480 lines
14 KiB
C
480 lines
14 KiB
C
/* Utility routines for data type conversion for GNU C.
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Copyright (C) 1987, 1988, 1991, 1992, 1993, 1994, 1995, 1997,
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1998 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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/* These routines are somewhat language-independent utility function
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intended to be called by the language-specific convert () functions. */
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#include "config.h"
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#include "system.h"
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#include "tree.h"
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#include "flags.h"
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#include "convert.h"
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#include "toplev.h"
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/* Convert EXPR to some pointer or reference type TYPE.
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EXPR must be pointer, reference, integer, enumeral, or literal zero;
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in other cases error is called. */
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tree
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convert_to_pointer (type, expr)
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tree type, expr;
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{
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if (integer_zerop (expr))
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{
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expr = build_int_2 (0, 0);
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TREE_TYPE (expr) = type;
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return expr;
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}
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switch (TREE_CODE (TREE_TYPE (expr)))
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{
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case POINTER_TYPE:
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case REFERENCE_TYPE:
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return build1 (NOP_EXPR, type, expr);
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case INTEGER_TYPE:
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case ENUMERAL_TYPE:
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case BOOLEAN_TYPE:
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case CHAR_TYPE:
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if (TYPE_PRECISION (TREE_TYPE (expr)) == POINTER_SIZE)
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return build1 (CONVERT_EXPR, type, expr);
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return
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convert_to_pointer (type,
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convert (type_for_size (POINTER_SIZE, 0), expr));
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default:
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error ("cannot convert to a pointer type");
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return convert_to_pointer (type, integer_zero_node);
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}
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}
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/* Convert EXPR to some floating-point type TYPE.
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EXPR must be float, integer, or enumeral;
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in other cases error is called. */
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tree
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convert_to_real (type, expr)
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tree type, expr;
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{
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switch (TREE_CODE (TREE_TYPE (expr)))
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{
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case REAL_TYPE:
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return build1 (flag_float_store ? CONVERT_EXPR : NOP_EXPR,
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type, expr);
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case INTEGER_TYPE:
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case ENUMERAL_TYPE:
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case BOOLEAN_TYPE:
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case CHAR_TYPE:
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return build1 (FLOAT_EXPR, type, expr);
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case COMPLEX_TYPE:
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return convert (type,
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fold (build1 (REALPART_EXPR,
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TREE_TYPE (TREE_TYPE (expr)), expr)));
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case POINTER_TYPE:
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case REFERENCE_TYPE:
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error ("pointer value used where a floating point value was expected");
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return convert_to_real (type, integer_zero_node);
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default:
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error ("aggregate value used where a float was expected");
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return convert_to_real (type, integer_zero_node);
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}
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}
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/* Convert EXPR to some integer (or enum) type TYPE.
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EXPR must be pointer, integer, discrete (enum, char, or bool), float, or
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vector; in other cases error is called.
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The result of this is always supposed to be a newly created tree node
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not in use in any existing structure. */
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tree
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convert_to_integer (type, expr)
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tree type, expr;
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{
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enum tree_code ex_form = TREE_CODE (expr);
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tree intype = TREE_TYPE (expr);
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unsigned int inprec = TYPE_PRECISION (intype);
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unsigned int outprec = TYPE_PRECISION (type);
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/* An INTEGER_TYPE cannot be incomplete, but an ENUMERAL_TYPE can
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be. Consider `enum E = { a, b = (enum E) 3 };'. */
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if (!COMPLETE_TYPE_P (type))
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{
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error ("conversion to incomplete type");
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return error_mark_node;
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}
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switch (TREE_CODE (intype))
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{
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case POINTER_TYPE:
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case REFERENCE_TYPE:
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if (integer_zerop (expr))
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expr = integer_zero_node;
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else
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expr = fold (build1 (CONVERT_EXPR,
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type_for_size (POINTER_SIZE, 0), expr));
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return convert_to_integer (type, expr);
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case INTEGER_TYPE:
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case ENUMERAL_TYPE:
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case BOOLEAN_TYPE:
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case CHAR_TYPE:
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/* If this is a logical operation, which just returns 0 or 1, we can
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change the type of the expression. For some logical operations,
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we must also change the types of the operands to maintain type
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correctness. */
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if (TREE_CODE_CLASS (ex_form) == '<')
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{
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TREE_TYPE (expr) = type;
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return expr;
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}
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else if (ex_form == TRUTH_AND_EXPR || ex_form == TRUTH_ANDIF_EXPR
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|| ex_form == TRUTH_OR_EXPR || ex_form == TRUTH_ORIF_EXPR
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|| ex_form == TRUTH_XOR_EXPR)
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{
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TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0));
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TREE_OPERAND (expr, 1) = convert (type, TREE_OPERAND (expr, 1));
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TREE_TYPE (expr) = type;
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return expr;
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}
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else if (ex_form == TRUTH_NOT_EXPR)
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{
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TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0));
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TREE_TYPE (expr) = type;
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return expr;
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}
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/* If we are widening the type, put in an explicit conversion.
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Similarly if we are not changing the width. After this, we know
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we are truncating EXPR. */
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else if (outprec >= inprec)
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return build1 (NOP_EXPR, type, expr);
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/* If TYPE is an enumeral type or a type with a precision less
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than the number of bits in its mode, do the conversion to the
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type corresponding to its mode, then do a nop conversion
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to TYPE. */
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else if (TREE_CODE (type) == ENUMERAL_TYPE
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|| outprec != GET_MODE_BITSIZE (TYPE_MODE (type)))
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return build1 (NOP_EXPR, type,
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convert (type_for_mode (TYPE_MODE (type),
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TREE_UNSIGNED (type)),
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expr));
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/* Here detect when we can distribute the truncation down past some
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arithmetic. For example, if adding two longs and converting to an
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int, we can equally well convert both to ints and then add.
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For the operations handled here, such truncation distribution
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is always safe.
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It is desirable in these cases:
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1) when truncating down to full-word from a larger size
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2) when truncating takes no work.
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3) when at least one operand of the arithmetic has been extended
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(as by C's default conversions). In this case we need two conversions
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if we do the arithmetic as already requested, so we might as well
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truncate both and then combine. Perhaps that way we need only one.
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Note that in general we cannot do the arithmetic in a type
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shorter than the desired result of conversion, even if the operands
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are both extended from a shorter type, because they might overflow
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if combined in that type. The exceptions to this--the times when
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two narrow values can be combined in their narrow type even to
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make a wider result--are handled by "shorten" in build_binary_op. */
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switch (ex_form)
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{
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case RSHIFT_EXPR:
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/* We can pass truncation down through right shifting
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when the shift count is a nonpositive constant. */
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if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
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&& tree_int_cst_lt (TREE_OPERAND (expr, 1),
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convert (TREE_TYPE (TREE_OPERAND (expr, 1)),
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integer_one_node)))
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goto trunc1;
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break;
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case LSHIFT_EXPR:
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/* We can pass truncation down through left shifting
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when the shift count is a nonnegative constant. */
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if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
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&& tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0
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&& TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
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{
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/* If shift count is less than the width of the truncated type,
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really shift. */
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if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type)))
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/* In this case, shifting is like multiplication. */
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goto trunc1;
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else
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{
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/* If it is >= that width, result is zero.
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Handling this with trunc1 would give the wrong result:
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(int) ((long long) a << 32) is well defined (as 0)
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but (int) a << 32 is undefined and would get a
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warning. */
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tree t = convert_to_integer (type, integer_zero_node);
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/* If the original expression had side-effects, we must
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preserve it. */
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if (TREE_SIDE_EFFECTS (expr))
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return build (COMPOUND_EXPR, type, expr, t);
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else
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return t;
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}
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}
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break;
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case MAX_EXPR:
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case MIN_EXPR:
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case MULT_EXPR:
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{
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tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
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tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
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/* Don't distribute unless the output precision is at least as big
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as the actual inputs. Otherwise, the comparison of the
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truncated values will be wrong. */
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if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
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&& outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
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/* If signedness of arg0 and arg1 don't match,
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we can't necessarily find a type to compare them in. */
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&& (TREE_UNSIGNED (TREE_TYPE (arg0))
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== TREE_UNSIGNED (TREE_TYPE (arg1))))
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goto trunc1;
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break;
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}
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case PLUS_EXPR:
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case MINUS_EXPR:
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case BIT_AND_EXPR:
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case BIT_IOR_EXPR:
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case BIT_XOR_EXPR:
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case BIT_ANDTC_EXPR:
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trunc1:
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{
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tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
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tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
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if (outprec >= BITS_PER_WORD
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|| TRULY_NOOP_TRUNCATION (outprec, inprec)
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|| inprec > TYPE_PRECISION (TREE_TYPE (arg0))
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|| inprec > TYPE_PRECISION (TREE_TYPE (arg1)))
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{
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/* Do the arithmetic in type TYPEX,
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then convert result to TYPE. */
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tree typex = type;
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/* Can't do arithmetic in enumeral types
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so use an integer type that will hold the values. */
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if (TREE_CODE (typex) == ENUMERAL_TYPE)
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typex = type_for_size (TYPE_PRECISION (typex),
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TREE_UNSIGNED (typex));
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/* But now perhaps TYPEX is as wide as INPREC.
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In that case, do nothing special here.
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(Otherwise would recurse infinitely in convert. */
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if (TYPE_PRECISION (typex) != inprec)
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{
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/* Don't do unsigned arithmetic where signed was wanted,
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or vice versa.
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Exception: if both of the original operands were
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unsigned then can safely do the work as unsigned.
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And we may need to do it as unsigned
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if we truncate to the original size. */
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typex = ((TREE_UNSIGNED (TREE_TYPE (expr))
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|| (TREE_UNSIGNED (TREE_TYPE (arg0))
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&& TREE_UNSIGNED (TREE_TYPE (arg1))))
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? unsigned_type (typex) : signed_type (typex));
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return convert (type,
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fold (build (ex_form, typex,
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convert (typex, arg0),
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convert (typex, arg1),
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0)));
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}
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}
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}
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break;
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case NEGATE_EXPR:
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case BIT_NOT_EXPR:
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/* This is not correct for ABS_EXPR,
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since we must test the sign before truncation. */
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{
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tree typex = type;
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/* Can't do arithmetic in enumeral types
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so use an integer type that will hold the values. */
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if (TREE_CODE (typex) == ENUMERAL_TYPE)
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typex = type_for_size (TYPE_PRECISION (typex),
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TREE_UNSIGNED (typex));
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/* But now perhaps TYPEX is as wide as INPREC.
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In that case, do nothing special here.
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(Otherwise would recurse infinitely in convert. */
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if (TYPE_PRECISION (typex) != inprec)
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{
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/* Don't do unsigned arithmetic where signed was wanted,
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or vice versa. */
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typex = (TREE_UNSIGNED (TREE_TYPE (expr))
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? unsigned_type (typex) : signed_type (typex));
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return convert (type,
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fold (build1 (ex_form, typex,
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convert (typex,
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TREE_OPERAND (expr, 0)))));
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}
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}
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case NOP_EXPR:
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/* If truncating after truncating, might as well do all at once.
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If truncating after extending, we may get rid of wasted work. */
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return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type));
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case COND_EXPR:
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/* It is sometimes worthwhile to push the narrowing down through
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the conditional and never loses. */
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return fold (build (COND_EXPR, type, TREE_OPERAND (expr, 0),
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convert (type, TREE_OPERAND (expr, 1)),
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convert (type, TREE_OPERAND (expr, 2))));
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default:
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break;
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}
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return build1 (NOP_EXPR, type, expr);
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case REAL_TYPE:
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return build1 (FIX_TRUNC_EXPR, type, expr);
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case COMPLEX_TYPE:
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return convert (type,
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fold (build1 (REALPART_EXPR,
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TREE_TYPE (TREE_TYPE (expr)), expr)));
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case VECTOR_TYPE:
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if (GET_MODE_SIZE (TYPE_MODE (type))
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!= GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))))
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{
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error ("can't convert between vector values of different size");
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return error_mark_node;
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}
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return build1 (NOP_EXPR, type, expr);
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default:
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error ("aggregate value used where an integer was expected");
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return convert (type, integer_zero_node);
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}
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}
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/* Convert EXPR to the complex type TYPE in the usual ways. */
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tree
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convert_to_complex (type, expr)
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tree type, expr;
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{
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tree subtype = TREE_TYPE (type);
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switch (TREE_CODE (TREE_TYPE (expr)))
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{
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case REAL_TYPE:
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case INTEGER_TYPE:
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case ENUMERAL_TYPE:
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case BOOLEAN_TYPE:
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case CHAR_TYPE:
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return build (COMPLEX_EXPR, type, convert (subtype, expr),
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convert (subtype, integer_zero_node));
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case COMPLEX_TYPE:
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{
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tree elt_type = TREE_TYPE (TREE_TYPE (expr));
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if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype))
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return expr;
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else if (TREE_CODE (expr) == COMPLEX_EXPR)
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return fold (build (COMPLEX_EXPR,
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type,
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convert (subtype, TREE_OPERAND (expr, 0)),
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convert (subtype, TREE_OPERAND (expr, 1))));
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else
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{
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expr = save_expr (expr);
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return
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fold (build (COMPLEX_EXPR,
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type, convert (subtype,
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fold (build1 (REALPART_EXPR,
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TREE_TYPE (TREE_TYPE (expr)),
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expr))),
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convert (subtype,
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fold (build1 (IMAGPART_EXPR,
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TREE_TYPE (TREE_TYPE (expr)),
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expr)))));
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}
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}
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case POINTER_TYPE:
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case REFERENCE_TYPE:
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error ("pointer value used where a complex was expected");
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return convert_to_complex (type, integer_zero_node);
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default:
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error ("aggregate value used where a complex was expected");
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return convert_to_complex (type, integer_zero_node);
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}
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}
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/* Convert EXPR to the vector type TYPE in the usual ways. */
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tree
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convert_to_vector (type, expr)
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tree type, expr;
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{
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switch (TREE_CODE (TREE_TYPE (expr)))
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{
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case INTEGER_TYPE:
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case VECTOR_TYPE:
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if (GET_MODE_SIZE (TYPE_MODE (type))
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!= GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))))
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{
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error ("can't convert between vector values of different size");
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return error_mark_node;
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}
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return build1 (NOP_EXPR, type, expr);
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default:
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error ("can't convert value to a vector");
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return convert_to_vector (type, integer_zero_node);
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}
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}
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