1 /****************************************************************************
3 * GNAT COMPILER COMPONENTS *
7 * C Implementation File *
9 * Copyright (C) 1992-2004 Free Software Foundation, Inc. *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 2, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License distributed with GNAT; see file COPYING. If not, write *
19 * to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, *
20 * MA 02111-1307, USA. *
22 * As a special exception, if you link this file with other files to *
23 * produce an executable, this file does not by itself cause the resulting *
24 * executable to be covered by the GNU General Public License. This except- *
25 * ion does not however invalidate any other reasons why the executable *
26 * file might be covered by the GNU Public License. *
28 * GNAT was originally developed by the GNAT team at New York University. *
29 * Extensive contributions were provided by Ada Core Technologies Inc. *
31 ****************************************************************************/
33 /* This file contains parts of the compiler that are required for interfacing
34 with GCC but otherwise do nothing and parts of Gigi that need to know
39 #include "coretypes.h"
45 #include "diagnostic.h"
52 #include "tree-inline.h"
53 #include "insn-codes.h"
54 #include "insn-flags.h"
55 #include "insn-config.h"
62 #include "langhooks.h"
63 #include "langhooks-def.h"
79 #include "adadecode.h"
83 extern FILE *asm_out_file;
85 /* The largest alignment, in bits, that is needed for using the widest
87 unsigned int largest_move_alignment;
89 static bool gnat_init (void);
90 static void gnat_finish_incomplete_decl (tree);
91 static unsigned int gnat_init_options (unsigned int, const char **);
92 static int gnat_handle_option (size_t, const char *, int);
93 static bool gnat_post_options (const char **);
94 static HOST_WIDE_INT gnat_get_alias_set (tree);
95 static void gnat_print_decl (FILE *, tree, int);
96 static void gnat_print_type (FILE *, tree, int);
97 static const char *gnat_printable_name (tree, int);
98 static tree gnat_eh_runtime_type (tree);
99 static int gnat_eh_type_covers (tree, tree);
100 static void gnat_parse_file (int);
101 static rtx gnat_expand_expr (tree, rtx, enum machine_mode, int,
103 static void internal_error_function (const char *, va_list *);
104 static void gnat_adjust_rli (record_layout_info);
106 /* Definitions for our language-specific hooks. */
108 #undef LANG_HOOKS_NAME
109 #define LANG_HOOKS_NAME "GNU Ada"
110 #undef LANG_HOOKS_IDENTIFIER_SIZE
111 #define LANG_HOOKS_IDENTIFIER_SIZE sizeof (struct tree_identifier)
112 #undef LANG_HOOKS_INIT
113 #define LANG_HOOKS_INIT gnat_init
114 #undef LANG_HOOKS_INIT_OPTIONS
115 #define LANG_HOOKS_INIT_OPTIONS gnat_init_options
116 #undef LANG_HOOKS_HANDLE_OPTION
117 #define LANG_HOOKS_HANDLE_OPTION gnat_handle_option
118 #undef LANG_HOOKS_POST_OPTIONS
119 #define LANG_HOOKS_POST_OPTIONS gnat_post_options
120 #undef LANG_HOOKS_PARSE_FILE
121 #define LANG_HOOKS_PARSE_FILE gnat_parse_file
122 #undef LANG_HOOKS_HONOR_READONLY
123 #define LANG_HOOKS_HONOR_READONLY true
124 #undef LANG_HOOKS_HASH_TYPES
125 #define LANG_HOOKS_HASH_TYPES false
126 #undef LANG_HOOKS_GETDECLS
127 #define LANG_HOOKS_GETDECLS lhd_return_null_tree_v
128 #undef LANG_HOOKS_PUSHDECL
129 #define LANG_HOOKS_PUSHDECL lhd_return_tree
130 #undef LANG_HOOKS_FINISH_INCOMPLETE_DECL
131 #define LANG_HOOKS_FINISH_INCOMPLETE_DECL gnat_finish_incomplete_decl
132 #undef LANG_HOOKS_GET_ALIAS_SET
133 #define LANG_HOOKS_GET_ALIAS_SET gnat_get_alias_set
134 #undef LANG_HOOKS_EXPAND_EXPR
135 #define LANG_HOOKS_EXPAND_EXPR gnat_expand_expr
136 #undef LANG_HOOKS_MARK_ADDRESSABLE
137 #define LANG_HOOKS_MARK_ADDRESSABLE gnat_mark_addressable
138 #undef LANG_HOOKS_TRUTHVALUE_CONVERSION
139 #define LANG_HOOKS_TRUTHVALUE_CONVERSION gnat_truthvalue_conversion
140 #undef LANG_HOOKS_PRINT_DECL
141 #define LANG_HOOKS_PRINT_DECL gnat_print_decl
142 #undef LANG_HOOKS_PRINT_TYPE
143 #define LANG_HOOKS_PRINT_TYPE gnat_print_type
144 #undef LANG_HOOKS_DECL_PRINTABLE_NAME
145 #define LANG_HOOKS_DECL_PRINTABLE_NAME gnat_printable_name
146 #undef LANG_HOOKS_CALLGRAPH_EXPAND_FUNCTION
147 #define LANG_HOOKS_CALLGRAPH_EXPAND_FUNCTION gnat_expand_body
148 #undef LANG_HOOKS_RTL_EXPAND_STMT
149 #define LANG_HOOKS_RTL_EXPAND_STMT gnat_expand_stmt
150 #undef LANG_HOOKS_GIMPLIFY_EXPR
151 #define LANG_HOOKS_GIMPLIFY_EXPR gnat_gimplify_expr
153 #undef LANG_HOOKS_TYPE_FOR_MODE
154 #define LANG_HOOKS_TYPE_FOR_MODE gnat_type_for_mode
155 #undef LANG_HOOKS_TYPE_FOR_SIZE
156 #define LANG_HOOKS_TYPE_FOR_SIZE gnat_type_for_size
157 #undef LANG_HOOKS_SIGNED_TYPE
158 #define LANG_HOOKS_SIGNED_TYPE gnat_signed_type
159 #undef LANG_HOOKS_UNSIGNED_TYPE
160 #define LANG_HOOKS_UNSIGNED_TYPE gnat_unsigned_type
161 #undef LANG_HOOKS_SIGNED_OR_UNSIGNED_TYPE
162 #define LANG_HOOKS_SIGNED_OR_UNSIGNED_TYPE gnat_signed_or_unsigned_type
164 const struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
166 /* Tables describing GCC tree codes used only by GNAT.
168 Table indexed by tree code giving a string containing a character
169 classifying the tree code. Possibilities are
170 t, d, s, c, r, <, 1 and 2. See cp-tree.def for details. */
172 #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE,
174 const char tree_code_type[] = {
177 #include "ada-tree.def"
181 /* Table indexed by tree code giving number of expression
182 operands beyond the fixed part of the node structure.
183 Not used for types or decls. */
185 #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH,
187 const unsigned char tree_code_length[] = {
190 #include "ada-tree.def"
194 /* Names of tree components.
195 Used for printing out the tree and error messages. */
196 #define DEFTREECODE(SYM, NAME, TYPE, LEN) NAME,
198 const char *const tree_code_name[] = {
201 #include "ada-tree.def"
205 /* Command-line argc and argv.
206 These variables are global, since they are imported and used in
209 unsigned int save_argc;
210 const char **save_argv;
212 /* gnat standard argc argv */
214 extern int gnat_argc;
215 extern char **gnat_argv;
218 /* Declare functions we use as part of startup. */
219 extern void __gnat_initialize (void);
220 extern void adainit (void);
221 extern void _ada_gnat1drv (void);
223 /* The parser for the language. For us, we process the GNAT tree. */
226 gnat_parse_file (int set_yydebug ATTRIBUTE_UNUSED)
228 /* call the target specific initializations */
231 /* Call the front-end elaboration procedures */
234 /* Call the front end */
237 cgraph_finalize_compilation_unit ();
241 /* Decode all the language specific options that cannot be decoded by GCC.
242 The option decoding phase of GCC calls this routine on the flags that
243 it cannot decode. This routine returns the number of consecutive arguments
244 from ARGV that it successfully decoded; 0 indicates failure. */
247 gnat_handle_option (size_t scode, const char *arg, int value ATTRIBUTE_UNUSED)
249 const struct cl_option *option = &cl_options[scode];
250 enum opt_code code = (enum opt_code) scode;
254 if (arg == NULL && (option->flags & (CL_JOINED | CL_SEPARATE)))
256 error ("missing argument to \"-%s\"", option->opt_text);
266 q = xmalloc (sizeof("-I") + strlen (arg));
269 gnat_argv[gnat_argc] = q;
273 /* All front ends are expected to accept this. */
275 /* These are used in the GCC Makefile. */
276 case OPT_Wmissing_prototypes:
277 case OPT_Wstrict_prototypes:
278 case OPT_Wwrite_strings:
282 /* This is handled by the front-end. */
287 gnat_argv[gnat_argc] = xstrdup ("-nostdlib");
292 gnat_argv[gnat_argc] = xstrdup ("-fRTS");
297 warning ("`-gnat' misspelled as `-gant'");
299 /* ... fall through ... */
302 /* Recopy the switches without the 'gnat' prefix. */
303 gnat_argv[gnat_argc] = xmalloc (strlen (arg) + 2);
304 gnat_argv[gnat_argc][0] = '-';
305 strcpy (gnat_argv[gnat_argc] + 1, arg);
309 for (i = 1; i < save_argc - 1; i++)
310 if (!strncmp (save_argv[i], "-gnatO", 6))
311 if (save_argv[++i][0] != '-')
313 /* Preserve output filename as GCC doesn't save it for GNAT. */
314 gnat_argv[gnat_argc] = xstrdup (save_argv[i]);
324 /* Initialize for option processing. */
327 gnat_init_options (unsigned int argc, const char **argv)
329 /* Initialize gnat_argv with save_argv size. */
330 gnat_argv = (char **) xmalloc ((argc + 1) * sizeof (argv[0]));
331 gnat_argv[0] = xstrdup (argv[0]); /* name of the command */
337 /* Uninitialized really means uninitialized in Ada. */
338 flag_zero_initialized_in_bss = 0;
343 /* Post-switch processing. */
346 gnat_post_options (const char **pfilename ATTRIBUTE_UNUSED)
348 flag_inline_trees = 1;
352 if (flag_inline_functions)
354 flag_inline_trees = 2;
355 flag_inline_functions = 0;
361 /* Here is the function to handle the compiler error processing in GCC. */
364 internal_error_function (const char *msgid, va_list *ap)
366 char buffer[1000]; /* Assume this is big enough. */
368 String_Template temp;
371 vsprintf (buffer, msgid, *ap);
373 /* Go up to the first newline. */
374 for (p = buffer; *p != 0; p++)
381 temp.Low_Bound = 1, temp.High_Bound = strlen (buffer);
382 fp.Array = buffer, fp.Bounds = &temp;
384 Current_Error_Node = error_gnat_node;
385 Compiler_Abort (fp, -1);
388 /* Perform all the initialization steps that are language-specific. */
393 /* Initialize translations and the outer statement group. */
394 gnat_init_stmt_group ();
396 /* Performs whatever initialization steps needed by the language-dependent
398 gnat_init_decl_processing ();
400 /* Add the input filename as the last argument. */
401 gnat_argv[gnat_argc] = (char *) main_input_filename;
403 gnat_argv[gnat_argc] = 0;
405 global_dc->internal_error = &internal_error_function;
407 /* Show that REFERENCE_TYPEs are internal and should be Pmode. */
408 internal_reference_types ();
410 set_lang_adjust_rli (gnat_adjust_rli);
415 /* This function is called indirectly from toplev.c to handle incomplete
416 declarations, i.e. VAR_DECL nodes whose DECL_SIZE is zero. To be precise,
417 compile_file in toplev.c makes an indirect call through the function pointer
418 incomplete_decl_finalize_hook which is initialized to this routine in
419 init_decl_processing. */
422 gnat_finish_incomplete_decl (tree dont_care ATTRIBUTE_UNUSED)
427 /* Compute the alignment of the largest mode that can be used for copying
431 gnat_compute_largest_alignment (void)
433 enum machine_mode mode;
435 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
436 mode = GET_MODE_WIDER_MODE (mode))
437 if (mov_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing)
438 largest_move_alignment = MIN (BIGGEST_ALIGNMENT,
439 MAX (largest_move_alignment,
440 GET_MODE_ALIGNMENT (mode)));
443 /* If we are using the GCC mechanism to process exception handling, we
444 have to register the personality routine for Ada and to initialize
445 various language dependent hooks. */
448 gnat_init_gcc_eh (void)
450 /* We shouldn't do anything if the No_Exceptions_Handler pragma is set,
451 though. This could for instance lead to the emission of tables with
452 references to symbols (such as the Ada eh personality routine) within
453 libraries we won't link against. */
454 if (No_Exception_Handlers_Set ())
457 /* Tell GCC we are handling cleanup actions through exception propagation.
458 This opens possibilities that we don't take advantage of yet, but is
459 nonetheless necessary to ensure that fixup code gets assigned to the
460 right exception regions. */
461 using_eh_for_cleanups ();
463 eh_personality_libfunc = init_one_libfunc ("__gnat_eh_personality");
464 lang_eh_type_covers = gnat_eh_type_covers;
465 lang_eh_runtime_type = gnat_eh_runtime_type;
467 /* Turn on -fexceptions and -fnon-call-exceptions. The first one triggers
468 the generation of the necessary exception runtime tables. The second one
469 is useful for two reasons: 1/ we map some asynchronous signals like SEGV
470 to exceptions, so we need to ensure that the insns which can lead to such
471 signals are correctly attached to the exception region they pertain to,
472 2/ Some calls to pure subprograms are handled as libcall blocks and then
473 marked as "cannot trap" if the flag is not set (see emit_libcall_block).
474 We should not let this be since it is possible for such calls to actually
478 flag_non_call_exceptions = 1;
481 #ifdef DWARF2_UNWIND_INFO
482 if (dwarf2out_do_frame ())
483 dwarf2out_frame_init ();
487 /* Language hooks, first one to print language-specific items in a DECL. */
490 gnat_print_decl (FILE *file, tree node, int indent)
492 switch (TREE_CODE (node))
495 print_node (file, "const_corresponding_var",
496 DECL_CONST_CORRESPONDING_VAR (node), indent + 4);
500 print_node (file, "original field", DECL_ORIGINAL_FIELD (node),
510 gnat_print_type (FILE *file, tree node, int indent)
512 switch (TREE_CODE (node))
515 print_node (file, "ci_co_list", TYPE_CI_CO_LIST (node), indent + 4);
519 print_node (file, "RM size", TYPE_RM_SIZE_ENUM (node), indent + 4);
523 if (TYPE_MODULAR_P (node))
524 print_node (file, "modulus", TYPE_MODULUS (node), indent + 4);
525 else if (TYPE_HAS_ACTUAL_BOUNDS_P (node))
526 print_node (file, "actual bounds", TYPE_ACTUAL_BOUNDS (node),
528 else if (TYPE_VAX_FLOATING_POINT_P (node))
531 print_node (file, "index type", TYPE_INDEX_TYPE (node), indent + 4);
533 print_node (file, "RM size", TYPE_RM_SIZE_INT (node), indent + 4);
537 print_node (file,"actual bounds", TYPE_ACTUAL_BOUNDS (node), indent + 4);
541 if (TYPE_IS_FAT_POINTER_P (node) || TYPE_CONTAINS_TEMPLATE_P (node))
542 print_node (file, "unconstrained array",
543 TYPE_UNCONSTRAINED_ARRAY (node), indent + 4);
545 print_node (file, "Ada size", TYPE_ADA_SIZE (node), indent + 4);
549 case QUAL_UNION_TYPE:
550 print_node (file, "Ada size", TYPE_ADA_SIZE (node), indent + 4);
559 gnat_printable_name (tree decl, int verbosity)
561 const char *coded_name = IDENTIFIER_POINTER (DECL_NAME (decl));
562 char *ada_name = (char *) ggc_alloc (strlen (coded_name) * 2 + 60);
564 __gnat_decode (coded_name, ada_name, 0);
568 Set_Identifier_Casing (ada_name, (char *) DECL_SOURCE_FILE (decl));
569 ada_name = Name_Buffer;
572 return (const char *) ada_name;
575 /* Expands GNAT-specific GCC tree nodes. The only ones we support
576 here are and NULL_EXPR. */
579 gnat_expand_expr (tree exp, rtx target, enum machine_mode tmode,
580 int modifier, rtx *alt_rtl)
582 tree type = TREE_TYPE (exp);
585 /* If this is a statement, call the expansion routine for statements. */
588 gnat_expand_stmt (exp);
592 /* Update EXP to be the new expression to expand. */
593 switch (TREE_CODE (exp))
598 allocate_dynamic_stack_space
599 (expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, TYPE_MODE (sizetype),
601 NULL_RTX, tree_low_cst (TREE_OPERAND (exp, 1), 1));
604 case UNCONSTRAINED_ARRAY_REF:
605 /* If we are evaluating just for side-effects, just evaluate our
606 operand. Otherwise, abort since this code should never appear
607 in a tree to be evaluated (objects aren't unconstrained). */
608 if (target == const0_rtx || TREE_CODE (type) == VOID_TYPE)
609 return expand_expr (TREE_OPERAND (exp, 0), const0_rtx,
612 /* ... fall through ... */
618 return expand_expr_real (new, target, tmode, modifier, alt_rtl);
621 /* Adjusts the RLI used to layout a record after all the fields have been
622 added. We only handle the packed case and cause it to use the alignment
623 that will pad the record at the end. */
626 gnat_adjust_rli (record_layout_info rli ATTRIBUTE_UNUSED)
629 /* ??? This code seems to have no actual effect; record_align should already
630 reflect the largest alignment desired by a field. jason 2003-04-01 */
631 unsigned int record_align = rli->unpadded_align;
634 /* If an alignment has been specified, don't use anything larger unless we
636 if (TYPE_ALIGN (rli->t) != 0 && TYPE_ALIGN (rli->t) < record_align)
637 record_align = MAX (rli->record_align, TYPE_ALIGN (rli->t));
639 /* If any fields have variable size, we need to force the record to be at
640 least as aligned as the alignment of that type. */
641 for (field = TYPE_FIELDS (rli->t); field; field = TREE_CHAIN (field))
642 if (TREE_CODE (DECL_SIZE_UNIT (field)) != INTEGER_CST)
643 record_align = MAX (record_align, DECL_ALIGN (field));
645 if (TYPE_PACKED (rli->t))
646 rli->record_align = record_align;
650 /* These routines are used in conjunction with GCC exception handling. */
652 /* Map compile-time to run-time tree for GCC exception handling scheme. */
655 gnat_eh_runtime_type (tree type)
660 /* Return true if type A catches type B. Callback for flow analysis from
661 the exception handling part of the back-end. */
664 gnat_eh_type_covers (tree a, tree b)
666 /* a catches b if they represent the same exception id or if a
669 ??? integer_zero_node for "others" is hardwired in too many places
671 return (a == b || a == integer_zero_node);
674 /* Get the alias set corresponding to a type or expression. */
677 gnat_get_alias_set (tree type)
679 /* If this is a padding type, use the type of the first field. */
680 if (TREE_CODE (type) == RECORD_TYPE
681 && TYPE_IS_PADDING_P (type))
682 return get_alias_set (TREE_TYPE (TYPE_FIELDS (type)));
684 /* If the type is an unconstrained array, use the type of the
685 self-referential array we make. */
686 else if (TREE_CODE (type) == UNCONSTRAINED_ARRAY_TYPE)
688 get_alias_set (TREE_TYPE (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (type)))));
694 /* GNU_TYPE is a type. Determine if it should be passed by reference by
698 default_pass_by_ref (tree gnu_type)
700 /* We pass aggregates by reference if they are sufficiently large. The
701 choice of constant here is somewhat arbitrary. We also pass by
702 reference if the target machine would either pass or return by
703 reference. Strictly speaking, we need only check the return if this
704 is an In Out parameter, but it's probably best to err on the side of
705 passing more things by reference. */
707 if (pass_by_reference (NULL, TYPE_MODE (gnu_type), gnu_type, 1))
710 if (targetm.calls.return_in_memory (gnu_type, NULL_TREE))
713 if (AGGREGATE_TYPE_P (gnu_type)
714 && (! host_integerp (TYPE_SIZE (gnu_type), 1)
715 || 0 < compare_tree_int (TYPE_SIZE (gnu_type),
716 8 * TYPE_ALIGN (gnu_type))))
722 /* GNU_TYPE is the type of a subprogram parameter. Determine from the type if
723 it should be passed by reference. */
726 must_pass_by_ref (tree gnu_type)
728 /* We pass only unconstrained objects, those required by the language
729 to be passed by reference, and objects of variable size. The latter
730 is more efficient, avoids problems with variable size temporaries,
731 and does not produce compatibility problems with C, since C does
732 not have such objects. */
733 return (TREE_CODE (gnu_type) == UNCONSTRAINED_ARRAY_TYPE
734 || (AGGREGATE_TYPE_P (gnu_type) && TYPE_BY_REFERENCE_P (gnu_type))
735 || (TYPE_SIZE (gnu_type) != 0
736 && TREE_CODE (TYPE_SIZE (gnu_type)) != INTEGER_CST));
739 /* This function is called by the front end to enumerate all the supported
740 modes for the machine. We pass a function which is called back with
741 the following integer parameters:
743 FLOAT_P nonzero if this represents a floating-point mode
744 COMPLEX_P nonzero is this represents a complex mode
745 COUNT count of number of items, nonzero for vector mode
746 PRECISION number of bits in data representation
747 MANTISSA number of bits in mantissa, if FP and known, else zero.
748 SIZE number of bits used to store data
749 ALIGN number of bits to which mode is aligned. */
752 enumerate_modes (void (*f) (int, int, int, int, int, int, unsigned int))
756 for (i = 0; i < NUM_MACHINE_MODES; i++)
764 enum machine_mode inner_mode = i;
766 switch (GET_MODE_CLASS (i))
773 case MODE_COMPLEX_INT:
775 inner_mode = GET_MODE_INNER (i);
777 case MODE_COMPLEX_FLOAT:
780 inner_mode = GET_MODE_INNER (i);
782 case MODE_VECTOR_INT:
784 inner_mode = GET_MODE_INNER (i);
786 case MODE_VECTOR_FLOAT:
789 inner_mode = GET_MODE_INNER (i);
795 /* Skip this mode if it's one the front end doesn't need to know about
796 (e.g., the CC modes) or if there is no add insn for that mode (or
797 any wider mode), meaning it is not supported by the hardware. If
798 this a complex or vector mode, we care about the inner mode. */
799 for (j = inner_mode; j != VOIDmode; j = GET_MODE_WIDER_MODE (j))
800 if (add_optab->handlers[j].insn_code != CODE_FOR_nothing)
805 const struct real_format *fmt = REAL_MODE_FORMAT (inner_mode);
807 mantissa = fmt->p * fmt->log2_b;
810 if (!skip_p && j != VOIDmode)
811 (*f) (float_p, complex_p, vector_p ? GET_MODE_NUNITS (i) : 0,
812 GET_MODE_BITSIZE (i), mantissa,
813 GET_MODE_SIZE (i) * BITS_PER_UNIT, GET_MODE_ALIGNMENT (i));
818 fp_prec_to_size (int prec)
820 enum machine_mode mode;
822 for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT); mode != VOIDmode;
823 mode = GET_MODE_WIDER_MODE (mode))
824 if (GET_MODE_PRECISION (mode) == prec)
825 return GET_MODE_BITSIZE (mode);
831 fp_size_to_prec (int size)
833 enum machine_mode mode;
835 for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT); mode != VOIDmode;
836 mode = GET_MODE_WIDER_MODE (mode))
837 if (GET_MODE_BITSIZE (mode) == size)
838 return GET_MODE_PRECISION (mode);