[pushed] analyzer: fix ICE seen with -fsanitize=undefined [PR114899]

[David Malcolm]

Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Pushed to trunk as r15-526-g1779e22150b917.

gcc/analyzer/ChangeLog:
        PR analyzer/114899
        * access-diagram.cc
        (written_svalue_spatial_item::get_label_string): Bulletproof
        against SSA_NAME_VAR being null.

gcc/testsuite/ChangeLog:
        PR analyzer/114899
        * c-c++-common/analyzer/out-of-bounds-diagram-pr114899.c: New test.

Signed-off-by: David Malcolm <dmalc...@redhat.com>
---
 gcc/analyzer/access-diagram.cc                    |  3 ++-
 .../analyzer/out-of-bounds-diagram-pr114899.c     | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 
gcc/testsuite/c-c++-common/analyzer/out-of-bounds-diagram-pr114899.c

diff --git a/gcc/analyzer/access-diagram.cc b/gcc/analyzer/access-diagram.cc
index 500480b68328..8d7461fe381d 100644
--- a/gcc/analyzer/access-diagram.cc
+++ b/gcc/analyzer/access-diagram.cc
@@ -1632,7 +1632,8 @@ protected:
     if (rep_tree)
       {
        if (TREE_CODE (rep_tree) == SSA_NAME)
-         rep_tree = SSA_NAME_VAR (rep_tree);
+         if (tree var = SSA_NAME_VAR (rep_tree))
+           rep_tree = var;
        switch (TREE_CODE (rep_tree))
          {
          default:
diff --git 
a/gcc/testsuite/c-c++-common/analyzer/out-of-bounds-diagram-pr114899.c 
b/gcc/testsuite/c-c++-common/analyzer/out-of-bounds-diagram-pr114899.c
new file mode 100644
index 000000000000..14ba540d4ec2
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/analyzer/out-of-bounds-diagram-pr114899.c
@@ -0,0 +1,15 @@
+/* Verify we don't ICE generating out-of-bounds diagram.  */
+
+/* { dg-additional-options " -fsanitize=undefined 
-fdiagnostics-text-art-charset=unicode" } */
+
+int * a() {
+  int *b = (int *)__builtin_malloc(sizeof(int));
+  int *c = b - 1;
+  ++*c;
+  return b;
+}
+
+/* We don't care about the exact diagram, just that we don't ICE.  */
+
+/* { dg-allow-blank-lines-in-output 1 } */
+/* { dg-prune-output ".*" } */
-- 
2.26.3