| blob | e50d3fc3b62080b0e59630c247f7a55aec17eb56 |
1 /* Convert function calls to rtl insns, for GNU C compiler.
2 Copyright (C) 1989-2021 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
63 /* Like PREFERRED_STACK_BOUNDARY but in units of bytes, not bits. */
64 #define STACK_BYTES (PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT)
66 /* Data structure and subroutines used within expand_call. */
68 struct arg_data
69 {
70 /* Tree node for this argument. */
71 tree tree_value;
72 /* Mode for value; TYPE_MODE unless promoted. */
73 machine_mode mode;
74 /* Current RTL value for argument, or 0 if it isn't precomputed. */
75 rtx value;
76 /* Initially-compute RTL value for argument; only for const functions. */
77 rtx initial_value;
78 /* Register to pass this argument in, 0 if passed on stack, or an
79 PARALLEL if the arg is to be copied into multiple non-contiguous
80 registers. */
81 rtx reg;
82 /* Register to pass this argument in when generating tail call sequence.
83 This is not the same register as for normal calls on machines with
84 register windows. */
85 rtx tail_call_reg;
86 /* If REG is a PARALLEL, this is a copy of VALUE pulled into the correct
87 form for emit_group_move. */
88 rtx parallel_value;
89 /* If REG was promoted from the actual mode of the argument expression,
90 indicates whether the promotion is sign- or zero-extended. */
92 /* Number of bytes to put in registers. 0 means put the whole arg
93 in registers. Also 0 if not passed in registers. */
95 /* Nonzero if argument must be passed on stack.
96 Note that some arguments may be passed on the stack
97 even though pass_on_stack is zero, just because FUNCTION_ARG says so.
98 pass_on_stack identifies arguments that *cannot* go in registers. */
100 /* Some fields packaged up for locate_and_pad_parm. */
102 /* Location on the stack at which parameter should be stored. The store
103 has already been done if STACK == VALUE. */
104 rtx stack;
105 /* Location on the stack of the start of this argument slot. This can
106 differ from STACK if this arg pads downward. This location is known
107 to be aligned to TARGET_FUNCTION_ARG_BOUNDARY. */
108 rtx stack_slot;
109 /* Place that this stack area has been saved, if needed. */
110 rtx save_area;
111 /* If an argument's alignment does not permit direct copying into registers,
112 copy in smaller-sized pieces into pseudos. These are stored in a
113 block pointed to by this field. The next field says how many
114 word-sized pseudos we made. */
117 };
119 /* A vector of one char per byte of stack space. A byte if nonzero if
120 the corresponding stack location has been used.
121 This vector is used to prevent a function call within an argument from
122 clobbering any stack already set up. */
125 /* Size of STACK_USAGE_MAP. */
128 /* Assume that any stack location at this byte index is used,
129 without checking the contents of stack_usage_map. */
132 /* A bitmap of virtual-incoming stack space. Bit is set if the corresponding
133 stack location's tail call argument has been already stored into the stack.
134 This bitmap is used to prevent sibling call optimization if function tries
135 to use parent's incoming argument slots when they have been already
136 overwritten with tail call arguments. */
139 /* Assume that any virtual-incoming location at this byte index has been
140 stored, without checking the contents of stored_args_map. */
143 /* stack_arg_under_construction is nonzero when an argument may be
144 initialized with a constructor call (including a C function that
145 returns a BLKmode struct) and expand_call must take special action
146 to make sure the object being constructed does not overlap the
147 argument list for the constructor call. */
166 #ifdef REG_PARM_STACK_SPACE
169 #endif
170 \f
171 /* Return true if bytes [LOWER_BOUND, UPPER_BOUND) of the outgoing
172 stack region might already be in use. */
174 static bool
177 {
186 /* Don't worry about things in the fixed argument area;
187 it has already been saved. */
194 }
196 /* Record that bytes [LOWER_BOUND, UPPER_BOUND) of the outgoing
197 stack region are now in use. */
199 static void
201 {
207 else
209 }
211 /* Force FUNEXP into a form suitable for the address of a CALL,
212 and return that as an rtx. Also load the static chain register
213 if FNDECL is a nested function.
215 CALL_FUSAGE points to a variable holding the prospective
216 CALL_INSN_FUNCTION_USAGE information. */
218 rtx
221 {
222 /* Make a valid memory address and copy constants through pseudo-regs,
223 but not for a constant address if -fno-function-cse. */
225 {
226 /* If it's an indirect call by descriptor, generate code to perform
227 runtime identification of the pointer and load the descriptor. */
229 {
234 fndecl_or_type
236 fndecl_or_type);
243 /* Avoid long live ranges around function calls. */
249 /* Emit the runtime identification pattern. */
252 call_lab);
254 /* Statically predict the branch to very likely taken. */
259 /* Load the descriptor. */
268 POINTER_SIZE / BITS_PER_UNIT
277 {
280 }
282 /* Make sure we're not going to be overwritten below. */
284 }
286 /* If we are using registers for parameters, force the
287 function address into a register now. */
288 funexp = ((reg_parm_seen
292 }
293 else
294 {
295 /* funexp could be a SYMBOL_REF represents a function pointer which is
296 of ptr_mode. In this case, it should be converted into address mode
297 to be a valid address for memory rtx pattern. See PR 64971. */
302 {
305 }
306 }
311 {
312 rtx chain;
319 {
322 }
323 }
326 }
328 /* Generate instructions to call function FUNEXP,
329 and optionally pop the results.
330 The CALL_INSN is the first insn generated.
332 FNDECL is the declaration node of the function. This is given to the
333 hook TARGET_RETURN_POPS_ARGS to determine whether this function pops
334 its own args.
336 FUNTYPE is the data type of the function. This is given to the hook
337 TARGET_RETURN_POPS_ARGS to determine whether this function pops its
338 own args. We used to allow an identifier for library functions, but
339 that doesn't work when the return type is an aggregate type and the
340 calling convention says that the pointer to this aggregate is to be
341 popped by the callee.
343 STACK_SIZE is the number of bytes of arguments on the stack,
344 ROUNDED_STACK_SIZE is that number rounded up to
345 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
346 both to put into the call insn and to generate explicit popping
347 code if necessary.
349 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
350 It is zero if this call doesn't want a structure value.
352 NEXT_ARG_REG is the rtx that results from executing
353 targetm.calls.function_arg (&args_so_far,
354 function_arg_info::end_marker ());
355 just after all the args have had their registers assigned.
356 This could be whatever you like, but normally it is the first
357 arg-register beyond those used for args in this call,
358 or 0 if all the arg-registers are used in this call.
359 It is passed on to `gen_call' so you can put this info in the call insn.
361 VALREG is a hard register in which a value is returned,
362 or 0 if the call does not return a value.
364 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
365 the args to this call were processed.
366 We restore `inhibit_defer_pop' to that value.
368 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
369 denote registers used by the called function. */
371 static void
373 tree funtype ATTRIBUTE_UNUSED,
374 poly_int64 stack_size ATTRIBUTE_UNUSED,
375 poly_int64 rounded_stack_size,
376 poly_int64 struct_value_size ATTRIBUTE_UNUSED,
379 cumulative_args_t args_so_far ATTRIBUTE_UNUSED)
380 {
386 /* Sibling call patterns never pop arguments (no sibcall(_value)_pop
387 patterns exist). Any popping that the callee does on return will
388 be from our caller's frame rather than ours. */
390 {
393 #ifdef CALL_POPS_ARGS
395 #endif
396 }
398 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
399 and we don't want to load it into a register as an optimization,
400 because prepare_call_address already did it if it should be done. */
406 {
409 /* Although a built-in FUNCTION_DECL and its non-__builtin
410 counterpart compare equal and get a shared mem_attrs, they
411 produce different dump output in compare-debug compilations,
412 if an entry gets garbage collected in one compilation, then
413 adds a different (but equivalent) entry, while the other
414 doesn't run the garbage collector at the same spot and then
415 shares the mem_attr with the equivalent entry. */
417 {
421 }
424 }
429 {
432 rounded_stack_size_rtx,
434 else
436 next_arg_reg,
438 }
439 /* If the target has "call" or "call_value" insns, then prefer them
440 if no arguments are actually popped. If the target does not have
441 "call" or "call_value" insns, then we must use the popping versions
442 even if the call has no arguments to pop. */
444 || !(valreg
447 {
450 /* If this subroutine pops its own args, record that in the call insn
451 if possible, for the sake of frame pointer elimination. */
455 rounded_stack_size_rtx,
457 else
462 }
463 else
464 {
468 else
471 }
474 /* Find the call we just emitted. */
477 /* Some target create a fresh MEM instead of reusing the one provided
478 above. Set its MEM_EXPR. */
485 /* Put the register usage information there. */
488 /* If this is a const call, then set the insn's unchanging bit. */
492 /* If this is a pure call, then set the insn's unchanging bit. */
496 /* If this is a const call, then set the insn's unchanging bit. */
500 /* Create a nothrow REG_EH_REGION note, if needed. */
507 {
510 }
514 /* Restore this now, so that we do defer pops for this call's args
515 if the context of the call as a whole permits. */
519 {
531 /* If popup is needed, stack realign must use DRAP */
534 }
535 /* For noreturn calls when not accumulating outgoing args force
536 REG_ARGS_SIZE note to prevent crossjumping of calls with different
537 args sizes. */
542 {
543 /* If returning from the subroutine does not automatically pop the args,
544 we need an instruction to pop them sooner or later.
545 Perhaps do it now; perhaps just record how much space to pop later.
547 If returning from the subroutine does pop the args, indicate that the
548 stack pointer will be changed. */
551 {
553 /* Just pretend we did the pop. */
558 else
560 }
561 }
562 /* When we accumulate outgoing args, we must avoid any stack manipulations.
563 Restore the stack pointer to its original value now. Usually
564 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
565 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
566 popping variants of functions exist as well.
568 ??? We may optimize similar to defer_pop above, but it is
569 probably not worthwhile.
571 ??? It will be worthwhile to enable combine_stack_adjustments even for
572 such machines. */
575 }
577 /* Determine if the function identified by FNDECL is one with
578 special properties we wish to know about. Modify FLAGS accordingly.
580 For example, if the function might return more than one time (setjmp), then
581 set ECF_RETURNS_TWICE.
583 Set ECF_MAY_BE_ALLOCA for any memory allocation function that might allocate
584 space from the stack such as alloca. */
586 static int
588 {
593 {
597 /* We assume that alloca will always be called by name. It
598 makes no sense to pass it as a pointer-to-function to
599 anything that does not understand its behavior. */
605 /* Disregard prefix _ or __. */
607 {
610 else
612 }
614 /* ECF_RETURNS_TWICE is safe even for -ffreestanding. */
621 }
628 }
630 /* Return fnspec for DECL. */
632 static attr_fnspec
634 {
635 tree attr;
638 {
641 {
643 }
644 }
648 }
650 /* Similar to special_function_p; return a set of ERF_ flags for the
651 function FNDECL. */
652 static int
654 {
664 }
666 /* Return nonzero when FNDECL represents a call to setjmp. */
668 int
670 {
674 }
677 /* Return true if STMT may be an alloca call. */
679 bool
681 {
682 tree fndecl;
692 }
694 /* Return true if STMT is a builtin alloca call. */
696 bool
698 {
699 tree fndecl;
707 {
708 CASE_BUILT_IN_ALLOCA:
712 }
715 }
717 /* Return true when exp contains a builtin alloca call. */
719 bool
721 {
722 tree fndecl;
727 {
728 CASE_BUILT_IN_ALLOCA:
732 }
735 }
737 /* Return TRUE if FNDECL is either a TM builtin or a TM cloned
738 function. Return FALSE otherwise. */
740 static bool
742 {
750 {
752 {
795 }
796 }
798 }
800 /* Detect flags (function attributes) from the function decl or type node. */
802 int
804 {
808 {
809 /* The function exp may have the `malloc' attribute. */
813 /* The function exp may have the `returns_twice' attribute. */
817 /* Process the pure and const attributes. */
836 {
843 }
846 }
848 {
856 }
857 else
861 {
865 }
868 }
870 /* Detect flags from a CALL_EXPR. */
872 int
874 {
882 else
883 {
887 else
891 }
894 }
896 /* Return true if ARG should be passed by invisible reference. */
898 bool
900 {
902 {
903 /* If this type contains non-trivial constructors, then it is
904 forbidden for the middle-end to create any new copies. */
908 /* GCC post 3.4 passes *all* variable sized types by reference. */
912 /* If a record type should be passed the same as its first (and only)
913 member, use the type and mode of that member. */
915 {
918 }
919 }
922 }
924 /* Return true if TYPE should be passed by reference when passed to
925 the "..." arguments of a function. */
927 bool
929 {
931 }
933 /* Decide whether ARG, which occurs in the state described by CA,
934 should be passed by reference. Return true if so and update
935 ARG accordingly. */
937 bool
939 {
941 {
946 }
948 }
950 /* Return true if ARG, which is passed by reference, should be callee
951 copied instead of caller copied. */
953 bool
955 {
959 }
962 /* Precompute all register parameters as described by ARGS, storing values
963 into fields within the ARGS array.
965 NUM_ACTUALS indicates the total number elements in the ARGS array.
967 Set REG_PARM_SEEN if we encounter a register parameter. */
969 static void
972 {
979 {
983 {
988 }
990 /* If we are to promote the function arg to a wider mode,
991 do it now. */
999 /* If the value is a non-legitimate constant, force it into a
1000 pseudo now. TLS symbols sometimes need a call to resolve. */
1006 /* If we're going to have to load the value by parts, pull the
1007 parts into pseudos. The part extraction process can involve
1008 non-trivial computation. */
1010 {
1015 }
1017 /* If the value is expensive, and we are inside an appropriately
1018 short loop, put the value into a pseudo and then put the pseudo
1019 into the hard reg.
1021 For small register classes, also do this if this call uses
1022 register parameters. This is to avoid reload conflicts while
1023 loading the parameters registers. */
1032 && ((*reg_parm_seen
1036 }
1037 }
1039 #ifdef REG_PARM_STACK_SPACE
1041 /* The argument list is the property of the called routine and it
1042 may clobber it. If the fixed area has been used for previous
1043 parameters, we must save and restore it. */
1045 static rtx
1046 save_fixed_argument_area (int reg_parm_stack_space, rtx argblock, int *low_to_save, int *high_to_save)
1047 {
1051 /* Compute the boundary of the area that needs to be saved, if any. */
1061 {
1063 machine_mode save_mode;
1065 rtx addr;
1066 rtx stack_area;
1067 rtx save_area;
1070 ;
1077 /* If we don't have the required alignment, must do this
1078 in BLKmode. */
1079 scalar_int_mode imode;
1084 else
1089 else
1097 {
1101 }
1102 else
1103 {
1106 }
1109 }
1112 }
1114 static void
1116 {
1123 else
1132 else
1135 BLOCK_OP_CALL_PARM);
1136 }
1139 /* If any elements in ARGS refer to parameters that are to be passed in
1140 registers, but not in memory, and whose alignment does not permit a
1141 direct copy into registers. Copy the values into a group of pseudos
1142 which we will later copy into the appropriate hard registers.
1144 Pseudos for each unaligned argument will be stored into the array
1145 args[argnum].aligned_regs. The caller is responsible for deallocating
1146 the aligned_regs array if it is nonzero. */
1148 static void
1150 {
1160 {
1165 {
1168 }
1169 else
1170 {
1173 }
1177 /* Structures smaller than a word are normally aligned to the
1178 least significant byte. On a BYTES_BIG_ENDIAN machine,
1179 this means we must skip the empty high order bytes when
1180 calculating the bit offset. */
1182 #ifdef BLOCK_REG_PADDING
1186 #else
1187 && BYTES_BIG_ENDIAN
1188 #endif
1189 )
1193 {
1202 /* There is no need to restrict this code to loading items
1203 in TYPE_ALIGN sized hunks. The bitfield instructions can
1204 load up entire word sized registers efficiently.
1206 ??? This may not be needed anymore.
1207 We use to emit a clobber here but that doesn't let later
1208 passes optimize the instructions we emit. By storing 0 into
1209 the register later passes know the first AND to zero out the
1210 bitfield being set in the register is unnecessary. The store
1211 of 0 will be deleted as will at least the first AND. */
1218 }
1219 }
1220 }
1222 /* Issue an error if CALL_EXPR was flagged as requiring
1223 tall-call optimization. */
1225 void
1227 {
1233 }
1235 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
1236 CALL_EXPR EXP.
1238 NUM_ACTUALS is the total number of parameters.
1240 N_NAMED_ARGS is the total number of named arguments.
1242 STRUCT_VALUE_ADDR_VALUE is the implicit argument for a struct return
1243 value, or null.
1245 FNDECL is the tree code for the target of this call (if known)
1247 ARGS_SO_FAR holds state needed by the target to know where to place
1248 the next argument.
1250 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
1251 for arguments which are passed in registers.
1253 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
1254 and may be modified by this routine.
1256 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
1257 flags which may be modified by this routine.
1259 MAY_TAILCALL is cleared if we encounter an invisible pass-by-reference
1260 that requires allocation of stack space.
1262 CALL_FROM_THUNK_P is true if this call is the jump from a thunk to
1263 the thunked-to function. */
1265 static void
1272 cumulative_args_t args_so_far,
1278 {
1282 /* Count arg position in order args appear. */
1292 /* In this loop, we consider args in the order they are written.
1293 We fill up ARGS from the back. */
1296 {
1298 call_expr_arg_iterator iter;
1299 tree arg;
1303 {
1305 j--;
1306 }
1309 {
1313 && argtype
1316 {
1319 j--;
1321 }
1322 else
1324 j--;
1325 argpos++;
1326 }
1330 }
1334 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1336 {
1340 /* Replace erroneous argument with constant zero. */
1344 /* If TYPE is a transparent union or record, pass things the way
1345 we would pass the first field of the union or record. We have
1346 already verified that the modes are the same. */
1350 /* Decide where to pass this arg.
1352 args[i].reg is nonzero if all or part is passed in registers.
1354 args[i].partial is nonzero if part but not all is passed in registers,
1355 and the exact value says how many bytes are passed in registers.
1357 args[i].pass_on_stack is nonzero if the argument must at least be
1358 computed on the stack. It may then be loaded back into registers
1359 if args[i].reg is nonzero.
1361 These decisions are driven by the FUNCTION_... macros and must agree
1362 with those made by function.c. */
1364 /* See if this argument should be passed by invisible reference. */
1367 {
1368 const bool callee_copies
1370 tree base;
1372 /* If we're compiling a thunk, pass directly the address of an object
1373 already in memory, instead of making a copy. Likewise if we want
1374 to make the copy in the callee instead of the caller. */
1380 {
1381 /* We may have turned the parameter value into an SSA name.
1382 Go back to the original parameter so we can take the
1383 address. */
1385 {
1389 }
1390 /* Argument setup code may have copied the value to register. We
1391 revert that optimization now because the tail call code must
1392 use the original location. */
1402 /* We can't use sibcalls if a callee-copied argument is
1403 stored in the current function's frame. */
1405 {
1408 "a callee-copied argument is"
1409 " stored in the current"
1411 }
1419 }
1420 else
1421 {
1422 /* We make a copy of the object and pass the address to the
1423 function being called. */
1424 rtx copy;
1431 {
1432 /* This is a variable-sized object. Make space on the stack
1433 for it. */
1437 {
1441 }
1443 /* We can pass TRUE as the 4th argument because we just
1444 saved the stack pointer and will restore it right after
1445 the call. */
1449 max_int_size_in_bytes
1454 }
1455 else
1460 /* Just change the const function to pure and then let
1461 the next test clear the pure based on
1462 callee_copies. */
1464 {
1467 }
1477 "argument must be passed"
1479 }
1481 }
1485 arg.mode
1499 /* If this is a sibling call and the machine has register windows, the
1500 register window has to be unwinded before calling the routine, so
1501 arguments have to go into the incoming registers. */
1505 else
1513 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1514 it means that we are to pass this arg in the register(s) designated
1515 by the PARALLEL, but also to pass it in the stack. */
1520 /* If this is an addressable type, we must preallocate the stack
1521 since we must evaluate the object into its final location.
1523 If this is to be passed in both registers and the stack, it is simpler
1524 to preallocate. */
1529 /* Compute the stack-size of this argument. */
1534 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1536 #else
1538 #endif
1539 reg_parm_stack_space,
1542 #ifdef BLOCK_REG_PADDING
1543 else
1544 /* The argument is passed entirely in registers. See at which
1545 end it should be padded. */
1549 #endif
1551 /* Update ARGS_SIZE, the total stack space for args so far. */
1557 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1558 have been used, etc. */
1560 /* ??? Traditionally we've passed TYPE_MODE here, instead of the
1561 promoted_mode used for function_arg above. However, the
1562 corresponding handling of incoming arguments in function.c
1563 does pass the promoted mode. */
1566 }
1567 }
1569 /* Update ARGS_SIZE to contain the total size for the argument block.
1570 Return the original constant component of the argument block's size.
1572 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1573 for arguments passed in registers. */
1575 static poly_int64
1578 tree fndecl ATTRIBUTE_UNUSED,
1579 tree fntype ATTRIBUTE_UNUSED,
1581 {
1584 /* For accumulate outgoing args mode we don't need to align, since the frame
1585 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1586 backends from generating misaligned frame sizes. */
1590 /* Compute the actual size of the argument block required. The variable
1591 and constant sizes must be combined, the size may have to be rounded,
1592 and there may be a minimum required size. */
1595 {
1601 {
1602 /* We don't handle this case yet. To handle it correctly we have
1603 to add the delta, round and subtract the delta.
1604 Currently no machine description requires this support. */
1606 preferred_stack_boundary));
1608 }
1611 {
1612 args_size->var
1616 /* The area corresponding to register parameters is not to count in
1617 the size of the block we need. So make the adjustment. */
1619 args_size->var
1622 }
1623 }
1624 else
1625 {
1631 preferred_stack_boundary)
1635 reg_parm_stack_space);
1639 }
1641 }
1643 /* Precompute parameters as needed for a function call.
1645 FLAGS is mask of ECF_* constants.
1647 NUM_ACTUALS is the number of arguments.
1649 ARGS is an array containing information for each argument; this
1650 routine fills in the INITIAL_VALUE and VALUE fields for each
1651 precomputed argument. */
1653 static void
1655 {
1658 /* If this is a libcall, then precompute all arguments so that we do not
1659 get extraneous instructions emitted as part of the libcall sequence. */
1661 /* If we preallocated the stack space, and some arguments must be passed
1662 on the stack, then we must precompute any parameter which contains a
1663 function call which will store arguments on the stack.
1664 Otherwise, evaluating the parameter may clobber previous parameters
1665 which have already been stored into the stack. (we have code to avoid
1666 such case by saving the outgoing stack arguments, but it results in
1667 worse code) */
1672 {
1673 tree type;
1674 machine_mode mode;
1679 /* If this is an addressable type, we cannot pre-evaluate it. */
1688 {
1694 /* CSE will replace this only if it contains args[i].value
1695 pseudo, so convert it down to the declared mode using
1696 a SUBREG. */
1700 {
1705 }
1706 }
1707 }
1708 }
1710 /* Given the current state of MUST_PREALLOCATE and information about
1711 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1712 compute and return the final value for MUST_PREALLOCATE. */
1714 static int
1717 {
1718 /* See if we have or want to preallocate stack space.
1720 If we would have to push a partially-in-regs parm
1721 before other stack parms, preallocate stack space instead.
1723 If the size of some parm is not a multiple of the required stack
1724 alignment, we must preallocate.
1726 If the total size of arguments that would otherwise create a copy in
1727 a temporary (such as a CALL) is more than half the total argument list
1728 size, preallocation is faster.
1730 Another reason to preallocate is if we have a machine (like the m88k)
1731 where stack alignment is required to be maintained between every
1732 pair of insns, not just when the call is made. However, we assume here
1733 that such machines either do not have push insns (and hence preallocation
1734 would occur anyway) or the problem is taken care of with
1735 PUSH_ROUNDING. */
1738 {
1744 {
1755 copy_to_evaluate_size
1757 }
1762 }
1764 }
1766 /* If we preallocated stack space, compute the address of each argument
1767 and store it into the ARGS array.
1769 We need not ensure it is a valid memory address here; it will be
1770 validized when it is used.
1772 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1774 static void
1776 {
1778 {
1784 {
1787 }
1790 {
1793 rtx addr;
1798 /* Skip this parm if it will not be passed on the stack. */
1811 {
1812 /* Only part of the parameter is being passed on the stack.
1813 Generate a simple memory reference of the correct size. */
1819 }
1820 else
1821 {
1825 }
1828 poly_int64 offset_val;
1832 {
1834 unsigned int offset_align
1838 }
1845 {
1846 /* Only part of the parameter is being passed on the stack.
1847 Generate a simple memory reference of the correct size.
1848 */
1851 }
1852 else
1853 {
1857 }
1860 /* Function incoming arguments may overlap with sibling call
1861 outgoing arguments and we cannot allow reordering of reads
1862 from function arguments with stores to outgoing arguments
1863 of sibling calls. */
1866 }
1867 }
1868 }
1870 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1871 in a call instruction.
1873 FNDECL is the tree node for the target function. For an indirect call
1874 FNDECL will be NULL_TREE.
1876 ADDR is the operand 0 of CALL_EXPR for this call. */
1878 static rtx
1880 {
1881 rtx funexp;
1883 /* Get the function to call, in the form of RTL. */
1885 {
1889 /* Get a SYMBOL_REF rtx for the function address. */
1891 }
1892 else
1893 /* Generate an rtx (probably a pseudo-register) for the address. */
1894 {
1898 }
1900 }
1902 /* Return the static chain for this function, if any. */
1904 rtx
1906 {
1911 }
1913 /* Internal state for internal_arg_pointer_based_exp and its helpers. */
1914 static struct
1915 {
1916 /* Last insn that has been scanned by internal_arg_pointer_based_exp_scan,
1917 or NULL_RTX if none has been scanned yet. */
1919 /* Vector indexed by REGNO - FIRST_PSEUDO_REGISTER, recording if a pseudo is
1920 based on crtl->args.internal_arg_pointer. The element is NULL_RTX if the
1921 pseudo isn't based on it, a CONST_INT offset if the pseudo is based on it
1922 with fixed offset, or PC if this is with variable or unknown offset. */
1928 /* Helper function for internal_arg_pointer_based_exp. Scan insns in
1929 the tail call sequence, starting with first insn that hasn't been
1930 scanned yet, and note for each pseudo on the LHS whether it is based
1931 on crtl->args.internal_arg_pointer or not, and what offset from that
1932 that pointer it has. */
1934 static void
1936 {
1941 else
1945 {
1948 {
1951 /* Punt on pseudos set multiple times. */
1956 else
1959 {
1961 internal_arg_pointer_exp_state.cache
1964 }
1965 }
1969 }
1972 }
1974 /* Compute whether RTL is based on crtl->args.internal_arg_pointer. Return
1975 NULL_RTX if RTL isn't based on it, a CONST_INT offset if RTL is based on
1976 it with fixed offset, or PC if this is with variable or unknown offset.
1977 TOPLEVEL is true if the function is invoked at the topmost level. */
1979 static rtx
1981 {
1991 poly_int64 offset;
1993 {
1998 }
2000 /* When called at the topmost level, scan pseudo assignments in between the
2001 last scanned instruction in the tail call sequence and the latest insn
2002 in that sequence. */
2007 {
2013 }
2017 {
2023 }
2026 }
2028 /* Return true if SIZE bytes starting from address ADDR might overlap an
2029 already-clobbered argument area. This function is used to determine
2030 if we should give up a sibcall. */
2032 static bool
2034 {
2035 poly_int64 i;
2037 rtx val;
2053 else
2059 /* We can ignore any references to the function's pretend args,
2060 which at this point would manifest as negative values of I. */
2077 }
2079 /* Do the register loads required for any wholly-register parms or any
2080 parms which are passed both on the stack and in a register. Their
2081 expressions were already evaluated.
2083 Mark all register-parms as living through the call, putting these USE
2084 insns in the CALL_INSN_FUNCTION_USAGE field.
2086 When IS_SIBCALL, perform the check_sibcall_argument_overlap
2087 checking, setting *SIBCALL_FAILURE if appropriate. */
2089 static void
2093 {
2097 {
2101 {
2110 /* Set non-negative if we must move a word at a time, even if
2111 just one word (e.g, partial == 4 && mode == DFmode). Set
2112 to -1 if we just use a normal move insn. This value can be
2113 zero if the argument is a zero size structure. */
2116 ;
2118 {
2121 }
2123 {
2124 /* Variable-sized parameters should be described by a
2125 PARALLEL instead. */
2130 }
2131 else
2134 /* Handle calls that pass values in multiple non-contiguous
2135 locations. The Irix 6 ABI has examples of this. */
2140 /* If simple case, just do move. If normal partial, store_one_arg
2141 has already loaded the register for us. In all other cases,
2142 load the register(s) from memory. */
2145 {
2147 #ifdef BLOCK_REG_PADDING
2148 /* Handle case where we have a value that needs shifting
2149 up to the msb. eg. a QImode value and we're padding
2150 upward on a BYTES_BIG_ENDIAN machine. */
2153 {
2156 {
2157 rtx x;
2158 poly_int64 shift
2161 /* Assigning REG here rather than a temp makes
2162 CALL_FUSAGE report the whole reg as used.
2163 Strictly speaking, the call only uses SIZE
2164 bytes at the msb end, but it doesn't seem worth
2165 generating rtl to say that. */
2171 }
2172 }
2173 #endif
2174 }
2176 /* If we have pre-computed the values to put in the registers in
2177 the case of non-aligned structures, copy them in now. */
2185 {
2186 /* SIZE and CONST_SIZE are 0 for partial arguments and
2187 the size of a BLKmode type otherwise. */
2191 /* Check for overlap with already clobbered argument area,
2192 providing that this has non-zero size. */
2195 && (mem_might_overlap_already_clobbered_arg_p
2202 else
2203 {
2212 NULL);
2218 }
2220 /* Handle a BLKmode that needs shifting. */
2222 #ifdef BLOCK_REG_PADDING
2224 #else
2225 && BYTES_BIG_ENDIAN
2226 #endif
2227 )
2228 {
2233 rtx x;
2238 }
2239 }
2241 /* When a parameter is a block, and perhaps in other cases, it is
2242 possible that it did a load from an argument slot that was
2243 already clobbered. */
2248 /* Handle calls that pass values in multiple non-contiguous
2249 locations. The Irix 6 ABI has examples of this. */
2256 }
2257 }
2258 }
2260 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
2261 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
2262 bytes, then we would need to push some additional bytes to pad the
2263 arguments. So, we try to compute an adjust to the stack pointer for an
2264 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
2265 bytes. Then, when the arguments are pushed the stack will be perfectly
2266 aligned.
2268 Return true if this optimization is possible, storing the adjustment
2269 in ADJUSTMENT_OUT and setting ARGS_SIZE->CONSTANT to the number of
2270 bytes that should be popped after the call. */
2272 static bool
2274 poly_int64 unadjusted_args_size,
2277 {
2278 /* The number of bytes to pop so that the stack will be
2279 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
2280 poly_int64 adjustment;
2281 /* The alignment of the stack after the arguments are pushed, if we
2282 just pushed the arguments without adjust the stack here. */
2286 preferred_unit_stack_boundary,
2290 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
2291 as possible -- leaving just enough left to cancel out the
2292 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
2293 PENDING_STACK_ADJUST is non-negative, and congruent to
2294 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
2296 /* Begin by trying to pop all the bytes. */
2299 preferred_unit_stack_boundary,
2304 /* Push enough additional bytes that the stack will be aligned
2305 after the arguments are pushed. */
2309 /* We need to know whether the adjusted argument size
2310 (UNADJUSTED_ARGS_SIZE - ADJUSTMENT) constitutes an allocation
2311 or a deallocation. */
2315 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
2316 bytes after the call. The right number is the entire
2317 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
2318 by the arguments in the first place. */
2319 args_size->constant
2324 }
2326 /* Scan X expression if it does not dereference any argument slots
2327 we already clobbered by tail call arguments (as noted in stored_args_map
2328 bitmap).
2329 Return nonzero if X expression dereferences such argument slots,
2330 zero otherwise. */
2332 static int
2334 {
2335 RTX_CODE code;
2344 /* We need not check the operands of the CALL expression itself. */
2352 /* Scan all subexpressions. */
2355 {
2357 {
2360 }
2362 {
2366 }
2367 }
2369 }
2371 /* Scan sequence after INSN if it does not dereference any argument slots
2372 we already clobbered by tail call arguments (as noted in stored_args_map
2373 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
2374 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
2375 should be 0). Return nonzero if sequence after INSN dereferences such argument
2376 slots, zero otherwise. */
2378 static int
2381 {
2387 else
2396 {
2399 else
2407 else
2409 }
2411 }
2413 /* Given that a function returns a value of mode MODE at the most
2414 significant end of hard register VALUE, shift VALUE left or right
2415 as specified by LEFT_P. Return true if some action was needed. */
2417 bool
2419 {
2427 /* Use ashr rather than lshr for right shifts. This is for the benefit
2428 of the MIPS port, which requires SImode values to be sign-extended
2429 when stored in 64-bit registers. */
2435 }
2437 /* If X is a likely-spilled register value, copy it to a pseudo
2438 register and return that register. Return X otherwise. */
2440 static rtx
2442 {
2443 rtx new_rtx;
2448 {
2449 /* Make sure that we generate a REG rather than a CONCAT.
2450 Moves into CONCATs can need nontrivial instructions,
2451 and the whole point of this function is to avoid
2452 using the hard register directly in such a situation. */
2458 }
2460 }
2462 /* Helper function for expand_call.
2463 Return false is EXP is not implementable as a sibling call. */
2465 static bool
2467 rtx structure_value_addr,
2468 tree funtype,
2469 tree fndecl,
2471 tree addr,
2473 {
2475 {
2476 maybe_complain_about_tail_call
2478 "machine description does not have"
2481 }
2483 /* Doing sibling call optimization needs some work, since
2484 structure_value_addr can be allocated on the stack.
2485 It does not seem worth the effort since few optimizable
2486 sibling calls will return a structure. */
2488 {
2491 }
2493 /* Check whether the target is able to optimize the call
2494 into a sibcall. */
2496 {
2498 "target is not able to optimize the"
2501 }
2503 /* Functions that do not return exactly once may not be sibcall
2504 optimized. */
2506 {
2509 }
2511 {
2514 }
2517 {
2520 }
2522 /* If the called function is nested in the current one, it might access
2523 some of the caller's arguments, but could clobber them beforehand if
2524 the argument areas are shared. */
2526 {
2529 }
2531 /* If this function requires more stack slots than the current
2532 function, we cannot change it into a sibling call.
2533 crtl->args.pretend_args_size is not part of the
2534 stack allocated by our caller. */
2537 {
2539 "callee required more stack slots"
2542 }
2544 /* If the callee pops its own arguments, then it must pop exactly
2545 the same number of arguments as the current function. */
2549 TREE_TYPE
2552 {
2554 "inconsistent number of"
2557 }
2560 {
2564 }
2566 /* All checks passed. */
2568 }
2570 /* Update stack alignment when the parameter is passed in the stack
2571 since the outgoing parameter requires extra alignment on the calling
2572 function side. */
2574 static void
2576 {
2581 }
2583 /* Generate all the code for a CALL_EXPR exp
2584 and return an rtx for its value.
2585 Store the value in TARGET (specified as an rtx) if convenient.
2586 If the value is stored in TARGET then TARGET is returned.
2587 If IGNORE is nonzero, then we ignore the value of the function call. */
2589 rtx
2591 {
2592 /* Nonzero if we are currently expanding a call. */
2595 /* RTX for the function to be called. */
2596 rtx funexp;
2597 /* Sequence of insns to perform a normal "call". */
2599 /* Sequence of insns to perform a tail "call". */
2601 /* Data type of the function. */
2602 tree funtype;
2603 tree type_arg_types;
2604 tree rettype;
2605 /* Declaration of the function being called,
2606 or 0 if the function is computed (not known by name). */
2608 /* The type of the function being called. */
2609 tree fntype;
2614 /* Register in which non-BLKmode value will be returned,
2615 or 0 if no value or if value is BLKmode. */
2616 rtx valreg;
2617 /* Address where we should return a BLKmode value;
2618 0 if value not BLKmode. */
2620 /* Nonzero if that address is being passed by treating it as
2621 an extra, implicit first parameter. Otherwise,
2622 it is passed by being copied directly into struct_value_rtx. */
2624 /* Holds the value of implicit argument for the struct value. */
2626 /* Size of aggregate value wanted, or zero if none wanted
2627 or if we are using the non-reentrant PCC calling convention
2628 or expecting the value in registers. */
2630 /* Nonzero if called function returns an aggregate in memory PCC style,
2631 by returning the address of where to find it. */
2635 /* Number of actual parameters in this call, including struct value addr. */
2637 /* Number of named args. Args after this are anonymous ones
2638 and they must all go on the stack. */
2640 /* Number of complex actual arguments that need to be split. */
2643 /* Vector of information about each argument.
2644 Arguments are numbered in the order they will be pushed,
2645 not the order they are written. */
2648 /* Total size in bytes of all the stack-parms scanned so far. */
2651 /* Size of arguments before any adjustments (such as rounding). */
2652 poly_int64 unadjusted_args_size;
2653 /* Data on reg parms scanned so far. */
2654 CUMULATIVE_ARGS args_so_far_v;
2655 cumulative_args_t args_so_far;
2656 /* Nonzero if a reg parm has been scanned. */
2658 /* Nonzero if this is an indirect function call. */
2660 /* Nonzero if we must avoid push-insns in the args for this call.
2661 If stack space is allocated for register parameters, but not by the
2662 caller, then it is preallocated in the fixed part of the stack frame.
2663 So the entire argument block must then be preallocated (i.e., we
2664 ignore PUSH_ROUNDING in that case). */
2668 /* Size of the stack reserved for parameter registers. */
2671 /* Address of space preallocated for stack parms
2672 (on machines that lack push insns), or 0 if space not preallocated. */
2675 /* Mask of ECF_ and ERF_ flags. */
2678 #ifdef REG_PARM_STACK_SPACE
2679 /* Define the boundary of the register parm stack space that needs to be
2680 saved, if any. */
2683 #endif
2690 poly_int64 old_stack_allocated;
2692 /* State variables to track stack modifications. */
2698 /* Some stack pointer alterations we make are performed via
2699 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2700 which we then also need to save/restore along the way. */
2703 rtx call_fusage;
2706 /* The alignment of the stack, in bits. */
2708 /* The alignment of the stack, in bytes. */
2710 /* The static chain value to use for this call. */
2711 rtx static_chain_value;
2712 /* See if this is "nothrow" function call. */
2716 /* See if we can find a DECL-node for the actual function, and get the
2717 function attributes (flags) from the function decl or type node. */
2720 {
2724 }
2725 else
2726 {
2731 }
2736 /* Warn if this value is an aggregate type,
2737 regardless of which calling convention we are using for it. */
2741 /* If the result of a non looping pure or const function call is
2742 ignored (or void), and none of its arguments are volatile, we can
2743 avoid expanding the call and just evaluate the arguments for
2744 side-effects. */
2750 {
2752 tree arg;
2753 call_expr_arg_iterator iter;
2757 {
2760 }
2763 {
2767 }
2768 }
2770 #ifdef REG_PARM_STACK_SPACE
2772 #endif
2778 /* Set up a place to return a structure. */
2780 /* Cater to broken compilers. */
2782 {
2783 /* This call returns a big structure. */
2786 #ifdef PCC_STATIC_STRUCT_RETURN
2787 {
2789 }
2791 {
2795 /* Even if it is semantically safe to use the target as the return
2796 slot, it may be not sufficiently aligned for the return type. */
2798 && target
2800 /* If rettype is addressable, we may not create a temporary.
2801 If target is properly aligned at runtime and the compiler
2802 just doesn't know about it, it will work fine, otherwise it
2803 will be UB. */
2809 else
2810 {
2811 /* For variable-sized objects, we must be called with a target
2812 specified. If we were to allocate space on the stack here,
2813 we would have no way of knowing when to free it. */
2817 }
2818 }
2820 }
2822 /* Figure out the amount to which the stack should be aligned. */
2825 {
2827 /* Without automatic stack alignment, we can't increase preferred
2828 stack boundary. With automatic stack alignment, it is
2829 unnecessary since unless we can guarantee that all callers will
2830 align the outgoing stack properly, callee has to align its
2831 stack anyway. */
2836 }
2838 /* Operand 0 is a pointer-to-function; get the type of the function. */
2843 /* Count whether there are actual complex arguments that need to be split
2844 into their real and imaginary parts. Munge the type_arg_types
2845 appropriately here as well. */
2847 {
2848 call_expr_arg_iterator iter;
2849 tree arg;
2851 {
2855 num_complex_actuals++;
2856 }
2858 }
2859 else
2865 /* If struct_value_rtx is 0, it means pass the address
2866 as if it were an extra parameter. Put the argument expression
2867 in structure_value_addr_value. */
2869 {
2870 /* If structure_value_addr is a REG other than
2871 virtual_outgoing_args_rtx, we can use always use it. If it
2872 is not a REG, we must always copy it into a register.
2873 If it is virtual_outgoing_args_rtx, we must copy it to another
2874 register in some cases. */
2876 || (ACCUMULATE_OUTGOING_ARGS
2877 && stack_arg_under_construction
2883 structure_value_addr_value =
2886 }
2888 /* Count the arguments and set NUM_ACTUALS. */
2889 num_actuals =
2892 /* Compute number of named args.
2893 First, do a raw count of the args for INIT_CUMULATIVE_ARGS. */
2896 n_named_args
2898 /* Count the struct value address, if it is passed as a parm. */
2900 else
2901 /* If we know nothing, treat all args as named. */
2904 /* Start updating where the next arg would go.
2906 On some machines (such as the PA) indirect calls have a different
2907 calling convention than normal calls. The fourth argument in
2908 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2909 or not. */
2913 /* Now possibly adjust the number of named args.
2914 Normally, don't include the last named arg if anonymous args follow.
2915 We do include the last named arg if
2916 targetm.calls.strict_argument_naming() returns nonzero.
2917 (If no anonymous args follow, the result of list_length is actually
2918 one too large. This is harmless.)
2920 If targetm.calls.pretend_outgoing_varargs_named() returns
2921 nonzero, and targetm.calls.strict_argument_naming() returns zero,
2922 this machine will be able to place unnamed args that were passed
2923 in registers into the stack. So treat all args as named. This
2924 allows the insns emitting for a specific argument list to be
2925 independent of the function declaration.
2927 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
2928 we do not have any reliable way to pass unnamed args in
2929 registers, so we must force them into memory. */
2933 ;
2936 /* Don't include the last named arg. */
2938 else
2939 /* Treat all args as named. */
2942 /* Make a vector to hold all the information about each arg. */
2945 /* Build up entries in the ARGS array, compute the size of the
2946 arguments into ARGS_SIZE, etc. */
2958 /* Now make final decision about preallocating stack space. */
2963 /* If the structure value address will reference the stack pointer, we
2964 must stabilize it. We don't need to do this if we know that we are
2965 not going to adjust the stack pointer in processing this call. */
2970 structure_value_addr))
2972 || (!ACCUMULATE_OUTGOING_ARGS
2976 /* Tail calls can make things harder to debug, and we've traditionally
2977 pushed these optimizations into -O2. Don't try if we're already
2978 expanding a call, as that means we're an argument. Don't try if
2979 there's cleanups, as we know there's code to follow the call. */
2986 /* Workaround buggy C/C++ wrappers around Fortran routines with
2987 character(len=constant) arguments if the hidden string length arguments
2988 are passed on the stack; if the callers forget to pass those arguments,
2989 attempting to tail call in such routines leads to stack corruption.
2990 Avoid tail calls in functions where at least one such hidden string
2991 length argument is passed (partially or fully) on the stack in the
2992 caller and the callee needs to pass any arguments on the stack.
2993 See PR90329. */
2998 {
3002 {
3005 }
3006 }
3008 /* If the user has marked the function as requiring tail-call
3009 optimization, attempt it. */
3013 /* Rest of purposes for tail call optimizations to fail. */
3016 structure_value_addr,
3017 funtype,
3018 fndecl,
3021 /* Check if caller and callee disagree in promotion of function
3022 return value. */
3024 {
3034 caller_promoted_mode
3038 callee_promoted_mode
3048 {
3051 "caller and callee disagree in"
3052 " promotion of function"
3054 }
3055 }
3057 /* Ensure current function's preferred stack boundary is at least
3058 what we need. Stack alignment may also increase preferred stack
3059 boundary. */
3068 else
3076 /* We want to make two insn chains; one for a sibling call, the other
3077 for a normal call. We will select one of the two chains after
3078 initial RTL generation is complete. */
3080 {
3082 /* We want to emit any pending stack adjustments before the tail
3083 recursion "call". That way we know any adjustment after the tail
3084 recursion call can be ignored if we indeed use the tail
3085 call expansion. */
3086 saved_pending_stack_adjust save;
3088 rtx next_arg_reg;
3091 {
3092 /* State variables we need to save and restore between
3093 iterations. */
3095 }
3098 else
3101 /* Other state variables that we must reinitialize each time
3102 through the loop (that are not initialized by the loop itself). */
3106 /* Start a new sequence for the normal call case.
3108 From this point on, if the sibling call fails, we want to set
3109 sibcall_failure instead of continuing the loop. */
3112 /* Don't let pending stack adjusts add up to too much.
3113 Also, do all pending adjustments now if there is any chance
3114 this might be a call to alloca or if we are expanding a sibling
3115 call sequence.
3116 Also do the adjustments before a throwing call, otherwise
3117 exception handling can fail; PR 19225. */
3126 /* Precompute any arguments as needed. */
3130 /* Now we are about to start emitting insns that can be deleted
3131 if a libcall is deleted. */
3141 /* Compute the actual size of the argument block required. The variable
3142 and constant sizes must be combined, the size may have to be rounded,
3143 and there may be a minimum required size. When generating a sibcall
3144 pattern, do not round up, since we'll be re-using whatever space our
3145 caller provided. */
3146 unadjusted_args_size
3155 /* The argument block when performing a sibling call is the
3156 incoming argument block. */
3158 {
3161 argblock
3163 else
3164 argblock
3171 }
3173 /* If we have no actual push instructions, or shouldn't use them,
3174 make space for all args right now. */
3176 {
3178 {
3183 /* stack_arg_under_construction says whether a stack arg is
3184 being constructed at the old stack level. Pushing the stack
3185 gets a clean outgoing argument block. */
3188 }
3192 }
3193 else
3194 {
3195 /* Note that we must go through the motions of allocating an argument
3196 block even if the size is zero because we may be storing args
3197 in the area reserved for register arguments, which may be part of
3198 the stack frame. */
3202 /* Store the maximum argument space used. It will be pushed by
3203 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
3204 checking). */
3207 needed);
3210 {
3212 {
3213 /* Since the stack pointer will never be pushed, it is
3214 possible for the evaluation of a parm to clobber
3215 something we have already written to the stack.
3216 Since most function calls on RISC machines do not use
3217 the stack, this is uncommon, but must work correctly.
3219 Therefore, we save any area of the stack that was already
3220 written and that we are using. Here we set up to do this
3221 by making a new stack usage map from the old one. The
3222 actual save will be done by store_one_arg.
3224 Another approach might be to try to reorder the argument
3225 evaluations to avoid this conflicting stack usage. */
3227 /* Since we will be writing into the entire argument area,
3228 the map must be allocated for its entire size, not just
3229 the part that is the responsibility of the caller. */
3237 /* For polynomial sizes, this is the maximum possible
3238 size needed for arguments with a constant size
3239 and offset. */
3241 highest_outgoing_arg_in_use
3250 initial_highest_arg_in_use);
3254 (highest_outgoing_arg_in_use
3258 /* The address of the outgoing argument list must not be
3259 copied to a register here, because argblock would be left
3260 pointing to the wrong place after the call to
3261 allocate_dynamic_stack_space below. */
3264 }
3265 else
3266 {
3267 /* Try to reuse some or all of the pending_stack_adjust
3268 to get this space. */
3270 && (combine_pending_stack_adjustment_and_call
3272 unadjusted_args_size,
3274 preferred_unit_stack_boundary)))
3275 {
3276 /* combine_pending_stack_adjustment_and_call computes
3277 an adjustment before the arguments are allocated.
3278 Account for them and see whether or not the stack
3279 needs to go up or down. */
3282 /* Checked by
3283 combine_pending_stack_adjustment_and_call. */
3286 {
3287 /* We're releasing stack space. */
3288 /* ??? We can avoid any adjustment at all if we're
3289 already aligned. FIXME. */
3293 }
3294 else
3295 /* We need to allocate space. We'll do that in
3296 push_block below. */
3298 }
3300 /* Special case this because overhead of `push_block' in
3301 this case is non-trivial. */
3304 else
3305 {
3310 }
3312 /* We only really need to call `copy_to_reg' in the case
3313 where push insns are going to be used to pass ARGBLOCK
3314 to a function call in ARGS. In that case, the stack
3315 pointer changes value from the allocation point to the
3316 call point, and hence the value of
3317 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
3318 as well always do it. */
3320 }
3321 }
3322 }
3325 {
3326 /* The save/restore code in store_one_arg handles all
3327 cases except one: a constructor call (including a C
3328 function returning a BLKmode struct) to initialize
3329 an argument. */
3331 {
3332 rtx push_size
3333 = (gen_int_mode
3339 {
3344 /* stack_arg_under_construction says whether a stack
3345 arg is being constructed at the old stack level.
3346 Pushing the stack gets a clean outgoing argument
3347 block. */
3348 old_stack_arg_under_construction
3351 /* Make a new map for the new argument list. */
3357 }
3358 /* We can pass TRUE as the 4th argument because we just
3359 saved the stack pointer and will restore it right after
3360 the call. */
3363 }
3365 /* If argument evaluation might modify the stack pointer,
3366 copy the address of the argument list to a register. */
3369 {
3372 }
3373 }
3377 /* Stack is properly aligned, pops can't safely be deferred during
3378 the evaluation of the arguments. */
3379 NO_DEFER_POP;
3381 /* Precompute all register parameters. It isn't safe to compute
3382 anything once we have started filling any specific hard regs.
3383 TLS symbols sometimes need a call to resolve. Precompute
3384 register parameters before any stack pointer manipulation
3385 to avoid unaligned stack in the called function. */
3388 OK_DEFER_POP;
3390 /* Perform stack alignment before the first push (the last arg). */
3394 {
3395 /* When the stack adjustment is pending, we get better code
3396 by combining the adjustments. */
3398 && ! inhibit_defer_pop
3399 && (combine_pending_stack_adjustment_and_call
3401 unadjusted_args_size,
3403 preferred_unit_stack_boundary)))
3408 Pmode));
3409 }
3410 /* Now that the stack is properly aligned, pops can't safely
3411 be deferred during the evaluation of the arguments. */
3412 NO_DEFER_POP;
3414 /* Record the maximum pushed stack space size. We need to delay
3415 doing it this far to take into account the optimization done
3416 by combine_pending_stack_adjustment_and_call. */
3418 && !ACCUMULATE_OUTGOING_ARGS
3419 && pass
3421 {
3424 current_function_pushed_stack_size
3426 }
3432 else
3435 #ifdef REG_PARM_STACK_SPACE
3436 /* Save the fixed argument area if it's part of the caller's frame and
3437 is clobbered by argument setup for this call. */
3441 #endif
3443 /* Now store (and compute if necessary) all non-register parms.
3444 These come before register parms, since they can require block-moves,
3445 which could clobber the registers used for register parms.
3446 Parms which have partial registers are not stored here,
3447 but we do preallocate space here if they want that. */
3450 {
3452 {
3455 /* We don't allow passing huge (> 2^30 B) arguments
3456 by value. It would cause an overflow later on. */
3459 {
3462 }
3466 reg_parm_stack_space)
3471 }
3474 call_fusage
3477 call_fusage);
3478 }
3480 /* If we have a parm that is passed in registers but not in memory
3481 and whose alignment does not permit a direct copy into registers,
3482 make a group of pseudos that correspond to each register that we
3483 will later fill. */
3487 /* Now store any partially-in-registers parm.
3488 This is the last place a block-move can happen. */
3492 {
3495 /* On targets with weird calling conventions (e.g. PA) it's
3496 hard to ensure that all cases of argument overlap between
3497 stack and registers work. Play it safe and bail out. */
3499 {
3502 }
3506 reg_parm_stack_space)
3511 }
3516 {
3519 }
3523 /* Figure out the register where the value, if any, will come back. */
3527 {
3531 else
3535 /* If VALREG is a PARALLEL whose first member has a zero
3536 offset, use that. This is for targets such as m68k that
3537 return the same value in multiple places. */
3539 {
3546 }
3547 }
3549 /* If register arguments require space on the stack and stack space
3550 was not preallocated, allocate stack space here for arguments
3551 passed in registers. */
3553 && !ACCUMULATE_OUTGOING_ARGS
3557 /* Pass the function the address in which to return a
3558 structure value. */
3560 {
3561 structure_value_addr
3566 NULL_RTX)));
3570 }
3580 /* Save a pointer to the last insn before the call, so that we can
3581 later safely search backwards to find the CALL_INSN. */
3584 /* Set up next argument register. For sibling calls on machines
3585 with register windows this should be the incoming register. */
3589 else
3594 {
3600 && valreg
3603 call_fusage
3606 call_fusage);
3607 }
3608 /* All arguments and registers used for the call must be set up by
3609 now! */
3611 /* Stack must be properly aligned now. */
3614 preferred_unit_stack_boundary));
3616 /* Generate the actual call instruction. */
3623 {
3627 {
3631 }
3634 }
3636 /* If the call setup or the call itself overlaps with anything
3637 of the argument setup we probably clobbered our call address.
3638 In that case we can't do sibcalls. */
3643 /* If a non-BLKmode value is returned at the most significant end
3644 of a register, shift the register right by the appropriate amount
3645 and update VALREG accordingly. BLKmode values are handled by the
3646 group load/store machinery below. */
3648 && !pcc_struct_value
3653 {
3657 }
3660 {
3664 /* The return value from a malloc-like function is a pointer. */
3670 /* The return value from a malloc-like function cannot alias
3671 anything else. */
3675 /* Write out the sequence. */
3680 }
3682 /* For calls to `setjmp', etc., inform
3683 function.c:setjmp_warnings that it should complain if
3684 nonvolatile values are live. For functions that cannot
3685 return, inform flow that control does not fall through. */
3688 {
3689 /* The barrier must be emitted
3690 immediately after the CALL_INSN. Some ports emit more
3691 than just a CALL_INSN above, so we must search for it here. */
3695 {
3697 /* There was no CALL_INSN? */
3699 }
3703 /* Stack adjustments after a noreturn call are dead code.
3704 However when NO_DEFER_POP is in effect, we must preserve
3705 stack_pointer_delta. */
3707 {
3710 }
3711 }
3713 /* If value type not void, return an rtx for the value. */
3719 {
3721 {
3722 target
3725 structure_value_addr));
3727 }
3728 }
3730 {
3731 /* This is the special C++ case where we need to
3732 know what the true target was. We take care to
3733 never use this value more than once in one expression. */
3737 }
3738 /* Handle calls that return values in multiple non-contiguous locations.
3739 The Irix 6 ABI has examples of this. */
3741 {
3745 ;
3747 /* Handle the result of a emit_group_move_into_temps
3748 call in the previous pass. */
3750 else
3753 }
3757 {
3760 /* We have to copy a return value in a CLASS_LIKELY_SPILLED hard
3761 reg to a plain register. */
3765 /* If TARGET is a MEM in the argument area, and we have
3766 saved part of the argument area, then we can't store
3767 directly into TARGET as it may get overwritten when we
3768 restore the argument save area below. Don't work too
3769 hard though and simply force TARGET to a register if it
3770 is a MEM; the optimizer is quite likely to sort it out. */
3774 {
3777 }
3781 else
3782 {
3783 /* TARGET and VALREG cannot be equal at this point
3784 because the latter would not have
3785 REG_FUNCTION_VALUE_P true, while the former would if
3786 it were referring to the same register.
3788 If they refer to the same register, this move will be
3789 a no-op, except when function inlining is being
3790 done. */
3793 /* If we are setting a MEM, this code must be executed.
3794 Since it is emitted after the call insn, sibcall
3795 optimization cannot be performed in that case. */
3798 }
3799 }
3800 else
3803 /* If we promoted this return value, make the proper SUBREG.
3804 TARGET might be const0_rtx here, so be careful. */
3808 {
3811 machine_mode pmode;
3813 /* Ensure we promote as expected, and get the new unsignedness. */
3823 }
3825 /* If size of args is variable or this was a constructor call for a stack
3826 argument, restore saved stack-pointer value. */
3829 {
3844 }
3846 {
3847 #ifdef REG_PARM_STACK_SPACE
3851 #endif
3853 /* If we saved any argument areas, restore them. */
3856 {
3858 rtx stack_area
3865 else
3867 (gen_int_mode
3869 BLOCK_OP_CALL_PARM);
3870 }
3875 }
3877 /* If this was alloca, record the new stack level. */
3881 /* Free up storage we no longer need. */
3891 {
3894 /* Restore the pending stack adjustment now that we have
3895 finished generating the sibling call sequence. */
3899 /* Prepare arg structure for next iteration. */
3901 {
3905 }
3910 }
3911 else
3912 {
3915 /* Verify that we've deallocated all the stack we used. */
3918 stack_pointer_delta
3920 }
3922 /* If something prevents making this a sibling call,
3923 zero out the sequence. */
3926 else
3928 }
3930 /* If tail call production succeeded, we need to remove REG_EQUIV notes on
3931 arguments too, as argument area is now clobbered by the call. */
3933 {
3936 }
3937 else
3938 {
3941 /* Ideally we'd emit a message for all of the ways that it could
3942 have failed. */
3944 }
3946 currently_expanding_call--;
3951 }
3953 /* A sibling call sequence invalidates any REG_EQUIV notes made for
3954 this function's incoming arguments.
3956 At the start of RTL generation we know the only REG_EQUIV notes
3957 in the rtl chain are those for incoming arguments, so we can look
3958 for REG_EQUIV notes between the start of the function and the
3959 NOTE_INSN_FUNCTION_BEG.
3961 This is (slight) overkill. We could keep track of the highest
3962 argument we clobber and be more selective in removing notes, but it
3963 does not seem to be worth the effort. */
3965 void
3967 {
3971 {
3972 rtx note;
3974 /* There are never REG_EQUIV notes for the incoming arguments
3975 after the NOTE_INSN_FUNCTION_BEG note, so stop if we see it. */
3985 }
3986 }
3988 /* Traverse a list of TYPES and expand all complex types into their
3989 components. */
3990 static tree
3992 {
3993 tree p;
3995 /* Before allocating memory, check for the common case of no complex. */
3997 {
4002 }
4005 found:
4009 {
4014 {
4017 /* Rewrite complex type with component type. */
4021 /* Add another component type for the imaginary part. */
4026 /* Skip the newly created node. */
4028 }
4029 }
4032 }
4033 \f
4034 /* Output a library call to function ORGFUN (a SYMBOL_REF rtx)
4035 for a value of mode OUTMODE,
4036 with NARGS different arguments, passed as ARGS.
4037 Store the return value if RETVAL is nonzero: store it in VALUE if
4038 VALUE is nonnull, otherwise pick a convenient location. In either
4039 case return the location of the stored value.
4041 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for
4042 `const' calls, LCT_PURE for `pure' calls, or another LCT_ value for
4043 other types of library calls. */
4045 rtx
4049 {
4050 /* Total size in bytes of all the stack-parms scanned so far. */
4052 /* Size of arguments before any adjustments (such as rounding). */
4055 rtx fun;
4056 /* Todo, choose the correct decl type of orgfun. Sadly this information
4057 isn't present here, so we default to native calling abi here. */
4062 CUMULATIVE_ARGS args_so_far_v;
4063 cumulative_args_t args_so_far;
4064 struct arg
4065 {
4066 rtx value;
4067 machine_mode mode;
4068 rtx reg;
4071 rtx save_area;
4072 };
4077 rtx valreg;
4082 poly_int64 needed;
4087 #ifdef REG_PARM_STACK_SPACE
4088 /* Define the boundary of the register parm stack space that needs to be
4089 save, if any. */
4092 #endif
4094 /* Size of the stack reserved for parameter registers. */
4102 #ifdef REG_PARM_STACK_SPACE
4104 #endif
4106 /* By default, library functions cannot throw. */
4110 {
4128 }
4131 /* Ensure current function's preferred stack boundary is at least
4132 what we need. */
4136 /* If this kind of value comes back in memory,
4137 decide where in memory it should come back. */
4139 {
4142 {
4143 #ifdef PCC_STATIC_STRUCT_RETURN
4144 rtx pointer_reg
4154 else
4156 #endif
4157 /* This call returns a big structure. */
4159 }
4160 }
4161 else
4164 /* ??? Unfinished: must pass the memory address as an argument. */
4166 /* Copy all the libcall-arguments out of the varargs data
4167 and into a vector ARGVEC.
4169 Compute how to pass each argument. We only support a very small subset
4170 of the full argument passing conventions to limit complexity here since
4171 library functions shouldn't have many args. */
4176 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
4178 #else
4180 #endif
4190 /* If there's a structure value address to be passed,
4191 either pass it in the special place, or pass it as an extra argument. */
4193 {
4196 nargs++;
4198 /* Make sure it is a reasonable operand for a move or push insn. */
4213 #ifdef STACK_PARMS_IN_REG_PARM_AREA
4215 #else
4217 #endif
4227 count++;
4228 }
4231 {
4236 /* We cannot convert the arg value to the mode the library wants here;
4237 must do it earlier where we know the signedness of the arg. */
4242 /* Make sure it is a reasonable operand for a move or push insn. */
4249 {
4250 rtx slot;
4253 /* If this was a CONST function, it is now PURE since it now
4254 reads memory. */
4256 {
4259 }
4262 {
4267 }
4268 else
4269 {
4273 }
4277 call_fusage);
4281 slot),
4282 call_fusage);
4287 }
4293 unsigned_p);
4302 {
4304 #ifdef STACK_PARMS_IN_REG_PARM_AREA
4306 #else
4308 #endif
4313 }
4314 #ifdef BLOCK_REG_PADDING
4315 else
4316 /* The argument is passed entirely in registers. See at which
4317 end it should be padded. */
4321 UNITS_PER_WORD));
4322 #endif
4325 }
4333 /* If this machine requires an external definition for library
4334 functions, write one out. */
4340 STACK_BYTES)
4344 reg_parm_stack_space);
4353 {
4355 current_function_pushed_stack_size
4357 }
4360 {
4361 /* Since the stack pointer will never be pushed, it is possible for
4362 the evaluation of a parm to clobber something we have already
4363 written to the stack. Since most function calls on RISC machines
4364 do not use the stack, this is uncommon, but must work correctly.
4366 Therefore, we save any area of the stack that was already written
4367 and that we are using. Here we set up to do this by making a new
4368 stack usage map from the old one.
4370 Another approach might be to try to reorder the argument
4371 evaluations to avoid this conflicting stack usage. */
4375 /* Since we will be writing into the entire argument area, the
4376 map must be allocated for its entire size, not just the part that
4377 is the responsibility of the caller. */
4385 /* For polynomial sizes, this is the maximum possible size needed
4386 for arguments with a constant size and offset. */
4389 const_limit);
4396 initial_highest_arg_in_use);
4403 /* We must be careful to use virtual regs before they're instantiated,
4404 and real regs afterwards. Loop optimization, for example, can create
4405 new libcalls after we've instantiated the virtual regs, and if we
4406 use virtuals anyway, they won't match the rtl patterns. */
4410 STACK_POINTER_OFFSET);
4411 else
4413 }
4414 else
4415 {
4418 }
4420 /* We push args individually in reverse order, perform stack alignment
4421 before the first push (the last arg). */
4425 Pmode));
4429 #ifdef REG_PARM_STACK_SPACE
4431 {
4432 /* The argument list is the property of the called routine and it
4433 may clobber it. If the fixed area has been used for previous
4434 parameters, we must save and restore it. */
4437 }
4438 #endif
4440 /* When expanding a normal call, args are stored in push order,
4441 which is the reverse of what we have here. */
4445 {
4448 }
4452 /* Push the args that need to be pushed. */
4456 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4457 are to be pushed. */
4459 {
4468 {
4469 rtx use;
4472 {
4473 /* If this is being stored into a pre-allocated, fixed-size,
4474 stack area, save any previous data at that location. */
4477 {
4478 /* stack_slot is negative, but we want to index stack_usage_map
4479 with positive values. */
4482 }
4483 else
4484 {
4487 }
4490 reg_parm_stack_space))
4491 {
4492 /* We need to make a save area. */
4493 poly_uint64 size
4495 machine_mode save_mode
4497 rtx adr
4500 rtx stack_area
4504 {
4508 );
4512 stack_area,
4513 (gen_int_mode
4515 Pmode)),
4516 BLOCK_OP_CALL_PARM);
4517 }
4518 else
4519 {
4523 }
4524 }
4525 }
4529 (gen_int_mode
4531 reg_parm_stack_space,
4534 /* Now mark the segment we just used. */
4538 NO_DEFER_POP;
4540 /* Indicate argument access so that alias.c knows that these
4541 values are live. */
4547 else
4548 {
4549 /* When arguments are pushed, trying to tell alias.c where
4550 exactly this argument is won't work, because the
4551 auto-increment causes confusion. So we merely indicate
4552 that we access something with a known mode somewhere on
4553 the stack. */
4557 }
4561 }
4562 }
4568 /* Now load any reg parms into their regs. */
4570 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4571 are to be pushed. */
4573 {
4579 /* Handle calls that pass values in multiple non-contiguous
4580 locations. The PA64 has examples of this for library calls. */
4584 {
4586 #ifdef BLOCK_REG_PADDING
4589 /* Copied from load_register_parameters. */
4591 /* Handle case where we have a value that needs shifting
4592 up to the msb. eg. a QImode value and we're padding
4593 upward on a BYTES_BIG_ENDIAN machine. */
4597 {
4598 rtx x;
4601 /* Assigning REG here rather than a temp makes CALL_FUSAGE
4602 report the whole reg as used. Strictly speaking, the
4603 call only uses SIZE bytes at the msb end, but it doesn't
4604 seem worth generating rtl to say that. */
4609 }
4610 #endif
4611 }
4613 NO_DEFER_POP;
4614 }
4616 /* Any regs containing parms remain in use through the call. */
4618 {
4623 {
4626 {
4631 }
4632 else
4634 }
4635 }
4637 /* Pass the function the address in which to return a structure value. */
4639 {
4643 NULL_RTX)));
4646 }
4648 /* Don't allow popping to be deferred, since then
4649 cse'ing of library calls could delete a call and leave the pop. */
4650 NO_DEFER_POP;
4654 /* Stack must be properly aligned now. */
4663 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4664 will set inhibit_defer_pop to that value. */
4665 /* The return type is needed to decide how many bytes the function pops.
4666 Signedness plays no role in that, so for simplicity, we pretend it's
4667 always signed. We also assume that the list of arguments passed has
4668 no impact, so we pretend it is unknown. */
4674 struct_value_size,
4677 valreg,
4681 {
4686 }
4688 /* Right-shift returned value if necessary. */
4692 {
4695 }
4699 /* For calls to `setjmp', etc., inform function.c:setjmp_warnings
4700 that it should complain if nonvolatile values are live. For
4701 functions that cannot return, inform flow that control does not
4702 fall through. */
4704 {
4705 /* The barrier note must be emitted
4706 immediately after the CALL_INSN. Some ports emit more than
4707 just a CALL_INSN above, so we must search for it here. */
4710 {
4712 /* There was no CALL_INSN? */
4714 }
4717 }
4719 /* Consider that "regular" libcalls, i.e. all of them except for LCT_THROW
4720 and LCT_RETURNS_TWICE, cannot perform non-local gotos. */
4722 {
4725 {
4727 /* There was no CALL_INSN? */
4729 }
4732 }
4734 /* Now restore inhibit_defer_pop to its actual original value. */
4735 OK_DEFER_POP;
4739 /* Copy the value to the right place. */
4741 {
4743 {
4748 }
4750 {
4754 }
4755 else
4756 {
4757 /* Convert to the proper mode if a promotion has been active. */
4759 {
4766 }
4770 else
4772 }
4773 }
4776 {
4777 #ifdef REG_PARM_STACK_SPACE
4781 #endif
4783 /* If we saved any argument areas, restore them. */
4786 {
4795 validize_mem
4797 (gen_int_mode
4799 BLOCK_OP_CALL_PARM);
4800 else
4802 }
4807 }
4813 }
4814 \f
4816 /* Store a single argument for a function call
4817 into the register or memory area where it must be passed.
4818 *ARG describes the argument value and where to pass it.
4820 ARGBLOCK is the address of the stack-block for all the arguments,
4821 or 0 on a machine where arguments are pushed individually.
4823 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4824 so must be careful about how the stack is used.
4826 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4827 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4828 that we need not worry about saving and restoring the stack.
4830 FNDECL is the declaration of the function we are calling.
4832 Return nonzero if this arg should cause sibcall failure,
4833 zero otherwise. */
4835 static int
4838 {
4849 /* Push a new temporary level for any temporaries we make for
4850 this argument. */
4854 {
4855 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4856 save any previous data at that location. */
4858 {
4860 {
4861 /* stack_slot is negative, but we want to index stack_usage_map
4862 with positive values. */
4864 {
4867 }
4868 else
4872 }
4873 else
4874 {
4876 {
4879 }
4880 else
4884 }
4887 reg_parm_stack_space))
4888 {
4889 /* We need to make a save area. */
4891 machine_mode save_mode
4897 {
4898 arg->save_area
4902 stack_area,
4903 (gen_int_mode
4905 BLOCK_OP_CALL_PARM);
4906 }
4907 else
4908 {
4911 }
4912 }
4913 }
4914 }
4916 /* If this isn't going to be placed on both the stack and in registers,
4917 set up the register and number of words. */
4919 {
4922 else
4925 }
4927 /* Being passed entirely in a register. We shouldn't be called in
4928 this case. */
4931 /* If this arg needs special alignment, don't load the registers
4932 here. */
4936 /* If this is being passed partially in a register, we can't evaluate
4937 it directly into its stack slot. Otherwise, we can. */
4939 {
4940 /* stack_arg_under_construction is nonzero if a function argument is
4941 being evaluated directly into the outgoing argument list and
4942 expand_call must take special action to preserve the argument list
4943 if it is called recursively.
4945 For scalar function arguments stack_usage_map is sufficient to
4946 determine which stack slots must be saved and restored. Scalar
4947 arguments in general have pass_on_stack == 0.
4949 If this argument is initialized by a function which takes the
4950 address of the argument (a C++ constructor or a C function
4951 returning a BLKmode structure), then stack_usage_map is
4952 insufficient and expand_call must push the stack around the
4953 function call. Such arguments have pass_on_stack == 1.
4955 Note that it is always safe to set stack_arg_under_construction,
4956 but this generates suboptimal code if set when not needed. */
4959 stack_arg_under_construction++;
4962 (partial
4967 /* If we are promoting object (or for any other reason) the mode
4968 doesn't agree, convert the mode. */
4975 stack_arg_under_construction--;
4976 }
4978 /* Check for overlap with already clobbered argument area. */
4985 /* Don't allow anything left on stack from computation
4986 of argument to alloca. */
4991 /* If the value is already in the stack slot, we are done. */
4992 ;
4994 {
4997 /* Argument is a scalar, not entirely passed in registers.
4998 (If part is passed in registers, arg->partial says how much
4999 and emit_push_insn will take care of putting it there.)
5001 Push it, and if its size is less than the
5002 amount of space allocated to it,
5003 also bump stack pointer by the additional space.
5004 Note that in C the default argument promotions
5005 will prevent such mismatches. */
5010 /* Compute how much space the push instruction will push.
5011 On many machines, pushing a byte will advance the stack
5012 pointer by a halfword. */
5013 #ifdef PUSH_ROUNDING
5015 #endif
5018 /* Compute how much space the argument should get:
5019 round up to a multiple of the alignment for arguments. */
5022 /* At the moment we don't (need to) support ABIs for which the
5023 padding isn't known at compile time. In principle it should
5024 be easy to add though. */
5027 /* Compute the alignment of the pushed argument. */
5031 {
5036 }
5038 /* This isn't already where we want it on the stack, so put it there.
5039 This can either be done with push or copy insns. */
5044 reg_parm_stack_space,
5048 /* Unless this is a partially-in-register argument, the argument is now
5049 in the stack. */
5052 }
5053 else
5054 {
5055 /* BLKmode, at least partly to be pushed. */
5058 poly_int64 excess;
5059 rtx size_rtx;
5061 /* Pushing a nonscalar.
5062 If part is passed in registers, PARTIAL says how much
5063 and emit_push_insn will take care of putting it there. */
5065 /* Round its size up to a multiple
5066 of the allocation unit for arguments. */
5069 {
5072 }
5073 else
5074 {
5075 /* PUSH_ROUNDING has no effect on us, because emit_push_insn
5076 for BLKmode is careful to avoid it. */
5082 EXPAND_NORMAL);
5083 }
5087 /* When an argument is padded down, the block is aligned to
5088 PARM_BOUNDARY, but the actual argument isn't. */
5091 {
5094 else
5095 {
5096 unsigned int excess_align
5100 }
5101 }
5104 {
5105 /* emit_push_insn might not work properly if arg->value and
5106 argblock + arg->locate.offset areas overlap. */
5112 {
5113 /* arg.locate doesn't contain the pretend_args_size offset,
5114 it's part of argblock. Ensure we don't count it in I. */
5117 else
5120 /* expand_call should ensure this. */
5126 {
5127 /* Even though they appear to be at the same location,
5128 if part of the outgoing argument is in registers,
5129 they aren't really at the same location. Check for
5130 this by making sure that the incoming size is the
5131 same as the outgoing size. */
5134 }
5138 /* Use arg->locate.size.constant instead of size_rtx
5139 because we only care about the part of the argument
5140 on the stack. */
5144 }
5145 }
5151 reg_parm_stack_space,
5154 /* Unless this is a partially-in-register argument, the argument is now
5155 in the stack.
5157 ??? Unlike the case above, in which we want the actual
5158 address of the data, so that we can load it directly into a
5159 register, here we want the address of the stack slot, so that
5160 it's properly aligned for word-by-word copying or something
5161 like that. It's not clear that this is always correct. */
5164 }
5167 {
5169 arg->parallel_value
5172 }
5174 /* Mark all slots this store used. */
5179 /* Once we have pushed something, pops can't safely
5180 be deferred during the rest of the arguments. */
5181 NO_DEFER_POP;
5183 /* Free any temporary slots made in processing this argument. */
5187 }
5189 /* Nonzero if we do not know how to pass ARG solely in registers. */
5191 bool
5193 {
5197 /* If the type has variable size... */
5201 /* If the type is marked as addressable (it is required
5202 to be constructed into the stack)... */
5207 }
5209 /* Another version of the TARGET_MUST_PASS_IN_STACK hook. This one
5210 takes trailing padding of a structure into account. */
5211 /* ??? Should be able to merge these two by examining BLOCK_REG_PADDING. */
5213 bool
5215 {
5219 /* If the type has variable size... */
5223 /* If the type is marked as addressable (it is required
5224 to be constructed into the stack)... */
5231 /* If the padding and mode of the type is such that a copy into
5232 a register would put it into the wrong part of the register. */
5240 }
5242 /* Return true if TYPE must be passed on the stack when passed to
5243 the "..." arguments of a function. */
5245 bool
5247 {
5250 }
5252 /* Return true if FIELD is the C++17 empty base field that should
5253 be ignored for ABI calling convention decisions in order to
5254 maintain ABI compatibility between C++14 and earlier, which doesn't
5255 add this FIELD to classes with empty bases, and C++17 and later
5256 which does. */
5258 bool
5260 {
5265 }