[Bug tree-optimization/80974] [8 Regression] wrong code (generated code hangs) at -O2 on x86_64-linux-gnu

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80974

--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> ---
The conditions and location are probably not right, but at least the testcase
passes, so this gives an idea of where the problem is.

--- tree-ssa-sccvn.c    (revision 248859)
+++ tree-ssa-sccvn.c    (working copy)
@@ -3364,20 +3364,32 @@ set_ssa_val_to (tree from, tree to)
                  if (! VN_INFO (to)->info.range_info)
                    {
                      VN_INFO (to)->info.range_info = SSA_NAME_RANGE_INFO (to);
                      VN_INFO (to)->range_info_anti_range_p
                        = SSA_NAME_ANTI_RANGE_P (to);
                    }
                  /* Rather than allocating memory and unioning the info
                     just clear it.  */
                  SSA_NAME_RANGE_INFO (to) = NULL;
                }
+
+             /* Restore old info.  */
+             if (TREE_CODE (currval) == SSA_NAME
+                 && INTEGRAL_TYPE_P (TREE_TYPE (currval))
+                 && VN_INFO (currval)->info.range_info)
+               {
+                 SSA_NAME_RANGE_INFO (currval)
+                   = VN_INFO (currval)->info.range_info;
+                 SSA_NAME_ANTI_RANGE_P (currval)
+                   = VN_INFO (currval)->range_info_anti_range_p;
+                 VN_INFO (currval)->info.range_info = NULL;
+               }
            }
          else if (POINTER_TYPE_P (TREE_TYPE (to))
                   && SSA_NAME_PTR_INFO (to))
            {
              if (SSA_NAME_IS_DEFAULT_DEF (to)
                  || dominated_by_p_w_unex
                        (gimple_bb (SSA_NAME_DEF_STMT (from)),
                         gimple_bb (SSA_NAME_DEF_STMT (to))))
                /* Keep the info from the dominator.  */
                ;