1 /* Utility routines for data type conversion for GNU C.
2 Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1997,
3 1998 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 /* These routines are somewhat language-independent utility function
24 intended to be called by the language-specific convert () functions. */
32 #include "langhooks.h"
34 /* Convert EXPR to some pointer or reference type TYPE.
36 EXPR must be pointer, reference, integer, enumeral, or literal zero;
37 in other cases error is called. */
40 convert_to_pointer (type, expr)
43 if (integer_zerop (expr))
45 expr = build_int_2 (0, 0);
46 TREE_TYPE (expr) = type;
50 switch (TREE_CODE (TREE_TYPE (expr)))
54 return build1 (NOP_EXPR, type, expr);
60 if (TYPE_PRECISION (TREE_TYPE (expr)) == POINTER_SIZE)
61 return build1 (CONVERT_EXPR, type, expr);
64 convert_to_pointer (type,
65 convert ((*lang_hooks.types.type_for_size)
66 (POINTER_SIZE, 0), expr));
69 error ("cannot convert to a pointer type");
70 return convert_to_pointer (type, integer_zero_node);
74 /* Convert EXPR to some floating-point type TYPE.
76 EXPR must be float, integer, or enumeral;
77 in other cases error is called. */
80 convert_to_real (type, expr)
83 switch (TREE_CODE (TREE_TYPE (expr)))
86 return build1 (flag_float_store ? CONVERT_EXPR : NOP_EXPR,
93 return build1 (FLOAT_EXPR, type, expr);
97 fold (build1 (REALPART_EXPR,
98 TREE_TYPE (TREE_TYPE (expr)), expr)));
102 error ("pointer value used where a floating point value was expected");
103 return convert_to_real (type, integer_zero_node);
106 error ("aggregate value used where a float was expected");
107 return convert_to_real (type, integer_zero_node);
111 /* Convert EXPR to some integer (or enum) type TYPE.
113 EXPR must be pointer, integer, discrete (enum, char, or bool), float, or
114 vector; in other cases error is called.
116 The result of this is always supposed to be a newly created tree node
117 not in use in any existing structure. */
120 convert_to_integer (type, expr)
123 enum tree_code ex_form = TREE_CODE (expr);
124 tree intype = TREE_TYPE (expr);
125 unsigned int inprec = TYPE_PRECISION (intype);
126 unsigned int outprec = TYPE_PRECISION (type);
128 /* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
129 be. Consider `enum E = { a, b = (enum E) 3 };'. */
130 if (!COMPLETE_TYPE_P (type))
132 error ("conversion to incomplete type");
133 return error_mark_node;
136 switch (TREE_CODE (intype))
140 if (integer_zerop (expr))
141 expr = integer_zero_node;
143 expr = fold (build1 (CONVERT_EXPR, (*lang_hooks.types.type_for_size)
144 (POINTER_SIZE, 0), expr));
146 return convert_to_integer (type, expr);
152 /* If this is a logical operation, which just returns 0 or 1, we can
153 change the type of the expression. For some logical operations,
154 we must also change the types of the operands to maintain type
157 if (TREE_CODE_CLASS (ex_form) == '<')
159 TREE_TYPE (expr) = type;
163 else if (ex_form == TRUTH_AND_EXPR || ex_form == TRUTH_ANDIF_EXPR
164 || ex_form == TRUTH_OR_EXPR || ex_form == TRUTH_ORIF_EXPR
165 || ex_form == TRUTH_XOR_EXPR)
167 TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0));
168 TREE_OPERAND (expr, 1) = convert (type, TREE_OPERAND (expr, 1));
169 TREE_TYPE (expr) = type;
173 else if (ex_form == TRUTH_NOT_EXPR)
175 TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0));
176 TREE_TYPE (expr) = type;
180 /* If we are widening the type, put in an explicit conversion.
181 Similarly if we are not changing the width. After this, we know
182 we are truncating EXPR. */
184 else if (outprec >= inprec)
185 return build1 (NOP_EXPR, type, expr);
187 /* If TYPE is an enumeral type or a type with a precision less
188 than the number of bits in its mode, do the conversion to the
189 type corresponding to its mode, then do a nop conversion
191 else if (TREE_CODE (type) == ENUMERAL_TYPE
192 || outprec != GET_MODE_BITSIZE (TYPE_MODE (type)))
193 return build1 (NOP_EXPR, type,
194 convert ((*lang_hooks.types.type_for_mode)
195 (TYPE_MODE (type), TREE_UNSIGNED (type)),
198 /* Here detect when we can distribute the truncation down past some
199 arithmetic. For example, if adding two longs and converting to an
200 int, we can equally well convert both to ints and then add.
201 For the operations handled here, such truncation distribution
203 It is desirable in these cases:
204 1) when truncating down to full-word from a larger size
205 2) when truncating takes no work.
206 3) when at least one operand of the arithmetic has been extended
207 (as by C's default conversions). In this case we need two conversions
208 if we do the arithmetic as already requested, so we might as well
209 truncate both and then combine. Perhaps that way we need only one.
211 Note that in general we cannot do the arithmetic in a type
212 shorter than the desired result of conversion, even if the operands
213 are both extended from a shorter type, because they might overflow
214 if combined in that type. The exceptions to this--the times when
215 two narrow values can be combined in their narrow type even to
216 make a wider result--are handled by "shorten" in build_binary_op. */
221 /* We can pass truncation down through right shifting
222 when the shift count is a nonpositive constant. */
223 if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
224 && tree_int_cst_lt (TREE_OPERAND (expr, 1),
225 convert (TREE_TYPE (TREE_OPERAND (expr, 1)),
231 /* We can pass truncation down through left shifting
232 when the shift count is a nonnegative constant. */
233 if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
234 && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
235 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
237 /* If shift count is less than the width of the truncated type,
239 if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
240 /* In this case, shifting is like multiplication. */
244 /* If it is >= that width, result is zero.
245 Handling this with trunc1 would give the wrong result:
246 (int) ((long long) a << 32) is well defined (as 0)
247 but (int) a << 32 is undefined and would get a
250 tree t = convert_to_integer (type, integer_zero_node);
252 /* If the original expression had side-effects, we must
254 if (TREE_SIDE_EFFECTS (expr))
255 return build (COMPOUND_EXPR, type, expr, t);
266 tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
267 tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
269 /* Don't distribute unless the output precision is at least as big
270 as the actual inputs. Otherwise, the comparison of the
271 truncated values will be wrong. */
272 if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
273 && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
274 /* If signedness of arg0 and arg1 don't match,
275 we can't necessarily find a type to compare them in. */
276 && (TREE_UNSIGNED (TREE_TYPE (arg0))
277 == TREE_UNSIGNED (TREE_TYPE (arg1))))
290 tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
291 tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
293 if (outprec >= BITS_PER_WORD
294 || TRULY_NOOP_TRUNCATION (outprec, inprec)
295 || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
296 || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
298 /* Do the arithmetic in type TYPEX,
299 then convert result to TYPE. */
302 /* Can't do arithmetic in enumeral types
303 so use an integer type that will hold the values. */
304 if (TREE_CODE (typex) == ENUMERAL_TYPE)
305 typex = (*lang_hooks.types.type_for_size)
306 (TYPE_PRECISION (typex), TREE_UNSIGNED (typex));
308 /* But now perhaps TYPEX is as wide as INPREC.
309 In that case, do nothing special here.
310 (Otherwise would recurse infinitely in convert. */
311 if (TYPE_PRECISION (typex) != inprec)
313 /* Don't do unsigned arithmetic where signed was wanted,
315 Exception: if both of the original operands were
316 unsigned then can safely do the work as unsigned.
317 And we may need to do it as unsigned
318 if we truncate to the original size. */
319 typex = ((TREE_UNSIGNED (TREE_TYPE (expr))
320 || (TREE_UNSIGNED (TREE_TYPE (arg0))
321 && TREE_UNSIGNED (TREE_TYPE (arg1))))
322 ? unsigned_type (typex) : signed_type (typex));
323 return convert (type,
324 fold (build (ex_form, typex,
325 convert (typex, arg0),
326 convert (typex, arg1),
335 /* This is not correct for ABS_EXPR,
336 since we must test the sign before truncation. */
340 /* Can't do arithmetic in enumeral types
341 so use an integer type that will hold the values. */
342 if (TREE_CODE (typex) == ENUMERAL_TYPE)
343 typex = (*lang_hooks.types.type_for_size)
344 (TYPE_PRECISION (typex), TREE_UNSIGNED (typex));
346 /* But now perhaps TYPEX is as wide as INPREC.
347 In that case, do nothing special here.
348 (Otherwise would recurse infinitely in convert. */
349 if (TYPE_PRECISION (typex) != inprec)
351 /* Don't do unsigned arithmetic where signed was wanted,
353 typex = (TREE_UNSIGNED (TREE_TYPE (expr))
354 ? unsigned_type (typex) : signed_type (typex));
355 return convert (type,
356 fold (build1 (ex_form, typex,
358 TREE_OPERAND (expr, 0)))));
363 /* If truncating after truncating, might as well do all at once.
364 If truncating after extending, we may get rid of wasted work. */
365 return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
368 /* It is sometimes worthwhile to push the narrowing down through
369 the conditional and never loses. */
370 return fold (build (COND_EXPR, type, TREE_OPERAND (expr, 0),
371 convert (type, TREE_OPERAND (expr, 1)),
372 convert (type, TREE_OPERAND (expr, 2))));
378 return build1 (NOP_EXPR, type, expr);
381 return build1 (FIX_TRUNC_EXPR, type, expr);
384 return convert (type,
385 fold (build1 (REALPART_EXPR,
386 TREE_TYPE (TREE_TYPE (expr)), expr)));
389 if (GET_MODE_SIZE (TYPE_MODE (type))
390 != GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))))
392 error ("can't convert between vector values of different size");
393 return error_mark_node;
395 return build1 (NOP_EXPR, type, expr);
398 error ("aggregate value used where an integer was expected");
399 return convert (type, integer_zero_node);
403 /* Convert EXPR to the complex type TYPE in the usual ways. */
406 convert_to_complex (type, expr)
409 tree subtype = TREE_TYPE (type);
411 switch (TREE_CODE (TREE_TYPE (expr)))
418 return build (COMPLEX_EXPR, type, convert (subtype, expr),
419 convert (subtype, integer_zero_node));
423 tree elt_type = TREE_TYPE (TREE_TYPE (expr));
425 if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
427 else if (TREE_CODE (expr) == COMPLEX_EXPR)
428 return fold (build (COMPLEX_EXPR,
430 convert (subtype, TREE_OPERAND (expr, 0)),
431 convert (subtype, TREE_OPERAND (expr, 1))));
434 expr = save_expr (expr);
436 fold (build (COMPLEX_EXPR,
437 type, convert (subtype,
438 fold (build1 (REALPART_EXPR,
439 TREE_TYPE (TREE_TYPE (expr)),
442 fold (build1 (IMAGPART_EXPR,
443 TREE_TYPE (TREE_TYPE (expr)),
450 error ("pointer value used where a complex was expected");
451 return convert_to_complex (type, integer_zero_node);
454 error ("aggregate value used where a complex was expected");
455 return convert_to_complex (type, integer_zero_node);
459 /* Convert EXPR to the vector type TYPE in the usual ways. */
462 convert_to_vector (type, expr)
465 switch (TREE_CODE (TREE_TYPE (expr)))
469 if (GET_MODE_SIZE (TYPE_MODE (type))
470 != GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))))
472 error ("can't convert between vector values of different size");
473 return error_mark_node;
475 return build1 (NOP_EXPR, type, expr);
478 error ("can't convert value to a vector");
479 return convert_to_vector (type, integer_zero_node);