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(expand_expr, ARRAY_REF): Coerce low_bound to sizetype. 

From-SVN: r5313
This commit is contained in:
Per Bothner 1993-09-12 23:01:37 -07:00
parent 59b22f6465
commit d4c8913966
1 changed files with 13 additions and 2 deletions
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15
gcc/expr.c
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@ -3889,9 +3889,20 @@ expand_expr (exp, target, tmode, modifier)
tree index_type = TREE_TYPE (index);
int i;
/* Optimize the special-case of a zero lower bound. */
/* Optimize the special-case of a zero lower bound.
We convert the low_bound to sizetype to avoid some problems
with constant folding. (E.g. suppose the lower bound is 1,
and its mode is QI. Without the conversion, (ARRAY
+(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
+INDEX), which becomes (ARRAY+255+INDEX). Oops!)
But sizetype isn't quite right either (especially if
the lowbound is negative). FIXME */
if (! integer_zerop (low_bound))
index = fold (build (MINUS_EXPR, index_type, index, low_bound));
index = fold (build (MINUS_EXPR, index_type, index,
convert (sizetype, low_bound)));
if (TREE_CODE (index) != INTEGER_CST
|| TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)