[PATCH] Fix PR91267

[Richard Biener]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2019-07-29  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/91267
        * vr-values.c (vr_values::update_value_range): Add early return
        for effectively VARYING lattice entry.

        * gcc.dg/torture/pr91267.c: New testcase.

Index: gcc/vr-values.c
===================================================================
--- gcc/vr-values.c     (revision 273792)
+++ gcc/vr-values.c     (working copy)
@@ -202,8 +202,12 @@ vr_values::update_value_range (const_tre
        new_vr->intersect (&nr);
     }
 
-  /* Update the value range, if necessary.  */
+  /* Update the value range, if necessary.  If we cannot allocate a lattice
+     entry for VAR keep it at VARYING.  This happens when DOM feeds us stmts
+     with SSA names allocated after setting up the lattice.  */
   old_vr = get_lattice_entry (var);
+  if (!old_vr)
+    return false;
   is_new = !old_vr->equal_p (*new_vr, /*ignore_equivs=*/false);
 
   if (is_new)
Index: gcc/testsuite/gcc.dg/torture/pr91267.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr91267.c      (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr91267.c      (working copy)
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+
+void bar (void);
+void baz (int);
+char *qux (void);
+int a, b;
+
+void
+foo (int f, char *d)
+{
+  char *e;
+  while (d)
+    {
+      if (f)
+       if (e)
+         bar ();
+      baz (e - (d + a));
+      b = e - d;
+      d = qux ();
+    }
+}