As discussed in the PR, this fixes the range-ops cast code to handle
casts where the precision of the RHS is only 1 greater than the precision
of the LHS.
This is actually Andrew's patch.
Tested on x86-64 Linux.
Pushed.
gcc/ChangeLog:
PR tree-optimization/97317
* range-op.cc (operator_cast::op1_range):
gcc/testsuite/ChangeLog:
* gcc.dg/pr97317.c: New test.
---
gcc/range-op.cc | 25 ++++++++++++++++++-------
gcc/testsuite/gcc.dg/pr97317.c | 11 +++++++++++
2 files changed, 29 insertions(+), 7 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr97317.c
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 22bc23c1bbf..d1a11b34894 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -1849,14 +1849,25 @@ operator_cast::op1_range (irange &r, tree type,
type,
converted_lhs,
lim_range);
- // And union this with the entire outer types negative range.
- int_range_max neg (type,
- wi::min_value (TYPE_PRECISION (type),
- SIGNED),
- lim - 1);
- neg.union_ (lhs_neg);
+ // lhs_neg now has all the negative versions of the LHS.
+ // Now union in all the values from SIGNED MIN (0x80000) to
+ // lim-1 in order to fill in all the ranges with the upper
+ // bits set.
+
+ // PR 97317. If the lhs has only 1 bit less precision than the rhs,
+ // we don't need to create a range from min to lim-1
+ // calculate neg range traps trying to create [lim, lim - 1].
+ wide_int min_val = wi::min_value (TYPE_PRECISION (type), SIGNED);
+ if (lim != min_val)
+ {
+ int_range_max neg (type,
+ wi::min_value (TYPE_PRECISION (type),
+ SIGNED),
+ lim - 1);
+ lhs_neg.union_ (neg);
+ }
// And finally, munge the signed and unsigned portions.
- r.union_ (neg);
+ r.union_ (lhs_neg);
}
// And intersect with any known value passed in the extra operand.
r.intersect (op2);
diff --git a/gcc/testsuite/gcc.dg/pr97317.c b/gcc/testsuite/gcc.dg/pr97317.c
new file mode 100644
index 00000000000..f07327ac9a2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97317.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+struct a {
+ unsigned c : 17;
+};
+struct a b;
+int d(void) {
+ short e = b.c;
+ return e ? 0 : b.c;
+}
--
2.26.2
