| blob | 99722b5da2e356a4a8461282f0ba084a7abe0af3 |
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 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. */
39 #if !defined FUNCTION_OK_FOR_SIBCALL
40 #define FUNCTION_OK_FOR_SIBCALL(DECL) 1
41 #endif
43 /* Decide whether a function's arguments should be processed
44 from first to last or from last to first.
46 They should if the stack and args grow in opposite directions, but
47 only if we have push insns. */
49 #ifdef PUSH_ROUNDING
51 #ifndef PUSH_ARGS_REVERSED
52 #if defined (STACK_GROWS_DOWNWARD) != defined (ARGS_GROW_DOWNWARD)
53 #define PUSH_ARGS_REVERSED PUSH_ARGS
54 #endif
55 #endif
57 #endif
59 #ifndef PUSH_ARGS_REVERSED
60 #define PUSH_ARGS_REVERSED 0
61 #endif
63 #ifndef STACK_POINTER_OFFSET
64 #define STACK_POINTER_OFFSET 0
65 #endif
67 /* Like PREFERRED_STACK_BOUNDARY but in units of bytes, not bits. */
68 #define STACK_BYTES (PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT)
70 /* Data structure and subroutines used within expand_call. */
72 struct arg_data
73 {
74 /* Tree node for this argument. */
75 tree tree_value;
76 /* Mode for value; TYPE_MODE unless promoted. */
78 /* Current RTL value for argument, or 0 if it isn't precomputed. */
79 rtx value;
80 /* Initially-compute RTL value for argument; only for const functions. */
81 rtx initial_value;
82 /* Register to pass this argument in, 0 if passed on stack, or an
83 PARALLEL if the arg is to be copied into multiple non-contiguous
84 registers. */
85 rtx reg;
86 /* Register to pass this argument in when generating tail call sequence.
87 This is not the same register as for normal calls on machines with
88 register windows. */
89 rtx tail_call_reg;
90 /* If REG was promoted from the actual mode of the argument expression,
91 indicates whether the promotion is sign- or zero-extended. */
93 /* Number of registers to use. 0 means put the whole arg in registers.
94 Also 0 if not passed in registers. */
96 /* Nonzero if argument must be passed on stack.
97 Note that some arguments may be passed on the stack
98 even though pass_on_stack is zero, just because FUNCTION_ARG says so.
99 pass_on_stack identifies arguments that *cannot* go in registers. */
101 /* Offset of this argument from beginning of stack-args. */
103 /* Similar, but offset to the start of the stack slot. Different from
104 OFFSET if this arg pads downward. */
106 /* Size of this argument on the stack, rounded up for any padding it gets,
107 parts of the argument passed in registers do not count.
108 If REG_PARM_STACK_SPACE is defined, then register parms
109 are counted here as well. */
111 /* Location on the stack at which parameter should be stored. The store
112 has already been done if STACK == VALUE. */
113 rtx stack;
114 /* Location on the stack of the start of this argument slot. This can
115 differ from STACK if this arg pads downward. This location is known
116 to be aligned to FUNCTION_ARG_BOUNDARY. */
117 rtx stack_slot;
118 /* Place that this stack area has been saved, if needed. */
119 rtx save_area;
120 /* If an argument's alignment does not permit direct copying into registers,
121 copy in smaller-sized pieces into pseudos. These are stored in a
122 block pointed to by this field. The next field says how many
123 word-sized pseudos we made. */
126 /* The amount that the stack pointer needs to be adjusted to
127 force alignment for the next argument. */
129 };
131 /* A vector of one char per byte of stack space. A byte if nonzero if
132 the corresponding stack location has been used.
133 This vector is used to prevent a function call within an argument from
134 clobbering any stack already set up. */
137 /* Size of STACK_USAGE_MAP. */
140 /* A bitmap of virtual-incoming stack space. Bit is set if the corresponding
141 stack location's tail call argument has been already stored into the stack.
142 This bitmap is used to prevent sibling call optimization if function tries
143 to use parent's incoming argument slots when they have been already
144 overwritten with tail call arguments. */
147 /* stack_arg_under_construction is nonzero when an argument may be
148 initialized with a constructor call (including a C function that
149 returns a BLKmode struct) and expand_call must take special action
150 to make sure the object being constructed does not overlap the
151 argument list for the constructor call. */
157 /* Nonzero if this is a call to a `const' function. */
158 #define ECF_CONST 1
159 /* Nonzero if this is a call to a `volatile' function. */
160 #define ECF_NORETURN 2
161 /* Nonzero if this is a call to malloc or a related function. */
162 #define ECF_MALLOC 4
163 /* Nonzero if it is plausible that this is a call to alloca. */
164 #define ECF_MAY_BE_ALLOCA 8
165 /* Nonzero if this is a call to a function that won't throw an exception. */
166 #define ECF_NOTHROW 16
167 /* Nonzero if this is a call to setjmp or a related function. */
168 #define ECF_RETURNS_TWICE 32
169 /* Nonzero if this is a call to `longjmp'. */
170 #define ECF_LONGJMP 64
171 /* Nonzero if this is a syscall that makes a new process in the image of
172 the current one. */
173 #define ECF_FORK_OR_EXEC 128
174 #define ECF_SIBCALL 256
175 /* Nonzero if this is a call to "pure" function (like const function,
176 but may read memory. */
177 #define ECF_PURE 512
178 /* Nonzero if this is a call to a function that returns with the stack
179 pointer depressed. */
180 #define ECF_SP_DEPRESSED 1024
181 /* Nonzero if this call is known to always return. */
182 #define ECF_ALWAYS_RETURN 2048
183 /* Create libcall block around the call. */
184 #define ECF_LIBCALL_BLOCK 4096
189 CUMULATIVE_ARGS *));
209 CUMULATIVE_ARGS *,
228 static int combine_pending_stack_adjustment_and_call
231 #ifdef REG_PARM_STACK_SPACE
234 #endif
235 \f
236 /* If WHICH is 1, return 1 if EXP contains a call to the built-in function
237 `alloca'.
239 If WHICH is 0, return 1 if EXP contains a call to any function.
240 Actually, we only need return 1 if evaluating EXP would require pushing
241 arguments on the stack, but that is too difficult to compute, so we just
242 assume any function call might require the stack. */
246 static int
248 tree exp;
250 {
257 }
259 /* Recursive function to do the work of above function. */
261 static int
263 tree exp;
265 {
271 /* If this code is language-specific, we don't know what it will do. */
276 {
282 && (TYPE_RETURNS_STACK_DEPRESSED
296 {
297 tree tem;
302 }
312 calls_function_save_exprs);
317 {
318 tree local;
319 tree subblock;
327 subblock;
331 }
342 }
344 /* Only expressions, references, and blocks can contain calls. */
354 }
355 \f
356 /* Force FUNEXP into a form suitable for the address of a CALL,
357 and return that as an rtx. Also load the static chain register
358 if FNDECL is a nested function.
360 CALL_FUSAGE points to a variable holding the prospective
361 CALL_INSN_FUNCTION_USAGE information. */
363 rtx
365 rtx funexp;
366 tree fndecl;
370 {
376 /* Get possible static chain value for nested function in C. */
379 /* Make a valid memory address and copy constants thru pseudo-regs,
380 but not for a constant address if -fno-function-cse. */
382 /* If we are using registers for parameters, force the
383 function address into a register now. */
388 {
389 #ifndef NO_FUNCTION_CSE
391 #ifdef NO_RECURSIVE_FUNCTION_CSE
393 #endif
395 #endif
396 }
399 {
404 }
407 }
409 /* Generate instructions to call function FUNEXP,
410 and optionally pop the results.
411 The CALL_INSN is the first insn generated.
413 FNDECL is the declaration node of the function. This is given to the
414 macro RETURN_POPS_ARGS to determine whether this function pops its own args.
416 FUNTYPE is the data type of the function. This is given to the macro
417 RETURN_POPS_ARGS to determine whether this function pops its own args.
418 We used to allow an identifier for library functions, but that doesn't
419 work when the return type is an aggregate type and the calling convention
420 says that the pointer to this aggregate is to be popped by the callee.
422 STACK_SIZE is the number of bytes of arguments on the stack,
423 ROUNDED_STACK_SIZE is that number rounded up to
424 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
425 both to put into the call insn and to generate explicit popping
426 code if necessary.
428 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
429 It is zero if this call doesn't want a structure value.
431 NEXT_ARG_REG is the rtx that results from executing
432 FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1)
433 just after all the args have had their registers assigned.
434 This could be whatever you like, but normally it is the first
435 arg-register beyond those used for args in this call,
436 or 0 if all the arg-registers are used in this call.
437 It is passed on to `gen_call' so you can put this info in the call insn.
439 VALREG is a hard register in which a value is returned,
440 or 0 if the call does not return a value.
442 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
443 the args to this call were processed.
444 We restore `inhibit_defer_pop' to that value.
446 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
447 denote registers used by the called function. */
449 static void
453 rtx funexp;
454 tree fndecl ATTRIBUTE_UNUSED;
455 tree funtype ATTRIBUTE_UNUSED;
456 HOST_WIDE_INT stack_size ATTRIBUTE_UNUSED;
457 HOST_WIDE_INT rounded_stack_size;
458 HOST_WIDE_INT struct_value_size ATTRIBUTE_UNUSED;
459 rtx next_arg_reg ATTRIBUTE_UNUSED;
460 rtx valreg;
462 rtx call_fusage;
465 {
467 rtx call_insn;
470 #if defined (HAVE_call) && defined (HAVE_call_value)
471 rtx struct_value_size_rtx;
473 #endif
475 #ifdef CALL_POPS_ARGS
477 #endif
479 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
480 and we don't want to load it into a register as an optimization,
481 because prepare_call_address already did it if it should be done. */
485 #if defined (HAVE_sibcall_pop) && defined (HAVE_sibcall_value_pop)
489 {
491 rtx pat;
493 /* If this subroutine pops its own args, record that in the call insn
494 if possible, for the sake of frame pointer elimination. */
500 n_pop);
501 else
507 }
508 else
509 #endif
511 #if defined (HAVE_call_pop) && defined (HAVE_call_value_pop)
512 /* If the target has "call" or "call_value" insns, then prefer them
513 if no arguments are actually popped. If the target does not have
514 "call" or "call_value" insns, then we must use the popping versions
515 even if the call has no arguments to pop. */
516 #if defined (HAVE_call) && defined (HAVE_call_value)
519 #else
521 #endif
522 {
524 rtx pat;
526 /* If this subroutine pops its own args, record that in the call insn
527 if possible, for the sake of frame pointer elimination. */
533 else
539 }
540 else
541 #endif
543 #if defined (HAVE_sibcall) && defined (HAVE_sibcall_value)
546 {
550 rounded_stack_size_rtx,
552 else
555 struct_value_size_rtx));
556 }
557 else
558 #endif
560 #if defined (HAVE_call) && defined (HAVE_call_value)
562 {
567 NULL_RTX));
568 else
571 struct_value_size_rtx));
572 }
573 else
574 #endif
577 /* Find the CALL insn we just emitted. */
581 ;
586 /* Mark memory as used for "pure" function call. */
588 call_fusage
589 = gen_rtx_EXPR_LIST
593 call_fusage);
595 /* Put the register usage information on the CALL. If there is already
596 some usage information, put ours at the end. */
598 {
599 rtx link;
603 ;
606 }
607 else
610 /* If this is a const call, then set the insn's unchanging bit. */
614 /* If this call can't throw, attach a REG_EH_REGION reg note to that
615 effect. */
628 {
632 }
636 /* Restore this now, so that we do defer pops for this call's args
637 if the context of the call as a whole permits. */
641 {
650 }
653 {
654 /* If returning from the subroutine does not automatically pop the args,
655 we need an instruction to pop them sooner or later.
656 Perhaps do it now; perhaps just record how much space to pop later.
658 If returning from the subroutine does pop the args, indicate that the
659 stack pointer will be changed. */
662 {
664 /* Just pretend we did the pop. */
669 else
671 }
672 }
673 /* When we accumulate outgoing args, we must avoid any stack manipulations.
674 Restore the stack pointer to its original value now. Usually
675 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
676 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
677 popping variants of functions exist as well.
679 ??? We may optimize similar to defer_pop above, but it is
680 probably not worthwhile.
682 ??? It will be worthwhile to enable combine_stack_adjustments even for
683 such machines. */
686 }
688 /* Determine if the function identified by NAME and FNDECL is one with
689 special properties we wish to know about.
691 For example, if the function might return more than one time (setjmp), then
692 set RETURNS_TWICE to a nonzero value.
694 Similarly set LONGJMP for if the function is in the longjmp family.
696 Set MALLOC for any of the standard memory allocation functions which
697 allocate from the heap.
699 Set MAY_BE_ALLOCA for any memory allocation function that might allocate
700 space from the stack such as alloca. */
702 static int
704 tree fndecl;
706 {
710 /* Exclude functions not at the file scope, or not `extern',
711 since they are not the magic functions we would otherwise
712 think they are. */
714 {
718 /* We assume that alloca will always be called by name. It
719 makes no sense to pass it as a pointer-to-function to
720 anything that does not understand its behavior. */
729 /* Disregard prefix _, __ or __x. */
731 {
736 else
738 }
741 {
754 }
767 /* Linux specific: __clone. check NAME to insist on the
768 leading underscores, to avoid polluting the ISO / POSIX
769 namespace. */
779 /* Do not add any more malloc-like functions to this list,
780 instead mark them as malloc functions using the malloc attribute.
781 Note, realloc is not suitable for attribute malloc since
782 it may return the same address across multiple calls.
783 C++ operator new is not suitable because it is not required
784 to return a unique pointer; indeed, the standard placement new
785 just returns its argument. */
791 }
793 }
795 /* Return nonzero when tree represent call to longjmp. */
797 int
799 tree fndecl;
800 {
802 }
804 /* Return true when exp contains alloca call. */
805 bool
807 tree exp;
808 {
817 }
819 /* Detect flags (function attributes) from the function decl or type node. */
821 static int
823 tree exp;
824 {
827 /* ??? We can't set IS_MALLOC for function types? */
829 {
832 /* The function exp may have the `malloc' attribute. */
836 /* The function exp may have the `pure' attribute. */
842 }
850 /* Mark if the function returns with the stack pointer depressed. We
851 cannot consider it pure or constant in that case. */
853 {
856 }
859 }
861 /* Precompute all register parameters as described by ARGS, storing values
862 into fields within the ARGS array.
864 NUM_ACTUALS indicates the total number elements in the ARGS array.
866 Set REG_PARM_SEEN if we encounter a register parameter. */
868 static void
873 {
880 {
884 {
891 /* ANSI doesn't require a sequence point here,
892 but PCC has one, so this will avoid some problems. */
894 }
896 /* If the value is a non-legitimate constant, force it into a
897 pseudo now. TLS symbols sometimes need a call to resolve. */
902 /* If we are to promote the function arg to a wider mode,
903 do it now. */
911 /* If the value is expensive, and we are inside an appropriately
912 short loop, put the value into a pseudo and then put the pseudo
913 into the hard reg.
915 For small register classes, also do this if this call uses
916 register parameters. This is to avoid reload conflicts while
917 loading the parameters registers. */
927 }
928 }
930 #ifdef REG_PARM_STACK_SPACE
932 /* The argument list is the property of the called routine and it
933 may clobber it. If the fixed area has been used for previous
934 parameters, we must save and restore it. */
936 static rtx
940 rtx argblock;
943 {
947 /* Compute the boundary of the that needs to be saved, if any. */
948 #ifdef ARGS_GROW_DOWNWARD
950 #else
952 #endif
953 {
962 }
965 {
967 enum machine_mode save_mode
969 rtx stack_area;
971 /* If we don't have the required alignment, must do this in BLKmode. */
976 #ifdef ARGS_GROW_DOWNWARD
977 stack_area
982 #else
987 #endif
991 {
995 }
996 else
997 {
1000 }
1001 }
1004 }
1006 static void
1008 rtx save_area;
1009 rtx argblock;
1012 {
1014 #ifdef ARGS_GROW_DOWNWARD
1015 rtx stack_area
1020 #else
1021 rtx stack_area
1025 low_to_save)));
1026 #endif
1030 else
1033 BLOCK_OP_CALL_PARM);
1034 }
1037 /* If any elements in ARGS refer to parameters that are to be passed in
1038 registers, but not in memory, and whose alignment does not permit a
1039 direct copy into registers. Copy the values into a group of pseudos
1040 which we will later copy into the appropriate hard registers.
1042 Pseudos for each unaligned argument will be stored into the array
1043 args[argnum].aligned_regs. The caller is responsible for deallocating
1044 the aligned_regs array if it is nonzero. */
1046 static void
1050 {
1058 {
1069 /* Structures smaller than a word are aligned to the least
1070 significant byte (to the right). On a BYTES_BIG_ENDIAN machine,
1071 this means we must skip the empty high order bytes when
1072 calculating the bit offset. */
1074 && !FUNCTION_ARG_REG_LITTLE_ENDIAN
1079 {
1086 /* There is no need to restrict this code to loading items
1087 in TYPE_ALIGN sized hunks. The bitfield instructions can
1088 load up entire word sized registers efficiently.
1090 ??? This may not be needed anymore.
1091 We use to emit a clobber here but that doesn't let later
1092 passes optimize the instructions we emit. By storing 0 into
1093 the register later passes know the first AND to zero out the
1094 bitfield being set in the register is unnecessary. The store
1095 of 0 will be deleted as will at least the first AND. */
1103 BITS_PER_WORD),
1104 BITS_PER_WORD);
1105 }
1106 }
1107 }
1109 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
1110 ACTPARMS.
1112 NUM_ACTUALS is the total number of parameters.
1114 N_NAMED_ARGS is the total number of named arguments.
1116 FNDECL is the tree code for the target of this call (if known)
1118 ARGS_SO_FAR holds state needed by the target to know where to place
1119 the next argument.
1121 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
1122 for arguments which are passed in registers.
1124 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
1125 and may be modified by this routine.
1127 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
1128 flags which may may be modified by this routine. */
1130 static void
1135 ecf_flags)
1140 tree actparms;
1141 tree fndecl;
1148 {
1149 /* 1 if scanning parms front to back, -1 if scanning back to front. */
1152 /* Count arg position in order args appear. */
1157 tree p;
1162 /* In this loop, we consider args in the order they are written.
1163 We fill up ARGS from the front or from the back if necessary
1164 so that in any case the first arg to be pushed ends up at the front. */
1167 {
1169 /* In this case, must reverse order of args
1170 so that we compute and push the last arg first. */
1171 }
1172 else
1173 {
1175 }
1177 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1179 {
1186 /* Replace erroneous argument with constant zero. */
1190 /* If TYPE is a transparent union, pass things the way we would
1191 pass the first field of the union. We have already verified that
1192 the modes are the same. */
1196 /* Decide where to pass this arg.
1198 args[i].reg is nonzero if all or part is passed in registers.
1200 args[i].partial is nonzero if part but not all is passed in registers,
1201 and the exact value says how many words are passed in registers.
1203 args[i].pass_on_stack is nonzero if the argument must at least be
1204 computed on the stack. It may then be loaded back into registers
1205 if args[i].reg is nonzero.
1207 These decisions are driven by the FUNCTION_... macros and must agree
1208 with those made by function.c. */
1210 /* See if this argument should be passed by invisible reference. */
1214 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
1217 #endif
1218 )
1219 {
1220 /* If we're compiling a thunk, pass through invisible
1221 references instead of making a copy. */
1223 #ifdef FUNCTION_ARG_CALLEE_COPIES
1226 /* If it's in a register, we must make a copy of it too. */
1227 /* ??? Is this a sufficient test? Is there a better one? */
1231 #endif
1232 )
1233 {
1234 /* C++ uses a TARGET_EXPR to indicate that we want to make a
1235 new object from the argument. If we are passing by
1236 invisible reference, the callee will do that for us, so we
1237 can strip off the TARGET_EXPR. This is not always safe,
1238 but it is safe in the only case where this is a useful
1239 optimization; namely, when the argument is a plain object.
1240 In that case, the frontend is just asking the backend to
1241 make a bitwise copy of the argument. */
1252 }
1254 {
1255 /* In the V3 C++ ABI, parameters are destroyed in the caller.
1256 We implement this by passing the address of the temporary
1257 rather than expanding it into another allocated slot. */
1262 }
1263 else
1264 {
1265 /* We make a copy of the object and pass the address to the
1266 function being called. */
1267 rtx copy;
1273 STACK_CHECK_MAX_VAR_SIZE))))
1274 {
1275 /* This is a variable-sized object. Make space on the stack
1276 for it. */
1280 {
1284 }
1287 allocate_dynamic_stack_space
1290 }
1291 else
1301 }
1302 }
1307 #ifdef PROMOTE_FUNCTION_ARGS
1309 #endif
1316 #ifdef FUNCTION_INCOMING_ARG
1317 /* If this is a sibling call and the machine has register windows, the
1318 register window has to be unwinded before calling the routine, so
1319 arguments have to go into the incoming registers. */
1322 #else
1324 #endif
1326 #ifdef FUNCTION_ARG_PARTIAL_NREGS
1331 #endif
1335 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1336 it means that we are to pass this arg in the register(s) designated
1337 by the PARALLEL, but also to pass it in the stack. */
1342 /* If this is an addressable type, we must preallocate the stack
1343 since we must evaluate the object into its final location.
1345 If this is to be passed in both registers and the stack, it is simpler
1346 to preallocate. */
1351 /* If this is an addressable type, we cannot pre-evaluate it. Thus,
1352 we cannot consider this function call constant. */
1356 /* Compute the stack-size of this argument. */
1361 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1363 #else
1365 #endif
1369 #ifndef ARGS_GROW_DOWNWARD
1371 #endif
1375 /* If a part of the arg was put into registers,
1376 don't include that part in the amount pushed. */
1382 /* Update ARGS_SIZE, the total stack space for args so far. */
1386 {
1388 }
1390 /* Since the slot offset points to the bottom of the slot,
1391 we must record it after incrementing if the args grow down. */
1392 #ifdef ARGS_GROW_DOWNWARD
1398 #endif
1400 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1401 have been used, etc. */
1405 }
1406 }
1408 /* Update ARGS_SIZE to contain the total size for the argument block.
1409 Return the original constant component of the argument block's size.
1411 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1412 for arguments passed in registers. */
1414 static int
1416 preferred_stack_boundary)
1420 {
1423 /* For accumulate outgoing args mode we don't need to align, since the frame
1424 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1425 backends from generating misaligned frame sizes. */
1429 /* Compute the actual size of the argument block required. The variable
1430 and constant sizes must be combined, the size may have to be rounded,
1431 and there may be a minimum required size. */
1434 {
1440 {
1441 /* We don't handle this case yet. To handle it correctly we have
1442 to add the delta, round and subtract the delta.
1443 Currently no machine description requires this support. */
1447 }
1450 {
1451 args_size->var
1455 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1456 /* The area corresponding to register parameters is not to count in
1457 the size of the block we need. So make the adjustment. */
1458 args_size->var
1461 #endif
1462 }
1463 }
1464 else
1465 {
1470 + stack_pointer_delta
1472 / preferred_stack_boundary
1477 reg_parm_stack_space);
1479 #ifdef MAYBE_REG_PARM_STACK_SPACE
1482 #endif
1484 #ifndef OUTGOING_REG_PARM_STACK_SPACE
1486 #endif
1487 }
1489 }
1491 /* Precompute parameters as needed for a function call.
1493 FLAGS is mask of ECF_* constants.
1495 NUM_ACTUALS is the number of arguments.
1497 ARGS is an array containing information for each argument; this
1498 routine fills in the INITIAL_VALUE and VALUE fields for each
1499 precomputed argument. */
1501 static void
1506 {
1509 /* If this function call is cse'able, precompute all the parameters.
1510 Note that if the parameter is constructed into a temporary, this will
1511 cause an additional copy because the parameter will be constructed
1512 into a temporary location and then copied into the outgoing arguments.
1513 If a parameter contains a call to alloca and this function uses the
1514 stack, precompute the parameter. */
1516 /* If we preallocated the stack space, and some arguments must be passed
1517 on the stack, then we must precompute any parameter which contains a
1518 function call which will store arguments on the stack.
1519 Otherwise, evaluating the parameter may clobber previous parameters
1520 which have already been stored into the stack. (we have code to avoid
1521 such case by saving the outgoing stack arguments, but it results in
1522 worse code) */
1527 {
1530 /* If this is an addressable type, we cannot pre-evaluate it. */
1537 /* ANSI doesn't require a sequence point here,
1538 but PCC has one, so this will avoid some problems. */
1546 {
1550 #ifdef PROMOTE_FOR_CALL_ONLY
1551 /* CSE will replace this only if it contains args[i].value
1552 pseudo, so convert it down to the declared mode using
1553 a SUBREG. */
1556 {
1562 }
1563 #endif
1564 }
1565 }
1566 }
1568 /* Given the current state of MUST_PREALLOCATE and information about
1569 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1570 compute and return the final value for MUST_PREALLOCATE. */
1572 static int
1578 {
1579 /* See if we have or want to preallocate stack space.
1581 If we would have to push a partially-in-regs parm
1582 before other stack parms, preallocate stack space instead.
1584 If the size of some parm is not a multiple of the required stack
1585 alignment, we must preallocate.
1587 If the total size of arguments that would otherwise create a copy in
1588 a temporary (such as a CALL) is more than half the total argument list
1589 size, preallocation is faster.
1591 Another reason to preallocate is if we have a machine (like the m88k)
1592 where stack alignment is required to be maintained between every
1593 pair of insns, not just when the call is made. However, we assume here
1594 that such machines either do not have push insns (and hence preallocation
1595 would occur anyway) or the problem is taken care of with
1596 PUSH_ROUNDING. */
1599 {
1605 {
1616 copy_to_evaluate_size
1618 }
1623 }
1625 }
1627 /* If we preallocated stack space, compute the address of each argument
1628 and store it into the ARGS array.
1630 We need not ensure it is a valid memory address here; it will be
1631 validized when it is used.
1633 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1635 static void
1638 rtx argblock;
1640 {
1642 {
1650 {
1653 rtx addr;
1655 /* Skip this parm if it will not be passed on the stack. */
1661 else
1671 else
1679 /* Function incoming arguments may overlap with sibling call
1680 outgoing arguments and we cannot allow reordering of reads
1681 from function arguments with stores to outgoing arguments
1682 of sibling calls. */
1685 }
1686 }
1687 }
1689 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1690 in a call instruction.
1692 FNDECL is the tree node for the target function. For an indirect call
1693 FNDECL will be NULL_TREE.
1695 EXP is the CALL_EXPR for this call. */
1697 static rtx
1699 tree fndecl;
1700 tree exp;
1701 {
1702 rtx funexp;
1704 /* Get the function to call, in the form of RTL. */
1706 {
1707 /* If this is the first use of the function, see if we need to
1708 make an external definition for it. */
1710 {
1713 }
1715 /* Get a SYMBOL_REF rtx for the function address. */
1717 }
1718 else
1719 /* Generate an rtx (probably a pseudo-register) for the address. */
1720 {
1721 rtx funaddr;
1723 funaddr = funexp
1727 }
1729 }
1731 /* Do the register loads required for any wholly-register parms or any
1732 parms which are passed both on the stack and in a register. Their
1733 expressions were already evaluated.
1735 Mark all register-parms as living through the call, putting these USE
1736 insns in the CALL_INSN_FUNCTION_USAGE field. */
1738 static void
1744 {
1747 #ifdef LOAD_ARGS_REVERSED
1749 #else
1751 #endif
1752 {
1759 {
1760 /* Set to non-negative if must move a word at a time, even if just
1761 one word (e.g, partial == 1 && mode == DFmode). Set to -1 if
1762 we just use a normal move insn. This value can be zero if the
1763 argument is a zero size structure with no fields. */
1770 /* Handle calls that pass values in multiple non-contiguous
1771 locations. The Irix 6 ABI has examples of this. */
1777 /* If simple case, just do move. If normal partial, store_one_arg
1778 has already loaded the register for us. In all other cases,
1779 load the register(s) from memory. */
1784 /* If we have pre-computed the values to put in the registers in
1785 the case of non-aligned structures, copy them in now. */
1797 /* Handle calls that pass values in multiple non-contiguous
1798 locations. The Irix 6 ABI has examples of this. */
1803 else
1805 }
1806 }
1807 }
1809 /* Try to integrate function. See expand_inline_function for documentation
1810 about the parameters. */
1812 static rtx
1814 tree fndecl;
1815 tree actparms;
1816 rtx target;
1818 tree type;
1819 rtx structure_value_addr;
1820 {
1821 rtx temp;
1822 rtx before_call;
1827 #ifdef REG_PARM_STACK_SPACE
1828 #ifdef MAYBE_REG_PARM_STACK_SPACE
1830 #else
1832 #endif
1833 #endif
1841 structure_value_addr);
1845 /* If inlining succeeded, return. */
1847 {
1849 {
1850 /* If the outgoing argument list must be preserved, push
1851 the stack before executing the inlined function if it
1852 makes any calls. */
1859 {
1860 rtx first_insn
1864 /* Look for a call in the inline function code.
1865 If DECL_SAVED_INSNS (fndecl)->outgoing_args_size is
1866 nonzero then there is a call and it is not necessary
1867 to scan the insns. */
1875 {
1876 /* Reserve enough stack space so that the largest
1877 argument list of any function call in the inline
1878 function does not overlap the argument list being
1879 evaluated. This is usually an overestimate because
1880 allocate_dynamic_stack_space reserves space for an
1881 outgoing argument list in addition to the requested
1882 space, but there is no way to ask for stack space such
1883 that an argument list of a certain length can be
1884 safely constructed.
1886 Add the stack space reserved for register arguments, if
1887 any, in the inline function. What is really needed is the
1888 largest value of reg_parm_stack_space in the inline
1889 function, but that is not available. Using the current
1890 value of reg_parm_stack_space is wrong, but gives
1891 correct results on all supported machines. */
1904 }
1905 }
1906 }
1908 /* If the result is equivalent to TARGET, return TARGET to simplify
1909 checks in store_expr. They can be equivalent but not equal in the
1910 case of a function that returns BLKmode. */
1914 }
1916 /* If inlining failed, mark FNDECL as needing to be compiled
1917 separately after all. If function was declared inline,
1918 give a warning. */
1921 {
1924 }
1927 }
1929 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
1930 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
1931 bytes, then we would need to push some additional bytes to pad the
1932 arguments. So, we compute an adjust to the stack pointer for an
1933 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
1934 bytes. Then, when the arguments are pushed the stack will be perfectly
1935 aligned. ARGS_SIZE->CONSTANT is set to the number of bytes that should
1936 be popped after the call. Returns the adjustment. */
1938 static int
1940 args_size,
1941 preferred_unit_stack_boundary)
1945 {
1946 /* The number of bytes to pop so that the stack will be
1947 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
1948 HOST_WIDE_INT adjustment;
1949 /* The alignment of the stack after the arguments are pushed, if we
1950 just pushed the arguments without adjust the stack here. */
1951 HOST_WIDE_INT unadjusted_alignment;
1953 unadjusted_alignment
1957 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
1958 as possible -- leaving just enough left to cancel out the
1959 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
1960 PENDING_STACK_ADJUST is non-negative, and congruent to
1961 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
1963 /* Begin by trying to pop all the bytes. */
1964 unadjusted_alignment
1965 = (unadjusted_alignment
1968 /* Push enough additional bytes that the stack will be aligned
1969 after the arguments are pushed. */
1971 {
1974 else
1976 }
1978 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
1979 bytes after the call. The right number is the entire
1980 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
1981 by the arguments in the first place. */
1982 args_size->constant
1986 }
1988 /* Scan X expression if it does not dereference any argument slots
1989 we already clobbered by tail call arguments (as noted in stored_args_map
1990 bitmap).
1991 Return nonzero if X expression dereferences such argument slots,
1992 zero otherwise. */
1994 static int
1996 rtx x;
1997 {
1998 RTX_CODE code;
2009 {
2014 current_function_internal_arg_pointer
2017 else
2020 #ifdef ARGS_GROW_DOWNWARD
2022 #endif
2030 }
2032 /* Scan all subexpressions. */
2035 {
2037 {
2040 }
2042 {
2046 }
2047 }
2049 }
2051 /* Scan sequence after INSN if it does not dereference any argument slots
2052 we already clobbered by tail call arguments (as noted in stored_args_map
2053 bitmap). Add stack slots for ARG to stored_args_map bitmap afterwards.
2054 Return nonzero if sequence after INSN dereferences such argument slots,
2055 zero otherwise. */
2057 static int
2059 rtx insn;
2061 {
2066 else
2074 #ifdef ARGS_GROW_DOWNWARD
2076 #else
2078 #endif
2083 }
2085 /* Generate all the code for a function call
2086 and return an rtx for its value.
2087 Store the value in TARGET (specified as an rtx) if convenient.
2088 If the value is stored in TARGET then TARGET is returned.
2089 If IGNORE is nonzero, then we ignore the value of the function call. */
2091 rtx
2093 tree exp;
2094 rtx target;
2096 {
2097 /* Nonzero if we are currently expanding a call. */
2100 /* List of actual parameters. */
2102 /* RTX for the function to be called. */
2103 rtx funexp;
2104 /* Sequence of insns to perform a tail recursive "call". */
2106 /* Sequence of insns to perform a normal "call". */
2108 /* Sequence of insns to perform a tail recursive "call". */
2110 /* Data type of the function. */
2111 tree funtype;
2112 /* Declaration of the function being called,
2113 or 0 if the function is computed (not known by name). */
2115 rtx insn;
2120 /* Register in which non-BLKmode value will be returned,
2121 or 0 if no value or if value is BLKmode. */
2122 rtx valreg;
2123 /* Address where we should return a BLKmode value;
2124 0 if value not BLKmode. */
2126 /* Nonzero if that address is being passed by treating it as
2127 an extra, implicit first parameter. Otherwise,
2128 it is passed by being copied directly into struct_value_rtx. */
2130 /* Size of aggregate value wanted, or zero if none wanted
2131 or if we are using the non-reentrant PCC calling convention
2132 or expecting the value in registers. */
2134 /* Nonzero if called function returns an aggregate in memory PCC style,
2135 by returning the address of where to find it. */
2138 /* Number of actual parameters in this call, including struct value addr. */
2140 /* Number of named args. Args after this are anonymous ones
2141 and they must all go on the stack. */
2144 /* Vector of information about each argument.
2145 Arguments are numbered in the order they will be pushed,
2146 not the order they are written. */
2149 /* Total size in bytes of all the stack-parms scanned so far. */
2152 /* Size of arguments before any adjustments (such as rounding). */
2154 /* Data on reg parms scanned so far. */
2155 CUMULATIVE_ARGS args_so_far;
2156 /* Nonzero if a reg parm has been scanned. */
2158 /* Nonzero if this is an indirect function call. */
2160 /* Nonzero if we must avoid push-insns in the args for this call.
2161 If stack space is allocated for register parameters, but not by the
2162 caller, then it is preallocated in the fixed part of the stack frame.
2163 So the entire argument block must then be preallocated (i.e., we
2164 ignore PUSH_ROUNDING in that case). */
2168 /* Size of the stack reserved for parameter registers. */
2171 /* Address of space preallocated for stack parms
2172 (on machines that lack push insns), or 0 if space not preallocated. */
2175 /* Mask of ECF_ flags. */
2177 /* Nonzero if this is a call to an inline function. */
2179 #ifdef REG_PARM_STACK_SPACE
2180 /* Define the boundary of the register parm stack space that needs to be
2181 save, if any. */
2184 #endif
2194 rtx call_fusage;
2197 /* The alignment of the stack, in bits. */
2198 HOST_WIDE_INT preferred_stack_boundary;
2199 /* The alignment of the stack, in bytes. */
2200 HOST_WIDE_INT preferred_unit_stack_boundary;
2202 /* See if this is "nothrow" function call. */
2206 /* See if we can find a DECL-node for the actual function.
2207 As a result, decide whether this is a call to an integrable function. */
2211 {
2219 {
2220 /* In case this function later becomes inlinable,
2221 record that there was already a non-inline call to it.
2223 Use abstraction instead of setting TREE_ADDRESSABLE
2224 directly. */
2227 {
2230 }
2232 }
2235 }
2237 /* If we don't have specific function to call, see if we have a
2238 attributes set in the type. */
2239 else
2242 #ifdef REG_PARM_STACK_SPACE
2243 #ifdef MAYBE_REG_PARM_STACK_SPACE
2245 #else
2247 #endif
2248 #endif
2250 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2253 #endif
2255 /* Warn if this value is an aggregate type,
2256 regardless of which calling convention we are using for it. */
2260 /* Set up a place to return a structure. */
2262 /* Cater to broken compilers. */
2264 {
2265 /* This call returns a big structure. */
2268 #ifdef PCC_STATIC_STRUCT_RETURN
2269 {
2271 /* Easier than making that case work right. */
2273 {
2274 /* In case this is a static function, note that it has been
2275 used. */
2279 }
2280 }
2282 {
2287 else
2288 {
2289 /* For variable-sized objects, we must be called with a target
2290 specified. If we were to allocate space on the stack here,
2291 we would have no way of knowing when to free it. */
2297 }
2298 }
2300 }
2302 /* If called function is inline, try to integrate it. */
2305 {
2308 structure_value_addr);
2311 }
2313 /* Figure out the amount to which the stack should be aligned. */
2316 /* Operand 0 is a pointer-to-function; get the type of the function. */
2322 /* See if this is a call to a function that can return more than once
2323 or a call to longjmp or malloc. */
2329 /* If struct_value_rtx is 0, it means pass the address
2330 as if it were an extra parameter. */
2332 {
2333 /* If structure_value_addr is a REG other than
2334 virtual_outgoing_args_rtx, we can use always use it. If it
2335 is not a REG, we must always copy it into a register.
2336 If it is virtual_outgoing_args_rtx, we must copy it to another
2337 register in some cases. */
2339 || (ACCUMULATE_OUTGOING_ARGS
2340 && stack_arg_under_construction
2345 actparms
2348 temp),
2349 actparms);
2351 }
2353 /* Count the arguments and set NUM_ACTUALS. */
2355 num_actuals++;
2357 /* Compute number of named args.
2358 Normally, don't include the last named arg if anonymous args follow.
2359 We do include the last named arg if STRICT_ARGUMENT_NAMING is nonzero.
2360 (If no anonymous args follow, the result of list_length is actually
2361 one too large. This is harmless.)
2363 If PRETEND_OUTGOING_VARARGS_NAMED is set and STRICT_ARGUMENT_NAMING is
2364 zero, this machine will be able to place unnamed args that were
2365 passed in registers into the stack. So treat all args as named.
2366 This allows the insns emitting for a specific argument list to be
2367 independent of the function declaration.
2369 If PRETEND_OUTGOING_VARARGS_NAMED is not set, we do not have any
2370 reliable way to pass unnamed args in registers, so we must force
2371 them into memory. */
2376 n_named_args
2378 /* Don't include the last named arg. */
2380 /* Count the struct value address, if it is passed as a parm. */
2382 else
2383 /* If we know nothing, treat all args as named. */
2386 /* Start updating where the next arg would go.
2388 On some machines (such as the PA) indirect calls have a different
2389 calling convention than normal calls. The last argument in
2390 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2391 or not. */
2394 /* Make a vector to hold all the information about each arg. */
2398 /* Build up entries in the ARGS array, compute the size of the
2399 arguments into ARGS_SIZE, etc. */
2407 {
2408 /* If this function requires a variable-sized argument list, don't
2409 try to make a cse'able block for this call. We may be able to
2410 do this eventually, but it is too complicated to keep track of
2411 what insns go in the cse'able block and which don't. */
2415 }
2417 /* Now make final decision about preallocating stack space. */
2422 /* If the structure value address will reference the stack pointer, we
2423 must stabilize it. We don't need to do this if we know that we are
2424 not going to adjust the stack pointer in processing this call. */
2429 structure_value_addr))
2434 /* Tail calls can make things harder to debug, and we're traditionally
2435 pushed these optimizations into -O2. Don't try if we're already
2436 expanding a call, as that means we're an argument. Don't try if
2437 there's cleanups, as we know there's code to follow the call.
2439 If rtx_equal_function_value_matters is false, that means we've
2440 finished with regular parsing. Which means that some of the
2441 machinery we use to generate tail-calls is no longer in place.
2442 This is most often true of sjlj-exceptions, which we couldn't
2443 tail-call to anyway. */
2446 || !flag_optimize_sibling_calls
2447 || !rtx_equal_function_value_matters
2452 /* Tail recursion fails, when we are not dealing with recursive calls. */
2458 /* Rest of purposes for tail call optimizations to fail. */
2460 #ifdef HAVE_sibcall_epilogue
2461 !HAVE_sibcall_epilogue
2462 #else
2463 1
2464 #endif
2465 || !try_tail_call
2466 /* Doing sibling call optimization needs some work, since
2467 structure_value_addr can be allocated on the stack.
2468 It does not seem worth the effort since few optimizable
2469 sibling calls will return a structure. */
2471 /* If the register holding the address is a callee saved
2472 register, then we lose. We have no way to prevent that,
2473 so we only allow calls to named functions. */
2474 /* ??? This could be done by having the insn constraints
2475 use a register class that is all call-clobbered. Any
2476 reload insns generated to fix things up would appear
2477 before the sibcall_epilogue. */
2481 /* If this function requires more stack slots than the current
2482 function, we cannot change it into a sibling call. */
2484 /* If the callee pops its own arguments, then it must pop exactly
2485 the same number of arguments as the current function. */
2489 current_function_args_size))
2493 {
2496 /* Ok, we're going to give the tail call the old college try.
2497 This means we're going to evaluate the function arguments
2498 up to three times. There are two degrees of badness we can
2499 encounter, those that can be unsaved and those that can't.
2500 (See unsafe_for_reeval commentary for details.)
2502 Generate a new argument list. Pass safe arguments through
2503 unchanged. For the easy badness wrap them in UNSAVE_EXPRs.
2504 For hard badness, evaluate them now and put their resulting
2505 rtx in a temporary VAR_DECL.
2507 initialize_argument_information has ordered the array for the
2508 order to be pushed, and we must remember this when reconstructing
2509 the original argument order. */
2512 {
2516 }
2517 else
2518 {
2522 }
2525 {
2527 {
2536 {
2543 }
2548 }
2549 /* We need to build actparms for optimize_tail_recursion. We can
2550 safely trash away TREE_PURPOSE, since it is unused by this
2551 function. */
2554 }
2555 /* Expanding one of those dangerous arguments could have added
2556 cleanups, but otherwise give it a whirl. */
2559 }
2561 /* Generate a tail recursion sequence when calling ourselves. */
2564 {
2565 /* We want to emit any pending stack adjustments before the tail
2566 recursion "call". That way we know any adjustment after the tail
2567 recursion call can be ignored if we indeed use the tail recursion
2568 call expansion. */
2572 /* Emit any queued insns now; otherwise they would end up in
2573 only one of the alternates. */
2576 /* Use a new sequence to hold any RTL we generate. We do not even
2577 know if we will use this RTL yet. The final decision can not be
2578 made until after RTL generation for the entire function is
2579 complete. */
2581 /* If expanding any of the arguments creates cleanups, we can't
2582 do a tailcall. So, we'll need to pop the pending cleanups
2583 list. If, however, all goes well, and there are no cleanups
2584 then the call to expand_start_target_temps will have no
2585 effect. */
2588 {
2591 else
2593 }
2597 /* Restore the original pending stack adjustment for the sibling and
2598 normal call cases below. */
2601 }
2604 {
2605 /* A fork duplicates the profile information, and an exec discards
2606 it. We can't rely on fork/exec to be paired. So write out the
2607 profile information we have gathered so far, and clear it. */
2608 /* ??? When Linux's __clone is called with CLONE_VM set, profiling
2609 is subject to race conditions, just as with multithreaded
2610 programs. */
2613 LCT_ALWAYS_RETURN,
2615 }
2617 /* Ensure current function's preferred stack boundary is at least
2618 what we need. We don't have to increase alignment for recursive
2619 functions. */
2626 function_call_count++;
2628 /* We want to make two insn chains; one for a sibling call, the other
2629 for a normal call. We will select one of the two chains after
2630 initial RTL generation is complete. */
2632 {
2634 /* We want to emit any pending stack adjustments before the tail
2635 recursion "call". That way we know any adjustment after the tail
2636 recursion call can be ignored if we indeed use the tail recursion
2637 call expansion. */
2640 rtx insns;
2644 {
2648 /* Emit any queued insns now; otherwise they would end up in
2649 only one of the alternates. */
2652 /* State variables we need to save and restore between
2653 iterations. */
2656 }
2659 else
2662 /* Other state variables that we must reinitialize each time
2663 through the loop (that are not initialized by the loop itself). */
2667 /* Start a new sequence for the normal call case.
2669 From this point on, if the sibling call fails, we want to set
2670 sibcall_failure instead of continuing the loop. */
2674 {
2675 /* We know at this point that there are not currently any
2676 pending cleanups. If, however, in the process of evaluating
2677 the arguments we were to create some, we'll need to be
2678 able to get rid of them. */
2680 }
2682 /* Don't let pending stack adjusts add up to too much.
2683 Also, do all pending adjustments now if there is any chance
2684 this might be a call to alloca or if we are expanding a sibling
2685 call sequence or if we are calling a function that is to return
2686 with stack pointer depressed. */
2693 /* When calling a const function, we must pop the stack args right away,
2694 so that the pop is deleted or moved with the call. */
2696 NO_DEFER_POP;
2698 #ifdef FINAL_REG_PARM_STACK_SPACE
2701 #endif
2702 /* Precompute any arguments as needed. */
2706 /* Now we are about to start emitting insns that can be deleted
2707 if a libcall is deleted. */
2712 /* Compute the actual size of the argument block required. The variable
2713 and constant sizes must be combined, the size may have to be rounded,
2714 and there may be a minimum required size. When generating a sibcall
2715 pattern, do not round up, since we'll be re-using whatever space our
2716 caller provided. */
2717 unadjusted_args_size
2725 /* The argument block when performing a sibling call is the
2726 incoming argument block. */
2728 {
2730 argblock
2731 #ifdef STACK_GROWS_DOWNWARD
2733 #else
2735 #endif
2738 }
2740 /* If we have no actual push instructions, or shouldn't use them,
2741 make space for all args right now. */
2743 {
2745 {
2749 /* stack_arg_under_construction says whether a stack arg is
2750 being constructed at the old stack level. Pushing the stack
2751 gets a clean outgoing argument block. */
2754 }
2756 }
2757 else
2758 {
2759 /* Note that we must go through the motions of allocating an argument
2760 block even if the size is zero because we may be storing args
2761 in the area reserved for register arguments, which may be part of
2762 the stack frame. */
2766 /* Store the maximum argument space used. It will be pushed by
2767 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2768 checking). */
2774 {
2776 {
2777 /* Since the stack pointer will never be pushed, it is
2778 possible for the evaluation of a parm to clobber
2779 something we have already written to the stack.
2780 Since most function calls on RISC machines do not use
2781 the stack, this is uncommon, but must work correctly.
2783 Therefore, we save any area of the stack that was already
2784 written and that we are using. Here we set up to do this
2785 by making a new stack usage map from the old one. The
2786 actual save will be done by store_one_arg.
2788 Another approach might be to try to reorder the argument
2789 evaluations to avoid this conflicting stack usage. */
2791 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2792 /* Since we will be writing into the entire argument area,
2793 the map must be allocated for its entire size, not just
2794 the part that is the responsibility of the caller. */
2796 #endif
2798 #ifdef ARGS_GROW_DOWNWARD
2801 #else
2803 needed);
2804 #endif
2805 stack_usage_map
2810 initial_highest_arg_in_use);
2814 (highest_outgoing_arg_in_use
2818 /* The address of the outgoing argument list must not be
2819 copied to a register here, because argblock would be left
2820 pointing to the wrong place after the call to
2821 allocate_dynamic_stack_space below. */
2824 }
2825 else
2826 {
2828 {
2829 /* Try to reuse some or all of the pending_stack_adjust
2830 to get this space. */
2831 needed
2832 = (combine_pending_stack_adjustment_and_call
2835 preferred_unit_stack_boundary));
2837 /* combine_pending_stack_adjustment_and_call computes
2838 an adjustment before the arguments are allocated.
2839 Account for them and see whether or not the stack
2840 needs to go up or down. */
2844 {
2845 /* We're releasing stack space. */
2846 /* ??? We can avoid any adjustment at all if we're
2847 already aligned. FIXME. */
2851 }
2852 else
2853 /* We need to allocate space. We'll do that in
2854 push_block below. */
2856 }
2858 /* Special case this because overhead of `push_block' in
2859 this case is non-trivial. */
2862 else
2865 /* We only really need to call `copy_to_reg' in the case
2866 where push insns are going to be used to pass ARGBLOCK
2867 to a function call in ARGS. In that case, the stack
2868 pointer changes value from the allocation point to the
2869 call point, and hence the value of
2870 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2871 as well always do it. */
2874 /* The save/restore code in store_one_arg handles all
2875 cases except one: a constructor call (including a C
2876 function returning a BLKmode struct) to initialize
2877 an argument. */
2879 {
2880 #ifndef OUTGOING_REG_PARM_STACK_SPACE
2883 #else
2885 #endif
2887 {
2889 NULL_RTX);
2892 /* stack_arg_under_construction says whether a stack
2893 arg is being constructed at the old stack level.
2894 Pushing the stack gets a clean outgoing argument
2895 block. */
2896 old_stack_arg_under_construction
2899 /* Make a new map for the new argument list. */
2904 }
2906 BITS_PER_UNIT);
2907 }
2908 /* If argument evaluation might modify the stack pointer,
2909 copy the address of the argument list to a register. */
2912 {
2915 }
2916 }
2917 }
2918 }
2922 /* If we push args individually in reverse order, perform stack alignment
2923 before the first push (the last arg). */
2926 {
2927 /* When the stack adjustment is pending, we get better code
2928 by combining the adjustments. */
2932 {
2933 pending_stack_adjust
2934 = (combine_pending_stack_adjustment_and_call
2937 preferred_unit_stack_boundary));
2939 }
2943 }
2944 /* Now that the stack is properly aligned, pops can't safely
2945 be deferred during the evaluation of the arguments. */
2946 NO_DEFER_POP;
2950 /* Figure out the register where the value, if any, will come back. */
2954 {
2958 else
2960 }
2962 /* Precompute all register parameters. It isn't safe to compute anything
2963 once we have started filling any specific hard regs. */
2966 #ifdef REG_PARM_STACK_SPACE
2967 /* Save the fixed argument area if it's part of the caller's frame and
2968 is clobbered by argument setup for this call. */
2972 #endif
2974 /* Now store (and compute if necessary) all non-register parms.
2975 These come before register parms, since they can require block-moves,
2976 which could clobber the registers used for register parms.
2977 Parms which have partial registers are not stored here,
2978 but we do preallocate space here if they want that. */
2982 {
2987 reg_parm_stack_space)
2992 }
2994 /* If we have a parm that is passed in registers but not in memory
2995 and whose alignment does not permit a direct copy into registers,
2996 make a group of pseudos that correspond to each register that we
2997 will later fill. */
3001 /* Now store any partially-in-registers parm.
3002 This is the last place a block-move can happen. */
3006 {
3011 reg_parm_stack_space)
3016 }
3018 /* If we pushed args in forward order, perform stack alignment
3019 after pushing the last arg. */
3024 /* If register arguments require space on the stack and stack space
3025 was not preallocated, allocate stack space here for arguments
3026 passed in registers. */
3027 #ifdef OUTGOING_REG_PARM_STACK_SPACE
3031 #endif
3033 /* Pass the function the address in which to return a
3034 structure value. */
3036 {
3040 NULL_RTX)));
3044 }
3051 /* Perform postincrements before actually calling the function. */
3054 /* Save a pointer to the last insn before the call, so that we can
3055 later safely search backwards to find the CALL_INSN. */
3058 /* Set up next argument register. For sibling calls on machines
3059 with register windows this should be the incoming register. */
3060 #ifdef FUNCTION_INCOMING_ARG
3064 else
3065 #endif
3069 /* All arguments and registers used for the call must be set up by
3070 now! */
3072 /* Stack must be properly aligned now. */
3076 /* Generate the actual call instruction. */
3082 /* Verify that we've deallocated all the stack we used. */
3087 /* If call is cse'able, make appropriate pair of reg-notes around it.
3088 Test valreg so we don't crash; may safely ignore `const'
3089 if return type is void. Disable for PARALLEL return values, because
3090 we have no way to move such values into a pseudo register. */
3092 {
3093 rtx insns;
3096 {
3100 }
3101 else
3102 {
3106 /* Mark the return value as a pointer if needed. */
3111 /* Construct an "equal form" for the value which mentions all the
3112 arguments in order as well as the function name. */
3126 note);
3131 }
3132 }
3134 {
3138 /* The return value from a malloc-like function is a pointer. */
3144 /* The return value from a malloc-like function can not alias
3145 anything else. */
3150 /* Write out the sequence. */
3155 }
3157 /* For calls to `setjmp', etc., inform flow.c it should complain
3158 if nonvolatile values are live. For functions that cannot return,
3159 inform flow that control does not fall through. */
3162 {
3163 /* The barrier must be emitted
3164 immediately after the CALL_INSN. Some ports emit more
3165 than just a CALL_INSN above, so we must search for it here. */
3169 {
3171 /* There was no CALL_INSN? */
3174 }
3177 }
3182 /* If this function is returning into a memory location marked as
3183 readonly, it means it is initializing that location. But we normally
3184 treat functions as not clobbering such locations, so we need to
3185 specify that this one does. */
3190 /* If value type not void, return an rtx for the value. */
3192 /* If there are cleanups to be called, don't use a hard reg as target.
3193 We need to double check this and see if it matters anymore. */
3195 {
3200 }
3206 {
3208 {
3209 target
3212 structure_value_addr));
3214 }
3215 }
3217 {
3218 /* This is the special C++ case where we need to
3219 know what the true target was. We take care to
3220 never use this value more than once in one expression. */
3224 }
3225 /* Handle calls that return values in multiple non-contiguous locations.
3226 The Irix 6 ABI has examples of this. */
3228 {
3230 {
3231 /* This will only be assigned once, so it can be readonly. */
3238 }
3244 /* We can not support sibling calls for this case. */
3246 }
3250 {
3251 /* TARGET and VALREG cannot be equal at this point because the
3252 latter would not have REG_FUNCTION_VALUE_P true, while the
3253 former would if it were referring to the same register.
3255 If they refer to the same register, this move will be a no-op,
3256 except when function inlining is being done. */
3258 }
3260 {
3263 /* We can not support sibling calls for this case. */
3265 }
3266 else
3269 #ifdef PROMOTE_FUNCTION_RETURN
3270 /* If we promoted this return value, make the proper SUBREG. TARGET
3271 might be const0_rtx here, so be careful. */
3275 {
3280 /* If we don't promote as expected, something is wrong. */
3288 {
3295 }
3299 }
3300 #endif
3302 /* If size of args is variable or this was a constructor call for a stack
3303 argument, restore saved stack-pointer value. */
3306 {
3313 }
3315 {
3316 #ifdef REG_PARM_STACK_SPACE
3318 {
3321 }
3322 #endif
3324 /* If we saved any argument areas, restore them. */
3327 {
3329 rtx stack_area
3336 else
3339 BLOCK_OP_CALL_PARM);
3340 }
3344 }
3346 /* If this was alloca, record the new stack level for nonlocal gotos.
3347 Check for the handler slots since we might not have a save area
3348 for non-local gotos. */
3353 /* Free up storage we no longer need. */
3359 {
3360 /* Undo the fake expand_start_target_temps we did earlier. If
3361 there had been any cleanups created, we've already set
3362 sibcall_failure. */
3364 }
3370 {
3373 /* Restore the pending stack adjustment now that we have
3374 finished generating the sibling call sequence. */
3379 /* Prepare arg structure for next iteration. */
3381 {
3385 }
3388 }
3389 else
3392 /* If something prevents making this a sibling call,
3393 zero out the sequence. */
3396 }
3398 /* The function optimize_sibling_and_tail_recursive_calls doesn't
3399 handle CALL_PLACEHOLDERs inside other CALL_PLACEHOLDERs. This
3400 can happen if the arguments to this function call an inline
3401 function who's expansion contains another CALL_PLACEHOLDER.
3403 If there are any C_Ps in any of these sequences, replace them
3404 with their normal call. */
3421 /* If this was a potential tail recursion site, then emit a
3422 CALL_PLACEHOLDER with the normal and the tail recursion streams.
3423 One of them will be selected later. */
3425 {
3426 /* The tail recursion label must be kept around. We could expose
3427 its use in the CALL_PLACEHOLDER, but that creates unwanted edges
3428 and makes determining true tail recursion sites difficult.
3430 So we set LABEL_PRESERVE_P here, then clear it when we select
3431 one of the call sequences after rtl generation is complete. */
3435 tail_call_insns,
3436 tail_recursion_insns,
3437 tail_recursion_label));
3438 }
3439 else
3442 currently_expanding_call--;
3444 /* If this function returns with the stack pointer depressed, ensure
3445 this block saves and restores the stack pointer, show it was
3446 changed, and adjust for any outgoing arg space. */
3448 {
3453 }
3456 }
3457 \f
3458 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3459 The RETVAL parameter specifies whether return value needs to be saved, other
3460 parameters are documented in the emit_library_call function below. */
3462 static rtx
3465 rtx orgfun;
3466 rtx value;
3471 {
3472 /* Total size in bytes of all the stack-parms scanned so far. */
3474 /* Size of arguments before any adjustments (such as rounding). */
3477 rtx fun;
3482 CUMULATIVE_ARGS args_so_far;
3483 struct arg
3484 {
3485 rtx value;
3487 rtx reg;
3491 rtx save_area;
3492 };
3497 rtx valreg;
3503 rtx before_call;
3506 #ifdef REG_PARM_STACK_SPACE
3507 /* Define the boundary of the register parm stack space that needs to be
3508 save, if any. */
3511 #endif
3513 /* Size of the stack reserved for parameter registers. */
3517 #ifdef REG_PARM_STACK_SPACE
3518 #ifdef MAYBE_REG_PARM_STACK_SPACE
3520 #else
3522 #endif
3523 #endif
3525 /* By default, library functions can not throw. */
3529 {
3556 }
3559 /* Ensure current function's preferred stack boundary is at least
3560 what we need. */
3564 /* If this kind of value comes back in memory,
3565 decide where in memory it should come back. */
3567 {
3570 {
3571 #ifdef PCC_STATIC_STRUCT_RETURN
3572 rtx pointer_reg
3582 else
3584 #endif
3585 /* This call returns a big structure. */
3587 }
3588 }
3589 else
3592 /* ??? Unfinished: must pass the memory address as an argument. */
3594 /* Copy all the libcall-arguments out of the varargs data
3595 and into a vector ARGVEC.
3597 Compute how to pass each argument. We only support a very small subset
3598 of the full argument passing conventions to limit complexity here since
3599 library functions shouldn't have many args. */
3604 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3606 #else
3608 #endif
3615 /* Now we are about to start emitting insns that can be deleted
3616 if a libcall is deleted. */
3622 /* If there's a structure value address to be passed,
3623 either pass it in the special place, or pass it as an extra argument. */
3625 {
3627 nargs++;
3629 /* Make sure it is a reasonable operand for a move or push insn. */
3639 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3642 #endif
3645 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3647 #else
3649 #endif
3659 count++;
3660 }
3663 {
3667 /* We cannot convert the arg value to the mode the library wants here;
3668 must do it earlier where we know the signedness of the arg. */
3673 /* On some machines, there's no way to pass a float to a library fcn.
3674 Pass it as a double instead. */
3675 #ifdef LIBGCC_NEEDS_DOUBLE
3678 #endif
3680 /* There's no need to call protect_from_queue, because
3681 either emit_move_insn or emit_push_insn will do that. */
3683 /* Make sure it is a reasonable operand for a move or push insn. */
3688 #ifdef FUNCTION_ARG_PASS_BY_REFERENCE
3690 {
3691 rtx slot;
3693 #ifdef FUNCTION_ARG_CALLEE_COPIES
3696 #endif
3697 ;
3699 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3700 functions, so we have to pretend this isn't such a function. */
3702 {
3706 }
3709 /* If this was a CONST function, it is now PURE since
3710 it now reads memory. */
3712 {
3715 }
3720 {
3724 }
3725 else
3726 {
3731 build_pointer_type
3735 }
3739 call_fusage);
3743 slot),
3744 call_fusage);
3748 }
3749 #endif
3756 #ifdef FUNCTION_ARG_PARTIAL_NREGS
3759 #else
3761 #endif
3764 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3766 #else
3768 #endif
3783 }
3785 #ifdef FINAL_REG_PARM_STACK_SPACE
3788 #endif
3789 /* If this machine requires an external definition for library
3790 functions, write one out. */
3795 + stack_pointer_delta
3797 / STACK_BYTES
3802 reg_parm_stack_space);
3804 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3806 #endif
3812 {
3813 /* Since the stack pointer will never be pushed, it is possible for
3814 the evaluation of a parm to clobber something we have already
3815 written to the stack. Since most function calls on RISC machines
3816 do not use the stack, this is uncommon, but must work correctly.
3818 Therefore, we save any area of the stack that was already written
3819 and that we are using. Here we set up to do this by making a new
3820 stack usage map from the old one.
3822 Another approach might be to try to reorder the argument
3823 evaluations to avoid this conflicting stack usage. */
3827 #ifndef OUTGOING_REG_PARM_STACK_SPACE
3828 /* Since we will be writing into the entire argument area, the
3829 map must be allocated for its entire size, not just the part that
3830 is the responsibility of the caller. */
3832 #endif
3834 #ifdef ARGS_GROW_DOWNWARD
3837 #else
3839 needed);
3840 #endif
3845 initial_highest_arg_in_use);
3852 /* We must be careful to use virtual regs before they're instantiated,
3853 and real regs afterwards. Loop optimization, for example, can create
3854 new libcalls after we've instantiated the virtual regs, and if we
3855 use virtuals anyway, they won't match the rtl patterns. */
3859 else
3861 }
3862 else
3863 {
3866 }
3868 /* If we push args individually in reverse order, perform stack alignment
3869 before the first push (the last arg). */
3875 {
3878 }
3879 else
3880 {
3883 }
3885 #ifdef REG_PARM_STACK_SPACE
3887 {
3888 /* The argument list is the property of the called routine and it
3889 may clobber it. If the fixed area has been used for previous
3890 parameters, we must save and restore it.
3892 Here we compute the boundary of the that needs to be saved, if any. */
3894 #ifdef ARGS_GROW_DOWNWARD
3896 #else
3898 #endif
3899 {
3908 }
3911 {
3913 enum machine_mode save_mode
3915 rtx stack_area;
3917 /* If we don't have the required alignment, must do this in BLKmode. */
3922 #ifdef ARGS_GROW_DOWNWARD
3927 #else
3931 low_to_save)));
3932 #endif
3934 {
3938 BLOCK_OP_CALL_PARM);
3939 }
3940 else
3941 {
3944 }
3945 }
3946 }
3947 #endif
3949 /* Push the args that need to be pushed. */
3951 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
3952 are to be pushed. */
3954 {
3962 {
3964 {
3965 /* If this is being stored into a pre-allocated, fixed-size,
3966 stack area, save any previous data at that location. */
3968 #ifdef ARGS_GROW_DOWNWARD
3969 /* stack_slot is negative, but we want to index stack_usage_map
3970 with positive values. */
3973 #else
3976 #endif
3980 /* Don't store things in the fixed argument area at this
3981 point; it has already been saved. */
3986 {
3987 /* We need to make a save area. See what mode we can make
3988 it. */
3989 enum machine_mode save_mode
3993 rtx stack_area
3994 = gen_rtx_MEM
3996 memory_address
4003 }
4004 }
4011 /* Now mark the segment we just used. */
4016 NO_DEFER_POP;
4017 }
4018 }
4020 /* If we pushed args in forward order, perform stack alignment
4021 after pushing the last arg. */
4028 else
4033 /* Now load any reg parms into their regs. */
4035 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4036 are to be pushed. */
4038 {
4043 /* Handle calls that pass values in multiple non-contiguous
4044 locations. The PA64 has examples of this for library calls. */
4050 NO_DEFER_POP;
4051 }
4053 /* Any regs containing parms remain in use through the call. */
4055 {
4061 }
4063 /* Pass the function the address in which to return a structure value. */
4065 {
4069 NULL_RTX)));
4072 }
4074 /* Don't allow popping to be deferred, since then
4075 cse'ing of library calls could delete a call and leave the pop. */
4076 NO_DEFER_POP;
4080 /* Stack must be properly aligned now. */
4086 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4087 will set inhibit_defer_pop to that value. */
4088 /* The return type is needed to decide how many bytes the function pops.
4089 Signedness plays no role in that, so for simplicity, we pretend it's
4090 always signed. We also assume that the list of arguments passed has
4091 no impact, so we pretend it is unknown. */
4097 struct_value_size,
4099 valreg,
4102 /* For calls to `setjmp', etc., inform flow.c it should complain
4103 if nonvolatile values are live. For functions that cannot return,
4104 inform flow that control does not fall through. */
4107 {
4108 /* The barrier note must be emitted
4109 immediately after the CALL_INSN. Some ports emit more than
4110 just a CALL_INSN above, so we must search for it here. */
4114 {
4116 /* There was no CALL_INSN? */
4119 }
4122 }
4124 /* Now restore inhibit_defer_pop to its actual original value. */
4125 OK_DEFER_POP;
4127 /* If call is cse'able, make appropriate pair of reg-notes around it.
4128 Test valreg so we don't crash; may safely ignore `const'
4129 if return type is void. Disable for PARALLEL return values, because
4130 we have no way to move such values into a pseudo register. */
4132 {
4133 rtx insns;
4136 {
4140 }
4141 else
4142 {
4147 /* Construct an "equal form" for the value which mentions all the
4148 arguments in order as well as the function name. */
4161 note);
4166 }
4167 }
4170 /* Copy the value to the right place. */
4172 {
4174 {
4179 }
4182 else
4184 }
4187 {
4188 #ifdef REG_PARM_STACK_SPACE
4190 {
4192 #ifdef ARGS_GROW_DOWNWARD
4193 rtx stack_area
4198 #else
4199 rtx stack_area
4203 #endif
4208 else
4211 BLOCK_OP_CALL_PARM);
4212 }
4213 #endif
4215 /* If we saved any argument areas, restore them. */
4218 {
4220 rtx stack_area
4222 memory_address
4228 }
4232 }
4236 }
4237 \f
4238 /* Output a library call to function FUN (a SYMBOL_REF rtx)
4239 (emitting the queue unless NO_QUEUE is nonzero),
4240 for a value of mode OUTMODE,
4241 with NARGS different arguments, passed as alternating rtx values
4242 and machine_modes to convert them to.
4243 The rtx values should have been passed through protect_from_queue already.
4245 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
4246 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
4247 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
4248 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
4249 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
4250 or other LCT_ value for other types of library calls. */
4252 void
4255 {
4265 }
4266 \f
4267 /* Like emit_library_call except that an extra argument, VALUE,
4268 comes second and says where to store the result.
4269 (If VALUE is zero, this function chooses a convenient way
4270 to return the value.
4272 This function returns an rtx for where the value is to be found.
4273 If VALUE is nonzero, VALUE is returned. */
4275 rtx
4279 {
4280 rtx result;
4295 }
4296 \f
4297 /* Store a single argument for a function call
4298 into the register or memory area where it must be passed.
4299 *ARG describes the argument value and where to pass it.
4301 ARGBLOCK is the address of the stack-block for all the arguments,
4302 or 0 on a machine where arguments are pushed individually.
4304 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4305 so must be careful about how the stack is used.
4307 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4308 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4309 that we need not worry about saving and restoring the stack.
4311 FNDECL is the declaration of the function we are calling.
4313 Return nonzero if this arg should cause sibcall failure,
4314 zero otherwise. */
4316 static int
4319 rtx argblock;
4323 {
4334 /* Push a new temporary level for any temporaries we make for
4335 this argument. */
4339 {
4340 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4341 save any previous data at that location. */
4343 {
4344 #ifdef ARGS_GROW_DOWNWARD
4345 /* stack_slot is negative, but we want to index stack_usage_map
4346 with positive values. */
4349 else
4353 #else
4356 else
4360 #endif
4364 /* Don't store things in the fixed argument area at this point;
4365 it has already been saved. */
4370 {
4371 /* We need to make a save area. See what mode we can make it. */
4372 enum machine_mode save_mode
4374 rtx stack_area
4380 {
4389 BLOCK_OP_CALL_PARM);
4390 }
4391 else
4392 {
4395 }
4396 }
4397 }
4398 /* Now that we have saved any slots that will be overwritten by this
4399 store, mark all slots this store will use. We must do this before
4400 we actually expand the argument since the expansion itself may
4401 trigger library calls which might need to use the same stack slot. */
4405 }
4407 /* If this isn't going to be placed on both the stack and in registers,
4408 set up the register and number of words. */
4410 {
4413 else
4416 }
4419 /* Being passed entirely in a register. We shouldn't be called in
4420 this case. */
4423 /* If this arg needs special alignment, don't load the registers
4424 here. */
4428 /* If this is being passed partially in a register, we can't evaluate
4429 it directly into its stack slot. Otherwise, we can. */
4431 {
4432 /* stack_arg_under_construction is nonzero if a function argument is
4433 being evaluated directly into the outgoing argument list and
4434 expand_call must take special action to preserve the argument list
4435 if it is called recursively.
4437 For scalar function arguments stack_usage_map is sufficient to
4438 determine which stack slots must be saved and restored. Scalar
4439 arguments in general have pass_on_stack == 0.
4441 If this argument is initialized by a function which takes the
4442 address of the argument (a C++ constructor or a C function
4443 returning a BLKmode structure), then stack_usage_map is
4444 insufficient and expand_call must push the stack around the
4445 function call. Such arguments have pass_on_stack == 1.
4447 Note that it is always safe to set stack_arg_under_construction,
4448 but this generates suboptimal code if set when not needed. */
4451 stack_arg_under_construction++;
4454 (partial
4459 /* If we are promoting object (or for any other reason) the mode
4460 doesn't agree, convert the mode. */
4467 stack_arg_under_construction--;
4468 }
4470 /* Don't allow anything left on stack from computation
4471 of argument to alloca. */
4476 /* If the value is already in the stack slot, we are done. */
4477 ;
4479 {
4482 /* Argument is a scalar, not entirely passed in registers.
4483 (If part is passed in registers, arg->partial says how much
4484 and emit_push_insn will take care of putting it there.)
4486 Push it, and if its size is less than the
4487 amount of space allocated to it,
4488 also bump stack pointer by the additional space.
4489 Note that in C the default argument promotions
4490 will prevent such mismatches. */
4493 /* Compute how much space the push instruction will push.
4494 On many machines, pushing a byte will advance the stack
4495 pointer by a halfword. */
4496 #ifdef PUSH_ROUNDING
4498 #endif
4501 /* Compute how much space the argument should get:
4502 round up to a multiple of the alignment for arguments. */
4508 /* This isn't already where we want it on the stack, so put it there.
4509 This can either be done with push or copy insns. */
4515 /* Unless this is a partially-in-register argument, the argument is now
4516 in the stack. */
4519 }
4520 else
4521 {
4522 /* BLKmode, at least partly to be pushed. */
4526 rtx size_rtx;
4528 /* Pushing a nonscalar.
4529 If part is passed in registers, PARTIAL says how much
4530 and emit_push_insn will take care of putting it there. */
4532 /* Round its size up to a multiple
4533 of the allocation unit for arguments. */
4536 {
4539 }
4540 else
4541 {
4542 /* PUSH_ROUNDING has no effect on us, because
4543 emit_push_insn for BLKmode is careful to avoid it. */
4548 }
4550 /* Some types will require stricter alignment, which will be
4551 provided for elsewhere in argument layout. */
4554 /* When an argument is padded down, the block is aligned to
4555 PARM_BOUNDARY, but the actual argument isn't. */
4557 {
4561 {
4564 }
4565 }
4568 {
4569 /* emit_push_insn might not work properly if arg->value and
4570 argblock + arg->offset areas overlap. */
4577 current_function_internal_arg_pointer
4579 {
4583 /* expand_call should ensure this */
4588 {
4591 }
4593 {
4596 }
4597 }
4598 }
4600 /* Special handling is required if part of the parameter lies in the
4601 register parameter area. The argument may be copied into the stack
4602 slot using memcpy(), but the original contents of the register
4603 parameter area will be restored after the memcpy() call.
4605 To ensure that the part that lies in the register parameter area
4606 is copied correctly, we emit a separate push for that part. This
4607 push should be small enough to avoid a call to memcpy(). */
4608 #ifndef STACK_PARMS_IN_REG_PARM_AREA
4610 #else
4612 #endif
4613 {
4621 {
4627 }
4628 }
4636 /* Unless this is a partially-in-register argument, the argument is now
4637 in the stack.
4639 ??? Unlike the case above, in which we want the actual
4640 address of the data, so that we can load it directly into a
4641 register, here we want the address of the stack slot, so that
4642 it's properly aligned for word-by-word copying or something
4643 like that. It's not clear that this is always correct. */
4646 }
4648 /* Once we have pushed something, pops can't safely
4649 be deferred during the rest of the arguments. */
4650 NO_DEFER_POP;
4652 /* ANSI doesn't require a sequence point here,
4653 but PCC has one, so this will avoid some problems. */
4656 /* Free any temporary slots made in processing this argument. Show
4657 that we might have taken the address of something and pushed that
4658 as an operand. */
4664 }