAVE_sibcall_epilogue
2508 !HAVE_sibcall_epilogue
2509 #else
2510 1
2511 #endif
2512 || !try_tail_call
2513 /* Doing sibling call optimization needs some work, since
2514 structure_value_addr can be allocated on the stack.
2515 It does not seem worth the effort since few optimizable
2516 sibling calls will return a structure. */
2518 /* Check whether the target is able to optimize the call
2519 into a sibcall. */
2521 /* Functions that do not return exactly once may not be sibcall
2522 optimized. */
2525 /* If the called function is nested in the current one, it might access
2526 some of the caller's arguments, but could clobber them beforehand if
2527 the argument areas are shared. */
2529 /* If this function requires more stack slots than the current
2530 function, we cannot change it into a sibling call. */
2532 /* If the callee pops its own arguments, then it must pop exactly
2533 the same number of arguments as the current function. */
2537 current_function_args_size))
2542 {
2545 /* Ok, we're going to give the tail call the old college try.
2546 This means we're going to evaluate the function arguments
2547 up to three times. There are two degrees of badness we can
2548 encounter, those that can be unsaved and those that can't.
2549 (See unsafe_for_reeval commentary for details.)
2551 Generate a new argument list. Pass safe arguments through
2552 unchanged. For the easy badness wrap them in UNSAVE_EXPRs.
2553 For hard badness, evaluate them now and put their resulting
2554 rtx in a temporary VAR_DECL.
2556 initialize_argument_information has ordered the array for the
2557 order to be pushed, and we must remember this when reconstructing
2558 the original argument order. */
2561 {
2565 }
2566 else
2567 {
2571 }
2574 {
2576 /* We need to build actparms for optimize_tail_recursion. We can
2577 safely trash away TREE_PURPOSE, since it is unused by this
2578 function. */
2581 }
2582 /* Do the same for the function address if it is an expression. */
2585 /* Expanding one of those dangerous arguments could have added
2586 cleanups, but otherwise give it a whirl. */
2589 }
2591 /* Generate a tail recursion sequence when calling ourselves. */
2594 {
2595 /* We want to emit any pending stack adjustments before the tail
2596 recursion "call". That way we know any adjustment after the tail
2597 recursion call can be ignored if we indeed use the tail recursion
2598 call expansion. */
2602 /* Emit any queued insns now; otherwise they would end up in
2603 only one of the alternates. */
2606 /* Use a new sequence to hold any RTL we generate. We do not even
2607 know if we will use this RTL yet. The final decision can not be
2608 made until after RTL generation for the entire function is
2609 complete. */
2611 /* If expanding any of the arguments creates cleanups, we can't
2612 do a tailcall. So, we'll need to pop the pending cleanups
2613 list. If, however, all goes well, and there are no cleanups
2614 then the call to expand_start_target_temps will have no
2615 effect. */
2618 {
2621 else
2623 }
2627 /* Restore the original pending stack adjustment for the sibling and
2628 normal call cases below. */
2631 }
2634 {
2635 /* A fork duplicates the profile information, and an exec discards
2636 it. We can't rely on fork/exec to be paired. So write out the
2637 profile information we have gathered so far, and clear it. */
2638 /* ??? When Linux's __clone is called with CLONE_VM set, profiling
2639 is subject to race conditions, just as with multithreaded
2640 programs. */
2643 }
2645 /* Ensure current function's preferred stack boundary is at least
2646 what we need. We don't have to increase alignment for recursive
2647 functions. */
2656 function_call_count++;
2658 /* We want to make two insn chains; one for a sibling call, the other
2659 for a normal call. We will select one of the two chains after
2660 initial RTL generation is complete. */
2662 {
2664 /* We want to emit any pending stack adjustments before the tail
2665 recursion "call". That way we know any adjustment after the tail
2666 recursion call can be ignored if we indeed use the tail recursion
2667 call expansion. */
2670 rtx insns;
2674 {
2675 /* Emit any queued insns now; otherwise they would end up in
2676 only one of the alternates. */
2679 /* State variables we need to save and restore between
2680 iterations. */
2683 }
2686 else
2689 /* Other state variables that we must reinitialize each time
2690 through the loop (that are not initialized by the loop itself). */
2694 /* Start a new sequence for the normal call case.
2696 From this point on, if the sibling call fails, we want to set
2697 sibcall_failure instead of continuing the loop. */
2701 {
2702 /* We know at this point that there are not currently any
2703 pending cleanups. If, however, in the process of evaluating
2704 the arguments we were to create some, we'll need to be
2705 able to get rid of them. */
2707 }
2709 /* Don't let pending stack adjusts add up to too much.
2710 Also, do all pending adjustments now if there is any chance
2711 this might be a call to alloca or if we are expanding a sibling
2712 call sequence or if we are calling a function that is to return
2713 with stack pointer depressed. */
2720 /* When calling a const function, we must pop the stack args right away,
2721 so that the pop is deleted or moved with the call. */
2723 NO_DEFER_POP;
2725 #ifdef FINAL_REG_PARM_STACK_SPACE
2728 #endif
2729 /* Precompute any arguments as needed. */
2733 /* Now we are about to start emitting insns that can be deleted
2734 if a libcall is deleted. */
2739 /* Compute the actual size of the argument block required. The variable
2740 and constant sizes must be combined, the size may have to be rounded,
2741 and there may be a minimum required size. When generating a sibcall
2742 pattern, do not round up, since we'll be re-using whatever space our
2743 caller provided. */
2744 unadjusted_args_size
2752 /* The argument block when performing a sibling call is the
2753 incoming argument block. */
2755 {
2757 argblock
2758 #ifdef STACK_GROWS_DOWNWARD
2760 #else
2762 #endif
2765 }
2767 /* If we have no actual push instructions, or shouldn't use them,
2768 make space for all args right now. */
2770 {
2772 {
2777 /* stack_arg_under_construction says whether a stack arg is
2778 being constructed at the old stack level. Pushing the stack
2779 gets a clean outgoing argument block. */
2782 }
2784 }
2785 else
2786 {
2787 /* Note that we must go through the motions of allocating an argument
2788 block even if the size is zero because we may be storing args
2789 in the area reserved for register arguments, which may be part of
2790 the stack frame. */
2794 /* Store the maximum argument space used. It will be pushed by
2795 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2796 checking). */
2802 {
2804 {
2805 /* Since the stack pointer will never be pushed, it is
2806 possible for the evaluation of a parm to clobber
2807 something we have already written to the stack.
2808 Since most function calls on RISC machines do not use
2809 the stack, this is uncommon, but must work correctly.
2811 Therefore, we save any area of the stack that was already
2812 written and that we are using. Here we set up to do this
2813 by making a new stack usage map from the old one. The
2814 actual save will be done by store_one_arg.
2816 Another approach might be to try to reorder the argument
2817 evaluations to avoid this conflicting stack usage. */
2819 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2820 /* Since we will be writing into the entire argument area,
2821 the map must be allocated for its entire size, not just
2822 the part that is the responsibility of the caller. */
2824 #endif
2826 #ifdef ARGS_GROW_DOWNWARD
2829 #else
2831 needed);
2832 #endif
2837 initial_highest_arg_in_use);
2841 (highest_outgoing_arg_in_use
2845 /* The address of the outgoing argument list must not be
2846 copied to a register here, because argblock would be left
2847 pointing to the wrong place after the call to
2848 allocate_dynamic_stack_space below. */
2851 }
2852 else
2853 {
2855 {
2856 /* Try to reuse some or all of the pending_stack_adjust
2857 to get this space. */
2858 needed
2859 = (combine_pending_stack_adjustment_and_call
2862 preferred_unit_stack_boundary));
2864 /* combine_pending_stack_adjustment_and_call computes
2865 an adjustment before the arguments are allocated.
2866 Account for them and see whether or not the stack
2867 needs to go up or down. */
2871 {
2872 /* We're releasing stack space. */
2873 /* ??? We can avoid any adjustment at all if we're
2874 already aligned. FIXME. */
2878 }
2879 else
2880 /* We need to allocate space. We'll do that in
2881 push_block below. */
2883 }
2885 /* Special case this because overhead of `push_block' in
2886 this case is non-trivial. */
2889 else
2890 {
2892 #ifdef ARGS_GROW_DOWNWARD
2894 #endif
2895 }
2897 /* We only really need to call `copy_to_reg' in the case
2898 where push insns are going to be used to pass ARGBLOCK
2899 to a function call in ARGS. In that case, the stack
2900 pointer changes value from the allocation point to the
2901 call point, and hence the value of
2902 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2903 as well always do it. */
2905 }
2906 }
2907 }
2910 {
2911 /* The save/restore code in store_one_arg handles all
2912 cases except one: a constructor call (including a C
2913 function returning a BLKmode struct) to initialize
2914 an argument. */
2916 {
2917 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2920 #else
2922 #endif
2924 {
2926 NULL_RTX);
2930 /* stack_arg_under_construction says whether a stack
2931 arg is being constructed at the old stack level.
2932 Pushing the stack gets a clean outgoing argument
2933 block. */
2934 old_stack_arg_under_construction
2937 /* Make a new map for the new argument list. */
2941 }
2943 BITS_PER_UNIT);
2944 }
2946 /* If argument evaluation might modify the stack pointer,
2947 copy the address of the argument list to a register. */
2950 {
2953 }
2954 }
2958 /* If we push args individually in reverse order, perform stack alignment
2959 before the first push (the last arg). */
2962 {
2963 /* When the stack adjustment is pending, we get better code
2964 by combining the adjustments. */
2968 {
2969 pending_stack_adjust
2970 = (combine_pending_stack_adjustment_and_call
2973 preferred_unit_stack_boundary));
2975 }
2979 }
2980 /* Now that the stack is properly aligned, pops can't safely
2981 be deferred during the evaluation of the arguments. */
2982 NO_DEFER_POP;
2986 /* Figure out the register where the value, if any, will come back. */
2990 {
2994 else
2996 }
2998 /* Precompute all register parameters. It isn't safe to compute anything
2999 once we have started filling any specific hard regs. */
3002 #ifdef REG_PARM_STACK_SPACE
3003 /* Save the fixed argument area if it's part of the caller's frame and
3004 is clobbered by argument setup for this call. */
3008 #endif
3010 /* Now store (and compute if necessary) all non-register parms.
3011 These come before register parms, since they can require block-moves,
3012 which could clobber the registers used for register parms.
3013 Parms which have partial registers are not stored here,
3014 but we do preallocate space here if they want that. */
3018 {
3023 reg_parm_stack_space)
3035 call_fusage);
3036 }
3038 /* If we have a parm that is passed in registers but not in memory
3039 and whose alignment does not permit a direct copy into registers,
3040 make a group of pseudos that correspond to each register that we
3041 will later fill. */
3045 /* Now store any partially-in-registers parm.
3046 This is the last place a block-move can happen. */
3050 {
3055 reg_parm_stack_space)
3060 }
3062 /* If we pushed args in forward order, perform stack alignment
3063 after pushing the last arg. */
3068 /* If register arguments require space on the stack and stack space
3069 was not preallocated, allocate stack space here for arguments
3070 passed in registers. */
3071 #ifdef OUTGOING_REG_PARM_STACK_SPACE
3075 #endif
3077 /* Pass the function the address in which to return a
3078 structure value. */
3080 {
3081 structure_value_addr
3086 NULL_RTX)));
3090 }
3098 /* Perform postincrements before actually calling the function. */
3101 /* Save a pointer to the last insn before the call, so that we can
3102 later safely search backwards to find the CALL_INSN. */
3105 /* Set up next argument register. For sibling calls on machines
3106 with register windows this should be the incoming register. */
3107 #ifdef FUNCTION_INCOMING_ARG
3111 else
3112 #endif
3116 /* All arguments and registers used for the call must be set up by
3117 now! */
3119 /* Stack must be properly aligned now. */
3123 /* Generate the actual call instruction. */
3129 /* If call is cse'able, make appropriate pair of reg-notes around it.
3130 Test valreg so we don't crash; may safely ignore `const'
3131 if return type is void. Disable for PARALLEL return values, because
3132 we have no way to move such values into a pseudo register. */
3134 {
3135 rtx insns;
3136 rtx insn;
3141 /* Expansion of block moves possibly introduced a loop that may
3142 not appear inside libcall block. */
3148 {
3151 }
3152 else
3153 {
3157 /* Mark the return value as a pointer if needed. */
3164 && fndecl
3172 else
3173 {
3174 /* Construct an "equal form" for the value which
3175 mentions all the arguments in order as well as
3176 the function name. */
3187 note);
3188 }
3192 }
3193 }
3195 {
3199 /* The return value from a malloc-like function is a pointer. */
3205 /* The return value from a malloc-like function can not alias
3206 anything else. */
3211 /* Write out the sequence. */
3216 }
3218 /* For calls to `setjmp', etc., inform flow.c it should complain
3219 if nonvolatile values are live. For functions that cannot return,
3220 inform flow that control does not fall through. */
3223 {
3224 /* The barrier must be emitted
3225 immediately after the CALL_INSN. Some ports emit more
3226 than just a CALL_INSN above, so we must search for it here. */
3230 {
3232 /* There was no CALL_INSN? */
3235 }
3239 /* Stack adjustments after a noreturn call are dead code.
3240 However when NO_DEFER_POP is in effect, we must preserve
3241 stack_pointer_delta. */
3243 {
3246 }
3247 }
3252 /* If value type not void, return an rtx for the value. */
3254 /* If there are cleanups to be called, don't use a hard reg as target.
3255 We need to double check this and see if it matters anymore. */
3257 {
3262 }
3268 {
3270 {
3271 target
3274 structure_value_addr));
3276 }
3277 }
3279 {
3280 /* This is the special C++ case where we need to
3281 know what the true target was. We take care to
3282 never use this value more than once in one expression. */
3286 }
3287 /* Handle calls that return values in multiple non-contiguous locations.
3288 The Irix 6 ABI has examples of this. */
3290 {
3291 /* Second condition is added because "target" is freed at the
3292 the end of "pass0" for -O2 when call is made to
3293 expand_end_target_temps (). Its "in_use" flag has been set
3294 to false, so allocate a new temp. */
3296 {
3297 /* This will only be assigned once, so it can be readonly. */
3305 }
3311 /* We can not support sibling calls for this case. */
3313 }
3317 {
3318 /* TARGET and VALREG cannot be equal at this point because the
3319 latter would not have REG_FUNCTION_VALUE_P true, while the
3320 former would if it were referring to the same register.
3322 If they refer to the same register, this move will be a no-op,
3323 except when function inlining is being done. */
3326 /* If we are setting a MEM, this code must be executed. Since it is
3327 emitted after the call insn, sibcall optimization cannot be
3328 performed in that case. */
3331 }
3333 {
3336 /* We can not support sibling calls for this case. */
3338 }
3339 else
3340 {
3345 }
3348 {
3349 /* If we promoted this return value, make the proper SUBREG. TARGET
3350 might be const0_rtx here, so be careful. */
3354 {
3359 /* If we don't promote as expected, something is wrong. */
3367 {
3374 }
3378 }
3379 }
3381 /* If size of args is variable or this was a constructor call for a stack
3382 argument, restore saved stack-pointer value. */
3385 {
3393 }
3395 {
3396 #ifdef REG_PARM_STACK_SPACE
3400 #endif
3402 /* If we saved any argument areas, restore them. */
3405 {
3407 rtx stack_area
3414 else
3417 BLOCK_OP_CALL_PARM);
3418 }
3422 }
3424 /* If this was alloca, record the new stack level for nonlocal gotos.
3425 Check for the handler slots since we might not have a save area
3426 for non-local gotos. */
3431 /* Free up storage we no longer need. */
3437 {
3438 /* Undo the fake expand_start_target_temps we did earlier. If
3439 there had been any cleanups created, we've already set
3440 sibcall_failure. */
3442 }
3444 /* If this function is returning into a memory location marked as
3445 readonly, it means it is initializing that location. We normally treat
3446 functions as not clobbering such locations, so we need to specify that
3447 this one does. We do this by adding the appropriate CLOBBER to the
3448 CALL_INSN function usage list. This cannot be done by emitting a
3449 standalone CLOBBER after the call because the latter would be ignored
3450 by at least the delay slot scheduling pass. We do this now instead of
3451 adding to call_fusage before the call to emit_call_1 because TARGET
3452 may be modified in the meantime. */
3455 add_function_usage_to
3458 NULL_RTX));
3464 {
3467 /* Restore the pending stack adjustment now that we have
3468 finished generating the sibling call sequence. */
3473 /* Prepare arg structure for next iteration. */
3475 {
3479 }
3482 }
3483 else
3484 {
3487 /* Verify that we've deallocated all the stack we used. */
3492 }
3494 /* If something prevents making this a sibling call,
3495 zero out the sequence. */
3498 }
3500 /* The function optimize_sibling_and_tail_recursive_calls doesn't
3501 handle CALL_PLACEHOLDERs inside other CALL_PLACEHOLDERs. This
3502 can happen if the arguments to this function call an inline
3503 function who's expansion contains another CALL_PLACEHOLDER.
3505 If there are any C_Ps in any of these sequences, replace them
3506 with their normal call. */
3523 /* If this was a potential tail recursion site, then emit a
3524 CALL_PLACEHOLDER with the normal and the tail recursion streams.
3525 One of them will be selected later. */
3527 {
3528 /* The tail recursion label must be kept around. We could expose
3529 its use in the CALL_PLACEHOLDER, but that creates unwanted edges
3530 and makes determining true tail recursion sites difficult.
3532 So we set LABEL_PRESERVE_P here, then clear it when we select
3533 one of the call sequences after rtl generation is complete. */
3537 tail_call_insns,
3538 tail_recursion_insns,
3539 tail_recursion_label));
3540 }
3541 else
3544 currently_expanding_call--;
3546 /* If this function returns with the stack pointer depressed, ensure
3547 this block saves and restores the stack pointer, show it was
3548 changed, and adjust for any outgoing arg space. */
3550 {
3555 }
3558 }
3560 /* Traverse an argument list in VALUES and expand all complex
3561 arguments into their components. */
3562 tree
3564 {
3565 tree p;
3570 {
3572 tree complex_type;
3579 {
3580 tree subtype;
3594 /* Skip the newly created node. */
3596 }
3597 }
3600 }
3602 /* Traverse a list of TYPES and expand all complex types into their
3603 components. */
3604 tree
3606 {
3607 tree p;
3612 {
3616 {
3619 /* Rewrite complex type with component type. */
3623 /* Add another component type for the imaginary part. */
3628 /* Skip the newly created node. */
3630 }
3631 }
3634 }
3635 \f
3636 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3637 The RETVAL parameter specifies whether return value needs to be saved, other
3638 parameters are documented in the emit_library_call function below. */
3640 static rtx
3644 {
3645 /* Total size in bytes of all the stack-parms scanned so far. */
3647 /* Size of arguments before any adjustments (such as rounding). */
3650 rtx fun;
3654 CUMULATIVE_ARGS args_so_far;
3655 struct arg
3656 {
3657 rtx value;
3659 rtx reg;
3662 rtx save_area;
3663 };
3668 rtx valreg;
3674 rtx before_call;
3677 #ifdef REG_PARM_STACK_SPACE
3678 /* Define the boundary of the register parm stack space that needs to be
3679 save, if any. */
3682 #endif
3684 /* Size of the stack reserved for parameter registers. */
3690 #ifdef REG_PARM_STACK_SPACE
3691 #ifdef MAYBE_REG_PARM_STACK_SPACE
3693 #else
3695 #endif
3696 #endif
3698 /* By default, library functions can not throw. */
3702 {
3729 }
3732 /* Ensure current function's preferred stack boundary is at least
3733 what we need. */
3737 /* If this kind of value comes back in memory,
3738 decide where in memory it should come back. */
3740 {
3743 {
3744 #ifdef PCC_STATIC_STRUCT_RETURN
3745 rtx pointer_reg
3755 else
3757 #endif
3758 /* This call returns a big structure. */
3760 }
3761 }
3762 else
3765 /* ??? Unfinished: must pass the memory address as an argument. */
3767 /* Copy all the libcall-arguments out of the varargs data
3768 and into a vector ARGVEC.
3770 Compute how to pass each argument. We only support a very small subset
3771 of the full argument passing conventions to limit complexity here since
3772 library functions shouldn't have many args. */
3777 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3779 #else
3781 #endif
3788 /* Now we are about to start emitting insns that can be deleted
3789 if a libcall is deleted. */
3795 /* If there's a structure value address to be passed,
3796 either pass it in the special place, or pass it as an extra argument. */
3798 {
3800 nargs++;
3802 /* Make sure it is a reasonable operand for a move or push insn. */
3812 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3815 #endif
3818 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3820 #else
3822 #endif
3831 count++;
3832 }
3835 {
3839 /* We cannot convert the arg value to the mode the library wants here;
3840 must do it earlier where we know the signedness of the arg. */
3845 /* There's no need to call protect_from_queue, because
3846 either emit_move_insn or emit_push_insn will do that. */
3848 /* Make sure it is a reasonable operand for a move or push insn. */
3853 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
3855 {
3856 rtx slot;
3858 #ifdef FUNCTION_ARG_CALLEE_COPIES
3861 #endif
3862 ;
3864 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3865 functions, so we have to pretend this isn't such a function. */
3867 {
3871 }
3874 /* If this was a CONST function, it is now PURE since
3875 it now reads memory. */
3877 {
3880 }
3885 {
3889 }
3890 else
3891 {
3894 slot
3900 }
3904 call_fusage);
3908 slot),
3909 call_fusage);
3913 }
3914 #endif
3921 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3924 #else
3926 #endif
3929 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3931 #else
3933 #endif
3945 }
3947 #ifdef FINAL_REG_PARM_STACK_SPACE
3950 #endif
3951 /* If this machine requires an external definition for library
3952 functions, write one out. */
3957 + stack_pointer_delta
3959 / STACK_BYTES
3964 reg_parm_stack_space);
3966 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3968 #endif
3974 {
3975 /* Since the stack pointer will never be pushed, it is possible for
3976 the evaluation of a parm to clobber something we have already
3977 written to the stack. Since most function calls on RISC machines
3978 do not use the stack, this is uncommon, but must work correctly.
3980 Therefore, we save any area of the stack that was already written
3981 and that we are using. Here we set up to do this by making a new
3982 stack usage map from the old one.
3984 Another approach might be to try to reorder the argument
3985 evaluations to avoid this conflicting stack usage. */
3989 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3990 /* Since we will be writing into the entire argument area, the
3991 map must be allocated for its entire size, not just the part that
3992 is the responsibility of the caller. */
3994 #endif
3996 #ifdef ARGS_GROW_DOWNWARD
3999 #else
4001 needed);
4002 #endif
4007 initial_highest_arg_in_use);
4014 /* We must be careful to use virtual regs before they're instantiated,
4015 and real regs afterwards. Loop optimization, for example, can create
4016 new libcalls after we've instantiated the virtual regs, and if we
4017 use virtuals anyway, they won't match the rtl patterns. */
4021 else
4023 }
4024 else
4025 {
4028 }
4030 /* If we push args individually in reverse order, perform stack alignment
4031 before the first push (the last arg). */
4037 {
4040 }
4041 else
4042 {
4045 }
4047 #ifdef REG_PARM_STACK_SPACE
4049 {
4050 /* The argument list is the property of the called routine and it
4051 may clobber it. If the fixed area has been used for previous
4052 parameters, we must save and restore it. */
4055 }
4056 #endif
4058 /* Push the args that need to be pushed. */
4060 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4061 are to be pushed. */
4063 {
4071 {
4073 {
4074 /* If this is being stored into a pre-allocated, fixed-size,
4075 stack area, save any previous data at that location. */
4077 #ifdef ARGS_GROW_DOWNWARD
4078 /* stack_slot is negative, but we want to index stack_usage_map
4079 with positive values. */
4082 #else
4085 #endif
4088 /* Don't worry about things in the fixed argument area;
4089 it has already been saved. */
4093 i++;
4096 {
4097 /* We need to make a save area. */
4098 unsigned int size
4100 enum machine_mode save_mode
4102 rtx adr
4105 rtx stack_area
4109 {
4116 stack_area,
4118 BLOCK_OP_CALL_PARM);
4119 }
4120 else
4121 {
4125 }
4126 }
4127 }
4132 reg_parm_stack_space,
4135 /* Now mark the segment we just used. */
4140 NO_DEFER_POP;
4141 }
4142 }
4144 /* If we pushed args in forward order, perform stack alignment
4145 after pushing the last arg. */
4152 else
4157 /* Now load any reg parms into their regs. */
4159 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4160 are to be pushed. */
4162 {
4167 /* Handle calls that pass values in multiple non-contiguous
4168 locations. The PA64 has examples of this for library calls. */
4174 NO_DEFER_POP;
4175 }
4177 /* Any regs containing parms remain in use through the call. */
4179 {
4185 }
4187 /* Pass the function the address in which to return a structure value. */
4189 {
4193 NULL_RTX)));
4196 }
4198 /* Don't allow popping to be deferred, since then
4199 cse'ing of library calls could delete a call and leave the pop. */
4200 NO_DEFER_POP;
4204 /* Stack must be properly aligned now. */
4210 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4211 will set inhibit_defer_pop to that value. */
4212 /* The return type is needed to decide how many bytes the function pops.
4213 Signedness plays no role in that, so for simplicity, we pretend it's
4214 always signed. We also assume that the list of arguments passed has
4215 no impact, so we pretend it is unknown. */
4221 struct_value_size,
4223 valreg,
4226 /* For calls to `setjmp', etc., inform flow.c it should complain
4227 if nonvolatile values are live. For functions that cannot return,
4228 inform flow that control does not fall through. */
4231 {
4232 /* The barrier note must be emitted
4233 immediately after the CALL_INSN. Some ports emit more than
4234 just a CALL_INSN above, so we must search for it here. */
4238 {
4240 /* There was no CALL_INSN? */
4243 }
4246 }
4248 /* Now restore inhibit_defer_pop to its actual original value. */
4249 OK_DEFER_POP;
4251 /* If call is cse'able, make appropriate pair of reg-notes around it.
4252 Test valreg so we don't crash; may safely ignore `const'
4253 if return type is void. Disable for PARALLEL return values, because
4254 we have no way to move such values into a pseudo register. */
4256 {
4257 rtx insns;
4260 {
4264 }
4265 else
4266 {
4268 rtx temp;
4272 {
4277 }
4281 /* Construct an "equal form" for the value which mentions all the
4282 arguments in order as well as the function name. */
4295 note);
4300 }
4301 }
4304 /* Copy the value to the right place. */
4306 {
4308 {
4313 }
4315 {
4319 }
4322 else
4324 }
4327 {
4328 #ifdef REG_PARM_STACK_SPACE
4332 #endif
4334 /* If we saved any argument areas, restore them. */
4337 {
4348 BLOCK_OP_CALL_PARM);
4349 else
4351 }
4355 }
4359 }
4360 \f
4361 /* Output a library call to function FUN (a SYMBOL_REF rtx)
4362 (emitting the queue unless NO_QUEUE is nonzero),
4363 for a value of mode OUTMODE,
4364 with NARGS different arguments, passed as alternating rtx values
4365 and machine_modes to convert them to.
4366 The rtx values should have been passed through protect_from_queue already.
4368 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
4369 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
4370 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
4371 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
4372 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
4373 or other LCT_ value for other types of library calls. */
4375 void
4378 {
4384 }
4385 \f
4386 /* Like emit_library_call except that an extra argument, VALUE,
4387 comes second and says where to store the result.
4388 (If VALUE is zero, this function chooses a convenient way
4389 to return the value.
4391 This function returns an rtx for where the value is to be found.
4392 If VALUE is nonzero, VALUE is returned. */
4394 rtx
4398 {
4399 rtx result;
4408 }
4409 \f
4410 /* Store a single argument for a function call
4411 into the register or memory area where it must be passed.
4412 *ARG describes the argument value and where to pass it.
4414 ARGBLOCK is the address of the stack-block for all the arguments,
4415 or 0 on a machine where arguments are pushed individually.
4417 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4418 so must be careful about how the stack is used.
4420 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4421 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4422 that we need not worry about saving and restoring the stack.
4424 FNDECL is the declaration of the function we are calling.
4426 Return nonzero if this arg should cause sibcall failure,
4427 zero otherwise. */
4429 static int
4432 {
4443 /* Push a new temporary level for any temporaries we make for
4444 this argument. */
4448 {
4449 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4450 save any previous data at that location. */
4452 {
4453 #ifdef ARGS_GROW_DOWNWARD
4454 /* stack_slot is negative, but we want to index stack_usage_map
4455 with positive values. */
4458 else
4462 #else
4465 else
4469 #endif
4472 /* Don't worry about things in the fixed argument area;
4473 it has already been saved. */
4477 i++;
4480 {
4481 /* We need to make a save area. */
4488 {
4497 BLOCK_OP_CALL_PARM);
4498 }
4499 else
4500 {
4503 }
4504 }
4505 }
4506 }
4508 /* If this isn't going to be placed on both the stack and in registers,
4509 set up the register and number of words. */
4511 {
4514 else
4517 }
4520 /* Being passed entirely in a register. We shouldn't be called in
4521 this case. */
4524 /* If this arg needs special alignment, don't load the registers
4525 here. */
4529 /* If this is being passed partially in a register, we can't evaluate
4530 it directly into its stack slot. Otherwise, we can. */
4532 {
4533 /* stack_arg_under_construction is nonzero if a function argument is
4534 being evaluated directly into the outgoing argument list and
4535 expand_call must take special action to preserve the argument list
4536 if it is called recursively.
4538 For scalar function arguments stack_usage_map is sufficient to
4539 determine which stack slots must be saved and restored. Scalar
4540 arguments in general have pass_on_stack == 0.
4542 If this argument is initialized by a function which takes the
4543 address of the argument (a C++ constructor or a C function
4544 returning a BLKmode structure), then stack_usage_map is
4545 insufficient and expand_call must push the stack around the
4546 function call. Such arguments have pass_on_stack == 1.
4548 Note that it is always safe to set stack_arg_under_construction,
4549 but this generates suboptimal code if set when not needed. */
4552 stack_arg_under_construction++;
4555 (partial
4560 /* If we are promoting object (or for any other reason) the mode
4561 doesn't agree, convert the mode. */
4568 stack_arg_under_construction--;
4569 }
4571 /* Don't allow anything left on stack from computation
4572 of argument to alloca. */
4577 /* If the value is already in the stack slot, we are done. */
4578 ;
4580 {
4583 /* Argument is a scalar, not entirely passed in registers.
4584 (If part is passed in registers, arg->partial says how much
4585 and emit_push_insn will take care of putting it there.)
4587 Push it, and if its size is less than the
4588 amount of space allocated to it,
4589 also bump stack pointer by the additional space.
4590 Note that in C the default argument promotions
4591 will prevent such mismatches. */
4594 /* Compute how much space the push instruction will push.
4595 On many machines, pushing a byte will advance the stack
4596 pointer by a halfword. */
4597 #ifdef PUSH_ROUNDING
4599 #endif
4602 /* Compute how much space the argument should get:
4603 round up to a multiple of the alignment for arguments. */
4609 /* This isn't already where we want it on the stack, so put it there.
4610 This can either be done with push or copy insns. */
4616 /* Unless this is a partially-in-register argument, the argument is now
4617 in the stack. */
4620 }
4621 else
4622 {
4623 /* BLKmode, at least partly to be pushed. */
4627 rtx size_rtx;
4629 /* Pushing a nonscalar.
4630 If part is passed in registers, PARTIAL says how much
4631 and emit_push_insn will take care of putting it there. */
4633 /* Round its size up to a multiple
4634 of the allocation unit for arguments. */
4637 {
4640 }
4641 else
4642 {
4643 /* PUSH_ROUNDING has no effect on us, because
4644 emit_push_insn for BLKmode is careful to avoid it. */
4646 {
4647 /* Use the size of the elt to compute excess. */
4652 }
4653 else
4659 }
4661 /* Some types will require stricter alignment, which will be
4662 provided for elsewhere in argument layout. */
4665 /* When an argument is padded down, the block is aligned to
4666 PARM_BOUNDARY, but the actual argument isn't. */
4668 {
4672 {
4675 }
4676 }
4679 {
4680 /* emit_push_insn might not work properly if arg->value and
4681 argblock + arg->locate.offset areas overlap. */
4688 current_function_internal_arg_pointer
4690 {
4694 /* expand_call should ensure this. */
4699 {
4702 }
4704 {
4707 }
4708 }
4709 }
4716 /* Unless this is a partially-in-register argument, the argument is now
4717 in the stack.
4719 ??? Unlike the case above, in which we want the actual
4720 address of the data, so that we can load it directly into a
4721 register, here we want the address of the stack slot, so that
4722 it's properly aligned for word-by-word copying or something
4723 like that. It's not clear that this is always correct. */
4726 }
4728 /* Mark all slots this store used. */
4734 /* Once we have pushed something, pops can't safely
4735 be deferred during the rest of the arguments. */
4736 NO_DEFER_POP;
4738 /* ANSI doesn't require a sequence point here,
4739 but PCC has one, so this will avoid some problems. */
4742 /* Free any temporary slots made in processing this argument. Show
4743 that we might have taken the address of something and pushed that
4744 as an operand. */
4750 }
4752 /* Nonzero if we do not know how to pass TYPE solely in registers.
4753 We cannot do so in the following cases:
4755 - if the type has variable size
4756 - if the type is marked as addressable (it is required to be constructed
4757 into the stack)
4758 - if the padding and mode of the type is such that a copy into a register
4759 would put it into the wrong part of the register.
4761 Which padding can't be supported depends on the byte endianness.
4763 A value in a register is implicitly padded at the most significant end.
4764 On a big-endian machine, that is the lower end in memory.
4765 So a value padded in memory at the upper end can't go in a register.
4766 For a little-endian machine, the reverse is true. */
4768 bool
4770 {
4774 /* If the type has variable size... */
4778 /* If the type is marked as addressable (it is required
4779 to be constructed into the stack)... */
4783 /* If the padding and mode of the type is such that a copy into
4784 a register would put it into the wrong part of the register. */
4792 }