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(invert_truthvalue, case TRUTH_XOR_EXPR): New case.

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(fold, case TRUTH_XOR_EXPR): New case.
(fold, case TRUTH_OR_EXPR, TRUTH_AND_EXPR): Check for second operand
of appropriate value to determine result whether or not first operand
is a constant.

From-SVN: r2997
This commit is contained in:
Richard Kenner 1992-12-30 06:13:24 -05:00
parent f7c8fb3f49
commit 772447c5cf
1 changed files with 36 additions and 7 deletions
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43
gcc/fold-const.c
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@ -2034,6 +2034,20 @@ invert_truthvalue (arg)
invert_truthvalue (TREE_OPERAND (arg, 0)),
invert_truthvalue (TREE_OPERAND (arg, 1)));
case TRUTH_XOR_EXPR:
/* Here we can invert either operand. We invert the first operand
unless the second operand is a TRUTH_NOT_EXPR in which case our
result is the XOR of the first operand with the inside of the
negation of the second operand. */
if (TREE_CODE (TREE_OPERAND (arg, 1)) == TRUTH_NOT_EXPR)
return build (TRUTH_XOR_EXPR, type, TREE_OPERAND (arg, 0),
TREE_OPERAND (TREE_OPERAND (arg, 1), 0));
else
return build (TRUTH_XOR_EXPR, type,
invert_truthvalue (TREE_OPERAND (arg, 0)),
TREE_OPERAND (arg, 1));
case TRUTH_ANDIF_EXPR:
return build (TRUTH_ORIF_EXPR, type,
invert_truthvalue (TREE_OPERAND (arg, 0)),
@ -3697,7 +3711,7 @@ fold (expr)
and their values must be 0 or 1.
("true" is a fixed value perhaps depending on the language.) */
/* If first arg is constant zero, return it. */
if (TREE_CODE (arg0) == INTEGER_CST && integer_zerop (arg0))
if (integer_zerop (arg0))
return arg0;
case TRUTH_AND_EXPR:
/* If either arg is constant true, drop it. */
@ -3705,9 +3719,10 @@ fold (expr)
return non_lvalue (arg1);
if (TREE_CODE (arg1) == INTEGER_CST && ! integer_zerop (arg1))
return non_lvalue (arg0);
/* Both known to be zero => return zero. */
if (TREE_CODE (arg0) == INTEGER_CST && TREE_CODE (arg1) == INTEGER_CST)
return arg0;
/* If second arg is constant zero, result is zero, but first arg
must be evaluated. */
if (integer_zerop (arg1))
return omit_one_operand (type, arg1, arg0);
truth_andor:
/* Check for the possibility of merging component references. If our
@ -3742,11 +3757,25 @@ fold (expr)
return non_lvalue (arg1);
if (TREE_CODE (arg1) == INTEGER_CST && integer_zerop (arg1))
return non_lvalue (arg0);
/* Both known to be true => return true. */
if (TREE_CODE (arg0) == INTEGER_CST && TREE_CODE (arg1) == INTEGER_CST)
return arg0;
/* If second arg is constant true, result is true, but we must
evaluate first arg. */
if (TREE_CODE (arg1) == INTEGER_CST && ! integer_zerop (arg1))
return omit_one_operand (type, arg1, arg0);
goto truth_andor;
case TRUTH_XOR_EXPR:
/* If either arg is constant zero, drop it. */
if (integer_zerop (arg0))
return non_lvalue (arg1);
if (integer_zerop (arg1))
return non_lvalue (arg0);
/* If either arg is constant true, this is a logical inversion. */
if (integer_onep (arg0))
return non_lvalue (invert_truthvalue (arg1));
if (integer_onep (arg1))
return non_lvalue (invert_truthvalue (arg0));
break;
case EQ_EXPR:
case NE_EXPR:
case LT_EXPR: