analyzer: fix ICE when combining taint states has_ub and has_lb

gcc/analyzer/ChangeLog:
	* sm-taint.cc (taint_state_machine::combine_states): Handle combination
	of has_ub and has_lb.

gcc/testsuite/ChangeLog:
	* gcc.dg/analyzer/taint-merger.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

2 files changed, 66 insertions, 5 deletions

diff --git a/gcc/analyzer/sm-taint.cc b/gcc/analyzer/sm-taint.cc
index 3a46256b..3574565 100644
--- a/gcc/analyzer/sm-taint.cc
+++ b/gcc/analyzer/sm-taint.cc
@@ -860,15 +860,19 @@ taint_state_machine::combine_states (state_t s0, state_t s1) const
     return s0;
   if (s0 == m_tainted || s1 == m_tainted)
     return m_tainted;
-  if (s0 == m_stop)
-    return s1;
-  if (s1 == m_stop)
-    return s0;
   if (s0 == m_start)
     return s1;
   if (s1 == m_start)
     return s0;
-  gcc_unreachable ();
+  if (s0 == m_stop)
+    return s1;
+  if (s1 == m_stop)
+    return s0;
+  /* The only remaining combinations are one of has_ub and has_lb
+     (in either order).  */
+  gcc_assert ((s0 == m_has_lb && s1 == m_has_ub)
+	      || (s0 == m_has_ub && s1 == m_has_lb));
+  return m_tainted;
 }
 
 /* Check for calls to external functions marked with
diff --git a/gcc/testsuite/gcc.dg/analyzer/taint-merger.c b/gcc/testsuite/gcc.dg/analyzer/taint-merger.c
new file mode 100644
index 0000000..e4e48f3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/taint-merger.c
@@ -0,0 +1,57 @@
+/* { dg-additional-options "-fanalyzer-checker=taint" } */
+// TODO: remove need for this option
+
+#include "analyzer-decls.h"
+
+int v_start;
+
+__attribute__((tainted_args))
+void test (int v_tainted, int v_has_lb, int v_has_ub, int v_stop)
+{
+  /* Get each var into the 5 different taintedness states.  */
+  if (v_has_lb < 10)
+    return;
+  if (v_has_ub > 100)
+    return;
+  if (v_stop < 0 || v_stop > 100)
+    return;
+
+  /* Verify that we have the taintedness states we expect.  */
+
+  __analyzer_dump_state ("taint", v_start); /* { dg-warning "state: 'start'" } */
+  __analyzer_dump_state ("taint", v_tainted); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_has_lb); /* { dg-warning "state: 'has_lb'" } */
+  __analyzer_dump_state ("taint", v_has_ub); /* { dg-warning "state: 'has_ub'" } */
+  __analyzer_dump_state ("taint", v_stop); /* { dg-warning "state: 'stop'" } */
+
+  /* Check all combinations of taintedness state.  */
+  __analyzer_dump_state ("taint", v_start + v_start); /* { dg-warning "state: 'start'" } */
+  __analyzer_dump_state ("taint", v_start + v_tainted); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_start + v_has_lb); /* { dg-warning "state: 'has_lb'" } */
+  __analyzer_dump_state ("taint", v_start + v_has_ub); /* { dg-warning "state: 'has_ub'" } */
+  __analyzer_dump_state ("taint", v_start + v_stop); /* { dg-warning "state: 'stop'" } */
+
+  __analyzer_dump_state ("taint", v_tainted + v_start); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_tainted + v_tainted); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_tainted + v_has_lb); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_tainted + v_has_ub); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_tainted + v_stop); /* { dg-warning "state: 'tainted'" } */
+
+  __analyzer_dump_state ("taint", v_has_lb + v_start); /* { dg-warning "state: 'has_lb'" } */
+  __analyzer_dump_state ("taint", v_has_lb + v_tainted); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_has_lb + v_has_lb); /* { dg-warning "state: 'has_lb'" } */
+  __analyzer_dump_state ("taint", v_has_lb + v_has_ub); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_has_lb + v_stop); /* { dg-warning "state: 'has_lb'" } */
+
+  __analyzer_dump_state ("taint", v_has_ub + v_start); /* { dg-warning "state: 'has_ub'" } */
+  __analyzer_dump_state ("taint", v_has_ub + v_tainted); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_has_ub + v_has_lb); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_has_ub + v_has_ub); /* { dg-warning "state: 'has_ub'" } */
+  __analyzer_dump_state ("taint", v_has_ub + v_stop); /* { dg-warning "state: 'has_ub'" } */
+
+  __analyzer_dump_state ("taint", v_stop + v_start); /* { dg-warning "state: 'stop'" } */
+  __analyzer_dump_state ("taint", v_stop + v_tainted); /* { dg-warning "state: 'tainted'" } */
+  __analyzer_dump_state ("taint", v_stop + v_has_lb); /* { dg-warning "state: 'has_lb'" } */
+  __analyzer_dump_state ("taint", v_stop + v_has_ub); /* { dg-warning "state: 'has_ub'" } */
+  __analyzer_dump_state ("taint", v_stop + v_stop); /* { dg-warning "state: 'stop'" } */
+}