--- /dev/null
+/* Utility routines for data type conversion for GNU C.
+ Copyright (C) 1987, 1988, 1991, 1992 Free Software Foundation, Inc.
+
+This file is part of GNU C.
+
+GNU CC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU CC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU CC; see the file COPYING. If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+
+/* These routines are somewhat language-independent utility function
+ intended to be called by the language-specific convert () functions. */
+
+#include "config.h"
+#include "tree.h"
+#include "flags.h"
+#include "convert.h"
+
+/* Convert EXPR to some pointer type TYPE.
+
+ EXPR must be pointer, integer, enumeral, or literal zero;
+ in other cases error is called. */
+
+tree
+convert_to_pointer (type, expr)
+ tree type, expr;
+{
+ register tree intype = TREE_TYPE (expr);
+ register enum tree_code form = TREE_CODE (intype);
+
+ if (integer_zerop (expr))
+ {
+ if (type == TREE_TYPE (null_pointer_node))
+ return null_pointer_node;
+ expr = build_int_2 (0, 0);
+ TREE_TYPE (expr) = type;
+ return expr;
+ }
+
+ if (form == POINTER_TYPE)
+ return build1 (NOP_EXPR, type, expr);
+
+
+ if (form == INTEGER_TYPE || form == ENUMERAL_TYPE)
+ {
+ if (type_precision (intype) == POINTER_SIZE)
+ return build1 (CONVERT_EXPR, type, expr);
+ expr = convert (type_for_size (POINTER_SIZE, 0), expr);
+ if (TYPE_MODE (TREE_TYPE (expr)) != TYPE_MODE (type))
+ /* There is supposed to be some integral type
+ that is the same width as a pointer. */
+ abort ();
+ return convert_to_pointer (type, expr);
+ }
+
+ error ("cannot convert to a pointer type");
+
+ return null_pointer_node;
+}
+
+/* Convert EXPR to some floating-point type TYPE.
+
+ EXPR must be float, integer, or enumeral;
+ in other cases error is called. */
+
+tree
+convert_to_real (type, expr)
+ tree type, expr;
+{
+ register enum tree_code form = TREE_CODE (TREE_TYPE (expr));
+
+ if (form == REAL_TYPE)
+ return build1 (flag_float_store ? CONVERT_EXPR : NOP_EXPR,
+ type, expr);
+
+ if (form == INTEGER_TYPE || form == ENUMERAL_TYPE)
+ return build1 (FLOAT_EXPR, type, expr);
+
+ if (form == POINTER_TYPE)
+ error ("pointer value used where a floating point value was expected");
+ else
+ error ("aggregate value used where a float was expected");
+
+ {
+ register tree tem = make_node (REAL_CST);
+ TREE_TYPE (tem) = type;
+ TREE_REAL_CST (tem) = REAL_VALUE_ATOF ("0.0");
+ return tem;
+ }
+}
+
+/* Convert EXPR to some integer (or enum) type TYPE.
+
+ EXPR must be pointer, integer, discrete (enum, char, or bool), or float;
+ in other cases error is called.
+
+ The result of this is always supposed to be a newly created tree node
+ not in use in any existing structure. */
+
+tree
+convert_to_integer (type, expr)
+ tree type, expr;
+{
+ register tree intype = TREE_TYPE (expr);
+ register enum tree_code form = TREE_CODE (intype);
+
+ if (form == POINTER_TYPE)
+ {
+ if (integer_zerop (expr))
+ expr = integer_zero_node;
+ else
+ expr = fold (build1 (CONVERT_EXPR,
+ type_for_size (POINTER_SIZE, 0), expr));
+ intype = TREE_TYPE (expr);
+ form = TREE_CODE (intype);
+ if (intype == type)
+ return expr;
+ }
+
+ if (form == INTEGER_TYPE || form == ENUMERAL_TYPE
+ || form == BOOLEAN_TYPE || form == CHAR_TYPE)
+ {
+ register unsigned outprec = TYPE_PRECISION (type);
+ register unsigned inprec = TYPE_PRECISION (intype);
+ register enum tree_code ex_form = TREE_CODE (expr);
+
+ /* If we are widening the type, put in an explicit conversion.
+ Similarly if we are not changing the width. However, if this is
+ a logical operation that just returns 0 or 1, we can change the
+ type of the expression (see below). */
+
+ if (TREE_CODE_CLASS (ex_form) == '<'
+ || ex_form == TRUTH_AND_EXPR || ex_form == TRUTH_ANDIF_EXPR
+ || ex_form == TRUTH_OR_EXPR || ex_form == TRUTH_ORIF_EXPR
+ || ex_form == TRUTH_XOR_EXPR || ex_form == TRUTH_NOT_EXPR)
+ {
+ TREE_TYPE (expr) = type;
+ return expr;
+ }
+ else if (outprec >= inprec)
+ return build1 (NOP_EXPR, type, expr);
+
+/* Here detect when we can distribute the truncation down past some arithmetic.
+ For example, if adding two longs and converting to an int,
+ we can equally well convert both to ints and then add.
+ For the operations handled here, such truncation distribution
+ is always safe.
+ It is desirable in these cases:
+ 1) when truncating down to full-word from a larger size
+ 2) when truncating takes no work.
+ 3) when at least one operand of the arithmetic has been extended
+ (as by C's default conversions). In this case we need two conversions
+ if we do the arithmetic as already requested, so we might as well
+ truncate both and then combine. Perhaps that way we need only one.
+
+ Note that in general we cannot do the arithmetic in a type
+ shorter than the desired result of conversion, even if the operands
+ are both extended from a shorter type, because they might overflow
+ if combined in that type. The exceptions to this--the times when
+ two narrow values can be combined in their narrow type even to
+ make a wider result--are handled by "shorten" in build_binary_op. */
+
+ switch (ex_form)
+ {
+ case RSHIFT_EXPR:
+ /* We can pass truncation down through right shifting
+ when the shift count is a nonpositive constant. */
+ if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
+ && tree_int_cst_lt (TREE_OPERAND (expr, 1), integer_one_node))
+ goto trunc1;
+ break;
+
+ case LSHIFT_EXPR:
+ /* We can pass truncation down through left shifting
+ when the shift count is a nonnegative constant. */
+ if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
+ && ! tree_int_cst_lt (TREE_OPERAND (expr, 1), integer_zero_node)
+ && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
+ {
+ /* If shift count is less than the width of the truncated type,
+ really shift. */
+ if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
+ /* In this case, shifting is like multiplication. */
+ goto trunc1;
+ else
+ /* If it is >= that width, result is zero.
+ Handling this with trunc1 would give the wrong result:
+ (int) ((long long) a << 32) is well defined (as 0)
+ but (int) a << 32 is undefined and would get a warning. */
+ return convert_to_integer (type, integer_zero_node);
+ }
+ break;
+
+ case MAX_EXPR:
+ case MIN_EXPR:
+ case MULT_EXPR:
+ {
+ tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
+ tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
+
+ /* Don't distribute unless the output precision is at least as big
+ as the actual inputs. Otherwise, the comparison of the
+ truncated values will be wrong. */
+ if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
+ && outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
+ /* If signedness of arg0 and arg1 don't match,
+ we can't necessarily find a type to compare them in. */
+ && (TREE_UNSIGNED (TREE_TYPE (arg0))
+ == TREE_UNSIGNED (TREE_TYPE (arg1))))
+ goto trunc1;
+ break;
+ }
+
+ case PLUS_EXPR:
+ case MINUS_EXPR:
+ case BIT_AND_EXPR:
+ case BIT_IOR_EXPR:
+ case BIT_XOR_EXPR:
+ case BIT_ANDTC_EXPR:
+ trunc1:
+ {
+ tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
+ tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
+
+ if (outprec >= BITS_PER_WORD
+ || TRULY_NOOP_TRUNCATION (outprec, inprec)
+ || inprec > TYPE_PRECISION (TREE_TYPE (arg0))
+ || inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
+ {
+ /* Do the arithmetic in type TYPEX,
+ then convert result to TYPE. */
+ register tree typex = type;
+
+ /* Can't do arithmetic in enumeral types
+ so use an integer type that will hold the values. */
+ if (TREE_CODE (typex) == ENUMERAL_TYPE)
+ typex = type_for_size (TYPE_PRECISION (typex),
+ TREE_UNSIGNED (typex));
+
+ /* But now perhaps TYPEX is as wide as INPREC.
+ In that case, do nothing special here.
+ (Otherwise would recurse infinitely in convert. */
+ if (TYPE_PRECISION (typex) != inprec)
+ {
+ /* Don't do unsigned arithmetic where signed was wanted,
+ or vice versa.
+ Exception: if either of the original operands were
+ unsigned then can safely do the work as unsigned.
+ And we may need to do it as unsigned
+ if we truncate to the original size. */
+ typex = ((TREE_UNSIGNED (TREE_TYPE (expr))
+ || TREE_UNSIGNED (TREE_TYPE (arg0))
+ || TREE_UNSIGNED (TREE_TYPE (arg1)))
+ ? unsigned_type (typex) : signed_type (typex));
+ return convert (type,
+ build_binary_op (ex_form,
+ convert (typex, arg0),
+ convert (typex, arg1),
+ 0));
+ }
+ }
+ }
+ break;
+
+ case NEGATE_EXPR:
+ case BIT_NOT_EXPR:
+ case ABS_EXPR:
+ {
+ register tree typex = type;
+
+ /* Can't do arithmetic in enumeral types
+ so use an integer type that will hold the values. */
+ if (TREE_CODE (typex) == ENUMERAL_TYPE)
+ typex = type_for_size (TYPE_PRECISION (typex),
+ TREE_UNSIGNED (typex));
+
+ /* But now perhaps TYPEX is as wide as INPREC.
+ In that case, do nothing special here.
+ (Otherwise would recurse infinitely in convert. */
+ if (TYPE_PRECISION (typex) != inprec)
+ {
+ /* Don't do unsigned arithmetic where signed was wanted,
+ or vice versa. */
+ typex = (TREE_UNSIGNED (TREE_TYPE (expr))
+ ? unsigned_type (typex) : signed_type (typex));
+ return convert (type,
+ build_unary_op (ex_form,
+ convert (typex, TREE_OPERAND (expr, 0)),
+ 1));
+ }
+ }
+
+ case NOP_EXPR:
+ /* If truncating after truncating, might as well do all at once.
+ If truncating after extending, we may get rid of wasted work. */
+ return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
+
+ case COND_EXPR:
+ /* Can treat the two alternative values like the operands
+ of an arithmetic expression. */
+ {
+ tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
+ tree arg2 = get_unwidened (TREE_OPERAND (expr, 2), type);
+
+ if (outprec >= BITS_PER_WORD
+ || TRULY_NOOP_TRUNCATION (outprec, inprec)
+ || inprec > TYPE_PRECISION (TREE_TYPE (arg1))
+ || inprec > TYPE_PRECISION (TREE_TYPE (arg2)))
+ {
+ /* Do the arithmetic in type TYPEX,
+ then convert result to TYPE. */
+ register tree typex = type;
+
+ /* Can't do arithmetic in enumeral types
+ so use an integer type that will hold the values. */
+ if (TREE_CODE (typex) == ENUMERAL_TYPE)
+ typex = type_for_size (TYPE_PRECISION (typex),
+ TREE_UNSIGNED (typex));
+
+ /* But now perhaps TYPEX is as wide as INPREC.
+ In that case, do nothing special here.
+ (Otherwise would recurse infinitely in convert. */
+ if (TYPE_PRECISION (typex) != inprec)
+ {
+ /* Don't do unsigned arithmetic where signed was wanted,
+ or vice versa. */
+ typex = (TREE_UNSIGNED (TREE_TYPE (expr))
+ ? unsigned_type (typex) : signed_type (typex));
+ return convert (type,
+ fold (build (COND_EXPR, typex,
+ TREE_OPERAND (expr, 0),
+ convert (typex, arg1),
+ convert (typex, arg2))));
+ }
+ else
+ /* It is sometimes worthwhile
+ to push the narrowing down through the conditional. */
+ return fold (build (COND_EXPR, type,
+ TREE_OPERAND (expr, 0),
+ convert (type, TREE_OPERAND (expr, 1)),
+ convert (type, TREE_OPERAND (expr, 2))));
+ }
+ }
+
+ }
+
+ return build1 (NOP_EXPR, type, expr);
+ }
+
+ if (form == REAL_TYPE)
+ return build1 (FIX_TRUNC_EXPR, type, expr);
+
+ error ("aggregate value used where an integer was expected");
+
+ {
+ register tree tem = build_int_2 (0, 0);
+ TREE_TYPE (tem) = type;
+ return tem;
+ }
+}
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