https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88301
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Keywords| |missed-optimization
Last reconfirmed| |2018-12-03
Component|middle-end |tree-optimization
CC| |rguenth at gcc dot gnu.org
Ever confirmed|0 |1
Summary|Optimization regression |[8/9 Regression]
|with undefined unsigned |Optimization regression
|overflow |with undefined unsigned
| |overflow
Target Milestone|--- |8.3
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
This would be
void
evrp_range_analyzer::record_ranges_from_incoming_edge (basic_block bb)
{
...
if (is_fallthru
&& all_uses_feed_or_dominated_by_stmt (vrs[i].first, stmt))
{
set_ssa_range_info (vrs[i].first, vrs[i].second);
maybe_set_nonzero_bits (pred_e, vrs[i].first);
}
looks like we do not manage to find a new range for the assert for _2.
Hmm, for _2 we get
_2 <= 4294967294
that's of course not too useful. Looks like we are not factoring in
SSA range info when we register asserts for _3 != 0. It's of course
somewhat of a special case...
The code we currently add the assert from is
/* Add asserts for NAME cmp CST and NAME being defined as
NAME = NAME2 & CST2.
Extract CST2 from the and.
Also handle
NAME = (unsigned) NAME2;
casts where NAME's type is unsigned and has smaller precision
than NAME2's type as if it was NAME = NAME2 & MASK. */
names[0] = NULL_TREE;
names[1] = NULL_TREE;
cst2 = NULL_TREE;
if (rhs_code == BIT_AND_EXPR
what we'd like to add is a case where we can look through a non-value-changing
conversion identifying that using SSA range-info. Like
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c (revision 266733)
+++ gcc/tree-vrp.c (working copy)
@@ -2966,6 +2966,20 @@ register_edge_assert_for_2 (tree name, e
add_assert_info (asserts, name2, tmp, new_comp_code, new_val);
}
+ wide_int rmin, rmax;
+ tree rhs1 = gimple_assign_rhs1 (def_stmt);
+ if (CONVERT_EXPR_CODE_P (rhs_code)
+ && INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+ && int_fits_type_p (val, TREE_TYPE (rhs1))
+ && (TYPE_PRECISION (TREE_TYPE (name)) > TYPE_PRECISION (TREE_TYPE
(rhs1))
+ || (get_range_info (rhs1, &rmin, &rmax) == VR_RANGE
+ && (wi::min_precision (rmin, TYPE_SIGN (TREE_TYPE (rhs1)))
+ <= TYPE_PRECISION (TREE_TYPE (name)))
+ && (wi::min_precision (rmax, TYPE_SIGN (TREE_TYPE (rhs1)))
+ <= TYPE_PRECISION (TREE_TYPE (name))))))
+ add_assert_info (asserts, rhs1, rhs1,
+ comp_code, fold_convert (TREE_TYPE (rhs1), val));
+
/* Add asserts for NAME cmp CST and NAME being defined as
NAME = NAME2 & CST2.
but struggling with the range-fits-type idiom (we must have several copies
of that now...). Maybe it should be instead
&& wi::le_p (wi::to_widest (wi::min_value (TYPE_PRECISION
(TREE_TYPE (name)),
TYPE_SIGN
(name))),
wi::to_widest (rmin), SIGNED)
&& wi::ge_p (wi::to_widest (wi::max_value (TYPE_PRECISION
(TREE_TYPE (name)),
TYPE_SIGN
(name))),
wi::to_widest (rmax), SIGNED)
