https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106630
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
We are folding a POINTER_PLUS_EXPR of
(vector(8) short int *) &g + a_9 * 48
and
48
which first gets to (vector(8) short int *) &g + (a_9 * 48 + 48)
which gets
/* (A * C) +- (B * C) -> (A+-B) * C and (A * C) +- A -> A * (C+-1).
Modeled after fold_plusminus_mult_expr. */
applied producing (a_9 + 1) * 48
the fold code produces a (sizetype) cast around (unsigned long) which is
useless (but not in GENERIC) and then
/* Narrow integer multiplication by a zero_one_valued_p operand.
Multiplication by [0,1] is guaranteed not to overflow. */
(simplify
(convert (mult@0 zero_one_valued_p@1 INTEGER_CST@2))
(if (INTEGRAL_TYPE_P (type)
&& INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@0)))
(mult (convert @1) (convert @2))))
triggers but folding this multiplication via fold-const.cc extract_muldiv
hoists the conversion again:
if (TREE_CODE (arg1) == INTEGER_CST
&& (tem = extract_muldiv (op0, arg1, code, NULL_TREE,
&strict_overflow_p)) != 0)
{
if (strict_overflow_p)
fold_overflow_warning (("assuming signed overflow does not "
"occur when simplifying "
"multiplication"),
WARN_STRICT_OVERFLOW_MISC);
return fold_convert_loc (loc, type, tem);
which triggers the endless loop. The fix might be to change the above
pattern guard to TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (@0))
which would match what the comment says.
The comment about DOM + missing cprop remains of course.
I'm testing the above.
