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* fold-const.c (fold): Fold some comparisons of bit operations. 

From-SVN: r70009
This commit is contained in:
Zdenek Dvorak 2003-07-31 20:29:34 +02:00 committed by Zdenek Dvorak
parent 049d2251b8
commit b7de586461
2 changed files with 32 additions and 0 deletions
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4
gcc/ChangeLog
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@ -1,3 +1,7 @@
2003-07-31 Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz>
* fold-const.c (fold): Fold some comparisons of bit operations.
Thu Jul 31 19:49:53 CEST 2003 Jan Hubicka <jh@suse.cz>
* cgraph.c (create_edge): Fix typo.

28
gcc/fold-const.c
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@ -7182,6 +7182,34 @@ fold (tree expr)
if (tem)
return tem;
/* If we have (A & C) == D where D & ~C != 0, convert this into 0.
Similarly for NE_EXPR. */
if ((code == EQ_EXPR || code == NE_EXPR)
&& TREE_CODE (arg0) == BIT_AND_EXPR
&& TREE_CODE (arg1) == INTEGER_CST
&& TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST)
{
tree dandnotc = fold (build (BIT_ANDTC_EXPR, TREE_TYPE (arg0),
arg1, TREE_OPERAND (arg0, 1)));
tree rslt = code == EQ_EXPR ? integer_zero_node : integer_one_node;
if (!integer_zerop (dandnotc))
return omit_one_operand (type, rslt, arg0);
}
/* If we have (A | C) == D where C & ~D != 0, convert this into 0.
Similarly for NE_EXPR. */
if ((code == EQ_EXPR || code == NE_EXPR)
&& TREE_CODE (arg0) == BIT_IOR_EXPR
&& TREE_CODE (arg1) == INTEGER_CST
&& TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST)
{
tree candnotd = fold (build (BIT_ANDTC_EXPR, TREE_TYPE (arg0),
TREE_OPERAND (arg0, 1), arg1));
tree rslt = code == EQ_EXPR ? integer_zero_node : integer_one_node;
if (!integer_zerop (candnotd))
return omit_one_operand (type, rslt, arg0);
}
/* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
and similarly for >= into !=. */
if ((code == LT_EXPR || code == GE_EXPR)