| blob | 8ac94db68176f6dd2d00a59432b972c02460419b |
1 /* Convert function calls to rtl insns, for GNU C compiler.
2 Copyright (C) 1989-2020 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/>. */
61 /* Like PREFERRED_STACK_BOUNDARY but in units of bytes, not bits. */
62 #define STACK_BYTES (PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT)
64 /* Data structure and subroutines used within expand_call. */
66 struct arg_data
67 {
68 /* Tree node for this argument. */
69 tree tree_value;
70 /* Mode for value; TYPE_MODE unless promoted. */
71 machine_mode mode;
72 /* Current RTL value for argument, or 0 if it isn't precomputed. */
73 rtx value;
74 /* Initially-compute RTL value for argument; only for const functions. */
75 rtx initial_value;
76 /* Register to pass this argument in, 0 if passed on stack, or an
77 PARALLEL if the arg is to be copied into multiple non-contiguous
78 registers. */
79 rtx reg;
80 /* Register to pass this argument in when generating tail call sequence.
81 This is not the same register as for normal calls on machines with
82 register windows. */
83 rtx tail_call_reg;
84 /* If REG is a PARALLEL, this is a copy of VALUE pulled into the correct
85 form for emit_group_move. */
86 rtx parallel_value;
87 /* If REG was promoted from the actual mode of the argument expression,
88 indicates whether the promotion is sign- or zero-extended. */
90 /* Number of bytes to put in registers. 0 means put the whole arg
91 in registers. Also 0 if not passed in registers. */
93 /* Nonzero if argument must be passed on stack.
94 Note that some arguments may be passed on the stack
95 even though pass_on_stack is zero, just because FUNCTION_ARG says so.
96 pass_on_stack identifies arguments that *cannot* go in registers. */
98 /* Some fields packaged up for locate_and_pad_parm. */
100 /* Location on the stack at which parameter should be stored. The store
101 has already been done if STACK == VALUE. */
102 rtx stack;
103 /* Location on the stack of the start of this argument slot. This can
104 differ from STACK if this arg pads downward. This location is known
105 to be aligned to TARGET_FUNCTION_ARG_BOUNDARY. */
106 rtx stack_slot;
107 /* Place that this stack area has been saved, if needed. */
108 rtx save_area;
109 /* If an argument's alignment does not permit direct copying into registers,
110 copy in smaller-sized pieces into pseudos. These are stored in a
111 block pointed to by this field. The next field says how many
112 word-sized pseudos we made. */
115 };
117 /* A vector of one char per byte of stack space. A byte if nonzero if
118 the corresponding stack location has been used.
119 This vector is used to prevent a function call within an argument from
120 clobbering any stack already set up. */
123 /* Size of STACK_USAGE_MAP. */
126 /* Assume that any stack location at this byte index is used,
127 without checking the contents of stack_usage_map. */
130 /* A bitmap of virtual-incoming stack space. Bit is set if the corresponding
131 stack location's tail call argument has been already stored into the stack.
132 This bitmap is used to prevent sibling call optimization if function tries
133 to use parent's incoming argument slots when they have been already
134 overwritten with tail call arguments. */
137 /* Assume that any virtual-incoming location at this byte index has been
138 stored, without checking the contents of stored_args_map. */
141 /* stack_arg_under_construction is nonzero when an argument may be
142 initialized with a constructor call (including a C function that
143 returns a BLKmode struct) and expand_call must take special action
144 to make sure the object being constructed does not overlap the
145 argument list for the constructor call. */
164 #ifdef REG_PARM_STACK_SPACE
167 #endif
168 \f
169 /* Return true if bytes [LOWER_BOUND, UPPER_BOUND) of the outgoing
170 stack region might already be in use. */
172 static bool
175 {
184 /* Don't worry about things in the fixed argument area;
185 it has already been saved. */
192 }
194 /* Record that bytes [LOWER_BOUND, UPPER_BOUND) of the outgoing
195 stack region are now in use. */
197 static void
199 {
205 else
207 }
209 /* Force FUNEXP into a form suitable for the address of a CALL,
210 and return that as an rtx. Also load the static chain register
211 if FNDECL is a nested function.
213 CALL_FUSAGE points to a variable holding the prospective
214 CALL_INSN_FUNCTION_USAGE information. */
216 rtx
219 {
220 /* Make a valid memory address and copy constants through pseudo-regs,
221 but not for a constant address if -fno-function-cse. */
223 {
224 /* If it's an indirect call by descriptor, generate code to perform
225 runtime identification of the pointer and load the descriptor. */
227 {
232 fndecl_or_type
234 fndecl_or_type);
241 /* Avoid long live ranges around function calls. */
247 /* Emit the runtime identification pattern. */
250 call_lab);
252 /* Statically predict the branch to very likely taken. */
257 /* Load the descriptor. */
266 POINTER_SIZE / BITS_PER_UNIT
275 {
278 }
280 /* Make sure we're not going to be overwritten below. */
282 }
284 /* If we are using registers for parameters, force the
285 function address into a register now. */
286 funexp = ((reg_parm_seen
290 }
291 else
292 {
293 /* funexp could be a SYMBOL_REF represents a function pointer which is
294 of ptr_mode. In this case, it should be converted into address mode
295 to be a valid address for memory rtx pattern. See PR 64971. */
300 {
303 }
304 }
309 {
310 rtx chain;
317 {
320 }
321 }
324 }
326 /* Generate instructions to call function FUNEXP,
327 and optionally pop the results.
328 The CALL_INSN is the first insn generated.
330 FNDECL is the declaration node of the function. This is given to the
331 hook TARGET_RETURN_POPS_ARGS to determine whether this function pops
332 its own args.
334 FUNTYPE is the data type of the function. This is given to the hook
335 TARGET_RETURN_POPS_ARGS to determine whether this function pops its
336 own args. We used to allow an identifier for library functions, but
337 that doesn't work when the return type is an aggregate type and the
338 calling convention says that the pointer to this aggregate is to be
339 popped by the callee.
341 STACK_SIZE is the number of bytes of arguments on the stack,
342 ROUNDED_STACK_SIZE is that number rounded up to
343 PREFERRED_STACK_BOUNDARY; zero if the size is variable. This is
344 both to put into the call insn and to generate explicit popping
345 code if necessary.
347 STRUCT_VALUE_SIZE is the number of bytes wanted in a structure value.
348 It is zero if this call doesn't want a structure value.
350 NEXT_ARG_REG is the rtx that results from executing
351 targetm.calls.function_arg (&args_so_far,
352 function_arg_info::end_marker ());
353 just after all the args have had their registers assigned.
354 This could be whatever you like, but normally it is the first
355 arg-register beyond those used for args in this call,
356 or 0 if all the arg-registers are used in this call.
357 It is passed on to `gen_call' so you can put this info in the call insn.
359 VALREG is a hard register in which a value is returned,
360 or 0 if the call does not return a value.
362 OLD_INHIBIT_DEFER_POP is the value that `inhibit_defer_pop' had before
363 the args to this call were processed.
364 We restore `inhibit_defer_pop' to that value.
366 CALL_FUSAGE is either empty or an EXPR_LIST of USE expressions that
367 denote registers used by the called function. */
369 static void
371 tree funtype ATTRIBUTE_UNUSED,
372 poly_int64 stack_size ATTRIBUTE_UNUSED,
373 poly_int64 rounded_stack_size,
374 poly_int64 struct_value_size ATTRIBUTE_UNUSED,
377 cumulative_args_t args_so_far ATTRIBUTE_UNUSED)
378 {
384 /* Sibling call patterns never pop arguments (no sibcall(_value)_pop
385 patterns exist). Any popping that the callee does on return will
386 be from our caller's frame rather than ours. */
388 {
391 #ifdef CALL_POPS_ARGS
393 #endif
394 }
396 /* Ensure address is valid. SYMBOL_REF is already valid, so no need,
397 and we don't want to load it into a register as an optimization,
398 because prepare_call_address already did it if it should be done. */
404 {
407 /* Although a built-in FUNCTION_DECL and its non-__builtin
408 counterpart compare equal and get a shared mem_attrs, they
409 produce different dump output in compare-debug compilations,
410 if an entry gets garbage collected in one compilation, then
411 adds a different (but equivalent) entry, while the other
412 doesn't run the garbage collector at the same spot and then
413 shares the mem_attr with the equivalent entry. */
415 {
419 }
422 }
427 {
430 rounded_stack_size_rtx,
432 else
434 next_arg_reg,
436 }
437 /* If the target has "call" or "call_value" insns, then prefer them
438 if no arguments are actually popped. If the target does not have
439 "call" or "call_value" insns, then we must use the popping versions
440 even if the call has no arguments to pop. */
442 || !(valreg
445 {
448 /* If this subroutine pops its own args, record that in the call insn
449 if possible, for the sake of frame pointer elimination. */
453 rounded_stack_size_rtx,
455 else
460 }
461 else
462 {
466 else
469 }
472 /* Find the call we just emitted. */
475 /* Some target create a fresh MEM instead of reusing the one provided
476 above. Set its MEM_EXPR. */
483 /* Put the register usage information there. */
486 /* If this is a const call, then set the insn's unchanging bit. */
490 /* If this is a pure call, then set the insn's unchanging bit. */
494 /* If this is a const call, then set the insn's unchanging bit. */
498 /* Create a nothrow REG_EH_REGION note, if needed. */
505 {
508 }
512 /* Restore this now, so that we do defer pops for this call's args
513 if the context of the call as a whole permits. */
517 {
529 /* If popup is needed, stack realign must use DRAP */
532 }
533 /* For noreturn calls when not accumulating outgoing args force
534 REG_ARGS_SIZE note to prevent crossjumping of calls with different
535 args sizes. */
540 {
541 /* If returning from the subroutine does not automatically pop the args,
542 we need an instruction to pop them sooner or later.
543 Perhaps do it now; perhaps just record how much space to pop later.
545 If returning from the subroutine does pop the args, indicate that the
546 stack pointer will be changed. */
549 {
551 /* Just pretend we did the pop. */
556 else
558 }
559 }
560 /* When we accumulate outgoing args, we must avoid any stack manipulations.
561 Restore the stack pointer to its original value now. Usually
562 ACCUMULATE_OUTGOING_ARGS targets don't get here, but there are exceptions.
563 On i386 ACCUMULATE_OUTGOING_ARGS can be enabled on demand, and
564 popping variants of functions exist as well.
566 ??? We may optimize similar to defer_pop above, but it is
567 probably not worthwhile.
569 ??? It will be worthwhile to enable combine_stack_adjustments even for
570 such machines. */
573 }
575 /* Determine if the function identified by FNDECL is one with
576 special properties we wish to know about. Modify FLAGS accordingly.
578 For example, if the function might return more than one time (setjmp), then
579 set ECF_RETURNS_TWICE.
581 Set ECF_MAY_BE_ALLOCA for any memory allocation function that might allocate
582 space from the stack such as alloca. */
584 static int
586 {
591 {
595 /* We assume that alloca will always be called by name. It
596 makes no sense to pass it as a pointer-to-function to
597 anything that does not understand its behavior. */
603 /* Disregard prefix _ or __. */
605 {
608 else
610 }
612 /* ECF_RETURNS_TWICE is safe even for -ffreestanding. */
619 }
626 }
628 /* Similar to special_function_p; return a set of ERF_ flags for the
629 function FNDECL. */
630 static int
632 {
633 tree attr;
647 {
660 }
661 }
663 /* Return nonzero when FNDECL represents a call to setjmp. */
665 int
667 {
671 }
674 /* Return true if STMT may be an alloca call. */
676 bool
678 {
679 tree fndecl;
689 }
691 /* Return true if STMT is a builtin alloca call. */
693 bool
695 {
696 tree fndecl;
704 {
705 CASE_BUILT_IN_ALLOCA:
709 }
712 }
714 /* Return true when exp contains a builtin alloca call. */
716 bool
718 {
719 tree fndecl;
724 {
725 CASE_BUILT_IN_ALLOCA:
729 }
732 }
734 /* Return TRUE if FNDECL is either a TM builtin or a TM cloned
735 function. Return FALSE otherwise. */
737 static bool
739 {
747 {
749 {
792 }
793 }
795 }
797 /* Detect flags (function attributes) from the function decl or type node. */
799 int
801 {
805 {
806 /* The function exp may have the `malloc' attribute. */
810 /* The function exp may have the `returns_twice' attribute. */
814 /* Process the pure and const attributes. */
833 {
840 }
843 }
845 {
853 }
854 else
858 {
862 }
865 }
867 /* Detect flags from a CALL_EXPR. */
869 int
871 {
879 else
880 {
884 else
888 }
891 }
893 /* Return true if ARG should be passed by invisible reference. */
895 bool
897 {
899 {
900 /* If this type contains non-trivial constructors, then it is
901 forbidden for the middle-end to create any new copies. */
905 /* GCC post 3.4 passes *all* variable sized types by reference. */
909 /* If a record type should be passed the same as its first (and only)
910 member, use the type and mode of that member. */
912 {
915 }
916 }
919 }
921 /* Return true if TYPE should be passed by reference when passed to
922 the "..." arguments of a function. */
924 bool
926 {
928 }
930 /* Decide whether ARG, which occurs in the state described by CA,
931 should be passed by reference. Return true if so and update
932 ARG accordingly. */
934 bool
936 {
938 {
943 }
945 }
947 /* Return true if ARG, which is passed by reference, should be callee
948 copied instead of caller copied. */
950 bool
952 {
956 }
959 /* Precompute all register parameters as described by ARGS, storing values
960 into fields within the ARGS array.
962 NUM_ACTUALS indicates the total number elements in the ARGS array.
964 Set REG_PARM_SEEN if we encounter a register parameter. */
966 static void
969 {
976 {
980 {
985 }
987 /* If we are to promote the function arg to a wider mode,
988 do it now. */
996 /* If the value is a non-legitimate constant, force it into a
997 pseudo now. TLS symbols sometimes need a call to resolve. */
1002 /* If we're going to have to load the value by parts, pull the
1003 parts into pseudos. The part extraction process can involve
1004 non-trivial computation. */
1006 {
1011 }
1013 /* If the value is expensive, and we are inside an appropriately
1014 short loop, put the value into a pseudo and then put the pseudo
1015 into the hard reg.
1017 For small register classes, also do this if this call uses
1018 register parameters. This is to avoid reload conflicts while
1019 loading the parameters registers. */
1028 && ((*reg_parm_seen
1032 }
1033 }
1035 #ifdef REG_PARM_STACK_SPACE
1037 /* The argument list is the property of the called routine and it
1038 may clobber it. If the fixed area has been used for previous
1039 parameters, we must save and restore it. */
1041 static rtx
1042 save_fixed_argument_area (int reg_parm_stack_space, rtx argblock, int *low_to_save, int *high_to_save)
1043 {
1047 /* Compute the boundary of the area that needs to be saved, if any. */
1057 {
1059 machine_mode save_mode;
1061 rtx addr;
1062 rtx stack_area;
1063 rtx save_area;
1066 ;
1073 /* If we don't have the required alignment, must do this
1074 in BLKmode. */
1075 scalar_int_mode imode;
1080 else
1085 else
1093 {
1097 }
1098 else
1099 {
1102 }
1105 }
1108 }
1110 static void
1112 {
1119 else
1128 else
1131 BLOCK_OP_CALL_PARM);
1132 }
1135 /* If any elements in ARGS refer to parameters that are to be passed in
1136 registers, but not in memory, and whose alignment does not permit a
1137 direct copy into registers. Copy the values into a group of pseudos
1138 which we will later copy into the appropriate hard registers.
1140 Pseudos for each unaligned argument will be stored into the array
1141 args[argnum].aligned_regs. The caller is responsible for deallocating
1142 the aligned_regs array if it is nonzero. */
1144 static void
1146 {
1156 {
1161 {
1164 }
1165 else
1166 {
1169 }
1173 /* Structures smaller than a word are normally aligned to the
1174 least significant byte. On a BYTES_BIG_ENDIAN machine,
1175 this means we must skip the empty high order bytes when
1176 calculating the bit offset. */
1178 #ifdef BLOCK_REG_PADDING
1182 #else
1183 && BYTES_BIG_ENDIAN
1184 #endif
1185 )
1189 {
1198 /* There is no need to restrict this code to loading items
1199 in TYPE_ALIGN sized hunks. The bitfield instructions can
1200 load up entire word sized registers efficiently.
1202 ??? This may not be needed anymore.
1203 We use to emit a clobber here but that doesn't let later
1204 passes optimize the instructions we emit. By storing 0 into
1205 the register later passes know the first AND to zero out the
1206 bitfield being set in the register is unnecessary. The store
1207 of 0 will be deleted as will at least the first AND. */
1214 }
1215 }
1216 }
1218 /* The limit set by -Walloc-larger-than=. */
1221 /* Initialize ALLOC_OBJECT_SIZE_LIMIT based on the -Walloc-size-larger-than=
1222 setting if the option is specified, or to the maximum object size if it
1223 is not. Return the initialized value. */
1225 static tree
1227 {
1238 }
1240 /* Return true when EXP's range can be determined and set RANGE[] to it
1241 after adjusting it if necessary to make EXP a represents a valid size
1242 of object, or a valid size argument to an allocation function declared
1243 with attribute alloc_size (whose argument may be signed), or to a string
1244 manipulation function like memset. When ALLOW_ZERO is true, allow
1245 returning a range of [0, 0] for a size in an anti-range [1, N] where
1246 N > PTRDIFF_MAX. A zero range is a (nearly) invalid argument to
1247 allocation functions like malloc but it is a valid argument to
1248 functions like memset. */
1250 bool
1252 {
1257 {
1258 /* EXP is a constant. */
1261 }
1271 else
1275 {
1277 {
1278 /* Use the full range of the type of the expression when
1279 no value range information is available. */
1283 }
1288 }
1295 {
1297 {
1299 {
1300 /* EXP is not in a strictly negative range. That means
1301 it must be in some (not necessarily strictly) positive
1302 range which includes zero. Since in signed to unsigned
1303 conversions negative values end up converted to large
1304 positive values, and otherwise they are not valid sizes,
1305 the resulting range is in both cases [0, TYPE_MAX]. */
1308 }
1310 {
1311 /* EXP is not in a negative-positive range. That means EXP
1312 is either negative, or greater than max. Since negative
1313 sizes are invalid make the range [MAX + 1, TYPE_MAX]. */
1316 }
1317 else
1318 {
1321 }
1322 }
1324 {
1325 /* EXP is unsigned and not in the range [1, MAX]. That means
1326 it's either zero or greater than MAX. Even though 0 would
1327 normally be detected by -Walloc-zero, unless ALLOW_ZERO
1328 is true, set the range to [MAX, TYPE_MAX] so that when MAX
1329 is greater than the limit the whole range is diagnosed. */
1332 else
1333 {
1336 }
1337 }
1338 else
1339 {
1342 }
1343 }
1349 }
1351 /* Diagnose a call EXP to function FN decorated with attribute alloc_size
1352 whose argument numbers given by IDX with values given by ARGS exceed
1353 the maximum object size or cause an unsigned oveflow (wrapping) when
1354 multiplied. FN is null when EXP is a call via a function pointer.
1355 When ARGS[0] is null the function does nothing. ARGS[1] may be null
1356 for functions like malloc, and non-null for those like calloc that
1357 are decorated with a two-argument attribute alloc_size. */
1359 void
1361 {
1362 /* The range each of the (up to) two arguments is known to be in. */
1365 /* Maximum object size set by -Walloc-size-larger-than= or SIZE_MAX / 2. */
1373 /* Validate each argument individually. */
1375 {
1377 {
1382 {
1386 }
1388 {
1389 /* Avoid issuing -Walloc-zero for allocation functions other
1390 than __builtin_alloca that are declared with attribute
1391 returns_nonnull because there's no portability risk. This
1392 avoids warning for such calls to libiberty's xmalloc and
1393 friends.
1394 Also avoid issuing the warning for calls to function named
1395 "alloca". */
1403 }
1405 {
1406 /* G++ emits calls to ::operator new[](SIZE_MAX) in C++98
1407 mode and with -fno-exceptions as a way to indicate array
1408 size overflow. There's no good way to detect C++98 here
1409 so avoid diagnosing these calls for all C++ modes. */
1411 && fn
1419 "%Kargument %i value %qE exceeds "
1422 }
1423 }
1426 {
1427 /* Verify that the argument's range is not negative (including
1428 upper bound of zero). */
1431 {
1436 }
1438 {
1440 "%Kargument %i range [%E, %E] exceeds "
1444 maxobjsize);
1445 }
1446 }
1447 }
1452 /* For a two-argument alloc_size, validate the product of the two
1453 arguments if both of their values or ranges are known. */
1458 {
1459 /* Check for overflow in the product of a function decorated with
1460 attribute alloc_size (X, Y). */
1470 "%Kproduct %<%E * %E%> of arguments %i and %i "
1476 "%Kproduct %<%E * %E%> of arguments %i and %i "
1480 maxobjsize);
1483 {
1484 /* Print the full range of each of the two arguments to make
1485 it clear when it is, in fact, in a range and not constant. */
1492 }
1493 }
1496 {
1502 else
1505 }
1506 }
1508 /* If EXPR refers to a character array or pointer declared attribute
1509 nonstring return a decl for that array or pointer and set *REF to
1510 the referenced enclosing object or pointer. Otherwise returns
1511 null. */
1513 tree
1515 {
1519 {
1523 {
1529 }
1530 else
1532 }
1537 /* To simplify calling code, store the referenced DECL regardless of
1538 the attribute determined below, but avoid storing the SSA_NAME_VAR
1539 obtained above (it's not useful for dataflow purposes). */
1543 /* Use the SSA_NAME_VAR that was determined above to see if it's
1544 declared nonstring. Otherwise drill down into the referenced
1545 DECL. */
1560 }
1562 /* Warn about passing a non-string array/pointer to a built-in function
1563 that expects a nul-terminated string argument. Returns true if
1564 a warning has been issued.*/
1566 bool
1568 {
1575 /* Avoid clearly invalid calls (more checking done below). */
1580 /* The bound argument to a bounded string function like strncpy. */
1583 /* The longest known or possible string argument to one of the comparison
1584 functions. If the length is less than the bound it is used instead.
1585 Since the length is only used for warning and not for code generation
1586 disable strict mode in the calls to get_range_strlen below. */
1589 /* It's safe to call "bounded" string functions with a non-string
1590 argument since the functions provide an explicit bound for this
1591 purpose. The exception is strncat where the bound may refer to
1592 either the destination or the source. */
1595 {
1599 {
1600 /* For these, if one argument refers to one or more of a set
1601 of string constants or arrays of known size, determine
1602 the range of their known or possible lengths and use it
1603 conservatively as the bound for the unbounded function,
1604 and to adjust the range of the bound of the bounded ones. */
1608 {
1611 {
1612 c_strlen_data lendata = { };
1613 /* Set MAXBOUND to an arbitrary non-null non-integer
1614 node as a request to have it set to the length of
1615 the longest string in a PHI. */
1619 }
1620 }
1621 }
1622 /* Fall through. */
1637 {
1640 {
1641 c_strlen_data lendata = { };
1642 /* Set MAXBOUND to an arbitrary non-null non-integer
1643 node as a request to have it set to the length of
1644 the longest string in a PHI. */
1648 }
1652 }
1656 }
1658 /* Determine the range of the bound argument (if specified). */
1661 {
1664 }
1669 {
1670 /* Diagnose excessive bound prior to the adjustment below and
1671 regardless of attribute nonstring. */
1674 {
1678 "%K%qD specified bound %E "
1681 else
1683 "%K%qD specified bound [%E, %E] "
1686 maxobjsize);
1691 }
1692 }
1695 {
1696 /* Add one for the nul. */
1698 size_one_node);
1701 {
1702 /* Conservatively use the upper bound of the lengths for
1703 both the lower and the upper bound of the operation. */
1707 }
1709 {
1710 /* Replace the bound on the operation with the upper bound
1711 of the length of the string if the latter is smaller. */
1716 }
1717 }
1720 /* Iterate over the built-in function's formal arguments and check
1721 each const char* against the actual argument. If the actual
1722 argument is declared attribute non-string issue a warning unless
1723 the argument's maximum length is bounded. */
1724 function_args_iterator it;
1728 {
1729 /* Avoid iterating past the declared argument in a call
1730 to function declared without a prototype. */
1755 /* See if the destination is declared with attribute "nonstring". */
1760 /* The maximum number of array elements accessed. */
1764 {
1765 /* See if the bound in strncat is derived from the length
1766 of the strlen of the destination (as it's expected to be).
1767 If so, reset BOUND and FNCODE to trigger a warning. */
1770 {
1771 /* The bound applies to the destination, not to the source,
1772 so reset these to trigger a warning without mentioning
1773 the bound. */
1776 }
1778 /* Use the upper bound of the range for strncat. */
1780 }
1782 /* Use the lower bound of the range for functions other than
1783 strncat. */
1786 /* Determine the size of the argument array if it is one. */
1791 /* Determine the array size. For arrays of unknown bound and
1792 pointers reset BOUND to trigger the appropriate warning. */
1794 {
1796 {
1798 {
1801 }
1802 }
1805 }
1809 /* In a call to strncat with a bound in a range whose lower but
1810 not upper bound is less than the array size, reset ASIZE to
1811 be the same as the bound and the other variable to trigger
1812 the apprpriate warning below. */
1816 && (!known_size
1818 {
1822 }
1826 auto_diagnostic_group d;
1828 {
1831 "%qD argument %i declared attribute "
1832 "%<nonstring%> is smaller than the specified "
1837 "%qD argument %i declared attribute "
1838 "%<nonstring%> is smaller than "
1841 else
1843 "%qD argument %i declared attribute "
1844 "%<nonstring%> may be smaller than "
1847 }
1850 is equal to the size of the non-string argument. */
1857 {
1861 }
1862 }
1868 }
1870 /* Issue an error if CALL_EXPR was flagged as requiring
1871 tall-call optimization. */
1873 static void
1875 {
1881 }
1883 /* Returns the type of the argument ARGNO to function with type FNTYPE
1884 or null when the typoe cannot be determined or no such argument exists. */
1886 static tree
1888 {
1892 tree argtype;
1893 function_args_iterator it;
1899 }
1901 /* Helper to append the "rdwr" attribute specification described
1902 by ACCESS to the array ATTRSTR with size STRSIZE. Used in
1903 diagnostics. */
1908 {
1909 /* Append the relevant attribute to the string. This (deliberately)
1910 appends the attribute pointer operand even when none was specified. */
1927 else
1931 }
1933 /* Iterate over attribute access read-only, read-write, and write-only
1934 arguments and diagnose past-the-end accesses and related problems
1935 in the function call EXP. */
1937 static void
1939 {
1940 auto_diagnostic_group adg;
1942 /* A string describing the attributes that the warnings issued by this
1943 function apply to. Used to print one informational note per function
1944 call, rather than one per warning. That reduces clutter. */
1949 {
1952 /* Get the function call arguments corresponding to the attribute's
1953 positional arguments. When both arguments have been specified
1954 there will be two entries in *RWM, one for each. They are
1955 cross-referenced by their respective argument numbers in
1956 ACCESS.PTRARG and ACCESS.SIZARG. */
1963 /* The pointer is set to null for the entry corresponding to
1964 the size argument. Skip it. It's handled when the entry
1965 corresponding to the pointer argument comes up. */
1972 tree size;
1974 {
1975 /* If only the pointer attribute operand was specified
1976 and not size, set SIZE to the size of one element of
1977 the pointed to type to detect smaller objects (null
1978 pointers are diagnosed in this case only if
1979 the pointer is also declared with attribute nonnull. */
1981 }
1982 else
1990 {
1991 /* Warn about negative sizes. */
1998 else
2003 {
2005 /* Avoid warning again for the same attribute. */
2007 }
2008 }
2011 {
2013 {
2014 /* Multiple SIZE by the size of the type the pointer
2015 argument points to. If it's incomplete the size
2016 is used as is. */
2020 {
2025 }
2026 }
2027 }
2028 else
2034 {
2035 /* Warn about null pointers with positive sizes. This is
2036 different from also declaring the pointer argument with
2037 attribute nonnull when the function accepts null pointers
2038 only when the corresponding size is zero. */
2043 "%Kargument %i is null but the corresponding "
2046 else
2048 "%Kargument %i is null but the corresponding "
2053 {
2055 /* Avoid warning again for the same attribute. */
2057 }
2058 }
2062 tree srcsize;
2064 {
2065 /* For a write-only argument there is no source. */
2067 }
2068 else
2069 {
2070 /* For read-only and read-write attributes also set the source
2071 size. */
2075 {
2076 /* For a read-only attribute there is no destination so
2077 clear OBJSIZE. This emits "reading N bytes" kind of
2078 diagnostics instead of the "writing N bytes" kind,
2079 unless MODE is none. */
2081 }
2082 }
2084 /* Clear the no-warning bit in case it was set in a prior
2085 iteration so that accesses via different arguments are
2086 diagnosed. */
2092 /* If check_access issued a warning above, append the relevant
2093 attribute to the string. */
2095 }
2104 else
2109 /* Set the bit in case if was cleared and not set above. */
2111 }
2113 /* Fill in ARGS_SIZE and ARGS array based on the parameters found in
2114 CALL_EXPR EXP.
2116 NUM_ACTUALS is the total number of parameters.
2118 N_NAMED_ARGS is the total number of named arguments.
2120 STRUCT_VALUE_ADDR_VALUE is the implicit argument for a struct return
2121 value, or null.
2123 FNDECL is the tree code for the target of this call (if known)
2125 ARGS_SO_FAR holds state needed by the target to know where to place
2126 the next argument.
2128 REG_PARM_STACK_SPACE is the number of bytes of stack space reserved
2129 for arguments which are passed in registers.
2131 OLD_STACK_LEVEL is a pointer to an rtx which olds the old stack level
2132 and may be modified by this routine.
2134 OLD_PENDING_ADJ, MUST_PREALLOCATE and FLAGS are pointers to integer
2135 flags which may be modified by this routine.
2137 MAY_TAILCALL is cleared if we encounter an invisible pass-by-reference
2138 that requires allocation of stack space.
2140 CALL_FROM_THUNK_P is true if this call is the jump from a thunk to
2141 the thunked-to function. */
2143 static void
2150 cumulative_args_t args_so_far,
2156 {
2160 /* Count arg position in order args appear. */
2170 /* In this loop, we consider args in the order they are written.
2171 We fill up ARGS from the back. */
2174 {
2176 call_expr_arg_iterator iter;
2177 tree arg;
2181 {
2183 j--;
2184 }
2187 {
2191 && argtype
2194 {
2197 j--;
2199 }
2200 else
2202 j--;
2203 argpos++;
2204 }
2208 }
2212 /* Extract attribute alloc_size from the type of the called expression
2213 (which could be a function or a function pointer) and if set, store
2214 the indices of the corresponding arguments in ALLOC_IDX, and then
2215 the actual argument(s) at those indices in ALLOC_ARGS. */
2219 {
2224 }
2226 /* Array for up to the two attribute alloc_size arguments. */
2229 /* Map of attribute accewss specifications for function arguments. */
2230 rdwr_map rdwr_idx;
2233 /* I counts args in order (to be) pushed; ARGPOS counts in order written. */
2235 {
2239 /* Replace erroneous argument with constant zero. */
2243 /* If TYPE is a transparent union or record, pass things the way
2244 we would pass the first field of the union or record. We have
2245 already verified that the modes are the same. */
2249 /* Decide where to pass this arg.
2251 args[i].reg is nonzero if all or part is passed in registers.
2253 args[i].partial is nonzero if part but not all is passed in registers,
2254 and the exact value says how many bytes are passed in registers.
2256 args[i].pass_on_stack is nonzero if the argument must at least be
2257 computed on the stack. It may then be loaded back into registers
2258 if args[i].reg is nonzero.
2260 These decisions are driven by the FUNCTION_... macros and must agree
2261 with those made by function.c. */
2263 /* See if this argument should be passed by invisible reference. */
2266 {
2272 /* If we're compiling a thunk, pass through invisible references
2273 instead of making a copy. */
2275 || (callee_copies
2280 {
2281 /* We may have turned the parameter value into an SSA name.
2282 Go back to the original parameter so we can take the
2283 address. */
2285 {
2289 }
2290 /* Argument setup code may have copied the value to register. We
2291 revert that optimization now because the tail call code must
2292 use the original location. */
2302 /* We can't use sibcalls if a callee-copied argument is
2303 stored in the current function's frame. */
2305 {
2308 "a callee-copied argument is"
2309 " stored in the current"
2311 }
2319 }
2320 else
2321 {
2322 /* We make a copy of the object and pass the address to the
2323 function being called. */
2324 rtx copy;
2331 {
2332 /* This is a variable-sized object. Make space on the stack
2333 for it. */
2337 {
2341 }
2343 /* We can pass TRUE as the 4th argument because we just
2344 saved the stack pointer and will restore it right after
2345 the call. */
2349 max_int_size_in_bytes
2354 }
2355 else
2360 /* Just change the const function to pure and then let
2361 the next test clear the pure based on
2362 callee_copies. */
2364 {
2367 }
2377 "argument must be passed"
2379 }
2381 }
2385 arg.mode
2399 /* If this is a sibling call and the machine has register windows, the
2400 register window has to be unwinded before calling the routine, so
2401 arguments have to go into the incoming registers. */
2405 else
2413 /* If FUNCTION_ARG returned a (parallel [(expr_list (nil) ...) ...]),
2414 it means that we are to pass this arg in the register(s) designated
2415 by the PARALLEL, but also to pass it in the stack. */
2420 /* If this is an addressable type, we must preallocate the stack
2421 since we must evaluate the object into its final location.
2423 If this is to be passed in both registers and the stack, it is simpler
2424 to preallocate. */
2429 /* Compute the stack-size of this argument. */
2434 #ifdef STACK_PARMS_IN_REG_PARM_AREA
2436 #else
2438 #endif
2439 reg_parm_stack_space,
2442 #ifdef BLOCK_REG_PADDING
2443 else
2444 /* The argument is passed entirely in registers. See at which
2445 end it should be padded. */
2449 #endif
2451 /* Update ARGS_SIZE, the total stack space for args so far. */
2457 /* Increment ARGS_SO_FAR, which has info about which arg-registers
2458 have been used, etc. */
2460 /* ??? Traditionally we've passed TYPE_MODE here, instead of the
2461 promoted_mode used for function_arg above. However, the
2462 corresponding handling of incoming arguments in function.c
2463 does pass the promoted mode. */
2467 /* Store argument values for functions decorated with attribute
2468 alloc_size. */
2474 /* Save the actual argument that corresponds to the access attribute
2475 operand for later processing. */
2477 {
2479 {
2482 }
2483 else
2484 {
2487 }
2488 }
2489 }
2492 {
2493 /* Check the arguments of functions decorated with attribute
2494 alloc_size. */
2496 }
2498 /* Detect passing non-string arguments to functions expecting
2499 nul-terminated strings. */
2502 /* Check attribute access arguments. */
2504 }
2506 /* Update ARGS_SIZE to contain the total size for the argument block.
2507 Return the original constant component of the argument block's size.
2509 REG_PARM_STACK_SPACE holds the number of bytes of stack space reserved
2510 for arguments passed in registers. */
2512 static poly_int64
2515 tree fndecl ATTRIBUTE_UNUSED,
2516 tree fntype ATTRIBUTE_UNUSED,
2518 {
2521 /* For accumulate outgoing args mode we don't need to align, since the frame
2522 will be already aligned. Align to STACK_BOUNDARY in order to prevent
2523 backends from generating misaligned frame sizes. */
2527 /* Compute the actual size of the argument block required. The variable
2528 and constant sizes must be combined, the size may have to be rounded,
2529 and there may be a minimum required size. */
2532 {
2538 {
2539 /* We don't handle this case yet. To handle it correctly we have
2540 to add the delta, round and subtract the delta.
2541 Currently no machine description requires this support. */
2543 preferred_stack_boundary));
2545 }
2548 {
2549 args_size->var
2553 /* The area corresponding to register parameters is not to count in
2554 the size of the block we need. So make the adjustment. */
2556 args_size->var
2559 }
2560 }
2561 else
2562 {
2568 preferred_stack_boundary)
2572 reg_parm_stack_space);
2576 }
2578 }
2580 /* Precompute parameters as needed for a function call.
2582 FLAGS is mask of ECF_* constants.
2584 NUM_ACTUALS is the number of arguments.
2586 ARGS is an array containing information for each argument; this
2587 routine fills in the INITIAL_VALUE and VALUE fields for each
2588 precomputed argument. */
2590 static void
2592 {
2595 /* If this is a libcall, then precompute all arguments so that we do not
2596 get extraneous instructions emitted as part of the libcall sequence. */
2598 /* If we preallocated the stack space, and some arguments must be passed
2599 on the stack, then we must precompute any parameter which contains a
2600 function call which will store arguments on the stack.
2601 Otherwise, evaluating the parameter may clobber previous parameters
2602 which have already been stored into the stack. (we have code to avoid
2603 such case by saving the outgoing stack arguments, but it results in
2604 worse code) */
2609 {
2610 tree type;
2611 machine_mode mode;
2616 /* If this is an addressable type, we cannot pre-evaluate it. */
2625 {
2631 /* CSE will replace this only if it contains args[i].value
2632 pseudo, so convert it down to the declared mode using
2633 a SUBREG. */
2637 {
2642 }
2643 }
2644 }
2645 }
2647 /* Given the current state of MUST_PREALLOCATE and information about
2648 arguments to a function call in NUM_ACTUALS, ARGS and ARGS_SIZE,
2649 compute and return the final value for MUST_PREALLOCATE. */
2651 static int
2654 {
2655 /* See if we have or want to preallocate stack space.
2657 If we would have to push a partially-in-regs parm
2658 before other stack parms, preallocate stack space instead.
2660 If the size of some parm is not a multiple of the required stack
2661 alignment, we must preallocate.
2663 If the total size of arguments that would otherwise create a copy in
2664 a temporary (such as a CALL) is more than half the total argument list
2665 size, preallocation is faster.
2667 Another reason to preallocate is if we have a machine (like the m88k)
2668 where stack alignment is required to be maintained between every
2669 pair of insns, not just when the call is made. However, we assume here
2670 that such machines either do not have push insns (and hence preallocation
2671 would occur anyway) or the problem is taken care of with
2672 PUSH_ROUNDING. */
2675 {
2681 {
2692 copy_to_evaluate_size
2694 }
2699 }
2701 }
2703 /* If we preallocated stack space, compute the address of each argument
2704 and store it into the ARGS array.
2706 We need not ensure it is a valid memory address here; it will be
2707 validized when it is used.
2709 ARGBLOCK is an rtx for the address of the outgoing arguments. */
2711 static void
2713 {
2715 {
2721 {
2724 }
2727 {
2730 rtx addr;
2735 /* Skip this parm if it will not be passed on the stack. */
2748 {
2749 /* Only part of the parameter is being passed on the stack.
2750 Generate a simple memory reference of the correct size. */
2756 }
2757 else
2758 {
2762 }
2765 poly_int64 offset_val;
2769 {
2771 unsigned int offset_align
2775 }
2782 {
2783 /* Only part of the parameter is being passed on the stack.
2784 Generate a simple memory reference of the correct size.
2785 */
2788 }
2789 else
2790 {
2794 }
2797 /* Function incoming arguments may overlap with sibling call
2798 outgoing arguments and we cannot allow reordering of reads
2799 from function arguments with stores to outgoing arguments
2800 of sibling calls. */
2803 }
2804 }
2805 }
2807 /* Given a FNDECL and EXP, return an rtx suitable for use as a target address
2808 in a call instruction.
2810 FNDECL is the tree node for the target function. For an indirect call
2811 FNDECL will be NULL_TREE.
2813 ADDR is the operand 0 of CALL_EXPR for this call. */
2815 static rtx
2817 {
2818 rtx funexp;
2820 /* Get the function to call, in the form of RTL. */
2822 {
2826 /* Get a SYMBOL_REF rtx for the function address. */
2828 }
2829 else
2830 /* Generate an rtx (probably a pseudo-register) for the address. */
2831 {
2835 }
2837 }
2839 /* Return the static chain for this function, if any. */
2841 rtx
2843 {
2848 }
2850 /* Internal state for internal_arg_pointer_based_exp and its helpers. */
2851 static struct
2852 {
2853 /* Last insn that has been scanned by internal_arg_pointer_based_exp_scan,
2854 or NULL_RTX if none has been scanned yet. */
2856 /* Vector indexed by REGNO - FIRST_PSEUDO_REGISTER, recording if a pseudo is
2857 based on crtl->args.internal_arg_pointer. The element is NULL_RTX if the
2858 pseudo isn't based on it, a CONST_INT offset if the pseudo is based on it
2859 with fixed offset, or PC if this is with variable or unknown offset. */
2865 /* Helper function for internal_arg_pointer_based_exp. Scan insns in
2866 the tail call sequence, starting with first insn that hasn't been
2867 scanned yet, and note for each pseudo on the LHS whether it is based
2868 on crtl->args.internal_arg_pointer or not, and what offset from that
2869 that pointer it has. */
2871 static void
2873 {
2878 else
2882 {
2885 {
2888 /* Punt on pseudos set multiple times. */
2893 else
2896 {
2898 internal_arg_pointer_exp_state.cache
2901 }
2902 }
2906 }
2909 }
2911 /* Compute whether RTL is based on crtl->args.internal_arg_pointer. Return
2912 NULL_RTX if RTL isn't based on it, a CONST_INT offset if RTL is based on
2913 it with fixed offset, or PC if this is with variable or unknown offset.
2914 TOPLEVEL is true if the function is invoked at the topmost level. */
2916 static rtx
2918 {
2928 poly_int64 offset;
2930 {
2935 }
2937 /* When called at the topmost level, scan pseudo assignments in between the
2938 last scanned instruction in the tail call sequence and the latest insn
2939 in that sequence. */
2944 {
2950 }
2954 {
2960 }
2963 }
2965 /* Return true if SIZE bytes starting from address ADDR might overlap an
2966 already-clobbered argument area. This function is used to determine
2967 if we should give up a sibcall. */
2969 static bool
2971 {
2972 poly_int64 i;
2974 rtx val;
2990 else
2996 /* We can ignore any references to the function's pretend args,
2997 which at this point would manifest as negative values of I. */
3014 }
3016 /* Do the register loads required for any wholly-register parms or any
3017 parms which are passed both on the stack and in a register. Their
3018 expressions were already evaluated.
3020 Mark all register-parms as living through the call, putting these USE
3021 insns in the CALL_INSN_FUNCTION_USAGE field.
3023 When IS_SIBCALL, perform the check_sibcall_argument_overlap
3024 checking, setting *SIBCALL_FAILURE if appropriate. */
3026 static void
3030 {
3034 {
3038 {
3047 /* Set non-negative if we must move a word at a time, even if
3048 just one word (e.g, partial == 4 && mode == DFmode). Set
3049 to -1 if we just use a normal move insn. This value can be
3050 zero if the argument is a zero size structure. */
3053 ;
3055 {
3058 }
3060 {
3061 /* Variable-sized parameters should be described by a
3062 PARALLEL instead. */
3067 }
3068 else
3071 /* Handle calls that pass values in multiple non-contiguous
3072 locations. The Irix 6 ABI has examples of this. */
3077 /* If simple case, just do move. If normal partial, store_one_arg
3078 has already loaded the register for us. In all other cases,
3079 load the register(s) from memory. */
3082 {
3084 #ifdef BLOCK_REG_PADDING
3085 /* Handle case where we have a value that needs shifting
3086 up to the msb. eg. a QImode value and we're padding
3087 upward on a BYTES_BIG_ENDIAN machine. */
3090 {
3093 {
3094 rtx x;
3095 poly_int64 shift
3098 /* Assigning REG here rather than a temp makes
3099 CALL_FUSAGE report the whole reg as used.
3100 Strictly speaking, the call only uses SIZE
3101 bytes at the msb end, but it doesn't seem worth
3102 generating rtl to say that. */
3108 }
3109 }
3110 #endif
3111 }
3113 /* If we have pre-computed the values to put in the registers in
3114 the case of non-aligned structures, copy them in now. */
3122 {
3123 /* SIZE and CONST_SIZE are 0 for partial arguments and
3124 the size of a BLKmode type otherwise. */
3128 /* Check for overlap with already clobbered argument area,
3129 providing that this has non-zero size. */
3132 && (mem_might_overlap_already_clobbered_arg_p
3139 else
3140 {
3149 NULL);
3155 }
3157 /* Handle a BLKmode that needs shifting. */
3159 #ifdef BLOCK_REG_PADDING
3161 #else
3162 && BYTES_BIG_ENDIAN
3163 #endif
3164 )
3165 {
3170 rtx x;
3175 }
3176 }
3178 /* When a parameter is a block, and perhaps in other cases, it is
3179 possible that it did a load from an argument slot that was
3180 already clobbered. */
3185 /* Handle calls that pass values in multiple non-contiguous
3186 locations. The Irix 6 ABI has examples of this. */
3193 }
3194 }
3195 }
3197 /* We need to pop PENDING_STACK_ADJUST bytes. But, if the arguments
3198 wouldn't fill up an even multiple of PREFERRED_UNIT_STACK_BOUNDARY
3199 bytes, then we would need to push some additional bytes to pad the
3200 arguments. So, we try to compute an adjust to the stack pointer for an
3201 amount that will leave the stack under-aligned by UNADJUSTED_ARGS_SIZE
3202 bytes. Then, when the arguments are pushed the stack will be perfectly
3203 aligned.
3205 Return true if this optimization is possible, storing the adjustment
3206 in ADJUSTMENT_OUT and setting ARGS_SIZE->CONSTANT to the number of
3207 bytes that should be popped after the call. */
3209 static bool
3211 poly_int64 unadjusted_args_size,
3214 {
3215 /* The number of bytes to pop so that the stack will be
3216 under-aligned by UNADJUSTED_ARGS_SIZE bytes. */
3217 poly_int64 adjustment;
3218 /* The alignment of the stack after the arguments are pushed, if we
3219 just pushed the arguments without adjust the stack here. */
3223 preferred_unit_stack_boundary,
3227 /* We want to get rid of as many of the PENDING_STACK_ADJUST bytes
3228 as possible -- leaving just enough left to cancel out the
3229 UNADJUSTED_ALIGNMENT. In other words, we want to ensure that the
3230 PENDING_STACK_ADJUST is non-negative, and congruent to
3231 -UNADJUSTED_ALIGNMENT modulo the PREFERRED_UNIT_STACK_BOUNDARY. */
3233 /* Begin by trying to pop all the bytes. */
3236 preferred_unit_stack_boundary,
3241 /* Push enough additional bytes that the stack will be aligned
3242 after the arguments are pushed. */
3246 /* We need to know whether the adjusted argument size
3247 (UNADJUSTED_ARGS_SIZE - ADJUSTMENT) constitutes an allocation
3248 or a deallocation. */
3252 /* Now, sets ARGS_SIZE->CONSTANT so that we pop the right number of
3253 bytes after the call. The right number is the entire
3254 PENDING_STACK_ADJUST less our ADJUSTMENT plus the amount required
3255 by the arguments in the first place. */
3256 args_size->constant
3261 }
3263 /* Scan X expression if it does not dereference any argument slots
3264 we already clobbered by tail call arguments (as noted in stored_args_map
3265 bitmap).
3266 Return nonzero if X expression dereferences such argument slots,
3267 zero otherwise. */
3269 static int
3271 {
3272 RTX_CODE code;
3281 /* We need not check the operands of the CALL expression itself. */
3289 /* Scan all subexpressions. */
3292 {
3294 {
3297 }
3299 {
3303 }
3304 }
3306 }
3308 /* Scan sequence after INSN if it does not dereference any argument slots
3309 we already clobbered by tail call arguments (as noted in stored_args_map
3310 bitmap). If MARK_STORED_ARGS_MAP, add stack slots for ARG to
3311 stored_args_map bitmap afterwards (when ARG is a register MARK_STORED_ARGS_MAP
3312 should be 0). Return nonzero if sequence after INSN dereferences such argument
3313 slots, zero otherwise. */
3315 static int
3318 {
3324 else
3333 {
3336 else
3344 else
3346 }
3348 }
3350 /* Given that a function returns a value of mode MODE at the most
3351 significant end of hard register VALUE, shift VALUE left or right
3352 as specified by LEFT_P. Return true if some action was needed. */
3354 bool
3356 {
3364 /* Use ashr rather than lshr for right shifts. This is for the benefit
3365 of the MIPS port, which requires SImode values to be sign-extended
3366 when stored in 64-bit registers. */
3372 }
3374 /* If X is a likely-spilled register value, copy it to a pseudo
3375 register and return that register. Return X otherwise. */
3377 static rtx
3379 {
3380 rtx new_rtx;
3385 {
3386 /* Make sure that we generate a REG rather than a CONCAT.
3387 Moves into CONCATs can need nontrivial instructions,
3388 and the whole point of this function is to avoid
3389 using the hard register directly in such a situation. */
3395 }
3397 }
3399 /* Helper function for expand_call.
3400 Return false is EXP is not implementable as a sibling call. */
3402 static bool
3404 rtx structure_value_addr,
3405 tree funtype,
3407 tree fndecl,
3409 tree addr,
3411 {
3413 {
3414 maybe_complain_about_tail_call
3416 "machine description does not have"
3419 }
3421 /* Doing sibling call optimization needs some work, since
3422 structure_value_addr can be allocated on the stack.
3423 It does not seem worth the effort since few optimizable
3424 sibling calls will return a structure. */
3426 {
3429 }
3431 #ifdef REG_PARM_STACK_SPACE
3432 /* If outgoing reg parm stack space changes, we cannot do sibcall. */
3436 {
3438 "inconsistent size of stack space"
3439 " allocated for arguments which are"
3442 }
3443 #endif
3445 /* Check whether the target is able to optimize the call
3446 into a sibcall. */
3448 {
3450 "target is not able to optimize the"
3453 }
3455 /* Functions that do not return exactly once may not be sibcall
3456 optimized. */
3458 {
3461 }
3463 {
3466 }
3469 {
3472 }
3474 /* If the called function is nested in the current one, it might access
3475 some of the caller's arguments, but could clobber them beforehand if
3476 the argument areas are shared. */
3478 {
3481 }
3483 /* If this function requires more stack slots than the current
3484 function, we cannot change it into a sibling call.
3485 crtl->args.pretend_args_size is not part of the
3486 stack allocated by our caller. */
3489 {
3491 "callee required more stack slots"
3494 }
3496 /* If the callee pops its own arguments, then it must pop exactly
3497 the same number of arguments as the current function. */
3501 TREE_TYPE
3504 {
3506 "inconsistent number of"
3509 }
3512 {
3516 }
3518 /* All checks passed. */
3520 }
3522 /* Update stack alignment when the parameter is passed in the stack
3523 since the outgoing parameter requires extra alignment on the calling
3524 function side. */
3526 static void
3528 {
3533 }
3535 /* Generate all the code for a CALL_EXPR exp
3536 and return an rtx for its value.
3537 Store the value in TARGET (specified as an rtx) if convenient.
3538 If the value is stored in TARGET then TARGET is returned.
3539 If IGNORE is nonzero, then we ignore the value of the function call. */
3541 rtx
3543 {
3544 /* Nonzero if we are currently expanding a call. */
3547 /* RTX for the function to be called. */
3548 rtx funexp;
3549 /* Sequence of insns to perform a normal "call". */
3551 /* Sequence of insns to perform a tail "call". */
3553 /* Data type of the function. */
3554 tree funtype;
3555 tree type_arg_types;
3556 tree rettype;
3557 /* Declaration of the function being called,
3558 or 0 if the function is computed (not known by name). */
3560 /* The type of the function being called. */
3561 tree fntype;
3566 /* Register in which non-BLKmode value will be returned,
3567 or 0 if no value or if value is BLKmode. */
3568 rtx valreg;
3569 /* Address where we should return a BLKmode value;
3570 0 if value not BLKmode. */
3572 /* Nonzero if that address is being passed by treating it as
3573 an extra, implicit first parameter. Otherwise,
3574 it is passed by being copied directly into struct_value_rtx. */
3576 /* Holds the value of implicit argument for the struct value. */
3578 /* Size of aggregate value wanted, or zero if none wanted
3579 or if we are using the non-reentrant PCC calling convention
3580 or expecting the value in registers. */
3582 /* Nonzero if called function returns an aggregate in memory PCC style,
3583 by returning the address of where to find it. */
3587 /* Number of actual parameters in this call, including struct value addr. */
3589 /* Number of named args. Args after this are anonymous ones
3590 and they must all go on the stack. */
3592 /* Number of complex actual arguments that need to be split. */
3595 /* Vector of information about each argument.
3596 Arguments are numbered in the order they will be pushed,
3597 not the order they are written. */
3600 /* Total size in bytes of all the stack-parms scanned so far. */
3603 /* Size of arguments before any adjustments (such as rounding). */
3604 poly_int64 unadjusted_args_size;
3605 /* Data on reg parms scanned so far. */
3606 CUMULATIVE_ARGS args_so_far_v;
3607 cumulative_args_t args_so_far;
3608 /* Nonzero if a reg parm has been scanned. */
3610 /* Nonzero if this is an indirect function call. */
3612 /* Nonzero if we must avoid push-insns in the args for this call.
3613 If stack space is allocated for register parameters, but not by the
3614 caller, then it is preallocated in the fixed part of the stack frame.
3615 So the entire argument block must then be preallocated (i.e., we
3616 ignore PUSH_ROUNDING in that case). */
3620 /* Size of the stack reserved for parameter registers. */
3623 /* Address of space preallocated for stack parms
3624 (on machines that lack push insns), or 0 if space not preallocated. */
3627 /* Mask of ECF_ and ERF_ flags. */
3630 #ifdef REG_PARM_STACK_SPACE
3631 /* Define the boundary of the register parm stack space that needs to be
3632 saved, if any. */
3635 #endif
3642 poly_int64 old_stack_allocated;
3644 /* State variables to track stack modifications. */
3650 /* Some stack pointer alterations we make are performed via
3651 allocate_dynamic_stack_space. This modifies the stack_pointer_delta,
3652 which we then also need to save/restore along the way. */
3655 rtx call_fusage;
3658 /* The alignment of the stack, in bits. */
3660 /* The alignment of the stack, in bytes. */
3662 /* The static chain value to use for this call. */
3663 rtx static_chain_value;
3664 /* See if this is "nothrow" function call. */
3668 /* See if we can find a DECL-node for the actual function, and get the
3669 function attributes (flags) from the function decl or type node. */
3672 {
3676 }
3677 else
3678 {
3683 }
3688 /* Warn if this value is an aggregate type,
3689 regardless of which calling convention we are using for it. */
3693 /* If the result of a non looping pure or const function call is
3694 ignored (or void), and none of its arguments are volatile, we can
3695 avoid expanding the call and just evaluate the arguments for
3696 side-effects. */
3701 {
3703 tree arg;
3704 call_expr_arg_iterator iter;
3708 {
3711 }
3714 {
3718 }
3719 }
3721 #ifdef REG_PARM_STACK_SPACE
3723 #endif
3729 /* Set up a place to return a structure. */
3731 /* Cater to broken compilers. */
3733 {
3734 /* This call returns a big structure. */
3737 #ifdef PCC_STATIC_STRUCT_RETURN
3738 {
3740 }
3742 {
3746 /* Even if it is semantically safe to use the target as the return
3747 slot, it may be not sufficiently aligned for the return type. */
3749 && target
3751 /* If rettype is addressable, we may not create a temporary.
3752 If target is properly aligned at runtime and the compiler
3753 just doesn't know about it, it will work fine, otherwise it
3754 will be UB. */
3760 else
3761 {
3762 /* For variable-sized objects, we must be called with a target
3763 specified. If we were to allocate space on the stack here,
3764 we would have no way of knowing when to free it. */
3768 }
3769 }
3771 }
3773 /* Figure out the amount to which the stack should be aligned. */
3776 {
3778 /* Without automatic stack alignment, we can't increase preferred
3779 stack boundary. With automatic stack alignment, it is
3780 unnecessary since unless we can guarantee that all callers will
3781 align the outgoing stack properly, callee has to align its
3782 stack anyway. */
3787 }
3789 /* Operand 0 is a pointer-to-function; get the type of the function. */
3794 /* Count whether there are actual complex arguments that need to be split
3795 into their real and imaginary parts. Munge the type_arg_types
3796 appropriately here as well. */
3798 {
3799 call_expr_arg_iterator iter;
3800 tree arg;
3802 {
3806 num_complex_actuals++;
3807 }
3809 }
3810 else
3816 /* If struct_value_rtx is 0, it means pass the address
3817 as if it were an extra parameter. Put the argument expression
3818 in structure_value_addr_value. */
3820 {
3821 /* If structure_value_addr is a REG other than
3822 virtual_outgoing_args_rtx, we can use always use it. If it
3823 is not a REG, we must always copy it into a register.
3824 If it is virtual_outgoing_args_rtx, we must copy it to another
3825 register in some cases. */
3827 || (ACCUMULATE_OUTGOING_ARGS
3828 && stack_arg_under_construction
3834 structure_value_addr_value =
3837 }
3839 /* Count the arguments and set NUM_ACTUALS. */
3840 num_actuals =
3843 /* Compute number of named args.
3844 First, do a raw count of the args for INIT_CUMULATIVE_ARGS. */
3847 n_named_args
3849 /* Count the struct value address, if it is passed as a parm. */
3851 else
3852 /* If we know nothing, treat all args as named. */
3855 /* Start updating where the next arg would go.
3857 On some machines (such as the PA) indirect calls have a different
3858 calling convention than normal calls. The fourth argument in
3859 INIT_CUMULATIVE_ARGS tells the backend if this is an indirect call
3860 or not. */
3864 /* Now possibly adjust the number of named args.
3865 Normally, don't include the last named arg if anonymous args follow.
3866 We do include the last named arg if
3867 targetm.calls.strict_argument_naming() returns nonzero.
3868 (If no anonymous args follow, the result of list_length is actually
3869 one too large. This is harmless.)
3871 If targetm.calls.pretend_outgoing_varargs_named() returns
3872 nonzero, and targetm.calls.strict_argument_naming() returns zero,
3873 this machine will be able to place unnamed args that were passed
3874 in registers into the stack. So treat all args as named. This
3875 allows the insns emitting for a specific argument list to be
3876 independent of the function declaration.
3878 If targetm.calls.pretend_outgoing_varargs_named() returns zero,
3879 we do not have any reliable way to pass unnamed args in
3880 registers, so we must force them into memory. */
3884 ;
3887 /* Don't include the last named arg. */
3889 else
3890 /* Treat all args as named. */
3893 /* Make a vector to hold all the information about each arg. */
3896 /* Build up entries in the ARGS array, compute the size of the
3897 arguments into ARGS_SIZE, etc. */
3909 /* Now make final decision about preallocating stack space. */
3914 /* If the structure value address will reference the stack pointer, we
3915 must stabilize it. We don't need to do this if we know that we are
3916 not going to adjust the stack pointer in processing this call. */
3921 structure_value_addr))
3923 || (!ACCUMULATE_OUTGOING_ARGS
3927 /* Tail calls can make things harder to debug, and we've traditionally
3928 pushed these optimizations into -O2. Don't try if we're already
3929 expanding a call, as that means we're an argument. Don't try if
3930 there's cleanups, as we know there's code to follow the call. */
3937 /* Workaround buggy C/C++ wrappers around Fortran routines with
3938 character(len=constant) arguments if the hidden string length arguments
3939 are passed on the stack; if the callers forget to pass those arguments,
3940 attempting to tail call in such routines leads to stack corruption.
3941 Avoid tail calls in functions where at least one such hidden string
3942 length argument is passed (partially or fully) on the stack in the
3943 caller and the callee needs to pass any arguments on the stack.
3944 See PR90329. */
3949 {
3953 {
3956 }
3957 }
3959 /* If the user has marked the function as requiring tail-call
3960 optimization, attempt it. */
3964 /* Rest of purposes for tail call optimizations to fail. */
3967 structure_value_addr,
3968 funtype,
3969 reg_parm_stack_space,
3970 fndecl,
3973 /* Check if caller and callee disagree in promotion of function
3974 return value. */
3976 {
3986 caller_promoted_mode
3990 callee_promoted_mode
4000 {
4003 "caller and callee disagree in"
4004 " promotion of function"
4006 }
4007 }
4009 /* Ensure current function's preferred stack boundary is at least
4010 what we need. Stack alignment may also increase preferred stack
4011 boundary. */
4020 else
4028 /* We want to make two insn chains; one for a sibling call, the other
4029 for a normal call. We will select one of the two chains after
4030 initial RTL generation is complete. */
4032 {
4034 /* We want to emit any pending stack adjustments before the tail
4035 recursion "call". That way we know any adjustment after the tail
4036 recursion call can be ignored if we indeed use the tail
4037 call expansion. */
4038 saved_pending_stack_adjust save;
4040 rtx next_arg_reg;
4043 {
4044 /* State variables we need to save and restore between
4045 iterations. */
4047 }
4050 else
4053 /* Other state variables that we must reinitialize each time
4054 through the loop (that are not initialized by the loop itself). */
4058 /* Start a new sequence for the normal call case.
4060 From this point on, if the sibling call fails, we want to set
4061 sibcall_failure instead of continuing the loop. */
4064 /* Don't let pending stack adjusts add up to too much.
4065 Also, do all pending adjustments now if there is any chance
4066 this might be a call to alloca or if we are expanding a sibling
4067 call sequence.
4068 Also do the adjustments before a throwing call, otherwise
4069 exception handling can fail; PR 19225. */
4078 /* Precompute any arguments as needed. */
4082 /* Now we are about to start emitting insns that can be deleted
4083 if a libcall is deleted. */
4093 /* Compute the actual size of the argument block required. The variable
4094 and constant sizes must be combined, the size may have to be rounded,
4095 and there may be a minimum required size. When generating a sibcall
4096 pattern, do not round up, since we'll be re-using whatever space our
4097 caller provided. */
4098 unadjusted_args_size
4107 /* The argument block when performing a sibling call is the
4108 incoming argument block. */
4110 {
4113 argblock
4115 else
4116 argblock
4123 }
4125 /* If we have no actual push instructions, or shouldn't use them,
4126 make space for all args right now. */
4128 {
4130 {
4135 /* stack_arg_under_construction says whether a stack arg is
4136 being constructed at the old stack level. Pushing the stack
4137 gets a clean outgoing argument block. */
4140 }
4144 }
4145 else
4146 {
4147 /* Note that we must go through the motions of allocating an argument
4148 block even if the size is zero because we may be storing args
4149 in the area reserved for register arguments, which may be part of
4150 the stack frame. */
4154 /* Store the maximum argument space used. It will be pushed by
4155 the prologue (if ACCUMULATE_OUTGOING_ARGS, or stack overflow
4156 checking). */
4159 needed);
4162 {
4164 {
4165 /* Since the stack pointer will never be pushed, it is
4166 possible for the evaluation of a parm to clobber
4167 something we have already written to the stack.
4168 Since most function calls on RISC machines do not use
4169 the stack, this is uncommon, but must work correctly.
4171 Therefore, we save any area of the stack that was already
4172 written and that we are using. Here we set up to do this
4173 by making a new stack usage map from the old one. The
4174 actual save will be done by store_one_arg.
4176 Another approach might be to try to reorder the argument
4177 evaluations to avoid this conflicting stack usage. */
4179 /* Since we will be writing into the entire argument area,
4180 the map must be allocated for its entire size, not just
4181 the part that is the responsibility of the caller. */
4189 /* For polynomial sizes, this is the maximum possible
4190 size needed for arguments with a constant size
4191 and offset. */
4193 highest_outgoing_arg_in_use
4202 initial_highest_arg_in_use);
4206 (highest_outgoing_arg_in_use
4210 /* The address of the outgoing argument list must not be
4211 copied to a register here, because argblock would be left
4212 pointing to the wrong place after the call to
4213 allocate_dynamic_stack_space below. */
4216 }
4217 else
4218 {
4219 /* Try to reuse some or all of the pending_stack_adjust
4220 to get this space. */
4222 && (combine_pending_stack_adjustment_and_call
4224 unadjusted_args_size,
4226 preferred_unit_stack_boundary)))
4227 {
4228 /* combine_pending_stack_adjustment_and_call computes
4229 an adjustment before the arguments are allocated.
4230 Account for them and see whether or not the stack
4231 needs to go up or down. */
4234 /* Checked by
4235 combine_pending_stack_adjustment_and_call. */
4238 {
4239 /* We're releasing stack space. */
4240 /* ??? We can avoid any adjustment at all if we're
4241 already aligned. FIXME. */
4245 }
4246 else
4247 /* We need to allocate space. We'll do that in
4248 push_block below. */
4250 }
4252 /* Special case this because overhead of `push_block' in
4253 this case is non-trivial. */
4256 else
4257 {
4262 }
4264 /* We only really need to call `copy_to_reg' in the case
4265 where push insns are going to be used to pass ARGBLOCK
4266 to a function call in ARGS. In that case, the stack
4267 pointer changes value from the allocation point to the
4268 call point, and hence the value of
4269 VIRTUAL_OUTGOING_ARGS_RTX changes as well. But might
4270 as well always do it. */
4272 }
4273 }
4274 }
4277 {
4278 /* The save/restore code in store_one_arg handles all
4279 cases except one: a constructor call (including a C
4280 function returning a BLKmode struct) to initialize
4281 an argument. */
4283 {
4284 rtx push_size
4285 = (gen_int_mode
4291 {
4296 /* stack_arg_under_construction says whether a stack
4297 arg is being constructed at the old stack level.
4298 Pushing the stack gets a clean outgoing argument
4299 block. */
4300 old_stack_arg_under_construction
4303 /* Make a new map for the new argument list. */
4309 }
4310 /* We can pass TRUE as the 4th argument because we just
4311 saved the stack pointer and will restore it right after
4312 the call. */
4315 }
4317 /* If argument evaluation might modify the stack pointer,
4318 copy the address of the argument list to a register. */
4321 {
4324 }
4325 }
4329 /* Stack is properly aligned, pops can't safely be deferred during
4330 the evaluation of the arguments. */
4331 NO_DEFER_POP;
4333 /* Precompute all register parameters. It isn't safe to compute
4334 anything once we have started filling any specific hard regs.
4335 TLS symbols sometimes need a call to resolve. Precompute
4336 register parameters before any stack pointer manipulation
4337 to avoid unaligned stack in the called function. */
4340 OK_DEFER_POP;
4342 /* Perform stack alignment before the first push (the last arg). */
4346 {
4347 /* When the stack adjustment is pending, we get better code
4348 by combining the adjustments. */
4350 && ! inhibit_defer_pop
4351 && (combine_pending_stack_adjustment_and_call
4353 unadjusted_args_size,
4355 preferred_unit_stack_boundary)))
4360 Pmode));
4361 }
4362 /* Now that the stack is properly aligned, pops can't safely
4363 be deferred during the evaluation of the arguments. */
4364 NO_DEFER_POP;
4366 /* Record the maximum pushed stack space size. We need to delay
4367 doing it this far to take into account the optimization done
4368 by combine_pending_stack_adjustment_and_call. */
4370 && !ACCUMULATE_OUTGOING_ARGS
4371 && pass
4373 {
4376 current_function_pushed_stack_size
4378 }
4384 else
4387 #ifdef REG_PARM_STACK_SPACE
4388 /* Save the fixed argument area if it's part of the caller's frame and
4389 is clobbered by argument setup for this call. */
4393 #endif
4395 /* Now store (and compute if necessary) all non-register parms.
4396 These come before register parms, since they can require block-moves,
4397 which could clobber the registers used for register parms.
4398 Parms which have partial registers are not stored here,
4399 but we do preallocate space here if they want that. */
4402 {
4404 {
4407 /* We don't allow passing huge (> 2^30 B) arguments
4408 by value. It would cause an overflow later on. */
4411 {
4414 }
4418 reg_parm_stack_space)
4423 }
4426 call_fusage
4429 call_fusage);
4430 }
4432 /* If we have a parm that is passed in registers but not in memory
4433 and whose alignment does not permit a direct copy into registers,
4434 make a group of pseudos that correspond to each register that we
4435 will later fill. */
4439 /* Now store any partially-in-registers parm.
4440 This is the last place a block-move can happen. */
4444 {
4447 /* On targets with weird calling conventions (e.g. PA) it's
4448 hard to ensure that all cases of argument overlap between
4449 stack and registers work. Play it safe and bail out. */
4451 {
4454 }
4458 reg_parm_stack_space)
4463 }
4468 {
4471 }
4475 /* Figure out the register where the value, if any, will come back. */
4479 {
4483 else
4487 /* If VALREG is a PARALLEL whose first member has a zero
4488 offset, use that. This is for targets such as m68k that
4489 return the same value in multiple places. */
4491 {
4498 }
4499 }
4501 /* If register arguments require space on the stack and stack space
4502 was not preallocated, allocate stack space here for arguments
4503 passed in registers. */
4505 && !ACCUMULATE_OUTGOING_ARGS
4509 /* Pass the function the address in which to return a
4510 structure value. */
4512 {
4513 structure_value_addr
4518 NULL_RTX)));
4522 }
4532 /* Save a pointer to the last insn before the call, so that we can
4533 later safely search backwards to find the CALL_INSN. */
4536 /* Set up next argument register. For sibling calls on machines
4537 with register windows this should be the incoming register. */
4541 else
4546 {
4552 && valreg
4555 call_fusage
4558 call_fusage);
4559 }
4560 /* All arguments and registers used for the call must be set up by
4561 now! */
4563 /* Stack must be properly aligned now. */
4566 preferred_unit_stack_boundary));
4568 /* Generate the actual call instruction. */
4575 {
4579 {
4583 }
4586 }
4588 /* If the call setup or the call itself overlaps with anything
4589 of the argument setup we probably clobbered our call address.
4590 In that case we can't do sibcalls. */
4595 /* If a non-BLKmode value is returned at the most significant end
4596 of a register, shift the register right by the appropriate amount
4597 and update VALREG accordingly. BLKmode values are handled by the
4598 group load/store machinery below. */
4600 && !pcc_struct_value
4605 {
4609 }
4612 {
4616 /* The return value from a malloc-like function is a pointer. */
4622 /* The return value from a malloc-like function cannot alias
4623 anything else. */
4627 /* Write out the sequence. */
4632 }
4634 /* For calls to `setjmp', etc., inform
4635 function.c:setjmp_warnings that it should complain if
4636 nonvolatile values are live. For functions that cannot
4637 return, inform flow that control does not fall through. */
4640 {
4641 /* The barrier must be emitted
4642 immediately after the CALL_INSN. Some ports emit more
4643 than just a CALL_INSN above, so we must search for it here. */
4647 {
4649 /* There was no CALL_INSN? */
4651 }
4655 /* Stack adjustments after a noreturn call are dead code.
4656 However when NO_DEFER_POP is in effect, we must preserve
4657 stack_pointer_delta. */
4659 {
4662 }
4663 }
4665 /* If value type not void, return an rtx for the value. */
4671 {
4673 {
4674 target
4677 structure_value_addr));
4679 }
4680 }
4682 {
4683 /* This is the special C++ case where we need to
4684 know what the true target was. We take care to
4685 never use this value more than once in one expression. */
4689 }
4690 /* Handle calls that return values in multiple non-contiguous locations.
4691 The Irix 6 ABI has examples of this. */
4693 {
4697 ;
4699 /* Handle the result of a emit_group_move_into_temps
4700 call in the previous pass. */
4702 else
4705 }
4709 {
4712 /* We have to copy a return value in a CLASS_LIKELY_SPILLED hard
4713 reg to a plain register. */
4717 /* If TARGET is a MEM in the argument area, and we have
4718 saved part of the argument area, then we can't store
4719 directly into TARGET as it may get overwritten when we
4720 restore the argument save area below. Don't work too
4721 hard though and simply force TARGET to a register if it
4722 is a MEM; the optimizer is quite likely to sort it out. */
4726 {
4729 }
4733 else
4734 {
4735 /* TARGET and VALREG cannot be equal at this point
4736 because the latter would not have
4737 REG_FUNCTION_VALUE_P true, while the former would if
4738 it were referring to the same register.
4740 If they refer to the same register, this move will be
4741 a no-op, except when function inlining is being
4742 done. */
4745 /* If we are setting a MEM, this code must be executed.
4746 Since it is emitted after the call insn, sibcall
4747 optimization cannot be performed in that case. */
4750 }
4751 }
4752 else
4755 /* If we promoted this return value, make the proper SUBREG.
4756 TARGET might be const0_rtx here, so be careful. */
4760 {
4763 machine_mode pmode;
4765 /* Ensure we promote as expected, and get the new unsignedness. */
4775 }
4777 /* If size of args is variable or this was a constructor call for a stack
4778 argument, restore saved stack-pointer value. */
4781 {
4796 }
4798 {
4799 #ifdef REG_PARM_STACK_SPACE
4803 #endif
4805 /* If we saved any argument areas, restore them. */
4808 {
4810 rtx stack_area
4817 else
4819 (gen_int_mode
4821 BLOCK_OP_CALL_PARM);
4822 }
4827 }
4829 /* If this was alloca, record the new stack level. */
4833 /* Free up storage we no longer need. */
4843 {
4846 /* Restore the pending stack adjustment now that we have
4847 finished generating the sibling call sequence. */
4851 /* Prepare arg structure for next iteration. */
4853 {
4857 }
4862 }
4863 else
4864 {
4867 /* Verify that we've deallocated all the stack we used. */
4870 stack_pointer_delta
4872 }
4874 /* If something prevents making this a sibling call,
4875 zero out the sequence. */
4878 else
4880 }
4882 /* If tail call production succeeded, we need to remove REG_EQUIV notes on
4883 arguments too, as argument area is now clobbered by the call. */
4885 {
4888 }
4889 else
4890 {
4893 /* Ideally we'd emit a message for all of the ways that it could
4894 have failed. */
4896 }
4898 currently_expanding_call--;
4903 }
4905 /* A sibling call sequence invalidates any REG_EQUIV notes made for
4906 this function's incoming arguments.
4908 At the start of RTL generation we know the only REG_EQUIV notes
4909 in the rtl chain are those for incoming arguments, so we can look
4910 for REG_EQUIV notes between the start of the function and the
4911 NOTE_INSN_FUNCTION_BEG.
4913 This is (slight) overkill. We could keep track of the highest
4914 argument we clobber and be more selective in removing notes, but it
4915 does not seem to be worth the effort. */
4917 void
4919 {
4923 {
4924 rtx note;
4926 /* There are never REG_EQUIV notes for the incoming arguments
4927 after the NOTE_INSN_FUNCTION_BEG note, so stop if we see it. */
4937 }
4938 }
4940 /* Traverse a list of TYPES and expand all complex types into their
4941 components. */
4942 static tree
4944 {
4945 tree p;
4947 /* Before allocating memory, check for the common case of no complex. */
4949 {
4954 }
4957 found:
4961 {
4966 {
4969 /* Rewrite complex type with component type. */
4973 /* Add another component type for the imaginary part. */
4978 /* Skip the newly created node. */
4980 }
4981 }
4984 }
4985 \f
4986 /* Output a library call to function ORGFUN (a SYMBOL_REF rtx)
4987 for a value of mode OUTMODE,
4988 with NARGS different arguments, passed as ARGS.
4989 Store the return value if RETVAL is nonzero: store it in VALUE if
4990 VALUE is nonnull, otherwise pick a convenient location. In either
4991 case return the location of the stored value.
4993 FN_TYPE should be LCT_NORMAL for `normal' calls, LCT_CONST for
4994 `const' calls, LCT_PURE for `pure' calls, or another LCT_ value for
4995 other types of library calls. */
4997 rtx
5001 {
5002 /* Total size in bytes of all the stack-parms scanned so far. */
5004 /* Size of arguments before any adjustments (such as rounding). */
5007 rtx fun;
5008 /* Todo, choose the correct decl type of orgfun. Sadly this information
5009 isn't present here, so we default to native calling abi here. */
5014 CUMULATIVE_ARGS args_so_far_v;
5015 cumulative_args_t args_so_far;
5016 struct arg
5017 {
5018 rtx value;
5019 machine_mode mode;
5020 rtx reg;
5023 rtx save_area;
5024 };
5029 rtx valreg;
5034 poly_int64 needed;
5039 #ifdef REG_PARM_STACK_SPACE
5040 /* Define the boundary of the register parm stack space that needs to be
5041 save, if any. */
5044 #endif
5046 /* Size of the stack reserved for parameter registers. */
5054 #ifdef REG_PARM_STACK_SPACE
5056 #endif
5058 /* By default, library functions cannot throw. */
5062 {
5080 }
5083 /* Ensure current function's preferred stack boundary is at least
5084 what we need. */
5088 /* If this kind of value comes back in memory,
5089 decide where in memory it should come back. */
5091 {
5094 {
5095 #ifdef PCC_STATIC_STRUCT_RETURN
5096 rtx pointer_reg
5106 else
5108 #endif
5109 /* This call returns a big structure. */
5111 }
5112 }
5113 else
5116 /* ??? Unfinished: must pass the memory address as an argument. */
5118 /* Copy all the libcall-arguments out of the varargs data
5119 and into a vector ARGVEC.
5121 Compute how to pass each argument. We only support a very small subset
5122 of the full argument passing conventions to limit complexity here since
5123 library functions shouldn't have many args. */
5128 #ifdef INIT_CUMULATIVE_LIBCALL_ARGS
5130 #else
5132 #endif
5142 /* If there's a structure value address to be passed,
5143 either pass it in the special place, or pass it as an extra argument. */
5145 {
5148 nargs++;
5150 /* Make sure it is a reasonable operand for a move or push insn. */
5165 #ifdef STACK_PARMS_IN_REG_PARM_AREA
5167 #else
5169 #endif
5179 count++;
5180 }
5183 {
5188 /* We cannot convert the arg value to the mode the library wants here;
5189 must do it earlier where we know the signedness of the arg. */
5194 /* Make sure it is a reasonable operand for a move or push insn. */
5201 {
5202 rtx slot;
5205 /* If this was a CONST function, it is now PURE since it now
5206 reads memory. */
5208 {
5211 }
5214 {
5219 }
5220 else
5221 {
5225 }
5229 call_fusage);
5233 slot),
5234 call_fusage);
5239 }
5245 unsigned_p);
5254 {
5256 #ifdef STACK_PARMS_IN_REG_PARM_AREA
5258 #else
5260 #endif
5265 }
5266 #ifdef BLOCK_REG_PADDING
5267 else
5268 /* The argument is passed entirely in registers. See at which
5269 end it should be padded. */
5273 UNITS_PER_WORD));
5274 #endif
5277 }
5285 /* If this machine requires an external definition for library
5286 functions, write one out. */
5292 STACK_BYTES)
5296 reg_parm_stack_space);
5305 {
5307 current_function_pushed_stack_size
5309 }
5312 {
5313 /* Since the stack pointer will never be pushed, it is possible for
5314 the evaluation of a parm to clobber something we have already
5315 written to the stack. Since most function calls on RISC machines
5316 do not use the stack, this is uncommon, but must work correctly.
5318 Therefore, we save any area of the stack that was already written
5319 and that we are using. Here we set up to do this by making a new
5320 stack usage map from the old one.
5322 Another approach might be to try to reorder the argument
5323 evaluations to avoid this conflicting stack usage. */
5327 /* Since we will be writing into the entire argument area, the
5328 map must be allocated for its entire size, not just the part that
5329 is the responsibility of the caller. */
5337 /* For polynomial sizes, this is the maximum possible size needed
5338 for arguments with a constant size and offset. */
5341 const_limit);
5348 initial_highest_arg_in_use);
5355 /* We must be careful to use virtual regs before they're instantiated,
5356 and real regs afterwards. Loop optimization, for example, can create
5357 new libcalls after we've instantiated the virtual regs, and if we
5358 use virtuals anyway, they won't match the rtl patterns. */
5362 STACK_POINTER_OFFSET);
5363 else
5365 }
5366 else
5367 {
5370 }
5372 /* We push args individually in reverse order, perform stack alignment
5373 before the first push (the last arg). */
5377 Pmode));
5381 #ifdef REG_PARM_STACK_SPACE
5383 {
5384 /* The argument list is the property of the called routine and it
5385 may clobber it. If the fixed area has been used for previous
5386 parameters, we must save and restore it. */
5389 }
5390 #endif
5392 /* When expanding a normal call, args are stored in push order,
5393 which is the reverse of what we have here. */
5397 {
5400 }
5404 /* Push the args that need to be pushed. */
5408 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
5409 are to be pushed. */
5411 {
5420 {
5421 rtx use;
5424 {
5425 /* If this is being stored into a pre-allocated, fixed-size,
5426 stack area, save any previous data at that location. */
5429 {
5430 /* stack_slot is negative, but we want to index stack_usage_map
5431 with positive values. */
5434 }
5435 else
5436 {
5439 }
5442 reg_parm_stack_space))
5443 {
5444 /* We need to make a save area. */
5445 poly_uint64 size
5447 machine_mode save_mode
5449 rtx adr
5452 rtx stack_area
5456 {
5460 );
5464 stack_area,
5465 (gen_int_mode
5467 Pmode)),
5468 BLOCK_OP_CALL_PARM);
5469 }
5470 else
5471 {
5475 }
5476 }
5477 }
5481 (gen_int_mode
5483 reg_parm_stack_space,
5486 /* Now mark the segment we just used. */
5490 NO_DEFER_POP;
5492 /* Indicate argument access so that alias.c knows that these
5493 values are live. */
5499 else
5500 {
5501 /* When arguments are pushed, trying to tell alias.c where
5502 exactly this argument is won't work, because the
5503 auto-increment causes confusion. So we merely indicate
5504 that we access something with a known mode somewhere on
5505 the stack. */
5509 }
5513 }
5514 }
5520 /* Now load any reg parms into their regs. */
5522 /* ARGNUM indexes the ARGVEC array in the order in which the arguments
5523 are to be pushed. */
5525 {
5531 /* Handle calls that pass values in multiple non-contiguous
5532 locations. The PA64 has examples of this for library calls. */
5536 {
5538 #ifdef BLOCK_REG_PADDING
5541 /* Copied from load_register_parameters. */
5543 /* Handle case where we have a value that needs shifting
5544 up to the msb. eg. a QImode value and we're padding
5545 upward on a BYTES_BIG_ENDIAN machine. */
5549 {
5550 rtx x;
5553 /* Assigning REG here rather than a temp makes CALL_FUSAGE
5554 report the whole reg as used. Strictly speaking, the
5555 call only uses SIZE bytes at the msb end, but it doesn't
5556 seem worth generating rtl to say that. */
5561 }
5562 #endif
5563 }
5565 NO_DEFER_POP;
5566 }
5568 /* Any regs containing parms remain in use through the call. */
5570 {
5575 {
5578 {
5583 }
5584 else
5586 }
5587 }
5589 /* Pass the function the address in which to return a structure value. */
5591 {
5595 NULL_RTX)));
5598 }
5600 /* Don't allow popping to be deferred, since then
5601 cse'ing of library calls could delete a call and leave the pop. */
5602 NO_DEFER_POP;
5606 /* Stack must be properly aligned now. */
5615 /* We pass the old value of inhibit_defer_pop + 1 to emit_call_1, which
5616 will set inhibit_defer_pop to that value. */
5617 /* The return type is needed to decide how many bytes the function pops.
5618 Signedness plays no role in that, so for simplicity, we pretend it's
5619 always signed. We also assume that the list of arguments passed has
5620 no impact, so we pretend it is unknown. */
5626 struct_value_size,
5629 valreg,
5633 {
5638 }
5640 /* Right-shift returned value if necessary. */
5644 {
5647 }
5651 /* For calls to `setjmp', etc., inform function.c:setjmp_warnings
5652 that it should complain if nonvolatile values are live. For
5653 functions that cannot return, inform flow that control does not
5654 fall through. */
5656 {
5657 /* The barrier note must be emitted
5658 immediately after the CALL_INSN. Some ports emit more than
5659 just a CALL_INSN above, so we must search for it here. */
5662 {
5664 /* There was no CALL_INSN? */
5666 }
5669 }
5671 /* Consider that "regular" libcalls, i.e. all of them except for LCT_THROW
5672 and LCT_RETURNS_TWICE, cannot perform non-local gotos. */
5674 {
5677 {
5679 /* There was no CALL_INSN? */
5681 }
5684 }
5686 /* Now restore inhibit_defer_pop to its actual original value. */
5687 OK_DEFER_POP;
5691 /* Copy the value to the right place. */
5693 {
5695 {
5700 }
5702 {
5706 }
5707 else
5708 {
5709 /* Convert to the proper mode if a promotion has been active. */
5711 {
5718 }
5722 else
5724 }
5725 }
5728 {
5729 #ifdef REG_PARM_STACK_SPACE
5733 #endif
5735 /* If we saved any argument areas, restore them. */
5738 {
5747 validize_mem
5749 (gen_int_mode
5751 BLOCK_OP_CALL_PARM);
5752 else
5754 }
5759 }
5765 }
5766 \f
5768 /* Store a single argument for a function call
5769 into the register or memory area where it must be passed.
5770 *ARG describes the argument value and where to pass it.
5772 ARGBLOCK is the address of the stack-block for all the arguments,
5773 or 0 on a machine where arguments are pushed individually.
5775 MAY_BE_ALLOCA nonzero says this could be a call to `alloca'
5776 so must be careful about how the stack is used.
5778 VARIABLE_SIZE nonzero says that this was a variable-sized outgoing
5779 argument stack. This is used if ACCUMULATE_OUTGOING_ARGS to indicate
5780 that we need not worry about saving and restoring the stack.
5782 FNDECL is the declaration of the function we are calling.
5784 Return nonzero if this arg should cause sibcall failure,
5785 zero otherwise. */
5787 static int
5790 {
5801 /* Push a new temporary level for any temporaries we make for
5802 this argument. */
5806 {
5807 /* If this is being stored into a pre-allocated, fixed-size, stack area,
5808 save any previous data at that location. */
5810 {
5812 {
5813 /* stack_slot is negative, but we want to index stack_usage_map
5814 with positive values. */
5816 {
5819 }
5820 else
5824 }
5825 else
5826 {
5828 {
5831 }
5832 else
5836 }
5839 reg_parm_stack_space))
5840 {
5841 /* We need to make a save area. */
5843 machine_mode save_mode
5849 {
5850 arg->save_area
5854 stack_area,
5855 (gen_int_mode
5857 BLOCK_OP_CALL_PARM);
5858 }
5859 else
5860 {
5863 }
5864 }
5865 }
5866 }
5868 /* If this isn't going to be placed on both the stack and in registers,
5869 set up the register and number of words. */
5871 {
5874 else
5877 }
5879 /* Being passed entirely in a register. We shouldn't be called in
5880 this case. */
5883 /* If this arg needs special alignment, don't load the registers
5884 here. */
5888 /* If this is being passed partially in a register, we can't evaluate
5889 it directly into its stack slot. Otherwise, we can. */
5891 {
5892 /* stack_arg_under_construction is nonzero if a function argument is
5893 being evaluated directly into the outgoing argument list and
5894 expand_call must take special action to preserve the argument list
5895 if it is called recursively.
5897 For scalar function arguments stack_usage_map is sufficient to
5898 determine which stack slots must be saved and restored. Scalar
5899 arguments in general have pass_on_stack == 0.
5901 If this argument is initialized by a function which takes the
5902 address of the argument (a C++ constructor or a C function
5903 returning a BLKmode structure), then stack_usage_map is
5904 insufficient and expand_call must push the stack around the
5905 function call. Such arguments have pass_on_stack == 1.
5907 Note that it is always safe to set stack_arg_under_construction,
5908 but this generates suboptimal code if set when not needed. */
5911 stack_arg_under_construction++;
5914 (partial
5919 /* If we are promoting object (or for any other reason) the mode
5920 doesn't agree, convert the mode. */
5927 stack_arg_under_construction--;
5928 }
5930 /* Check for overlap with already clobbered argument area. */
5937 /* Don't allow anything left on stack from computation
5938 of argument to alloca. */
5943 /* If the value is already in the stack slot, we are done. */
5944 ;
5946 {
5949 /* Argument is a scalar, not entirely passed in registers.
5950 (If part is passed in registers, arg->partial says how much
5951 and emit_push_insn will take care of putting it there.)
5953 Push it, and if its size is less than the
5954 amount of space allocated to it,
5955 also bump stack pointer by the additional space.
5956 Note that in C the default argument promotions
5957 will prevent such mismatches. */
5962 /* Compute how much space the push instruction will push.
5963 On many machines, pushing a byte will advance the stack
5964 pointer by a halfword. */
5965 #ifdef PUSH_ROUNDING
5967 #endif
5970 /* Compute how much space the argument should get:
5971 round up to a multiple of the alignment for arguments. */
5974 /* At the moment we don't (need to) support ABIs for which the
5975 padding isn't known at compile time. In principle it should
5976 be easy to add though. */
5979 /* Compute the alignment of the pushed argument. */
5983 {
5988 }
5990 /* This isn't already where we want it on the stack, so put it there.
5991 This can either be done with push or copy insns. */
5996 reg_parm_stack_space,
6000 /* Unless this is a partially-in-register argument, the argument is now
6001 in the stack. */
6004 }
6005 else
6006 {
6007 /* BLKmode, at least partly to be pushed. */
6010 poly_int64 excess;
6011 rtx size_rtx;
6013 /* Pushing a nonscalar.
6014 If part is passed in registers, PARTIAL says how much
6015 and emit_push_insn will take care of putting it there. */
6017 /* Round its size up to a multiple
6018 of the allocation unit for arguments. */
6021 {
6024 }
6025 else
6026 {
6027 /* PUSH_ROUNDING has no effect on us, because emit_push_insn
6028 for BLKmode is careful to avoid it. */
6034 EXPAND_NORMAL);
6035 }
6039 /* When an argument is padded down, the block is aligned to
6040 PARM_BOUNDARY, but the actual argument isn't. */
6043 {
6046 else
6047 {
6048 unsigned int excess_align
6052 }
6053 }
6056 {
6057 /* emit_push_insn might not work properly if arg->value and
6058 argblock + arg->locate.offset areas overlap. */
6064 {
6065 /* arg.locate doesn't contain the pretend_args_size offset,
6066 it's part of argblock. Ensure we don't count it in I. */
6069 else
6072 /* expand_call should ensure this. */
6078 {
6079 /* Even though they appear to be at the same location,
6080 if part of the outgoing argument is in registers,
6081 they aren't really at the same location. Check for
6082 this by making sure that the incoming size is the
6083 same as the outgoing size. */
6086 }
6090 /* Use arg->locate.size.constant instead of size_rtx
6091 because we only care about the part of the argument
6092 on the stack. */
6096 }
6097 }
6103 reg_parm_stack_space,
6106 /* Unless this is a partially-in-register argument, the argument is now
6107 in the stack.
6109 ??? Unlike the case above, in which we want the actual
6110 address of the data, so that we can load it directly into a
6111 register, here we want the address of the stack slot, so that
6112 it's properly aligned for word-by-word copying or something
6113 like that. It's not clear that this is always correct. */
6116 }
6119 {
6121 arg->parallel_value
6124 }
6126 /* Mark all slots this store used. */
6131 /* Once we have pushed something, pops can't safely
6132 be deferred during the rest of the arguments. */
6133 NO_DEFER_POP;
6135 /* Free any temporary slots made in processing this argument. */
6139 }
6141 /* Nonzero if we do not know how to pass ARG solely in registers. */
6143 bool
6145 {
6149 /* If the type has variable size... */
6153 /* If the type is marked as addressable (it is required
6154 to be constructed into the stack)... */
6159 }
6161 /* Another version of the TARGET_MUST_PASS_IN_STACK hook. This one
6162 takes trailing padding of a structure into account. */
6163 /* ??? Should be able to merge these two by examining BLOCK_REG_PADDING. */
6165 bool
6167 {
6171 /* If the type has variable size... */
6175 /* If the type is marked as addressable (it is required
6176 to be constructed into the stack)... */
6183 /* If the padding and mode of the type is such that a copy into
6184 a register would put it into the wrong part of the register. */
6192 }
6194 /* Return true if TYPE must be passed on the stack when passed to
6195 the "..." arguments of a function. */
6197 bool
6199 {
6202 }
6204 /* Return true if FIELD is the C++17 empty base field that should
6205 be ignored for ABI calling convention decisions in order to
6206 maintain ABI compatibility between C++14 and earlier, which doesn't
6207 add this FIELD to classes with empty bases, and C++17 and later
6208 which does. */
6210 bool
6212 {
6217 }
6219 /* Tell the garbage collector about GTY markers in this source file. */