| blob | 6da115c5594944ab0359fd43fe9eb5ef622516eb |
1 /* Convert function calls to rtl insns, for GNU C compiler.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
20 02111-1307, USA. */
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 {
1604 #ifdef LOAD_ARGS_REVERSED
1606 #else
1608 #endif
1609 {
1613 {
1618 /* Set to non-negative if must move a word at a time, even if just
1619 one word (e.g, partial == 1 && mode == DFmode). Set to -1 if
1620 we just use a normal move insn. This value can be zero if the
1621 argument is a zero size structure with no fields. */
1626 {
1629 }
1630 else
1633 /* Handle calls that pass values in multiple non-contiguous
1634 locations. The Irix 6 ABI has examples of this. */
1637 {
1641 }
1643 /* If simple case, just do move. If normal partial, store_one_arg
1644 has already loaded the register for us. In all other cases,
1645 load the register(s) from memory. */
1648 {
1650 #ifdef BLOCK_REG_PADDING
1651 /* Handle case where we have a value that needs shifting
1652 up to the msb. eg. a QImode value and we're padding
1653 upward on a BYTES_BIG_ENDIAN machine. */
1657 {
1658 rtx x;
1661 /* Assigning REG here rather than a temp makes CALL_FUSAGE
1662 report the whole reg as used. Strictly speaking, the
1663 call only uses SIZE bytes at the msb end, but it doesn't
1664 seem worth generating rtl to say that. */
1670 }
1671 #endif
1672 }
1674 /* If we have pre-computed the values to put in the registers in
1675 the case of non-aligned structures, copy them in now. */
1683 {
1686 #ifdef BLOCK_REG_PADDING
1687 /* Handle a BLKmode that needs shifting. */
1690 {
1702 }
1703 else
1704 #endif
1706 }
1708 /* When a parameter is a block, and perhaps in other cases, it is
1709 possible that it did a load from an argument slot that was
1710 already clobbered. */
1715 /* Handle calls that pass values in multiple non-contiguous
1716 locations. The Irix 6 ABI has examples of this. */
1721 else
1723 }
1724 }
1725 }
1727 /* Try to integrate function. See expand_inline_function for documentation
1728 about the parameters. */
1730 static rtx
1733 {
1734 rtx temp;
1735 rtx before_call;
1740 #ifdef REG_PARM_STACK_SPACE
1741 #ifdef MAYBE_REG_PARM_STACK_SPACE
1743 #else
1745 #endif
1746 #endif
1754 structure_value_addr);
1758 /* If inlining succeeded, return. */
1760 {
1762 {
1763 /* If the outgoing argument list must be preserved, push
1764 the stack before executing the inlined function if it
1765 makes any calls. */
1771 ;
1774 {
1775 rtx first_insn
1779 /* Look for a call in the inline function code.
1780 If DECL_SAVED_INSNS (fndecl)->outgoing_args_size is
1781 nonzero then there is a call and it is not necessary
1782 to scan the insns. */
1790 {
1791 /* Reserve enough stack space so that the largest
1792 argument list of any function call in the inline
1793 function does not overlap the argument list being
1794 evaluated. This is usually an overestimate because
1795 allocate_dynamic_stack_space reserves space for an
1796 outgoing argument list in addition to the requested
1797 space, but there is no way to ask for stack space such
1798 that an argument list of a certain length can be
1799 safely constructed.
1801 Add the stack space reserved for register arguments, if
1802 any, in the inline function. What is really needed is the
1803 largest value of reg_parm_stack_space in the inline
1804 function, but that is not available. Using the current
1805 value of reg_parm_stack_space is wrong, but gives
1806 correct results on all supported machines. */
1819 }
1820 }
1821 }
1823 /* If the result is equivalent to TARGET, return TARGET to simplify
1824 checks in store_expr. They can be equivalent but not equal in the
1825 case of a function that returns BLKmode. */
1829 }
1831 /* If inlining failed, mark FNDECL as needing to be compiled
1832 separately after all. If function was declared inline,
1833 give a warning. */
1836 {
1839 }
1842 }
1844 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
1845 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
1846 bytes, then we would need to push some additional bytes to pad the
1847 arguments. So, we compute an adjust to the stack pointer for an
1848 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
1849 bytes. Then, when the arguments are pushed the stack will be perfectly
1850 aligned. ARGS_SIZE->CONSTANT is set to the number of bytes that should
1851 be popped after the call. Returns the adjustment. */
1853 static int
1857 {
1858 /* The number of bytes to pop so that the stack will be
1859 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
1860 HOST_WIDE_INT adjustment;
1861 /* The alignment of the stack after the arguments are pushed, if we
1862 just pushed the arguments without adjust the stack here. */
1863 HOST_WIDE_INT unadjusted_alignment;
1865 unadjusted_alignment
1869 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
1870 as possible -- leaving just enough left to cancel out the
1871 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
1872 PENDING_STACK_ADJUST is non-negative, and congruent to
1873 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
1875 /* Begin by trying to pop all the bytes. */
1876 unadjusted_alignment
1877 = (unadjusted_alignment
1880 /* Push enough additional bytes that the stack will be aligned
1881 after the arguments are pushed. */
1883 {
1886 else
1888 }
1890 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
1891 bytes after the call. The right number is the entire
1892 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
1893 by the arguments in the first place. */
1894 args_size->constant
1898 }
1900 /* Scan X expression if it does not dereference any argument slots
1901 we already clobbered by tail call arguments (as noted in stored_args_map
1902 bitmap).
1903 Return nonzero if X expression dereferences such argument slots,
1904 zero otherwise. */
1906 static int
1908 {
1909 RTX_CODE code;
1920 {
1925 current_function_internal_arg_pointer
1928 else
1931 #ifdef ARGS_GROW_DOWNWARD
1933 #endif
1941 }
1943 /* Scan all subexpressions. */
1946 {
1948 {
1951 }
1953 {
1957 }
1958 }
1960 }
1962 /* Scan sequence after INSN if it does not dereference any argument slots
1963 we already clobbered by tail call arguments (as noted in stored_args_map
1964 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
1965 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
1966 should be 0). Return nonzero if sequence after INSN dereferences such argument
1967 slots, zero otherwise. */
1969 static int
1971 {
1976 else
1985 {
1986 #ifdef ARGS_GROW_DOWNWARD
1988 #else
1990 #endif
1994 }
1996 }
1998 static tree
2000 {
2002 {
2011 {
2017 }
2022 }
2024 }
2027 /* If function value *VALUE was returned at the most significant end of a
2028 register, shift it towards the least significant end and convert it to
2029 TYPE's mode. Return true and update *VALUE if some action was needed.
2031 TYPE is the type of the function's return value, which is known not
2032 to have mode BLKmode. */
2034 static bool
2036 {
2038 {
2039 HOST_WIDE_INT shift;
2044 {
2049 }
2050 }
2052 }
2054 /* Generate all the code for a function call
2055 and return an rtx for its value.
2056 Store the value in TARGET (specified as an rtx) if convenient.
2057 If the value is stored in TARGET then TARGET is returned.
2058 If IGNORE is nonzero, then we ignore the value of the function call. */
2060 rtx
2062 {
2063 /* Nonzero if we are currently expanding a call. */
2066 /* List of actual parameters. */
2068 /* RTX for the function to be called. */
2069 rtx funexp;
2070 /* Sequence of insns to perform a tail recursive "call". */
2072 /* Sequence of insns to perform a normal "call". */
2074 /* Sequence of insns to perform a tail recursive "call". */
2076 /* Data type of the function. */
2077 tree funtype;
2078 tree type_arg_types;
2079 /* Declaration of the function being called,
2080 or 0 if the function is computed (not known by name). */
2082 rtx insn;
2087 /* Register in which non-BLKmode value will be returned,
2088 or 0 if no value or if value is BLKmode. */
2089 rtx valreg;
2090 /* Address where we should return a BLKmode value;
2091 0 if value not BLKmode. */
2093 /* Nonzero if that address is being passed by treating it as
2094 an extra, implicit first parameter. Otherwise,
2095 it is passed by being copied directly into struct_value_rtx. */
2097 /* Size of aggregate value wanted, or zero if none wanted
2098 or if we are using the non-reentrant PCC calling convention
2099 or expecting the value in registers. */
2101 /* Nonzero if called function returns an aggregate in memory PCC style,
2102 by returning the address of where to find it. */
2106 /* Number of actual parameters in this call, including struct value addr. */
2108 /* Number of named args. Args after this are anonymous ones
2109 and they must all go on the stack. */
2112 /* Vector of information about each argument.
2113 Arguments are numbered in the order they will be pushed,
2114 not the order they are written. */
2117 /* Total size in bytes of all the stack-parms scanned so far. */
2120 /* Size of arguments before any adjustments (such as rounding). */
2122 /* Data on reg parms scanned so far. */
2123 CUMULATIVE_ARGS args_so_far;
2124 /* Nonzero if a reg parm has been scanned. */
2126 /* Nonzero if this is an indirect function call. */
2128 /* Nonzero if we must avoid push-insns in the args for this call.
2129 If stack space is allocated for register parameters, but not by the
2130 caller, then it is preallocated in the fixed part of the stack frame.
2131 So the entire argument block must then be preallocated (i.e., we
2132 ignore PUSH_ROUNDING in that case). */
2136 /* Size of the stack reserved for parameter registers. */
2139 /* Address of space preallocated for stack parms
2140 (on machines that lack push insns), or 0 if space not preallocated. */
2143 /* Mask of ECF_ flags. */
2145 /* Nonzero if this is a call to an inline function. */
2147 #ifdef REG_PARM_STACK_SPACE
2148 /* Define the boundary of the register parm stack space that needs to be
2149 saved, if any. */
2152 #endif
2160 /* State variables to track stack modifications. */
2166 /* Some stack pointer alterations we make are performed via
2167 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2168 which we then also need to save/restore along the way. */
2171 rtx call_fusage;
2175 /* The alignment of the stack, in bits. */
2176 HOST_WIDE_INT preferred_stack_boundary;
2177 /* The alignment of the stack, in bytes. */
2178 HOST_WIDE_INT preferred_unit_stack_boundary;
2180 /* See if this is "nothrow" function call. */
2184 /* See if we can find a DECL-node for the actual function.
2185 As a result, decide whether this is a call to an integrable function. */
2189 {
2197 {
2198 /* In case this function later becomes inlinable,
2199 record that there was already a non-inline call to it.
2201 Use abstraction instead of setting TREE_ADDRESSABLE
2202 directly. */
2205 {
2208 }
2210 }
2219 }
2221 /* If we don't have specific function to call, see if we have a
2222 attributes set in the type. */
2223 else
2224 {
2231 }
2235 /* Warn if this value is an aggregate type,
2236 regardless of which calling convention we are using for it. */
2240 /* If the result of a pure or const function call is ignored (or void),
2241 and none of its arguments are volatile, we can avoid expanding the
2242 call and just evaluate the arguments for side-effects. */
2246 {
2248 tree arg;
2252 {
2255 }
2258 {
2263 }
2264 }
2266 #ifdef REG_PARM_STACK_SPACE
2267 #ifdef MAYBE_REG_PARM_STACK_SPACE
2269 #else
2271 #endif
2272 #endif
2274 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2277 #endif
2279 /* Set up a place to return a structure. */
2281 /* Cater to broken compilers. */
2283 {
2284 /* This call returns a big structure. */
2287 #ifdef PCC_STATIC_STRUCT_RETURN
2288 {
2290 /* Easier than making that case work right. */
2292 {
2293 /* In case this is a static function, note that it has been
2294 used. */
2298 }
2299 }
2301 {
2305 {
2306 /* The structure value address arg is already in actparms.
2307 Pull it out. It might be nice to just leave it there, but
2308 we need to set structure_value_addr. */
2313 }
2316 else
2317 {
2318 /* For variable-sized objects, we must be called with a target
2319 specified. If we were to allocate space on the stack here,
2320 we would have no way of knowing when to free it. */
2326 }
2327 }
2329 }
2331 /* If called function is inline, try to integrate it. */
2334 {
2337 structure_value_addr);
2340 }
2342 /* Figure out the amount to which the stack should be aligned. */
2345 {
2349 }
2351 /* Operand 0 is a pointer-to-function; get the type of the function. */
2357 /* Munge the tree to split complex arguments into their imaginary
2358 and real parts. */
2360 {
2363 }
2364 else
2367 /* See if this is a call to a function that can return more than once
2368 or a call to longjmp or malloc. */
2374 /* If struct_value_rtx is 0, it means pass the address
2375 as if it were an extra parameter. */
2377 {
2378 /* If structure_value_addr is a REG other than
2379 virtual_outgoing_args_rtx, we can use always use it. If it
2380 is not a REG, we must always copy it into a register.
2381 If it is virtual_outgoing_args_rtx, we must copy it to another
2382 register in some cases. */
2384 || (ACCUMULATE_OUTGOING_ARGS
2385 && stack_arg_under_construction
2390 actparms
2393 temp),
2394 actparms);
2396 }
2398 /* Count the arguments and set NUM_ACTUALS. */
2400 num_actuals++;
2402 /* Start updating where the next arg would go.
2404 On some machines (such as the PA) indirect calls have a different
2405 calling convention than normal calls. The last argument in
2406 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2407 or not. */
2410 /* Compute number of named args.
2411 Normally, don't include the last named arg if anonymous args follow.
2412 We do include the last named arg if STRICT_ARGUMENT_NAMING is nonzero.
2413 (If no anonymous args follow, the result of list_length is actually
2414 one too large. This is harmless.)
2416 If PRETEND_OUTGOING_VARARGS_NAMED is set and STRICT_ARGUMENT_NAMING is
2417 zero, this machine will be able to place unnamed args that were
2418 passed in registers into the stack. So treat all args as named.
2419 This allows the insns emitting for a specific argument list to be
2420 independent of the function declaration.
2422 If PRETEND_OUTGOING_VARARGS_NAMED is not set, we do not have any
2423 reliable way to pass unnamed args in registers, so we must force
2424 them into memory. */
2429 n_named_args
2431 /* Don't include the last named arg. */
2433 /* Count the struct value address, if it is passed as a parm. */
2435 else
2436 /* If we know nothing, treat all args as named. */
2439 /* Make a vector to hold all the information about each arg. */
2443 /* Build up entries in the ARGS array, compute the size of the
2444 arguments into ARGS_SIZE, etc. */
2452 {
2453 /* If this function requires a variable-sized argument list, don't
2454 try to make a cse'able block for this call. We may be able to
2455 do this eventually, but it is too complicated to keep track of
2456 what insns go in the cse'able block and which don't. */
2460 }
2462 /* Now make final decision about preallocating stack space. */
2467 /* If the structure value address will reference the stack pointer, we
2468 must stabilize it. We don't need to do this if we know that we are
2469 not going to adjust the stack pointer in processing this call. */
2474 structure_value_addr))
2479 /* Tail calls can make things harder to debug, and we're traditionally
2480 pushed these optimizations into -O2. Don't try if we're already
2481 expanding a call, as that means we're an argument. Don't try if
2482 there's cleanups, as we know there's code to follow the call.
2484 If rtx_equal_function_value_matters is false, that means we've
2485 finished with regular parsing. Which means that some of the
2486 machinery we use to generate tail-calls is no longer in place.
2487 This is most often true of sjlj-exceptions, which we couldn't
2488 tail-call to anyway.
2490 If current_nesting_level () == 0, we're being called after
2491 the function body has been expanded. This can happen when
2492 setting up trampolines in expand_function_end. */
2494 || !flag_optimize_sibling_calls
2495 || !rtx_equal_function_value_matters
2501 /* Tail recursion fails, when we are not dealing with recursive calls. */
2507 /* Rest of purposes for tail call optimizations to fail. */
2509 #ifdef HAVE_sibcall_epilogue
2510 !HAVE_sibcall_epilogue
2511 #else
2512 1
2513 #endif
2514 || !try_tail_call
2515 /* Doing sibling call optimization needs some work, since
2516 structure_value_addr can be allocated on the stack.
2517 It does not seem worth the effort since few optimizable
2518 sibling calls will return a structure. */
2520 /* Check whether the target is able to optimize the call
2521 into a sibcall. */
2523 /* Functions that do not return exactly once may not be sibcall
2524 optimized. */
2527 /* If the called function is nested in the current one, it might access
2528 some of the caller's arguments, but could clobber them beforehand if
2529 the argument areas are shared. */
2531 /* If this function requires more stack slots than the current
2532 function, we cannot change it into a sibling call. */
2534 /* If the callee pops its own arguments, then it must pop exactly
2535 the same number of arguments as the current function. */
2539 current_function_args_size))
2544 {
2547 /* Ok, we're going to give the tail call the old college try.
2548 This means we're going to evaluate the function arguments
2549 up to three times. There are two degrees of badness we can
2550 encounter, those that can be unsaved and those that can't.
2551 (See unsafe_for_reeval commentary for details.)
2553 Generate a new argument list. Pass safe arguments through
2554 unchanged. For the easy badness wrap them in UNSAVE_EXPRs.
2555 For hard badness, evaluate them now and put their resulting
2556 rtx in a temporary VAR_DECL.
2558 initialize_argument_information has ordered the array for the
2559 order to be pushed, and we must remember this when reconstructing
2560 the original argument order. */
2563 {
2567 }
2568 else
2569 {
2573 }
2576 {
2578 /* We need to build actparms for optimize_tail_recursion. We can
2579 safely trash away TREE_PURPOSE, since it is unused by this
2580 function. */
2583 }
2584 /* Do the same for the function address if it is an expression. */
2587 /* Expanding one of those dangerous arguments could have added
2588 cleanups, but otherwise give it a whirl. */
2591 }
2593 /* Generate a tail recursion sequence when calling ourselves. */
2596 {
2597 /* We want to emit any pending stack adjustments before the tail
2598 recursion "call". That way we know any adjustment after the tail
2599 recursion call can be ignored if we indeed use the tail recursion
2600 call expansion. */
2604 /* Emit any queued insns now; otherwise they would end up in
2605 only one of the alternates. */
2608 /* Use a new sequence to hold any RTL we generate. We do not even
2609 know if we will use this RTL yet. The final decision can not be
2610 made until after RTL generation for the entire function is
2611 complete. */
2613 /* If expanding any of the arguments creates cleanups, we can't
2614 do a tailcall. So, we'll need to pop the pending cleanups
2615 list. If, however, all goes well, and there are no cleanups
2616 then the call to expand_start_target_temps will have no
2617 effect. */
2620 {
2623 else
2625 }
2629 /* Restore the original pending stack adjustment for the sibling and
2630 normal call cases below. */
2633 }
2636 {
2637 /* A fork duplicates the profile information, and an exec discards
2638 it. We can't rely on fork/exec to be paired. So write out the
2639 profile information we have gathered so far, and clear it. */
2640 /* ??? When Linux's __clone is called with CLONE_VM set, profiling
2641 is subject to race conditions, just as with multithreaded
2642 programs. */
2645 }
2647 /* Ensure current function's preferred stack boundary is at least
2648 what we need. We don't have to increase alignment for recursive
2649 functions. */
2658 function_call_count++;
2660 /* We want to make two insn chains; one for a sibling call, the other
2661 for a normal call. We will select one of the two chains after
2662 initial RTL generation is complete. */
2664 {
2666 /* We want to emit any pending stack adjustments before the tail
2667 recursion "call". That way we know any adjustment after the tail
2668 recursion call can be ignored if we indeed use the tail recursion
2669 call expansion. */
2672 rtx insns;
2676 {
2677 /* Emit any queued insns now; otherwise they would end up in
2678 only one of the alternates. */
2681 /* State variables we need to save and restore between
2682 iterations. */
2685 }
2688 else
2691 /* Other state variables that we must reinitialize each time
2692 through the loop (that are not initialized by the loop itself). */
2696 /* Start a new sequence for the normal call case.
2698 From this point on, if the sibling call fails, we want to set
2699 sibcall_failure instead of continuing the loop. */
2703 {
2704 /* We know at this point that there are not currently any
2705 pending cleanups. If, however, in the process of evaluating
2706 the arguments we were to create some, we'll need to be
2707 able to get rid of them. */
2709 }
2711 /* Don't let pending stack adjusts add up to too much.
2712 Also, do all pending adjustments now if there is any chance
2713 this might be a call to alloca or if we are expanding a sibling
2714 call sequence or if we are calling a function that is to return
2715 with stack pointer depressed. */
2722 /* When calling a const function, we must pop the stack args right away,
2723 so that the pop is deleted or moved with the call. */
2725 NO_DEFER_POP;
2727 #ifdef FINAL_REG_PARM_STACK_SPACE
2730 #endif
2731 /* Precompute any arguments as needed. */
2735 /* Now we are about to start emitting insns that can be deleted
2736 if a libcall is deleted. */
2741 /* Compute the actual size of the argument block required. The variable
2742 and constant sizes must be combined, the size may have to be rounded,
2743 and there may be a minimum required size. When generating a sibcall
2744 pattern, do not round up, since we'll be re-using whatever space our
2745 caller provided. */
2746 unadjusted_args_size
2754 /* The argument block when performing a sibling call is the
2755 incoming argument block. */
2757 {
2759 argblock
2760 #ifdef STACK_GROWS_DOWNWARD
2762 #else
2764 #endif
2767 }
2769 /* If we have no actual push instructions, or shouldn't use them,
2770 make space for all args right now. */
2772 {
2774 {
2779 /* stack_arg_under_construction says whether a stack arg is
2780 being constructed at the old stack level. Pushing the stack
2781 gets a clean outgoing argument block. */
2784 }
2786 }
2787 else
2788 {
2789 /* Note that we must go through the motions of allocating an argument
2790 block even if the size is zero because we may be storing args
2791 in the area reserved for register arguments, which may be part of
2792 the stack frame. */
2796 /* Store the maximum argument space used. It will be pushed by
2797 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2798 checking). */
2804 {
2806 {
2807 /* Since the stack pointer will never be pushed, it is
2808 possible for the evaluation of a parm to clobber
2809 something we have already written to the stack.
2810 Since most function calls on RISC machines do not use
2811 the stack, this is uncommon, but must work correctly.
2813 Therefore, we save any area of the stack that was already
2814 written and that we are using. Here we set up to do this
2815 by making a new stack usage map from the old one. The
2816 actual save will be done by store_one_arg.
2818 Another approach might be to try to reorder the argument
2819 evaluations to avoid this conflicting stack usage. */
2821 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2822 /* Since we will be writing into the entire argument area,
2823 the map must be allocated for its entire size, not just
2824 the part that is the responsibility of the caller. */
2826 #endif
2828 #ifdef ARGS_GROW_DOWNWARD
2831 #else
2833 needed);
2834 #endif
2839 initial_highest_arg_in_use);
2843 (highest_outgoing_arg_in_use
2847 /* The address of the outgoing argument list must not be
2848 copied to a register here, because argblock would be left
2849 pointing to the wrong place after the call to
2850 allocate_dynamic_stack_space below. */
2853 }
2854 else
2855 {
2857 {
2858 /* Try to reuse some or all of the pending_stack_adjust
2859 to get this space. */
2860 needed
2861 = (combine_pending_stack_adjustment_and_call
2864 preferred_unit_stack_boundary));
2866 /* combine_pending_stack_adjustment_and_call computes
2867 an adjustment before the arguments are allocated.
2868 Account for them and see whether or not the stack
2869 needs to go up or down. */
2873 {
2874 /* We're releasing stack space. */
2875 /* ??? We can avoid any adjustment at all if we're
2876 already aligned. FIXME. */
2880 }
2881 else
2882 /* We need to allocate space. We'll do that in
2883 push_block below. */
2885 }
2887 /* Special case this because overhead of `push_block' in
2888 this case is non-trivial. */
2891 else
2892 {
2894 #ifdef ARGS_GROW_DOWNWARD
2896 #endif
2897 }
2899 /* We only really need to call `copy_to_reg' in the case
2900 where push insns are going to be used to pass ARGBLOCK
2901 to a function call in ARGS. In that case, the stack
2902 pointer changes value from the allocation point to the
2903 call point, and hence the value of
2904 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2905 as well always do it. */
2907 }
2908 }
2909 }
2912 {
2913 /* The save/restore code in store_one_arg handles all
2914 cases except one: a constructor call (including a C
2915 function returning a BLKmode struct) to initialize
2916 an argument. */
2918 {
2919 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2922 #else
2924 #endif
2926 {
2928 NULL_RTX);
2932 /* stack_arg_under_construction says whether a stack
2933 arg is being constructed at the old stack level.
2934 Pushing the stack gets a clean outgoing argument
2935 block. */
2936 old_stack_arg_under_construction
2939 /* Make a new map for the new argument list. */
2943 }
2945 BITS_PER_UNIT);
2946 }
2948 /* If argument evaluation might modify the stack pointer,
2949 copy the address of the argument list to a register. */
2952 {
2955 }
2956 }
2960 /* If we push args individually in reverse order, perform stack alignment
2961 before the first push (the last arg). */
2964 {
2965 /* When the stack adjustment is pending, we get better code
2966 by combining the adjustments. */
2970 {
2971 pending_stack_adjust
2972 = (combine_pending_stack_adjustment_and_call
2975 preferred_unit_stack_boundary));
2977 }
2981 }
2982 /* Now that the stack is properly aligned, pops can't safely
2983 be deferred during the evaluation of the arguments. */
2984 NO_DEFER_POP;
2988 /* Figure out the register where the value, if any, will come back. */
2992 {
2996 else
2998 }
3000 /* Precompute all register parameters. It isn't safe to compute anything
3001 once we have started filling any specific hard regs. */
3004 #ifdef REG_PARM_STACK_SPACE
3005 /* Save the fixed argument area if it's part of the caller's frame and
3006 is clobbered by argument setup for this call. */
3010 #endif
3012 /* Now store (and compute if necessary) all non-register parms.
3013 These come before register parms, since they can require block-moves,
3014 which could clobber the registers used for register parms.
3015 Parms which have partial registers are not stored here,
3016 but we do preallocate space here if they want that. */
3020 {
3025 reg_parm_stack_space)
3030 }
3032 /* If we have a parm that is passed in registers but not in memory
3033 and whose alignment does not permit a direct copy into registers,
3034 make a group of pseudos that correspond to each register that we
3035 will later fill. */
3039 /* Now store any partially-in-registers parm.
3040 This is the last place a block-move can happen. */
3044 {
3049 reg_parm_stack_space)
3054 }
3056 /* If we pushed args in forward order, perform stack alignment
3057 after pushing the last arg. */
3062 /* If register arguments require space on the stack and stack space
3063 was not preallocated, allocate stack space here for arguments
3064 passed in registers. */
3065 #ifdef OUTGOING_REG_PARM_STACK_SPACE
3069 #endif
3071 /* Pass the function the address in which to return a
3072 structure value. */
3074 {
3075 structure_value_addr
3080 NULL_RTX)));
3084 }
3092 /* Perform postincrements before actually calling the function. */
3095 /* Save a pointer to the last insn before the call, so that we can
3096 later safely search backwards to find the CALL_INSN. */
3099 /* Set up next argument register. For sibling calls on machines
3100 with register windows this should be the incoming register. */
3101 #ifdef FUNCTION_INCOMING_ARG
3105 else
3106 #endif
3110 /* All arguments and registers used for the call must be set up by
3111 now! */
3113 /* Stack must be properly aligned now. */
3117 /* Generate the actual call instruction. */
3123 /* If call is cse'able, make appropriate pair of reg-notes around it.
3124 Test valreg so we don't crash; may safely ignore `const'
3125 if return type is void. Disable for PARALLEL return values, because
3126 we have no way to move such values into a pseudo register. */
3128 {
3129 rtx insns;
3130 rtx insn;
3135 /* Expansion of block moves possibly introduced a loop that may
3136 not appear inside libcall block. */
3142 {
3145 }
3146 else
3147 {
3151 /* Mark the return value as a pointer if needed. */
3156 /* Construct an "equal form" for the value which mentions all the
3157 arguments in order as well as the function name. */
3170 note);
3175 }
3176 }
3178 {
3182 /* The return value from a malloc-like function is a pointer. */
3188 /* The return value from a malloc-like function can not alias
3189 anything else. */
3194 /* Write out the sequence. */
3199 }
3201 /* For calls to `setjmp', etc., inform flow.c it should complain
3202 if nonvolatile values are live. For functions that cannot return,
3203 inform flow that control does not fall through. */
3206 {
3207 /* The barrier must be emitted
3208 immediately after the CALL_INSN. Some ports emit more
3209 than just a CALL_INSN above, so we must search for it here. */
3213 {
3215 /* There was no CALL_INSN? */
3218 }
3222 /* Stack adjustments after a noreturn call are dead code.
3223 However when NO_DEFER_POP is in effect, we must preserve
3224 stack_pointer_delta. */
3226 {
3229 }
3230 }
3235 /* If value type not void, return an rtx for the value. */
3237 /* If there are cleanups to be called, don't use a hard reg as target.
3238 We need to double check this and see if it matters anymore. */
3240 {
3245 }
3251 {
3253 {
3254 target
3257 structure_value_addr));
3259 }
3260 }
3262 {
3263 /* This is the special C++ case where we need to
3264 know what the true target was. We take care to
3265 never use this value more than once in one expression. */
3269 }
3270 /* Handle calls that return values in multiple non-contiguous locations.
3271 The Irix 6 ABI has examples of this. */
3273 {
3274 /* Second condition is added because "target" is freed at the
3275 the end of "pass0" for -O2 when call is made to
3276 expand_end_target_temps (). Its "in_use" flag has been set
3277 to false, so allocate a new temp. */
3279 {
3280 /* This will only be assigned once, so it can be readonly. */
3288 }
3294 /* We can not support sibling calls for this case. */
3296 }
3300 {
3301 /* TARGET and VALREG cannot be equal at this point because the
3302 latter would not have REG_FUNCTION_VALUE_P true, while the
3303 former would if it were referring to the same register.
3305 If they refer to the same register, this move will be a no-op,
3306 except when function inlining is being done. */
3309 /* If we are setting a MEM, this code must be executed. Since it is
3310 emitted after the call insn, sibcall optimization cannot be
3311 performed in that case. */
3314 }
3316 {
3319 /* We can not support sibling calls for this case. */
3321 }
3322 else
3323 {
3328 }
3331 {
3332 /* If we promoted this return value, make the proper SUBREG. TARGET
3333 might be const0_rtx here, so be careful. */
3337 {
3342 /* If we don't promote as expected, something is wrong. */
3350 {
3357 }
3361 }
3362 }
3364 /* If size of args is variable or this was a constructor call for a stack
3365 argument, restore saved stack-pointer value. */
3368 {
3376 }
3378 {
3379 #ifdef REG_PARM_STACK_SPACE
3383 #endif
3385 /* If we saved any argument areas, restore them. */
3388 {
3390 rtx stack_area
3397 else
3400 BLOCK_OP_CALL_PARM);
3401 }
3405 }
3407 /* If this was alloca, record the new stack level for nonlocal gotos.
3408 Check for the handler slots since we might not have a save area
3409 for non-local gotos. */
3414 /* Free up storage we no longer need. */
3420 {
3421 /* Undo the fake expand_start_target_temps we did earlier. If
3422 there had been any cleanups created, we've already set
3423 sibcall_failure. */
3425 }
3427 /* If this function is returning into a memory location marked as
3428 readonly, it means it is initializing that location. We normally treat
3429 functions as not clobbering such locations, so we need to specify that
3430 this one does. We do this by adding the appropriate CLOBBER to the
3431 CALL_INSN function usage list. This cannot be done by emitting a
3432 standalone CLOBBER after the call because the latter would be ignored
3433 by at least the delay slot scheduling pass. We do this now instead of
3434 adding to call_fusage before the call to emit_call_1 because TARGET
3435 may be modified in the meantime. */
3438 add_function_usage_to
3441 NULL_RTX));
3447 {
3450 /* Restore the pending stack adjustment now that we have
3451 finished generating the sibling call sequence. */
3456 /* Prepare arg structure for next iteration. */
3458 {
3462 }
3465 }
3466 else
3467 {
3470 /* Verify that we've deallocated all the stack we used. */
3475 }
3477 /* If something prevents making this a sibling call,
3478 zero out the sequence. */
3481 }
3483 /* The function optimize_sibling_and_tail_recursive_calls doesn't
3484 handle CALL_PLACEHOLDERs inside other CALL_PLACEHOLDERs. This
3485 can happen if the arguments to this function call an inline
3486 function who's expansion contains another CALL_PLACEHOLDER.
3488 If there are any C_Ps in any of these sequences, replace them
3489 with their normal call. */
3506 /* If this was a potential tail recursion site, then emit a
3507 CALL_PLACEHOLDER with the normal and the tail recursion streams.
3508 One of them will be selected later. */
3510 {
3511 /* The tail recursion label must be kept around. We could expose
3512 its use in the CALL_PLACEHOLDER, but that creates unwanted edges
3513 and makes determining true tail recursion sites difficult.
3515 So we set LABEL_PRESERVE_P here, then clear it when we select
3516 one of the call sequences after rtl generation is complete. */
3520 tail_call_insns,
3521 tail_recursion_insns,
3522 tail_recursion_label));
3523 }
3524 else
3527 currently_expanding_call--;
3529 /* If this function returns with the stack pointer depressed, ensure
3530 this block saves and restores the stack pointer, show it was
3531 changed, and adjust for any outgoing arg space. */
3533 {
3538 }
3541 }
3543 /* Traverse an argument list in VALUES and expand all complex
3544 arguments into their components. */
3545 tree
3547 {
3548 tree p;
3553 {
3555 tree complex_type;
3562 {
3563 tree subtype;
3577 /* Skip the newly created node. */
3579 }
3580 }
3583 }
3585 /* Traverse a list of TYPES and expand all complex types into their
3586 components. */
3587 tree
3589 {
3590 tree p;
3595 {
3599 {
3602 /* Rewrite complex type with component type. */
3606 /* Add another component type for the imaginary part. */
3611 /* Skip the newly created node. */
3613 }
3614 }
3617 }
3618 \f
3619 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3620 The RETVAL parameter specifies whether return value needs to be saved, other
3621 parameters are documented in the emit_library_call function below. */
3623 static rtx
3627 {
3628 /* Total size in bytes of all the stack-parms scanned so far. */
3630 /* Size of arguments before any adjustments (such as rounding). */
3633 rtx fun;
3637 CUMULATIVE_ARGS args_so_far;
3638 struct arg
3639 {
3640 rtx value;
3642 rtx reg;
3645 rtx save_area;
3646 };
3651 rtx valreg;
3657 rtx before_call;
3660 #ifdef REG_PARM_STACK_SPACE
3661 /* Define the boundary of the register parm stack space that needs to be
3662 save, if any. */
3665 #endif
3667 /* Size of the stack reserved for parameter registers. */
3673 #ifdef REG_PARM_STACK_SPACE
3674 #ifdef MAYBE_REG_PARM_STACK_SPACE
3676 #else
3678 #endif
3679 #endif
3681 /* By default, library functions can not throw. */
3685 {
3712 }
3715 /* Ensure current function's preferred stack boundary is at least
3716 what we need. */
3720 /* If this kind of value comes back in memory,
3721 decide where in memory it should come back. */
3723 {
3726 {
3727 #ifdef PCC_STATIC_STRUCT_RETURN
3728 rtx pointer_reg
3738 else
3740 #endif
3741 /* This call returns a big structure. */
3743 }
3744 }
3745 else
3748 /* ??? Unfinished: must pass the memory address as an argument. */
3750 /* Copy all the libcall-arguments out of the varargs data
3751 and into a vector ARGVEC.
3753 Compute how to pass each argument. We only support a very small subset
3754 of the full argument passing conventions to limit complexity here since
3755 library functions shouldn't have many args. */
3760 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3762 #else
3764 #endif
3771 /* Now we are about to start emitting insns that can be deleted
3772 if a libcall is deleted. */
3778 /* If there's a structure value address to be passed,
3779 either pass it in the special place, or pass it as an extra argument. */
3781 {
3783 nargs++;
3785 /* Make sure it is a reasonable operand for a move or push insn. */
3795 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3798 #endif
3801 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3803 #else
3805 #endif
3814 count++;
3815 }
3818 {
3822 /* We cannot convert the arg value to the mode the library wants here;
3823 must do it earlier where we know the signedness of the arg. */
3828 /* There's no need to call protect_from_queue, because
3829 either emit_move_insn or emit_push_insn will do that. */
3831 /* Make sure it is a reasonable operand for a move or push insn. */
3836 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
3838 {
3839 rtx slot;
3841 #ifdef FUNCTION_ARG_CALLEE_COPIES
3844 #endif
3845 ;
3847 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3848 functions, so we have to pretend this isn't such a function. */
3850 {
3854 }
3857 /* If this was a CONST function, it is now PURE since
3858 it now reads memory. */
3860 {
3863 }
3868 {
3872 }
3873 else
3874 {
3877 slot
3883 }
3887 call_fusage);
3891 slot),
3892 call_fusage);
3896 }
3897 #endif
3904 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3907 #else
3909 #endif
3912 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3914 #else
3916 #endif
3928 }
3930 #ifdef FINAL_REG_PARM_STACK_SPACE
3933 #endif
3934 /* If this machine requires an external definition for library
3935 functions, write one out. */
3940 + stack_pointer_delta
3942 / STACK_BYTES
3947 reg_parm_stack_space);
3949 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3951 #endif
3957 {
3958 /* Since the stack pointer will never be pushed, it is possible for
3959 the evaluation of a parm to clobber something we have already
3960 written to the stack. Since most function calls on RISC machines
3961 do not use the stack, this is uncommon, but must work correctly.
3963 Therefore, we save any area of the stack that was already written
3964 and that we are using. Here we set up to do this by making a new
3965 stack usage map from the old one.
3967 Another approach might be to try to reorder the argument
3968 evaluations to avoid this conflicting stack usage. */
3972 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3973 /* Since we will be writing into the entire argument area, the
3974 map must be allocated for its entire size, not just the part that
3975 is the responsibility of the caller. */
3977 #endif
3979 #ifdef ARGS_GROW_DOWNWARD
3982 #else
3984 needed);
3985 #endif
3990 initial_highest_arg_in_use);
3997 /* We must be careful to use virtual regs before they're instantiated,
3998 and real regs afterwards. Loop optimization, for example, can create
3999 new libcalls after we've instantiated the virtual regs, and if we
4000 use virtuals anyway, they won't match the rtl patterns. */
4004 else
4006 }
4007 else
4008 {
4011 }
4013 /* If we push args individually in reverse order, perform stack alignment
4014 before the first push (the last arg). */
4020 {
4023 }
4024 else
4025 {
4028 }
4030 #ifdef REG_PARM_STACK_SPACE
4032 {
4033 /* The argument list is the property of the called routine and it
4034 may clobber it. If the fixed area has been used for previous
4035 parameters, we must save and restore it. */
4038 }
4039 #endif
4041 /* Push the args that need to be pushed. */
4043 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4044 are to be pushed. */
4046 {
4054 {
4056 {
4057 /* If this is being stored into a pre-allocated, fixed-size,
4058 stack area, save any previous data at that location. */
4060 #ifdef ARGS_GROW_DOWNWARD
4061 /* stack_slot is negative, but we want to index stack_usage_map
4062 with positive values. */
4065 #else
4068 #endif
4071 /* Don't worry about things in the fixed argument area;
4072 it has already been saved. */
4076 i++;
4079 {
4080 /* We need to make a save area. */
4081 unsigned int size
4083 enum machine_mode save_mode
4085 rtx adr
4088 rtx stack_area
4092 {
4099 stack_area,
4101 BLOCK_OP_CALL_PARM);
4102 }
4103 else
4104 {
4108 }
4109 }
4110 }
4115 reg_parm_stack_space,
4118 /* Now mark the segment we just used. */
4123 NO_DEFER_POP;
4124 }
4125 }
4127 /* If we pushed args in forward order, perform stack alignment
4128 after pushing the last arg. */
4135 else
4140 /* Now load any reg parms into their regs. */
4142 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4143 are to be pushed. */
4145 {
4150 /* Handle calls that pass values in multiple non-contiguous
4151 locations. The PA64 has examples of this for library calls. */
4157 NO_DEFER_POP;
4158 }
4160 /* Any regs containing parms remain in use through the call. */
4162 {
4168 }
4170 /* Pass the function the address in which to return a structure value. */
4172 {
4176 NULL_RTX)));
4179 }
4181 /* Don't allow popping to be deferred, since then
4182 cse'ing of library calls could delete a call and leave the pop. */
4183 NO_DEFER_POP;
4187 /* Stack must be properly aligned now. */
4193 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4194 will set inhibit_defer_pop to that value. */
4195 /* The return type is needed to decide how many bytes the function pops.
4196 Signedness plays no role in that, so for simplicity, we pretend it's
4197 always signed. We also assume that the list of arguments passed has
4198 no impact, so we pretend it is unknown. */
4204 struct_value_size,
4206 valreg,
4209 /* For calls to `setjmp', etc., inform flow.c it should complain
4210 if nonvolatile values are live. For functions that cannot return,
4211 inform flow that control does not fall through. */
4214 {
4215 /* The barrier note must be emitted
4216 immediately after the CALL_INSN. Some ports emit more than
4217 just a CALL_INSN above, so we must search for it here. */
4221 {
4223 /* There was no CALL_INSN? */
4226 }
4229 }
4231 /* Now restore inhibit_defer_pop to its actual original value. */
4232 OK_DEFER_POP;
4234 /* If call is cse'able, make appropriate pair of reg-notes around it.
4235 Test valreg so we don't crash; may safely ignore `const'
4236 if return type is void. Disable for PARALLEL return values, because
4237 we have no way to move such values into a pseudo register. */
4239 {
4240 rtx insns;
4243 {
4247 }
4248 else
4249 {
4251 rtx temp;
4255 {
4260 }
4264 /* Construct an "equal form" for the value which mentions all the
4265 arguments in order as well as the function name. */
4278 note);
4283 }
4284 }
4287 /* Copy the value to the right place. */
4289 {
4291 {
4296 }
4298 {
4302 }
4305 else
4307 }
4310 {
4311 #ifdef REG_PARM_STACK_SPACE
4315 #endif
4317 /* If we saved any argument areas, restore them. */
4320 {
4331 BLOCK_OP_CALL_PARM);
4332 else
4334 }
4338 }
4342 }
4343 \f
4344 /* Output a library call to function FUN (a SYMBOL_REF rtx)
4345 (emitting the queue unless NO_QUEUE is nonzero),
4346 for a value of mode OUTMODE,
4347 with NARGS different arguments, passed as alternating rtx values
4348 and machine_modes to convert them to.
4349 The rtx values should have been passed through protect_from_queue already.
4351 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
4352 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
4353 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
4354 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
4355 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
4356 or other LCT_ value for other types of library calls. */
4358 void
4361 {
4367 }
4368 \f
4369 /* Like emit_library_call except that an extra argument, VALUE,
4370 comes second and says where to store the result.
4371 (If VALUE is zero, this function chooses a convenient way
4372 to return the value.
4374 This function returns an rtx for where the value is to be found.
4375 If VALUE is nonzero, VALUE is returned. */
4377 rtx
4381 {
4382 rtx result;
4391 }
4392 \f
4393 /* Store a single argument for a function call
4394 into the register or memory area where it must be passed.
4395 *ARG describes the argument value and where to pass it.
4397 ARGBLOCK is the address of the stack-block for all the arguments,
4398 or 0 on a machine where arguments are pushed individually.
4400 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4401 so must be careful about how the stack is used.
4403 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4404 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4405 that we need not worry about saving and restoring the stack.
4407 FNDECL is the declaration of the function we are calling.
4409 Return nonzero if this arg should cause sibcall failure,
4410 zero otherwise. */
4412 static int
4415 {
4426 /* Push a new temporary level for any temporaries we make for
4427 this argument. */
4431 {
4432 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4433 save any previous data at that location. */
4435 {
4436 #ifdef ARGS_GROW_DOWNWARD
4437 /* stack_slot is negative, but we want to index stack_usage_map
4438 with positive values. */
4441 else
4445 #else
4448 else
4452 #endif
4455 /* Don't worry about things in the fixed argument area;
4456 it has already been saved. */
4460 i++;
4463 {
4464 /* We need to make a save area. */
4471 {
4480 BLOCK_OP_CALL_PARM);
4481 }
4482 else
4483 {
4486 }
4487 }
4488 }
4489 }
4491 /* If this isn't going to be placed on both the stack and in registers,
4492 set up the register and number of words. */
4494 {
4497 else
4500 }
4503 /* Being passed entirely in a register. We shouldn't be called in
4504 this case. */
4507 /* If this arg needs special alignment, don't load the registers
4508 here. */
4512 /* If this is being passed partially in a register, we can't evaluate
4513 it directly into its stack slot. Otherwise, we can. */
4515 {
4516 /* stack_arg_under_construction is nonzero if a function argument is
4517 being evaluated directly into the outgoing argument list and
4518 expand_call must take special action to preserve the argument list
4519 if it is called recursively.
4521 For scalar function arguments stack_usage_map is sufficient to
4522 determine which stack slots must be saved and restored. Scalar
4523 arguments in general have pass_on_stack == 0.
4525 If this argument is initialized by a function which takes the
4526 address of the argument (a C++ constructor or a C function
4527 returning a BLKmode structure), then stack_usage_map is
4528 insufficient and expand_call must push the stack around the
4529 function call. Such arguments have pass_on_stack == 1.
4531 Note that it is always safe to set stack_arg_under_construction,
4532 but this generates suboptimal code if set when not needed. */
4535 stack_arg_under_construction++;
4538 (partial
4543 /* If we are promoting object (or for any other reason) the mode
4544 doesn't agree, convert the mode. */
4551 stack_arg_under_construction--;
4552 }
4554 /* Don't allow anything left on stack from computation
4555 of argument to alloca. */
4560 /* If the value is already in the stack slot, we are done. */
4561 ;
4563 {
4566 /* Argument is a scalar, not entirely passed in registers.
4567 (If part is passed in registers, arg->partial says how much
4568 and emit_push_insn will take care of putting it there.)
4570 Push it, and if its size is less than the
4571 amount of space allocated to it,
4572 also bump stack pointer by the additional space.
4573 Note that in C the default argument promotions
4574 will prevent such mismatches. */
4577 /* Compute how much space the push instruction will push.
4578 On many machines, pushing a byte will advance the stack
4579 pointer by a halfword. */
4580 #ifdef PUSH_ROUNDING
4582 #endif
4585 /* Compute how much space the argument should get:
4586 round up to a multiple of the alignment for arguments. */
4592 /* This isn't already where we want it on the stack, so put it there.
4593 This can either be done with push or copy insns. */
4599 /* Unless this is a partially-in-register argument, the argument is now
4600 in the stack. */
4603 }
4604 else
4605 {
4606 /* BLKmode, at least partly to be pushed. */
4610 rtx size_rtx;
4612 /* Pushing a nonscalar.
4613 If part is passed in registers, PARTIAL says how much
4614 and emit_push_insn will take care of putting it there. */
4616 /* Round its size up to a multiple
4617 of the allocation unit for arguments. */
4620 {
4623 }
4624 else
4625 {
4626 /* PUSH_ROUNDING has no effect on us, because
4627 emit_push_insn for BLKmode is careful to avoid it. */
4629 {
4630 /* Use the size of the elt to compute excess. */
4635 }
4636 else
4642 }
4644 /* Some types will require stricter alignment, which will be
4645 provided for elsewhere in argument layout. */
4648 /* When an argument is padded down, the block is aligned to
4649 PARM_BOUNDARY, but the actual argument isn't. */
4651 {
4655 {
4658 }
4659 }
4662 {
4663 /* emit_push_insn might not work properly if arg->value and
4664 argblock + arg->locate.offset areas overlap. */
4671 current_function_internal_arg_pointer
4673 {
4677 /* expand_call should ensure this */
4682 {
4685 }
4687 {
4690 }
4691 }
4692 }
4699 /* Unless this is a partially-in-register argument, the argument is now
4700 in the stack.
4702 ??? Unlike the case above, in which we want the actual
4703 address of the data, so that we can load it directly into a
4704 register, here we want the address of the stack slot, so that
4705 it's properly aligned for word-by-word copying or something
4706 like that. It's not clear that this is always correct. */
4709 }
4711 /* Mark all slots this store used. */
4717 /* Once we have pushed something, pops can't safely
4718 be deferred during the rest of the arguments. */
4719 NO_DEFER_POP;
4721 /* ANSI doesn't require a sequence point here,
4722 but PCC has one, so this will avoid some problems. */
4725 /* Free any temporary slots made in processing this argument. Show
4726 that we might have taken the address of something and pushed that
4727 as an operand. */
4733 }
4735 /* Nonzero if we do not know how to pass TYPE solely in registers.
4736 We cannot do so in the following cases:
4738 - if the type has variable size
4739 - if the type is marked as addressable (it is required to be constructed
4740 into the stack)
4741 - if the padding and mode of the type is such that a copy into a register
4742 would put it into the wrong part of the register.
4744 Which padding can't be supported depends on the byte endianness.
4746 A value in a register is implicitly padded at the most significant end.
4747 On a big-endian machine, that is the lower end in memory.
4748 So a value padded in memory at the upper end can't go in a register.
4749 For a little-endian machine, the reverse is true. */
4751 bool
4753 {
4757 /* If the type has variable size... */
4761 /* If the type is marked as addressable (it is required
4762 to be constructed into the stack)... */
4766 /* If the padding and mode of the type is such that a copy into
4767 a register would put it into the wrong part of the register. */
4775 }