| blob | 4d0bc45be280f3936928f93e4b0dc761b421efdf |
1 /* Convert function calls to rtl insns, for GNU C compiler.
2 Copyright (C) 1989-2022 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 {
208 else
210 }
212 /* Force FUNEXP into a form suitable for the address of a CALL,
213 and return that as an rtx. Also load the static chain register
214 if FNDECL is a nested function.
216 CALL_FUSAGE points to a variable holding the prospective
217 CALL_INSN_FUNCTION_USAGE information. */
219 rtx
222 {
223 /* Make a valid memory address and copy constants through pseudo-regs,
224 but not for a constant address if -fno-function-cse. */
226 {
227 /* If it's an indirect call by descriptor, generate code to perform
228 runtime identification of the pointer and load the descriptor. */
230 {
235 fndecl_or_type
237 fndecl_or_type);
244 /* Avoid long live ranges around function calls. */
250 /* Emit the runtime identification pattern. */
253 call_lab);
255 /* Statically predict the branch to very likely taken. */
260 /* Load the descriptor. */
269 POINTER_SIZE / BITS_PER_UNIT
278 {
281 }
283 /* Make sure we're not going to be overwritten below. */
285 }
287 /* If we are using registers for parameters, force the
288 function address into a register now. */
289 funexp = ((reg_parm_seen
293 }
294 else
295 {
296 /* funexp could be a SYMBOL_REF represents a function pointer which is
297 of ptr_mode. In this case, it should be converted into address mode
298 to be a valid address for memory rtx pattern. See PR 64971. */
303 {
306 }
307 }
312 {
313 rtx chain;
320 {
323 }
324 }
327 }
329 /* Generate instructions to call function FUNEXP,
330 and optionally pop the results.
331 The CALL_INSN is the first insn generated.
333 FNDECL is the declaration node of the function. This is given to the
334 hook TARGET_RETURN_POPS_ARGS to determine whether this function pops
335 its own args.
337 FUNTYPE is the data type of the function. This is given to the hook
338 TARGET_RETURN_POPS_ARGS to determine whether this function pops its
339 own args. We used to allow an identifier for library functions, but
340 that doesn't work when the return type is an aggregate type and the
341 calling convention says that the pointer to this aggregate is to be
342 popped by the callee.
344 STACK_SIZE is the number of bytes of arguments on the stack,
345 ROUNDED_STACK_SIZE is that number rounded up to
346 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
347 both to put into the call insn and to generate explicit popping
348 code if necessary.
350 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
351 It is zero if this call doesn't want a structure value.
353 NEXT_ARG_REG is the rtx that results from executing
354 targetm.calls.function_arg (&args_so_far,
355 function_arg_info::end_marker ());
356 just after all the args have had their registers assigned.
357 This could be whatever you like, but normally it is the first
358 arg-register beyond those used for args in this call,
359 or 0 if all the arg-registers are used in this call.
360 It is passed on to `gen_call' so you can put this info in the call insn.
362 VALREG is a hard register in which a value is returned,
363 or 0 if the call does not return a value.
365 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
366 the args to this call were processed.
367 We restore `inhibit_defer_pop' to that value.
369 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
370 denote registers used by the called function. */
372 static void
374 tree funtype ATTRIBUTE_UNUSED,
375 poly_int64 stack_size ATTRIBUTE_UNUSED,
376 poly_int64 rounded_stack_size,
377 poly_int64 struct_value_size ATTRIBUTE_UNUSED,
380 cumulative_args_t args_so_far ATTRIBUTE_UNUSED)
381 {
387 /* Sibling call patterns never pop arguments (no sibcall(_value)_pop
388 patterns exist). Any popping that the callee does on return will
389 be from our caller's frame rather than ours. */
391 {
394 #ifdef CALL_POPS_ARGS
396 #endif
397 }
399 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
400 and we don't want to load it into a register as an optimization,
401 because prepare_call_address already did it if it should be done. */
407 {
410 /* Although a built-in FUNCTION_DECL and its non-__builtin
411 counterpart compare equal and get a shared mem_attrs, they
412 produce different dump output in compare-debug compilations,
413 if an entry gets garbage collected in one compilation, then
414 adds a different (but equivalent) entry, while the other
415 doesn't run the garbage collector at the same spot and then
416 shares the mem_attr with the equivalent entry. */
418 {
422 }
425 }
430 {
433 rounded_stack_size_rtx,
435 else
437 next_arg_reg,
439 }
440 /* If the target has "call" or "call_value" insns, then prefer them
441 if no arguments are actually popped. If the target does not have
442 "call" or "call_value" insns, then we must use the popping versions
443 even if the call has no arguments to pop. */
445 || !(valreg
448 {
451 /* If this subroutine pops its own args, record that in the call insn
452 if possible, for the sake of frame pointer elimination. */
456 rounded_stack_size_rtx,
458 else
463 }
464 else
465 {
469 else
472 }
475 /* Find the call we just emitted. */
478 /* Some target create a fresh MEM instead of reusing the one provided
479 above. Set its MEM_EXPR. */
486 /* Put the register usage information there. */
489 /* If this is a const call, then set the insn's unchanging bit. */
493 /* If this is a pure call, then set the insn's unchanging bit. */
497 /* If this is a const call, then set the insn's unchanging bit. */
501 /* Create a nothrow REG_EH_REGION note, if needed. */
508 {
511 }
515 /* Restore this now, so that we do defer pops for this call's args
516 if the context of the call as a whole permits. */
520 {
532 /* If popup is needed, stack realign must use DRAP */
535 }
536 /* For noreturn calls when not accumulating outgoing args force
537 REG_ARGS_SIZE note to prevent crossjumping of calls with different
538 args sizes. */
543 {
544 /* If returning from the subroutine does not automatically pop the args,
545 we need an instruction to pop them sooner or later.
546 Perhaps do it now; perhaps just record how much space to pop later.
548 If returning from the subroutine does pop the args, indicate that the
549 stack pointer will be changed. */
552 {
554 /* Just pretend we did the pop. */
559 else
561 }
562 }
563 /* When we accumulate outgoing args, we must avoid any stack manipulations.
564 Restore the stack pointer to its original value now. Usually
565 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
566 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
567 popping variants of functions exist as well.
569 ??? We may optimize similar to defer_pop above, but it is
570 probably not worthwhile.
572 ??? It will be worthwhile to enable combine_stack_adjustments even for
573 such machines. */
576 }
578 /* Determine if the function identified by FNDECL is one with
579 special properties we wish to know about. Modify FLAGS accordingly.
581 For example, if the function might return more than one time (setjmp), then
582 set ECF_RETURNS_TWICE.
584 Set ECF_MAY_BE_ALLOCA for any memory allocation function that might allocate
585 space from the stack such as alloca. */
587 static int
589 {
594 {
598 /* We assume that alloca will always be called by name. It
599 makes no sense to pass it as a pointer-to-function to
600 anything that does not understand its behavior. */
606 /* Disregard prefix _ or __. */
608 {
611 else
613 }
615 /* ECF_RETURNS_TWICE is safe even for -ffreestanding. */
622 }
629 }
631 /* Return fnspec for DECL. */
633 static attr_fnspec
635 {
636 tree attr;
639 {
642 {
644 }
645 }
649 }
651 /* Similar to special_function_p; return a set of ERF_ flags for the
652 function FNDECL. */
653 static int
655 {
665 }
667 /* Return nonzero when FNDECL represents a call to setjmp. */
669 int
671 {
675 }
678 /* Return true if STMT may be an alloca call. */
680 bool
682 {
683 tree fndecl;
693 }
695 /* Return true if STMT is a builtin alloca call. */
697 bool
699 {
700 tree fndecl;
708 {
709 CASE_BUILT_IN_ALLOCA:
713 }
716 }
718 /* Return true when exp contains a builtin alloca call. */
720 bool
722 {
723 tree fndecl;
728 {
729 CASE_BUILT_IN_ALLOCA:
733 }
736 }
738 /* Return TRUE if FNDECL is either a TM builtin or a TM cloned
739 function. Return FALSE otherwise. */
741 static bool
743 {
751 {
753 {
796 }
797 }
799 }
801 /* Detect flags (function attributes) from the function decl or type node. */
803 int
805 {
809 {
810 /* The function exp may have the `malloc' attribute. */
814 /* The function exp may have the `returns_twice' attribute. */
818 /* Process the pure and const attributes. */
837 {
844 }
847 }
849 {
857 }
858 else
862 {
866 }
869 }
871 /* Detect flags from a CALL_EXPR. */
873 int
875 {
883 else
884 {
888 else
892 }
895 }
897 /* Return true if ARG should be passed by invisible reference. */
899 bool
901 {
903 {
904 /* If this type contains non-trivial constructors, then it is
905 forbidden for the middle-end to create any new copies. */
909 /* GCC post 3.4 passes *all* variable sized types by reference. */
913 /* If a record type should be passed the same as its first (and only)
914 member, use the type and mode of that member. */
916 {
919 }
920 }
923 }
925 /* Return true if TYPE should be passed by reference when passed to
926 the "..." arguments of a function. */
928 bool
930 {
932 }
934 /* Decide whether ARG, which occurs in the state described by CA,
935 should be passed by reference. Return true if so and update
936 ARG accordingly. */
938 bool
940 {
942 {
947 }
949 }
951 /* Return true if ARG, which is passed by reference, should be callee
952 copied instead of caller copied. */
954 bool
956 {
960 }
963 /* Precompute all register parameters as described by ARGS, storing values
964 into fields within the ARGS array.
966 NUM_ACTUALS indicates the total number elements in the ARGS array.
968 Set REG_PARM_SEEN if we encounter a register parameter. */
970 static void
973 {
980 {
984 {
989 }
991 /* If we are to promote the function arg to a wider mode,
992 do it now. */
1000 /* If the value is a non-legitimate constant, force it into a
1001 pseudo now. TLS symbols sometimes need a call to resolve. */
1007 /* If we're going to have to load the value by parts, pull the
1008 parts into pseudos. The part extraction process can involve
1009 non-trivial computation. */
1011 {
1016 }
1018 /* If the value is expensive, and we are inside an appropriately
1019 short loop, put the value into a pseudo and then put the pseudo
1020 into the hard reg.
1022 For small register classes, also do this if this call uses
1023 register parameters. This is to avoid reload conflicts while
1024 loading the parameters registers. */
1033 && ((*reg_parm_seen
1037 }
1038 }
1040 #ifdef REG_PARM_STACK_SPACE
1042 /* The argument list is the property of the called routine and it
1043 may clobber it. If the fixed area has been used for previous
1044 parameters, we must save and restore it. */
1046 static rtx
1047 save_fixed_argument_area (int reg_parm_stack_space, rtx argblock, int *low_to_save, int *high_to_save)
1048 {
1052 /* Compute the boundary of the area that needs to be saved, if any. */
1062 {
1064 machine_mode save_mode;
1066 rtx addr;
1067 rtx stack_area;
1068 rtx save_area;
1071 ;
1078 /* If we don't have the required alignment, must do this
1079 in BLKmode. */
1080 scalar_int_mode imode;
1085 else
1090 else
1098 {
1102 }
1103 else
1104 {
1107 }
1110 }
1113 }
1115 static void
1117 {
1124 else
1133 else
1136 BLOCK_OP_CALL_PARM);
1137 }
1140 /* If any elements in ARGS refer to parameters that are to be passed in
1141 registers, but not in memory, and whose alignment does not permit a
1142 direct copy into registers. Copy the values into a group of pseudos
1143 which we will later copy into the appropriate hard registers.
1145 Pseudos for each unaligned argument will be stored into the array
1146 args[argnum].aligned_regs. The caller is responsible for deallocating
1147 the aligned_regs array if it is nonzero. */
1149 static void
1151 {
1161 {
1166 {
1169 }
1170 else
1171 {
1174 }
1178 /* Structures smaller than a word are normally aligned to the
1179 least significant byte. On a BYTES_BIG_ENDIAN machine,
1180 this means we must skip the empty high order bytes when
1181 calculating the bit offset. */
1183 #ifdef BLOCK_REG_PADDING
1187 #else
1188 && BYTES_BIG_ENDIAN
1189 #endif
1190 )
1194 {
1203 /* There is no need to restrict this code to loading items
1204 in TYPE_ALIGN sized hunks. The bitfield instructions can
1205 load up entire word sized registers efficiently.
1207 ??? This may not be needed anymore.
1208 We use to emit a clobber here but that doesn't let later
1209 passes optimize the instructions we emit. By storing 0 into
1210 the register later passes know the first AND to zero out the
1211 bitfield being set in the register is unnecessary. The store
1212 of 0 will be deleted as will at least the first AND. */
1219 }
1220 }
1221 }
1223 /* Issue an error if CALL_EXPR was flagged as requiring
1224 tall-call optimization. */
1226 void
1228 {
1234 }
1236 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
1237 CALL_EXPR EXP.
1239 NUM_ACTUALS is the total number of parameters.
1241 N_NAMED_ARGS is the total number of named arguments.
1243 STRUCT_VALUE_ADDR_VALUE is the implicit argument for a struct return
1244 value, or null.
1246 FNDECL is the tree code for the target of this call (if known)
1248 ARGS_SO_FAR holds state needed by the target to know where to place
1249 the next argument.
1251 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
1252 for arguments which are passed in registers.
1254 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
1255 and may be modified by this routine.
1257 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
1258 flags which may be modified by this routine.
1260 MAY_TAILCALL is cleared if we encounter an invisible pass-by-reference
1261 that requires allocation of stack space.
1263 CALL_FROM_THUNK_P is true if this call is the jump from a thunk to
1264 the thunked-to function. */
1266 static void
1273 cumulative_args_t args_so_far,
1279 {
1283 /* Count arg position in order args appear. */
1291 /* In this loop, we consider args in the order they are written.
1292 We fill up ARGS from the back. */
1295 {
1297 call_expr_arg_iterator iter;
1298 tree arg;
1301 {
1303 j--;
1304 }
1307 {
1311 && argtype
1314 {
1317 j--;
1319 }
1320 else
1322 j--;
1323 argpos++;
1324 }
1325 }
1327 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
1329 {
1333 /* Replace erroneous argument with constant zero. */
1337 /* If TYPE is a transparent union or record, pass things the way
1338 we would pass the first field of the union or record. We have
1339 already verified that the modes are the same. */
1343 /* Decide where to pass this arg.
1345 args[i].reg is nonzero if all or part is passed in registers.
1347 args[i].partial is nonzero if part but not all is passed in registers,
1348 and the exact value says how many bytes are passed in registers.
1350 args[i].pass_on_stack is nonzero if the argument must at least be
1351 computed on the stack. It may then be loaded back into registers
1352 if args[i].reg is nonzero.
1354 These decisions are driven by the FUNCTION_... macros and must agree
1355 with those made by function.cc. */
1357 /* See if this argument should be passed by invisible reference. */
1360 {
1361 const bool callee_copies
1363 tree base;
1365 /* If we're compiling a thunk, pass directly the address of an object
1366 already in memory, instead of making a copy. Likewise if we want
1367 to make the copy in the callee instead of the caller. */
1373 {
1374 /* We may have turned the parameter value into an SSA name.
1375 Go back to the original parameter so we can take the
1376 address. */
1378 {
1382 }
1383 /* Argument setup code may have copied the value to register. We
1384 revert that optimization now because the tail call code must
1385 use the original location. */
1395 /* We can't use sibcalls if a callee-copied argument is
1396 stored in the current function's frame. */
1398 {
1401 "a callee-copied argument is"
1402 " stored in the current"
1404 }
1412 }
1413 else
1414 {
1415 /* We make a copy of the object and pass the address to the
1416 function being called. */
1417 rtx copy;
1424 {
1425 /* This is a variable-sized object. Make space on the stack
1426 for it. */
1430 {
1434 }
1436 /* We can pass TRUE as the 4th argument because we just
1437 saved the stack pointer and will restore it right after
1438 the call. */
1442 max_int_size_in_bytes
1447 }
1448 else
1453 /* Just change the const function to pure and then let
1454 the next test clear the pure based on
1455 callee_copies. */
1457 {
1460 }
1470 "argument must be passed"
1472 }
1474 }
1478 arg.mode
1489 /* If this is a sibling call and the machine has register windows, the
1490 register window has to be unwinded before calling the routine, so
1491 arguments have to go into the incoming registers. */
1495 else
1503 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
1504 it means that we are to pass this arg in the register(s) designated
1505 by the PARALLEL, but also to pass it in the stack. */
1510 /* If this is an addressable type, we must preallocate the stack
1511 since we must evaluate the object into its final location.
1513 If this is to be passed in both registers and the stack, it is simpler
1514 to preallocate. */
1519 /* Compute the stack-size of this argument. */
1524 #ifdef STACK_PARMS_IN_REG_PARM_AREA
1526 #else
1528 #endif
1529 reg_parm_stack_space,
1532 #ifdef BLOCK_REG_PADDING
1533 else
1534 /* The argument is passed entirely in registers. See at which
1535 end it should be padded. */
1539 #endif
1541 /* Update ARGS_SIZE, the total stack space for args so far. */
1547 /* Increment ARGS_SO_FAR, which has info about which arg-registers
1548 have been used, etc. */
1550 /* ??? Traditionally we've passed TYPE_MODE here, instead of the
1551 promoted_mode used for function_arg above. However, the
1552 corresponding handling of incoming arguments in function.cc
1553 does pass the promoted mode. */
1556 }
1557 }
1559 /* Update ARGS_SIZE to contain the total size for the argument block.
1560 Return the original constant component of the argument block's size.
1562 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
1563 for arguments passed in registers. */
1565 static poly_int64
1568 tree fndecl ATTRIBUTE_UNUSED,
1569 tree fntype ATTRIBUTE_UNUSED,
1571 {
1574 /* For accumulate outgoing args mode we don't need to align, since the frame
1575 will be already aligned. Align to STACK_BOUNDARY in order to prevent
1576 backends from generating misaligned frame sizes. */
1580 /* Compute the actual size of the argument block required. The variable
1581 and constant sizes must be combined, the size may have to be rounded,
1582 and there may be a minimum required size. */
1585 {
1591 {
1592 /* We don't handle this case yet. To handle it correctly we have
1593 to add the delta, round and subtract the delta.
1594 Currently no machine description requires this support. */
1596 preferred_stack_boundary));
1598 }
1601 {
1602 args_size->var
1606 /* The area corresponding to register parameters is not to count in
1607 the size of the block we need. So make the adjustment. */
1609 args_size->var
1612 }
1613 }
1614 else
1615 {
1621 preferred_stack_boundary)
1625 reg_parm_stack_space);
1629 }
1631 }
1633 /* Precompute parameters as needed for a function call.
1635 FLAGS is mask of ECF_* constants.
1637 NUM_ACTUALS is the number of arguments.
1639 ARGS is an array containing information for each argument; this
1640 routine fills in the INITIAL_VALUE and VALUE fields for each
1641 precomputed argument. */
1643 static void
1645 {
1648 /* If this is a libcall, then precompute all arguments so that we do not
1649 get extraneous instructions emitted as part of the libcall sequence. */
1651 /* If we preallocated the stack space, and some arguments must be passed
1652 on the stack, then we must precompute any parameter which contains a
1653 function call which will store arguments on the stack.
1654 Otherwise, evaluating the parameter may clobber previous parameters
1655 which have already been stored into the stack. (we have code to avoid
1656 such case by saving the outgoing stack arguments, but it results in
1657 worse code) */
1662 {
1663 tree type;
1664 machine_mode mode;
1669 /* If this is an addressable type, we cannot pre-evaluate it. */
1678 {
1684 /* CSE will replace this only if it contains args[i].value
1685 pseudo, so convert it down to the declared mode using
1686 a SUBREG. */
1690 {
1695 }
1696 }
1697 }
1698 }
1700 /* Given the current state of MUST_PREALLOCATE and information about
1701 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
1702 compute and return the final value for MUST_PREALLOCATE. */
1704 static int
1707 {
1708 /* See if we have or want to preallocate stack space.
1710 If we would have to push a partially-in-regs parm
1711 before other stack parms, preallocate stack space instead.
1713 If the size of some parm is not a multiple of the required stack
1714 alignment, we must preallocate.
1716 If the total size of arguments that would otherwise create a copy in
1717 a temporary (such as a CALL) is more than half the total argument list
1718 size, preallocation is faster.
1720 Another reason to preallocate is if we have a machine (like the m88k)
1721 where stack alignment is required to be maintained between every
1722 pair of insns, not just when the call is made. However, we assume here
1723 that such machines either do not have push insns (and hence preallocation
1724 would occur anyway) or the problem is taken care of with
1725 PUSH_ROUNDING. */
1728 {
1734 {
1745 copy_to_evaluate_size
1747 }
1752 }
1754 }
1756 /* If we preallocated stack space, compute the address of each argument
1757 and store it into the ARGS array.
1759 We need not ensure it is a valid memory address here; it will be
1760 validized when it is used.
1762 ARGBLOCK is an rtx for the address of the outgoing arguments. */
1764 static void
1766 {
1768 {
1774 {
1777 }
1780 {
1783 rtx addr;
1788 /* Skip this parm if it will not be passed on the stack. */
1801 {
1802 /* Only part of the parameter is being passed on the stack.
1803 Generate a simple memory reference of the correct size. */
1809 }
1810 else
1811 {
1815 }
1818 poly_int64 offset_val;
1822 {
1824 unsigned int offset_align
1828 }
1835 {
1836 /* Only part of the parameter is being passed on the stack.
1837 Generate a simple memory reference of the correct size.
1838 */
1841 }
1842 else
1843 {
1847 }
1850 /* Function incoming arguments may overlap with sibling call
1851 outgoing arguments and we cannot allow reordering of reads
1852 from function arguments with stores to outgoing arguments
1853 of sibling calls. */
1856 }
1857 }
1858 }
1860 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
1861 in a call instruction.
1863 FNDECL is the tree node for the target function. For an indirect call
1864 FNDECL will be NULL_TREE.
1866 ADDR is the operand 0 of CALL_EXPR for this call. */
1868 static rtx
1870 {
1871 rtx funexp;
1873 /* Get the function to call, in the form of RTL. */
1875 {
1879 /* Get a SYMBOL_REF rtx for the function address. */
1881 }
1882 else
1883 /* Generate an rtx (probably a pseudo-register) for the address. */
1884 {
1888 }
1890 }
1892 /* Return the static chain for this function, if any. */
1894 rtx
1896 {
1901 }
1903 /* Internal state for internal_arg_pointer_based_exp and its helpers. */
1904 static struct
1905 {
1906 /* Last insn that has been scanned by internal_arg_pointer_based_exp_scan,
1907 or NULL_RTX if none has been scanned yet. */
1909 /* Vector indexed by REGNO - FIRST_PSEUDO_REGISTER, recording if a pseudo is
1910 based on crtl->args.internal_arg_pointer. The element is NULL_RTX if the
1911 pseudo isn't based on it, a CONST_INT offset if the pseudo is based on it
1912 with fixed offset, or PC if this is with variable or unknown offset. */
1918 /* Helper function for internal_arg_pointer_based_exp. Scan insns in
1919 the tail call sequence, starting with first insn that hasn't been
1920 scanned yet, and note for each pseudo on the LHS whether it is based
1921 on crtl->args.internal_arg_pointer or not, and what offset from that
1922 that pointer it has. */
1924 static void
1926 {
1931 else
1935 {
1938 {
1941 /* Punt on pseudos set multiple times. */
1946 else
1949 {
1951 internal_arg_pointer_exp_state.cache
1954 }
1955 }
1959 }
1962 }
1964 /* Compute whether RTL is based on crtl->args.internal_arg_pointer. Return
1965 NULL_RTX if RTL isn't based on it, a CONST_INT offset if RTL is based on
1966 it with fixed offset, or PC if this is with variable or unknown offset.
1967 TOPLEVEL is true if the function is invoked at the topmost level. */
1969 static rtx
1971 {
1981 poly_int64 offset;
1983 {
1988 }
1990 /* When called at the topmost level, scan pseudo assignments in between the
1991 last scanned instruction in the tail call sequence and the latest insn
1992 in that sequence. */
1997 {
2003 }
2007 {
2013 }
2016 }
2018 /* Return true if SIZE bytes starting from address ADDR might overlap an
2019 already-clobbered argument area. This function is used to determine
2020 if we should give up a sibcall. */
2022 static bool
2024 {
2025 poly_int64 i;
2027 rtx val;
2043 else
2049 /* We can ignore any references to the function's pretend args,
2050 which at this point would manifest as negative values of I. */
2067 }
2069 /* Do the register loads required for any wholly-register parms or any
2070 parms which are passed both on the stack and in a register. Their
2071 expressions were already evaluated.
2073 Mark all register-parms as living through the call, putting these USE
2074 insns in the CALL_INSN_FUNCTION_USAGE field.
2076 When IS_SIBCALL, perform the check_sibcall_argument_overlap
2077 checking, setting *SIBCALL_FAILURE if appropriate. */
2079 static void
2083 {
2087 {
2091 {
2100 /* Set non-negative if we must move a word at a time, even if
2101 just one word (e.g, partial == 4 && mode == DFmode). Set
2102 to -1 if we just use a normal move insn. This value can be
2103 zero if the argument is a zero size structure. */
2106 ;
2108 {
2111 }
2113 {
2114 /* Variable-sized parameters should be described by a
2115 PARALLEL instead. */
2120 }
2121 else
2124 /* Handle calls that pass values in multiple non-contiguous
2125 locations. The Irix 6 ABI has examples of this. */
2130 /* If simple case, just do move. If normal partial, store_one_arg
2131 has already loaded the register for us. In all other cases,
2132 load the register(s) from memory. */
2135 {
2137 #ifdef BLOCK_REG_PADDING
2138 /* Handle case where we have a value that needs shifting
2139 up to the msb. eg. a QImode value and we're padding
2140 upward on a BYTES_BIG_ENDIAN machine. */
2143 {
2146 {
2147 rtx x;
2148 poly_int64 shift
2151 /* Assigning REG here rather than a temp makes
2152 CALL_FUSAGE report the whole reg as used.
2153 Strictly speaking, the call only uses SIZE
2154 bytes at the msb end, but it doesn't seem worth
2155 generating rtl to say that. */
2161 }
2162 }
2163 #endif
2164 }
2166 /* If we have pre-computed the values to put in the registers in
2167 the case of non-aligned structures, copy them in now. */
2175 {
2176 /* SIZE and CONST_SIZE are 0 for partial arguments and
2177 the size of a BLKmode type otherwise. */
2181 /* Check for overlap with already clobbered argument area,
2182 providing that this has non-zero size. */
2185 && (mem_might_overlap_already_clobbered_arg_p
2192 else
2193 {
2202 NULL);
2208 }
2210 /* Handle a BLKmode that needs shifting. */
2212 #ifdef BLOCK_REG_PADDING
2214 #else
2215 && BYTES_BIG_ENDIAN
2216 #endif
2217 )
2218 {
2223 rtx x;
2228 }
2229 }
2231 /* When a parameter is a block, and perhaps in other cases, it is
2232 possible that it did a load from an argument slot that was
2233 already clobbered. */
2238 /* Handle calls that pass values in multiple non-contiguous
2239 locations. The Irix 6 ABI has examples of this. */
2246 }
2247 }
2248 }
2250 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
2251 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
2252 bytes, then we would need to push some additional bytes to pad the
2253 arguments. So, we try to compute an adjust to the stack pointer for an
2254 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
2255 bytes. Then, when the arguments are pushed the stack will be perfectly
2256 aligned.
2258 Return true if this optimization is possible, storing the adjustment
2259 in ADJUSTMENT_OUT and setting ARGS_SIZE->CONSTANT to the number of
2260 bytes that should be popped after the call. */
2262 static bool
2264 poly_int64 unadjusted_args_size,
2267 {
2268 /* The number of bytes to pop so that the stack will be
2269 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
2270 poly_int64 adjustment;
2271 /* The alignment of the stack after the arguments are pushed, if we
2272 just pushed the arguments without adjust the stack here. */
2276 preferred_unit_stack_boundary,
2280 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
2281 as possible -- leaving just enough left to cancel out the
2282 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
2283 PENDING_STACK_ADJUST is non-negative, and congruent to
2284 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
2286 /* Begin by trying to pop all the bytes. */
2289 preferred_unit_stack_boundary,
2294 /* Push enough additional bytes that the stack will be aligned
2295 after the arguments are pushed. */
2299 /* We need to know whether the adjusted argument size
2300 (UNADJUSTED_ARGS_SIZE - ADJUSTMENT) constitutes an allocation
2301 or a deallocation. */
2305 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
2306 bytes after the call. The right number is the entire
2307 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
2308 by the arguments in the first place. */
2309 args_size->constant
2314 }
2316 /* Scan X expression if it does not dereference any argument slots
2317 we already clobbered by tail call arguments (as noted in stored_args_map
2318 bitmap).
2319 Return nonzero if X expression dereferences such argument slots,
2320 zero otherwise. */
2322 static int
2324 {
2325 RTX_CODE code;
2334 /* We need not check the operands of the CALL expression itself. */
2342 /* Scan all subexpressions. */
2345 {
2347 {
2350 }
2352 {
2356 }
2357 }
2359 }
2361 /* Scan sequence after INSN if it does not dereference any argument slots
2362 we already clobbered by tail call arguments (as noted in stored_args_map
2363 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
2364 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
2365 should be 0). Return nonzero if sequence after INSN dereferences such argument
2366 slots, zero otherwise. */
2368 static int
2371 {
2377 else
2386 {
2389 else
2397 else
2399 }
2401 }
2403 /* Given that a function returns a value of mode MODE at the most
2404 significant end of hard register VALUE, shift VALUE left or right
2405 as specified by LEFT_P. Return true if some action was needed. */
2407 bool
2409 {
2417 /* Use ashr rather than lshr for right shifts. This is for the benefit
2418 of the MIPS port, which requires SImode values to be sign-extended
2419 when stored in 64-bit registers. */
2425 }
2427 /* If X is a likely-spilled register value, copy it to a pseudo
2428 register and return that register. Return X otherwise. */
2430 static rtx
2432 {
2433 rtx new_rtx;
2438 {
2439 /* Make sure that we generate a REG rather than a CONCAT.
2440 Moves into CONCATs can need nontrivial instructions,
2441 and the whole point of this function is to avoid
2442 using the hard register directly in such a situation. */
2448 }
2450 }
2452 /* Helper function for expand_call.
2453 Return false is EXP is not implementable as a sibling call. */
2455 static bool
2457 rtx structure_value_addr,
2458 tree funtype,
2459 tree fndecl,
2461 tree addr,
2463 {
2465 {
2466 maybe_complain_about_tail_call
2468 "machine description does not have"
2471 }
2473 /* Doing sibling call optimization needs some work, since
2474 structure_value_addr can be allocated on the stack.
2475 It does not seem worth the effort since few optimizable
2476 sibling calls will return a structure. */
2478 {
2481 }
2483 /* Check whether the target is able to optimize the call
2484 into a sibcall. */
2486 {
2488 "target is not able to optimize the"
2491 }
2493 /* Functions that do not return exactly once may not be sibcall
2494 optimized. */
2496 {
2499 }
2501 {
2504 }
2507 {
2510 }
2512 /* If the called function is nested in the current one, it might access
2513 some of the caller's arguments, but could clobber them beforehand if
2514 the argument areas are shared. */
2516 {
2519 }
2521 /* If this function requires more stack slots than the current
2522 function, we cannot change it into a sibling call.
2523 crtl->args.pretend_args_size is not part of the
2524 stack allocated by our caller. */
2527 {
2529 "callee required more stack slots"
2532 }
2534 /* If the callee pops its own arguments, then it must pop exactly
2535 the same number of arguments as the current function. */
2539 TREE_TYPE
2542 {
2544 "inconsistent number of"
2547 }
2550 {
2554 }
2556 /* All checks passed. */
2558 }
2560 /* Update stack alignment when the parameter is passed in the stack
2561 since the outgoing parameter requires extra alignment on the calling
2562 function side. */
2564 static void
2566 {
2571 }
2573 /* Generate all the code for a CALL_EXPR exp
2574 and return an rtx for its value.
2575 Store the value in TARGET (specified as an rtx) if convenient.
2576 If the value is stored in TARGET then TARGET is returned.
2577 If IGNORE is nonzero, then we ignore the value of the function call. */
2579 rtx
2581 {
2582 /* Nonzero if we are currently expanding a call. */
2585 /* RTX for the function to be called. */
2586 rtx funexp;
2587 /* Sequence of insns to perform a normal "call". */
2589 /* Sequence of insns to perform a tail "call". */
2591 /* Data type of the function. */
2592 tree funtype;
2593 tree type_arg_types;
2594 tree rettype;
2595 /* Declaration of the function being called,
2596 or 0 if the function is computed (not known by name). */
2598 /* The type of the function being called. */
2599 tree fntype;
2604 /* Register in which non-BLKmode value will be returned,
2605 or 0 if no value or if value is BLKmode. */
2606 rtx valreg;
2607 /* Address where we should return a BLKmode value;
2608 0 if value not BLKmode. */
2610 /* Nonzero if that address is being passed by treating it as
2611 an extra, implicit first parameter. Otherwise,
2612 it is passed by being copied directly into struct_value_rtx. */
2614 /* Holds the value of implicit argument for the struct value. */
2616 /* Size of aggregate value wanted, or zero if none wanted
2617 or if we are using the non-reentrant PCC calling convention
2618 or expecting the value in registers. */
2620 /* Nonzero if called function returns an aggregate in memory PCC style,
2621 by returning the address of where to find it. */
2625 /* Number of actual parameters in this call, including struct value addr. */
2627 /* Number of named args. Args after this are anonymous ones
2628 and they must all go on the stack. */
2630 /* Number of complex actual arguments that need to be split. */
2633 /* Vector of information about each argument.
2634 Arguments are numbered in the order they will be pushed,
2635 not the order they are written. */
2638 /* Total size in bytes of all the stack-parms scanned so far. */
2641 /* Size of arguments before any adjustments (such as rounding). */
2642 poly_int64 unadjusted_args_size;
2643 /* Data on reg parms scanned so far. */
2644 CUMULATIVE_ARGS args_so_far_v;
2645 cumulative_args_t args_so_far;
2646 /* Nonzero if a reg parm has been scanned. */
2648 /* Nonzero if this is an indirect function call. */
2650 /* Nonzero if we must avoid push-insns in the args for this call.
2651 If stack space is allocated for register parameters, but not by the
2652 caller, then it is preallocated in the fixed part of the stack frame.
2653 So the entire argument block must then be preallocated (i.e., we
2654 ignore PUSH_ROUNDING in that case). */
2658 /* Size of the stack reserved for parameter registers. */
2661 /* Address of space preallocated for stack parms
2662 (on machines that lack push insns), or 0 if space not preallocated. */
2665 /* Mask of ECF_ and ERF_ flags. */
2668 #ifdef REG_PARM_STACK_SPACE
2669 /* Define the boundary of the register parm stack space that needs to be
2670 saved, if any. */
2673 #endif
2680 poly_int64 old_stack_allocated;
2682 /* State variables to track stack modifications. */
2688 /* Some stack pointer alterations we make are performed via
2689 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
2690 which we then also need to save/restore along the way. */
2693 rtx call_fusage;
2696 /* The alignment of the stack, in bits. */
2698 /* The alignment of the stack, in bytes. */
2700 /* The static chain value to use for this call. */
2701 rtx static_chain_value;
2702 /* See if this is "nothrow" function call. */
2706 /* See if we can find a DECL-node for the actual function, and get the
2707 function attributes (flags) from the function decl or type node. */
2710 {
2714 }
2715 else
2716 {
2721 }
2726 /* Warn if this value is an aggregate type,
2727 regardless of which calling convention we are using for it. */
2731 /* If the result of a non looping pure or const function call is
2732 ignored (or void), and none of its arguments are volatile, we can
2733 avoid expanding the call and just evaluate the arguments for
2734 side-effects. */
2740 {
2742 tree arg;
2743 call_expr_arg_iterator iter;
2747 {
2750 }
2753 {
2757 }
2758 }
2760 #ifdef REG_PARM_STACK_SPACE
2762 #endif
2768 /* Set up a place to return a structure. */
2770 /* Cater to broken compilers. */
2772 {
2773 /* This call returns a big structure. */
2776 #ifdef PCC_STATIC_STRUCT_RETURN
2777 {
2779 }
2781 {
2785 /* Even if it is semantically safe to use the target as the return
2786 slot, it may be not sufficiently aligned for the return type. */
2788 && target
2790 /* If rettype is addressable, we may not create a temporary.
2791 If target is properly aligned at runtime and the compiler
2792 just doesn't know about it, it will work fine, otherwise it
2793 will be UB. */
2799 else
2800 {
2801 /* For variable-sized objects, we must be called with a target
2802 specified. If we were to allocate space on the stack here,
2803 we would have no way of knowing when to free it. */
2807 }
2808 }
2810 }
2812 /* Figure out the amount to which the stack should be aligned. */
2815 {
2817 /* Without automatic stack alignment, we can't increase preferred
2818 stack boundary. With automatic stack alignment, it is
2819 unnecessary since unless we can guarantee that all callers will
2820 align the outgoing stack properly, callee has to align its
2821 stack anyway. */
2826 }
2828 /* Operand 0 is a pointer-to-function; get the type of the function. */
2833 /* Count whether there are actual complex arguments that need to be split
2834 into their real and imaginary parts. Munge the type_arg_types
2835 appropriately here as well. */
2837 {
2838 call_expr_arg_iterator iter;
2839 tree arg;
2841 {
2845 num_complex_actuals++;
2846 }
2848 }
2849 else
2855 /* If struct_value_rtx is 0, it means pass the address
2856 as if it were an extra parameter. Put the argument expression
2857 in structure_value_addr_value. */
2859 {
2860 /* If structure_value_addr is a REG other than
2861 virtual_outgoing_args_rtx, we can use always use it. If it
2862 is not a REG, we must always copy it into a register.
2863 If it is virtual_outgoing_args_rtx, we must copy it to another
2864 register in some cases. */
2866 || (ACCUMULATE_OUTGOING_ARGS
2867 && stack_arg_under_construction
2873 structure_value_addr_value =
2876 }
2878 /* Count the arguments and set NUM_ACTUALS. */
2879 num_actuals =
2882 /* Compute number of named args.
2883 First, do a raw count of the args for INIT_CUMULATIVE_ARGS. */
2886 n_named_args
2888 /* Count the struct value address, if it is passed as a parm. */
2890 else
2891 /* If we know nothing, treat all args as named. */
2894 /* Start updating where the next arg would go.
2896 On some machines (such as the PA) indirect calls have a different
2897 calling convention than normal calls. The fourth argument in
2898 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
2899 or not. */
2903 /* Now possibly adjust the number of named args.
2904 Normally, don't include the last named arg if anonymous args follow.
2905 We do include the last named arg if
2906 targetm.calls.strict_argument_naming() returns nonzero.
2907 (If no anonymous args follow, the result of list_length is actually
2908 one too large. This is harmless.)
2910 If targetm.calls.pretend_outgoing_varargs_named() returns
2911 nonzero, and targetm.calls.strict_argument_naming() returns zero,
2912 this machine will be able to place unnamed args that were passed
2913 in registers into the stack. So treat all args as named. This
2914 allows the insns emitting for a specific argument list to be
2915 independent of the function declaration.
2917 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
2918 we do not have any reliable way to pass unnamed args in
2919 registers, so we must force them into memory. */
2923 ;
2926 /* Don't include the last named arg. */
2928 else
2929 /* Treat all args as named. */
2932 /* Make a vector to hold all the information about each arg. */
2935 /* Build up entries in the ARGS array, compute the size of the
2936 arguments into ARGS_SIZE, etc. */
2948 /* Now make final decision about preallocating stack space. */
2953 /* If the structure value address will reference the stack pointer, we
2954 must stabilize it. We don't need to do this if we know that we are
2955 not going to adjust the stack pointer in processing this call. */
2960 structure_value_addr))
2962 || (!ACCUMULATE_OUTGOING_ARGS
2966 /* Tail calls can make things harder to debug, and we've traditionally
2967 pushed these optimizations into -O2. Don't try if we're already
2968 expanding a call, as that means we're an argument. Don't try if
2969 there's cleanups, as we know there's code to follow the call. */
2976 /* Workaround buggy C/C++ wrappers around Fortran routines with
2977 character(len=constant) arguments if the hidden string length arguments
2978 are passed on the stack; if the callers forget to pass those arguments,
2979 attempting to tail call in such routines leads to stack corruption.
2980 Avoid tail calls in functions where at least one such hidden string
2981 length argument is passed (partially or fully) on the stack in the
2982 caller and the callee needs to pass any arguments on the stack.
2983 See PR90329. */
2988 {
2992 {
2995 }
2996 }
2998 /* If the user has marked the function as requiring tail-call
2999 optimization, attempt it. */
3003 /* Rest of purposes for tail call optimizations to fail. */
3006 structure_value_addr,
3007 funtype,
3008 fndecl,
3011 /* Check if caller and callee disagree in promotion of function
3012 return value. */
3014 {
3024 caller_promoted_mode
3028 callee_promoted_mode
3038 {
3041 "caller and callee disagree in"
3042 " promotion of function"
3044 }
3045 }
3047 /* Ensure current function's preferred stack boundary is at least
3048 what we need. Stack alignment may also increase preferred stack
3049 boundary. */
3058 else
3066 /* We want to make two insn chains; one for a sibling call, the other
3067 for a normal call. We will select one of the two chains after
3068 initial RTL generation is complete. */
3070 {
3073 /* We want to emit any pending stack adjustments before the tail
3074 recursion "call". That way we know any adjustment after the tail
3075 recursion call can be ignored if we indeed use the tail
3076 call expansion. */
3077 saved_pending_stack_adjust save;
3079 rtx next_arg_reg;
3082 {
3083 /* State variables we need to save and restore between
3084 iterations. */
3086 }
3089 else
3092 /* Other state variables that we must reinitialize each time
3093 through the loop (that are not initialized by the loop itself). */
3097 /* Start a new sequence for the normal call case.
3099 From this point on, if the sibling call fails, we want to set
3100 sibcall_failure instead of continuing the loop. */
3103 /* Don't let pending stack adjusts add up to too much.
3104 Also, do all pending adjustments now if there is any chance
3105 this might be a call to alloca or if we are expanding a sibling
3106 call sequence.
3107 Also do the adjustments before a throwing call, otherwise
3108 exception handling can fail; PR 19225. */
3117 /* Precompute any arguments as needed. */
3121 /* Now we are about to start emitting insns that can be deleted
3122 if a libcall is deleted. */
3132 /* Compute the actual size of the argument block required. The variable
3133 and constant sizes must be combined, the size may have to be rounded,
3134 and there may be a minimum required size. When generating a sibcall
3135 pattern, do not round up, since we'll be re-using whatever space our
3136 caller provided. */
3137 unadjusted_args_size
3146 /* The argument block when performing a sibling call is the
3147 incoming argument block. */
3149 {
3152 argblock
3154 else
3155 argblock
3162 }
3164 /* If we have no actual push instructions, or shouldn't use them,
3165 make space for all args right now. */
3167 {
3169 {
3174 /* stack_arg_under_construction says whether a stack arg is
3175 being constructed at the old stack level. Pushing the stack
3176 gets a clean outgoing argument block. */
3179 }
3183 }
3184 else
3185 {
3186 /* Note that we must go through the motions of allocating an argument
3187 block even if the size is zero because we may be storing args
3188 in the area reserved for register arguments, which may be part of
3189 the stack frame. */
3193 /* Store the maximum argument space used. It will be pushed by
3194 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
3195 checking). */
3198 needed);
3201 {
3203 {
3204 /* Since the stack pointer will never be pushed, it is
3205 possible for the evaluation of a parm to clobber
3206 something we have already written to the stack.
3207 Since most function calls on RISC machines do not use
3208 the stack, this is uncommon, but must work correctly.
3210 Therefore, we save any area of the stack that was already
3211 written and that we are using. Here we set up to do this
3212 by making a new stack usage map from the old one. The
3213 actual save will be done by store_one_arg.
3215 Another approach might be to try to reorder the argument
3216 evaluations to avoid this conflicting stack usage. */
3218 /* Since we will be writing into the entire argument area,
3219 the map must be allocated for its entire size, not just
3220 the part that is the responsibility of the caller. */
3228 /* For polynomial sizes, this is the maximum possible
3229 size needed for arguments with a constant size
3230 and offset. */
3232 highest_outgoing_arg_in_use
3241 initial_highest_arg_in_use);
3245 (highest_outgoing_arg_in_use
3249 /* The address of the outgoing argument list must not be
3250 copied to a register here, because argblock would be left
3251 pointing to the wrong place after the call to
3252 allocate_dynamic_stack_space below. */
3255 }
3256 else
3257 {
3258 /* Try to reuse some or all of the pending_stack_adjust
3259 to get this space. */
3261 && (combine_pending_stack_adjustment_and_call
3263 unadjusted_args_size,
3265 preferred_unit_stack_boundary)))
3266 {
3267 /* combine_pending_stack_adjustment_and_call computes
3268 an adjustment before the arguments are allocated.
3269 Account for them and see whether or not the stack
3270 needs to go up or down. */
3273 /* Checked by
3274 combine_pending_stack_adjustment_and_call. */
3277 {
3278 /* We're releasing stack space. */
3279 /* ??? We can avoid any adjustment at all if we're
3280 already aligned. FIXME. */
3284 }
3285 else
3286 /* We need to allocate space. We'll do that in
3287 push_block below. */
3289 }
3291 /* Special case this because overhead of `push_block' in
3292 this case is non-trivial. */
3295 else
3296 {
3301 }
3303 /* We only really need to call `copy_to_reg' in the case
3304 where push insns are going to be used to pass ARGBLOCK
3305 to a function call in ARGS. In that case, the stack
3306 pointer changes value from the allocation point to the
3307 call point, and hence the value of
3308 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
3309 as well always do it. */
3311 }
3312 }
3313 }
3316 {
3317 /* The save/restore code in store_one_arg handles all
3318 cases except one: a constructor call (including a C
3319 function returning a BLKmode struct) to initialize
3320 an argument. */
3322 {
3323 rtx push_size
3324 = (gen_int_mode
3330 {
3335 /* stack_arg_under_construction says whether a stack
3336 arg is being constructed at the old stack level.
3337 Pushing the stack gets a clean outgoing argument
3338 block. */
3339 old_stack_arg_under_construction
3342 /* Make a new map for the new argument list. */
3348 }
3349 /* We can pass TRUE as the 4th argument because we just
3350 saved the stack pointer and will restore it right after
3351 the call. */
3354 }
3356 /* If argument evaluation might modify the stack pointer,
3357 copy the address of the argument list to a register. */
3360 {
3363 }
3364 }
3368 /* Stack is properly aligned, pops can't safely be deferred during
3369 the evaluation of the arguments. */
3370 NO_DEFER_POP;
3372 /* Precompute all register parameters. It isn't safe to compute
3373 anything once we have started filling any specific hard regs.
3374 TLS symbols sometimes need a call to resolve. Precompute
3375 register parameters before any stack pointer manipulation
3376 to avoid unaligned stack in the called function. */
3379 OK_DEFER_POP;
3381 /* Perform stack alignment before the first push (the last arg). */
3385 {
3386 /* When the stack adjustment is pending, we get better code
3387 by combining the adjustments. */
3389 && ! inhibit_defer_pop
3390 && (combine_pending_stack_adjustment_and_call
3392 unadjusted_args_size,
3394 preferred_unit_stack_boundary)))
3399 Pmode));
3400 }
3401 /* Now that the stack is properly aligned, pops can't safely
3402 be deferred during the evaluation of the arguments. */
3403 NO_DEFER_POP;
3405 /* Record the maximum pushed stack space size. We need to delay
3406 doing it this far to take into account the optimization done
3407 by combine_pending_stack_adjustment_and_call. */
3409 && !ACCUMULATE_OUTGOING_ARGS
3410 && pass
3412 {
3415 current_function_pushed_stack_size
3417 }
3423 else
3426 #ifdef REG_PARM_STACK_SPACE
3427 /* Save the fixed argument area if it's part of the caller's frame and
3428 is clobbered by argument setup for this call. */
3432 #endif
3434 /* Now store (and compute if necessary) all non-register parms.
3435 These come before register parms, since they can require block-moves,
3436 which could clobber the registers used for register parms.
3437 Parms which have partial registers are not stored here,
3438 but we do preallocate space here if they want that. */
3441 {
3443 {
3446 /* We don't allow passing huge (> 2^30 B) arguments
3447 by value. It would cause an overflow later on. */
3450 {
3452 /* Don't worry about stack clean-up. */
3455 else
3458 }
3462 reg_parm_stack_space)
3467 }
3470 call_fusage
3473 call_fusage);
3474 }
3476 /* If we have a parm that is passed in registers but not in memory
3477 and whose alignment does not permit a direct copy into registers,
3478 make a group of pseudos that correspond to each register that we
3479 will later fill. */
3483 /* Now store any partially-in-registers parm.
3484 This is the last place a block-move can happen. */
3488 {
3491 /* On targets with weird calling conventions (e.g. PA) it's
3492 hard to ensure that all cases of argument overlap between
3493 stack and registers work. Play it safe and bail out. */
3495 {
3498 }
3502 reg_parm_stack_space)
3507 }
3512 {
3515 }
3519 /* Figure out the register where the value, if any, will come back. */
3523 {
3527 else
3531 /* If VALREG is a PARALLEL whose first member has a zero
3532 offset, use that. This is for targets such as m68k that
3533 return the same value in multiple places. */
3535 {
3542 }
3543 }
3545 /* If register arguments require space on the stack and stack space
3546 was not preallocated, allocate stack space here for arguments
3547 passed in registers. */
3549 && !ACCUMULATE_OUTGOING_ARGS
3553 /* Pass the function the address in which to return a
3554 structure value. */
3556 {
3557 structure_value_addr
3562 NULL_RTX)));
3566 }
3576 /* Save a pointer to the last insn before the call, so that we can
3577 later safely search backwards to find the CALL_INSN. */
3580 /* Set up next argument register. For sibling calls on machines
3581 with register windows this should be the incoming register. */
3585 else
3590 {
3596 && valreg
3599 call_fusage
3602 call_fusage);
3603 }
3604 /* All arguments and registers used for the call must be set up by
3605 now! */
3607 /* Stack must be properly aligned now. */
3610 preferred_unit_stack_boundary));
3612 /* Generate the actual call instruction. */
3619 {
3623 {
3627 }
3630 }
3632 /* If the call setup or the call itself overlaps with anything
3633 of the argument setup we probably clobbered our call address.
3634 In that case we can't do sibcalls. */
3639 /* If a non-BLKmode value is returned at the most significant end
3640 of a register, shift the register right by the appropriate amount
3641 and update VALREG accordingly. BLKmode values are handled by the
3642 group load/store machinery below. */
3644 && !pcc_struct_value
3649 {
3653 }
3656 {
3660 /* The return value from a malloc-like function is a pointer. */
3666 /* The return value from a malloc-like function cannot alias
3667 anything else. */
3671 /* Write out the sequence. */
3676 }
3678 /* For calls to `setjmp', etc., inform
3679 function.cc:setjmp_warnings that it should complain if
3680 nonvolatile values are live. For functions that cannot
3681 return, inform flow that control does not fall through. */
3684 {
3685 /* The barrier must be emitted
3686 immediately after the CALL_INSN. Some ports emit more
3687 than just a CALL_INSN above, so we must search for it here. */
3691 {
3693 /* There was no CALL_INSN? */
3695 }
3699 /* Stack adjustments after a noreturn call are dead code.
3700 However when NO_DEFER_POP is in effect, we must preserve
3701 stack_pointer_delta. */
3703 {
3706 }
3707 }
3709 /* If value type not void, return an rtx for the value. */
3715 {
3717 {
3718 target
3721 structure_value_addr));
3723 }
3724 }
3726 {
3727 /* This is the special C++ case where we need to
3728 know what the true target was. We take care to
3729 never use this value more than once in one expression. */
3733 }
3734 /* Handle calls that return values in multiple non-contiguous locations.
3735 The Irix 6 ABI has examples of this. */
3737 {
3741 ;
3743 /* Handle the result of a emit_group_move_into_temps
3744 call in the previous pass. */
3746 else
3749 }
3753 {
3756 /* We have to copy a return value in a CLASS_LIKELY_SPILLED hard
3757 reg to a plain register. */
3761 /* If TARGET is a MEM in the argument area, and we have
3762 saved part of the argument area, then we can't store
3763 directly into TARGET as it may get overwritten when we
3764 restore the argument save area below. Don't work too
3765 hard though and simply force TARGET to a register if it
3766 is a MEM; the optimizer is quite likely to sort it out. */
3770 {
3773 }
3777 else
3778 {
3779 /* TARGET and VALREG cannot be equal at this point
3780 because the latter would not have
3781 REG_FUNCTION_VALUE_P true, while the former would if
3782 it were referring to the same register.
3784 If they refer to the same register, this move will be
3785 a no-op, except when function inlining is being
3786 done. */
3789 /* If we are setting a MEM, this code must be executed.
3790 Since it is emitted after the call insn, sibcall
3791 optimization cannot be performed in that case. */
3794 }
3795 }
3796 else
3799 /* If we promoted this return value, make the proper SUBREG.
3800 TARGET might be const0_rtx here, so be careful. */
3804 {
3807 machine_mode pmode;
3809 /* Ensure we promote as expected, and get the new unsignedness. */
3819 }
3821 /* If size of args is variable or this was a constructor call for a stack
3822 argument, restore saved stack-pointer value. */
3825 {
3840 }
3842 {
3843 #ifdef REG_PARM_STACK_SPACE
3847 #endif
3849 /* If we saved any argument areas, restore them. */
3852 {
3854 rtx stack_area
3861 else
3863 (gen_int_mode
3865 BLOCK_OP_CALL_PARM);
3866 }
3871 }
3873 /* If this was alloca, record the new stack level. */
3877 /* Free up storage we no longer need. */
3887 {
3890 /* Restore the pending stack adjustment now that we have
3891 finished generating the sibling call sequence. */
3895 /* Prepare arg structure for next iteration. */
3897 {
3901 }
3906 }
3907 else
3908 {
3911 /* Verify that we've deallocated all the stack we used. */
3913 || normal_failure
3915 stack_pointer_delta
3919 }
3921 /* If something prevents making this a sibling call,
3922 zero out the sequence. */
3925 else
3927 }
3929 /* If tail call production succeeded, we need to remove REG_EQUIV notes on
3930 arguments too, as argument area is now clobbered by the call. */
3932 {
3935 }
3936 else
3937 {
3940 /* Ideally we'd emit a message for all of the ways that it could
3941 have failed. */
3943 }
3945 currently_expanding_call--;
3950 }
3952 /* A sibling call sequence invalidates any REG_EQUIV notes made for
3953 this function's incoming arguments.
3955 At the start of RTL generation we know the only REG_EQUIV notes
3956 in the rtl chain are those for incoming arguments, so we can look
3957 for REG_EQUIV notes between the start of the function and the
3958 NOTE_INSN_FUNCTION_BEG.
3960 This is (slight) overkill. We could keep track of the highest
3961 argument we clobber and be more selective in removing notes, but it
3962 does not seem to be worth the effort. */
3964 void
3966 {
3970 {
3971 rtx note;
3973 /* There are never REG_EQUIV notes for the incoming arguments
3974 after the NOTE_INSN_FUNCTION_BEG note, so stop if we see it. */
3984 }
3985 }
3987 /* Traverse a list of TYPES and expand all complex types into their
3988 components. */
3989 static tree
3991 {
3992 tree p;
3994 /* Before allocating memory, check for the common case of no complex. */
3996 {
4001 }
4004 found:
4008 {
4013 {
4016 /* Rewrite complex type with component type. */
4020 /* Add another component type for the imaginary part. */
4025 /* Skip the newly created node. */
4027 }
4028 }
4031 }
4032 \f
4033 /* Output a library call to function ORGFUN (a SYMBOL_REF rtx)
4034 for a value of mode OUTMODE,
4035 with NARGS different arguments, passed as ARGS.
4036 Store the return value if RETVAL is nonzero: store it in VALUE if
4037 VALUE is nonnull, otherwise pick a convenient location. In either
4038 case return the location of the stored value.
4040 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for
4041 `const' calls, LCT_PURE for `pure' calls, or another LCT_ value for
4042 other types of library calls. */
4044 rtx
4048 {
4049 /* Total size in bytes of all the stack-parms scanned so far. */
4051 /* Size of arguments before any adjustments (such as rounding). */
4054 rtx fun;
4055 /* Todo, choose the correct decl type of orgfun. Sadly this information
4056 isn't present here, so we default to native calling abi here. */
4061 CUMULATIVE_ARGS args_so_far_v;
4062 cumulative_args_t args_so_far;
4063 struct arg
4064 {
4065 rtx value;
4066 machine_mode mode;
4067 rtx reg;
4070 rtx save_area;
4071 };
4076 rtx valreg;
4081 poly_int64 needed;
4086 #ifdef REG_PARM_STACK_SPACE
4087 /* Define the boundary of the register parm stack space that needs to be
4088 save, if any. */
4091 #endif
4093 /* Size of the stack reserved for parameter registers. */
4101 #ifdef REG_PARM_STACK_SPACE
4103 #endif
4105 /* By default, library functions cannot throw. */
4109 {
4127 }
4130 /* Ensure current function's preferred stack boundary is at least
4131 what we need. */
4135 /* If this kind of value comes back in memory,
4136 decide where in memory it should come back. */
4138 {
4141 {
4142 #ifdef PCC_STATIC_STRUCT_RETURN
4143 rtx pointer_reg
4153 else
4155 #endif
4156 /* This call returns a big structure. */
4158 }
4159 }
4160 else
4163 /* ??? Unfinished: must pass the memory address as an argument. */
4165 /* Copy all the libcall-arguments out of the varargs data
4166 and into a vector ARGVEC.
4168 Compute how to pass each argument. We only support a very small subset
4169 of the full argument passing conventions to limit complexity here since
4170 library functions shouldn't have many args. */
4175 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
4177 #else
4179 #endif
4189 /* If there's a structure value address to be passed,
4190 either pass it in the special place, or pass it as an extra argument. */
4192 {
4195 nargs++;
4197 /* Make sure it is a reasonable operand for a move or push insn. */
4212 #ifdef STACK_PARMS_IN_REG_PARM_AREA
4214 #else
4216 #endif
4226 count++;
4227 }
4230 {
4235 /* We cannot convert the arg value to the mode the library wants here;
4236 must do it earlier where we know the signedness of the arg. */
4241 /* Make sure it is a reasonable operand for a move or push insn. */
4248 {
4249 rtx slot;
4252 /* If this was a CONST function, it is now PURE since it now
4253 reads memory. */
4255 {
4258 }
4261 {
4266 }
4267 else
4268 {
4272 }
4276 call_fusage);
4280 slot),
4281 call_fusage);
4286 }
4292 unsigned_p);
4301 {
4303 #ifdef STACK_PARMS_IN_REG_PARM_AREA
4305 #else
4307 #endif
4312 }
4313 #ifdef BLOCK_REG_PADDING
4314 else
4315 /* The argument is passed entirely in registers. See at which
4316 end it should be padded. */
4320 UNITS_PER_WORD));
4321 #endif
4324 }
4332 /* If this machine requires an external definition for library
4333 functions, write one out. */
4339 STACK_BYTES)
4343 reg_parm_stack_space);
4352 {
4354 current_function_pushed_stack_size
4356 }
4359 {
4360 /* Since the stack pointer will never be pushed, it is possible for
4361 the evaluation of a parm to clobber something we have already
4362 written to the stack. Since most function calls on RISC machines
4363 do not use the stack, this is uncommon, but must work correctly.
4365 Therefore, we save any area of the stack that was already written
4366 and that we are using. Here we set up to do this by making a new
4367 stack usage map from the old one.
4369 Another approach might be to try to reorder the argument
4370 evaluations to avoid this conflicting stack usage. */
4374 /* Since we will be writing into the entire argument area, the
4375 map must be allocated for its entire size, not just the part that
4376 is the responsibility of the caller. */
4384 /* For polynomial sizes, this is the maximum possible size needed
4385 for arguments with a constant size and offset. */
4388 const_limit);
4395 initial_highest_arg_in_use);
4402 /* We must be careful to use virtual regs before they're instantiated,
4403 and real regs afterwards. Loop optimization, for example, can create
4404 new libcalls after we've instantiated the virtual regs, and if we
4405 use virtuals anyway, they won't match the rtl patterns. */
4409 STACK_POINTER_OFFSET);
4410 else
4412 }
4413 else
4414 {
4417 }
4419 /* We push args individually in reverse order, perform stack alignment
4420 before the first push (the last arg). */
4424 Pmode));
4428 #ifdef REG_PARM_STACK_SPACE
4430 {
4431 /* The argument list is the property of the called routine and it
4432 may clobber it. If the fixed area has been used for previous
4433 parameters, we must save and restore it. */
4436 }
4437 #endif
4439 /* When expanding a normal call, args are stored in push order,
4440 which is the reverse of what we have here. */
4444 {
4447 }
4451 /* Push the args that need to be pushed. */
4455 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4456 are to be pushed. */
4458 {
4467 {
4468 rtx use;
4471 {
4472 /* If this is being stored into a pre-allocated, fixed-size,
4473 stack area, save any previous data at that location. */
4476 {
4477 /* stack_slot is negative, but we want to index stack_usage_map
4478 with positive values. */
4481 }
4482 else
4483 {
4486 }
4489 reg_parm_stack_space))
4490 {
4491 /* We need to make a save area. */
4492 poly_uint64 size
4494 machine_mode save_mode
4496 rtx adr
4499 rtx stack_area
4503 {
4507 );
4511 stack_area,
4512 (gen_int_mode
4514 Pmode)),
4515 BLOCK_OP_CALL_PARM);
4516 }
4517 else
4518 {
4522 }
4523 }
4524 }
4528 (gen_int_mode
4530 reg_parm_stack_space,
4533 /* Now mark the segment we just used. */
4537 NO_DEFER_POP;
4539 /* Indicate argument access so that alias.cc knows that these
4540 values are live. */
4546 else
4547 {
4548 /* When arguments are pushed, trying to tell alias.cc where
4549 exactly this argument is won't work, because the
4550 auto-increment causes confusion. So we merely indicate
4551 that we access something with a known mode somewhere on
4552 the stack. */
4556 }
4560 }
4561 }
4567 /* Now load any reg parms into their regs. */
4569 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
4570 are to be pushed. */
4572 {
4578 /* Handle calls that pass values in multiple non-contiguous
4579 locations. The PA64 has examples of this for library calls. */
4583 {
4585 #ifdef BLOCK_REG_PADDING
4588 /* Copied from load_register_parameters. */
4590 /* Handle case where we have a value that needs shifting
4591 up to the msb. eg. a QImode value and we're padding
4592 upward on a BYTES_BIG_ENDIAN machine. */
4596 {
4597 rtx x;
4600 /* Assigning REG here rather than a temp makes CALL_FUSAGE
4601 report the whole reg as used. Strictly speaking, the
4602 call only uses SIZE bytes at the msb end, but it doesn't
4603 seem worth generating rtl to say that. */
4608 }
4609 #endif
4610 }
4612 NO_DEFER_POP;
4613 }
4615 /* Any regs containing parms remain in use through the call. */
4617 {
4622 {
4625 {
4630 }
4631 else
4633 }
4634 }
4636 /* Pass the function the address in which to return a structure value. */
4638 {
4642 NULL_RTX)));
4645 }
4647 /* Don't allow popping to be deferred, since then
4648 cse'ing of library calls could delete a call and leave the pop. */
4649 NO_DEFER_POP;
4653 /* Stack must be properly aligned now. */
4662 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
4663 will set inhibit_defer_pop to that value. */
4664 /* The return type is needed to decide how many bytes the function pops.
4665 Signedness plays no role in that, so for simplicity, we pretend it's
4666 always signed. We also assume that the list of arguments passed has
4667 no impact, so we pretend it is unknown. */
4673 struct_value_size,
4676 valreg,
4680 {
4685 }
4687 /* Right-shift returned value if necessary. */
4691 {
4694 }
4698 /* For calls to `setjmp', etc., inform function.cc:setjmp_warnings
4699 that it should complain if nonvolatile values are live. For
4700 functions that cannot return, inform flow that control does not
4701 fall through. */
4703 {
4704 /* The barrier note must be emitted
4705 immediately after the CALL_INSN. Some ports emit more than
4706 just a CALL_INSN above, so we must search for it here. */
4709 {
4711 /* There was no CALL_INSN? */
4713 }
4716 }
4718 /* Consider that "regular" libcalls, i.e. all of them except for LCT_THROW
4719 and LCT_RETURNS_TWICE, cannot perform non-local gotos. */
4721 {
4724 {
4726 /* There was no CALL_INSN? */
4728 }
4731 }
4733 /* Now restore inhibit_defer_pop to its actual original value. */
4734 OK_DEFER_POP;
4738 /* Copy the value to the right place. */
4740 {
4742 {
4747 }
4749 {
4753 }
4754 else
4755 {
4756 /* Convert to the proper mode if a promotion has been active. */
4758 {
4765 }
4769 else
4771 }
4772 }
4775 {
4776 #ifdef REG_PARM_STACK_SPACE
4780 #endif
4782 /* If we saved any argument areas, restore them. */
4785 {
4794 validize_mem
4796 (gen_int_mode
4798 BLOCK_OP_CALL_PARM);
4799 else
4801 }
4806 }
4812 }
4813 \f
4815 /* Store a single argument for a function call
4816 into the register or memory area where it must be passed.
4817 *ARG describes the argument value and where to pass it.
4819 ARGBLOCK is the address of the stack-block for all the arguments,
4820 or 0 on a machine where arguments are pushed individually.
4822 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
4823 so must be careful about how the stack is used.
4825 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
4826 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
4827 that we need not worry about saving and restoring the stack.
4829 FNDECL is the declaration of the function we are calling.
4831 Return nonzero if this arg should cause sibcall failure,
4832 zero otherwise. */
4834 static int
4837 {
4848 /* Push a new temporary level for any temporaries we make for
4849 this argument. */
4853 {
4854 /* If this is being stored into a pre-allocated, fixed-size, stack area,
4855 save any previous data at that location. */
4857 {
4859 {
4860 /* stack_slot is negative, but we want to index stack_usage_map
4861 with positive values. */
4863 {
4866 }
4867 else
4871 }
4872 else
4873 {
4875 {
4878 }
4879 else
4883 }
4886 reg_parm_stack_space))
4887 {
4888 /* We need to make a save area. */
4890 machine_mode save_mode
4896 {
4897 arg->save_area
4901 stack_area,
4902 (gen_int_mode
4904 BLOCK_OP_CALL_PARM);
4905 }
4906 else
4907 {
4910 }
4911 }
4912 }
4913 }
4915 /* If this isn't going to be placed on both the stack and in registers,
4916 set up the register and number of words. */
4918 {
4921 else
4924 }
4926 /* Being passed entirely in a register. We shouldn't be called in
4927 this case. */
4930 /* If this arg needs special alignment, don't load the registers
4931 here. */
4935 /* If this is being passed partially in a register, we can't evaluate
4936 it directly into its stack slot. Otherwise, we can. */
4938 {
4939 /* stack_arg_under_construction is nonzero if a function argument is
4940 being evaluated directly into the outgoing argument list and
4941 expand_call must take special action to preserve the argument list
4942 if it is called recursively.
4944 For scalar function arguments stack_usage_map is sufficient to
4945 determine which stack slots must be saved and restored. Scalar
4946 arguments in general have pass_on_stack == 0.
4948 If this argument is initialized by a function which takes the
4949 address of the argument (a C++ constructor or a C function
4950 returning a BLKmode structure), then stack_usage_map is
4951 insufficient and expand_call must push the stack around the
4952 function call. Such arguments have pass_on_stack == 1.
4954 Note that it is always safe to set stack_arg_under_construction,
4955 but this generates suboptimal code if set when not needed. */
4958 stack_arg_under_construction++;
4961 (partial
4966 /* If we are promoting object (or for any other reason) the mode
4967 doesn't agree, convert the mode. */
4974 stack_arg_under_construction--;
4975 }
4977 /* Check for overlap with already clobbered argument area. */
4984 /* Don't allow anything left on stack from computation
4985 of argument to alloca. */
4990 /* If the value is already in the stack slot, we are done. */
4991 ;
4993 {
4996 /* Argument is a scalar, not entirely passed in registers.
4997 (If part is passed in registers, arg->partial says how much
4998 and emit_push_insn will take care of putting it there.)
5000 Push it, and if its size is less than the
5001 amount of space allocated to it,
5002 also bump stack pointer by the additional space.
5003 Note that in C the default argument promotions
5004 will prevent such mismatches. */
5009 /* Compute how much space the push instruction will push.
5010 On many machines, pushing a byte will advance the stack
5011 pointer by a halfword. */
5012 #ifdef PUSH_ROUNDING
5014 #endif
5017 /* Compute how much space the argument should get:
5018 round up to a multiple of the alignment for arguments. */
5021 /* At the moment we don't (need to) support ABIs for which the
5022 padding isn't known at compile time. In principle it should
5023 be easy to add though. */
5026 /* Compute the alignment of the pushed argument. */
5030 {
5035 }
5037 /* This isn't already where we want it on the stack, so put it there.
5038 This can either be done with push or copy insns. */
5043 reg_parm_stack_space,
5047 /* Unless this is a partially-in-register argument, the argument is now
5048 in the stack. */
5051 }
5052 else
5053 {
5054 /* BLKmode, at least partly to be pushed. */
5057 poly_int64 excess;
5058 rtx size_rtx;
5060 /* Pushing a nonscalar.
5061 If part is passed in registers, PARTIAL says how much
5062 and emit_push_insn will take care of putting it there. */
5064 /* Round its size up to a multiple
5065 of the allocation unit for arguments. */
5068 {
5071 }
5072 else
5073 {
5074 /* PUSH_ROUNDING has no effect on us, because emit_push_insn
5075 for BLKmode is careful to avoid it. */
5081 EXPAND_NORMAL);
5082 }
5086 /* When an argument is padded down, the block is aligned to
5087 PARM_BOUNDARY, but the actual argument isn't. */
5090 {
5093 else
5094 {
5095 unsigned int excess_align
5099 }
5100 }
5103 {
5104 /* emit_push_insn might not work properly if arg->value and
5105 argblock + arg->locate.offset areas overlap. */
5111 {
5112 /* arg.locate doesn't contain the pretend_args_size offset,
5113 it's part of argblock. Ensure we don't count it in I. */
5116 else
5119 /* expand_call should ensure this. */
5125 {
5126 /* Even though they appear to be at the same location,
5127 if part of the outgoing argument is in registers,
5128 they aren't really at the same location. Check for
5129 this by making sure that the incoming size is the
5130 same as the outgoing size. */
5133 }
5137 /* Use arg->locate.size.constant instead of size_rtx
5138 because we only care about the part of the argument
5139 on the stack. */
5143 }
5144 }
5150 reg_parm_stack_space,
5152 /* If we bypass emit_push_insn because it is a zero sized argument,
5153 we still might need to adjust stack if such argument requires
5154 extra alignment. See PR104558. */
5160 /* Unless this is a partially-in-register argument, the argument is now
5161 in the stack.
5163 ??? Unlike the case above, in which we want the actual
5164 address of the data, so that we can load it directly into a
5165 register, here we want the address of the stack slot, so that
5166 it's properly aligned for word-by-word copying or something
5167 like that. It's not clear that this is always correct. */
5170 }
5173 {
5175 arg->parallel_value
5178 }
5180 /* Mark all slots this store used. */
5185 /* Once we have pushed something, pops can't safely
5186 be deferred during the rest of the arguments. */
5187 NO_DEFER_POP;
5189 /* Free any temporary slots made in processing this argument. */
5193 }
5195 /* Nonzero if we do not know how to pass ARG solely in registers. */
5197 bool
5199 {
5203 /* If the type has variable size... */
5207 /* If the type is marked as addressable (it is required
5208 to be constructed into the stack)... */
5213 }
5215 /* Another version of the TARGET_MUST_PASS_IN_STACK hook. This one
5216 takes trailing padding of a structure into account. */
5217 /* ??? Should be able to merge these two by examining BLOCK_REG_PADDING. */
5219 bool
5221 {
5225 /* If the type has variable size... */
5229 /* If the type is marked as addressable (it is required
5230 to be constructed into the stack)... */
5237 /* If the padding and mode of the type is such that a copy into
5238 a register would put it into the wrong part of the register. */
5246 }
5248 /* Return true if TYPE must be passed on the stack when passed to
5249 the "..." arguments of a function. */
5251 bool
5253 {
5256 }
5258 /* Return true if FIELD is the C++17 empty base field that should
5259 be ignored for ABI calling convention decisions in order to
5260 maintain ABI compatibility between C++14 and earlier, which doesn't
5261 add this FIELD to classes with empty bases, and C++17 and later
5262 which does. */
5264 bool
5266 {
5271 }