The following uses context sensitive ranger for determining whether
the input to the table based CTZ is ever zero.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
* tree-ssa-forwprop.cc (simplify_count_trailing_zeroes):
Use ranger instead of tree_expr_nonzero_p.
---
gcc/tree-ssa-forwprop.cc | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index 4ef75ba98bd..a60862a4b1a 100644
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -2667,7 +2667,12 @@ simplify_count_trailing_zeroes (gimple_stmt_iterator
*gsi)
int nargs = 2;
/* If the input value can't be zero, don't special case ctz (0). */
- if (tree_expr_nonzero_p (res_ops[0]))
+ range_query *q = get_range_query (cfun);
+ if (q == get_global_range_query ())
+ q = enable_ranger (cfun);
+ int_range_max vr;
+ if (q->range_of_expr (vr, res_ops[0], stmt)
+ && !range_includes_zero_p (vr))
{
zero_ok = true;
zero_val = 0;
--
2.43.0
