[Bug tree-optimization/100672] wrong code with vector shift and unary minus
rguenth at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Wed May 19 11:26:00 GMT 2021
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100672
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-05-19
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
We have in negate_expr/negate_expr_p
case RSHIFT_EXPR:
/* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
if (TREE_CODE (TREE_OPERAND (t, 1)) == INTEGER_CST)
{
tree op1 = TREE_OPERAND (t, 1);
if (wi::to_wide (op1) == TYPE_PRECISION (type) - 1)
{
tree ntype = TYPE_UNSIGNED (type)
? signed_type_for (type)
: unsigned_type_for (type);
tree temp = fold_convert_loc (loc, ntype, TREE_OPERAND (t, 0));
temp = fold_build2_loc (loc, RSHIFT_EXPR, ntype, temp, op1);
return fold_convert_loc (loc, type, temp);
}
}
note the use of TYPE_PRECISION on a vector type...
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