Initial revision

From-SVN: r3161

2 files changed, 373 insertions, 0 deletions

diff --git a/gcc/convert.c b/gcc/convert.c
new file mode 100644
index 0000000..c67f510
--- /dev/null
+++ b/gcc/convert.c
@@ -0,0 +1,370 @@
+/* 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;
+  }
+}
diff --git a/gcc/convert.h b/gcc/convert.h
new file mode 100644
index 0000000..5e54da3
--- /dev/null
+++ b/gcc/convert.h
@@ -0,0 +1,3 @@
+extern tree convert_to_integer PROTO ((tree, tree));
+extern tree convert_to_pointer PROTO ((tree, tree));
+extern tree convert_to_real PROTO ((tree, tree));