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(min_precision): Move from c-decl.c 

From-SVN: r8020
This commit is contained in:
Jason Merrill 1994-09-02 23:40:51 +00:00
parent 8294accf6d
commit 6acfe908e3
1 changed files with 31 additions and 0 deletions
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31
gcc/c-common.c
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@ -1346,6 +1346,37 @@ type_for_mode (mode, unsignedp)
return 0;
}
/* Return the minimum number of bits needed to represent VALUE in a
signed or unsigned type, UNSIGNEDP says which. */
int
min_precision (value, unsignedp)
tree value;
int unsignedp;
{
int log;
/* If the value is negative, compute its negative minus 1. The latter
adjustment is because the absolute value of the largest negative value
is one larger than the largest positive value. This is equivalent to
a bit-wise negation, so use that operation instead. */
if (tree_int_cst_sgn (value) < 0)
value = fold (build1 (BIT_NOT_EXPR, TREE_TYPE (value), value));
/* Return the number of bits needed, taking into account the fact
that we need one more bit for a signed than unsigned type. */
if (integer_zerop (value))
log = 0;
else if (TREE_INT_CST_HIGH (value) != 0)
log = HOST_BITS_PER_WIDE_INT + floor_log2 (TREE_INT_CST_HIGH (value));
else
log = floor_log2 (TREE_INT_CST_LOW (value));
return log + 1 + ! unsignedp;
}
/* Print an error message for invalid operands to arith operation CODE.
NOP_EXPR is used as a special case (see truthvalue_conversion). */