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(simplify_and_const_int): Never consider bits outside of MODE. 

From-SVN: r3398
This commit is contained in:
Richard Kenner 1993-01-31 17:44:48 -05:00
parent 8935266327
commit fc06d7aaee
1 changed files with 5 additions and 2 deletions
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7
gcc/combine.c
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@ -5899,8 +5899,11 @@ simplify_and_const_int (x, mode, varop, constop)
if (GET_CODE (varop) == CONST_INT)
return GEN_INT (constop & INTVAL (varop));
/* See what bits may be nonzero in VAROP. */
nonzero = nonzero_bits (varop, mode);
/* See what bits may be nonzero in VAROP. Unlike the general case of
a call to nonzero_bits, here we don't care about bits outside
MODE. */
nonzero = nonzero_bits (varop, mode) & GET_MODE_MASK (mode);
/* Turn off all bits in the constant that are known to already be zero.
Thus, if the AND isn't needed at all, we will have CONSTOP == NONZERO_BITS