[PATCH] Expensive selftests: torture testing for fix-it boundary conditions (PR c/82050)

[David Malcolm <dmalcolm@redhat.com>]

This patch adds selftest coverage for the fix for PR c/82050 (r255214).

The selftest iterates over various "interesting" column and line-width
values to try to shake out bugs in the fix-it printing routines, a kind
of "torture" selftest.

Unfortunately this selftest is noticably slower than the other selftests;
adding it to diagnostic-show-locus.c led to:
  -fself-test: 40218 pass(es) in 0.172000 seconds
slowing down to:
  -fself-test: 97315 pass(es) in 6.109000 seconds
for an unoptimized build (e.g. when hacking with --disable-bootstrap).

Given that this affects the compile-edit-test cycle of the "gcc"
subdirectory, this felt like an unacceptable amount of overhead to add.

I attempted to optimize the test by reducing the amount of coverage, but
the test seems useful, and there seems to be a valid role for "torture"
selftests.

Hence this patch adds a:
  gcc.dg/plugin/expensive_selftests_plugin.c
with the responsibility for running "expensive" selftests, and adds the
expensive test there.  The patch moves a small amount of code from
selftest::run_tests into a helper class so that the plugin can print
a useful summary line (to reassure us that the tests are actually being
run).

With that, the compile-edit-test cycle of the "gcc" subdir is unaffected;
the plugin takes:
  expensive_selftests_plugin: 26641 pass(es) in 3.127000 seconds
which seems reasonable within the much longer time taken by "make check"
(I optimized some of the overhead away, hence the reduction from 6 seconds
above down to 3 seconds).

Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu.

OK for trunk?

gcc/ChangeLog:
	PR c/82050
	* selftest-run-tests.c (selftest::run_tests): Move start/finish code
	to...
	* selftest.c (selftest::test_runner::test_runner): New ctor.
	(selftest::test_runner::~test_runner): New dtor.
	* selftest.h (class selftest::test_runner): New class.

gcc/testsuite/ChangeLog:
	PR c/82050
	* gcc.dg/plugin/expensive-selftests-1.c: New file.
	* gcc.dg/plugin/expensive_selftests_plugin.c: New file.
	* gcc.dg/plugin/plugin.exp (plugin_test_list): Add the above.
---
 gcc/selftest-run-tests.c                           |  11 +-
 gcc/selftest.c                                     |  22 +++
 gcc/selftest.h                                     |  14 ++
 .../gcc.dg/plugin/expensive-selftests-1.c          |   3 +
 .../gcc.dg/plugin/expensive_selftests_plugin.c     | 175 +++++++++++++++++++++
 gcc/testsuite/gcc.dg/plugin/plugin.exp             |   2 +
 6 files changed, 218 insertions(+), 9 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/plugin/expensive-selftests-1.c
 create mode 100644 gcc/testsuite/gcc.dg/plugin/expensive_selftests_plugin.c

diff --git a/gcc/selftest-run-tests.c b/gcc/selftest-run-tests.c
index 6030d3b..f539c66 100644
--- a/gcc/selftest-run-tests.c
+++ b/gcc/selftest-run-tests.c
@@ -46,7 +46,7 @@ selftest::run_tests ()
      option-handling.  */
   path_to_selftest_files = flag_self_test;
 
-  long start_time = get_run_time ();
+  test_runner r ("-fself-test");
 
   /* Run all the tests, in hand-coded order of (approximate) dependencies:
      run the tests for lowest-level code first.  */
@@ -106,14 +106,7 @@ selftest::run_tests ()
      failed to be finalized can be detected by valgrind.  */
   forcibly_ggc_collect ();
 
-  /* Finished running tests.  */
-  long finish_time = get_run_time ();
-  long elapsed_time = finish_time - start_time;
-
-  fprintf (stderr,
-	   "-fself-test: %i pass(es) in %ld.%06ld seconds\n",
-	   num_passes,
-	   elapsed_time / 1000000, elapsed_time % 1000000);
+  /* Finished running tests; the test_runner dtor will print a summary.  */
 }
 
 #endif /* #if CHECKING_P */
diff --git a/gcc/selftest.c b/gcc/selftest.c
index b41b9f5..ca84bfa 100644
--- a/gcc/selftest.c
+++ b/gcc/selftest.c
@@ -213,6 +213,28 @@ locate_file (const char *name)
   return concat (path_to_selftest_files, "/", name, NULL);
 }
 
+/* selftest::test_runner's ctor.  */
+
+test_runner::test_runner (const char *name)
+: m_name (name),
+  m_start_time (get_run_time ())
+{
+}
+
+/* selftest::test_runner's dtor.  Print a summary line to stderr.  */
+
+test_runner::~test_runner ()
+{
+  /* Finished running tests.  */
+  long finish_time = get_run_time ();
+  long elapsed_time = finish_time - m_start_time;
+
+  fprintf (stderr,
+	   "%s: %i pass(es) in %ld.%06ld seconds\n",
+	   m_name, num_passes,
+	   elapsed_time / 1000000, elapsed_time % 1000000);
+}
+
 /* Selftests for libiberty.  */
 
 /* Verify that xstrndup generates EXPECTED when called on SRC and N.  */
diff --git a/gcc/selftest.h b/gcc/selftest.h
index cdad939..f282055 100644
--- a/gcc/selftest.h
+++ b/gcc/selftest.h
@@ -168,6 +168,20 @@ extern char *locate_file (const char *path);
 
 extern const char *path_to_selftest_files;
 
+/* selftest::test_runner is an implementation detail of selftest::run_tests,
+   exposed here to allow plugins to run their own suites of tests.  */
+
+class test_runner
+{
+ public:
+  test_runner (const char *name);
+  ~test_runner ();
+
+ private:
+  const char *m_name;
+  long m_start_time;
+};
+
 /* Declarations for specific families of tests (by source file), in
    alphabetical order.  */
 extern void bitmap_c_tests ();
diff --git a/gcc/testsuite/gcc.dg/plugin/expensive-selftests-1.c b/gcc/testsuite/gcc.dg/plugin/expensive-selftests-1.c
new file mode 100644
index 0000000..e464117
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/expensive-selftests-1.c
@@ -0,0 +1,3 @@
+int not_empty;
+
+/* { dg-regexp "expensive_selftests_plugin: .* pass\\(es\\) in .* seconds" } */
diff --git a/gcc/testsuite/gcc.dg/plugin/expensive_selftests_plugin.c b/gcc/testsuite/gcc.dg/plugin/expensive_selftests_plugin.c
new file mode 100644
index 0000000..9470764
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/expensive_selftests_plugin.c
@@ -0,0 +1,175 @@
+/* Run expensive selftests.  */
+/* { dg-options "-O" } */
+
+#include "gcc-plugin.h"
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "diagnostic.h"
+#include "edit-context.h"
+#include "selftest.h"
+#include "selftest-diagnostic.h"
+
+int plugin_is_GPL_compatible;
+
+#if CHECKING_P
+
+namespace selftest {
+
+/* Subroutine of test_fixit_on_very_long_line.
+   Verify that LOC has the EXPECTED_COLUMN, apart from the various
+   cases where it can't.  */
+
+static void
+verify_column (location_t loc,
+	       const line_map_ordinary *ord_map,
+	       int line_width,
+	       int expected_column)
+{
+  ASSERT_TRUE (/* Normal case.  */
+	       LOCATION_COLUMN (loc) == expected_column
+	       /* ord_map can't store columns e.g. due to
+		  max_column_hint being too high.  */
+	       || ord_map->m_column_and_range_bits == 0
+	       /* Running out of location_t values.  */
+	       || loc > LINE_MAP_MAX_LOCATION_WITH_COLS
+	       /* column exceeds LINE_MAP_MAX_COLUMN_NUMBER.  */
+	       || expected_column > (int)LINE_MAP_MAX_COLUMN_NUMBER
+	       /* column exceeds max_column_hint for ord_map.  */
+	       || expected_column > line_width);
+}
+
+/* Subroutine of test_fixit_on_very_long_line.
+   Run various things for RICHLOC, but don't check; we just want them
+   to survive.  */
+
+static void
+test_richloc (rich_location *richloc)
+{
+  /* Run the diagnostic and fix-it printing code.  */
+  test_diagnostic_context dc;
+  diagnostic_show_locus (&dc, richloc, DK_ERROR);
+
+  /* Generate a diff.  */
+  edit_context ec;
+  ec.add_fixits (richloc);
+  char *diff = ec.generate_diff (true);
+  free (diff);
+}
+
+/* Verify that the fix-it-printing code can cope with very long lines
+   (PR c/82050).  */
+
+static void
+test_fixit_on_very_long_line (const line_table_case &case_)
+{
+  /* Various interesting column/line-width values, to try to tickle
+     out bugs.  */
+  const int VERY_LONG_LINE = 8192;
+  const int columns[] = {0,
+			 1,
+			 80,
+			 LINE_MAP_MAX_COLUMN_NUMBER - 2,
+			 LINE_MAP_MAX_COLUMN_NUMBER - 1,
+			 LINE_MAP_MAX_COLUMN_NUMBER,
+			 LINE_MAP_MAX_COLUMN_NUMBER + 1,
+			 LINE_MAP_MAX_COLUMN_NUMBER + 2,
+			 VERY_LONG_LINE,
+			 VERY_LONG_LINE + 5};
+  for (unsigned int width_idx = 0; width_idx < ARRAY_SIZE (columns);
+       width_idx++)
+    {
+      int line_width = columns[width_idx];
+
+      /* Create a source file with a very long line.  */
+      named_temp_file tmp (".c");
+      FILE *f = fopen (tmp.get_filename (), "w");
+      for (int i = 0; i < line_width; i++)
+	fputc (' ', f);
+      fputc ('\n', f);
+      fclose (f);
+
+      line_table_test ltt (case_);
+      const line_map_ordinary *ord_map = linemap_check_ordinary
+	(linemap_add (line_table, LC_ENTER, false, tmp.get_filename (), 0));
+      linemap_line_start (line_table, 1, line_width);
+
+      for (unsigned int start_idx = 0; start_idx < ARRAY_SIZE (columns);
+	   start_idx++)
+	{
+	  int start_col = columns[start_idx];
+	  location_t start_loc
+	    = linemap_position_for_line_and_column (line_table, ord_map, 1,
+						    start_col);
+	  verify_column (start_loc, ord_map, line_width, start_col);
+	  for (unsigned int finish_idx = 0; finish_idx < ARRAY_SIZE (columns);
+	       finish_idx++)
+	    {
+	      int finish_col = columns[finish_idx];
+	      location_t finish_loc
+		= linemap_position_for_line_and_column (line_table, ord_map, 1,
+							finish_col);
+	      verify_column (finish_loc, ord_map, line_width, finish_col);
+
+	      /* Now use start-finish to exercise the fix-it code.
+		 In each case, run the printing code, but don't check;
+		 we just want it to survive.  */
+
+	      /* Insertion.  */
+	      {
+		rich_location richloc (line_table, start_loc);
+		richloc.add_fixit_insert_after (start_loc, "insertion");
+		test_richloc (&richloc);
+	      }
+
+	      /* Replacement.  */
+	      {
+		rich_location richloc (line_table, start_loc);
+		source_range range
+		  = source_range::from_locations (start_loc, finish_loc);
+		richloc.add_fixit_replace (range, "replacement");
+		test_richloc (&richloc);
+	      }
+
+	      /* Deletion.  */
+	      {
+		rich_location richloc (line_table, start_loc);
+		source_range range
+		  = source_range::from_locations (start_loc, finish_loc);
+		richloc.add_fixit_remove (range);
+		test_richloc (&richloc);
+	      }
+	    }
+	}
+    }
+}
+
+/* Callback handler for the PLUGIN_FINISH event.
+   At this point, all GCC subsystems should be initialized and
+   "warmed up"; this is where we run our unit tests.  */
+
+static void
+expensive_tests (void */*gcc_data*/, void */*user_data*/)
+{
+  test_runner r ("expensive_selftests_plugin");
+
+  for_each_line_table_case (test_fixit_on_very_long_line);
+}
+
+} // namespace selftest
+
+#endif /* #if CHECKING_P */
+
+int
+plugin_init (struct plugin_name_args *plugin_info,
+	     struct plugin_gcc_version *version)
+{
+#if CHECKING_P
+  const char *plugin_name = plugin_info->base_name;
+  register_callback (plugin_info->base_name,
+		     PLUGIN_FINISH,
+		     selftest::expensive_tests,
+		     NULL); /* void *user_data */
+  return 0;
+#endif /* #if CHECKING_P */
+}
diff --git a/gcc/testsuite/gcc.dg/plugin/plugin.exp b/gcc/testsuite/gcc.dg/plugin/plugin.exp
index c7a3b4d..ff3c976 100644
--- a/gcc/testsuite/gcc.dg/plugin/plugin.exp
+++ b/gcc/testsuite/gcc.dg/plugin/plugin.exp
@@ -82,6 +82,8 @@ set plugin_test_list [list \
     { must_tail_call_plugin.c \
 	  must-tail-call-1.c \
 	  must-tail-call-2.c } \
+    { expensive_selftests_plugin.c \
+	  expensive-selftests-1.c } \
 ]
 
 foreach plugin_test $plugin_test_list {
-- 
1.8.5.3