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(force_to_mode, case ASHIFTRT): Properly handle mask wider than

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HOST_WIDE_INT.

From-SVN: r10534
This commit is contained in:
Richard Kenner 1995-10-27 15:08:26 -04:00
parent bcbed70984
commit b69960ac72
1 changed files with 24 additions and 2 deletions
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26
gcc/combine.c
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@ -6035,8 +6035,30 @@ force_to_mode (x, mode, mask, reg, just_select)
{
int i = -1;
nonzero = GET_MODE_MASK (GET_MODE (x));
nonzero >>= INTVAL (XEXP (x, 1));
/* If the considered data is wider then HOST_WIDE_INT, we can't
represent a mask for all its bits in a single scalar.
But we only care about the lower bits, so calculate these. */
if (GET_MODE_SIZE (GET_MODE (x)) > sizeof (HOST_WIDE_INT))
{
nonzero = ~(HOST_WIDE_INT)0;
/* GET_MODE_BITSIZE (GET_MODE (x)) - INTVAL (XEXP (x, 1))
is the number of bits a full-width mask would have set.
We need only shift if these are fewer than nonzero can
hold. If not, we must keep all bits set in nonzero. */
if (GET_MODE_BITSIZE (GET_MODE (x)) - INTVAL (XEXP (x, 1))
< HOST_BITS_PER_WIDE_INT)
nonzero >>= INTVAL (XEXP (x, 1))
+ HOST_BITS_PER_WIDE_INT
- GET_MODE_BITSIZE (GET_MODE (x)) ;
}
else
{
nonzero = GET_MODE_MASK (GET_MODE (x));
nonzero >>= INTVAL (XEXP (x, 1));
}
if ((mask & ~ nonzero) == 0
|| (i = exact_log2 (mask)) >= 0)