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9bf86ebb PR |
1 | /* Utility routines for data type conversion for GNU C. |
2 | Copyright (C) 1987, 1988, 1991, 1992 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GNU C. | |
5 | ||
6 | GNU CC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GNU CC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU CC; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | ||
21 | /* These routines are somewhat language-independent utility function | |
22 | intended to be called by the language-specific convert () functions. */ | |
23 | ||
24 | #include "config.h" | |
25 | #include "tree.h" | |
26 | #include "flags.h" | |
27 | #include "convert.h" | |
28 | ||
29 | /* Convert EXPR to some pointer type TYPE. | |
30 | ||
31 | EXPR must be pointer, integer, enumeral, or literal zero; | |
32 | in other cases error is called. */ | |
33 | ||
34 | tree | |
35 | convert_to_pointer (type, expr) | |
36 | tree type, expr; | |
37 | { | |
38 | register tree intype = TREE_TYPE (expr); | |
39 | register enum tree_code form = TREE_CODE (intype); | |
40 | ||
41 | if (integer_zerop (expr)) | |
42 | { | |
43 | if (type == TREE_TYPE (null_pointer_node)) | |
44 | return null_pointer_node; | |
45 | expr = build_int_2 (0, 0); | |
46 | TREE_TYPE (expr) = type; | |
47 | return expr; | |
48 | } | |
49 | ||
50 | if (form == POINTER_TYPE) | |
51 | return build1 (NOP_EXPR, type, expr); | |
52 | ||
53 | ||
54 | if (form == INTEGER_TYPE || form == ENUMERAL_TYPE) | |
55 | { | |
56 | if (type_precision (intype) == POINTER_SIZE) | |
57 | return build1 (CONVERT_EXPR, type, expr); | |
58 | expr = convert (type_for_size (POINTER_SIZE, 0), expr); | |
59 | /* Modes may be different but sizes should be the same. */ | |
60 | if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))) | |
61 | != GET_MODE_SIZE (TYPE_MODE (type))) | |
62 | /* There is supposed to be some integral type | |
63 | that is the same width as a pointer. */ | |
64 | abort (); | |
65 | return convert_to_pointer (type, expr); | |
66 | } | |
67 | ||
68 | error ("cannot convert to a pointer type"); | |
69 | ||
70 | return null_pointer_node; | |
71 | } | |
72 | ||
73 | /* Convert EXPR to some floating-point type TYPE. | |
74 | ||
75 | EXPR must be float, integer, or enumeral; | |
76 | in other cases error is called. */ | |
77 | ||
78 | tree | |
79 | convert_to_real (type, expr) | |
80 | tree type, expr; | |
81 | { | |
82 | register enum tree_code form = TREE_CODE (TREE_TYPE (expr)); | |
83 | ||
84 | if (form == REAL_TYPE) | |
85 | return build1 (flag_float_store ? CONVERT_EXPR : NOP_EXPR, | |
86 | type, expr); | |
87 | ||
88 | if (form == INTEGER_TYPE || form == ENUMERAL_TYPE) | |
89 | return build1 (FLOAT_EXPR, type, expr); | |
90 | ||
91 | if (form == COMPLEX_TYPE) | |
92 | return convert (type, fold (build1 (REALPART_EXPR, | |
93 | TREE_TYPE (TREE_TYPE (expr)), expr))); | |
94 | ||
95 | if (form == POINTER_TYPE) | |
96 | error ("pointer value used where a floating point value was expected"); | |
97 | else | |
98 | error ("aggregate value used where a float was expected"); | |
99 | ||
100 | { | |
101 | register tree tem = make_node (REAL_CST); | |
102 | TREE_TYPE (tem) = type; | |
103 | TREE_REAL_CST (tem) = REAL_VALUE_ATOF ("0.0", TYPE_MODE (type)); | |
104 | return tem; | |
105 | } | |
106 | } | |
107 | ||
108 | /* Convert EXPR to some integer (or enum) type TYPE. | |
109 | ||
110 | EXPR must be pointer, integer, discrete (enum, char, or bool), or float; | |
111 | in other cases error is called. | |
112 | ||
113 | The result of this is always supposed to be a newly created tree node | |
114 | not in use in any existing structure. */ | |
115 | ||
116 | tree | |
117 | convert_to_integer (type, expr) | |
118 | tree type, expr; | |
119 | { | |
120 | register tree intype = TREE_TYPE (expr); | |
121 | register enum tree_code form = TREE_CODE (intype); | |
122 | ||
123 | if (form == POINTER_TYPE) | |
124 | { | |
125 | if (integer_zerop (expr)) | |
126 | expr = integer_zero_node; | |
127 | else | |
128 | expr = fold (build1 (CONVERT_EXPR, | |
129 | type_for_size (POINTER_SIZE, 0), expr)); | |
130 | intype = TREE_TYPE (expr); | |
131 | form = TREE_CODE (intype); | |
132 | if (intype == type) | |
133 | return expr; | |
134 | } | |
135 | ||
136 | if (form == INTEGER_TYPE || form == ENUMERAL_TYPE | |
137 | || form == BOOLEAN_TYPE || form == CHAR_TYPE) | |
138 | { | |
139 | register unsigned outprec = TYPE_PRECISION (type); | |
140 | register unsigned inprec = TYPE_PRECISION (intype); | |
141 | register enum tree_code ex_form = TREE_CODE (expr); | |
142 | ||
143 | /* If we are widening the type, put in an explicit conversion. | |
144 | Similarly if we are not changing the width. However, if this is | |
145 | a logical operation that just returns 0 or 1, we can change the | |
146 | type of the expression (see below). */ | |
147 | ||
148 | if (TREE_CODE_CLASS (ex_form) == '<' | |
149 | || ex_form == TRUTH_AND_EXPR || ex_form == TRUTH_ANDIF_EXPR | |
150 | || ex_form == TRUTH_OR_EXPR || ex_form == TRUTH_ORIF_EXPR | |
151 | || ex_form == TRUTH_XOR_EXPR || ex_form == TRUTH_NOT_EXPR) | |
152 | { | |
153 | TREE_TYPE (expr) = type; | |
154 | return expr; | |
155 | } | |
156 | else if (outprec >= inprec) | |
157 | return build1 (NOP_EXPR, type, expr); | |
158 | ||
159 | /* Here detect when we can distribute the truncation down past some arithmetic. | |
160 | For example, if adding two longs and converting to an int, | |
161 | we can equally well convert both to ints and then add. | |
162 | For the operations handled here, such truncation distribution | |
163 | is always safe. | |
164 | It is desirable in these cases: | |
165 | 1) when truncating down to full-word from a larger size | |
166 | 2) when truncating takes no work. | |
167 | 3) when at least one operand of the arithmetic has been extended | |
168 | (as by C's default conversions). In this case we need two conversions | |
169 | if we do the arithmetic as already requested, so we might as well | |
170 | truncate both and then combine. Perhaps that way we need only one. | |
171 | ||
172 | Note that in general we cannot do the arithmetic in a type | |
173 | shorter than the desired result of conversion, even if the operands | |
174 | are both extended from a shorter type, because they might overflow | |
175 | if combined in that type. The exceptions to this--the times when | |
176 | two narrow values can be combined in their narrow type even to | |
177 | make a wider result--are handled by "shorten" in build_binary_op. */ | |
178 | ||
179 | switch (ex_form) | |
180 | { | |
181 | case RSHIFT_EXPR: | |
182 | /* We can pass truncation down through right shifting | |
183 | when the shift count is a nonpositive constant. */ | |
184 | if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST | |
185 | && tree_int_cst_lt (TREE_OPERAND (expr, 1), integer_one_node)) | |
186 | goto trunc1; | |
187 | break; | |
188 | ||
189 | case LSHIFT_EXPR: | |
190 | /* We can pass truncation down through left shifting | |
191 | when the shift count is a nonnegative constant. */ | |
192 | if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST | |
193 | && ! tree_int_cst_lt (TREE_OPERAND (expr, 1), integer_zero_node) | |
194 | && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST) | |
195 | { | |
196 | /* If shift count is less than the width of the truncated type, | |
197 | really shift. */ | |
198 | if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type))) | |
199 | /* In this case, shifting is like multiplication. */ | |
200 | goto trunc1; | |
201 | else | |
202 | { | |
203 | /* If it is >= that width, result is zero. | |
204 | Handling this with trunc1 would give the wrong result: | |
205 | (int) ((long long) a << 32) is well defined (as 0) | |
206 | but (int) a << 32 is undefined and would get a | |
207 | warning. */ | |
208 | ||
209 | tree t = convert_to_integer (type, integer_zero_node); | |
210 | ||
211 | /* If the original expression had side-effects, we must | |
212 | preserve it. */ | |
213 | if (TREE_SIDE_EFFECTS (expr)) | |
214 | return build (COMPOUND_EXPR, type, expr, t); | |
215 | else | |
216 | return t; | |
217 | } | |
218 | } | |
219 | break; | |
220 | ||
221 | case MAX_EXPR: | |
222 | case MIN_EXPR: | |
223 | case MULT_EXPR: | |
224 | { | |
225 | tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type); | |
226 | tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type); | |
227 | ||
228 | /* Don't distribute unless the output precision is at least as big | |
229 | as the actual inputs. Otherwise, the comparison of the | |
230 | truncated values will be wrong. */ | |
231 | if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0)) | |
232 | && outprec >= TYPE_PRECISION (TREE_TYPE (arg1)) | |
233 | /* If signedness of arg0 and arg1 don't match, | |
234 | we can't necessarily find a type to compare them in. */ | |
235 | && (TREE_UNSIGNED (TREE_TYPE (arg0)) | |
236 | == TREE_UNSIGNED (TREE_TYPE (arg1)))) | |
237 | goto trunc1; | |
238 | break; | |
239 | } | |
240 | ||
241 | case PLUS_EXPR: | |
242 | case MINUS_EXPR: | |
243 | case BIT_AND_EXPR: | |
244 | case BIT_IOR_EXPR: | |
245 | case BIT_XOR_EXPR: | |
246 | case BIT_ANDTC_EXPR: | |
247 | trunc1: | |
248 | { | |
249 | tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type); | |
250 | tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type); | |
251 | ||
252 | if (outprec >= BITS_PER_WORD | |
253 | || TRULY_NOOP_TRUNCATION (outprec, inprec) | |
254 | || inprec > TYPE_PRECISION (TREE_TYPE (arg0)) | |
255 | || inprec > TYPE_PRECISION (TREE_TYPE (arg1))) | |
256 | { | |
257 | /* Do the arithmetic in type TYPEX, | |
258 | then convert result to TYPE. */ | |
259 | register tree typex = type; | |
260 | ||
261 | /* Can't do arithmetic in enumeral types | |
262 | so use an integer type that will hold the values. */ | |
263 | if (TREE_CODE (typex) == ENUMERAL_TYPE) | |
264 | typex = type_for_size (TYPE_PRECISION (typex), | |
265 | TREE_UNSIGNED (typex)); | |
266 | ||
267 | /* But now perhaps TYPEX is as wide as INPREC. | |
268 | In that case, do nothing special here. | |
269 | (Otherwise would recurse infinitely in convert. */ | |
270 | if (TYPE_PRECISION (typex) != inprec) | |
271 | { | |
272 | /* Don't do unsigned arithmetic where signed was wanted, | |
273 | or vice versa. | |
274 | Exception: if either of the original operands were | |
275 | unsigned then can safely do the work as unsigned. | |
276 | And we may need to do it as unsigned | |
277 | if we truncate to the original size. */ | |
278 | typex = ((TREE_UNSIGNED (TREE_TYPE (expr)) | |
279 | || TREE_UNSIGNED (TREE_TYPE (arg0)) | |
280 | || TREE_UNSIGNED (TREE_TYPE (arg1))) | |
281 | ? unsigned_type (typex) : signed_type (typex)); | |
282 | return convert (type, | |
283 | fold (build (ex_form, typex, | |
284 | convert (typex, arg0), | |
285 | convert (typex, arg1), | |
286 | 0))); | |
287 | } | |
288 | } | |
289 | } | |
290 | break; | |
291 | ||
292 | case NEGATE_EXPR: | |
293 | case BIT_NOT_EXPR: | |
294 | case ABS_EXPR: | |
295 | { | |
296 | register tree typex = type; | |
297 | ||
298 | /* Can't do arithmetic in enumeral types | |
299 | so use an integer type that will hold the values. */ | |
300 | if (TREE_CODE (typex) == ENUMERAL_TYPE) | |
301 | typex = type_for_size (TYPE_PRECISION (typex), | |
302 | TREE_UNSIGNED (typex)); | |
303 | ||
304 | /* But now perhaps TYPEX is as wide as INPREC. | |
305 | In that case, do nothing special here. | |
306 | (Otherwise would recurse infinitely in convert. */ | |
307 | if (TYPE_PRECISION (typex) != inprec) | |
308 | { | |
309 | /* Don't do unsigned arithmetic where signed was wanted, | |
310 | or vice versa. */ | |
311 | typex = (TREE_UNSIGNED (TREE_TYPE (expr)) | |
312 | ? unsigned_type (typex) : signed_type (typex)); | |
313 | return convert (type, | |
314 | fold (build1 (ex_form, typex, | |
315 | convert (typex, | |
316 | TREE_OPERAND (expr, 0))))); | |
317 | } | |
318 | } | |
319 | ||
320 | case NOP_EXPR: | |
321 | /* If truncating after truncating, might as well do all at once. | |
322 | If truncating after extending, we may get rid of wasted work. */ | |
323 | return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type)); | |
324 | ||
325 | case COND_EXPR: | |
326 | /* Can treat the two alternative values like the operands | |
327 | of an arithmetic expression. */ | |
328 | { | |
329 | tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type); | |
330 | tree arg2 = get_unwidened (TREE_OPERAND (expr, 2), type); | |
331 | ||
332 | if (outprec >= BITS_PER_WORD | |
333 | || TRULY_NOOP_TRUNCATION (outprec, inprec) | |
334 | || inprec > TYPE_PRECISION (TREE_TYPE (arg1)) | |
335 | || inprec > TYPE_PRECISION (TREE_TYPE (arg2))) | |
336 | { | |
337 | /* Do the arithmetic in type TYPEX, | |
338 | then convert result to TYPE. */ | |
339 | register tree typex = type; | |
340 | ||
341 | /* Can't do arithmetic in enumeral types | |
342 | so use an integer type that will hold the values. */ | |
343 | if (TREE_CODE (typex) == ENUMERAL_TYPE) | |
344 | typex = type_for_size (TYPE_PRECISION (typex), | |
345 | TREE_UNSIGNED (typex)); | |
346 | ||
347 | /* But now perhaps TYPEX is as wide as INPREC. | |
348 | In that case, do nothing special here. | |
349 | (Otherwise would recurse infinitely in convert. */ | |
350 | if (TYPE_PRECISION (typex) != inprec) | |
351 | { | |
352 | /* Don't do unsigned arithmetic where signed was wanted, | |
353 | or vice versa. */ | |
354 | typex = (TREE_UNSIGNED (TREE_TYPE (expr)) | |
355 | ? unsigned_type (typex) : signed_type (typex)); | |
356 | return convert (type, | |
357 | fold (build (COND_EXPR, typex, | |
358 | TREE_OPERAND (expr, 0), | |
359 | convert (typex, arg1), | |
360 | convert (typex, arg2)))); | |
361 | } | |
362 | else | |
363 | /* It is sometimes worthwhile | |
364 | to push the narrowing down through the conditional. */ | |
365 | return fold (build (COND_EXPR, type, | |
366 | TREE_OPERAND (expr, 0), | |
367 | convert (type, TREE_OPERAND (expr, 1)), | |
368 | convert (type, TREE_OPERAND (expr, 2)))); | |
369 | } | |
370 | } | |
371 | ||
372 | } | |
373 | ||
374 | return build1 (NOP_EXPR, type, expr); | |
375 | } | |
376 | ||
377 | if (form == REAL_TYPE) | |
378 | return build1 (FIX_TRUNC_EXPR, type, expr); | |
379 | ||
380 | if (form == COMPLEX_TYPE) | |
381 | return convert (type, fold (build1 (REALPART_EXPR, | |
382 | TREE_TYPE (TREE_TYPE (expr)), expr))); | |
383 | ||
384 | error ("aggregate value used where an integer was expected"); | |
385 | ||
386 | { | |
387 | register tree tem = build_int_2 (0, 0); | |
388 | TREE_TYPE (tem) = type; | |
389 | return tem; | |
390 | } | |
391 | } | |
392 | ||
393 | /* Convert EXPR to the complex type TYPE in the usual ways. */ | |
394 | ||
395 | tree | |
396 | convert_to_complex (type, expr) | |
397 | tree type, expr; | |
398 | { | |
399 | register enum tree_code form = TREE_CODE (TREE_TYPE (expr)); | |
400 | tree subtype = TREE_TYPE (type); | |
401 | ||
402 | if (form == REAL_TYPE || form == INTEGER_TYPE || form == ENUMERAL_TYPE) | |
403 | { | |
404 | expr = convert (subtype, expr); | |
405 | return build (COMPLEX_EXPR, type, expr, | |
406 | convert (subtype, integer_zero_node)); | |
407 | } | |
408 | ||
409 | if (form == COMPLEX_TYPE) | |
410 | { | |
411 | tree elt_type = TREE_TYPE (TREE_TYPE (expr)); | |
412 | if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype)) | |
413 | return expr; | |
414 | else if (TREE_CODE (expr) == COMPLEX_EXPR) | |
415 | return fold (build (COMPLEX_EXPR, | |
416 | type, | |
417 | convert (subtype, TREE_OPERAND (expr, 0)), | |
418 | convert (subtype, TREE_OPERAND (expr, 1)))); | |
419 | else | |
420 | { | |
421 | expr = save_expr (expr); | |
422 | return fold (build (COMPLEX_EXPR, | |
423 | type, | |
424 | convert (subtype, | |
425 | fold (build1 (REALPART_EXPR, | |
426 | TREE_TYPE (TREE_TYPE (expr)), | |
427 | expr))), | |
428 | convert (subtype, | |
429 | fold (build1 (IMAGPART_EXPR, | |
430 | TREE_TYPE (TREE_TYPE (expr)), | |
431 | expr))))); | |
432 | } | |
433 | } | |
434 | ||
435 | if (form == POINTER_TYPE) | |
436 | error ("pointer value used where a complex was expected"); | |
437 | else | |
438 | error ("aggregate value used where a complex was expected"); | |
439 | ||
440 | return build (COMPLEX_EXPR, type, | |
441 | convert (subtype, integer_zero_node), | |
442 | convert (subtype, integer_zero_node)); | |
443 | } |