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tree.c (save_expr): Allow either side of a dyadic operand to be constant.

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* tree.c (save_expr): Allow either side of a dyadic operand to be
	constant.

	* doc/portability.texi (portability): Update portability goals.

From-SVN: r60435
This commit is contained in:
Nathan Sidwell 2002-12-23 14:43:28 +00:00 committed by Nathan Sidwell
parent 1df7e439e1
commit 0c685f1256
3 changed files with 32 additions and 12 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2002-12-22 Nathan Sidwell <nathan@codesourcery.com>
* tree.c (save_expr): Allow either side of a dyadic operand to be
constant.
* doc/portability.texi (portability): Update portability goals.
2002-12-23 Kazu Hirata <kazu@cs.umass.edu>
* config/h8300/h8300.c (output_a_shift): Remove unused code.

11
gcc/doc/portability.texi
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@ -1,5 +1,5 @@
@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
@c 1999, 2000, 2001 Free Software Foundation, Inc.
@c 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
@ -8,10 +8,11 @@
@cindex portability
@cindex GCC and portability
The main goal of GCC was to make a good, fast compiler for machines in
the class that the GNU system aims to run on: 32-bit machines that address
8-bit bytes and have several general registers. Elegance, theoretical
power and simplicity are only secondary.
GCC itself aims to be portable to any machine where @code{int} is at least
a 32-bit type. It aims to target machines with a flat (non-segmented) byte
addressed data address space (the code address space can be separate).
Target ABIs may have 8, 16, 32 or 64-bit @code{int} type. @code{char}
can be wider than 8 bits.
GCC gets most of the information about the target machine from a machine
description which gives an algebraic formula for each of the machine's

26
gcc/tree.c
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@ -1363,12 +1363,23 @@ save_expr (expr)
a constant, it will be more efficient to not make another SAVE_EXPR since
it will allow better simplification and GCSE will be able to merge the
computations if they actualy occur. */
for (inner = t;
(TREE_CODE_CLASS (TREE_CODE (inner)) == '1'
|| (TREE_CODE_CLASS (TREE_CODE (inner)) == '2'
&& TREE_CONSTANT (TREE_OPERAND (inner, 1))));
inner = TREE_OPERAND (inner, 0))
;
inner = t;
while (1)
{
if (TREE_CODE_CLASS (TREE_CODE (inner)) == '1')
inner = TREE_OPERAND (inner, 0);
else if (TREE_CODE_CLASS (TREE_CODE (inner)) == '2')
{
if (TREE_CONSTANT (TREE_OPERAND (inner, 1)))
inner = TREE_OPERAND (inner, 0);
else if (TREE_CONSTANT (TREE_OPERAND (inner, 0)))
inner = TREE_OPERAND (inner, 1);
else
break;
}
else
break;
}
/* If the tree evaluates to a constant, then we don't want to hide that
fact (i.e. this allows further folding, and direct checks for constants).
@ -1377,7 +1388,8 @@ save_expr (expr)
literal node. */
if (TREE_CONSTANT (inner)
|| (TREE_READONLY (inner) && ! TREE_SIDE_EFFECTS (inner))
|| TREE_CODE (inner) == SAVE_EXPR || TREE_CODE (inner) == ERROR_MARK)
|| TREE_CODE (inner) == SAVE_EXPR
|| TREE_CODE (inner) == ERROR_MARK)
return t;
/* If T contains a PLACEHOLDER_EXPR, we must evaluate it each time, since