[PATCH 1/2] Add function filtering to gcov

[PATCH 1/2] Add function filtering to gcov

[Jørgen Kvalsvik]

Add the --include and --exclude flags to gcov to control what functions
to report on. This is meant to make gcov more practical as an when
writing test suites or performing other coverage experiments, which
tends to focus on a few functions at the time. This really shines in
combination with the -t/--stdout flag. With support for more expansive
metrics in gcov like modified condition/decision coverage (MC/DC) and
path coverage, output quickly gets overwhelming without filtering.

The approach is quite simple: filters are egrep regexes and are
evaluated left-to-right, and the last filter "wins", that is, if a
function matches an --include and a subsequent --exclude, it should not
be included in the output. All of the output machinery works on the
function table, so by optionally (not) adding function makes the even
the json output work as expected, and only minor changes are needed to
suppress the filtered-out functions.

Demo: math.c

    int mul (int a, int b) {
        return a * b;
    }

    int sub (int a, int b) {
        return a - b;
    }

    int sum (int a, int b) {
        return a + b;
    }

Plain matches:

$ gcov -t math --include=sum
        -:    0:Source:filter.c
        -:    0:Graph:filter.gcno
        -:    0:Data:-
        -:    0:Runs:0
    #####:    9:int sum (int a, int b) {
    #####:   10:    return a + b;

$ gcov -t math --include=mul
        -:    0:Source:filter.c
        -:    0:Graph:filter.gcno
        -:    0:Data:-
        -:    0:Runs:0
    #####:    1:int mul (int a, int b) {
    #####:    2:    return a * b;

Regex match:

$ gcov -t math --include=su
        -:    0:Source:filter.c
        -:    0:Graph:filter.gcno
        -:    0:Data:-
        -:    0:Runs:0
    #####:    5:int sub (int a, int b) {
    #####:    6:    return a - b;
        -:    7:}
    #####:    9:int sum (int a, int b) {
    #####:   10:    return a + b;

And similar for exclude:

$ gcov -t math --exclude=sum
        -:    0:Source:filter.c
        -:    0:Graph:filter.gcno
        -:    0:Data:-
        -:    0:Runs:0
    #####:    1:int mul (int a, int b) {
    #####:    2:    return a * b;
        -:    3:}
    #####:    5:int sub (int a, int b) {
    #####:    6:    return a - b;

And json, for good measure:

$ gcov -t math --include=sum --json | jq ".files[].lines[]"
{
  "line_number": 9,
  "function_name": "sum",
  "count": 0,
  "unexecuted_block": true,
  "block_ids": [],
  "branches": [],
  "calls": []
}
{
  "line_number": 10,
  "function_name": "sum",
  "count": 0,
  "unexecuted_block": true,
  "block_ids": [
    2
  ],
  "branches": [],
  "calls": []
}

Note that the last function gets "clipped" when lines are associated to
functions, which means the closing brace is dropped from the report. I
hope this can be fixed, but considering it is not really a part of the
function body, the gcov report is "complete".

Matching generally work well for mangled names, as the mangled names
also have the base symbol name in it. By default, functions are matched
by the mangled name, which means matching on base names always work as
expected. The -M flag makes the matching work on the demangled name
which is quite useful when you only want to report on specific
overloads and can use the full type names.

Why not just use grep? grep is not really sufficient as grep is very
line oriented, and the reports that benefit the most from filtering
often unpredictably span multiple lines based on the state of coverage.
For example, a condition coverage report for 3 terms/6 outcomes only
outputs 1 line when all conditions are covered, and 7 with no lines
covered.

gcc/ChangeLog:

	* doc/gcov.texi: Add --include, --exclude, --match-on-demangled
	documentation.
	* gcov.cc (struct fnfilter): New.
	(print_usage): Add --include, --exclude, -M,
	--match-on-demangled.
	(process_args): Likewise.
	(release_structures): Release filters.
	(read_graph_file): Only add function_infos matching filters.
	(output_lines): Likewise.

gcc/testsuite/ChangeLog:

	* lib/gcov.exp: Add filtering test function.
	* g++.dg/gcov/gcov-19.C: New test.
	* g++.dg/gcov/gcov-20.C: New test.
	* g++.dg/gcov/gcov-21.C: New test.
	* gcc.misc-tests/gcov-25.c: New test.
	* gcc.misc-tests/gcov-26.c: New test.
	* gcc.misc-tests/gcov-27.c: New test.
	* gcc.misc-tests/gcov-28.c: New test.
---
 gcc/doc/gcov.texi                      |  27 ++++++
 gcc/gcov.cc                            | 128 +++++++++++++++++++++++--
 gcc/testsuite/g++.dg/gcov/gcov-19.C    |  35 +++++++
 gcc/testsuite/g++.dg/gcov/gcov-20.C    |  38 ++++++++
 gcc/testsuite/g++.dg/gcov/gcov-21.C    |  32 +++++++
 gcc/testsuite/gcc.misc-tests/gcov-25.c |  25 +++++
 gcc/testsuite/gcc.misc-tests/gcov-26.c |  25 +++++
 gcc/testsuite/gcc.misc-tests/gcov-27.c |  24 +++++
 gcc/testsuite/gcc.misc-tests/gcov-28.c |  22 +++++
 gcc/testsuite/lib/gcov.exp             |  53 +++++++++-
 10 files changed, 398 insertions(+), 11 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/gcov/gcov-19.C
 create mode 100644 gcc/testsuite/g++.dg/gcov/gcov-20.C
 create mode 100644 gcc/testsuite/g++.dg/gcov/gcov-21.C
 create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-25.c
 create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-26.c
 create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-27.c
 create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-28.c

diff --git a/gcc/doc/gcov.texi b/gcc/doc/gcov.texi
index c118061aed5..a9690bf5a69 100644
--- a/gcc/doc/gcov.texi
+++ b/gcc/doc/gcov.texi
@@ -127,11 +127,14 @@ gcov [@option{-v}|@option{--version}] [@option{-h}|@option{--help}]
      [@option{-g}|@option{--conditions}]
      [@option{-d}|@option{--display-progress}]
      [@option{-f}|@option{--function-summaries}]
+     [@option{--include} @var{regex}]
+     [@option{--exclude} @var{regex}]
      [@option{-j}|@option{--json-format}]
      [@option{-H}|@option{--human-readable}]
      [@option{-k}|@option{--use-colors}]
      [@option{-l}|@option{--long-file-names}]
      [@option{-m}|@option{--demangled-names}]
+     [@option{-M}|@option{--filter-on-demangled}]
      [@option{-n}|@option{--no-output}]
      [@option{-o}|@option{--object-directory} @var{directory|file}]
      [@option{-p}|@option{--preserve-paths}]
@@ -186,6 +189,24 @@ Display the progress on the standard output.
 @itemx --function-summaries
 Output summaries for each function in addition to the file level summary.
 
+@item --include @var{regex}
+Include functions matching @var{regex}.  This option makes
+@command{gcov} only report on functions that match the extended
+regular expression @var{regex}.  This flag can be combined with
+@option{--exclude}.  If a function matches both includes and excludes,
+the last include/exclude applies.  By default @command{gcov} reports
+on all functions, but if a @command{--include} is used then only
+functions matching the include will be reported.
+
+@item --exclude @var{regex}
+Exclude functions matching @var{regex}.  This option makes
+@command{gcov} not report on functions that match the extended regular
+expression @var{regex}.  This flag can be combined with
+@option{--include}.  If a function matches both includes and excludes,
+the last include/exclude applies.  By default @command{gcov} reports
+on all functions, and if @option{--exclude} is used then functions
+matching it will be omitted.
+
 @item -h
 @itemx --help
 Display help about using @command{gcov} (on the standard output), and
@@ -449,6 +470,12 @@ and included file names will be complete path names.
 Display demangled function names in output. The default is to show
 mangled function names.
 
+@item -M
+@itemx --filter-on-demangled
+Make @option{--include} and @option{--exclude} match demangled names.
+This does only affects the matching and does not imply
+@option{--demangled-names}, but it can safely be combined with it.
+
 @item -n
 @itemx --no-output
 Do not create the @command{gcov} output file.
diff --git a/gcc/gcov.cc b/gcc/gcov.cc
index 0d4ef14e6c9..f6787f0be8f 100644
--- a/gcc/gcov.cc
+++ b/gcc/gcov.cc
@@ -47,10 +47,10 @@ along with Gcov; see the file COPYING3.  If not see
 #include "pretty-print.h"
 #include "json.h"
 #include "hwint.h"
+#include "xregex.h"
 
 #include <zlib.h>
 #include <getopt.h>
-
 #include "md5.h"
 
 using namespace std;
@@ -683,6 +683,48 @@ static int flag_counts = 0;
 /* Return code of the tool invocation.  */
 static int return_code = 0;
 
+/* "Keep policy" when adding functions to the global function table.  This will
+   be set to false when --include is used, otherwise every function should be
+   added to the table.  Used for --include/exclude.  */
+static bool default_keep = true;
+
+/* Include/exclude filters function based on matching the (de)mangled name.
+   The default is to match the mangled name.  Note that flag_demangled_names
+   does not affect this.  */
+static bool flag_filter_on_demangled = false;
+
+/* A 'function filter', a filter and action for determining if a function
+   should be included in the output or not.  Used for --include/--exclude
+   filtering.  */
+struct fnfilter
+{
+  /* The (extended) compiled regex for this filter.  */
+  regex_t regex;
+
+  /* The action when this filter (regex) matches - if true, the function should
+     be kept, otherwise discarded.  */
+  bool keep;
+
+  /* Compile the regex EXPR, or exit if pattern is malformed.  */
+  void compile (const char *expr)
+  {
+    int err = regcomp (&regex, expr, REG_NOSUB | REG_EXTENDED);
+    if (err)
+      {
+	size_t len = regerror (err, &regex, nullptr, 0);
+	char *msg = XNEWVEC (char, len);
+	regerror (err, &regex, msg, len);
+	fprintf (stderr, "Bad regular expression: %s\n", msg);
+	free (msg);
+	exit (EXIT_FAILURE);
+    }
+  }
+};
+
+/* A collection of filter functions for including/exclude functions in the
+   output.  This is empty unless --include/--exclude is used.  */
+static vector<fnfilter> filters;
+
 /* Forward declarations.  */
 static int process_args (int, char **);
 static void print_usage (int) ATTRIBUTE_NORETURN;
@@ -977,6 +1019,8 @@ print_usage (int error_p)
   fnotice (file, "  -d, --display-progress          Display progress information\n");
   fnotice (file, "  -D, --debug			    Display debugging dumps\n");
   fnotice (file, "  -f, --function-summaries        Output summaries for each function\n");
+  fnotice (file, "      --include                   Include functions matching this regex\n");
+  fnotice (file, "      --exclude                   Exclude functions matching this regex\n");
   fnotice (file, "  -h, --help                      Print this help, then exit\n");
   fnotice (file, "  -j, --json-format               Output JSON intermediate format\n\
                                     into .gcov.json.gz file\n");
@@ -985,6 +1029,8 @@ print_usage (int error_p)
   fnotice (file, "  -l, --long-file-names           Use long output file names for included\n\
                                     source files\n");
   fnotice (file, "  -m, --demangled-names           Output demangled function names\n");
+  fnotice (file, "  -M, --filter-on-demangled       Make --include/--exclude match on demangled\n\
+                                    names. This does not imply -m\n");
   fnotice (file, "  -n, --no-output                 Do not create an output file\n");
   fnotice (file, "  -o, --object-directory DIR|FILE Search for object files in DIR or called FILE\n");
   fnotice (file, "  -p, --preserve-paths            Preserve all pathname components\n");
@@ -1029,11 +1075,14 @@ static const struct option options[] =
   { "branch-counts",        no_argument,       NULL, 'c' },
   { "conditions",	    no_argument,       NULL, 'g' },
   { "json-format",	    no_argument,       NULL, 'j' },
+  { "include",              required_argument, NULL, 'I' },
+  { "exclude",              required_argument, NULL, 'E' },
   { "human-readable",	    no_argument,       NULL, 'H' },
   { "no-output",            no_argument,       NULL, 'n' },
   { "long-file-names",      no_argument,       NULL, 'l' },
   { "function-summaries",   no_argument,       NULL, 'f' },
   { "demangled-names",      no_argument,       NULL, 'm' },
+  { "filter-on-demangled",  no_argument,       NULL, 'M' },
   { "preserve-paths",       no_argument,       NULL, 'p' },
   { "relative-only",        no_argument,       NULL, 'r' },
   { "object-directory",     required_argument, NULL, 'o' },
@@ -1056,7 +1105,7 @@ process_args (int argc, char **argv)
 {
   int opt;
 
-  const char *opts = "abcdDfghHijklmno:pqrs:tuvwx";
+  const char *opts = "abcdDfghHijklmMno:pqrs:tuvwx";
   while ((opt = getopt_long (argc, argv, opts, options, NULL)) != -1)
     {
       switch (opt)
@@ -1082,6 +1131,17 @@ process_args (int argc, char **argv)
 	case 'l':
 	  flag_long_names = 1;
 	  break;
+	case 'I':
+	  default_keep = false;
+	  filters.push_back (fnfilter {});
+	  filters.back ().keep = true;
+	  filters.back ().compile (optarg);
+	  break;
+	case 'E':
+	  filters.push_back (fnfilter {});
+	  filters.back ().keep = false;
+	  filters.back ().compile (optarg);
+	  break;
 	case 'H':
 	  flag_human_readable_numbers = 1;
 	  break;
@@ -1094,6 +1154,9 @@ process_args (int argc, char **argv)
 	case 'm':
 	  flag_demangled_names = 1;
 	  break;
+	case 'M':
+	  flag_filter_on_demangled = true;
+	  break;
 	case 'n':
 	  flag_gcov_file = 0;
 	  break;
@@ -1728,9 +1791,13 @@ release_structures (void)
        it != functions.end (); it++)
     delete (*it);
 
+  for (fnfilter &filter : filters)
+    regfree (&filter.regex);
+
   sources.resize (0);
   names.resize (0);
   functions.resize (0);
+  filters.resize (0);
   ident_to_fn.clear ();
 }
 
@@ -1955,8 +2022,6 @@ read_graph_file (void)
 	  unsigned end_column = gcov_read_unsigned ();
 
 	  fn = new function_info ();
-	  functions.push_back (fn);
-	  ident_to_fn[ident] = fn;
 
 	  fn->m_name = function_name;
 	  fn->ident = ident;
@@ -1970,6 +2035,26 @@ read_graph_file (void)
 	  fn->artificial = artificial;
 
 	  current_tag = tag;
+
+	  /* This is separate from flag_demangled_names to support filtering on
+	     mangled names while printing demangled names, or filtering on
+	     demangled names while printing mangled names.  An independent flag
+	     makes sure the function selection does not change even if
+	     demangling is turned on/off.  */
+	  const char *fname = function_name;
+	  if (flag_filter_on_demangled)
+	    fname = fn->get_demangled_name ();
+
+	  bool keep = default_keep;
+	  for (const fnfilter &fn : filters)
+	    if (regexec (&fn.regex, fname, 0, nullptr, 0) == 0)
+	      keep = fn.keep;
+
+	  if (keep)
+	    {
+	      functions.push_back (fn);
+	      ident_to_fn[ident] = fn;
+	    }
 	}
       else if (fn && tag == GCOV_TAG_BLOCKS)
 	{
@@ -3377,11 +3462,17 @@ output_lines (FILE *gcov_file, const source_info *src)
 
   unsigned line_start_group = 0;
   vector<function_info *> *fns;
+  unsigned filtered_line_end = !filters.empty () ? 0 : source_lines.size ();
 
   for (unsigned line_num = 1; line_num <= source_lines.size (); line_num++)
     {
       if (line_num >= src->lines.size ())
 	{
+	  /* If the src->lines is truncated because the rest of the functions
+	     are filtered out we must stop here, and not fall back to printing
+	     the rest of the file.  */
+	  if (!filters.empty ())
+	    break;
 	  fprintf (gcov_file, "%9s:%5u", "-", line_num);
 	  print_source_line (gcov_file, source_lines, line_num);
 	  continue;
@@ -3400,11 +3491,26 @@ output_lines (FILE *gcov_file, const source_info *src)
 	      for (unsigned i = 0; i < fns->size (); i++)
 		if ((*fns)[i]->end_line > line_start_group)
 		  line_start_group = (*fns)[i]->end_line;
+
+	      /* When filtering, src->lines will be cut short for the last
+		 selected function.  To make sure the "overlapping function"
+		 section is printed too, adjust the end so that it is within
+		 src->lines.  */
+	      if (line_start_group >= src->lines.size ())
+		line_start_group = src->lines.size () - 1;
+
+	      if (!filters.empty ())
+		filtered_line_end = line_start_group;
 	    }
 	  else if (fns != NULL && fns->size () == 1)
 	    {
 	      function_info *fn = (*fns)[0];
 	      output_function_details (gcov_file, fn);
+
+	      /* If functions are filtered, only the matching functions will be in
+		 fns and there is no need for extra checking.  */
+	      if (!filters.empty ())
+		filtered_line_end = fn->end_line;
 	    }
 	}
 
@@ -3414,12 +3520,16 @@ output_lines (FILE *gcov_file, const source_info *src)
 	 Otherwise, print the execution count before the source line.
 	 There are 16 spaces of indentation added before the source
 	 line so that tabs won't be messed up.  */
-      output_line_beginning (gcov_file, line->exists, line->unexceptional,
-			     line->has_unexecuted_block, line->count,
-			     line_num, "=====", "#####", src->maximum_count);
+      if (line_num <= filtered_line_end)
+	{
+	  output_line_beginning (gcov_file, line->exists, line->unexceptional,
+				 line->has_unexecuted_block, line->count,
+				 line_num, "=====", "#####",
+				 src->maximum_count);
 
-      print_source_line (gcov_file, source_lines, line_num);
-      output_line_details (gcov_file, line, line_num);
+	  print_source_line (gcov_file, source_lines, line_num);
+	  output_line_details (gcov_file, line, line_num);
+	}
 
       if (line_start_group == line_num)
 	{
diff --git a/gcc/testsuite/g++.dg/gcov/gcov-19.C b/gcc/testsuite/g++.dg/gcov/gcov-19.C
new file mode 100644
index 00000000000..3f898cfae4b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gcov/gcov-19.C
@@ -0,0 +1,35 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+/* Filtering on the function base name generally works well, because it becomes
+   an unadultered part of the symbol.  */
+
+template <typename T>
+T
+fn1 (T x)
+{
+  /* fst */
+  return x;
+}
+
+template <typename T>
+T
+fn2 (T x)
+{
+  /* snd */
+  return 2 * x;
+}
+
+int
+main ()
+{
+  fn1 (2);
+  fn1 (2.0);
+  fn1 (2.0f);
+
+  fn2 (2);
+  fn2 (2.0);
+  fn2 (2.0f);
+}
+
+/* { dg-final { run-gcov { filters { fn1 } { fn2 } } { --include=fn1 gcov-19.C } } } */
diff --git a/gcc/testsuite/g++.dg/gcov/gcov-20.C b/gcc/testsuite/g++.dg/gcov/gcov-20.C
new file mode 100644
index 00000000000..fb33f7ecbdd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gcov/gcov-20.C
@@ -0,0 +1,38 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+/* Filtering also works by targeting the mangled symbol directly, but the
+   subtlety is not really caught by the test framework.  Matching on fn1I[df]
+   prints the "overlapping blocks" of both the float and double instantiation,
+   but *not* the int instantiation.  The extra {} around the --include argument
+   is quoting for tcl/dejagnu.  */
+
+template <typename T>
+T
+fn1 (T x)
+{
+  /* fst */
+  return x;
+}
+
+template <typename T>
+T
+fn2 (T x)
+{
+  /* snd */
+  return 2 * x;
+}
+
+int
+main ()
+{
+  fn1 (2);
+  fn1 (2.0);
+  fn1 (2.0f);
+
+  fn2 (2);
+  fn2 (2.0);
+  fn2 (2.0f);
+}
+
+/* { dg-final { run-gcov { filters { fst } { snd } } { {--include=fn1I[fd]} gcov-20.C } } } */
diff --git a/gcc/testsuite/g++.dg/gcov/gcov-21.C b/gcc/testsuite/g++.dg/gcov/gcov-21.C
new file mode 100644
index 00000000000..67f6d79dbf1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gcov/gcov-21.C
@@ -0,0 +1,32 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+/* Filters can be applied to demangled names. This support matching on
+   types and class hierarchies as well as function names.  */
+
+template <typename T>
+T
+fn1 (T x)
+{
+  /* fst */
+  return x;
+}
+
+template <typename T>
+T
+fn2 (T x)
+{
+  /* snd */
+  return 2 * x;
+}
+
+int
+main ()
+{
+  fn1 (2);
+
+  fn2 (2.0);
+  fn2 (2.0f);
+}
+
+/* { dg-final { run-gcov { filters { fst } } { --filter-on-demangled --include int gcov-21.C } } } */
diff --git a/gcc/testsuite/gcc.misc-tests/gcov-25.c b/gcc/testsuite/gcc.misc-tests/gcov-25.c
new file mode 100644
index 00000000000..658f375e055
--- /dev/null
+++ b/gcc/testsuite/gcc.misc-tests/gcov-25.c
@@ -0,0 +1,25 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+/* Filters are considered in order with latest-wins, so if a function is
+   included and later excluded it should not show up.  */
+
+int
+fn1 (int x)
+{
+  /* fst */
+  return x;
+}
+
+int
+fn2 (int x)
+{
+  /* snd */
+  return x * 2;
+}
+
+int
+main ()
+{}
+
+/* { dg-final { run-gcov { filters { snd } { fst main } } { --include=fn --exclude=1 gcov-25.c } } } */
diff --git a/gcc/testsuite/gcc.misc-tests/gcov-26.c b/gcc/testsuite/gcc.misc-tests/gcov-26.c
new file mode 100644
index 00000000000..d204cd3c72b
--- /dev/null
+++ b/gcc/testsuite/gcc.misc-tests/gcov-26.c
@@ -0,0 +1,25 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+/* Filters are considered in order with latest-wins, so if a function is
+   excluded and later included it should show up.  */
+
+int
+fn1 (int x)
+{
+  /* fst */
+  return x;
+}
+
+int
+fn2 (int x)
+{
+  /* snd */
+  return x * 2;
+}
+
+int
+main ()
+{}
+
+/* { dg-final { run-gcov { filters { fst snd } { main } } { --exclude=1 --include=fn gcov-26.c } } } */
diff --git a/gcc/testsuite/gcc.misc-tests/gcov-27.c b/gcc/testsuite/gcc.misc-tests/gcov-27.c
new file mode 100644
index 00000000000..e01a2c794a7
--- /dev/null
+++ b/gcc/testsuite/gcc.misc-tests/gcov-27.c
@@ -0,0 +1,24 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+/* If only --exclude is used, other functions should be used by default.  */
+
+int
+fn1 (int x)
+{
+  /* fst */
+  return x;
+}
+
+int
+fn2 (int x)
+{
+  /* snd */
+  return x * 2;
+}
+
+int
+main ()
+{}
+
+/* { dg-final { run-gcov { filters { fst snd } { main } } { --exclude=main gcov-27.c } } } */
diff --git a/gcc/testsuite/gcc.misc-tests/gcov-28.c b/gcc/testsuite/gcc.misc-tests/gcov-28.c
new file mode 100644
index 00000000000..26f5b15e06f
--- /dev/null
+++ b/gcc/testsuite/gcc.misc-tests/gcov-28.c
@@ -0,0 +1,22 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+int
+once (int x)
+{
+  /* fst */
+  return x;
+}
+
+int
+twice (int x)
+{
+  /* snd */
+  return x * 2;
+}
+
+int
+main ()
+{}
+
+/* { dg-final { run-gcov { filters { fst } { snd main } } { --include=once gcov-28.c } } } */
diff --git a/gcc/testsuite/lib/gcov.exp b/gcc/testsuite/lib/gcov.exp
index dd47d66d1b2..e49f1011884 100644
--- a/gcc/testsuite/lib/gcov.exp
+++ b/gcc/testsuite/lib/gcov.exp
@@ -495,6 +495,44 @@ proc verify-calls { testname testcase file } {
     return $failed
 }
 
+# Verify that report filtering includes and excludes the right functions.
+proc verify-filters { testname testcase file expected unexpected } {
+    set fd [open $file r]
+
+    set seen {}
+    set ex [concat $expected $unexpected]
+
+    while { [gets $fd line] >= 0 } {
+	foreach sym $ex {
+	    if [regexp "$sym" "$line"] {
+		lappend seen $sym
+	    }
+	}
+    }
+
+    set seen [lsort -unique $seen]
+
+    set expected [lmap key $expected {
+	if { $key in $seen } continue
+	set key
+    }]
+    set unexpected [lmap key $unexpected {
+	if { $key ni $seen } continue
+	set key
+    }]
+
+    foreach sym $expected {
+	fail "Did not see expected symbol '$sym'"
+    }
+
+    foreach sym $unexpected {
+	fail "Found unexpected symbol '$sym'"
+    }
+
+    close $fd
+    return [expr [llength $expected] + [llength $unexpected]]
+}
+
 proc gcov-pytest-format-line { args } {
     global subdir
 
@@ -570,6 +608,7 @@ proc run-gcov { args } {
     set gcov_verify_conditions 0
     set gcov_verify_lines 1
     set gcov_verify_intermediate 0
+    set gcov_verify_filters 0
     set gcov_remove_gcda 0
     set xfailed 0
 
@@ -580,12 +619,17 @@ proc run-gcov { args } {
 	  set gcov_verify_branches 1
 	} elseif { $a == "conditions" } {
 	  set gcov_verify_conditions 1
+	} elseif { [lindex $a 0] == "filters" } {
+	  set gcov_verify_filters 1
+	  set verify_filters_expected [lindex $a 1]
+	  set verify_filters_unexpected [lindex $a 2]
 	} elseif { $a == "intermediate" } {
 	  set gcov_verify_intermediate 1
 	  set gcov_verify_calls 0
 	  set gcov_verify_branches 0
 	  set gcov_verify_conditions 0
 	  set gcov_verify_lines 0
+	  set gcov_verify_filters 0
 	} elseif { $a == "remove-gcda" } {
 	  set gcov_remove_gcda 1
 	} elseif { $gcov_args == "" } {
@@ -670,15 +714,20 @@ proc run-gcov { args } {
     } else {
 	set ifailed 0
     }
+    if { $gcov_verify_filters } {
+	set ffailed [verify-filters $testname $testcase $testcase.gcov $verify_filters_expected $verify_filters_unexpected]
+    } else {
+	set ffailed 0
+    }
 
     # Report whether the gcov test passed or failed.  If there were
     # multiple failures then the message is a summary.
-    set tfailed [expr $lfailed + $bfailed + $cdfailed + $cfailed + $ifailed]
+    set tfailed [expr $lfailed + $bfailed + $cdfailed + $cfailed + $ifailed + $ffailed]
     if { $xfailed } {
 	setup_xfail "*-*-*"
     }
     if { $tfailed > 0 } {
-	fail "$testname gcov: $lfailed failures in line counts, $bfailed in branch percentages, $cdfailed in condition/decision, $cfailed in return percentages, $ifailed in intermediate format"
+	fail "$testname gcov: $lfailed failures in line counts, $bfailed in branch percentages, $cdfailed in condition/decision, $cfailed in return percentages, $ifailed in intermediate format, $ffailed failed in filters"
 	if { $xfailed } {
 	    clean-gcov $testcase
 	}
-- 
2.30.2

[PATCH 2/2] Add examples on filteirng in gcov tutorial

[Jørgen Kvalsvik]

Add a section with some examples on the --include and --exclude flags in
the gcov tutorial.

gcc/ChangeLog:

	* doc/gcov.texi: Add tutorial on function filtering.
---
 gcc/doc/gcov.texi | 86 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)

diff --git a/gcc/doc/gcov.texi b/gcc/doc/gcov.texi
index a9690bf5a69..dc79bccb8cf 100644
--- a/gcc/doc/gcov.texi
+++ b/gcc/doc/gcov.texi
@@ -933,6 +933,92 @@ the file doesn't match the executable (differing number of basic block
 counts) it will ignore the contents of the file.  It then adds in the
 new execution counts and finally writes the data to the file.
 
+You can report on a subset of functions by using @option{--include}
+and @option{--exclude}.  This is very useful when combined with
+@option{--stdout} trying to understand behavior and coverage for a
+particular function by running a test, looking at @command{gcov}
+output, testing another input, and running @command{gcov} again.
+
+@smallexample
+$ gcov -m --stdout --include inc tmp
+        -:    0:Source:tmp.cpp
+        -:    0:Graph:tmp.gcno
+        -:    0:Data:tmp.gcda
+        -:    0:Runs:1
+       2*:    8:  void inc () @{ b++; @}
+------------------
+Foo<char>::inc():
+    #####:    8:  void inc () @{ b++; @}
+------------------
+Foo<int>::inc():
+        2:    8:  void inc () @{ b++; @}
+------------------
+@end smallexample
+
+@command{gcov} will match on mangled names by default, which you can
+control with the @option{-M} flag.  Note that matching and reporting
+are independent, so you can match on mangled names while printing
+demangled names, and vice versa.  To report on the @code{int}
+instantiation of @code{Foo} matching on mangled and demangled names:
+
+@smallexample
+$ gcov -t -m -M tmp --include 'Foo<int>'
+        -:    0:Source:tmp.cpp
+        -:    0:Graph:tmp.gcno
+        -:    0:Data:tmp.gcda
+        -:    0:Runs:1
+        1:    7:  Foo(): b (1000) @{@}
+        2:    8:  void inc () @{ b++; @}
+@end smallexample
+
+@smallexample
+$ gcov -t -m tmp --include 'FooIi'
+        -:    0:Source:tmp.cpp
+        -:    0:Graph:tmp.gcno
+        -:    0:Data:tmp.gcda
+        -:    0:Runs:1
+        1:    7:  Foo(): b (1000) @{@}
+        2:    8:  void inc () @{ b++; @}
+@end smallexample
+
+The arguments to @option{--include} and @option{--exclude} are
+extended regular expressions (like @command{grep -E}), so the pattern
+@code{in.?} matches both @code{inc} and @code{main}.  If used with
+@option{-M} then all @code{int} instantiations of @code{Foo} would
+match too.  @option{--include} and @option{--exclude} can be used
+multiple times, and if a name matches multiple filters it is the last
+one to match which takes preference.  For example, to match
+@code{main} and the @code{int} instatiation of @code{inc}, while
+omitting the @code{Foo} constructor:
+
+@smallexample
+$ gcov -t -m -M --include in --exclude Foo --include '<int>::inc' tmp
+        -:    0:Source:tmp.cpp
+        -:    0:Graph:tmp.gcno
+        -:    0:Data:tmp.gcda
+        -:    0:Runs:1
+        2:    8:  void inc () @{ b++; @}
+        1:   18:main (void)
+        -:   19:@{
+        -:   20:  int i, total;
+        1:   21:  Foo<int> counter;
+        -:   22:
+        1:   23:  counter.inc();
+        1:   24:  counter.inc();
+        1:   25:  total = 0;
+        -:   26:
+       11:   27:  for (i = 0; i < 10; i++)
+       10:   28:    total += i;
+        -:   29:
+       1*:   30:  int v = total > 100 ? 1 : 2;
+        -:   31:
+        1:   32:  if (total != 45)
+    #####:   33:    printf ("Failure\n");
+        -:   34:  else
+        1:   35:    printf ("Success\n");
+        1:   36:  return 0;
+@end smallexample
+
 @node Gcov and Optimization
 @section Using @command{gcov} with GCC Optimization
 
-- 
2.30.2