[PATCH] Ignore shifts larger than precision in operator_rshift::op1_range.
Aldy Hernandez
aldyh@redhat.com
Mon Oct 12 09:51:17 GMT 2020
Pushed as obvious.
gcc/ChangeLog:
PR tree-optimization/97371
* range-op.cc (operator_rshift::op1_range): Ignore shifts larger than
or equal to type precision.
gcc/testsuite/ChangeLog:
* gcc.dg/pr97371.c: New test.
---
gcc/range-op.cc | 7 +++++++
gcc/testsuite/gcc.dg/pr97371.c | 8 ++++++++
2 files changed, 15 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr97371.c
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index d1a11b34894..ce6ae2de20c 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -1626,6 +1626,13 @@ operator_rshift::op1_range (irange &r,
tree shift;
if (op2.singleton_p (&shift))
{
+ // Ignore nonsensical shifts.
+ unsigned prec = TYPE_PRECISION (type);
+ if (wi::ge_p (wi::to_wide (shift),
+ wi::uhwi (prec, TYPE_PRECISION (TREE_TYPE (shift))),
+ UNSIGNED))
+ return false;
+
// Folding the original operation may discard some impossible
// ranges from the LHS.
int_range_max lhs_refined;
diff --git a/gcc/testsuite/gcc.dg/pr97371.c b/gcc/testsuite/gcc.dg/pr97371.c
new file mode 100644
index 00000000000..ffefad0287e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97371.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -w" } */
+
+int a, b;
+void c() {
+ if (b >> 38)
+ a = b;
+}
--
2.26.2
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