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fold-const.c (fold): Optimize ~X|X and X|~X as -1.

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* fold-const.c (fold) <BIT_IOR_EXPR>: Optimize ~X|X and X|~X as -1.
	<BIT_XOR_EXPR>: Optimize ~X|X and X|~X as -1.
	<BIT_AND_EXPR>: Optimize ~X&X and X&~X as 0.
	<TRUTH_AND_EXPR, TRUTH_ANDIF_EXPR>: Optimize !X&&X and X&&!X as false.
        <TRUTH_OR_EXPR, TRUTH_ORIF_EXPR>: Optimize !X||X and !X||X as true.
	<TRUTH_XOR_EXPR>: Optimize !X^X and X^X! as true.  Now that
	TRUTH_XOR_EXPR is a commutative tree code, don't test whether arg0
	is a constant.

	* gcc.dg/20040527-1.c: New test case.

From-SVN: r83733
This commit is contained in:
Roger Sayle 2004-06-27 15:23:46 +00:00 committed by Roger Sayle
parent 73bbafe578
commit 64b663f8bd
4 changed files with 141 additions and 6 deletions
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11
gcc/ChangeLog
View File

@ -1,3 +1,14 @@
2004-06-27 Roger Sayle <roger@eyesopen.com>
* fold-const.c (fold) <BIT_IOR_EXPR>: Optimize ~X|X and X|~X as -1.
<BIT_XOR_EXPR>: Optimize ~X|X and X|~X as -1.
<BIT_AND_EXPR>: Optimize ~X&X and X&~X as 0.
<TRUTH_AND_EXPR, TRUTH_ANDIF_EXPR>: Optimize !X&&X and X&&!X as false.
<TRUTH_OR_EXPR, TRUTH_ORIF_EXPR>: Optimize !X||X and !X||X as true.
<TRUTH_XOR_EXPR>: Optimize !X^X and X^X! as true. Now that
TRUTH_XOR_EXPR is a commutative tree code, don't test whether arg0
is a constant.
2004-06-26 Andrew Pinski <pinskia@physics.uc.edu>
PR 13334

90
gcc/fold-const.c
View File

@ -7185,6 +7185,27 @@ fold (tree expr)
return non_lvalue (fold_convert (type, arg0));
if (operand_equal_p (arg0, arg1, 0))
return non_lvalue (fold_convert (type, arg0));
/* ~X | X is -1. */
if (TREE_CODE (arg0) == BIT_NOT_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
{
t1 = build_int_2 (-1, -1);
TREE_TYPE (t1) = type;
force_fit_type (t1, 0);
return omit_one_operand (type, t1, arg1);
}
/* X | ~X is -1. */
if (TREE_CODE (arg1) == BIT_NOT_EXPR
&& operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
{
t1 = build_int_2 (-1, -1);
TREE_TYPE (t1) = type;
force_fit_type (t1, 0);
return omit_one_operand (type, t1, arg0);
}
t1 = distribute_bit_expr (code, type, arg0, arg1);
if (t1 != NULL_TREE)
return t1;
@ -7216,6 +7237,26 @@ fold (tree expr)
if (operand_equal_p (arg0, arg1, 0))
return omit_one_operand (type, integer_zero_node, arg0);
/* ~X ^ X is -1. */
if (TREE_CODE (arg0) == BIT_NOT_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
{
t1 = build_int_2 (-1, -1);
TREE_TYPE (t1) = type;
force_fit_type (t1, 0);
return omit_one_operand (type, t1, arg1);
}
/* X ^ ~X is -1. */
if (TREE_CODE (arg1) == BIT_NOT_EXPR
&& operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
{
t1 = build_int_2 (-1, -1);
TREE_TYPE (t1) = type;
force_fit_type (t1, 0);
return omit_one_operand (type, t1, arg0);
}
/* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
with a constant, and the two constants have no bits in common,
we should treat this as a BIT_IOR_EXPR since this may produce more
@ -7243,6 +7284,17 @@ fold (tree expr)
return omit_one_operand (type, arg1, arg0);
if (operand_equal_p (arg0, arg1, 0))
return non_lvalue (fold_convert (type, arg0));
/* ~X & X is always zero. */
if (TREE_CODE (arg0) == BIT_NOT_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
return omit_one_operand (type, integer_zero_node, arg1);
/* X & ~X is always zero. */
if (TREE_CODE (arg1) == BIT_NOT_EXPR
&& operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
return omit_one_operand (type, integer_zero_node, arg0);
t1 = distribute_bit_expr (code, type, arg0, arg1);
if (t1 != NULL_TREE)
return t1;
@ -7625,6 +7677,15 @@ fold (tree expr)
if (integer_zerop (arg0))
return omit_one_operand (type, arg0, arg1);
/* !X && X is always false. */
if (TREE_CODE (arg0) == TRUTH_NOT_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
return omit_one_operand (type, integer_zero_node, arg1);
/* X && !X is always false. */
if (TREE_CODE (arg1) == TRUTH_NOT_EXPR
&& operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
return omit_one_operand (type, integer_zero_node, arg0);
truth_andor:
/* We only do these simplifications if we are optimizing. */
if (!optimize)
@ -7712,22 +7773,39 @@ fold (tree expr)
TRUTH_OR_EXPR. */
if (TREE_CODE (arg0) == INTEGER_CST && ! integer_zerop (arg0))
return omit_one_operand (type, arg0, arg1);
/* !X || X is always true. */
if (TREE_CODE (arg0) == TRUTH_NOT_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
return omit_one_operand (type, integer_one_node, arg1);
/* X || !X is always true. */
if (TREE_CODE (arg1) == TRUTH_NOT_EXPR
&& operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
return omit_one_operand (type, integer_one_node, arg0);
goto truth_andor;
case TRUTH_XOR_EXPR:
/* If either arg is constant zero, drop it. */
if (integer_zerop (arg0))
return non_lvalue (fold_convert (type, arg1));
/* If the second arg is constant zero, drop it. */
if (integer_zerop (arg1))
return non_lvalue (fold_convert (type, arg0));
/* If either arg is constant true, this is a logical inversion. */
if (integer_onep (arg0))
return non_lvalue (fold_convert (type, invert_truthvalue (arg1)));
/* If the second arg is constant true, this is a logical inversion. */
if (integer_onep (arg1))
return non_lvalue (fold_convert (type, invert_truthvalue (arg0)));
/* Identical arguments cancel to zero. */
if (operand_equal_p (arg0, arg1, 0))
return omit_one_operand (type, integer_zero_node, arg0);
/* !X ^ X is always true. */
if (TREE_CODE (arg0) == TRUTH_NOT_EXPR
&& operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0))
return omit_one_operand (type, integer_one_node, arg1);
/* X ^ !X is always true. */
if (TREE_CODE (arg1) == TRUTH_NOT_EXPR
&& operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0))
return omit_one_operand (type, integer_one_node, arg0);
return t;
case EQ_EXPR:

4
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,7 @@
2004-06-27 Roger Sayle <roger@eyesopen.com>
* gcc.dg/20040527-1.c: New test case.
2004-06-26 Bud Davis <bdavis9659@comcast.net>
PR gfortran/pr16196

42
gcc/testsuite/gcc.dg/20040627-1.c Normal file
View File

@ -0,0 +1,42 @@
/* { dg-do link } */
/* { dg-options "-O2" } */
extern void link_error (void);
void test(int x)
{
if ((x & ~x) != 0)
link_error ();
if ((~x & x) != 0)
link_error ();
if ((x ^ ~x) != -1)
link_error ();
if ((~x ^ x) != -1)
link_error ();
if ((x | ~x) != -1)
link_error ();
if ((~x | x) != -1)
link_error ();
if (x && !x)
link_error ();
if (!x && x)
link_error ();
if (!(x || !x))
link_error ();
if (!(!x || x))
link_error ();
}
int main()
{
test (0);
test (1);
test (-1);
return 0;
}