Initial commit of analyzer

This patch adds a static analysis pass to the middle-end, focusing
for this release on C code, and malloc/free issues in particular.

See:
 https://gcc.gnu.org/wiki/DavidMalcolm/StaticAnalyzer

gcc/ChangeLog:
	* Makefile.in (lang_opt_files): Add analyzer.opt.
	(ANALYZER_OBJS): New.
	(OBJS): Add digraph.o, graphviz.o, ordered-hash-map-tests.o,
	tristate.o and ANALYZER_OBJS.
	(TEXI_GCCINT_FILES): Add analyzer.texi.
	* common.opt (-fanalyzer): New driver option.
	* config.in: Regenerate.
	* configure: Regenerate.
	* configure.ac (--disable-analyzer, ENABLE_ANALYZER): New option.
	(gccdepdir): Also create depdir for "analyzer" subdir.
	* digraph.cc: New file.
	* digraph.h: New file.
	* doc/analyzer.texi: New file.
	* doc/gccint.texi ("Static Analyzer") New menu item.
	(analyzer.texi): Include it.
	* doc/invoke.texi ("Static Analyzer Options"): New list and new section.
	("Warning Options"): Add static analysis warnings to the list.
	(-Wno-analyzer-double-fclose): New option.
	(-Wno-analyzer-double-free): New option.
	(-Wno-analyzer-exposure-through-output-file): New option.
	(-Wno-analyzer-file-leak): New option.
	(-Wno-analyzer-free-of-non-heap): New option.
	(-Wno-analyzer-malloc-leak): New option.
	(-Wno-analyzer-possible-null-argument): New option.
	(-Wno-analyzer-possible-null-dereference): New option.
	(-Wno-analyzer-null-argument): New option.
	(-Wno-analyzer-null-dereference): New option.
	(-Wno-analyzer-stale-setjmp-buffer): New option.
	(-Wno-analyzer-tainted-array-index): New option.
	(-Wno-analyzer-use-after-free): New option.
	(-Wno-analyzer-use-of-pointer-in-stale-stack-frame): New option.
	(-Wno-analyzer-use-of-uninitialized-value): New option.
	(-Wanalyzer-too-complex): New option.
	(-fanalyzer-call-summaries): New warning.
	(-fanalyzer-checker=): New warning.
	(-fanalyzer-fine-grained): New warning.
	(-fno-analyzer-state-merge): New warning.
	(-fno-analyzer-state-purge): New warning.
	(-fanalyzer-transitivity): New warning.
	(-fanalyzer-verbose-edges): New warning.
	(-fanalyzer-verbose-state-changes): New warning.
	(-fanalyzer-verbosity=): New warning.
	(-fdump-analyzer): New warning.
	(-fdump-analyzer-callgraph): New warning.
	(-fdump-analyzer-exploded-graph): New warning.
	(-fdump-analyzer-exploded-nodes): New warning.
	(-fdump-analyzer-exploded-nodes-2): New warning.
	(-fdump-analyzer-exploded-nodes-3): New warning.
	(-fdump-analyzer-supergraph): New warning.
	* doc/sourcebuild.texi (dg-require-dot): New.
	(dg-check-dot): New.
	* gdbinit.in (break-on-saved-diagnostic): New command.
	* graphviz.cc: New file.
	* graphviz.h: New file.
	* ordered-hash-map-tests.cc: New file.
	* ordered-hash-map.h: New file.
	* passes.def (pass_analyzer): Add before
	pass_ipa_whole_program_visibility.
	* selftest-run-tests.c (selftest::run_tests): Call
	selftest::ordered_hash_map_tests_cc_tests.
	* selftest.h (selftest::ordered_hash_map_tests_cc_tests): New
	decl.
	* shortest-paths.h: New file.
	* timevar.def (TV_ANALYZER): New timevar.
	(TV_ANALYZER_SUPERGRAPH): Likewise.
	(TV_ANALYZER_STATE_PURGE): Likewise.
	(TV_ANALYZER_PLAN): Likewise.
	(TV_ANALYZER_SCC): Likewise.
	(TV_ANALYZER_WORKLIST): Likewise.
	(TV_ANALYZER_DUMP): Likewise.
	(TV_ANALYZER_DIAGNOSTICS): Likewise.
	(TV_ANALYZER_SHORTEST_PATHS): Likewise.
	* tree-pass.h (make_pass_analyzer): New decl.
	* tristate.cc: New file.
	* tristate.h: New file.

gcc/analyzer/ChangeLog:
	* ChangeLog: New file.
	* analyzer-selftests.cc: New file.
	* analyzer-selftests.h: New file.
	* analyzer.opt: New file.
	* analysis-plan.cc: New file.
	* analysis-plan.h: New file.
	* analyzer-logging.cc: New file.
	* analyzer-logging.h: New file.
	* analyzer-pass.cc: New file.
	* analyzer.cc: New file.
	* analyzer.h: New file.
	* call-string.cc: New file.
	* call-string.h: New file.
	* checker-path.cc: New file.
	* checker-path.h: New file.
	* constraint-manager.cc: New file.
	* constraint-manager.h: New file.
	* diagnostic-manager.cc: New file.
	* diagnostic-manager.h: New file.
	* engine.cc: New file.
	* engine.h: New file.
	* exploded-graph.h: New file.
	* pending-diagnostic.cc: New file.
	* pending-diagnostic.h: New file.
	* program-point.cc: New file.
	* program-point.h: New file.
	* program-state.cc: New file.
	* program-state.h: New file.
	* region-model.cc: New file.
	* region-model.h: New file.
	* sm-file.cc: New file.
	* sm-malloc.cc: New file.
	* sm-malloc.dot: New file.
	* sm-pattern-test.cc: New file.
	* sm-sensitive.cc: New file.
	* sm-signal.cc: New file.
	* sm-taint.cc: New file.
	* sm.cc: New file.
	* sm.h: New file.
	* state-purge.cc: New file.
	* state-purge.h: New file.
	* supergraph.cc: New file.
	* supergraph.h: New file.

gcc/testsuite/ChangeLog:
	* gcc.dg/analyzer/CVE-2005-1689-minimal.c: New test.
	* gcc.dg/analyzer/abort.c: New test.
	* gcc.dg/analyzer/alloca-leak.c: New test.
	* gcc.dg/analyzer/analyzer-decls.h: New header.
	* gcc.dg/analyzer/analyzer-verbosity-0.c: New test.
	* gcc.dg/analyzer/analyzer-verbosity-1.c: New test.
	* gcc.dg/analyzer/analyzer-verbosity-2.c: New test.
	* gcc.dg/analyzer/analyzer.exp: New suite.
	* gcc.dg/analyzer/attribute-nonnull.c: New test.
	* gcc.dg/analyzer/call-summaries-1.c: New test.
	* gcc.dg/analyzer/conditionals-2.c: New test.
	* gcc.dg/analyzer/conditionals-3.c: New test.
	* gcc.dg/analyzer/conditionals-notrans.c: New test.
	* gcc.dg/analyzer/conditionals-trans.c: New test.
	* gcc.dg/analyzer/data-model-1.c: New test.
	* gcc.dg/analyzer/data-model-2.c: New test.
	* gcc.dg/analyzer/data-model-3.c: New test.
	* gcc.dg/analyzer/data-model-4.c: New test.
	* gcc.dg/analyzer/data-model-5.c: New test.
	* gcc.dg/analyzer/data-model-5b.c: New test.
	* gcc.dg/analyzer/data-model-5c.c: New test.
	* gcc.dg/analyzer/data-model-5d.c: New test.
	* gcc.dg/analyzer/data-model-6.c: New test.
	* gcc.dg/analyzer/data-model-7.c: New test.
	* gcc.dg/analyzer/data-model-8.c: New test.
	* gcc.dg/analyzer/data-model-9.c: New test.
	* gcc.dg/analyzer/data-model-11.c: New test.
	* gcc.dg/analyzer/data-model-12.c: New test.
	* gcc.dg/analyzer/data-model-13.c: New test.
	* gcc.dg/analyzer/data-model-14.c: New test.
	* gcc.dg/analyzer/data-model-15.c: New test.
	* gcc.dg/analyzer/data-model-16.c: New test.
	* gcc.dg/analyzer/data-model-17.c: New test.
	* gcc.dg/analyzer/data-model-18.c: New test.
	* gcc.dg/analyzer/data-model-19.c: New test.
	* gcc.dg/analyzer/data-model-path-1.c: New test.
	* gcc.dg/analyzer/disabling.c: New test.
	* gcc.dg/analyzer/dot-output.c: New test.
	* gcc.dg/analyzer/double-free-lto-1-a.c: New test.
	* gcc.dg/analyzer/double-free-lto-1-b.c: New test.
	* gcc.dg/analyzer/double-free-lto-1.h: New header.
	* gcc.dg/analyzer/equivalence.c: New test.
	* gcc.dg/analyzer/explode-1.c: New test.
	* gcc.dg/analyzer/explode-2.c: New test.
	* gcc.dg/analyzer/factorial.c: New test.
	* gcc.dg/analyzer/fibonacci.c: New test.
	* gcc.dg/analyzer/fields.c: New test.
	* gcc.dg/analyzer/file-1.c: New test.
	* gcc.dg/analyzer/file-2.c: New test.
	* gcc.dg/analyzer/function-ptr-1.c: New test.
	* gcc.dg/analyzer/function-ptr-2.c: New test.
	* gcc.dg/analyzer/function-ptr-3.c: New test.
	* gcc.dg/analyzer/gzio-2.c: New test.
	* gcc.dg/analyzer/gzio-3.c: New test.
	* gcc.dg/analyzer/gzio-3a.c: New test.
	* gcc.dg/analyzer/gzio.c: New test.
	* gcc.dg/analyzer/infinite-recursion.c: New test.
	* gcc.dg/analyzer/loop-2.c: New test.
	* gcc.dg/analyzer/loop-2a.c: New test.
	* gcc.dg/analyzer/loop-3.c: New test.
	* gcc.dg/analyzer/loop-4.c: New test.
	* gcc.dg/analyzer/loop.c: New test.
	* gcc.dg/analyzer/malloc-1.c: New test.
	* gcc.dg/analyzer/malloc-2.c: New test.
	* gcc.dg/analyzer/malloc-3.c: New test.
	* gcc.dg/analyzer/malloc-callbacks.c: New test.
	* gcc.dg/analyzer/malloc-dce.c: New test.
	* gcc.dg/analyzer/malloc-dedupe-1.c: New test.
	* gcc.dg/analyzer/malloc-ipa-1.c: New test.
	* gcc.dg/analyzer/malloc-ipa-10.c: New test.
	* gcc.dg/analyzer/malloc-ipa-11.c: New test.
	* gcc.dg/analyzer/malloc-ipa-12.c: New test.
	* gcc.dg/analyzer/malloc-ipa-13.c: New test.
	* gcc.dg/analyzer/malloc-ipa-2.c: New test.
	* gcc.dg/analyzer/malloc-ipa-3.c: New test.
	* gcc.dg/analyzer/malloc-ipa-4.c: New test.
	* gcc.dg/analyzer/malloc-ipa-5.c: New test.
	* gcc.dg/analyzer/malloc-ipa-6.c: New test.
	* gcc.dg/analyzer/malloc-ipa-7.c: New test.
	* gcc.dg/analyzer/malloc-ipa-8-double-free.c: New test.
	* gcc.dg/analyzer/malloc-ipa-8-lto-a.c: New test.
	* gcc.dg/analyzer/malloc-ipa-8-lto-b.c: New test.
	* gcc.dg/analyzer/malloc-ipa-8-lto-c.c: New test.
	* gcc.dg/analyzer/malloc-ipa-8-lto.h: New test.
	* gcc.dg/analyzer/malloc-ipa-8-unchecked.c: New test.
	* gcc.dg/analyzer/malloc-ipa-9.c: New test.
	* gcc.dg/analyzer/malloc-macro-inline-events.c: New test.
	* gcc.dg/analyzer/malloc-macro-separate-events.c: New test.
	* gcc.dg/analyzer/malloc-macro.h: New header.
	* gcc.dg/analyzer/malloc-many-paths-1.c: New test.
	* gcc.dg/analyzer/malloc-many-paths-2.c: New test.
	* gcc.dg/analyzer/malloc-many-paths-3.c: New test.
	* gcc.dg/analyzer/malloc-paths-1.c: New test.
	* gcc.dg/analyzer/malloc-paths-10.c: New test.
	* gcc.dg/analyzer/malloc-paths-2.c: New test.
	* gcc.dg/analyzer/malloc-paths-3.c: New test.
	* gcc.dg/analyzer/malloc-paths-4.c: New test.
	* gcc.dg/analyzer/malloc-paths-5.c: New test.
	* gcc.dg/analyzer/malloc-paths-6.c: New test.
	* gcc.dg/analyzer/malloc-paths-7.c: New test.
	* gcc.dg/analyzer/malloc-paths-8.c: New test.
	* gcc.dg/analyzer/malloc-paths-9.c: New test.
	* gcc.dg/analyzer/malloc-vs-local-1a.c: New test.
	* gcc.dg/analyzer/malloc-vs-local-1b.c: New test.
	* gcc.dg/analyzer/malloc-vs-local-2.c: New test.
	* gcc.dg/analyzer/malloc-vs-local-3.c: New test.
	* gcc.dg/analyzer/malloc-vs-local-4.c: New test.
	* gcc.dg/analyzer/operations.c: New test.
	* gcc.dg/analyzer/params-2.c: New test.
	* gcc.dg/analyzer/params.c: New test.
	* gcc.dg/analyzer/paths-1.c: New test.
	* gcc.dg/analyzer/paths-1a.c: New test.
	* gcc.dg/analyzer/paths-2.c: New test.
	* gcc.dg/analyzer/paths-3.c: New test.
	* gcc.dg/analyzer/paths-4.c: New test.
	* gcc.dg/analyzer/paths-5.c: New test.
	* gcc.dg/analyzer/paths-6.c: New test.
	* gcc.dg/analyzer/paths-7.c: New test.
	* gcc.dg/analyzer/pattern-test-1.c: New test.
	* gcc.dg/analyzer/pattern-test-2.c: New test.
	* gcc.dg/analyzer/pointer-merging.c: New test.
	* gcc.dg/analyzer/pr61861.c: New test.
	* gcc.dg/analyzer/pragma-1.c: New test.
	* gcc.dg/analyzer/scope-1.c: New test.
	* gcc.dg/analyzer/sensitive-1.c: New test.
	* gcc.dg/analyzer/setjmp-1.c: New test.
	* gcc.dg/analyzer/setjmp-2.c: New test.
	* gcc.dg/analyzer/setjmp-3.c: New test.
	* gcc.dg/analyzer/setjmp-4.c: New test.
	* gcc.dg/analyzer/setjmp-5.c: New test.
	* gcc.dg/analyzer/setjmp-6.c: New test.
	* gcc.dg/analyzer/setjmp-7.c: New test.
	* gcc.dg/analyzer/setjmp-7a.c: New test.
	* gcc.dg/analyzer/setjmp-8.c: New test.
	* gcc.dg/analyzer/setjmp-9.c: New test.
	* gcc.dg/analyzer/signal-1.c: New test.
	* gcc.dg/analyzer/signal-2.c: New test.
	* gcc.dg/analyzer/signal-3.c: New test.
	* gcc.dg/analyzer/signal-4a.c: New test.
	* gcc.dg/analyzer/signal-4b.c: New test.
	* gcc.dg/analyzer/strcmp-1.c: New test.
	* gcc.dg/analyzer/switch.c: New test.
	* gcc.dg/analyzer/taint-1.c: New test.
	* gcc.dg/analyzer/zlib-1.c: New test.
	* gcc.dg/analyzer/zlib-2.c: New test.
	* gcc.dg/analyzer/zlib-3.c: New test.
	* gcc.dg/analyzer/zlib-4.c: New test.
	* gcc.dg/analyzer/zlib-5.c: New test.
	* gcc.dg/analyzer/zlib-6.c: New test.
	* lib/gcc-defs.exp (dg-check-dot): New procedure.
	* lib/target-supports.exp (check_dot_available): New procedure.
	(check_effective_target_analyzer): New.
	* lib/target-supports-dg.exp (dg-require-dot): New procedure.

1 files changed, 299 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/analyzer/malloc-paths-9.c b/gcc/testsuite/gcc.dg/analyzer/malloc-paths-9.c
new file mode 100644
index 0000000..7b3a0a1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/malloc-paths-9.c
@@ -0,0 +1,299 @@
+/* { dg-additional-options "-fdiagnostics-show-line-numbers -fdiagnostics-path-format=inline-events -fdiagnostics-show-caret" } */
+/* { dg-enable-nn-line-numbers "" } */
+
+#include <stdlib.h>
+
+void test_1 (void)
+{
+  void *ptr = malloc (1024);
+  free (ptr);
+  free (ptr); /* { dg-warning "double-'free' of 'ptr'"  } */
+}
+/* { dg-begin-multiline-output "" }
+   NN |   free (ptr);
+      |   ^~~~~~~~~~
+  'test_1': events 1-3
+    |
+    |   NN |   void *ptr = malloc (1024);
+    |      |               ^~~~~~~~~~~~~
+    |      |               |
+    |      |               (1) allocated here
+    |   NN |   free (ptr);
+    |      |   ~~~~~~~~~~   
+    |      |   |
+    |      |   (2) first 'free' here
+    |   NN |   free (ptr);
+    |      |   ~~~~~~~~~~   
+    |      |   |
+    |      |   (3) second 'free' here; first 'free' was at (2)
+    |
+   { dg-end-multiline-output "" } */
+
+void test_2 (int x, int y)
+{
+  void *ptr = malloc (1024);
+  if (x)
+    free (ptr);
+  if (y)
+    free (ptr); /* { dg-warning "double-'free' of 'ptr'"  } */
+} /* { dg-warning "leak of 'ptr'"  } */
+
+/* "double-'free' of 'ptr'".  */
+/* { dg-begin-multiline-output "" }
+   NN |     free (ptr);
+      |     ^~~~~~~~~~
+  'test_2': events 1-7
+    |
+    |   NN |   void *ptr = malloc (1024);
+    |      |               ^~~~~~~~~~~~~
+    |      |               |
+    |      |               (1) allocated here
+    |   NN |   if (x)
+    |      |      ~         
+    |      |      |
+    |      |      (2) following 'true' branch (when 'x != 0')...
+    |   NN |     free (ptr);
+    |      |     ~~~~~~~~~~ 
+    |      |     |
+    |      |     (3) ...to here
+    |      |     (4) first 'free' here
+    |   NN |   if (y)
+    |      |      ~         
+    |      |      |
+    |      |      (5) following 'true' branch (when 'y != 0')...
+    |   NN |     free (ptr);
+    |      |     ~~~~~~~~~~ 
+    |      |     |
+    |      |     (6) ...to here
+    |      |     (7) second 'free' here; first 'free' was at (4)
+    |
+   { dg-end-multiline-output "" } */
+
+/* "leak of 'ptr'.  */
+/* { dg-begin-multiline-output "" }
+   NN | }
+      | ^
+  'test_2': events 1-6
+    |
+    |   NN |   void *ptr = malloc (1024);
+    |      |               ^~~~~~~~~~~~~
+    |      |               |
+    |      |               (1) allocated here
+    |   NN |   if (x)
+    |      |      ~         
+    |      |      |
+    |      |      (2) following 'false' branch (when 'x == 0')...
+    |   NN |     free (ptr);
+    |   NN |   if (y)
+    |      |      ~         
+    |      |      |
+    |      |      (3) ...to here
+    |      |      (4) following 'false' branch (when 'y == 0')...
+    |   NN |     free (ptr);
+    |   NN | }
+    |      | ~              
+    |      | |
+    |      | (5) ...to here
+    |      | (6) 'ptr' leaks here; was allocated at (1)
+    |
+   { dg-end-multiline-output "" } */
+
+int test_3 (int x, int y)
+{
+  int *ptr = (int *)malloc (sizeof (int));
+  *ptr = 42; /* { dg-warning "dereference of possibly-NULL 'ptr'" } */
+  if (x)
+    free (ptr);
+
+  *ptr = 19; /* { dg-warning "use after 'free' of 'ptr'" } */
+  // TODO: two warnings here:  one is from sm-malloc, the other from region model
+
+  if (y)
+    free (ptr); /* No double-'free' warning: we've already attempted
+		   to dereference it above.  */
+  return *ptr; /* { dg-warning "use after 'free' of 'ptr'" } */
+  // TODO: two warnings here:  one is from sm-malloc, the other from region model
+  /* { dg-warning "leak of 'ptr'" "" { target *-*-* } .-2 } */
+}
+
+/* "dereference of possibly-NULL 'ptr'".  */
+/* { dg-begin-multiline-output "" }
+   NN |   *ptr = 42;
+      |   ~~~~~^~~~
+  'test_3': events 1-2
+    |
+    |   NN |   int *ptr = (int *)malloc (sizeof (int));
+    |      |                     ^~~~~~~~~~~~~~~~~~~~~
+    |      |                     |
+    |      |                     (1) this call could return NULL
+    |   NN |   *ptr = 42;
+    |      |   ~~~~~~~~~          
+    |      |        |
+    |      |        (2) 'ptr' could be NULL: unchecked value from (1)
+    |
+   { dg-end-multiline-output "" } */
+
+/* "use after 'free' of 'ptr'".  */
+/* { dg-begin-multiline-output "" }
+   NN |   *ptr = 19;
+      |   ~~~~~^~~~
+  'test_3': events 1-6
+    |
+    |   NN |   int *ptr = (int *)malloc (sizeof (int));
+    |      |                     ^~~~~~~~~~~~~~~~~~~~~
+    |      |                     |
+    |      |                     (1) allocated here
+    |   NN |   *ptr = 42;
+    |      |   ~~~~~~~~~          
+    |      |        |
+    |      |        (2) assuming 'ptr' is non-NULL
+    |   NN |   if (x)
+    |      |      ~               
+    |      |      |
+    |      |      (3) following 'true' branch (when 'x != 0')...
+    |   NN |     free (ptr);
+    |      |     ~~~~~~~~~~       
+    |      |     |
+    |      |     (4) ...to here
+    |      |     (5) freed here
+    |   NN | 
+    |   NN |   *ptr = 19;
+    |      |   ~~~~~~~~~          
+    |      |        |
+    |      |        (6) use after 'free' of 'ptr'; freed at (5)
+    |
+   { dg-end-multiline-output "" } */
+
+/* "use after 'free' of 'ptr'".  */
+/* { dg-begin-multiline-output "" }
+   NN |   return *ptr;
+      |          ^~~~
+  'test_3': events 1-8
+    |
+    |   NN |   int *ptr = (int *)malloc (sizeof (int));
+    |      |                     ^~~~~~~~~~~~~~~~~~~~~
+    |      |                     |
+    |      |                     (1) allocated here
+    |   NN |   *ptr = 42;
+    |      |   ~~~~~~~~~          
+    |      |        |
+    |      |        (2) assuming 'ptr' is non-NULL
+    |   NN |   if (x)
+    |      |      ~               
+    |      |      |
+    |      |      (3) following 'false' branch (when 'x == 0')...
+    |......
+    |   NN |   *ptr = 19;
+    |      |   ~~~~~~~~~          
+    |      |        |
+    |      |        (4) ...to here
+    |......
+    |   NN |   if (y)
+    |      |      ~               
+    |      |      |
+    |      |      (5) following 'true' branch (when 'y != 0')...
+    |   NN |     free (ptr);
+    |      |     ~~~~~~~~~~       
+    |      |     |
+    |      |     (6) ...to here
+    |      |     (7) freed here
+    |   NN |      
+    |   NN |   return *ptr;
+    |      |          ~~~~        
+    |      |          |
+    |      |          (8) use after 'free' of 'ptr'; freed at (7)
+    |
+   { dg-end-multiline-output "" } */
+
+/* "leak of 'ptr'".  */
+/* { dg-begin-multiline-output "" }
+   NN |   return *ptr;
+      |          ^~~~
+  'test_3': events 1-7
+    |
+    |   NN |   int *ptr = (int *)malloc (sizeof (int));
+    |      |                     ^~~~~~~~~~~~~~~~~~~~~
+    |      |                     |
+    |      |                     (1) allocated here
+    |   NN |   *ptr = 42;
+    |      |   ~~~~~~~~~          
+    |      |        |
+    |      |        (2) assuming 'ptr' is non-NULL
+    |   NN |   if (x)
+    |      |      ~               
+    |      |      |
+    |      |      (3) following 'false' branch (when 'x == 0')...
+    |......
+    |   NN |   *ptr = 19;
+    |      |   ~~~~~~~~~          
+    |      |        |
+    |      |        (4) ...to here
+    |......
+    |   NN |   if (y)
+    |      |      ~               
+    |      |      |
+    |      |      (5) following 'false' branch (when 'y == 0')...
+    |......
+    |   NN |   return *ptr;
+    |      |          ~~~~        
+    |      |          |
+    |      |          (6) ...to here
+    |      |          (7) 'ptr' leaks here; was allocated at (1)
+    |
+   { dg-end-multiline-output "" } */
+
+/* "use after 'free' of 'ptr'".  */
+/* { dg-begin-multiline-output "" }
+   NN |   *ptr = 19;
+      |   ~~~~~^~~~
+  'test_3': events 1-3
+    |
+    |   NN |   if (x)
+    |      |      ^
+    |      |      |
+    |      |      (1) following 'true' branch (when 'x != 0')...
+    |   NN |     free (ptr);
+    |      |     ~~~~~~~~~~
+    |      |     |
+    |      |     (2) ...to here
+    |   NN | 
+    |   NN |   *ptr = 19;
+    |      |   ~~~~~~~~~
+    |      |        |
+    |      |        (3) use after 'free' of 'ptr' here
+    |
+   { dg-end-multiline-output "" } */
+
+/* "use after 'free' of 'ptr'".  */
+/* { dg-begin-multiline-output "" }
+   NN |   return *ptr;
+      |          ^~~~
+  'test_3': events 1-5
+    |
+    |   NN |   if (x)
+    |      |      ^
+    |      |      |
+    |      |      (1) following 'false' branch (when 'x == 0')...
+    |......
+    |   NN |   *ptr = 19;
+    |      |   ~~~~~~~~~
+    |      |        |
+    |      |        (2) ...to here
+    |......
+    |   NN |   if (y)
+    |      |      ~
+    |      |      |
+    |      |      (3) following 'true' branch (when 'y != 0')...
+    |   NN |     free (ptr);
+    |      |     ~~~~~~~~~~
+    |      |     |
+    |      |     (4) ...to here
+    |   NN |      to dereference it above
+    |   NN |   return *ptr;
+    |      |          ~~~~
+    |      |          |
+    |      |          (5) use after 'free' of 'ptr' here
+    |
+   { dg-end-multiline-output "" } */
+/* TODO: this is really a duplicate; can we either eliminate it, or
+   improve the path?  */