[gcc r15-2240] [PR rtl-optimization/115877][6/n] Add testcase from pr115877

[Jeff Law via Gcc-cvs]

https://gcc.gnu.org/g:f9a60d575f02822852aa22513c636be38f9c63ea

commit r15-2240-gf9a60d575f02822852aa22513c636be38f9c63ea
Author: Jeff Law <j...@ventanamicro.com>
Date:   Tue Jul 23 19:11:04 2024 -0600

    [PR rtl-optimization/115877][6/n] Add testcase from pr115877
    
    This just adds the testcase from pr115877.  It's working now on the trunk.  
I'm
    not done with cleanups/bugfixing, but there's no reason to not have the
    testcase installed at this point.
    
            PR rtl-optimization/115877
    gcc/testsuite
            * gcc.dg/torture/pr115877.c: New test.

Diff:
---
 gcc/testsuite/gcc.dg/torture/pr115877.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/gcc/testsuite/gcc.dg/torture/pr115877.c 
b/gcc/testsuite/gcc.dg/torture/pr115877.c
new file mode 100644
index 000000000000..432b1280b177
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr115877.c
@@ -0,0 +1,20 @@
+/* { dg-do run { target int128 } } */
+
+char a[16];
+unsigned short u;
+
+__int128
+foo (int i)
+{
+  i -= (unsigned short) ~u;
+  a[(unsigned short) i] = 1;
+  return i;
+}
+
+int
+main ()
+{
+  __int128 x = foo (0);
+  if (x != -0xffff)
+    __builtin_abort();
+}