| blob | 4089bb14ea13b86a7738170d7904140506700380 |
1 /* Convert function calls to rtl insns, for GNU C compiler.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
21 02110-1301, USA. */
45 /* Like PREFERRED_STACK_BOUNDARY but in units of bytes, not bits. */
46 #define STACK_BYTES (PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT)
48 /* Data structure and subroutines used within expand_call. */
50 struct arg_data
51 {
52 /* Tree node for this argument. */
53 tree tree_value;
54 /* Mode for value; TYPE_MODE unless promoted. */
56 /* Current RTL value for argument, or 0 if it isn't precomputed. */
57 rtx value;
58 /* Initially-compute RTL value for argument; only for const functions. */
59 rtx initial_value;
60 /* Register to pass this argument in, 0 if passed on stack, or an
61 PARALLEL if the arg is to be copied into multiple non-contiguous
62 registers. */
63 rtx reg;
64 /* Register to pass this argument in when generating tail call sequence.
65 This is not the same register as for normal calls on machines with
66 register windows. */
67 rtx tail_call_reg;
68 /* If REG is a PARALLEL, this is a copy of VALUE pulled into the correct
69 form for emit_group_move. */
70 rtx parallel_value;
71 /* If REG was promoted from the actual mode of the argument expression,
72 indicates whether the promotion is sign- or zero-extended. */
74 /* Number of bytes to put in registers. 0 means put the whole arg
75 in registers. Also 0 if not passed in registers. */
77 /* Nonzero if argument must be passed on stack.
78 Note that some arguments may be passed on the stack
79 even though pass_on_stack is zero, just because FUNCTION_ARG says so.
80 pass_on_stack identifies arguments that *cannot* go in registers. */
82 /* Some fields packaged up for locate_and_pad_parm. */
84 /* Location on the stack at which parameter should be stored. The store
85 has already been done if STACK == VALUE. */
86 rtx stack;
87 /* Location on the stack of the start of this argument slot. This can
88 differ from STACK if this arg pads downward. This location is known
89 to be aligned to FUNCTION_ARG_BOUNDARY. */
90 rtx stack_slot;
91 /* Place that this stack area has been saved, if needed. */
92 rtx save_area;
93 /* If an argument's alignment does not permit direct copying into registers,
94 copy in smaller-sized pieces into pseudos. These are stored in a
95 block pointed to by this field. The next field says how many
96 word-sized pseudos we made. */
99 };
101 /* A vector of one char per byte of stack space. A byte if nonzero if
102 the corresponding stack location has been used.
103 This vector is used to prevent a function call within an argument from
104 clobbering any stack already set up. */
107 /* Size of STACK_USAGE_MAP. */
110 /* A bitmap of virtual-incoming stack space. Bit is set if the corresponding
111 stack location's tail call argument has been already stored into the stack.
112 This bitmap is used to prevent sibling call optimization if function tries
113 to use parent's incoming argument slots when they have been already
114 overwritten with tail call arguments. */
117 /* stack_arg_under_construction is nonzero when an argument may be
118 initialized with a constructor call (including a C function that
119 returns a BLKmode struct) and expand_call must take special action
120 to make sure the object being constructed does not overlap the
121 argument list for the constructor call. */
126 CUMULATIVE_ARGS *);
154 #ifdef REG_PARM_STACK_SPACE
157 #endif
158 \f
159 /* Force FUNEXP into a form suitable for the address of a CALL,
160 and return that as an rtx. Also load the static chain register
161 if FNDECL is a nested function.
163 CALL_FUSAGE points to a variable holding the prospective
164 CALL_INSN_FUNCTION_USAGE information. */
166 rtx
169 {
170 /* Make a valid memory address and copy constants through pseudo-regs,
171 but not for a constant address if -fno-function-cse. */
173 /* If we are using registers for parameters, force the
174 function address into a register now. */
179 {
180 #ifndef NO_FUNCTION_CSE
183 #endif
184 }
187 {
193 }
196 }
198 /* Generate instructions to call function FUNEXP,
199 and optionally pop the results.
200 The CALL_INSN is the first insn generated.
202 FNDECL is the declaration node of the function. This is given to the
203 macro RETURN_POPS_ARGS to determine whether this function pops its own args.
205 FUNTYPE is the data type of the function. This is given to the macro
206 RETURN_POPS_ARGS to determine whether this function pops its own args.
207 We used to allow an identifier for library functions, but that doesn't
208 work when the return type is an aggregate type and the calling convention
209 says that the pointer to this aggregate is to be popped by the callee.
211 STACK_SIZE is the number of bytes of arguments on the stack,
212 ROUNDED_STACK_SIZE is that number rounded up to
213 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
214 both to put into the call insn and to generate explicit popping
215 code if necessary.
217 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
218 It is zero if this call doesn't want a structure value.
220 NEXT_ARG_REG is the rtx that results from executing
221 FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1)
222 just after all the args have had their registers assigned.
223 This could be whatever you like, but normally it is the first
224 arg-register beyond those used for args in this call,
225 or 0 if all the arg-registers are used in this call.
226 It is passed on to `gen_call' so you can put this info in the call insn.
228 VALREG is a hard register in which a value is returned,
229 or 0 if the call does not return a value.
231 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
232 the args to this call were processed.
233 We restore `inhibit_defer_pop' to that value.
235 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
236 denote registers used by the called function. */
238 static void
240 tree funtype ATTRIBUTE_UNUSED,
241 HOST_WIDE_INT stack_size ATTRIBUTE_UNUSED,
242 HOST_WIDE_INT rounded_stack_size,
243 HOST_WIDE_INT struct_value_size ATTRIBUTE_UNUSED,
247 {
249 rtx call_insn;
252 #if defined (HAVE_call) && defined (HAVE_call_value)
253 rtx struct_value_size_rtx;
255 #endif
257 #ifdef CALL_POPS_ARGS
259 #endif
261 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
262 and we don't want to load it into a register as an optimization,
263 because prepare_call_address already did it if it should be done. */
267 #if defined (HAVE_sibcall_pop) && defined (HAVE_sibcall_value_pop)
271 {
273 rtx pat;
275 /* If this subroutine pops its own args, record that in the call insn
276 if possible, for the sake of frame pointer elimination. */
282 n_pop);
283 else
289 }
290 else
291 #endif
293 #if defined (HAVE_call_pop) && defined (HAVE_call_value_pop)
294 /* If the target has "call" or "call_value" insns, then prefer them
295 if no arguments are actually popped. If the target does not have
296 "call" or "call_value" insns, then we must use the popping versions
297 even if the call has no arguments to pop. */
298 #if defined (HAVE_call) && defined (HAVE_call_value)
301 #else
303 #endif
304 {
306 rtx pat;
308 /* If this subroutine pops its own args, record that in the call insn
309 if possible, for the sake of frame pointer elimination. */
315 else
321 }
322 else
323 #endif
325 #if defined (HAVE_sibcall) && defined (HAVE_sibcall_value)
328 {
332 rounded_stack_size_rtx,
334 else
337 struct_value_size_rtx));
338 }
339 else
340 #endif
342 #if defined (HAVE_call) && defined (HAVE_call_value)
344 {
349 NULL_RTX));
350 else
353 struct_value_size_rtx));
354 }
355 else
356 #endif
359 /* Find the call we just emitted. */
362 /* Mark memory as used for "pure" function call. */
364 call_fusage
365 = gen_rtx_EXPR_LIST
369 call_fusage);
371 /* Put the register usage information there. */
374 /* If this is a const call, then set the insn's unchanging bit. */
378 /* If this call can't throw, attach a REG_EH_REGION reg note to that
379 effect. */
383 else
384 {
387 /* If rn < 0, then either (1) tree-ssa not used or (2) doesn't
388 throw, which we already took care of. */
393 }
400 {
404 }
408 /* Restore this now, so that we do defer pops for this call's args
409 if the context of the call as a whole permits. */
413 {
422 }
425 {
426 /* If returning from the subroutine does not automatically pop the args,
427 we need an instruction to pop them sooner or later.
428 Perhaps do it now; perhaps just record how much space to pop later.
430 If returning from the subroutine does pop the args, indicate that the
431 stack pointer will be changed. */
434 {
436 /* Just pretend we did the pop. */
441 else
443 }
444 }
445 /* When we accumulate outgoing args, we must avoid any stack manipulations.
446 Restore the stack pointer to its original value now. Usually
447 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
448 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
449 popping variants of functions exist as well.
451 ??? We may optimize similar to defer_pop above, but it is
452 probably not worthwhile.
454 ??? It will be worthwhile to enable combine_stack_adjustments even for
455 such machines. */
458 }
460 /* Determine if the function identified by NAME and FNDECL is one with
461 special properties we wish to know about.
463 For example, if the function might return more than one time (setjmp), then
464 set RETURNS_TWICE to a nonzero value.
466 Similarly set NORETURN if the function is in the longjmp family.
468 Set MAY_BE_ALLOCA for any memory allocation function that might allocate
469 space from the stack such as alloca. */
471 static int
473 {
476 /* Exclude functions not at the file scope, or not `extern',
477 since they are not the magic functions we would otherwise
478 think they are.
479 FIXME: this should be handled with attributes, not with this
480 hacky imitation of DECL_ASSEMBLER_NAME. It's (also) wrong
481 because you can declare fork() inside a function if you
482 wish. */
486 {
490 /* We assume that alloca will always be called by name. It
491 makes no sense to pass it as a pointer-to-function to
492 anything that does not understand its behavior. */
501 /* Disregard prefix _, __ or __x. */
503 {
508 else
510 }
513 {
526 }
538 }
541 }
543 /* Return nonzero when FNDECL represents a call to setjmp. */
545 int
547 {
549 }
551 /* Return true when exp contains alloca call. */
552 bool
554 {
562 }
564 /* Detect flags (function attributes) from the function decl or type node. */
566 int
568 {
573 {
576 /* The function exp may have the `malloc' attribute. */
580 /* The function exp may have the `returns_twice' attribute. */
584 /* The function exp may have the `pure' attribute. */
598 }
605 /* Mark if the function returns with the stack pointer depressed. We
606 cannot consider it pure or constant in that case. */
608 {
611 }
614 }
616 /* Detect flags from a CALL_EXPR. */
618 int
620 {
626 else
627 {
631 else
633 }
636 }
638 /* Precompute all register parameters as described by ARGS, storing values
639 into fields within the ARGS array.
641 NUM_ACTUALS indicates the total number elements in the ARGS array.
643 Set REG_PARM_SEEN if we encounter a register parameter. */
645 static void
648 {
655 {
659 {
664 }
666 /* If the value is a non-legitimate constant, force it into a
667 pseudo now. TLS symbols sometimes need a call to resolve. */
672 /* If we are to promote the function arg to a wider mode,
673 do it now. */
681 /* If we're going to have to load the value by parts, pull the
682 parts into pseudos. The part extraction process can involve
683 non-trivial computation. */
685 {
690 }
692 /* If the value is expensive, and we are inside an appropriately
693 short loop, put the value into a pseudo and then put the pseudo
694 into the hard reg.
696 For small register classes, also do this if this call uses
697 register parameters. This is to avoid reload conflicts while
698 loading the parameters registers. */
708 }
709 }
711 #ifdef REG_PARM_STACK_SPACE
713 /* The argument list is the property of the called routine and it
714 may clobber it. If the fixed area has been used for previous
715 parameters, we must save and restore it. */
717 static rtx
718 save_fixed_argument_area (int reg_parm_stack_space, rtx argblock, int *low_to_save, int *high_to_save)
719 {
723 /* Compute the boundary of the area that needs to be saved, if any. */
725 #ifdef ARGS_GROW_DOWNWARD
727 #endif
733 {
737 rtx stack_area;
738 rtx save_area;
741 ;
749 /* If we don't have the required alignment, must do this
750 in BLKmode. */
755 #ifdef ARGS_GROW_DOWNWARD
757 #else
759 #endif
763 delta)));
767 {
771 }
772 else
773 {
776 }
779 }
782 }
784 static void
786 {
789 rtx stack_area;
791 #ifdef ARGS_GROW_DOWNWARD
793 #else
795 #endif
803 else
806 BLOCK_OP_CALL_PARM);
807 }
810 /* If any elements in ARGS refer to parameters that are to be passed in
811 registers, but not in memory, and whose alignment does not permit a
812 direct copy into registers. Copy the values into a group of pseudos
813 which we will later copy into the appropriate hard registers.
815 Pseudos for each unaligned argument will be stored into the array
816 args[argnum].aligned_regs. The caller is responsible for deallocating
817 the aligned_regs array if it is nonzero. */
819 static void
821 {
829 {
834 {
837 }
838 else
839 {
842 }
846 /* Structures smaller than a word are normally aligned to the
847 least significant byte. On a BYTES_BIG_ENDIAN machine,
848 this means we must skip the empty high order bytes when
849 calculating the bit offset. */
851 #ifdef BLOCK_REG_PADDING
855 #else
856 && BYTES_BIG_ENDIAN
857 #endif
858 )
862 {
871 /* There is no need to restrict this code to loading items
872 in TYPE_ALIGN sized hunks. The bitfield instructions can
873 load up entire word sized registers efficiently.
875 ??? This may not be needed anymore.
876 We use to emit a clobber here but that doesn't let later
877 passes optimize the instructions we emit. By storing 0 into
878 the register later passes know the first AND to zero out the
879 bitfield being set in the register is unnecessary. The store
880 of 0 will be deleted as will at least the first AND. */
886 word);
887 }
888 }
889 }
891 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
892 CALL_EXPR EXP.
894 NUM_ACTUALS is the total number of parameters.
896 N_NAMED_ARGS is the total number of named arguments.
898 STRUCT_VALUE_ADDR_VALUE is the implicit argument for a struct return
899 value, or null.
901 FNDECL is the tree code for the target of this call (if known)
903 ARGS_SO_FAR holds state needed by the target to know where to place
904 the next argument.
906 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
907 for arguments which are passed in registers.
909 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
910 and may be modified by this routine.
912 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
913 flags which may may be modified by this routine.
915 MAY_TAILCALL is cleared if we encounter an invisible pass-by-reference
916 that requires allocation of stack space.
918 CALL_FROM_THUNK_P is true if this call is the jump from a thunk to
919 the thunked-to function. */
921 static void
927 tree fndecl,
933 {
934 /* 1 if scanning parms front to back, -1 if scanning back to front. */
937 /* Count arg position in order args appear. */
945 /* In this loop, we consider args in the order they are written.
946 We fill up ARGS from the front or from the back if necessary
947 so that in any case the first arg to be pushed ends up at the front. */
950 {
952 /* In this case, must reverse order of args
953 so that we compute and push the last arg first. */
954 }
955 else
956 {
958 }
960 /* First fill in the actual arguments in the ARGS array, splitting
961 complex arguments if necessary. */
962 {
964 call_expr_arg_iterator iter;
965 tree arg;
968 {
971 }
973 {
976 && argtype
979 {
985 }
986 else
989 }
990 }
992 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
994 {
999 /* Replace erroneous argument with constant zero. */
1003 /* If TYPE is a transparent union, pass things the way we would
1004 pass the first field of the union. We have already verified that
1005 the modes are the same. */
1009 /* Decide where to pass this arg.
1011 args[i].reg is nonzero if all or part is passed in registers.
1013 args[i].partial is nonzero if part but not all is passed in registers,
1014 and the exact value says how many bytes are passed in registers.
1016 args[i].pass_on_stack is nonzero if the argument must at least be
1017 computed on the stack. It may then be loaded back into registers
1018 if args[i].reg is nonzero.
1020 These decisions are driven by the FUNCTION_... macros and must agree
1021 with those made by function.c. */
1023 /* See if this argument should be passed by invisible reference. */
1026 {
1028 tree base;
1030 callee_copies
1034 /* If we're compiling a thunk, pass through invisible references
1035 instead of making a copy. */
1037 || (callee_copies
1041 {
1042 /* We can't use sibcalls if a callee-copied argument is
1043 stored in the current function's frame. */
1051 }
1052 else
1053 {
1054 /* We make a copy of the object and pass the address to the
1055 function being called. */
1056 rtx copy;
1062 STACK_CHECK_MAX_VAR_SIZE))))
1063 {
1064 /* This is a variable-sized object. Make space on the stack
1065 for it. */
1069 {
1073 }
1076 allocate_dynamic_stack_space
1079 }
1080 else
1087 else
1094 }
1095 }
1108 #ifdef FUNCTION_INCOMING_ARG
1109 /* If this is a sibling call and the machine has register windows, the
1110 register window has to be unwinded before calling the routine, so
1111 arguments have to go into the incoming registers. */
1114 #else
1116 #endif
1125 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1126 it means that we are to pass this arg in the register(s) designated
1127 by the PARALLEL, but also to pass it in the stack. */
1132 /* If this is an addressable type, we must preallocate the stack
1133 since we must evaluate the object into its final location.
1135 If this is to be passed in both registers and the stack, it is simpler
1136 to preallocate. */
1141 /* If this is an addressable type, we cannot pre-evaluate it. Thus,
1142 we cannot consider this function call constant. */
1146 /* Compute the stack-size of this argument. */
1151 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1153 #else
1155 #endif
1158 #ifdef BLOCK_REG_PADDING
1159 else
1160 /* The argument is passed entirely in registers. See at which
1161 end it should be padded. */
1165 #endif
1167 /* Update ARGS_SIZE, the total stack space for args so far. */
1173 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1174 have been used, etc. */
1178 }
1179 }
1181 /* Update ARGS_SIZE to contain the total size for the argument block.
1182 Return the original constant component of the argument block's size.
1184 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1185 for arguments passed in registers. */
1187 static int
1191 {
1194 /* For accumulate outgoing args mode we don't need to align, since the frame
1195 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1196 backends from generating misaligned frame sizes. */
1200 /* Compute the actual size of the argument block required. The variable
1201 and constant sizes must be combined, the size may have to be rounded,
1202 and there may be a minimum required size. */
1205 {
1211 {
1212 /* We don't handle this case yet. To handle it correctly we have
1213 to add the delta, round and subtract the delta.
1214 Currently no machine description requires this support. */
1217 }
1220 {
1221 args_size->var
1225 /* The area corresponding to register parameters is not to count in
1226 the size of the block we need. So make the adjustment. */
1228 args_size->var
1231 }
1232 }
1233 else
1234 {
1239 + stack_pointer_delta
1241 / preferred_stack_boundary
1246 reg_parm_stack_space);
1250 }
1252 }
1254 /* Precompute parameters as needed for a function call.
1256 FLAGS is mask of ECF_* constants.
1258 NUM_ACTUALS is the number of arguments.
1260 ARGS is an array containing information for each argument; this
1261 routine fills in the INITIAL_VALUE and VALUE fields for each
1262 precomputed argument. */
1264 static void
1266 {
1269 /* If this is a libcall, then precompute all arguments so that we do not
1270 get extraneous instructions emitted as part of the libcall sequence. */
1275 {
1278 /* If this is an addressable type, we cannot pre-evaluate it. */
1286 {
1290 #if defined(PROMOTE_FUNCTION_MODE) && !defined(PROMOTE_MODE)
1291 /* CSE will replace this only if it contains args[i].value
1292 pseudo, so convert it down to the declared mode using
1293 a SUBREG. */
1296 {
1302 }
1303 #endif
1304 }
1305 }
1306 }
1308 /* Given the current state of MUST_PREALLOCATE and information about
1309 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1310 compute and return the final value for MUST_PREALLOCATE. */
1312 static int
1315 {
1316 /* See if we have or want to preallocate stack space.
1318 If we would have to push a partially-in-regs parm
1319 before other stack parms, preallocate stack space instead.
1321 If the size of some parm is not a multiple of the required stack
1322 alignment, we must preallocate.
1324 If the total size of arguments that would otherwise create a copy in
1325 a temporary (such as a CALL) is more than half the total argument list
1326 size, preallocation is faster.
1328 Another reason to preallocate is if we have a machine (like the m88k)
1329 where stack alignment is required to be maintained between every
1330 pair of insns, not just when the call is made. However, we assume here
1331 that such machines either do not have push insns (and hence preallocation
1332 would occur anyway) or the problem is taken care of with
1333 PUSH_ROUNDING. */
1336 {
1342 {
1353 copy_to_evaluate_size
1355 }
1360 }
1362 }
1364 /* If we preallocated stack space, compute the address of each argument
1365 and store it into the ARGS array.
1367 We need not ensure it is a valid memory address here; it will be
1368 validized when it is used.
1370 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1372 static void
1374 {
1376 {
1384 {
1387 rtx addr;
1392 /* Skip this parm if it will not be passed on the stack. */
1400 else
1406 {
1407 /* Only part of the parameter is being passed on the stack.
1408 Generate a simple memory reference of the correct size. */
1414 }
1415 else
1416 {
1420 }
1426 {
1429 }
1434 else
1440 {
1441 /* Only part of the parameter is being passed on the stack.
1442 Generate a simple memory reference of the correct size.
1443 */
1446 }
1447 else
1448 {
1452 }
1455 /* Function incoming arguments may overlap with sibling call
1456 outgoing arguments and we cannot allow reordering of reads
1457 from function arguments with stores to outgoing arguments
1458 of sibling calls. */
1461 }
1462 }
1463 }
1465 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1466 in a call instruction.
1468 FNDECL is the tree node for the target function. For an indirect call
1469 FNDECL will be NULL_TREE.
1471 ADDR is the operand 0 of CALL_EXPR for this call. */
1473 static rtx
1475 {
1476 rtx funexp;
1478 /* Get the function to call, in the form of RTL. */
1480 {
1481 /* If this is the first use of the function, see if we need to
1482 make an external definition for it. */
1484 {
1487 }
1489 /* Get a SYMBOL_REF rtx for the function address. */
1491 }
1492 else
1493 /* Generate an rtx (probably a pseudo-register) for the address. */
1494 {
1498 }
1500 }
1502 /* Return true if and only if SIZE storage units (usually bytes)
1503 starting from address ADDR overlap with already clobbered argument
1504 area. This function is used to determine if we should give up a
1505 sibcall. */
1507 static bool
1509 {
1510 HOST_WIDE_INT i;
1518 /* Return true for arg pointer based indexed addressing. */
1523 else
1526 #ifdef ARGS_GROW_DOWNWARD
1528 #endif
1530 {
1537 }
1540 }
1542 /* Do the register loads required for any wholly-register parms or any
1543 parms which are passed both on the stack and in a register. Their
1544 expressions were already evaluated.
1546 Mark all register-parms as living through the call, putting these USE
1547 insns in the CALL_INSN_FUNCTION_USAGE field.
1549 When IS_SIBCALL, perform the check_sibcall_argument_overlap
1550 checking, setting *SIBCALL_FAILURE if appropriate. */
1552 static void
1556 {
1560 {
1564 {
1569 /* Set non-negative if we must move a word at a time, even if
1570 just one word (e.g, partial == 4 && mode == DFmode). Set
1571 to -1 if we just use a normal move insn. This value can be
1572 zero if the argument is a zero size structure. */
1575 ;
1577 {
1580 }
1582 {
1585 }
1586 else
1589 /* Handle calls that pass values in multiple non-contiguous
1590 locations. The Irix 6 ABI has examples of this. */
1595 /* If simple case, just do move. If normal partial, store_one_arg
1596 has already loaded the register for us. In all other cases,
1597 load the register(s) from memory. */
1600 {
1602 #ifdef BLOCK_REG_PADDING
1603 /* Handle case where we have a value that needs shifting
1604 up to the msb. eg. a QImode value and we're padding
1605 upward on a BYTES_BIG_ENDIAN machine. */
1609 {
1610 rtx x;
1613 /* Assigning REG here rather than a temp makes CALL_FUSAGE
1614 report the whole reg as used. Strictly speaking, the
1615 call only uses SIZE bytes at the msb end, but it doesn't
1616 seem worth generating rtl to say that. */
1623 }
1624 #endif
1625 }
1627 /* If we have pre-computed the values to put in the registers in
1628 the case of non-aligned structures, copy them in now. */
1636 {
1639 /* Check for overlap with already clobbered argument area. */
1642 size))
1645 /* Handle a BLKmode that needs shifting. */
1647 #ifdef BLOCK_REG_PADDING
1649 #else
1650 && BYTES_BIG_ENDIAN
1651 #endif
1652 )
1653 {
1667 }
1668 else
1670 }
1672 /* When a parameter is a block, and perhaps in other cases, it is
1673 possible that it did a load from an argument slot that was
1674 already clobbered. */
1679 /* Handle calls that pass values in multiple non-contiguous
1680 locations. The Irix 6 ABI has examples of this. */
1687 }
1688 }
1689 }
1691 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
1692 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
1693 bytes, then we would need to push some additional bytes to pad the
1694 arguments. So, we compute an adjust to the stack pointer for an
1695 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
1696 bytes. Then, when the arguments are pushed the stack will be perfectly
1697 aligned. ARGS_SIZE->CONSTANT is set to the number of bytes that should
1698 be popped after the call. Returns the adjustment. */
1700 static int
1704 {
1705 /* The number of bytes to pop so that the stack will be
1706 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
1707 HOST_WIDE_INT adjustment;
1708 /* The alignment of the stack after the arguments are pushed, if we
1709 just pushed the arguments without adjust the stack here. */
1712 unadjusted_alignment
1716 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
1717 as possible -- leaving just enough left to cancel out the
1718 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
1719 PENDING_STACK_ADJUST is non-negative, and congruent to
1720 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
1722 /* Begin by trying to pop all the bytes. */
1723 unadjusted_alignment
1724 = (unadjusted_alignment
1727 /* Push enough additional bytes that the stack will be aligned
1728 after the arguments are pushed. */
1730 {
1733 else
1735 }
1737 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
1738 bytes after the call. The right number is the entire
1739 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
1740 by the arguments in the first place. */
1741 args_size->constant
1745 }
1747 /* Scan X expression if it does not dereference any argument slots
1748 we already clobbered by tail call arguments (as noted in stored_args_map
1749 bitmap).
1750 Return nonzero if X expression dereferences such argument slots,
1751 zero otherwise. */
1753 static int
1755 {
1756 RTX_CODE code;
1769 /* Scan all subexpressions. */
1772 {
1774 {
1777 }
1779 {
1783 }
1784 }
1786 }
1788 /* Scan sequence after INSN if it does not dereference any argument slots
1789 we already clobbered by tail call arguments (as noted in stored_args_map
1790 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
1791 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
1792 should be 0). Return nonzero if sequence after INSN dereferences such argument
1793 slots, zero otherwise. */
1795 static int
1797 {
1802 else
1811 {
1812 #ifdef ARGS_GROW_DOWNWARD
1814 #else
1816 #endif
1820 }
1822 }
1824 /* Given that a function returns a value of mode MODE at the most
1825 significant end of hard register VALUE, shift VALUE left or right
1826 as specified by LEFT_P. Return true if some action was needed. */
1828 bool
1830 {
1831 HOST_WIDE_INT shift;
1838 /* Use ashr rather than lshr for right shifts. This is for the benefit
1839 of the MIPS port, which requires SImode values to be sign-extended
1840 when stored in 64-bit registers. */
1845 }
1847 /* Generate all the code for a CALL_EXPR exp
1848 and return an rtx for its value.
1849 Store the value in TARGET (specified as an rtx) if convenient.
1850 If the value is stored in TARGET then TARGET is returned.
1851 If IGNORE is nonzero, then we ignore the value of the function call. */
1853 rtx
1855 {
1856 /* Nonzero if we are currently expanding a call. */
1859 /* RTX for the function to be called. */
1860 rtx funexp;
1861 /* Sequence of insns to perform a normal "call". */
1863 /* Sequence of insns to perform a tail "call". */
1865 /* Data type of the function. */
1866 tree funtype;
1867 tree type_arg_types;
1868 /* Declaration of the function being called,
1869 or 0 if the function is computed (not known by name). */
1871 /* The type of the function being called. */
1872 tree fntype;
1876 /* Register in which non-BLKmode value will be returned,
1877 or 0 if no value or if value is BLKmode. */
1878 rtx valreg;
1879 /* Address where we should return a BLKmode value;
1880 0 if value not BLKmode. */
1882 /* Nonzero if that address is being passed by treating it as
1883 an extra, implicit first parameter. Otherwise,
1884 it is passed by being copied directly into struct_value_rtx. */
1886 /* Holds the value of implicit argument for the struct value. */
1888 /* Size of aggregate value wanted, or zero if none wanted
1889 or if we are using the non-reentrant PCC calling convention
1890 or expecting the value in registers. */
1892 /* Nonzero if called function returns an aggregate in memory PCC style,
1893 by returning the address of where to find it. */
1897 /* Number of actual parameters in this call, including struct value addr. */
1899 /* Number of named args. Args after this are anonymous ones
1900 and they must all go on the stack. */
1902 /* Number of complex actual arguments that need to be split. */
1905 /* Vector of information about each argument.
1906 Arguments are numbered in the order they will be pushed,
1907 not the order they are written. */
1910 /* Total size in bytes of all the stack-parms scanned so far. */
1913 /* Size of arguments before any adjustments (such as rounding). */
1915 /* Data on reg parms scanned so far. */
1916 CUMULATIVE_ARGS args_so_far;
1917 /* Nonzero if a reg parm has been scanned. */
1919 /* Nonzero if this is an indirect function call. */
1921 /* Nonzero if we must avoid push-insns in the args for this call.
1922 If stack space is allocated for register parameters, but not by the
1923 caller, then it is preallocated in the fixed part of the stack frame.
1924 So the entire argument block must then be preallocated (i.e., we
1925 ignore PUSH_ROUNDING in that case). */
1929 /* Size of the stack reserved for parameter registers. */
1932 /* Address of space preallocated for stack parms
1933 (on machines that lack push insns), or 0 if space not preallocated. */
1936 /* Mask of ECF_ flags. */
1938 #ifdef REG_PARM_STACK_SPACE
1939 /* Define the boundary of the register parm stack space that needs to be
1940 saved, if any. */
1943 #endif
1951 /* State variables to track stack modifications. */
1957 /* Some stack pointer alterations we make are performed via
1958 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
1959 which we then also need to save/restore along the way. */
1962 rtx call_fusage;
1966 /* The alignment of the stack, in bits. */
1968 /* The alignment of the stack, in bytes. */
1970 /* The static chain value to use for this call. */
1971 rtx static_chain_value;
1972 /* See if this is "nothrow" function call. */
1976 /* See if we can find a DECL-node for the actual function, and get the
1977 function attributes (flags) from the function decl or type node. */
1980 {
1983 }
1984 else
1985 {
1988 }
1992 /* Warn if this value is an aggregate type,
1993 regardless of which calling convention we are using for it. */
1997 /* If the result of a pure or const function call is ignored (or void),
1998 and none of its arguments are volatile, we can avoid expanding the
1999 call and just evaluate the arguments for side-effects. */
2003 {
2005 tree arg;
2006 call_expr_arg_iterator iter;
2010 {
2013 }
2016 {
2020 }
2021 }
2023 #ifdef REG_PARM_STACK_SPACE
2025 #endif
2030 /* Set up a place to return a structure. */
2032 /* Cater to broken compilers. */
2034 {
2035 /* This call returns a big structure. */
2038 #ifdef PCC_STATIC_STRUCT_RETURN
2039 {
2041 }
2043 {
2048 else
2049 {
2050 /* For variable-sized objects, we must be called with a target
2051 specified. If we were to allocate space on the stack here,
2052 we would have no way of knowing when to free it. */
2058 }
2059 }
2061 }
2063 /* Figure out the amount to which the stack should be aligned. */
2066 {
2070 }
2072 /* Operand 0 is a pointer-to-function; get the type of the function. */
2077 /* Count whether there are actual complex arguments that need to be split
2078 into their real and imaginary parts. Munge the type_arg_types
2079 appropriately here as well. */
2081 {
2082 call_expr_arg_iterator iter;
2083 tree arg;
2085 {
2089 num_complex_actuals++;
2090 }
2092 }
2093 else
2099 /* If struct_value_rtx is 0, it means pass the address
2100 as if it were an extra parameter. Put the argument expression
2101 in structure_value_addr_value. */
2103 {
2104 /* If structure_value_addr is a REG other than
2105 virtual_outgoing_args_rtx, we can use always use it. If it
2106 is not a REG, we must always copy it into a register.
2107 If it is virtual_outgoing_args_rtx, we must copy it to another
2108 register in some cases. */
2110 || (ACCUMULATE_OUTGOING_ARGS
2111 && stack_arg_under_construction
2117 structure_value_addr_value =
2120 }
2122 /* Count the arguments and set NUM_ACTUALS. */
2123 num_actuals =
2126 /* Compute number of named args.
2127 First, do a raw count of the args for INIT_CUMULATIVE_ARGS. */
2130 n_named_args
2132 /* Count the struct value address, if it is passed as a parm. */
2134 else
2135 /* If we know nothing, treat all args as named. */
2138 /* Start updating where the next arg would go.
2140 On some machines (such as the PA) indirect calls have a different
2141 calling convention than normal calls. The fourth argument in
2142 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2143 or not. */
2146 /* Now possibly adjust the number of named args.
2147 Normally, don't include the last named arg if anonymous args follow.
2148 We do include the last named arg if
2149 targetm.calls.strict_argument_naming() returns nonzero.
2150 (If no anonymous args follow, the result of list_length is actually
2151 one too large. This is harmless.)
2153 If targetm.calls.pretend_outgoing_varargs_named() returns
2154 nonzero, and targetm.calls.strict_argument_naming() returns zero,
2155 this machine will be able to place unnamed args that were passed
2156 in registers into the stack. So treat all args as named. This
2157 allows the insns emitting for a specific argument list to be
2158 independent of the function declaration.
2160 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
2161 we do not have any reliable way to pass unnamed args in
2162 registers, so we must force them into memory. */
2166 ;
2169 /* Don't include the last named arg. */
2171 else
2172 /* Treat all args as named. */
2175 /* Make a vector to hold all the information about each arg. */
2179 /* Build up entries in the ARGS array, compute the size of the
2180 arguments into ARGS_SIZE, etc. */
2190 {
2191 /* If this function requires a variable-sized argument list, don't
2192 try to make a cse'able block for this call. We may be able to
2193 do this eventually, but it is too complicated to keep track of
2194 what insns go in the cse'able block and which don't. */
2198 }
2200 /* Now make final decision about preallocating stack space. */
2205 /* If the structure value address will reference the stack pointer, we
2206 must stabilize it. We don't need to do this if we know that we are
2207 not going to adjust the stack pointer in processing this call. */
2212 structure_value_addr))
2217 /* Tail calls can make things harder to debug, and we've traditionally
2218 pushed these optimizations into -O2. Don't try if we're already
2219 expanding a call, as that means we're an argument. Don't try if
2220 there's cleanups, as we know there's code to follow the call. */
2223 || !flag_optimize_sibling_calls
2228 /* Rest of purposes for tail call optimizations to fail. */
2230 #ifdef HAVE_sibcall_epilogue
2231 !HAVE_sibcall_epilogue
2232 #else
2233 1
2234 #endif
2235 || !try_tail_call
2236 /* Doing sibling call optimization needs some work, since
2237 structure_value_addr can be allocated on the stack.
2238 It does not seem worth the effort since few optimizable
2239 sibling calls will return a structure. */
2241 /* Check whether the target is able to optimize the call
2242 into a sibcall. */
2244 /* Functions that do not return exactly once may not be sibcall
2245 optimized. */
2248 /* If the called function is nested in the current one, it might access
2249 some of the caller's arguments, but could clobber them beforehand if
2250 the argument areas are shared. */
2252 /* If this function requires more stack slots than the current
2253 function, we cannot change it into a sibling call.
2254 current_function_pretend_args_size is not part of the
2255 stack allocated by our caller. */
2258 /* If the callee pops its own arguments, then it must pop exactly
2259 the same number of arguments as the current function. */
2263 current_function_args_size))
2267 /* Ensure current function's preferred stack boundary is at least
2268 what we need. We don't have to increase alignment for recursive
2269 functions. */
2278 /* We want to make two insn chains; one for a sibling call, the other
2279 for a normal call. We will select one of the two chains after
2280 initial RTL generation is complete. */
2282 {
2284 /* We want to emit any pending stack adjustments before the tail
2285 recursion "call". That way we know any adjustment after the tail
2286 recursion call can be ignored if we indeed use the tail
2287 call expansion. */
2290 rtx insns;
2294 {
2295 /* State variables we need to save and restore between
2296 iterations. */
2299 }
2302 else
2305 /* Other state variables that we must reinitialize each time
2306 through the loop (that are not initialized by the loop itself). */
2310 /* Start a new sequence for the normal call case.
2312 From this point on, if the sibling call fails, we want to set
2313 sibcall_failure instead of continuing the loop. */
2316 /* Don't let pending stack adjusts add up to too much.
2317 Also, do all pending adjustments now if there is any chance
2318 this might be a call to alloca or if we are expanding a sibling
2319 call sequence or if we are calling a function that is to return
2320 with stack pointer depressed.
2321 Also do the adjustments before a throwing call, otherwise
2322 exception handling can fail; PR 19225. */
2331 /* When calling a const function, we must pop the stack args right away,
2332 so that the pop is deleted or moved with the call. */
2334 NO_DEFER_POP;
2336 /* Precompute any arguments as needed. */
2340 /* Now we are about to start emitting insns that can be deleted
2341 if a libcall is deleted. */
2349 /* Compute the actual size of the argument block required. The variable
2350 and constant sizes must be combined, the size may have to be rounded,
2351 and there may be a minimum required size. When generating a sibcall
2352 pattern, do not round up, since we'll be re-using whatever space our
2353 caller provided. */
2354 unadjusted_args_size
2362 /* The argument block when performing a sibling call is the
2363 incoming argument block. */
2365 {
2367 argblock
2368 #ifdef STACK_GROWS_DOWNWARD
2370 #else
2372 #endif
2375 }
2377 /* If we have no actual push instructions, or shouldn't use them,
2378 make space for all args right now. */
2380 {
2382 {
2387 /* stack_arg_under_construction says whether a stack arg is
2388 being constructed at the old stack level. Pushing the stack
2389 gets a clean outgoing argument block. */
2392 }
2394 }
2395 else
2396 {
2397 /* Note that we must go through the motions of allocating an argument
2398 block even if the size is zero because we may be storing args
2399 in the area reserved for register arguments, which may be part of
2400 the stack frame. */
2404 /* Store the maximum argument space used. It will be pushed by
2405 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
2406 checking). */
2412 {
2414 {
2415 /* Since the stack pointer will never be pushed, it is
2416 possible for the evaluation of a parm to clobber
2417 something we have already written to the stack.
2418 Since most function calls on RISC machines do not use
2419 the stack, this is uncommon, but must work correctly.
2421 Therefore, we save any area of the stack that was already
2422 written and that we are using. Here we set up to do this
2423 by making a new stack usage map from the old one. The
2424 actual save will be done by store_one_arg.
2426 Another approach might be to try to reorder the argument
2427 evaluations to avoid this conflicting stack usage. */
2429 /* Since we will be writing into the entire argument area,
2430 the map must be allocated for its entire size, not just
2431 the part that is the responsibility of the caller. */
2435 #ifdef ARGS_GROW_DOWNWARD
2438 #else
2440 needed);
2441 #endif
2449 initial_highest_arg_in_use);
2453 (highest_outgoing_arg_in_use
2457 /* The address of the outgoing argument list must not be
2458 copied to a register here, because argblock would be left
2459 pointing to the wrong place after the call to
2460 allocate_dynamic_stack_space below. */
2463 }
2464 else
2465 {
2467 {
2468 /* Try to reuse some or all of the pending_stack_adjust
2469 to get this space. */
2470 needed
2471 = (combine_pending_stack_adjustment_and_call
2474 preferred_unit_stack_boundary));
2476 /* combine_pending_stack_adjustment_and_call computes
2477 an adjustment before the arguments are allocated.
2478 Account for them and see whether or not the stack
2479 needs to go up or down. */
2483 {
2484 /* We're releasing stack space. */
2485 /* ??? We can avoid any adjustment at all if we're
2486 already aligned. FIXME. */
2490 }
2491 else
2492 /* We need to allocate space. We'll do that in
2493 push_block below. */
2495 }
2497 /* Special case this because overhead of `push_block' in
2498 this case is non-trivial. */
2501 else
2502 {
2504 #ifdef ARGS_GROW_DOWNWARD
2506 #endif
2507 }
2509 /* We only really need to call `copy_to_reg' in the case
2510 where push insns are going to be used to pass ARGBLOCK
2511 to a function call in ARGS. In that case, the stack
2512 pointer changes value from the allocation point to the
2513 call point, and hence the value of
2514 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
2515 as well always do it. */
2517 }
2518 }
2519 }
2522 {
2523 /* The save/restore code in store_one_arg handles all
2524 cases except one: a constructor call (including a C
2525 function returning a BLKmode struct) to initialize
2526 an argument. */
2528 {
2529 rtx push_size
2534 {
2536 NULL_RTX);
2540 /* stack_arg_under_construction says whether a stack
2541 arg is being constructed at the old stack level.
2542 Pushing the stack gets a clean outgoing argument
2543 block. */
2544 old_stack_arg_under_construction
2547 /* Make a new map for the new argument list. */
2553 }
2555 BITS_PER_UNIT);
2556 }
2558 /* If argument evaluation might modify the stack pointer,
2559 copy the address of the argument list to a register. */
2562 {
2565 }
2566 }
2570 /* If we push args individually in reverse order, perform stack alignment
2571 before the first push (the last arg). */
2574 {
2575 /* When the stack adjustment is pending, we get better code
2576 by combining the adjustments. */
2580 {
2581 pending_stack_adjust
2582 = (combine_pending_stack_adjustment_and_call
2585 preferred_unit_stack_boundary));
2587 }
2591 }
2592 /* Now that the stack is properly aligned, pops can't safely
2593 be deferred during the evaluation of the arguments. */
2594 NO_DEFER_POP;
2598 /* Figure out the register where the value, if any, will come back. */
2602 {
2606 else
2610 /* If VALREG is a PARALLEL whose first member has a zero
2611 offset, use that. This is for targets such as m68k that
2612 return the same value in multiple places. */
2614 {
2621 }
2622 }
2624 /* Precompute all register parameters. It isn't safe to compute anything
2625 once we have started filling any specific hard regs. */
2630 else
2633 #ifdef REG_PARM_STACK_SPACE
2634 /* Save the fixed argument area if it's part of the caller's frame and
2635 is clobbered by argument setup for this call. */
2639 #endif
2641 /* Now store (and compute if necessary) all non-register parms.
2642 These come before register parms, since they can require block-moves,
2643 which could clobber the registers used for register parms.
2644 Parms which have partial registers are not stored here,
2645 but we do preallocate space here if they want that. */
2649 {
2654 reg_parm_stack_space)
2666 call_fusage);
2667 }
2669 /* If we have a parm that is passed in registers but not in memory
2670 and whose alignment does not permit a direct copy into registers,
2671 make a group of pseudos that correspond to each register that we
2672 will later fill. */
2676 /* Now store any partially-in-registers parm.
2677 This is the last place a block-move can happen. */
2681 {
2686 reg_parm_stack_space)
2691 }
2693 /* If we pushed args in forward order, perform stack alignment
2694 after pushing the last arg. */
2699 /* If register arguments require space on the stack and stack space
2700 was not preallocated, allocate stack space here for arguments
2701 passed in registers. */
2706 /* Pass the function the address in which to return a
2707 structure value. */
2709 {
2710 structure_value_addr
2715 NULL_RTX)));
2719 }
2727 /* Save a pointer to the last insn before the call, so that we can
2728 later safely search backwards to find the CALL_INSN. */
2731 /* Set up next argument register. For sibling calls on machines
2732 with register windows this should be the incoming register. */
2733 #ifdef FUNCTION_INCOMING_ARG
2737 else
2738 #endif
2742 /* All arguments and registers used for the call must be set up by
2743 now! */
2745 /* Stack must be properly aligned now. */
2749 /* Generate the actual call instruction. */
2755 /* If a non-BLKmode value is returned at the most significant end
2756 of a register, shift the register right by the appropriate amount
2757 and update VALREG accordingly. BLKmode values are handled by the
2758 group load/store machinery below. */
2760 && !pcc_struct_value
2763 {
2767 }
2769 /* If call is cse'able, make appropriate pair of reg-notes around it.
2770 Test valreg so we don't crash; may safely ignore `const'
2771 if return type is void. Disable for PARALLEL return values, because
2772 we have no way to move such values into a pseudo register. */
2774 {
2775 rtx insns;
2776 rtx insn;
2781 /* Expansion of block moves possibly introduced a loop that may
2782 not appear inside libcall block. */
2788 {
2791 }
2792 else
2793 {
2797 /* Mark the return value as a pointer if needed. */
2804 && fndecl
2812 else
2813 {
2814 /* Construct an "equal form" for the value which
2815 mentions all the arguments in order as well as
2816 the function name. */
2827 note);
2828 }
2832 }
2833 }
2835 {
2839 /* The return value from a malloc-like function is a pointer. */
2845 /* The return value from a malloc-like function can not alias
2846 anything else. */
2851 /* Write out the sequence. */
2856 }
2858 /* For calls to `setjmp', etc., inform flow.c it should complain
2859 if nonvolatile values are live. For functions that cannot return,
2860 inform flow that control does not fall through. */
2863 {
2864 /* The barrier must be emitted
2865 immediately after the CALL_INSN. Some ports emit more
2866 than just a CALL_INSN above, so we must search for it here. */
2870 {
2872 /* There was no CALL_INSN? */
2874 }
2878 /* Stack adjustments after a noreturn call are dead code.
2879 However when NO_DEFER_POP is in effect, we must preserve
2880 stack_pointer_delta. */
2882 {
2885 }
2886 }
2888 /* If value type not void, return an rtx for the value. */
2894 {
2896 {
2897 target
2900 structure_value_addr));
2902 }
2903 }
2905 {
2906 /* This is the special C++ case where we need to
2907 know what the true target was. We take care to
2908 never use this value more than once in one expression. */
2912 }
2913 /* Handle calls that return values in multiple non-contiguous locations.
2914 The Irix 6 ABI has examples of this. */
2916 {
2918 {
2919 /* This will only be assigned once, so it can be readonly. */
2925 }
2931 /* We can not support sibling calls for this case. */
2933 }
2937 {
2940 /* We have to copy a return value in a CLASS_LIKELY_SPILLED hard
2941 reg to a plain register. */
2948 /* If TARGET is a MEM in the argument area, and we have
2949 saved part of the argument area, then we can't store
2950 directly into TARGET as it may get overwritten when we
2951 restore the argument save area below. Don't work too
2952 hard though and simply force TARGET to a register if it
2953 is a MEM; the optimizer is quite likely to sort it out. */
2957 {
2960 }
2964 else
2965 {
2966 /* TARGET and VALREG cannot be equal at this point
2967 because the latter would not have
2968 REG_FUNCTION_VALUE_P true, while the former would if
2969 it were referring to the same register.
2971 If they refer to the same register, this move will be
2972 a no-op, except when function inlining is being
2973 done. */
2976 /* If we are setting a MEM, this code must be executed.
2977 Since it is emitted after the call insn, sibcall
2978 optimization cannot be performed in that case. */
2981 }
2982 }
2984 {
2987 /* We can not support sibling calls for this case. */
2989 }
2990 else
2994 {
2995 /* If we promoted this return value, make the proper SUBREG.
2996 TARGET might be const0_rtx here, so be careful. */
3000 {
3007 /* If we don't promote as expected, something is wrong. */
3013 {
3020 }
3024 }
3025 }
3027 /* If size of args is variable or this was a constructor call for a stack
3028 argument, restore saved stack-pointer value. */
3031 {
3040 }
3042 {
3043 #ifdef REG_PARM_STACK_SPACE
3047 #endif
3049 /* If we saved any argument areas, restore them. */
3052 {
3054 rtx stack_area
3061 else
3064 BLOCK_OP_CALL_PARM);
3065 }
3069 }
3071 /* If this was alloca, record the new stack level for nonlocal gotos.
3072 Check for the handler slots since we might not have a save area
3073 for non-local gotos. */
3078 /* Free up storage we no longer need. */
3087 {
3090 /* Restore the pending stack adjustment now that we have
3091 finished generating the sibling call sequence. */
3096 /* Prepare arg structure for next iteration. */
3098 {
3102 }
3105 }
3106 else
3107 {
3110 /* Verify that we've deallocated all the stack we used. */
3112 || (old_stack_allocated
3114 }
3116 /* If something prevents making this a sibling call,
3117 zero out the sequence. */
3120 else
3122 }
3124 /* If tail call production succeeded, we need to remove REG_EQUIV notes on
3125 arguments too, as argument area is now clobbered by the call. */
3127 {
3130 }
3131 else
3134 currently_expanding_call--;
3136 /* If this function returns with the stack pointer depressed, ensure
3137 this block saves and restores the stack pointer, show it was
3138 changed, and adjust for any outgoing arg space. */
3140 {
3144 }
3150 }
3152 /* A sibling call sequence invalidates any REG_EQUIV notes made for
3153 this function's incoming arguments.
3155 At the start of RTL generation we know the only REG_EQUIV notes
3156 in the rtl chain are those for incoming arguments, so we can look
3157 for REG_EQUIV notes between the start of the function and the
3158 NOTE_INSN_FUNCTION_BEG.
3160 This is (slight) overkill. We could keep track of the highest
3161 argument we clobber and be more selective in removing notes, but it
3162 does not seem to be worth the effort. */
3164 void
3166 {
3167 rtx insn;
3170 {
3171 rtx note;
3173 /* There are never REG_EQUIV notes for the incoming arguments
3174 after the NOTE_INSN_FUNCTION_BEG note, so stop if we see it. */
3184 }
3185 }
3187 /* Traverse a list of TYPES and expand all complex types into their
3188 components. */
3189 static tree
3191 {
3192 tree p;
3194 /* Before allocating memory, check for the common case of no complex. */
3196 {
3201 }
3204 found:
3208 {
3213 {
3216 /* Rewrite complex type with component type. */
3220 /* Add another component type for the imaginary part. */
3225 /* Skip the newly created node. */
3227 }
3228 }
3231 }
3232 \f
3233 /* Output a library call to function FUN (a SYMBOL_REF rtx).
3234 The RETVAL parameter specifies whether return value needs to be saved, other
3235 parameters are documented in the emit_library_call function below. */
3237 static rtx
3241 {
3242 /* Total size in bytes of all the stack-parms scanned so far. */
3244 /* Size of arguments before any adjustments (such as rounding). */
3247 rtx fun;
3251 CUMULATIVE_ARGS args_so_far;
3252 struct arg
3253 {
3254 rtx value;
3256 rtx reg;
3259 rtx save_area;
3260 };
3265 rtx valreg;
3271 rtx before_call;
3274 #ifdef REG_PARM_STACK_SPACE
3275 /* Define the boundary of the register parm stack space that needs to be
3276 save, if any. */
3279 #endif
3281 /* Size of the stack reserved for parameter registers. */
3288 #ifdef REG_PARM_STACK_SPACE
3290 #endif
3292 /* By default, library functions can not throw. */
3296 {
3320 }
3323 /* Ensure current function's preferred stack boundary is at least
3324 what we need. */
3328 /* If this kind of value comes back in memory,
3329 decide where in memory it should come back. */
3331 {
3334 {
3335 #ifdef PCC_STATIC_STRUCT_RETURN
3336 rtx pointer_reg
3346 else
3348 #endif
3349 /* This call returns a big structure. */
3351 }
3352 }
3353 else
3356 /* ??? Unfinished: must pass the memory address as an argument. */
3358 /* Copy all the libcall-arguments out of the varargs data
3359 and into a vector ARGVEC.
3361 Compute how to pass each argument. We only support a very small subset
3362 of the full argument passing conventions to limit complexity here since
3363 library functions shouldn't have many args. */
3368 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
3370 #else
3372 #endif
3379 /* Now we are about to start emitting insns that can be deleted
3380 if a libcall is deleted. */
3386 /* If there's a structure value address to be passed,
3387 either pass it in the special place, or pass it as an extra argument. */
3389 {
3392 nargs++;
3394 /* Make sure it is a reasonable operand for a move or push insn. */
3408 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3410 #else
3412 #endif
3421 count++;
3422 }
3425 {
3429 /* We cannot convert the arg value to the mode the library wants here;
3430 must do it earlier where we know the signedness of the arg. */
3434 /* Make sure it is a reasonable operand for a move or push insn. */
3440 {
3441 rtx slot;
3442 int must_copy
3445 /* loop.c won't look at CALL_INSN_FUNCTION_USAGE of const/pure
3446 functions, so we have to pretend this isn't such a function. */
3448 {
3452 }
3455 /* If this was a CONST function, it is now PURE since
3456 it now reads memory. */
3458 {
3461 }
3465 else
3466 {
3470 }
3474 call_fusage);
3478 slot),
3479 call_fusage);
3483 }
3494 #ifdef STACK_PARMS_IN_REG_PARM_AREA
3496 #else
3498 #endif
3509 }
3511 /* If this machine requires an external definition for library
3512 functions, write one out. */
3517 + stack_pointer_delta
3519 / STACK_BYTES
3524 reg_parm_stack_space);
3533 {
3534 /* Since the stack pointer will never be pushed, it is possible for
3535 the evaluation of a parm to clobber something we have already
3536 written to the stack. Since most function calls on RISC machines
3537 do not use the stack, this is uncommon, but must work correctly.
3539 Therefore, we save any area of the stack that was already written
3540 and that we are using. Here we set up to do this by making a new
3541 stack usage map from the old one.
3543 Another approach might be to try to reorder the argument
3544 evaluations to avoid this conflicting stack usage. */
3548 /* Since we will be writing into the entire argument area, the
3549 map must be allocated for its entire size, not just the part that
3550 is the responsibility of the caller. */
3554 #ifdef ARGS_GROW_DOWNWARD
3557 #else
3559 needed);
3560 #endif
3566 initial_highest_arg_in_use);
3573 /* We must be careful to use virtual regs before they're instantiated,
3574 and real regs afterwards. Loop optimization, for example, can create
3575 new libcalls after we've instantiated the virtual regs, and if we
3576 use virtuals anyway, they won't match the rtl patterns. */
3580 else
3582 }
3583 else
3584 {
3587 }
3589 /* If we push args individually in reverse order, perform stack alignment
3590 before the first push (the last arg). */
3596 {
3599 }
3600 else
3601 {
3604 }
3606 #ifdef REG_PARM_STACK_SPACE
3608 {
3609 /* The argument list is the property of the called routine and it
3610 may clobber it. If the fixed area has been used for previous
3611 parameters, we must save and restore it. */
3614 }
3615 #endif
3617 /* Push the args that need to be pushed. */
3619 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
3620 are to be pushed. */
3622 {
3630 {
3632 {
3633 /* If this is being stored into a pre-allocated, fixed-size,
3634 stack area, save any previous data at that location. */
3636 #ifdef ARGS_GROW_DOWNWARD
3637 /* stack_slot is negative, but we want to index stack_usage_map
3638 with positive values. */
3641 #else
3644 #endif
3647 /* Don't worry about things in the fixed argument area;
3648 it has already been saved. */
3652 i++;
3655 {
3656 /* We need to make a save area. */
3657 unsigned int size
3659 enum machine_mode save_mode
3661 rtx adr
3664 rtx stack_area
3668 {
3675 stack_area,
3677 BLOCK_OP_CALL_PARM);
3678 }
3679 else
3680 {
3684 }
3685 }
3686 }
3691 reg_parm_stack_space,
3694 /* Now mark the segment we just used. */
3699 NO_DEFER_POP;
3702 {
3703 rtx use;
3705 /* Indicate argument access so that alias.c knows that these
3706 values are live. */
3710 else
3711 /* When arguments are pushed, trying to tell alias.c where
3712 exactly this argument is won't work, because the
3713 auto-increment causes confusion. So we merely indicate
3714 that we access something with a known mode somewhere on
3715 the stack. */
3721 }
3722 }
3723 }
3725 /* If we pushed args in forward order, perform stack alignment
3726 after pushing the last arg. */
3733 else
3738 /* Now load any reg parms into their regs. */
3740 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
3741 are to be pushed. */
3743 {
3749 /* Handle calls that pass values in multiple non-contiguous
3750 locations. The PA64 has examples of this for library calls. */
3756 NO_DEFER_POP;
3757 }
3759 /* Any regs containing parms remain in use through the call. */
3761 {
3766 {
3769 {
3774 }
3775 else
3777 }
3778 }
3780 /* Pass the function the address in which to return a structure value. */
3782 {
3786 NULL_RTX)));
3789 }
3791 /* Don't allow popping to be deferred, since then
3792 cse'ing of library calls could delete a call and leave the pop. */
3793 NO_DEFER_POP;
3797 /* Stack must be properly aligned now. */
3803 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
3804 will set inhibit_defer_pop to that value. */
3805 /* The return type is needed to decide how many bytes the function pops.
3806 Signedness plays no role in that, so for simplicity, we pretend it's
3807 always signed. We also assume that the list of arguments passed has
3808 no impact, so we pretend it is unknown. */
3814 struct_value_size,
3816 valreg,
3819 /* For calls to `setjmp', etc., inform flow.c it should complain
3820 if nonvolatile values are live. For functions that cannot return,
3821 inform flow that control does not fall through. */
3824 {
3825 /* The barrier note must be emitted
3826 immediately after the CALL_INSN. Some ports emit more than
3827 just a CALL_INSN above, so we must search for it here. */
3831 {
3833 /* There was no CALL_INSN? */
3835 }
3838 }
3840 /* Now restore inhibit_defer_pop to its actual original value. */
3841 OK_DEFER_POP;
3843 /* If call is cse'able, make appropriate pair of reg-notes around it.
3844 Test valreg so we don't crash; may safely ignore `const'
3845 if return type is void. Disable for PARALLEL return values, because
3846 we have no way to move such values into a pseudo register. */
3848 {
3849 rtx insns;
3852 {
3856 }
3857 else
3858 {
3860 rtx temp;
3864 {
3869 }
3873 /* Construct an "equal form" for the value which mentions all the
3874 arguments in order as well as the function name. */
3887 note);
3892 }
3893 }
3896 /* Copy the value to the right place. */
3898 {
3900 {
3905 }
3907 {
3911 }
3912 else
3913 {
3914 /* Convert to the proper mode if PROMOTE_MODE has been active. */
3916 {
3924 }
3928 else
3930 }
3931 }
3934 {
3935 #ifdef REG_PARM_STACK_SPACE
3939 #endif
3941 /* If we saved any argument areas, restore them. */
3944 {
3955 BLOCK_OP_CALL_PARM);
3956 else
3958 }
3962 }
3969 }
3970 \f
3971 /* Output a library call to function FUN (a SYMBOL_REF rtx)
3972 (emitting the queue unless NO_QUEUE is nonzero),
3973 for a value of mode OUTMODE,
3974 with NARGS different arguments, passed as alternating rtx values
3975 and machine_modes to convert them to.
3977 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for `const'
3978 calls, LCT_PURE for `pure' calls, LCT_CONST_MAKE_BLOCK for `const' calls
3979 which should be enclosed in REG_LIBCALL/REG_RETVAL notes,
3980 LCT_PURE_MAKE_BLOCK for `purep' calls which should be enclosed in
3981 REG_LIBCALL/REG_RETVAL notes with extra (use (memory (scratch)),
3982 or other LCT_ value for other types of library calls. */
3984 void
3987 {
3993 }
3994 \f
3995 /* Like emit_library_call except that an extra argument, VALUE,
3996 comes second and says where to store the result.
3997 (If VALUE is zero, this function chooses a convenient way
3998 to return the value.
4000 This function returns an rtx for where the value is to be found.
4001 If VALUE is nonzero, VALUE is returned. */
4003 rtx
4007 {
4008 rtx result;
4017 }
4018 \f
4019 /* Store a single argument for a function call
4020 into the register or memory area where it must be passed.
4021 *ARG describes the argument value and where to pass it.
4023 ARGBLOCK is the address of the stack-block for all the arguments,
4024 or 0 on a machine where arguments are pushed individually.
4026 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4027 so must be careful about how the stack is used.
4029 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4030 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4031 that we need not worry about saving and restoring the stack.
4033 FNDECL is the declaration of the function we are calling.
4035 Return nonzero if this arg should cause sibcall failure,
4036 zero otherwise. */
4038 static int
4041 {
4052 /* Push a new temporary level for any temporaries we make for
4053 this argument. */
4057 {
4058 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4059 save any previous data at that location. */
4061 {
4062 #ifdef ARGS_GROW_DOWNWARD
4063 /* stack_slot is negative, but we want to index stack_usage_map
4064 with positive values. */
4067 else
4071 #else
4074 else
4078 #endif
4081 /* Don't worry about things in the fixed argument area;
4082 it has already been saved. */
4086 i++;
4089 {
4090 /* We need to make a save area. */
4097 {
4106 BLOCK_OP_CALL_PARM);
4107 }
4108 else
4109 {
4112 }
4113 }
4114 }
4115 }
4117 /* If this isn't going to be placed on both the stack and in registers,
4118 set up the register and number of words. */
4120 {
4123 else
4126 }
4128 /* Being passed entirely in a register. We shouldn't be called in
4129 this case. */
4132 /* If this arg needs special alignment, don't load the registers
4133 here. */
4137 /* If this is being passed partially in a register, we can't evaluate
4138 it directly into its stack slot. Otherwise, we can. */
4140 {
4141 /* stack_arg_under_construction is nonzero if a function argument is
4142 being evaluated directly into the outgoing argument list and
4143 expand_call must take special action to preserve the argument list
4144 if it is called recursively.
4146 For scalar function arguments stack_usage_map is sufficient to
4147 determine which stack slots must be saved and restored. Scalar
4148 arguments in general have pass_on_stack == 0.
4150 If this argument is initialized by a function which takes the
4151 address of the argument (a C++ constructor or a C function
4152 returning a BLKmode structure), then stack_usage_map is
4153 insufficient and expand_call must push the stack around the
4154 function call. Such arguments have pass_on_stack == 1.
4156 Note that it is always safe to set stack_arg_under_construction,
4157 but this generates suboptimal code if set when not needed. */
4160 stack_arg_under_construction++;
4163 (partial
4168 /* If we are promoting object (or for any other reason) the mode
4169 doesn't agree, convert the mode. */
4176 stack_arg_under_construction--;
4177 }
4179 /* Check for overlap with already clobbered argument area. */
4186 /* Don't allow anything left on stack from computation
4187 of argument to alloca. */
4192 /* If the value is already in the stack slot, we are done. */
4193 ;
4195 {
4199 /* Argument is a scalar, not entirely passed in registers.
4200 (If part is passed in registers, arg->partial says how much
4201 and emit_push_insn will take care of putting it there.)
4203 Push it, and if its size is less than the
4204 amount of space allocated to it,
4205 also bump stack pointer by the additional space.
4206 Note that in C the default argument promotions
4207 will prevent such mismatches. */
4210 /* Compute how much space the push instruction will push.
4211 On many machines, pushing a byte will advance the stack
4212 pointer by a halfword. */
4213 #ifdef PUSH_ROUNDING
4215 #endif
4218 /* Compute how much space the argument should get:
4219 round up to a multiple of the alignment for arguments. */
4225 /* Compute the alignment of the pushed argument. */
4228 {
4231 {
4234 }
4235 }
4237 /* This isn't already where we want it on the stack, so put it there.
4238 This can either be done with push or copy insns. */
4244 /* Unless this is a partially-in-register argument, the argument is now
4245 in the stack. */
4248 }
4249 else
4250 {
4251 /* BLKmode, at least partly to be pushed. */
4255 rtx size_rtx;
4257 /* Pushing a nonscalar.
4258 If part is passed in registers, PARTIAL says how much
4259 and emit_push_insn will take care of putting it there. */
4261 /* Round its size up to a multiple
4262 of the allocation unit for arguments. */
4265 {
4268 }
4269 else
4270 {
4271 /* PUSH_ROUNDING has no effect on us, because emit_push_insn
4272 for BLKmode is careful to avoid it. */
4278 }
4282 /* When an argument is padded down, the block is aligned to
4283 PARM_BOUNDARY, but the actual argument isn't. */
4285 {
4289 {
4292 }
4293 }
4296 {
4297 /* emit_push_insn might not work properly if arg->value and
4298 argblock + arg->locate.offset areas overlap. */
4305 current_function_internal_arg_pointer
4307 {
4311 /* expand_call should ensure this. */
4316 {
4319 }
4321 {
4324 }
4325 }
4326 }
4333 /* Unless this is a partially-in-register argument, the argument is now
4334 in the stack.
4336 ??? Unlike the case above, in which we want the actual
4337 address of the data, so that we can load it directly into a
4338 register, here we want the address of the stack slot, so that
4339 it's properly aligned for word-by-word copying or something
4340 like that. It's not clear that this is always correct. */
4343 }
4346 {
4348 arg->parallel_value
4351 }
4353 /* Mark all slots this store used. */
4359 /* Once we have pushed something, pops can't safely
4360 be deferred during the rest of the arguments. */
4361 NO_DEFER_POP;
4363 /* Free any temporary slots made in processing this argument. Show
4364 that we might have taken the address of something and pushed that
4365 as an operand. */
4371 }
4373 /* Nonzero if we do not know how to pass TYPE solely in registers. */
4375 bool
4377 tree type)
4378 {
4382 /* If the type has variable size... */
4386 /* If the type is marked as addressable (it is required
4387 to be constructed into the stack)... */
4392 }
4394 /* Another version of the TARGET_MUST_PASS_IN_STACK hook. This one
4395 takes trailing padding of a structure into account. */
4396 /* ??? Should be able to merge these two by examining BLOCK_REG_PADDING. */
4398 bool
4400 {
4404 /* If the type has variable size... */
4408 /* If the type is marked as addressable (it is required
4409 to be constructed into the stack)... */
4413 /* If the padding and mode of the type is such that a copy into
4414 a register would put it into the wrong part of the register. */
4422 }