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(fold, case EQ_EXPR): When folding VAR++ = CONST, mask the new const

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if VAR is a bitfield reference; also for VAR--.

From-SVN: r11976
This commit is contained in:
Richard Kenner 1996-05-16 18:53:14 -04:00
parent c30ac67641
commit 30eca39133
1 changed files with 35 additions and 0 deletions
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35
gcc/fold-const.c
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@ -4428,6 +4428,24 @@ fold (expr)
constop, TREE_OPERAND (varop, 1)));
TREE_SET_CODE (varop, PREINCREMENT_EXPR);
/* If VAROP is a reference to a bitfield, we must mask
the constant by the width of the field. */
if (TREE_CODE (TREE_OPERAND (varop, 0)) == COMPONENT_REF
&& DECL_BIT_FIELD(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)))
{
int size
= TREE_INT_CST_LOW (DECL_SIZE
(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)));
newconst = fold (build (BIT_AND_EXPR,
TREE_TYPE (varop), newconst,
convert (TREE_TYPE (varop),
build_int_2 (size, 0))));
}
t = build (code, type, TREE_OPERAND (t, 0),
TREE_OPERAND (t, 1));
TREE_OPERAND (t, constopnum) = newconst;
@ -4444,6 +4462,23 @@ fold (expr)
= fold (build (MINUS_EXPR, TREE_TYPE (varop),
constop, TREE_OPERAND (varop, 1)));
TREE_SET_CODE (varop, PREDECREMENT_EXPR);
if (TREE_CODE (TREE_OPERAND (varop, 0)) == COMPONENT_REF
&& DECL_BIT_FIELD(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)))
{
int size
= TREE_INT_CST_LOW (DECL_SIZE
(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)));
newconst = fold (build (BIT_AND_EXPR,
TREE_TYPE (varop), newconst,
convert (TREE_TYPE (varop),
build_int_2 (size, 0))));
}
t = build (code, type, TREE_OPERAND (t, 0),
TREE_OPERAND (t, 1));
TREE_OPERAND (t, constopnum) = newconst;