| blob | 27b59f26ad3de061e3fbd819a520f8546972170a |
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. */
1290 /* In this loop, we consider args in the order they are written.
1291 We fill up ARGS from the back. */
1294 {
1296 call_expr_arg_iterator iter;
1297 tree arg;
1300 {
1302 j--;
1303 }
1306 {
1310 && argtype
1313 {
1316 j--;
1318 }
1319 else
1321 j--;
1322 argpos++;
1323 }
1324 }
1326 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1328 {
1332 /* Replace erroneous argument with constant zero. */
1336 /* If TYPE is a transparent union or record, pass things the way
1337 we would pass the first field of the union or record. We have
1338 already verified that the modes are the same. */
1342 /* Decide where to pass this arg.
1344 args[i].reg is nonzero if all or part is passed in registers.
1346 args[i].partial is nonzero if part but not all is passed in registers,
1347 and the exact value says how many bytes are passed in registers.
1349 args[i].pass_on_stack is nonzero if the argument must at least be
1350 computed on the stack. It may then be loaded back into registers
1351 if args[i].reg is nonzero.
1353 These decisions are driven by the FUNCTION_... macros and must agree
1354 with those made by function.c. */
1356 /* See if this argument should be passed by invisible reference. */
1359 {
1360 const bool callee_copies
1362 tree base;
1364 /* If we're compiling a thunk, pass directly the address of an object
1365 already in memory, instead of making a copy. Likewise if we want
1366 to make the copy in the callee instead of the caller. */
1372 {
1373 /* We may have turned the parameter value into an SSA name.
1374 Go back to the original parameter so we can take the
1375 address. */
1377 {
1381 }
1382 /* Argument setup code may have copied the value to register. We
1383 revert that optimization now because the tail call code must
1384 use the original location. */
1394 /* We can't use sibcalls if a callee-copied argument is
1395 stored in the current function's frame. */
1397 {
1400 "a callee-copied argument is"
1401 " stored in the current"
1403 }
1411 }
1412 else
1413 {
1414 /* We make a copy of the object and pass the address to the
1415 function being called. */
1416 rtx copy;
1423 {
1424 /* This is a variable-sized object. Make space on the stack
1425 for it. */
1429 {
1433 }
1435 /* We can pass TRUE as the 4th argument because we just
1436 saved the stack pointer and will restore it right after
1437 the call. */
1441 max_int_size_in_bytes
1446 }
1447 else
1452 /* Just change the const function to pure and then let
1453 the next test clear the pure based on
1454 callee_copies. */
1456 {
1459 }
1469 "argument must be passed"
1471 }
1473 }
1477 arg.mode
1488 /* If this is a sibling call and the machine has register windows, the
1489 register window has to be unwinded before calling the routine, so
1490 arguments have to go into the incoming registers. */
1494 else
1502 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1503 it means that we are to pass this arg in the register(s) designated
1504 by the PARALLEL, but also to pass it in the stack. */
1509 /* If this is an addressable type, we must preallocate the stack
1510 since we must evaluate the object into its final location.
1512 If this is to be passed in both registers and the stack, it is simpler
1513 to preallocate. */
1518 /* Compute the stack-size of this argument. */
1523 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1525 #else
1527 #endif
1528 reg_parm_stack_space,
1531 #ifdef BLOCK_REG_PADDING
1532 else
1533 /* The argument is passed entirely in registers. See at which
1534 end it should be padded. */
1538 #endif
1540 /* Update ARGS_SIZE, the total stack space for args so far. */
1546 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1547 have been used, etc. */
1549 /* ??? Traditionally we've passed TYPE_MODE here, instead of the
1550 promoted_mode used for function_arg above. However, the
1551 corresponding handling of incoming arguments in function.c
1552 does pass the promoted mode. */
1555 }
1556 }
1558 /* Update ARGS_SIZE to contain the total size for the argument block.
1559 Return the original constant component of the argument block's size.
1561 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1562 for arguments passed in registers. */
1564 static poly_int64
1567 tree fndecl ATTRIBUTE_UNUSED,
1568 tree fntype ATTRIBUTE_UNUSED,
1570 {
1573 /* For accumulate outgoing args mode we don't need to align, since the frame
1574 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1575 backends from generating misaligned frame sizes. */
1579 /* Compute the actual size of the argument block required. The variable
1580 and constant sizes must be combined, the size may have to be rounded,
1581 and there may be a minimum required size. */
1584 {
1590 {
1591 /* We don't handle this case yet. To handle it correctly we have
1592 to add the delta, round and subtract the delta.
1593 Currently no machine description requires this support. */
1595 preferred_stack_boundary));
1597 }
1600 {
1601 args_size->var
1605 /* The area corresponding to register parameters is not to count in
1606 the size of the block we need. So make the adjustment. */
1608 args_size->var
1611 }
1612 }
1613 else
1614 {
1620 preferred_stack_boundary)
1624 reg_parm_stack_space);
1628 }
1630 }
1632 /* Precompute parameters as needed for a function call.
1634 FLAGS is mask of ECF_* constants.
1636 NUM_ACTUALS is the number of arguments.
1638 ARGS is an array containing information for each argument; this
1639 routine fills in the INITIAL_VALUE and VALUE fields for each
1640 precomputed argument. */
1642 static void
1644 {
1647 /* If this is a libcall, then precompute all arguments so that we do not
1648 get extraneous instructions emitted as part of the libcall sequence. */
1650 /* If we preallocated the stack space, and some arguments must be passed
1651 on the stack, then we must precompute any parameter which contains a
1652 function call which will store arguments on the stack.
1653 Otherwise, evaluating the parameter may clobber previous parameters
1654 which have already been stored into the stack. (we have code to avoid
1655 such case by saving the outgoing stack arguments, but it results in
1656 worse code) */
1661 {
1662 tree type;
1663 machine_mode mode;
1668 /* If this is an addressable type, we cannot pre-evaluate it. */
1677 {
1683 /* CSE will replace this only if it contains args[i].value
1684 pseudo, so convert it down to the declared mode using
1685 a SUBREG. */
1689 {
1694 }
1695 }
1696 }
1697 }
1699 /* Given the current state of MUST_PREALLOCATE and information about
1700 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1701 compute and return the final value for MUST_PREALLOCATE. */
1703 static int
1706 {
1707 /* See if we have or want to preallocate stack space.
1709 If we would have to push a partially-in-regs parm
1710 before other stack parms, preallocate stack space instead.
1712 If the size of some parm is not a multiple of the required stack
1713 alignment, we must preallocate.
1715 If the total size of arguments that would otherwise create a copy in
1716 a temporary (such as a CALL) is more than half the total argument list
1717 size, preallocation is faster.
1719 Another reason to preallocate is if we have a machine (like the m88k)
1720 where stack alignment is required to be maintained between every
1721 pair of insns, not just when the call is made. However, we assume here
1722 that such machines either do not have push insns (and hence preallocation
1723 would occur anyway) or the problem is taken care of with
1724 PUSH_ROUNDING. */
1727 {
1733 {
1744 copy_to_evaluate_size
1746 }
1751 }
1753 }
1755 /* If we preallocated stack space, compute the address of each argument
1756 and store it into the ARGS array.
1758 We need not ensure it is a valid memory address here; it will be
1759 validized when it is used.
1761 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1763 static void
1765 {
1767 {
1773 {
1776 }
1779 {
1782 rtx addr;
1787 /* Skip this parm if it will not be passed on the stack. */
1800 {
1801 /* Only part of the parameter is being passed on the stack.
1802 Generate a simple memory reference of the correct size. */
1808 }
1809 else
1810 {
1814 }
1817 poly_int64 offset_val;
1821 {
1823 unsigned int offset_align
1827 }
1834 {
1835 /* Only part of the parameter is being passed on the stack.
1836 Generate a simple memory reference of the correct size.
1837 */
1840 }
1841 else
1842 {
1846 }
1849 /* Function incoming arguments may overlap with sibling call
1850 outgoing arguments and we cannot allow reordering of reads
1851 from function arguments with stores to outgoing arguments
1852 of sibling calls. */
1855 }
1856 }
1857 }
1859 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1860 in a call instruction.
1862 FNDECL is the tree node for the target function. For an indirect call
1863 FNDECL will be NULL_TREE.
1865 ADDR is the operand 0 of CALL_EXPR for this call. */
1867 static rtx
1869 {
1870 rtx funexp;
1872 /* Get the function to call, in the form of RTL. */
1874 {
1878 /* Get a SYMBOL_REF rtx for the function address. */
1880 }
1881 else
1882 /* Generate an rtx (probably a pseudo-register) for the address. */
1883 {
1887 }
1889 }
1891 /* Return the static chain for this function, if any. */
1893 rtx
1895 {
1900 }
1902 /* Internal state for internal_arg_pointer_based_exp and its helpers. */
1903 static struct
1904 {
1905 /* Last insn that has been scanned by internal_arg_pointer_based_exp_scan,
1906 or NULL_RTX if none has been scanned yet. */
1908 /* Vector indexed by REGNO - FIRST_PSEUDO_REGISTER, recording if a pseudo is
1909 based on crtl->args.internal_arg_pointer. The element is NULL_RTX if the
1910 pseudo isn't based on it, a CONST_INT offset if the pseudo is based on it
1911 with fixed offset, or PC if this is with variable or unknown offset. */
1917 /* Helper function for internal_arg_pointer_based_exp. Scan insns in
1918 the tail call sequence, starting with first insn that hasn't been
1919 scanned yet, and note for each pseudo on the LHS whether it is based
1920 on crtl->args.internal_arg_pointer or not, and what offset from that
1921 that pointer it has. */
1923 static void
1925 {
1930 else
1934 {
1937 {
1940 /* Punt on pseudos set multiple times. */
1945 else
1948 {
1950 internal_arg_pointer_exp_state.cache
1953 }
1954 }
1958 }
1961 }
1963 /* Compute whether RTL is based on crtl->args.internal_arg_pointer. Return
1964 NULL_RTX if RTL isn't based on it, a CONST_INT offset if RTL is based on
1965 it with fixed offset, or PC if this is with variable or unknown offset.
1966 TOPLEVEL is true if the function is invoked at the topmost level. */
1968 static rtx
1970 {
1980 poly_int64 offset;
1982 {
1987 }
1989 /* When called at the topmost level, scan pseudo assignments in between the
1990 last scanned instruction in the tail call sequence and the latest insn
1991 in that sequence. */
1996 {
2002 }
2006 {
2012 }
2015 }
2017 /* Return true if SIZE bytes starting from address ADDR might overlap an
2018 already-clobbered argument area. This function is used to determine
2019 if we should give up a sibcall. */
2021 static bool
2023 {
2024 poly_int64 i;
2026 rtx val;
2042 else
2048 /* We can ignore any references to the function's pretend args,
2049 which at this point would manifest as negative values of I. */
2066 }
2068 /* Do the register loads required for any wholly-register parms or any
2069 parms which are passed both on the stack and in a register. Their
2070 expressions were already evaluated.
2072 Mark all register-parms as living through the call, putting these USE
2073 insns in the CALL_INSN_FUNCTION_USAGE field.
2075 When IS_SIBCALL, perform the check_sibcall_argument_overlap
2076 checking, setting *SIBCALL_FAILURE if appropriate. */
2078 static void
2082 {
2086 {
2090 {
2099 /* Set non-negative if we must move a word at a time, even if
2100 just one word (e.g, partial == 4 && mode == DFmode). Set
2101 to -1 if we just use a normal move insn. This value can be
2102 zero if the argument is a zero size structure. */
2105 ;
2107 {
2110 }
2112 {
2113 /* Variable-sized parameters should be described by a
2114 PARALLEL instead. */
2119 }
2120 else
2123 /* Handle calls that pass values in multiple non-contiguous
2124 locations. The Irix 6 ABI has examples of this. */
2129 /* If simple case, just do move. If normal partial, store_one_arg
2130 has already loaded the register for us. In all other cases,
2131 load the register(s) from memory. */
2134 {
2136 #ifdef BLOCK_REG_PADDING
2137 /* Handle case where we have a value that needs shifting
2138 up to the msb. eg. a QImode value and we're padding
2139 upward on a BYTES_BIG_ENDIAN machine. */
2142 {
2145 {
2146 rtx x;
2147 poly_int64 shift
2150 /* Assigning REG here rather than a temp makes
2151 CALL_FUSAGE report the whole reg as used.
2152 Strictly speaking, the call only uses SIZE
2153 bytes at the msb end, but it doesn't seem worth
2154 generating rtl to say that. */
2160 }
2161 }
2162 #endif
2163 }
2165 /* If we have pre-computed the values to put in the registers in
2166 the case of non-aligned structures, copy them in now. */
2174 {
2175 /* SIZE and CONST_SIZE are 0 for partial arguments and
2176 the size of a BLKmode type otherwise. */
2180 /* Check for overlap with already clobbered argument area,
2181 providing that this has non-zero size. */
2184 && (mem_might_overlap_already_clobbered_arg_p
2191 else
2192 {
2201 NULL);
2207 }
2209 /* Handle a BLKmode that needs shifting. */
2211 #ifdef BLOCK_REG_PADDING
2213 #else
2214 && BYTES_BIG_ENDIAN
2215 #endif
2216 )
2217 {
2222 rtx x;
2227 }
2228 }
2230 /* When a parameter is a block, and perhaps in other cases, it is
2231 possible that it did a load from an argument slot that was
2232 already clobbered. */
2237 /* Handle calls that pass values in multiple non-contiguous
2238 locations. The Irix 6 ABI has examples of this. */
2245 }
2246 }
2247 }
2249 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
2250 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
2251 bytes, then we would need to push some additional bytes to pad the
2252 arguments. So, we try to compute an adjust to the stack pointer for an
2253 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
2254 bytes. Then, when the arguments are pushed the stack will be perfectly
2255 aligned.
2257 Return true if this optimization is possible, storing the adjustment
2258 in ADJUSTMENT_OUT and setting ARGS_SIZE->CONSTANT to the number of
2259 bytes that should be popped after the call. */
2261 static bool
2263 poly_int64 unadjusted_args_size,
2266 {
2267 /* The number of bytes to pop so that the stack will be
2268 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
2269 poly_int64 adjustment;
2270 /* The alignment of the stack after the arguments are pushed, if we
2271 just pushed the arguments without adjust the stack here. */
2275 preferred_unit_stack_boundary,
2279 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
2280 as possible -- leaving just enough left to cancel out the
2281 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
2282 PENDING_STACK_ADJUST is non-negative, and congruent to
2283 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
2285 /* Begin by trying to pop all the bytes. */
2288 preferred_unit_stack_boundary,
2293 /* Push enough additional bytes that the stack will be aligned
2294 after the arguments are pushed. */
2298 /* We need to know whether the adjusted argument size
2299 (UNADJUSTED_ARGS_SIZE - ADJUSTMENT) constitutes an allocation
2300 or a deallocation. */
2304 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
2305 bytes after the call. The right number is the entire
2306 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
2307 by the arguments in the first place. */
2308 args_size->constant
2313 }
2315 /* Scan X expression if it does not dereference any argument slots
2316 we already clobbered by tail call arguments (as noted in stored_args_map
2317 bitmap).
2318 Return nonzero if X expression dereferences such argument slots,
2319 zero otherwise. */
2321 static int
2323 {
2324 RTX_CODE code;
2333 /* We need not check the operands of the CALL expression itself. */
2341 /* Scan all subexpressions. */
2344 {
2346 {
2349 }
2351 {
2355 }
2356 }
2358 }
2360 /* Scan sequence after INSN if it does not dereference any argument slots
2361 we already clobbered by tail call arguments (as noted in stored_args_map
2362 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
2363 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
2364 should be 0). Return nonzero if sequence after INSN dereferences such argument
2365 slots, zero otherwise. */
2367 static int
2370 {
2376 else
2385 {
2388 else
2396 else
2398 }
2400 }
2402 /* Given that a function returns a value of mode MODE at the most
2403 significant end of hard register VALUE, shift VALUE left or right
2404 as specified by LEFT_P. Return true if some action was needed. */
2406 bool
2408 {
2416 /* Use ashr rather than lshr for right shifts. This is for the benefit
2417 of the MIPS port, which requires SImode values to be sign-extended
2418 when stored in 64-bit registers. */
2424 }
2426 /* If X is a likely-spilled register value, copy it to a pseudo
2427 register and return that register. Return X otherwise. */
2429 static rtx
2431 {
2432 rtx new_rtx;
2437 {
2438 /* Make sure that we generate a REG rather than a CONCAT.
2439 Moves into CONCATs can need nontrivial instructions,
2440 and the whole point of this function is to avoid
2441 using the hard register directly in such a situation. */
2447 }
2449 }
2451 /* Helper function for expand_call.
2452 Return false is EXP is not implementable as a sibling call. */
2454 static bool
2456 rtx structure_value_addr,
2457 tree funtype,
2458 tree fndecl,
2460 tree addr,
2462 {
2464 {
2465 maybe_complain_about_tail_call
2467 "machine description does not have"
2470 }
2472 /* Doing sibling call optimization needs some work, since
2473 structure_value_addr can be allocated on the stack.
2474 It does not seem worth the effort since few optimizable
2475 sibling calls will return a structure. */
2477 {
2480 }
2482 /* Check whether the target is able to optimize the call
2483 into a sibcall. */
2485 {
2487 "target is not able to optimize the"
2490 }
2492 /* Functions that do not return exactly once may not be sibcall
2493 optimized. */
2495 {
2498 }
2500 {
2503 }
2506 {
2509 }
2511 /* If the called function is nested in the current one, it might access
2512 some of the caller's arguments, but could clobber them beforehand if
2513 the argument areas are shared. */
2515 {
2518 }
2520 /* If this function requires more stack slots than the current
2521 function, we cannot change it into a sibling call.
2522 crtl->args.pretend_args_size is not part of the
2523 stack allocated by our caller. */
2526 {
2528 "callee required more stack slots"
2531 }
2533 /* If the callee pops its own arguments, then it must pop exactly
2534 the same number of arguments as the current function. */
2538 TREE_TYPE
2541 {
2543 "inconsistent number of"
2546 }
2549 {
2553 }
2555 /* All checks passed. */
2557 }
2559 /* Update stack alignment when the parameter is passed in the stack
2560 since the outgoing parameter requires extra alignment on the calling
2561 function side. */
2563 static void
2565 {
2570 }
2572 /* Generate all the code for a CALL_EXPR exp
2573 and return an rtx for its value.
2574 Store the value in TARGET (specified as an rtx) if convenient.
2575 If the value is stored in TARGET then TARGET is returned.
2576 If IGNORE is nonzero, then we ignore the value of the function call. */
2578 rtx
2580 {
2581 /* Nonzero if we are currently expanding a call. */
2584 /* RTX for the function to be called. */
2585 rtx funexp;
2586 /* Sequence of insns to perform a normal "call". */
2588 /* Sequence of insns to perform a tail "call". */
2590 /* Data type of the function. */
2591 tree funtype;
2592 tree type_arg_types;
2593 tree rettype;
2594 /* Declaration of the function being called,
2595 or 0 if the function is computed (not known by name). */
2597 /* The type of the function being called. */
2598 tree fntype;
2603 /* Register in which non-BLKmode value will be returned,
2604 or 0 if no value or if value is BLKmode. */
2605 rtx valreg;
2606 /* Address where we should return a BLKmode value;
2607 0 if value not BLKmode. */
2609 /* Nonzero if that address is being passed by treating it as
2610 an extra, implicit first parameter. Otherwise,
2611 it is passed by being copied directly into struct_value_rtx. */
2613 /* Holds the value of implicit argument for the struct value. */
2615 /* Size of aggregate value wanted, or zero if none wanted
2616 or if we are using the non-reentrant PCC calling convention
2617 or expecting the value in registers. */
2619 /* Nonzero if called function returns an aggregate in memory PCC style,
2620 by returning the address of where to find it. */
2624 /* Number of actual parameters in this call, including struct value addr. */
2626 /* Number of named args. Args after this are anonymous ones
2627 and they must all go on the stack. */
2629 /* Number of complex actual arguments that need to be split. */
2632 /* Vector of information about each argument.
2633 Arguments are numbered in the order they will be pushed,
2634 not the order they are written. */
2637 /* Total size in bytes of all the stack-parms scanned so far. */
2640 /* Size of arguments before any adjustments (such as rounding). */
2641 poly_int64 unadjusted_args_size;
2642 /* Data on reg parms scanned so far. */
2643 CUMULATIVE_ARGS args_so_far_v;
2644 cumulative_args_t args_so_far;
2645 /* Nonzero if a reg parm has been scanned. */
2647 /* Nonzero if this is an indirect function call. */
2649 /* Nonzero if we must avoid push-insns in the args for this call.
2650 If stack space is allocated for register parameters, but not by the
2651 caller, then it is preallocated in the fixed part of the stack frame.
2652 So the entire argument block must then be preallocated (i.e., we
2653 ignore PUSH_ROUNDING in that case). */
2657 /* Size of the stack reserved for parameter registers. */
2660 /* Address of space preallocated for stack parms
2661 (on machines that lack push insns), or 0 if space not preallocated. */
2664 /* Mask of ECF_ and ERF_ flags. */
2667 #ifdef REG_PARM_STACK_SPACE
2668 /* Define the boundary of the register parm stack space that needs to be
2669 saved, if any. */
2672 #endif
2679 poly_int64 old_stack_allocated;
2681 /* State variables to track stack modifications. */
2687 /* Some stack pointer alterations we make are performed via
2688 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2689 which we then also need to save/restore along the way. */
2692 rtx call_fusage;
2695 /* The alignment of the stack, in bits. */
2697 /* The alignment of the stack, in bytes. */
2699 /* The static chain value to use for this call. */
2700 rtx static_chain_value;
2701 /* See if this is "nothrow" function call. */
2705 /* See if we can find a DECL-node for the actual function, and get the
2706 function attributes (flags) from the function decl or type node. */
2709 {
2713 }
2714 else
2715 {
2720 }
2725 /* Warn if this value is an aggregate type,
2726 regardless of which calling convention we are using for it. */
2730 /* If the result of a non looping pure or const function call is
2731 ignored (or void), and none of its arguments are volatile, we can
2732 avoid expanding the call and just evaluate the arguments for
2733 side-effects. */
2739 {
2741 tree arg;
2742 call_expr_arg_iterator iter;
2746 {
2749 }
2752 {
2756 }
2757 }
2759 #ifdef REG_PARM_STACK_SPACE
2761 #endif
2767 /* Set up a place to return a structure. */
2769 /* Cater to broken compilers. */
2771 {
2772 /* This call returns a big structure. */
2775 #ifdef PCC_STATIC_STRUCT_RETURN
2776 {
2778 }
2780 {
2784 /* Even if it is semantically safe to use the target as the return
2785 slot, it may be not sufficiently aligned for the return type. */
2787 && target
2789 /* If rettype is addressable, we may not create a temporary.
2790 If target is properly aligned at runtime and the compiler
2791 just doesn't know about it, it will work fine, otherwise it
2792 will be UB. */
2798 else
2799 {
2800 /* For variable-sized objects, we must be called with a target
2801 specified. If we were to allocate space on the stack here,
2802 we would have no way of knowing when to free it. */
2806 }
2807 }
2809 }
2811 /* Figure out the amount to which the stack should be aligned. */
2814 {
2816 /* Without automatic stack alignment, we can't increase preferred
2817 stack boundary. With automatic stack alignment, it is
2818 unnecessary since unless we can guarantee that all callers will
2819 align the outgoing stack properly, callee has to align its
2820 stack anyway. */
2825 }
2827 /* Operand 0 is a pointer-to-function; get the type of the function. */
2832 /* Count whether there are actual complex arguments that need to be split
2833 into their real and imaginary parts. Munge the type_arg_types
2834 appropriately here as well. */
2836 {
2837 call_expr_arg_iterator iter;
2838 tree arg;
2840 {
2844 num_complex_actuals++;
2845 }
2847 }
2848 else
2854 /* If struct_value_rtx is 0, it means pass the address
2855 as if it were an extra parameter. Put the argument expression
2856 in structure_value_addr_value. */
2858 {
2859 /* If structure_value_addr is a REG other than
2860 virtual_outgoing_args_rtx, we can use always use it. If it
2861 is not a REG, we must always copy it into a register.
2862 If it is virtual_outgoing_args_rtx, we must copy it to another
2863 register in some cases. */
2865 || (ACCUMULATE_OUTGOING_ARGS
2866 && stack_arg_under_construction
2872 structure_value_addr_value =
2875 }
2877 /* Count the arguments and set NUM_ACTUALS. */
2878 num_actuals =
2881 /* Compute number of named args.
2882 First, do a raw count of the args for INIT_CUMULATIVE_ARGS. */
2885 n_named_args
2887 /* Count the struct value address, if it is passed as a parm. */
2889 else
2890 /* If we know nothing, treat all args as named. */
2893 /* Start updating where the next arg would go.
2895 On some machines (such as the PA) indirect calls have a different
2896 calling convention than normal calls. The fourth argument in
2897 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2898 or not. */
2902 /* Now possibly adjust the number of named args.
2903 Normally, don't include the last named arg if anonymous args follow.
2904 We do include the last named arg if
2905 targetm.calls.strict_argument_naming() returns nonzero.
2906 (If no anonymous args follow, the result of list_length is actually
2907 one too large. This is harmless.)
2909 If targetm.calls.pretend_outgoing_varargs_named() returns
2910 nonzero, and targetm.calls.strict_argument_naming() returns zero,
2911 this machine will be able to place unnamed args that were passed
2912 in registers into the stack. So treat all args as named. This
2913 allows the insns emitting for a specific argument list to be
2914 independent of the function declaration.
2916 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
2917 we do not have any reliable way to pass unnamed args in
2918 registers, so we must force them into memory. */
2922 ;
2925 /* Don't include the last named arg. */
2927 else
2928 /* Treat all args as named. */
2931 /* Make a vector to hold all the information about each arg. */
2934 /* Build up entries in the ARGS array, compute the size of the
2935 arguments into ARGS_SIZE, etc. */
2947 /* Now make final decision about preallocating stack space. */
2952 /* If the structure value address will reference the stack pointer, we
2953 must stabilize it. We don't need to do this if we know that we are
2954 not going to adjust the stack pointer in processing this call. */
2959 structure_value_addr))
2961 || (!ACCUMULATE_OUTGOING_ARGS
2965 /* Tail calls can make things harder to debug, and we've traditionally
2966 pushed these optimizations into -O2. Don't try if we're already
2967 expanding a call, as that means we're an argument. Don't try if
2968 there's cleanups, as we know there's code to follow the call. */
2975 /* Workaround buggy C/C++ wrappers around Fortran routines with
2976 character(len=constant) arguments if the hidden string length arguments
2977 are passed on the stack; if the callers forget to pass those arguments,
2978 attempting to tail call in such routines leads to stack corruption.
2979 Avoid tail calls in functions where at least one such hidden string
2980 length argument is passed (partially or fully) on the stack in the
2981 caller and the callee needs to pass any arguments on the stack.
2982 See PR90329. */
2987 {
2991 {
2994 }
2995 }
2997 /* If the user has marked the function as requiring tail-call
2998 optimization, attempt it. */
3002 /* Rest of purposes for tail call optimizations to fail. */
3005 structure_value_addr,
3006 funtype,
3007 fndecl,
3010 /* Check if caller and callee disagree in promotion of function
3011 return value. */
3013 {
3023 caller_promoted_mode
3027 callee_promoted_mode
3037 {
3040 "caller and callee disagree in"
3041 " promotion of function"
3043 }
3044 }
3046 /* Ensure current function's preferred stack boundary is at least
3047 what we need. Stack alignment may also increase preferred stack
3048 boundary. */
3057 else
3065 /* We want to make two insn chains; one for a sibling call, the other
3066 for a normal call. We will select one of the two chains after
3067 initial RTL generation is complete. */
3069 {
3071 /* We want to emit any pending stack adjustments before the tail
3072 recursion "call". That way we know any adjustment after the tail
3073 recursion call can be ignored if we indeed use the tail
3074 call expansion. */
3075 saved_pending_stack_adjust save;
3077 rtx next_arg_reg;
3080 {
3081 /* State variables we need to save and restore between
3082 iterations. */
3084 }
3087 else
3090 /* Other state variables that we must reinitialize each time
3091 through the loop (that are not initialized by the loop itself). */
3095 /* Start a new sequence for the normal call case.
3097 From this point on, if the sibling call fails, we want to set
3098 sibcall_failure instead of continuing the loop. */
3101 /* Don't let pending stack adjusts add up to too much.
3102 Also, do all pending adjustments now if there is any chance
3103 this might be a call to alloca or if we are expanding a sibling
3104 call sequence.
3105 Also do the adjustments before a throwing call, otherwise
3106 exception handling can fail; PR 19225. */
3115 /* Precompute any arguments as needed. */
3119 /* Now we are about to start emitting insns that can be deleted
3120 if a libcall is deleted. */
3130 /* Compute the actual size of the argument block required. The variable
3131 and constant sizes must be combined, the size may have to be rounded,
3132 and there may be a minimum required size. When generating a sibcall
3133 pattern, do not round up, since we'll be re-using whatever space our
3134 caller provided. */
3135 unadjusted_args_size
3144 /* The argument block when performing a sibling call is the
3145 incoming argument block. */
3147 {
3150 argblock
3152 else
3153 argblock
3160 }
3162 /* If we have no actual push instructions, or shouldn't use them,
3163 make space for all args right now. */
3165 {
3167 {
3172 /* stack_arg_under_construction says whether a stack arg is
3173 being constructed at the old stack level. Pushing the stack
3174 gets a clean outgoing argument block. */
3177 }
3181 }
3182 else
3183 {
3184 /* Note that we must go through the motions of allocating an argument
3185 block even if the size is zero because we may be storing args
3186 in the area reserved for register arguments, which may be part of
3187 the stack frame. */
3191 /* Store the maximum argument space used. It will be pushed by
3192 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
3193 checking). */
3196 needed);
3199 {
3201 {
3202 /* Since the stack pointer will never be pushed, it is
3203 possible for the evaluation of a parm to clobber
3204 something we have already written to the stack.
3205 Since most function calls on RISC machines do not use
3206 the stack, this is uncommon, but must work correctly.
3208 Therefore, we save any area of the stack that was already
3209 written and that we are using. Here we set up to do this
3210 by making a new stack usage map from the old one. The
3211 actual save will be done by store_one_arg.
3213 Another approach might be to try to reorder the argument
3214 evaluations to avoid this conflicting stack usage. */
3216 /* Since we will be writing into the entire argument area,
3217 the map must be allocated for its entire size, not just
3218 the part that is the responsibility of the caller. */
3226 /* For polynomial sizes, this is the maximum possible
3227 size needed for arguments with a constant size
3228 and offset. */
3230 highest_outgoing_arg_in_use
3239 initial_highest_arg_in_use);
3243 (highest_outgoing_arg_in_use
3247 /* The address of the outgoing argument list must not be
3248 copied to a register here, because argblock would be left
3249 pointing to the wrong place after the call to
3250 allocate_dynamic_stack_space below. */
3253 }
3254 else
3255 {
3256 /* Try to reuse some or all of the pending_stack_adjust
3257 to get this space. */
3259 && (combine_pending_stack_adjustment_and_call
3261 unadjusted_args_size,
3263 preferred_unit_stack_boundary)))
3264 {
3265 /* combine_pending_stack_adjustment_and_call computes
3266 an adjustment before the arguments are allocated.
3267 Account for them and see whether or not the stack
3268 needs to go up or down. */
3271 /* Checked by
3272 combine_pending_stack_adjustment_and_call. */
3275 {
3276 /* We're releasing stack space. */
3277 /* ??? We can avoid any adjustment at all if we're
3278 already aligned. FIXME. */
3282 }
3283 else
3284 /* We need to allocate space. We'll do that in
3285 push_block below. */
3287 }
3289 /* Special case this because overhead of `push_block' in
3290 this case is non-trivial. */
3293 else
3294 {
3299 }
3301 /* We only really need to call `copy_to_reg' in the case
3302 where push insns are going to be used to pass ARGBLOCK
3303 to a function call in ARGS. In that case, the stack
3304 pointer changes value from the allocation point to the
3305 call point, and hence the value of
3306 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
3307 as well always do it. */
3309 }
3310 }
3311 }
3314 {
3315 /* The save/restore code in store_one_arg handles all
3316 cases except one: a constructor call (including a C
3317 function returning a BLKmode struct) to initialize
3318 an argument. */
3320 {
3321 rtx push_size
3322 = (gen_int_mode
3328 {
3333 /* stack_arg_under_construction says whether a stack
3334 arg is being constructed at the old stack level.
3335 Pushing the stack gets a clean outgoing argument
3336 block. */
3337 old_stack_arg_under_construction
3340 /* Make a new map for the new argument list. */
3346 }
3347 /* We can pass TRUE as the 4th argument because we just
3348 saved the stack pointer and will restore it right after
3349 the call. */
3352 }
3354 /* If argument evaluation might modify the stack pointer,
3355 copy the address of the argument list to a register. */
3358 {
3361 }
3362 }
3366 /* Stack is properly aligned, pops can't safely be deferred during
3367 the evaluation of the arguments. */
3368 NO_DEFER_POP;
3370 /* Precompute all register parameters. It isn't safe to compute
3371 anything once we have started filling any specific hard regs.
3372 TLS symbols sometimes need a call to resolve. Precompute
3373 register parameters before any stack pointer manipulation
3374 to avoid unaligned stack in the called function. */
3377 OK_DEFER_POP;
3379 /* Perform stack alignment before the first push (the last arg). */
3383 {
3384 /* When the stack adjustment is pending, we get better code
3385 by combining the adjustments. */
3387 && ! inhibit_defer_pop
3388 && (combine_pending_stack_adjustment_and_call
3390 unadjusted_args_size,
3392 preferred_unit_stack_boundary)))
3397 Pmode));
3398 }
3399 /* Now that the stack is properly aligned, pops can't safely
3400 be deferred during the evaluation of the arguments. */
3401 NO_DEFER_POP;
3403 /* Record the maximum pushed stack space size. We need to delay
3404 doing it this far to take into account the optimization done
3405 by combine_pending_stack_adjustment_and_call. */
3407 && !ACCUMULATE_OUTGOING_ARGS
3408 && pass
3410 {
3413 current_function_pushed_stack_size
3415 }
3421 else
3424 #ifdef REG_PARM_STACK_SPACE
3425 /* Save the fixed argument area if it's part of the caller's frame and
3426 is clobbered by argument setup for this call. */
3430 #endif
3432 /* Now store (and compute if necessary) all non-register parms.
3433 These come before register parms, since they can require block-moves,
3434 which could clobber the registers used for register parms.
3435 Parms which have partial registers are not stored here,
3436 but we do preallocate space here if they want that. */
3439 {
3441 {
3444 /* We don't allow passing huge (> 2^30 B) arguments
3445 by value. It would cause an overflow later on. */
3448 {
3451 }
3455 reg_parm_stack_space)
3460 }
3463 call_fusage
3466 call_fusage);
3467 }
3469 /* If we have a parm that is passed in registers but not in memory
3470 and whose alignment does not permit a direct copy into registers,
3471 make a group of pseudos that correspond to each register that we
3472 will later fill. */
3476 /* Now store any partially-in-registers parm.
3477 This is the last place a block-move can happen. */
3481 {
3484 /* On targets with weird calling conventions (e.g. PA) it's
3485 hard to ensure that all cases of argument overlap between
3486 stack and registers work. Play it safe and bail out. */
3488 {
3491 }
3495 reg_parm_stack_space)
3500 }
3505 {
3508 }
3512 /* Figure out the register where the value, if any, will come back. */
3516 {
3520 else
3524 /* If VALREG is a PARALLEL whose first member has a zero
3525 offset, use that. This is for targets such as m68k that
3526 return the same value in multiple places. */
3528 {
3535 }
3536 }
3538 /* If register arguments require space on the stack and stack space
3539 was not preallocated, allocate stack space here for arguments
3540 passed in registers. */
3542 && !ACCUMULATE_OUTGOING_ARGS
3546 /* Pass the function the address in which to return a
3547 structure value. */
3549 {
3550 structure_value_addr
3555 NULL_RTX)));
3559 }
3569 /* Save a pointer to the last insn before the call, so that we can
3570 later safely search backwards to find the CALL_INSN. */
3573 /* Set up next argument register. For sibling calls on machines
3574 with register windows this should be the incoming register. */
3578 else
3583 {
3589 && valreg
3592 call_fusage
3595 call_fusage);
3596 }
3597 /* All arguments and registers used for the call must be set up by
3598 now! */
3600 /* Stack must be properly aligned now. */
3603 preferred_unit_stack_boundary));
3605 /* Generate the actual call instruction. */
3612 {
3616 {
3620 }
3623 }
3625 /* If the call setup or the call itself overlaps with anything
3626 of the argument setup we probably clobbered our call address.
3627 In that case we can't do sibcalls. */
3632 /* If a non-BLKmode value is returned at the most significant end
3633 of a register, shift the register right by the appropriate amount
3634 and update VALREG accordingly. BLKmode values are handled by the
3635 group load/store machinery below. */
3637 && !pcc_struct_value
3642 {
3646 }
3649 {
3653 /* The return value from a malloc-like function is a pointer. */
3659 /* The return value from a malloc-like function cannot alias
3660 anything else. */
3664 /* Write out the sequence. */
3669 }
3671 /* For calls to `setjmp', etc., inform
3672 function.c:setjmp_warnings that it should complain if
3673 nonvolatile values are live. For functions that cannot
3674 return, inform flow that control does not fall through. */
3677 {
3678 /* The barrier must be emitted
3679 immediately after the CALL_INSN. Some ports emit more
3680 than just a CALL_INSN above, so we must search for it here. */
3684 {
3686 /* There was no CALL_INSN? */
3688 }
3692 /* Stack adjustments after a noreturn call are dead code.
3693 However when NO_DEFER_POP is in effect, we must preserve
3694 stack_pointer_delta. */
3696 {
3699 }
3700 }
3702 /* If value type not void, return an rtx for the value. */
3708 {
3710 {
3711 target
3714 structure_value_addr));
3716 }
3717 }
3719 {
3720 /* This is the special C++ case where we need to
3721 know what the true target was. We take care to
3722 never use this value more than once in one expression. */
3726 }
3727 /* Handle calls that return values in multiple non-contiguous locations.
3728 The Irix 6 ABI has examples of this. */
3730 {
3734 ;
3736 /* Handle the result of a emit_group_move_into_temps
3737 call in the previous pass. */
3739 else
3742 }
3746 {
3749 /* We have to copy a return value in a CLASS_LIKELY_SPILLED hard
3750 reg to a plain register. */
3754 /* If TARGET is a MEM in the argument area, and we have
3755 saved part of the argument area, then we can't store
3756 directly into TARGET as it may get overwritten when we
3757 restore the argument save area below. Don't work too
3758 hard though and simply force TARGET to a register if it
3759 is a MEM; the optimizer is quite likely to sort it out. */
3763 {
3766 }
3770 else
3771 {
3772 /* TARGET and VALREG cannot be equal at this point
3773 because the latter would not have
3774 REG_FUNCTION_VALUE_P true, while the former would if
3775 it were referring to the same register.
3777 If they refer to the same register, this move will be
3778 a no-op, except when function inlining is being
3779 done. */
3782 /* If we are setting a MEM, this code must be executed.
3783 Since it is emitted after the call insn, sibcall
3784 optimization cannot be performed in that case. */
3787 }
3788 }
3789 else
3792 /* If we promoted this return value, make the proper SUBREG.
3793 TARGET might be const0_rtx here, so be careful. */
3797 {
3800 machine_mode pmode;
3802 /* Ensure we promote as expected, and get the new unsignedness. */
3812 }
3814 /* If size of args is variable or this was a constructor call for a stack
3815 argument, restore saved stack-pointer value. */
3818 {
3833 }
3835 {
3836 #ifdef REG_PARM_STACK_SPACE
3840 #endif
3842 /* If we saved any argument areas, restore them. */
3845 {
3847 rtx stack_area
3854 else
3856 (gen_int_mode
3858 BLOCK_OP_CALL_PARM);
3859 }
3864 }
3866 /* If this was alloca, record the new stack level. */
3870 /* Free up storage we no longer need. */
3880 {
3883 /* Restore the pending stack adjustment now that we have
3884 finished generating the sibling call sequence. */
3888 /* Prepare arg structure for next iteration. */
3890 {
3894 }
3899 }
3900 else
3901 {
3904 /* Verify that we've deallocated all the stack we used. */
3907 stack_pointer_delta
3909 }
3911 /* If something prevents making this a sibling call,
3912 zero out the sequence. */
3915 else
3917 }
3919 /* If tail call production succeeded, we need to remove REG_EQUIV notes on
3920 arguments too, as argument area is now clobbered by the call. */
3922 {
3925 }
3926 else
3927 {
3930 /* Ideally we'd emit a message for all of the ways that it could
3931 have failed. */
3933 }
3935 currently_expanding_call--;
3940 }
3942 /* A sibling call sequence invalidates any REG_EQUIV notes made for
3943 this function's incoming arguments.
3945 At the start of RTL generation we know the only REG_EQUIV notes
3946 in the rtl chain are those for incoming arguments, so we can look
3947 for REG_EQUIV notes between the start of the function and the
3948 NOTE_INSN_FUNCTION_BEG.
3950 This is (slight) overkill. We could keep track of the highest
3951 argument we clobber and be more selective in removing notes, but it
3952 does not seem to be worth the effort. */
3954 void
3956 {
3960 {
3961 rtx note;
3963 /* There are never REG_EQUIV notes for the incoming arguments
3964 after the NOTE_INSN_FUNCTION_BEG note, so stop if we see it. */
3974 }
3975 }
3977 /* Traverse a list of TYPES and expand all complex types into their
3978 components. */
3979 static tree
3981 {
3982 tree p;
3984 /* Before allocating memory, check for the common case of no complex. */
3986 {
3991 }
3994 found:
3998 {
4003 {
4006 /* Rewrite complex type with component type. */
4010 /* Add another component type for the imaginary part. */
4015 /* Skip the newly created node. */
4017 }
4018 }
4021 }
4022 \f
4023 /* Output a library call to function ORGFUN (a SYMBOL_REF rtx)
4024 for a value of mode OUTMODE,
4025 with NARGS different arguments, passed as ARGS.
4026 Store the return value if RETVAL is nonzero: store it in VALUE if
4027 VALUE is nonnull, otherwise pick a convenient location. In either
4028 case return the location of the stored value.
4030 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for
4031 `const' calls, LCT_PURE for `pure' calls, or another LCT_ value for
4032 other types of library calls. */
4034 rtx
4038 {
4039 /* Total size in bytes of all the stack-parms scanned so far. */
4041 /* Size of arguments before any adjustments (such as rounding). */
4044 rtx fun;
4045 /* Todo, choose the correct decl type of orgfun. Sadly this information
4046 isn't present here, so we default to native calling abi here. */
4051 CUMULATIVE_ARGS args_so_far_v;
4052 cumulative_args_t args_so_far;
4053 struct arg
4054 {
4055 rtx value;
4056 machine_mode mode;
4057 rtx reg;
4060 rtx save_area;
4061 };
4066 rtx valreg;
4071 poly_int64 needed;
4076 #ifdef REG_PARM_STACK_SPACE
4077 /* Define the boundary of the register parm stack space that needs to be
4078 save, if any. */
4081 #endif
4083 /* Size of the stack reserved for parameter registers. */
4091 #ifdef REG_PARM_STACK_SPACE
4093 #endif
4095 /* By default, library functions cannot throw. */
4099 {
4117 }
4120 /* Ensure current function's preferred stack boundary is at least
4121 what we need. */
4125 /* If this kind of value comes back in memory,
4126 decide where in memory it should come back. */
4128 {
4131 {
4132 #ifdef PCC_STATIC_STRUCT_RETURN
4133 rtx pointer_reg
4143 else
4145 #endif
4146 /* This call returns a big structure. */
4148 }
4149 }
4150 else
4153 /* ??? Unfinished: must pass the memory address as an argument. */
4155 /* Copy all the libcall-arguments out of the varargs data
4156 and into a vector ARGVEC.
4158 Compute how to pass each argument. We only support a very small subset
4159 of the full argument passing conventions to limit complexity here since
4160 library functions shouldn't have many args. */
4165 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
4167 #else
4169 #endif
4179 /* If there's a structure value address to be passed,
4180 either pass it in the special place, or pass it as an extra argument. */
4182 {
4185 nargs++;
4187 /* Make sure it is a reasonable operand for a move or push insn. */
4202 #ifdef STACK_PARMS_IN_REG_PARM_AREA
4204 #else
4206 #endif
4216 count++;
4217 }
4220 {
4225 /* We cannot convert the arg value to the mode the library wants here;
4226 must do it earlier where we know the signedness of the arg. */
4231 /* Make sure it is a reasonable operand for a move or push insn. */
4238 {
4239 rtx slot;
4242 /* If this was a CONST function, it is now PURE since it now
4243 reads memory. */
4245 {
4248 }
4251 {
4256 }
4257 else
4258 {
4262 }
4266 call_fusage);
4270 slot),
4271 call_fusage);
4276 }
4282 unsigned_p);
4291 {
4293 #ifdef STACK_PARMS_IN_REG_PARM_AREA
4295 #else
4297 #endif
4302 }
4303 #ifdef BLOCK_REG_PADDING
4304 else
4305 /* The argument is passed entirely in registers. See at which
4306 end it should be padded. */
4310 UNITS_PER_WORD));
4311 #endif
4314 }
4322 /* If this machine requires an external definition for library
4323 functions, write one out. */
4329 STACK_BYTES)
4333 reg_parm_stack_space);
4342 {
4344 current_function_pushed_stack_size
4346 }
4349 {
4350 /* Since the stack pointer will never be pushed, it is possible for
4351 the evaluation of a parm to clobber something we have already
4352 written to the stack. Since most function calls on RISC machines
4353 do not use the stack, this is uncommon, but must work correctly.
4355 Therefore, we save any area of the stack that was already written
4356 and that we are using. Here we set up to do this by making a new
4357 stack usage map from the old one.
4359 Another approach might be to try to reorder the argument
4360 evaluations to avoid this conflicting stack usage. */
4364 /* Since we will be writing into the entire argument area, the
4365 map must be allocated for its entire size, not just the part that
4366 is the responsibility of the caller. */
4374 /* For polynomial sizes, this is the maximum possible size needed
4375 for arguments with a constant size and offset. */
4378 const_limit);
4385 initial_highest_arg_in_use);
4392 /* We must be careful to use virtual regs before they're instantiated,
4393 and real regs afterwards. Loop optimization, for example, can create
4394 new libcalls after we've instantiated the virtual regs, and if we
4395 use virtuals anyway, they won't match the rtl patterns. */
4399 STACK_POINTER_OFFSET);
4400 else
4402 }
4403 else
4404 {
4407 }
4409 /* We push args individually in reverse order, perform stack alignment
4410 before the first push (the last arg). */
4414 Pmode));
4418 #ifdef REG_PARM_STACK_SPACE
4420 {
4421 /* The argument list is the property of the called routine and it
4422 may clobber it. If the fixed area has been used for previous
4423 parameters, we must save and restore it. */
4426 }
4427 #endif
4429 /* When expanding a normal call, args are stored in push order,
4430 which is the reverse of what we have here. */
4434 {
4437 }
4441 /* Push the args that need to be pushed. */
4445 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4446 are to be pushed. */
4448 {
4457 {
4458 rtx use;
4461 {
4462 /* If this is being stored into a pre-allocated, fixed-size,
4463 stack area, save any previous data at that location. */
4466 {
4467 /* stack_slot is negative, but we want to index stack_usage_map
4468 with positive values. */
4471 }
4472 else
4473 {
4476 }
4479 reg_parm_stack_space))
4480 {
4481 /* We need to make a save area. */
4482 poly_uint64 size
4484 machine_mode save_mode
4486 rtx adr
4489 rtx stack_area
4493 {
4497 );
4501 stack_area,
4502 (gen_int_mode
4504 Pmode)),
4505 BLOCK_OP_CALL_PARM);
4506 }
4507 else
4508 {
4512 }
4513 }
4514 }
4518 (gen_int_mode
4520 reg_parm_stack_space,
4523 /* Now mark the segment we just used. */
4527 NO_DEFER_POP;
4529 /* Indicate argument access so that alias.c knows that these
4530 values are live. */
4536 else
4537 {
4538 /* When arguments are pushed, trying to tell alias.c where
4539 exactly this argument is won't work, because the
4540 auto-increment causes confusion. So we merely indicate
4541 that we access something with a known mode somewhere on
4542 the stack. */
4546 }
4550 }
4551 }
4557 /* Now load any reg parms into their regs. */
4559 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4560 are to be pushed. */
4562 {
4568 /* Handle calls that pass values in multiple non-contiguous
4569 locations. The PA64 has examples of this for library calls. */
4573 {
4575 #ifdef BLOCK_REG_PADDING
4578 /* Copied from load_register_parameters. */
4580 /* Handle case where we have a value that needs shifting
4581 up to the msb. eg. a QImode value and we're padding
4582 upward on a BYTES_BIG_ENDIAN machine. */
4586 {
4587 rtx x;
4590 /* Assigning REG here rather than a temp makes CALL_FUSAGE
4591 report the whole reg as used. Strictly speaking, the
4592 call only uses SIZE bytes at the msb end, but it doesn't
4593 seem worth generating rtl to say that. */
4598 }
4599 #endif
4600 }
4602 NO_DEFER_POP;
4603 }
4605 /* Any regs containing parms remain in use through the call. */
4607 {
4612 {
4615 {
4620 }
4621 else
4623 }
4624 }
4626 /* Pass the function the address in which to return a structure value. */
4628 {
4632 NULL_RTX)));
4635 }
4637 /* Don't allow popping to be deferred, since then
4638 cse'ing of library calls could delete a call and leave the pop. */
4639 NO_DEFER_POP;
4643 /* Stack must be properly aligned now. */
4652 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4653 will set inhibit_defer_pop to that value. */
4654 /* The return type is needed to decide how many bytes the function pops.
4655 Signedness plays no role in that, so for simplicity, we pretend it's
4656 always signed. We also assume that the list of arguments passed has
4657 no impact, so we pretend it is unknown. */
4663 struct_value_size,
4666 valreg,
4670 {
4675 }
4677 /* Right-shift returned value if necessary. */
4681 {
4684 }
4688 /* For calls to `setjmp', etc., inform function.c:setjmp_warnings
4689 that it should complain if nonvolatile values are live. For
4690 functions that cannot return, inform flow that control does not
4691 fall through. */
4693 {
4694 /* The barrier note must be emitted
4695 immediately after the CALL_INSN. Some ports emit more than
4696 just a CALL_INSN above, so we must search for it here. */
4699 {
4701 /* There was no CALL_INSN? */
4703 }
4706 }
4708 /* Consider that "regular" libcalls, i.e. all of them except for LCT_THROW
4709 and LCT_RETURNS_TWICE, cannot perform non-local gotos. */
4711 {
4714 {
4716 /* There was no CALL_INSN? */
4718 }
4721 }
4723 /* Now restore inhibit_defer_pop to its actual original value. */
4724 OK_DEFER_POP;
4728 /* Copy the value to the right place. */
4730 {
4732 {
4737 }
4739 {
4743 }
4744 else
4745 {
4746 /* Convert to the proper mode if a promotion has been active. */
4748 {
4755 }
4759 else
4761 }
4762 }
4765 {
4766 #ifdef REG_PARM_STACK_SPACE
4770 #endif
4772 /* If we saved any argument areas, restore them. */
4775 {
4784 validize_mem
4786 (gen_int_mode
4788 BLOCK_OP_CALL_PARM);
4789 else
4791 }
4796 }
4802 }
4803 \f
4805 /* Store a single argument for a function call
4806 into the register or memory area where it must be passed.
4807 *ARG describes the argument value and where to pass it.
4809 ARGBLOCK is the address of the stack-block for all the arguments,
4810 or 0 on a machine where arguments are pushed individually.
4812 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4813 so must be careful about how the stack is used.
4815 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4816 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4817 that we need not worry about saving and restoring the stack.
4819 FNDECL is the declaration of the function we are calling.
4821 Return nonzero if this arg should cause sibcall failure,
4822 zero otherwise. */
4824 static int
4827 {
4838 /* Push a new temporary level for any temporaries we make for
4839 this argument. */
4843 {
4844 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4845 save any previous data at that location. */
4847 {
4849 {
4850 /* stack_slot is negative, but we want to index stack_usage_map
4851 with positive values. */
4853 {
4856 }
4857 else
4861 }
4862 else
4863 {
4865 {
4868 }
4869 else
4873 }
4876 reg_parm_stack_space))
4877 {
4878 /* We need to make a save area. */
4880 machine_mode save_mode
4886 {
4887 arg->save_area
4891 stack_area,
4892 (gen_int_mode
4894 BLOCK_OP_CALL_PARM);
4895 }
4896 else
4897 {
4900 }
4901 }
4902 }
4903 }
4905 /* If this isn't going to be placed on both the stack and in registers,
4906 set up the register and number of words. */
4908 {
4911 else
4914 }
4916 /* Being passed entirely in a register. We shouldn't be called in
4917 this case. */
4920 /* If this arg needs special alignment, don't load the registers
4921 here. */
4925 /* If this is being passed partially in a register, we can't evaluate
4926 it directly into its stack slot. Otherwise, we can. */
4928 {
4929 /* stack_arg_under_construction is nonzero if a function argument is
4930 being evaluated directly into the outgoing argument list and
4931 expand_call must take special action to preserve the argument list
4932 if it is called recursively.
4934 For scalar function arguments stack_usage_map is sufficient to
4935 determine which stack slots must be saved and restored. Scalar
4936 arguments in general have pass_on_stack == 0.
4938 If this argument is initialized by a function which takes the
4939 address of the argument (a C++ constructor or a C function
4940 returning a BLKmode structure), then stack_usage_map is
4941 insufficient and expand_call must push the stack around the
4942 function call. Such arguments have pass_on_stack == 1.
4944 Note that it is always safe to set stack_arg_under_construction,
4945 but this generates suboptimal code if set when not needed. */
4948 stack_arg_under_construction++;
4951 (partial
4956 /* If we are promoting object (or for any other reason) the mode
4957 doesn't agree, convert the mode. */
4964 stack_arg_under_construction--;
4965 }
4967 /* Check for overlap with already clobbered argument area. */
4974 /* Don't allow anything left on stack from computation
4975 of argument to alloca. */
4980 /* If the value is already in the stack slot, we are done. */
4981 ;
4983 {
4986 /* Argument is a scalar, not entirely passed in registers.
4987 (If part is passed in registers, arg->partial says how much
4988 and emit_push_insn will take care of putting it there.)
4990 Push it, and if its size is less than the
4991 amount of space allocated to it,
4992 also bump stack pointer by the additional space.
4993 Note that in C the default argument promotions
4994 will prevent such mismatches. */
4999 /* Compute how much space the push instruction will push.
5000 On many machines, pushing a byte will advance the stack
5001 pointer by a halfword. */
5002 #ifdef PUSH_ROUNDING
5004 #endif
5007 /* Compute how much space the argument should get:
5008 round up to a multiple of the alignment for arguments. */
5011 /* At the moment we don't (need to) support ABIs for which the
5012 padding isn't known at compile time. In principle it should
5013 be easy to add though. */
5016 /* Compute the alignment of the pushed argument. */
5020 {
5025 }
5027 /* This isn't already where we want it on the stack, so put it there.
5028 This can either be done with push or copy insns. */
5033 reg_parm_stack_space,
5037 /* Unless this is a partially-in-register argument, the argument is now
5038 in the stack. */
5041 }
5042 else
5043 {
5044 /* BLKmode, at least partly to be pushed. */
5047 poly_int64 excess;
5048 rtx size_rtx;
5050 /* Pushing a nonscalar.
5051 If part is passed in registers, PARTIAL says how much
5052 and emit_push_insn will take care of putting it there. */
5054 /* Round its size up to a multiple
5055 of the allocation unit for arguments. */
5058 {
5061 }
5062 else
5063 {
5064 /* PUSH_ROUNDING has no effect on us, because emit_push_insn
5065 for BLKmode is careful to avoid it. */
5071 EXPAND_NORMAL);
5072 }
5076 /* When an argument is padded down, the block is aligned to
5077 PARM_BOUNDARY, but the actual argument isn't. */
5080 {
5083 else
5084 {
5085 unsigned int excess_align
5089 }
5090 }
5093 {
5094 /* emit_push_insn might not work properly if arg->value and
5095 argblock + arg->locate.offset areas overlap. */
5101 {
5102 /* arg.locate doesn't contain the pretend_args_size offset,
5103 it's part of argblock. Ensure we don't count it in I. */
5106 else
5109 /* expand_call should ensure this. */
5115 {
5116 /* Even though they appear to be at the same location,
5117 if part of the outgoing argument is in registers,
5118 they aren't really at the same location. Check for
5119 this by making sure that the incoming size is the
5120 same as the outgoing size. */
5123 }
5127 /* Use arg->locate.size.constant instead of size_rtx
5128 because we only care about the part of the argument
5129 on the stack. */
5133 }
5134 }
5140 reg_parm_stack_space,
5143 /* Unless this is a partially-in-register argument, the argument is now
5144 in the stack.
5146 ??? Unlike the case above, in which we want the actual
5147 address of the data, so that we can load it directly into a
5148 register, here we want the address of the stack slot, so that
5149 it's properly aligned for word-by-word copying or something
5150 like that. It's not clear that this is always correct. */
5153 }
5156 {
5158 arg->parallel_value
5161 }
5163 /* Mark all slots this store used. */
5168 /* Once we have pushed something, pops can't safely
5169 be deferred during the rest of the arguments. */
5170 NO_DEFER_POP;
5172 /* Free any temporary slots made in processing this argument. */
5176 }
5178 /* Nonzero if we do not know how to pass ARG solely in registers. */
5180 bool
5182 {
5186 /* If the type has variable size... */
5190 /* If the type is marked as addressable (it is required
5191 to be constructed into the stack)... */
5196 }
5198 /* Another version of the TARGET_MUST_PASS_IN_STACK hook. This one
5199 takes trailing padding of a structure into account. */
5200 /* ??? Should be able to merge these two by examining BLOCK_REG_PADDING. */
5202 bool
5204 {
5208 /* If the type has variable size... */
5212 /* If the type is marked as addressable (it is required
5213 to be constructed into the stack)... */
5220 /* If the padding and mode of the type is such that a copy into
5221 a register would put it into the wrong part of the register. */
5229 }
5231 /* Return true if TYPE must be passed on the stack when passed to
5232 the "..." arguments of a function. */
5234 bool
5236 {
5239 }
5241 /* Return true if FIELD is the C++17 empty base field that should
5242 be ignored for ABI calling convention decisions in order to
5243 maintain ABI compatibility between C++14 and earlier, which doesn't
5244 add this FIELD to classes with empty bases, and C++17 and later
5245 which does. */
5247 bool
5249 {
5254 }