[PUSHED] testsuite: Add a returns_twice testcase for PR126815 [PR126815]

[Andrea Pinski]

This adds a returns_twice testcase that shows the ICE (already fixed)
and show that adding a stmt before the call does not work either.

Pushed as obvious after a quick test on x86_64-linux-gnu to make sure it passes.

        PR tree-optimization/126815

gcc/testsuite/ChangeLog:

        * gcc.dg/torture/returns-twice-1.c: New test.

Signed-off-by: Andrea Pinski <andrew.pin...@oss.qualcomm.com>
---
 .../gcc.dg/torture/returns-twice-1.c          | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/torture/returns-twice-1.c

diff --git a/gcc/testsuite/gcc.dg/torture/returns-twice-1.c 
b/gcc/testsuite/gcc.dg/torture/returns-twice-1.c
new file mode 100644
index 00000000000..fbd9faa0bce
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/returns-twice-1.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* PR tree-optimization/126815 */
+int f (int) __attribute__((returns_twice));
+void sink1 (int) __attribute__((leaf));
+void sink (int);
+
+void h (int a, int b, int c)
+{
+  int t;
+  if (c){
+    sink (1);
+    t = f (a);
+  }
+  else
+    t = b;
+  if (t == 42)
+    __builtin_unreachable ();
+  sink1 (a);
+}
-- 
2.43.0