David Miller <da...@davemloft.net> writes:
> On sparc a simple test like (from the PR tree-optimization/53410 testcase):
>
> ====================
> typedef int V __attribute__((vector_size (4 * sizeof (int))));
> typedef unsigned int W __attribute__((vector_size (4 * sizeof (int))));
>
> void
> f10 (W *p, W *q)
> {
> *p = *p < (((const W) { 1U, 1U, 1U, 1U }) << *q);
> }
> ====================
>
> aborts in convert_move() because we're trying to move a TImode value
> into a V2SImode one. How does that happen?
>
> On sparc the generic tree vector layer turns the above expression into
> two V2SImode shifts. The *q parts of each shift are represented as:
>
> (subreg:V2SI (reg:TI xxx) 0)
> (subreg:V2SI (reg:TI xxx) 8)
>
> When we get down into expand_shift_1(), that SUBREG is stripped out by
> the SHIFT_COUNT_TRUNCATED code, and that's how we end up in the crash
> by the time we reach convert_move() (via expand_binop() -->
> expand_binop_directly() --> convert_modes() --> convert_move()).
>
> Perhaps we should elide the SUBREG stripping if the subreg has a
> vector mode?
Agreed, although...
> Actually, what seems to confuse this code is that we're passing
> TImode values around for this vector that the target doesn't have
> direct support for. The SUBREG stripper explicitly checks for
> INTEGRAL_MODE_P, and indeed TImode is integral.
...given that the code is like you say written:
if (SHIFT_COUNT_TRUNCATED)
{
if (CONST_INT_P (op1)
...
else if (GET_CODE (op1) == SUBREG
&& subreg_lowpart_p (op1)
&& INTEGRAL_MODE_P (GET_MODE (SUBREG_REG (op1))))
op1 = SUBREG_REG (op1);
}
INTEGRAL_MODE_P (GET_MODE (op1)) might be better than an explicit
VECTOR_MODE_P check. The code really doesn't make sense for anything
other than integers.
(It amounts to the same thing in practice, of course...)
Richard
