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From: "Jørgen Kvalsvik" <jorgen.kvalsvik@woven-planet.global>
To: gcc-patches@gcc.gnu.org
Subject: [Ping 2][PATCH] Add condition coverage profiling
Date: Wed, 9 Nov 2022 21:08:20 +0100	[thread overview]
Message-ID: <ab60df61-97c3-1ee6-279f-ed3f44350201@woven-planet.global> (raw)
In-Reply-To: <73dbc82b-392f-aa02-6db2-9c201de85f96@woven-planet.global>

On 02/11/2022 07:16, Jørgen Kvalsvik wrote:
> On 25/10/2022 08:33, Jørgen Kvalsvik wrote:
>> On 12/10/2022 12:16, Jørgen Kvalsvik wrote:
>>> This patch adds support in gcc+gcov for modified condition/decision
>>> coverage (MC/DC) with the -fprofile-conditions flag. MC/DC is a type of
>>> test/code coverage and it is particularly important in the avation and
>>> automotive industries for safety-critical applications. MC/DC it is
>>> required for or recommended by:
>>>
>>>     * DO-178C for the most critical software (Level A) in avionics
>>>     * IEC 61508 for SIL 4
>>>     * ISO 26262-6 for ASIL D
>>>
>>> From the SQLite webpage:
>>>
>>>     Two methods of measuring test coverage were described above:
>>>     "statement" and "branch" coverage. There are many other test
>>>     coverage metrics besides these two. Another popular metric is
>>>     "Modified Condition/Decision Coverage" or MC/DC. Wikipedia defines
>>>     MC/DC as follows:
>>>
>>>         * Each decision tries every possible outcome.
>>>         * Each condition in a decision takes on every possible outcome.
>>>         * Each entry and exit point is invoked.
>>>         * Each condition in a decision is shown to independently affect
>>>           the outcome of the decision.
>>>
>>>     In the C programming language where && and || are "short-circuit"
>>>     operators, MC/DC and branch coverage are very nearly the same thing.
>>>     The primary difference is in boolean vector tests. One can test for
>>>     any of several bits in bit-vector and still obtain 100% branch test
>>>     coverage even though the second element of MC/DC - the requirement
>>>     that each condition in a decision take on every possible outcome -
>>>     might not be satisfied.
>>>
>>>     https://sqlite.org/testing.html#mcdc
>>>
>>> Wahlen, Heimdahl, and De Silva "Efficient Test Coverage Measurement for
>>> MC/DC" describes an algorithm for adding instrumentation by carrying
>>> over information from the AST, but my algorithm analyses the the control
>>> flow graph to instrument for coverage. This has the benefit of being
>>> programming language independent and faithful to compiler decisions
>>> and transformations, although I have only tested it on constructs in C
>>> and C++, see testsuite/gcc.misc-tests and testsuite/g++.dg.
>>>
>>> Like Wahlen et al this implementation records coverage in fixed-size
>>> bitsets which gcov knows how to interpret. This is very fast, but
>>> introduces a limit on the number of terms in a single boolean
>>> expression, the number of bits in a gcov_unsigned_type (which is
>>> typedef'd to uint64_t), so for most practical purposes this would be
>>> acceptable. This limitation is in the implementation and not the
>>> algorithm, so support for more conditions can be added by also
>>> introducing arbitrary-sized bitsets.
>>>
>>> For space overhead, the instrumentation needs two accumulators
>>> (gcov_unsigned_type) per condition in the program which will be written
>>> to the gcov file. In addition, every function gets a pair of local
>>> accumulators, but these accmulators are reused between conditions in the
>>> same function.
>>>
>>> For time overhead, there is a zeroing of the local accumulators for
>>> every condition and one or two bitwise operation on every edge taken in
>>> the an expression.
>>>
>>> In action it looks pretty similar to the branch coverage. The -g short
>>> opt carries no significance, but was chosen because it was an available
>>> option with the upper-case free too.
>>>
>>> gcov --conditions:
>>>
>>>         3:   17:void fn (int a, int b, int c, int d) {
>>>         3:   18:    if ((a && (b || c)) && d)
>>> condition outcomes covered 3/8
>>> condition  0 not covered (true false)
>>> condition  1 not covered (true)
>>> condition  2 not covered (true)
>>> condition  3 not covered (true)
>>>         1:   19:        x = 1;
>>>         -:   20:    else
>>>         2:   21:        x = 2;
>>>         3:   22:}
>>>
>>> gcov --conditions --json-format:
>>>
>>>     "conditions": [
>>>         {
>>>             "not_covered_false": [
>>>                 0
>>>             ],
>>>             "count": 8,
>>>             "covered": 3,
>>>             "not_covered_true": [
>>>                 0,
>>>                 1,
>>>                 2,
>>>                 3
>>>             ]
>>>         }
>>>     ],
>>>
>>> Some expressions, mostly those without else-blocks, are effectively
>>> "rewritten" in the CFG construction making the algorithm unable to
>>> distinguish them:
>>>
>>> and.c:
>>>
>>>     if (a && b && c)
>>>         x = 1;
>>>
>>> ifs.c:
>>>
>>>     if (a)
>>>         if (b)
>>>             if (c)
>>>                 x = 1;
>>>
>>> gcc will build the same graph for both these programs, and gcov will
>>> report boths as 3-term expressions. It is vital that it is not
>>> interpreted the other way around (which is consistent with the shape of
>>> the graph) because otherwise the masking would be wrong for the and.c
>>> program which is a more severe error. While surprising, users would
>>> probably expect some minor rewriting of semantically-identical
>>> expressions.
>>>
>>> and.c.gcov:
>>>     #####:    2:    if (a && b && c)
>>> decisions covered 6/6
>>>     #####:    3:        x = 1;
>>>
>>> ifs.c.gcov:
>>>     #####:    2:    if (a)
>>>     #####:    3:        if (b)
>>>     #####:    4:            if (c)
>>>     #####:    5:                x = 1;
>>> condition outcomes covered 6/6
>>>
>>> Adding else clauses alters the program (ifs.c can have 3 elses, and.c
>>> only 1) and coverage becomes less surprising
>>>
>>> ifs.c.gcov:
>>>     #####:    2:    if (a)
>>> condition outcomes covered 2/2
>>>     #####:    4:    {
>>>     #####:    4:        if (b)
>>> condition outcomes covered 2/2
>>>               5:        {
>>>     #####:    6:            if (c)
>>> condition outcomes covered 2/2
>>>     #####:    7:                x = 1;
>>>     #####:    8:        }
>>>     #####:    9:        else
>>>     #####:   10:            x = 2;
>>>     #####:   11:    }
>>>     #####:   12:    else
>>>     #####:   13:        x = 3;
>>>
>>> Since the algorithm works on CFGs, it cannot detect some ternary
>>> operator introduced conditionals. For example, int x = a ? 0 : 1 in
>>> gimple becomes _x = (_a == 0). From source you would expect coverage,
>>> but it gets neither branch nor condition coverage. For completeness, it
>>> could be achieved by scanning all gimple statements for such
>>> comparisons, and insert an extra instruction for recording the outcome.
>>>
>>> The test suite contains a lot of small programs functions. Some of these
>>> were designed by hand to test for specific behaviours and graph shapes,
>>> and some are previously-failed test cases in other programs adapted into
>>> the test suite.
>>>
>>> Alternative author email: Jørgen Kvalsvik <j@lambda.is>
>>>
>>> gcc/ChangeLog:
>>>
>>> 	* builtins.cc (expand_builtin_fork_or_exec): Check
>>> 	profile_condition_flag.
>>> 	* collect2.cc (main): Add -fno-profile-conditions to OBSTACK.
>>> 	* common.opt: Add new options -fprofile-conditions and
>>> 	* doc/gcov.texi: Add --conditions documentation.
>>> 	* doc/invoke.texi: Add -fprofile-conditions documentation.
>>> 	* gcc.cc: Link gcov on -fprofile-conditions.
>>> 	* gcov-counter.def (GCOV_COUNTER_CONDS): New.
>>> 	* gcov-dump.cc (tag_conditions): New.
>>> 	* gcov-io.h (GCOV_TAG_CONDS): New.
>>> 	(GCOV_TAG_CONDS_LENGTH): Likewise.
>>> 	(GCOV_TAG_CONDS_NUM): Likewise.
>>> 	* gcov.cc (class condition_info): New.
>>> 	(condition_info::condition_info): New.
>>> 	(condition_info::popcount): New.
>>> 	(struct coverage_info): New.
>>> 	(add_condition_counts): New.
>>> 	(output_conditions): New.
>>> 	(print_usage): Add -g, --conditions.
>>> 	(process_args): Likewise.
>>> 	(output_intermediate_json_line): Output conditions.
>>> 	(read_graph_file): Read conditions counters.
>>> 	(read_count_file): Read conditions counters.
>>> 	(file_summary): Print conditions.
>>> 	(accumulate_line_info): Accumulate conditions.
>>> 	(output_line_details): Print conditions.
>>> 	* ipa-inline.cc (can_early_inline_edge_p): Check
>>> 	profile_condition_flag.
>>> 	* ipa-split.cc (pass_split_functions::gate): Likewise.
>>> 	* passes.cc (finish_optimization_passes): Likewise.
>>> 	* profile.cc (find_conditions): New declaration.
>>> 	(cov_length): Likewise.
>>> 	(cov_blocks): Likewise.
>>> 	(cov_masks): Likewise.
>>> 	(cov_free): Likewise.
>>> 	(instrument_decisions): New.
>>> 	(read_thunk_profile): Control output to file.
>>> 	(branch_prob): Call find_conditions, instrument_decisions.
>>> 	(init_branch_prob): Add total_num_conds.
>>> 	(end_branch_prob): Likewise.
>>> 	* tree-profile.cc (struct conds_ctx): New.
>>> 	(CONDITIONS_MAX_TERMS): New.
>>> 	(EDGE_CONDITION): New.
>>> 	(cmp_index_map): New.
>>> 	(index_of): New.
>>> 	(block_conditional_p): New.
>>> 	(edge_conditional_p): New.
>>> 	(single): New.
>>> 	(single_edge): New.
>>> 	(contract_edge): New.
>>> 	(contract_edge_up): New.
>>> 	(merge_split_outcome): New.
>>> 	(ancestors_of): New.
>>> 	(struct outcomes): New.
>>> 	(conditional_succs): New.
>>> 	(condition_index): New.
>>> 	(masking_vectors): New.
>>> 	(cond_reachable_from): New.
>>> 	(neighborhood): New.
>>> 	(isolate_expression): New.
>>> 	(emit_bitwise_op): New.
>>> 	(make_index_map_visit): New.
>>> 	(make_index_map): New.
>>> 	(collect_conditions): New.
>>> 	(yes): New.
>>> 	(struct condcov): New.
>>> 	(cov_length): New.
>>> 	(cov_blocks): New.
>>> 	(cov_masks): New.
>>> 	(cov_free): New.
>>> 	(find_conditions): New.
>>> 	(instrument_decisions): New.
>>> 	(tree_profiling): Check profile_condition_flag.
>>> 	(pass_ipa_tree_profile::gate): Likewise.
>>>
>>> libgcc/ChangeLog:
>>>
>>> 	* libgcov-merge.c (__gcov_merge_ior): New dummy function.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> 	* lib/gcov.exp: Add condition coverage test function.
>>> 	* g++.dg/gcov/gcov-18.C: New test.
>>> 	* gcc.misc-tests/gcov-19.c: New test.
>>> 	* gcc.misc-tests/gcov-20.c: New test.
>>> 	* gcc.misc-tests/gcov-21.c: New test.
>>> ---
>>>  gcc/builtins.cc                        |    2 +-
>>>  gcc/collect2.cc                        |    7 +-
>>>  gcc/common.opt                         |    8 +
>>>  gcc/doc/gcov.texi                      |   36 +
>>>  gcc/doc/invoke.texi                    |   19 +
>>>  gcc/gcc.cc                             |    4 +-
>>>  gcc/gcov-counter.def                   |    3 +
>>>  gcc/gcov-dump.cc                       |   24 +
>>>  gcc/gcov-io.h                          |    3 +
>>>  gcc/gcov.cc                            |  200 +++-
>>>  gcc/ipa-inline.cc                      |    2 +-
>>>  gcc/ipa-split.cc                       |    3 +-
>>>  gcc/passes.cc                          |    3 +-
>>>  gcc/profile.cc                         |   84 +-
>>>  gcc/testsuite/g++.dg/gcov/gcov-18.C    |  234 +++++
>>>  gcc/testsuite/gcc.misc-tests/gcov-19.c | 1250 ++++++++++++++++++++++++
>>>  gcc/testsuite/gcc.misc-tests/gcov-20.c |   22 +
>>>  gcc/testsuite/gcc.misc-tests/gcov-21.c |   16 +
>>>  gcc/testsuite/lib/gcov.exp             |  191 +++-
>>>  gcc/tree-profile.cc                    | 1050 +++++++++++++++++++-
>>>  libgcc/libgcov-merge.c                 |    5 +
>>>  21 files changed, 3138 insertions(+), 28 deletions(-)
>>>  create mode 100644 gcc/testsuite/g++.dg/gcov/gcov-18.C
>>>  create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-19.c
>>>  create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-20.c
>>>  create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-21.c
>>>
>>> diff --git a/gcc/builtins.cc b/gcc/builtins.cc
>>> index 5f319b28030..972ae7e2040 100644
>>> --- a/gcc/builtins.cc
>>> +++ b/gcc/builtins.cc
>>> @@ -5884,7 +5884,7 @@ expand_builtin_fork_or_exec (tree fn, tree exp, rtx target, int ignore)
>>>    tree call;
>>>  
>>>    /* If we are not profiling, just call the function.  */
>>> -  if (!profile_arc_flag)
>>> +  if (!profile_arc_flag && !profile_condition_flag)
>>>      return NULL_RTX;
>>>  
>>>    /* Otherwise call the wrapper.  This should be equivalent for the rest of
>>> diff --git a/gcc/collect2.cc b/gcc/collect2.cc
>>> index d81c7f28f16..0cd8bf4a3a3 100644
>>> --- a/gcc/collect2.cc
>>> +++ b/gcc/collect2.cc
>>> @@ -1032,9 +1032,9 @@ main (int argc, char **argv)
>>>        lto_mode = LTO_MODE_LTO;
>>>    }
>>>  
>>> -  /* -fno-profile-arcs -fno-test-coverage -fno-branch-probabilities
>>> -     -fno-exceptions -w -fno-whole-program */
>>> -  num_c_args += 6;
>>> +  /* -fno-profile-arcs -fno-profile-conditions -fno-test-coverage
>>> +     -fno-branch-probabilities -fno-exceptions -w -fno-whole-program */
>>> +  num_c_args += 7;
>>>  
>>>    c_argv = XCNEWVEC (char *, num_c_args);
>>>    c_ptr = CONST_CAST2 (const char **, char **, c_argv);
>>> @@ -1230,6 +1230,7 @@ main (int argc, char **argv)
>>>      }
>>>    obstack_free (&temporary_obstack, temporary_firstobj);
>>>    *c_ptr++ = "-fno-profile-arcs";
>>> +  *c_ptr++ = "-fno-profile-conditions";
>>>    *c_ptr++ = "-fno-test-coverage";
>>>    *c_ptr++ = "-fno-branch-probabilities";
>>>    *c_ptr++ = "-fno-exceptions";
>>> diff --git a/gcc/common.opt b/gcc/common.opt
>>> index bce3e514f65..5d0682e283a 100644
>>> --- a/gcc/common.opt
>>> +++ b/gcc/common.opt
>>> @@ -859,6 +859,10 @@ Wcoverage-invalid-line-number
>>>  Common Var(warn_coverage_invalid_linenum) Init(1) Warning
>>>  Warn in case a function ends earlier than it begins due to an invalid linenum macros.
>>>  
>>> +Wcoverage-too-many-conditions
>>> +Common Var(warn_too_many_conditions) Init(1) Warning
>>> +Warn when a conditional has too many terms and coverage gives up.
>>> +
>>>  Wmissing-profile
>>>  Common Var(warn_missing_profile) Init(1) Warning
>>>  Warn in case profiles in -fprofile-use do not exist.
>>> @@ -2318,6 +2322,10 @@ fprofile-arcs
>>>  Common Var(profile_arc_flag)
>>>  Insert arc-based program profiling code.
>>>  
>>> +fprofile-conditions
>>> +Common Var(profile_condition_flag)
>>> +Insert condition coverage profiling code.
>>> +
>>>  fprofile-dir=
>>>  Common Joined RejectNegative Var(profile_data_prefix)
>>>  Set the top-level directory for storing the profile data.
>>> diff --git a/gcc/doc/gcov.texi b/gcc/doc/gcov.texi
>>> index a1f7d26e610..7f2c0d00d94 100644
>>> --- a/gcc/doc/gcov.texi
>>> +++ b/gcc/doc/gcov.texi
>>> @@ -124,6 +124,7 @@ gcov [@option{-v}|@option{--version}] [@option{-h}|@option{--help}]
>>>       [@option{-a}|@option{--all-blocks}]
>>>       [@option{-b}|@option{--branch-probabilities}]
>>>       [@option{-c}|@option{--branch-counts}]
>>> +     [@option{-g}|@option{--conditions}]
>>>       [@option{-d}|@option{--display-progress}]
>>>       [@option{-f}|@option{--function-summaries}]
>>>       [@option{-j}|@option{--json-format}]
>>> @@ -169,6 +170,13 @@ be shown, unless the @option{-u} option is given.
>>>  Write branch frequencies as the number of branches taken, rather than
>>>  the percentage of branches taken.
>>>  
>>> +@item -g
>>> +@itemx --conditions
>>> +Write condition coverage to the output file, and write condition summary info
>>> +to the standard output.  This option allows you to see if the conditions in
>>> +your program at least once had an independent effect on the outcome of the
>>> +boolean expression (modified condition/decision coverage).
>>> +
>>>  @item -d
>>>  @itemx --display-progress
>>>  Display the progress on the standard output.
>>> @@ -293,6 +301,7 @@ Each @var{line} has the following form:
>>>  @{
>>>    "branches": ["$branch"],
>>>    "count": 2,
>>> +  "conditions": ["$condition"],
>>>    "line_number": 15,
>>>    "unexecuted_block": false,
>>>    "function_name": "foo",
>>> @@ -341,6 +350,33 @@ Fields of the @var{branch} element have following semantics:
>>>  @var{throw}: true when the branch is an exceptional branch
>>>  @end itemize
>>>  
>>> +Each @var{condition} element have the following semantics:
>>> +
>>> +@smallexample
>>> +@{
>>> +  "count": 4,
>>> +  "covered": 2,
>>> +  "not_covered_false": [],
>>> +  "not_covered_true": [0, 1],
>>> +@}
>>> +@end smallexample
>>> +
>>> +Fields of the @var{condition} element have following semantics:
>>> +
>>> +@itemize @bullet
>>> +@item
>>> +@var{count}: number of conditions in this expression
>>> +
>>> +@item
>>> +@var{covered}: number of covered conditions in this expression
>>> +
>>> +@item
>>> +@var{not_covered_true}: terms, by index, not seen as true in this expression
>>> +
>>> +@item
>>> +@var{not_covered_false}: terms, by index, not seen as false in this expression
>>> +@end itemize
>>> +
>>>  @item -H
>>>  @itemx --human-readable
>>>  Write counts in human readable format (like 24.6k).
>>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>>> index a9ecc4426a4..62d48df369d 100644
>>> --- a/gcc/doc/invoke.texi
>>> +++ b/gcc/doc/invoke.texi
>>> @@ -614,6 +614,7 @@ Objective-C and Objective-C++ Dialects}.
>>>  @item Program Instrumentation Options
>>>  @xref{Instrumentation Options,,Program Instrumentation Options}.
>>>  @gccoptlist{-p  -pg  -fprofile-arcs  --coverage  -ftest-coverage @gol
>>> +-fprofile-conditions @gol
>>>  -fprofile-abs-path @gol
>>>  -fprofile-dir=@var{path}  -fprofile-generate  -fprofile-generate=@var{path} @gol
>>>  -fprofile-info-section  -fprofile-info-section=@var{name} @gol
>>> @@ -6140,6 +6141,13 @@ error.  @option{-Wno-coverage-invalid-line-number} can be used to disable the
>>>  warning or @option{-Wno-error=coverage-invalid-line-number} can be used to
>>>  disable the error.
>>>  
>>> +@item -Wno-coverage-too-many-conditions
>>> +@opindex Wno-coverage-too-many-conditions
>>> +@opindex Wcoverage-too-many-conditions
>>> +Warn in case a condition have too many terms and GCC gives up coverage.
>>> +Coverage is given up when there are more terms in the conditional than there
>>> +are bits in a @code{gcov_type_unsigned}.  This warning is enabled by default.
>>> +
>>>  @item -Wno-cpp @r{(C, Objective-C, C++, Objective-C++ and Fortran only)}
>>>  @opindex Wno-cpp
>>>  @opindex Wcpp
>>> @@ -15839,6 +15847,13 @@ E.g. @code{gcc a.c b.c -o binary} would generate @file{binary-a.gcda} and
>>>  
>>>  @xref{Cross-profiling}.
>>>  
>>> +@item -fprofile-conditions
>>> +@opindex fprofile-conditions
>>> +Add code so that program conditions are instrumented.  During execution the
>>> +program records what terms in a conditional contributes to a decision.  The
>>> +data may be used to verify that all terms in a booleans are tested and have an
>>> +effect on the outcome of a condition.
>>> +
>>>  @cindex @command{gcov}
>>>  @item --coverage
>>>  @opindex coverage
>>> @@ -15899,6 +15914,10 @@ executed.  When an arc is the only exit or only entrance to a block, the
>>>  instrumentation code can be added to the block; otherwise, a new basic
>>>  block must be created to hold the instrumentation code.
>>>  
>>> +With @option{-fprofile-conditions}, for each conditional in your program GCC
>>> +creates a bitset and records the boolean values that have an independent effect
>>> +on the outcome of that expression.
>>> +
>>>  @need 2000
>>>  @item -ftest-coverage
>>>  @opindex ftest-coverage
>>> diff --git a/gcc/gcc.cc b/gcc/gcc.cc
>>> index afb23cd07b0..601e48377de 100644
>>> --- a/gcc/gcc.cc
>>> +++ b/gcc/gcc.cc
>>> @@ -1145,7 +1145,7 @@ proper position among the other output files.  */
>>>  	%:include(libgomp.spec)%(link_gomp)}\
>>>      %{fgnu-tm:%:include(libitm.spec)%(link_itm)}\
>>>      %(mflib) " STACK_SPLIT_SPEC "\
>>> -    %{fprofile-arcs|fprofile-generate*|coverage:-lgcov} " SANITIZER_SPEC " \
>>> +    %{fprofile-arcs|fprofile-conditions|fprofile-generate*|coverage:-lgcov} " SANITIZER_SPEC " \
>>>      %{!nostdlib:%{!r:%{!nodefaultlibs:%(link_ssp) %(link_gcc_c_sequence)}}}\
>>>      %{!nostdlib:%{!r:%{!nostartfiles:%E}}} %{T*}  \n%(post_link) }}}}}}"
>>>  #endif
>>> @@ -1262,7 +1262,7 @@ static const char *cc1_options =
>>>   %{!fsyntax-only:%{S:%W{o*}%{!o*:-o %w%b.s}}}\
>>>   %{fsyntax-only:-o %j} %{-param*}\
>>>   %{coverage:-fprofile-arcs -ftest-coverage}\
>>> - %{fprofile-arcs|fprofile-generate*|coverage:\
>>> + %{fprofile-arcs|fprofile-conditions|fprofile-generate*|coverage:\
>>>     %{!fprofile-update=single:\
>>>       %{pthread:-fprofile-update=prefer-atomic}}}";
>>>  
>>> diff --git a/gcc/gcov-counter.def b/gcc/gcov-counter.def
>>> index 6d2182bd3db..96563a59a45 100644
>>> --- a/gcc/gcov-counter.def
>>> +++ b/gcc/gcov-counter.def
>>> @@ -49,3 +49,6 @@ DEF_GCOV_COUNTER(GCOV_COUNTER_IOR, "ior", _ior)
>>>  
>>>  /* Time profile collecting first run of a function */
>>>  DEF_GCOV_COUNTER(GCOV_TIME_PROFILER, "time_profiler", _time_profile)
>>> +
>>> +/* Conditions.  The counter is interpreted as a bit-set.  */
>>> +DEF_GCOV_COUNTER(GCOV_COUNTER_CONDS, "conditions", _ior)
>>> diff --git a/gcc/gcov-dump.cc b/gcc/gcov-dump.cc
>>> index 03023bfb226..6dc1df6e3e1 100644
>>> --- a/gcc/gcov-dump.cc
>>> +++ b/gcc/gcov-dump.cc
>>> @@ -38,6 +38,7 @@ static void print_version (void);
>>>  static void tag_function (const char *, unsigned, int, unsigned);
>>>  static void tag_blocks (const char *, unsigned, int, unsigned);
>>>  static void tag_arcs (const char *, unsigned, int, unsigned);
>>> +static void tag_conditions (const char *, unsigned, int, unsigned);
>>>  static void tag_lines (const char *, unsigned, int, unsigned);
>>>  static void tag_counters (const char *, unsigned, int, unsigned);
>>>  static void tag_summary (const char *, unsigned, int, unsigned);
>>> @@ -77,6 +78,7 @@ static const tag_format_t tag_table[] =
>>>    {GCOV_TAG_FUNCTION, "FUNCTION", tag_function},
>>>    {GCOV_TAG_BLOCKS, "BLOCKS", tag_blocks},
>>>    {GCOV_TAG_ARCS, "ARCS", tag_arcs},
>>> +  {GCOV_TAG_CONDS, "CONDITIONS", tag_conditions},
>>>    {GCOV_TAG_LINES, "LINES", tag_lines},
>>>    {GCOV_TAG_OBJECT_SUMMARY, "OBJECT_SUMMARY", tag_summary},
>>>    {0, NULL, NULL}
>>> @@ -392,6 +394,28 @@ tag_arcs (const char *filename ATTRIBUTE_UNUSED,
>>>      }
>>>  }
>>>  
>>> +static void
>>> +tag_conditions (const char *filename ATTRIBUTE_UNUSED,
>>> +		unsigned tag ATTRIBUTE_UNUSED, int length ATTRIBUTE_UNUSED,
>>> +		unsigned depth)
>>> +{
>>> +  unsigned n_conditions = GCOV_TAG_CONDS_NUM (length);
>>> +
>>> +  printf (" %u conditionals", n_conditions);
>>> +  if (flag_dump_contents)
>>> +    {
>>> +      for (unsigned ix = 0; ix != n_conditions; ix++)
>>> +	{
>>> +	  const unsigned blockno = gcov_read_unsigned ();
>>> +	  const unsigned nterms = gcov_read_unsigned ();
>>> +
>>> +	  printf ("\n");
>>> +	  print_prefix (filename, depth, gcov_position ());
>>> +	  printf (VALUE_PADDING_PREFIX "block %u:", blockno);
>>> +	  printf (" %u", nterms);
>>> +	}
>>> +    }
>>> +}
>>>  static void
>>>  tag_lines (const char *filename ATTRIBUTE_UNUSED,
>>>  	   unsigned tag ATTRIBUTE_UNUSED, int length ATTRIBUTE_UNUSED,
>>> diff --git a/gcc/gcov-io.h b/gcc/gcov-io.h
>>> index e91cd736556..a9b52cc6abc 100644
>>> --- a/gcc/gcov-io.h
>>> +++ b/gcc/gcov-io.h
>>> @@ -261,6 +261,9 @@ typedef uint64_t gcov_type_unsigned;
>>>  #define GCOV_TAG_ARCS		 ((gcov_unsigned_t)0x01430000)
>>>  #define GCOV_TAG_ARCS_LENGTH(NUM)  (1 + (NUM) * 2 * GCOV_WORD_SIZE)
>>>  #define GCOV_TAG_ARCS_NUM(LENGTH)  (((LENGTH / GCOV_WORD_SIZE) - 1) / 2)
>>> +#define GCOV_TAG_CONDS             ((gcov_unsigned_t)0x01470000)
>>> +#define GCOV_TAG_CONDS_LENGTH(NUM) ((NUM) * 2 * GCOV_WORD_SIZE)
>>> +#define GCOV_TAG_CONDS_NUM(LENGTH) (((LENGTH) / GCOV_WORD_SIZE) / 2)
>>>  #define GCOV_TAG_LINES		 ((gcov_unsigned_t)0x01450000)
>>>  #define GCOV_TAG_COUNTER_BASE 	 ((gcov_unsigned_t)0x01a10000)
>>>  #define GCOV_TAG_COUNTER_LENGTH(NUM) ((NUM) * 2 * GCOV_WORD_SIZE)
>>> diff --git a/gcc/gcov.cc b/gcc/gcov.cc
>>> index 9cf1071166f..bc2932e7890 100644
>>> --- a/gcc/gcov.cc
>>> +++ b/gcc/gcov.cc
>>> @@ -79,6 +79,7 @@ using namespace std;
>>>  class function_info;
>>>  class block_info;
>>>  class source_info;
>>> +class condition_info;
>>>  
>>>  /* Describes an arc between two basic blocks.  */
>>>  
>>> @@ -132,6 +133,28 @@ public:
>>>    vector<unsigned> lines;
>>>  };
>>>  
>>> +class condition_info
>>> +{
>>> +public:
>>> +  condition_info ();
>>> +
>>> +  int popcount () const;
>>> +
>>> +  gcov_type_unsigned truev;
>>> +  gcov_type_unsigned falsev;
>>> +
>>> +  unsigned n_terms;
>>> +};
>>> +
>>> +condition_info::condition_info (): truev (0), falsev (0), n_terms (0)
>>> +{
>>> +}
>>> +
>>> +int condition_info::popcount () const
>>> +{
>>> +    return __builtin_popcountll (truev) + __builtin_popcountll (falsev);
>>> +}
>>> +
>>>  /* Describes a basic block. Contains lists of arcs to successor and
>>>     predecessor blocks.  */
>>>  
>>> @@ -165,6 +188,8 @@ public:
>>>    /* Block is a landing pad for longjmp or throw.  */
>>>    unsigned is_nonlocal_return : 1;
>>>  
>>> +  condition_info conditions;
>>> +
>>>    vector<block_location_info> locations;
>>>  
>>>    struct
>>> @@ -275,6 +300,8 @@ public:
>>>    vector<block_info> blocks;
>>>    unsigned blocks_executed;
>>>  
>>> +  vector<condition_info*> conditions;
>>> +
>>>    /* Raw arc coverage counts.  */
>>>    vector<gcov_type> counts;
>>>  
>>> @@ -351,6 +378,9 @@ struct coverage_info
>>>    int branches_executed;
>>>    int branches_taken;
>>>  
>>> +  int conditions;
>>> +  int conditions_covered;
>>> +
>>>    int calls;
>>>    int calls_executed;
>>>  
>>> @@ -550,6 +580,10 @@ static int multiple_files = 0;
>>>  
>>>  static int flag_branches = 0;
>>>  
>>> +/* Output conditions (modified condition/decision coverage) */
>>> +
>>> +static int flag_conditions = 0;
>>> +
>>>  /* Show unconditional branches too.  */
>>>  static int flag_unconditional = 0;
>>>  
>>> @@ -656,6 +690,7 @@ static int read_count_file (void);
>>>  static void solve_flow_graph (function_info *);
>>>  static void find_exception_blocks (function_info *);
>>>  static void add_branch_counts (coverage_info *, const arc_info *);
>>> +static void add_condition_counts (coverage_info *, const block_info *);
>>>  static void add_line_counts (coverage_info *, function_info *);
>>>  static void executed_summary (unsigned, unsigned);
>>>  static void function_summary (const coverage_info *);
>>> @@ -664,6 +699,7 @@ static const char *format_gcov (gcov_type, gcov_type, int);
>>>  static void accumulate_line_counts (source_info *);
>>>  static void output_gcov_file (const char *, source_info *);
>>>  static int output_branch_count (FILE *, int, const arc_info *);
>>> +static void output_conditions (FILE *, const block_info *);
>>>  static void output_lines (FILE *, const source_info *);
>>>  static string make_gcov_file_name (const char *, const char *);
>>>  static char *mangle_name (const char *);
>>> @@ -928,6 +964,7 @@ print_usage (int error_p)
>>>    fnotice (file, "  -b, --branch-probabilities      Include branch probabilities in output\n");
>>>    fnotice (file, "  -c, --branch-counts             Output counts of branches taken\n\
>>>                                      rather than percentages\n");
>>> +  fnotice (file, "  -g, --conditions                Include condition/decision coverage in output\n");
>>>    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");
>>> @@ -980,6 +1017,7 @@ static const struct option options[] =
>>>    { "all-blocks",           no_argument,       NULL, 'a' },
>>>    { "branch-probabilities", no_argument,       NULL, 'b' },
>>>    { "branch-counts",        no_argument,       NULL, 'c' },
>>> +  { "conditions",           no_argument,       NULL, 'g' },
>>>    { "json-format",	    no_argument,       NULL, 'j' },
>>>    { "human-readable",	    no_argument,       NULL, 'H' },
>>>    { "no-output",            no_argument,       NULL, 'n' },
>>> @@ -1008,7 +1046,7 @@ process_args (int argc, char **argv)
>>>  {
>>>    int opt;
>>>  
>>> -  const char *opts = "abcdDfhHijklmno:pqrs:tuvwx";
>>> +  const char *opts = "abcdDfghHijklmno:pqrs:tuvwx";
>>>    while ((opt = getopt_long (argc, argv, opts, options, NULL)) != -1)
>>>      {
>>>        switch (opt)
>>> @@ -1025,6 +1063,9 @@ process_args (int argc, char **argv)
>>>  	case 'f':
>>>  	  flag_function_summary = 1;
>>>  	  break;
>>> +	case 'g':
>>> +	  flag_conditions = 1;
>>> +	  break;
>>>  	case 'h':
>>>  	  print_usage (false);
>>>  	  /* print_usage will exit.  */
>>> @@ -1132,6 +1173,45 @@ output_intermediate_json_line (json::array *object,
>>>  	  }
>>>        }
>>>  
>>> +  json::array *conditions = new json::array ();
>>> +  lineo->set ("conditions", conditions);
>>> +  if (flag_conditions)
>>> +  {
>>> +    vector<block_info *>::const_iterator it;
>>> +    for (it = line->blocks.begin (); it != line->blocks.end (); it++)
>>> +      {
>>> +	const condition_info& info = (*it)->conditions;
>>> +	if (info.n_terms == 0)
>>> +	    continue;
>>> +
>>> +	const int count = 2 * info.n_terms;
>>> +	const int covered = info.popcount ();
>>> +
>>> +	json::object *cond = new json::object ();
>>> +	cond->set ("count", new json::integer_number (count));
>>> +	cond->set ("covered", new json::integer_number (covered));
>>> +
>>> +	json::array *mtrue = new json::array ();
>>> +	json::array *mfalse = new json::array ();
>>> +	cond->set ("not_covered_true", mtrue);
>>> +	cond->set ("not_covered_false", mfalse);
>>> +
>>> +	if (count != covered)
>>> +	  {
>>> +	    for (unsigned i = 0; i < info.n_terms; i++)
>>> +	      {
>>> +		gcov_type_unsigned index = 1;
>>> +		index <<= i;
>>> +		if (!(index & info.truev))
>>> +		    mtrue->append (new json::integer_number (i));
>>> +		if (!(index & info.falsev))
>>> +		    mfalse->append (new json::integer_number (i));
>>> +	      }
>>> +	  }
>>> +	conditions->append (cond);
>>> +      }
>>> +  }
>>> +
>>>    object->append (lineo);
>>>  }
>>>  
>>> @@ -1956,6 +2036,28 @@ read_graph_file (void)
>>>  		  }
>>>  	    }
>>>  	}
>>> +      else if (fn && tag == GCOV_TAG_CONDS)
>>> +	{
>>> +	  unsigned num_dests = GCOV_TAG_CONDS_NUM (length);
>>> +
>>> +	  if (!fn->conditions.empty ())
>>> +	    fnotice (stderr, "%s:already seen conditions for '%s'\n",
>>> +		     bbg_file_name, fn->get_name ());
>>> +	  else
>>> +	    fn->conditions.resize (num_dests);
>>> +
>>> +	  for (unsigned i = 0; i < num_dests; ++i)
>>> +	    {
>>> +	      unsigned idx = gcov_read_unsigned ();
>>> +
>>> +	      if (idx >= fn->blocks.size ())
>>> +		goto corrupt;
>>> +
>>> +	      condition_info *info = &fn->blocks[idx].conditions;
>>> +	      info->n_terms = gcov_read_unsigned ();
>>> +	      fn->conditions[i] = info;
>>> +	    }
>>> +	}
>>>        else if (fn && tag == GCOV_TAG_LINES)
>>>  	{
>>>  	  unsigned blockno = gcov_read_unsigned ();
>>> @@ -2086,11 +2188,26 @@ read_count_file (void)
>>>  	      goto cleanup;
>>>  	    }
>>>  	}
>>> -      else if (tag == GCOV_TAG_FOR_COUNTER (GCOV_COUNTER_ARCS) && fn)
>>> +      else if (tag == GCOV_TAG_FOR_COUNTER (GCOV_COUNTER_CONDS) && fn)
>>>  	{
>>> +	  length = abs (read_length);
>>> +	  if (length != GCOV_TAG_COUNTER_LENGTH (2 * fn->conditions.size ()))
>>> +	      goto mismatch;
>>> +
>>> +	  if (read_length > 0)
>>> +	    {
>>> +	      for (ix = 0; ix != fn->conditions.size (); ix++)
>>> +		{
>>> +		  fn->conditions[ix]->truev  |= gcov_read_counter ();
>>> +		  fn->conditions[ix]->falsev |= gcov_read_counter ();
>>> +		}
>>> +	    }
>>> +	}
>>> +      else if (tag == GCOV_TAG_FOR_COUNTER (GCOV_COUNTER_ARCS) && fn)
>>> +      {
>>>  	  length = abs (read_length);
>>>  	  if (length != GCOV_TAG_COUNTER_LENGTH (fn->counts.size ()))
>>> -	    goto mismatch;
>>> +	      goto mismatch;
>>>  
>>>  	  if (read_length > 0)
>>>  	    for (ix = 0; ix != fn->counts.size (); ix++)
>>> @@ -2430,6 +2547,13 @@ add_branch_counts (coverage_info *coverage, const arc_info *arc)
>>>      }
>>>  }
>>>  
>>> +static void
>>> +add_condition_counts (coverage_info *coverage, const block_info *block)
>>> +{
>>> +  coverage->conditions += 2 * block->conditions.n_terms;
>>> +  coverage->conditions_covered += block->conditions.popcount ();
>>> +}
>>> +
>>>  /* Format COUNT, if flag_human_readable_numbers is set, return it human
>>>     readable format.  */
>>>  
>>> @@ -2533,6 +2657,18 @@ file_summary (const coverage_info *coverage)
>>>  		 coverage->calls);
>>>        else
>>>  	fnotice (stdout, "No calls\n");
>>> +
>>> +    }
>>> +
>>> +  if (flag_conditions)
>>> +    {
>>> +      if (coverage->conditions)
>>> +	fnotice (stdout, "Decisions covered:%s of %d\n",
>>> +		 format_gcov (coverage->conditions_covered,
>>> +			      coverage->conditions, 2),
>>> +		 coverage->conditions);
>>> +      else
>>> +	fnotice (stdout, "No decisions\n");
>>>      }
>>>  }
>>>  
>>> @@ -2767,6 +2903,12 @@ static void accumulate_line_info (line_info *line, source_info *src,
>>>  	 it != line->branches.end (); it++)
>>>        add_branch_counts (&src->coverage, *it);
>>>  
>>> +  if (add_coverage)
>>> +    for (vector<block_info *>::iterator it = line->blocks.begin ();
>>> +	 it != line->blocks.end (); it++)
>>> +      add_condition_counts (&src->coverage, *it);
>>> +
>>> +
>>>    if (!line->blocks.empty ())
>>>      {
>>>        /* The user expects the line count to be the number of times
>>> @@ -2868,6 +3010,33 @@ accumulate_line_counts (source_info *src)
>>>        }
>>>  }
>>>  
>>> +static void
>>> +output_conditions (FILE *gcov_file, const block_info *binfo)
>>> +{
>>> +    const condition_info& info = binfo->conditions;
>>> +    if (info.n_terms == 0)
>>> +	return;
>>> +
>>> +    const int expected = 2 * info.n_terms;
>>> +    const int got = info.popcount ();
>>> +
>>> +    fnotice (gcov_file, "condition outcomes covered %d/%d\n", got, expected);
>>> +    if (expected == got)
>>> +	return;
>>> +
>>> +    for (unsigned i = 0; i < info.n_terms; i++)
>>> +    {
>>> +	gcov_type_unsigned index = 1;
>>> +	index <<= i;
>>> +	if ((index & info.truev & info.falsev))
>>> +	    continue;
>>> +
>>> +	const char *t = (index & info.truev) ? "" : "true";
>>> +	const char *f = (index & info.falsev) ? "" : " false";
>>> +	fnotice (gcov_file, "condition %2u not covered (%s%s)\n", i, t, f + !t[0]);
>>> +    }
>>> +}
>>> +
>>>  /* Output information about ARC number IX.  Returns nonzero if
>>>     anything is output.  */
>>>  
>>> @@ -3078,16 +3247,29 @@ output_line_details (FILE *f, const line_info *line, unsigned line_num)
>>>  	  if (flag_branches)
>>>  	    for (arc = (*it)->succ; arc; arc = arc->succ_next)
>>>  	      jx += output_branch_count (f, jx, arc);
>>> +
>>> +	  if (flag_conditions)
>>> +	      output_conditions (f, *it);
>>>  	}
>>>      }
>>> -  else if (flag_branches)
>>> +  else
>>>      {
>>> -      int ix;
>>> +      if (flag_branches)
>>> +	{
>>> +	  int ix;
>>> +
>>> +	  ix = 0;
>>> +	  for (vector<arc_info *>::const_iterator it = line->branches.begin ();
>>> +		  it != line->branches.end (); it++)
>>> +	      ix += output_branch_count (f, ix, (*it));
>>> +	}
>>>  
>>> -      ix = 0;
>>> -      for (vector<arc_info *>::const_iterator it = line->branches.begin ();
>>> -	   it != line->branches.end (); it++)
>>> -	ix += output_branch_count (f, ix, (*it));
>>> +      if (flag_conditions)
>>> +	{
>>> +	  for (vector<block_info *>::const_iterator it = line->blocks.begin ();
>>> +	       it != line->blocks.end (); it++)
>>> +	      output_conditions (f, *it);
>>> +	}
>>>      }
>>>  }
>>>  
>>> diff --git a/gcc/ipa-inline.cc b/gcc/ipa-inline.cc
>>> index 14969198cde..3e37305843e 100644
>>> --- a/gcc/ipa-inline.cc
>>> +++ b/gcc/ipa-inline.cc
>>> @@ -646,7 +646,7 @@ can_early_inline_edge_p (struct cgraph_edge *e)
>>>  			 "  edge not inlinable: not in SSA form\n");
>>>        return false;
>>>      }
>>> -  else if (profile_arc_flag
>>> +  else if ((profile_arc_flag || profile_condition_flag)
>>>  	   && ((lookup_attribute ("no_profile_instrument_function",
>>>  				 DECL_ATTRIBUTES (caller->decl)) == NULL_TREE)
>>>  	       != (lookup_attribute ("no_profile_instrument_function",
>>> diff --git a/gcc/ipa-split.cc b/gcc/ipa-split.cc
>>> index 16734617d03..07d2b17ab12 100644
>>> --- a/gcc/ipa-split.cc
>>> +++ b/gcc/ipa-split.cc
>>> @@ -1929,7 +1929,8 @@ pass_split_functions::gate (function *)
>>>    /* When doing profile feedback, we want to execute the pass after profiling
>>>       is read.  So disable one in early optimization.  */
>>>    return (flag_partial_inlining
>>> -	  && !profile_arc_flag && !flag_branch_probabilities);
>>> +      && !profile_arc_flag && !flag_branch_probabilities
>>> +      && !profile_condition_flag);
>>>  }
>>>  
>>>  } // anon namespace
>>> diff --git a/gcc/passes.cc b/gcc/passes.cc
>>> index 78a07f8691a..3457ad1c5b3 100644
>>> --- a/gcc/passes.cc
>>> +++ b/gcc/passes.cc
>>> @@ -352,7 +352,8 @@ finish_optimization_passes (void)
>>>    gcc::dump_manager *dumps = m_ctxt->get_dumps ();
>>>  
>>>    timevar_push (TV_DUMP);
>>> -  if (profile_arc_flag || flag_test_coverage || flag_branch_probabilities)
>>> +  if (profile_arc_flag || profile_condition_flag || flag_test_coverage
>>> +      || flag_branch_probabilities)
>>>      {
>>>        dumps->dump_start (pass_profile_1->static_pass_number, NULL);
>>>        end_branch_prob ();
>>> diff --git a/gcc/profile.cc b/gcc/profile.cc
>>> index 96121d60711..f7f6d1f7197 100644
>>> --- a/gcc/profile.cc
>>> +++ b/gcc/profile.cc
>>> @@ -66,9 +66,19 @@ along with GCC; see the file COPYING3.  If not see
>>>  #include "cfgloop.h"
>>>  #include "sreal.h"
>>>  #include "file-prefix-map.h"
>>> +#include "stringpool.h"
>>>  
>>>  #include "profile.h"
>>>  
>>> +struct condcov;
>>> +struct condcov *find_conditions (struct function*);
>>> +unsigned cov_length (const struct condcov*);
>>> +array_slice<basic_block> cov_blocks (struct condcov*, unsigned);
>>> +array_slice<gcov_type_unsigned > cov_masks (struct condcov*, unsigned);
>>> +void cov_free (struct condcov*);
>>> +int instrument_decisions (array_slice<basic_block>, unsigned, tree*,
>>> +			  gcov_type_unsigned*);
>>> +
>>>  /* Map from BBs/edges to gcov counters.  */
>>>  vec<gcov_type> bb_gcov_counts;
>>>  hash_map<edge,gcov_type> *edge_gcov_counts;
>>> @@ -100,6 +110,7 @@ static int total_num_passes;
>>>  static int total_num_times_called;
>>>  static int total_hist_br_prob[20];
>>>  static int total_num_branches;
>>> +static int total_num_conds;
>>>  
>>>  /* Forward declarations.  */
>>>  static void find_spanning_tree (struct edge_list *);
>>> @@ -1155,6 +1166,12 @@ read_thunk_profile (struct cgraph_node *node)
>>>     the flow graph that are needed to reconstruct the dynamic behavior of the
>>>     flow graph.  This data is written to the gcno file for gcov.
>>>  
>>> +   When FLAG_PROFILE_CONDITIONS is nonzero, this functions instruments the
>>> +   edges in the control flow graph to track what conditions are evaluated to in
>>> +   order to determine what conditions are covered and have an independent
>>> +   effect on the outcome (modified condition/decision coverage).  This data is
>>> +   written to the gcno file for gcov.
>>> +
>>>     When FLAG_BRANCH_PROBABILITIES is nonzero, this function reads auxiliary
>>>     information from the gcda file containing edge count information from
>>>     previous executions of the function being compiled.  In this case, the
>>> @@ -1173,6 +1190,7 @@ branch_prob (bool thunk)
>>>    struct edge_list *el;
>>>    histogram_values values = histogram_values ();
>>>    unsigned cfg_checksum, lineno_checksum;
>>> +  bool output_to_file;
>>>  
>>>    total_num_times_called++;
>>>  
>>> @@ -1397,10 +1415,18 @@ branch_prob (bool thunk)
>>>  
>>>    /* Write the data from which gcov can reconstruct the basic block
>>>       graph and function line numbers (the gcno file).  */
>>> +  output_to_file = false;
>>>    if (coverage_begin_function (lineno_checksum, cfg_checksum))
>>>      {
>>>        gcov_position_t offset;
>>>  
>>> +      /* The condition coverage needs a deeper analysis to identify expressions
>>> +       * of conditions, which means it is not yet ready to write to the gcno
>>> +       * file.  It will write its entries later, but needs to know if it do it
>>> +       * in the first place, which is controlled by the return value of
>>> +       * coverage_begin_function. */
>>> +      output_to_file = true;
>>> +
>>>        /* Basic block flags */
>>>        offset = gcov_write_tag (GCOV_TAG_BLOCKS);
>>>        gcov_write_unsigned (n_basic_blocks_for_fn (cfun));
>>> @@ -1512,29 +1538,74 @@ branch_prob (bool thunk)
>>>  
>>>    remove_fake_edges ();
>>>  
>>> +  if (profile_condition_flag || profile_arc_flag)
>>> +      gimple_init_gcov_profiler ();
>>> +
>>> +  if (profile_condition_flag)
>>> +    {
>>> +      struct condcov *cov = find_conditions (cfun);
>>> +      gcc_assert (cov);
>>> +      const unsigned nconds = cov_length (cov);
>>> +      total_num_conds += nconds;
>>> +
>>> +      if (coverage_counter_alloc (GCOV_COUNTER_CONDS, 2 * nconds))
>>> +	{
>>> +	  /* Add two extra variables to the function for the local
>>> +	     accumulators, which are zero'd on the entry of a new conditional.
>>> +	     The local accumulators are shared between decisions in order to
>>> +	     use less stack space. */
>>> +	  tree accu[2] = {
>>> +	    build_decl (UNKNOWN_LOCATION, VAR_DECL,
>>> +			get_identifier ("__accu_t"), get_gcov_type ()),
>>> +	    build_decl (UNKNOWN_LOCATION, VAR_DECL,
>>> +			get_identifier ("__accu_f"), get_gcov_type ()),
>>> +	  };
>>> +
>>> +	  gcov_position_t offset {};
>>> +	  if (output_to_file)
>>> +	      offset = gcov_write_tag (GCOV_TAG_CONDS);
>>> +
>>> +	  for (unsigned i = 0; i < nconds; ++i)
>>> +	    {
>>> +	      array_slice<basic_block> expr = cov_blocks (cov, i);
>>> +	      array_slice<gcov_type_unsigned> masks = cov_masks (cov, i);
>>> +	      gcc_assert (expr.is_valid ());
>>> +	      gcc_assert (masks.is_valid ());
>>> +
>>> +	      int terms = instrument_decisions (expr, i, accu, masks.begin ());
>>> +	      if (output_to_file)
>>> +		{
>>> +		  gcov_write_unsigned (expr.front ()->index);
>>> +		  gcov_write_unsigned (terms);
>>> +		}
>>> +	    }
>>> +	  if (output_to_file)
>>> +	      gcov_write_length (offset);
>>> +	}
>>> +      cov_free (cov);
>>> +    }
>>> +
>>>    /* For each edge not on the spanning tree, add counting code.  */
>>>    if (profile_arc_flag
>>>        && coverage_counter_alloc (GCOV_COUNTER_ARCS, num_instrumented))
>>>      {
>>>        unsigned n_instrumented;
>>>  
>>> -      gimple_init_gcov_profiler ();
>>> -
>>>        n_instrumented = instrument_edges (el);
>>>  
>>>        gcc_assert (n_instrumented == num_instrumented);
>>>  
>>>        if (flag_profile_values)
>>>  	instrument_values (values);
>>> -
>>> -      /* Commit changes done by instrumentation.  */
>>> -      gsi_commit_edge_inserts ();
>>>      }
>>>  
>>>    free_aux_for_edges ();
>>>  
>>>    values.release ();
>>>    free_edge_list (el);
>>> +  /* Commit changes done by instrumentation.  */
>>> +  gsi_commit_edge_inserts ();
>>> +
>>>    coverage_end_function (lineno_checksum, cfg_checksum);
>>>    if (flag_branch_probabilities
>>>        && (profile_status_for_fn (cfun) == PROFILE_READ))
>>> @@ -1664,6 +1735,7 @@ init_branch_prob (void)
>>>    total_num_passes = 0;
>>>    total_num_times_called = 0;
>>>    total_num_branches = 0;
>>> +  total_num_conds = 0;
>>>    for (i = 0; i < 20; i++)
>>>      total_hist_br_prob[i] = 0;
>>>  }
>>> @@ -1703,5 +1775,7 @@ end_branch_prob (void)
>>>  		     (total_hist_br_prob[i] + total_hist_br_prob[19-i]) * 100
>>>  		     / total_num_branches, 5*i, 5*i+5);
>>>  	}
>>> +      fprintf (dump_file, "Total number of conditions: %d\n",
>>> +	       total_num_conds);
>>>      }
>>>  }
>>> diff --git a/gcc/testsuite/g++.dg/gcov/gcov-18.C b/gcc/testsuite/g++.dg/gcov/gcov-18.C
>>> new file mode 100644
>>> index 00000000000..310ed5297c0
>>> --- /dev/null
>>> +++ b/gcc/testsuite/g++.dg/gcov/gcov-18.C
>>> @@ -0,0 +1,234 @@
>>> +/* { dg-options "--coverage -fprofile-conditions -std=c++11" } */
>>> +/* { dg-do run { target native } } */
>>> +
>>> +#include <vector>
>>> +#include <stdexcept>
>>> +
>>> +class nontrivial_destructor
>>> +{
>>> +public:
>>> +    explicit nontrivial_destructor (int v) : val (v) {}
>>> +    ~nontrivial_destructor () {}
>>> +
>>> +    explicit operator bool() const { return bool(val); }
>>> +
>>> +    int val;
>>> +};
>>> +
>>> +int identity (int x) { return x; }
>>> +int throws (int) { throw std::runtime_error("exception"); }
>>> +
>>> +int throw_if (int x)
>>> +{
>>> +    if (x) /* conditions(1/2) true(0) */
>>> +	   /* conditions(end) */
>>> +	throw std::runtime_error("exception");
>>> +    return x;
>>> +}
>>> +
>>> +/* used for side effects to insert nodes in conditional bodies etc. */
>>> +int x = 0;
>>> +
>>> +/* conditionals work in the presence of non-trivial destructors */
>>> +void mcdc001a (int a)
>>> +{
>>> +    nontrivial_destructor v (a);
>>> +
>>> +    if (v.val > 0) /* conditions(2/2) */
>>> +	x = v.val;
>>> +    else
>>> +	x = -v.val;
>>> +}
>>> +
>>> +/* non-trivial destructor in-loop temporary */
>>> +nontrivial_destructor
>>> +mcdc002a (int a, int b)
>>> +{
>>> +    for (int i = 0; i < a; i++) /* conditions(2/2) */
>>> +    {
>>> +	nontrivial_destructor tmp (a);
>>> +	if (tmp.val % b) /* conditions(2/2) */
>>> +	    return nontrivial_destructor (0);
>>> +	x += i;
>>> +    } /* conditions(suppress) */
>>> +      /* conditions(end) */
>>> +
>>> +    return nontrivial_destructor (a * b);
>>> +}
>>> +
>>> +/* conditional in constructor */
>>> +void mcdc003a (int a)
>>> +{
>>> +    class C
>>> +    {
>>> +    public:
>>> +	explicit C (int e) : v (e)
>>> +	{
>>> +	    if (e) /* conditions(1/2) false(0) */
>>> +		v = x - e;
>>> +	}
>>> +	int v;
>>> +    };
>>> +
>>> +    C c (a);
>>> +    if (c.v > 2) /* conditions(1/2) true(0) */
>>> +		 /* conditions(end) */
>>> +	x = c.v + a;
>>> +}
>>> +
>>> +/* conditional in destructor */
>>> +void mcdc004a (int a)
>>> +{
>>> +    class C
>>> +    {
>>> +    public:
>>> +	explicit C (int e) : v (e) {}
>>> +	~C ()
>>> +	{
>>> +	    if (v) /* conditions(2/2) */
>>> +		x = 2 * v;
>>> +	}
>>> +	int v;
>>> +    };
>>> +
>>> +    C c (a);
>>> +    x = 1; // arbitrary action between ctor+dtor
>>> +}
>>> +
>>> +/* conditional in try */
>>> +void mcdc005a (int a)
>>> +{
>>> +    try
>>> +    {
>>> +	if (a) /* conditions(1/2) true(0) */
>>> +	       /* conditions(end) */
>>> +	    x = 2 * identity (a);
>>> +	else
>>> +	    x = 1;
>>> +    }
>>> +    catch (...)
>>> +    {
>>> +	x = 0;
>>> +    }
>>> +}
>>> +
>>> +/* conditional in catch */
>>> +void mcdc006a (int a) {
>>> +    try
>>> +    {
>>> +	throws (a);
>>> +    }
>>> +    catch (std::exception&)
>>> +    {
>>> +	if (a) /* conditions(1/2) false(0) */
>>> +	       /* conditions(end) */
>>> +	    x = identity (a);
>>> +	else
>>> +	    x = 0;
>>> +    }
>>> +}
>>> +
>>> +void mcdc006b (int a)
>>> +{
>>> +    if (a) /* conditions(1/2) true(0) */
>>> +	   /* conditions(end) */
>>> +	throws (a);
>>> +    else
>>> +	x = 1;
>>> +}
>>> +
>>> +void mcdc006c (int a) try
>>> +{
>>> +    throws (a);
>>> +}
>>> +catch (...) {
>>> +    if (a) /* conditions(2/2) */
>>> +	x = 5;
>>> +}
>>> +
>>> +/* temporary with destructor as term */
>>> +void mcdc007a (int a, int b)
>>> +{
>>> +    x = a && nontrivial_destructor (b); /* conditions(3/4) false(1) destructor() */
>>> +}
>>> +
>>> +void mcdc007b (int a, int b)
>>> +{
>>> +    if (a || throw_if (b)) /* conditions(3/4) true(1) destructor() */
>>> +	x = -1;
>>> +    else
>>> +	x = 1;
>>> +}
>>> +
>>> +void mcdc007c (int a, int b)
>>> +{
>>> +    if (throw_if (a) || throw_if (b)) /* conditions(2/4) true(0 1) destructor() */
>>> +	x = -1;
>>> +    else
>>> +	x = 1;
>>> +}
>>> +
>>> +/* destructor with delete */
>>> +void mcdc008a (int a)
>>> +{
>>> +    class C
>>> +    {
>>> +    public:
>>> +        int size = 5;
>>> +        int* ptr = nullptr;
>>> +
>>> +        explicit C (int v) : size (v + 5), ptr (new int[size]) /* conditions(suppress) */
>>> +							       /* conditions(end) */
>>> +        {
>>> +	    for (int i = 0; i < size; i++) /* conditions(2/2) */
>>> +		ptr[i] = i + 1;
>>> +        }
>>> +        ~C()
>>> +        {
>>> +	    // delete with implicit nullptr check
>>> +	    delete ptr; /* conditions(1/2) false(0) */
>>> +			/* conditions(end) */
>>> +	}
>>> +    };
>>> +
>>> +    C c (a);
>>> +    if (c.ptr[a + 1]) /* conditions(1/2) false(0) */
>>> +	x = a;
>>> +}
>>> +
>>> +int
>>> +main (void)
>>> +{
>>> +    mcdc001a (0);
>>> +    mcdc001a (1);
>>> +
>>> +    mcdc002a (1, 1);
>>> +    mcdc002a (1, 2);
>>> +
>>> +    mcdc003a (1);
>>> +
>>> +    mcdc004a (0);
>>> +    mcdc004a (1);
>>> +
>>> +    mcdc005a (0);
>>> +
>>> +    mcdc006a (1);
>>> +
>>> +    mcdc006b (0);
>>> +
>>> +    mcdc006c (0);
>>> +    mcdc006c (1);
>>> +
>>> +    mcdc007a (0, 0);
>>> +    mcdc007a (1, 1);
>>> +
>>> +    mcdc007b (0, 0);
>>> +    mcdc007b (1, 0);
>>> +
>>> +    mcdc007c (0, 0);
>>> +
>>> +    mcdc008a (1);
>>> +
>>> +}
>>> +
>>> +/* { dg-final { run-gcov conditions { --conditions gcov-18.C } } } */
>>> diff --git a/gcc/testsuite/gcc.misc-tests/gcov-19.c b/gcc/testsuite/gcc.misc-tests/gcov-19.c
>>> new file mode 100644
>>> index 00000000000..1adff7c76f4
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.misc-tests/gcov-19.c
>>> @@ -0,0 +1,1250 @@
>>> +/* { dg-options "-fprofile-conditions -ftest-coverage" } */
>>> +/* { dg-do run { target native } } */
>>> +
>>> +/* some side effect to stop branches from being pruned */
>>> +int x = 0;
>>> +
>>> +/* || works */
>>> +void
>>> +mcdc001a (int a, int b)
>>> +{
>>> +    if (a || b) /* conditions(1/4) true(0) false(0 1) */
>>> +		/* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc001b (int a, int b)
>>> +{
>>> +    if (a || b) /* conditions(3/4) true(0) */
>>> +		/* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc001c (int a, int b)
>>> +{
>>> +    if (a || b) /* conditions(4/4) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc001d (int a, int b, int c)
>>> +{
>>> +    if (a || b || c) /* conditions(2/6) false(0 1 2) true(2) */
>>> +		     /* conditions(end) */
>>> +	x = 1;
>>> +}
>>> +
>>> +/* && works */
>>> +void
>>> +mcdc002a (int a, int b)
>>> +{
>>> +    if (a && b) /* conditions(1/4) true(0 1) false(0) */
>>> +		/* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc002b (int a, int b)
>>> +{
>>> +    if (a && b) /* conditions(3/4) false(0) */
>>> +		/* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc002c (int a, int b)
>>> +{
>>> +    if (a && b) /* conditions(4/4) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc002d (int a, int b, int c)
>>> +{
>>> +    if (a && b && c) /* conditions(4/6) false(0 2) */
>>> +		     /* conditions(end) */
>>> +	x = 1;
>>> +}
>>> +
>>> +/* negation works */
>>> +void
>>> +mcdc003a (int a, int b)
>>> +{
>>> +    if (!a || !b) /* conditions(2/4) false(0 1) */
>>> +		  /* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +/* single conditionals with and without else */
>>> +void
>>> +mcdc004a (int a)
>>> +{
>>> +    if (a) /* conditions(1/2) true(0) */
>>> +	   /* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc004b (int a)
>>> +{
>>> +    if (a) /* conditions(2/2) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc004c (int a)
>>> +{
>>> +    if (a) /* conditions(1/2) false(0) */
>>> +	   /* conditions(end) */
>>> +	x = 1;
>>> +}
>>> +
>>> +void
>>> +mcdc004d (int a, int b, int c)
>>> +{
>>> +    /* With no else this is interpreted as (a && (b || c)) */
>>> +    if (a)  /* conditions(3/6) true(2) false(1 2)*/
>>> +    {
>>> +	if (b || c)
>>> +	    x = a + b + c;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc004e (int a, int b, int c)
>>> +{
>>> +    /* With the else, this is interpreted as 2 expressions */
>>> +    if (a)  /* conditions(2/2) */
>>> +    {
>>> +	if (b || c) /* conditions(1/4) true(1) false(0 1) */
>>> +	    x = a + b + c;
>>> +    }
>>> +    else
>>> +    {
>>> +	x = c;
>>> +    }
>>> +}
>>> +
>>> +/* mixing && and || works */
>>> +void
>>> +mcdc005a (int a, int b, int c)
>>> +{
>>> +    if ((a && b) || c) /* conditions(1/6) true(0 1) false(0 1 2) */
>>> +		       /* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc005b (int a, int b, int c, int d)
>>> +{
>>> +    /* This is where masking MC/DC gets unintuitive:
>>> +
>>> +       1 1 0 0 => covers 1 (d = 0) as && 0 masks everything to the left
>>> +       1 0 0 0 => covers 2 (b = 0, c = 0) as (a && 0) masks a and d is never
>>> +       evaluated. */
>>> +    if ((a && (b || c)) && d) /* conditions(3/8) true(0 1 2 3) false(0) */
>>> +			      /* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc005c (int a, int b, int c, int d)
>>> +{
>>> +    if (a || (b && c) || d) /* conditions(2/8) true(0 3) false(0 1 2 3) */
>>> +			    /* conditions(end) */
>>> +        x = a + b + c + d;
>>> +}
>>> +
>>> +void
>>> +mcdc005d (int a, int b, int c, int d)
>>> +{
>>> +    /* This test is quite significant - it has a single input
>>> +       (1, 0, 0, 0) and tests specifically for when a multi-term left operand
>>> +       is masked. d = 0 should mask a || b and for the input there are no other
>>> +       sources for masking a (since b = 0). */
>>> +    if ((a || b) && (c || d)) /* conditions(2/8) true(0 1 2 3) false(0 1) */
>>> +			      /* conditions(end) */
>>> +	x = a + b;
>>> +    else
>>> +	x = c + d;
>>> +}
>>> +
>>> +/* nested conditionals */
>>> +void
>>> +mcdc006a (int a, int b, int c, int d, int e)
>>> +{
>>> +    if (a) /* conditions(2/2) */
>>> +    {
>>> +	if (b && c) /* conditions(3/4) false(1) */
>>> +		    /* conditions(end) */
>>> +	    x = 1;
>>> +	else
>>> +	    x = 2;
>>> +    }
>>> +    else
>>> +    {
>>> +	if (c || d) /* conditions(2/4) true(0 1) */
>>> +		    /* conditions(end) */
>>> +	    x = 3;
>>> +	else
>>> +	    x = 4;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc006b (int a, int b, int c)
>>> +{
>>> +    if (a) /* conditions(6/6) */
>>> +	if (b)
>>> +	    if (c)
>>> +		x = a + b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc006c (int a, int b, int c)
>>> +{
>>> +    if (a) /* conditions(2/2) */
>>> +    {
>>> +	if (b) /*conditions(2/2) */
>>> +	{
>>> +	    if (c) /* conditions(2/2) */
>>> +	    {
>>> +		x = a + b + c;
>>> +	    }
>>> +	}
>>> +	else
>>> +	{
>>> +	    x = b;
>>> +	}
>>> +    }
>>> +    else
>>> +    {
>>> +	x = a;
>>> +    }
>>> +}
>>> +
>>> +/* else/if */
>>> +void
>>> +mcdc007a (int a, int b, int c, int d)
>>> +{
>>> +    if (a) /* conditions(2/2) */
>>> +    {
>>> +	if (b) /* conditions(1/2) true(0) */
>>> +	       /* conditions(end) */
>>> +	    x = 1;
>>> +	else
>>> +	    x = 2;
>>> +    }
>>> +    else if (c) /* conditions(2/2) */
>>> +    {
>>> +	if (d) /* conditions(1/2) true(0) */
>>> +	       /* conditions(end) */
>>> +	    x = 3;
>>> +	else
>>> +	    x = 4;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc007b (int a, int b, int c)
>>> +{
>>> +    goto begin;
>>> +then:
>>> +    x = 1;
>>> +    return;
>>> +begin:
>>> +    /* Evaluates to if (a || b || c) x = 1 */
>>> +    if (a)	    /* conditions(5/6) true(2) */
>>> +		    /* conditions(end) */
>>> +	goto then;
>>> +    else if (b)
>>> +	goto then;
>>> +    else if (c)
>>> +	goto then;
>>> +}
>>> +
>>> +void
>>> +mcdc007c (int a, int b, int c)
>>> +{
>>> +    goto begin;
>>> +then1:
>>> +    x = 1;
>>> +    return;
>>> +then2:
>>> +    x = 1;
>>> +    return;
>>> +then3:
>>> +    x = 1;
>>> +    return;
>>> +begin:
>>> +    /* similar to if (a || b || c) x = 1 */
>>> +    if (a) /* conditions(2/2) */
>>> +	goto then1;
>>> +    else if (b) /* conditions(2/2) */
>>> +	goto then2;
>>> +    else if (c) /* conditions(1/2) true(0) */
>>> +		/* conditions(end) */
>>> +	goto then3;
>>> +}
>>> +
>>> +/* while loop */
>>> +void
>>> +mcdc008a (int a)
>>> +{
>>> +    while (a < 10) /* conditions(2/2) */
>>> +	x = a++;
>>> +}
>>> +
>>> +void
>>> +mcdc008b (int a)
>>> +{
>>> +    while (a > 10) /* conditions(1/2) true(0) */
>>> +		   /* conditions(end) */
>>> +	x = a--;
>>> +}
>>> +
>>> +void
>>> +mcdc008c (int a)
>>> +{
>>> +    // should work, even with no body
>>> +    while (a) /* conditions(2/2) */
>>> +	break;
>>> +}
>>> +
>>> +void
>>> +mcdc008d (int a, int b, int c, int d)
>>> +{
>>> +    /* multi-term loop conditional */
>>> +    while ((a && (b || c)) && d) /* conditions(8/8) */
>>> +	a = b = c = d = 0;
>>> +}
>>> +
>>> +void
>>> +mcdc009a (int a, int b)
>>> +{
>>> +    while (a > 0 && b > 0) /* conditions(3/4) false(1) */
>>> +			   /* conditions(end) */
>>> +	x = a--;
>>> +}
>>> +
>>> +/* for loop */
>>> +void
>>> +mcdc010a(int a, int b)
>>> +{
>>> +    for (int i = 0; i < b; i++) /* conditions(2/2) */
>>> +    {
>>> +	if (a < b) /* conditions(2/2) */
>>> +	    x = 1;
>>> +	else
>>> +	    x = a += 2;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc010b ()
>>> +{
>>> +    for (int a = 0; a <= 1; ++a) /* conditions(2/2) */
>>> +    {
>>> +	x = a;
>>> +    }
>>> +}
>>> +
>>> +int always (int x) { (void) x; return 1; }
>>> +
>>> +/* no-condition infinite loops */
>>> +void
>>> +mcdc010c (int a)
>>> +{
>>> +    for (;;)
>>> +    {
>>> +	if (always(a)) /* conditions(1/2) false(0) */
>>> +		       /* conditions(end) */
>>> +	{
>>> +	    x = a;
>>> +	    break;
>>> +	}
>>> +	x += a + 1;
>>> +    }
>>> +}
>>> +
>>> +/* conditionals without control flow constructs work */
>>> +void
>>> +mcdc011a (int a, int b, int c)
>>> +{
>>> +    x = (a && b) || c; /* conditions(5/6) false(1) */
>>> +		       /* conditions(end) */
>>> +}
>>> +
>>> +/* sequential expressions are handled independently */
>>> +void
>>> +mcdc012a (int a, int b, int c)
>>> +{
>>> +    if (a || b) /* conditions(3/4) true(0) */
>>> +		/* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +
>>> +    if (c) /* conditions(2/2) */
>>> +	x = 1;
>>> +}
>>> +
>>> +/*
>>> + * cannot ever satisfy MC/DC, even with all input combinations, because not all
>>> + * variables independently affect the decision
>>> + */
>>> +void
>>> +mcdc013a (int a, int b, int c)
>>> +{
>>> +    (void)b;
>>> +    /*
>>> +     * Specification: (a && b) || c
>>> +     *
>>> +     * But the expression was implemented wrong. This has branch coverage, but
>>> +     * not MC/DC
>>> +     */
>>> +    if ((a && !c) || c) /* conditions(5/6) false(1) */
>>> +	/* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +void
>>> +mcdc014a ()
>>> +{
>>> +    int conds[64] = { 0 };
>>> +    /* conditions(64/128) true(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63) */
>>> +    x = conds[ 0] || conds[ 1] || conds[ 2] || conds[ 3] || conds[ 4] ||
>>> +	conds[ 5] || conds[ 6] || conds[ 7] || conds[ 8] || conds[ 9] ||
>>> +	conds[10] || conds[11] || conds[12] || conds[13] || conds[14] ||
>>> +	conds[15] || conds[16] || conds[17] || conds[18] || conds[19] ||
>>> +	conds[20] || conds[21] || conds[22] || conds[23] || conds[24] ||
>>> +	conds[25] || conds[26] || conds[27] || conds[28] || conds[29] ||
>>> +	conds[30] || conds[31] || conds[32] || conds[33] || conds[34] ||
>>> +	conds[35] || conds[36] || conds[37] || conds[38] || conds[39] ||
>>> +	conds[40] || conds[41] || conds[42] || conds[43] || conds[44] ||
>>> +	conds[45] || conds[46] || conds[47] || conds[48] || conds[49] ||
>>> +	conds[50] || conds[51] || conds[52] || conds[53] || conds[54] ||
>>> +	conds[55] || conds[56] || conds[57] || conds[58] || conds[59] ||
>>> +	conds[60] || conds[61] || conds[62] || conds[63]
>>> +	;  /* conditions(end) */
>>> +}
>>> +
>>> +/* early returns */
>>> +void
>>> +mcdc015a (int a, int b)
>>> +{
>>> +    if (a) /* conditions(2/2) */
>>> +	return;
>>> +
>>> +    if (b) /* conditions(1/2) true(0) */
>>> +	   /* conditions(end) */
>>> +	x = 1;
>>> +}
>>> +
>>> +void
>>> +mcdc015b (int a, int b)
>>> +{
>>> +    for (int i = 5; i > a; i--) /* conditions(2/2) */
>>> +    {
>>> +	if (i == b) /* conditions(2/2) */
>>> +	    return;
>>> +	x = i;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc015c (int a, int b)
>>> +{
>>> +    for (int i = 5; i > a; i--) /* conditions(2/2) */
>>> +    {
>>> +	if (i == b) /* conditions(2/2) */
>>> +	{
>>> +	    x = 0;
>>> +	    return;
>>> +	}
>>> +	else
>>> +	{
>>> +	    x = 1;
>>> +	    return;
>>> +	}
>>> +
>>> +	x = i;
>>> +    }
>>> +}
>>> +
>>> +
>>> +/* check nested loops */
>>> +void
>>> +mcdc016a (int a, int b)
>>> +{
>>> +    for (int i = 0; i < a; i++) /* conditions(2/2) */
>>> +	for (int k = 0; k < b; k++) /* conditions(2/2) */
>>> +	    x = i + k;
>>> +}
>>> +
>>> +void
>>> +mcdc016b (int a, int b)
>>> +{
>>> +    for (int i = 0; i < a; i++) /* conditions(2/2) */
>>> +    {
>>> +	if (a > 5) /* conditions(2/2) */
>>> +	    break;
>>> +
>>> +	for (int k = 0; k < b; k++) /* conditions(2/2) */
>>> +	    x = i + k;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc016c (int a, int b)
>>> +{
>>> +    for (int i = 0; i < a; i++) /* conditions(2/2) */
>>> +    {
>>> +	if (a > 5) /* conditions(1/2) true(0) */
>>> +		   /* conditions(end) */
>>> +	    return;
>>> +
>>> +	for (int k = 0; k < b; k++) /* conditions(2/2) */
>>> +	    x = i + k;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc016d (int a, int b)
>>> +{
>>> +    for (int i = 0; i < a; i++) /* conditions(2/2) */
>>> +    {
>>> +	for (int k = 0; k < 5; k++) /* conditions(2/2) */
>>> +	{
>>> +	    if (b > 5) /* conditions(1/2) true(0) */
>>> +		       /* conditions(end) */
>>> +		return;
>>> +	    x = i + k;
>>> +	}
>>> +
>>> +    }
>>> +}
>>> +
>>> +/* do-while loops */
>>> +void
>>> +mcdc017a (int a)
>>> +{
>>> +    do
>>> +    {
>>> +	a--;
>>> +    } while (a > 0); /* conditions(2/2) */
>>> +}
>>> +
>>> +void
>>> +noop () {}
>>> +
>>> +void
>>> +mcdc017b (int a, int b)
>>> +{
>>> +    do
>>> +    {
>>> +	/*
>>> +	 * This call is important; it can add more nodes to the body in the
>>> +	 * CFG, which has changes how close exits and breaks are to the loop
>>> +	 * conditional.
>>> +	 */
>>> +	noop ();
>>> +	a--;
>>> +	if (b) /* conditions(2/2) */
>>> +	    break;
>>> +
>>> +    } while (a > 0); /* conditions(2/2) */
>>> +}
>>> +
>>> +void
>>> +mcdc017c (int a, int b)
>>> +{
>>> +    int left = 0;
>>> +    int right = 0;
>>> +    int n = a + b;
>>> +    do
>>> +    {
>>> +	if (a) /* conditions(1/2) false(0) */
>>> +	       /* conditions(end) */
>>> +	{
>>> +	    left = a > left ? b : left; /* conditions(2/2) */
>>> +	}
>>> +	if (b) /* conditions(1/2) false(0) */
>>> +	{
>>> +	    right = b > right ? a : right; /* conditions(2/2) */
>>> +	}
>>> +    } while (n-- > 0); /* conditions(2/2) */
>>> +}
>>> +
>>> +int id  (int x) { return  x; }
>>> +int inv (int x) { return !x; }
>>> +
>>> +/* collection of odd cases lifted-and-adapted from real-world code */
>>> +int mcdc018a (int a, int b, int c, int d, int e, int f, int g, int len)
>>> +{
>>> +    int n;
>>> +    /* adapted from zlib/gz_read */
>>> +    do
>>> +    {
>>> +	n = -1;
>>> +	if (n > len) /* conditions(2/2) */
>>> +	    n = len;
>>> +
>>> +	if (b) /* conditions(2/2) */
>>> +	{
>>> +	    if (b < 5) /* conditions(2/2) */
>>> +		x = 1;
>>> +	    noop();
>>> +	}
>>> +	else if (c && d) /* conditions(3/4) false(1) */
>>> +	{
>>> +	    x = 2;
>>> +	    break;
>>> +	}
>>> +	else if (e || f) /* conditions(2/4) false(0 1) */
>>> +			 /* conditions(end) */
>>> +	{
>>> +	    if (id(g)) /* conditions(2/2) */
>>> +		return 0;
>>> +	    continue;
>>> +	}
>>> +    } while (a-- > 0); /* conditions(2/2) */
>>> +
>>> +    return 1;
>>> +}
>>> +
>>> +void
>>> +mcdc018b (int a, int b, int c)
>>> +{
>>> +    int n;
>>> +    while (a) /* conditions(2/2) */
>>> +    {
>>> +	/* else block does not make a difference for the problem, but ensures
>>> +	   loop termination. */
>>> +	if (b) /* conditions(2/2) */
>>> +	    n = c ? 0 : 0; // does not show up in CFG (embedded in the block)
>>> +	else
>>> +	    n = 0;
>>> +	a = n;
>>> +    }
>>> +}
>>> +
>>> +/* Adapted from zlib/compress2 */
>>> +void
>>> +mcdc018c (int a, int b)
>>> +{
>>> +    int err;
>>> +    do
>>> +    {
>>> +	a = inv (a);
>>> +	err = a;
>>> +    } while (err); /* conditions(1/2) true(0) */
>>> +		   /* conditions(end) */
>>> +
>>> +    a = id (a);
>>> +    if (a) /* conditions(1/2) true(0) */
>>> +	x *= a + 1;
>>> +}
>>> +
>>> +/* too many conditions, coverage gives up */
>>> +void
>>> +mcdc019a ()
>>> +{
>>> +    int conds[65] = { 0 };
>>> +    #pragma GCC diagnostic push
>>> +    #pragma GCC diagnostic ignored "-Wcoverage-too-many-conditions"
>>> +    x = conds[ 0] || conds[ 1] || conds[ 2] || conds[ 3] || conds[ 4] ||
>>> +	conds[ 5] || conds[ 6] || conds[ 7] || conds[ 8] || conds[ 9] ||
>>> +	conds[10] || conds[11] || conds[12] || conds[13] || conds[14] ||
>>> +	conds[15] || conds[16] || conds[17] || conds[18] || conds[19] ||
>>> +	conds[20] || conds[21] || conds[22] || conds[23] || conds[24] ||
>>> +	conds[25] || conds[26] || conds[27] || conds[28] || conds[29] ||
>>> +	conds[30] || conds[31] || conds[32] || conds[33] || conds[34] ||
>>> +	conds[35] || conds[36] || conds[37] || conds[38] || conds[39] ||
>>> +	conds[40] || conds[41] || conds[42] || conds[43] || conds[44] ||
>>> +	conds[45] || conds[46] || conds[47] || conds[48] || conds[49] ||
>>> +	conds[50] || conds[51] || conds[52] || conds[53] || conds[54] ||
>>> +	conds[55] || conds[56] || conds[57] || conds[58] || conds[59] ||
>>> +	conds[60] || conds[61] || conds[62] || conds[63] || conds[64]
>>> +	;
>>> +    #pragma GCC diagnostic pop
>>> +}
>>> +
>>> +/* ternary */
>>> +void
>>> +mcdc020a (int a)
>>> +{
>>> +    // special case, this can be reduced to:
>>> +    // _1 = argc != 0;
>>> +    // e = (int) _1;
>>> +    x = a ? 1 : 0;
>>> +
>>> +    // changing to different int makes branch
>>> +    x = a ? 2 : 1; /* conditions(2/2) */
>>> +}
>>> +
>>> +void
>>> +mcdc020b (int a, int b)
>>> +{
>>> +    x = (a || b) ? 1 : 0; /* conditions(3/4) true(1) */
>>> +}
>>> +
>>> +void
>>> +mcdc020c (int a, int b)
>>> +{
>>> +    x = a ? 0
>>> +	: b ? 1 /* conditions(2/2) */
>>> +	: 2;    /* conditions(1/2) false(0) */
>>> +		/* conditions(end) */
>>> +}
>>> +
>>> +/* Infinite loop (no exit-edge), this should not be called, but it should
>>> +   compile fine */
>>> +void
>>> +mcdc021a ()
>>> +{
>>> +    while (1)
>>> +	;
>>> +}
>>> +
>>> +/* Computed goto can give all sorts of problems, including difficult path
>>> +   contractions. */
>>> +void
>>> +mcdc021b ()
>>> +{
>>> +  void *op = &&dest;
>>> +dest:
>>> +  if (op) /* conditions(0/2) true(0) false(0) */
>>> +	  /* conditions(end) */
>>> +    goto * 0;
>>> +}
>>> +
>>> +int __sigsetjmp ();
>>> +
>>> +/* This should compile, but not called. */
>>> +void
>>> +mcdc021c ()
>>> +{
>>> +  while (x) /* conditions(0/2) true(0) false(0)*/
>>> +	    /* conditions(end) */
>>> +     __sigsetjmp ();
>>> +}
>>> +
>>> +/* If edges are not properly contracted the a && id (b) will be interpreted as
>>> +   two independent expressions. */
>>> +void
>>> +mcdc021d (int a, int b, int c, int d)
>>> +{
>>> +    if (a && id (b)) /* conditions(1/4) true(0 1) false(0) */
>>> +		     /* conditions(end) */
>>> +	x = 1;
>>> +    else if (c && id (d)) /* conditions(1/4) true(0 1) false(0) */
>>> +			  /* conditions(end) */
>>> +	x = 2;
>>> +    else
>>> +	x = 3;
>>> +}
>>> +
>>> +/* Adapted from linux arch/x86/tools/relocs.c
>>> +   With poor edge contracting this became an infinite loop. */
>>> +void
>>> +mcdc022a (int a, int b)
>>> +{
>>> +    for (int i = 0; i < 5; i++) /* conditions(2/2) */
>>> +    {
>>> +	x = i;
>>> +	for (int j = i; j < 5; j++) /* conditions(2/2) */
>>> +	{
>>> +	    if (id (id (a)) || id (b)) /* conditions(3/4) true(0) */
>>> +				       /* conditions(end) */
>>> +		continue;
>>> +	    b = inv(b);
>>> +	}
>>> +    }
>>> +}
>>> +
>>> +int
>>> +mcdc022b (int a)
>>> +{
>>> +    int devt;
>>> +    if (a) /* conditions(2/2) */
>>> +    {
>>> +	x = a * 2;
>>> +	if (x != a / 10 || x != a % 10) /* conditions(1/4) true(1) false(0 1) */
>>> +					/* conditions(end) */
>>> +	    return 0;
>>> +    } else {
>>> +	devt = id (a);
>>> +	if (devt) /* conditions(1/2) true(0) */
>>> +		  /* conditions(end) */
>>> +	    return 0;
>>> +    }
>>> +
>>> +    return devt;
>>> +}
>>> +
>>> +/* Adapted from linux arch/x86/events/intel/ds.c
>>> +
>>> +   It broken sorting so that the entry block was not the first node after
>>> +   sorting. */
>>> +void
>>> +mcdc022c (int a)
>>> +{
>>> +    if (!a) /* conditions(2/2) */
>>> +	return;
>>> +
>>> +    for (int i = 0; i < 5; i++) /* conditions(2/2) */
>>> +    {
>>> +	if (id (a + i) || inv (a - 1)) /* conditions(1/4) false(0 1) true(1) */
>>> +				       /* conditions(end) */
>>> +	    x = a + i;
>>> +	if (inv (a)) /* conditions(1/2) true(0) */
>>> +		     /* conditions(end) */
>>> +	    break;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc022d (int a)
>>> +{
>>> +    int i;
>>> +    for (i = 0; i < id (a); i++) /* conditions(1/2) false(0) */
>>> +    {
>>> +	if (!inv (a)) /* conditions(1/2) false(0)*/
>>> +		      /* conditions(end) */
>>> +	    break;
>>> +    }
>>> +
>>> +    if (i < a) /* conditions(1/2) false(0) */
>>> +	       /* conditions(end) */
>>> +	x = a + 1;
>>> +}
>>> +
>>> +/* 023 specifically tests that masking works correctly, which gets complicated
>>> +   fast with a mix of operators and deep subexpressions.  These tests violates
>>> +   the style guide slightly to emphasize the nesting.  They all share the same
>>> +   implementation and only one input is given to each function to obtain clean
>>> +   coverage results. */
>>> +void
>>> +mcdc023a (int a, int b, int c, int d, int e, int f, int g, int h, int i, int k,
>>> +	  int l, int m, int n)
>>> +{
>>> +    // [a m n] = 0, [b, ...] = 1
>>> +    // a is masked by b and the remaining terms should be short circuited
>>> +    if (/* conditions(1/24) true(0 2 3 4 5 6 7 8 9 10 11) false(0 1 2 3 4 5 6 7 8 9 10 11) */
>>> +	/* conditions(end) */
>>> +	   (a || b)
>>> +	|| (   ((c && d) || (e && (f || g) && h))
>>> +	    && (k || l)
>>> +	    && (m || n)))
>>> +	x = a + b;
>>> +    else
>>> +	x = b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc023b (int a, int b, int c, int d, int e, int f, int g, int h, int i, int k,
>>> +	  int l, int m, int n)
>>> +{
>>> +    // [a b d h] = 0, [c, ...] = 1
>>> +    // h = 0 => false but does not mask (a || b) or (c && d). d = 0 masks c.
>>> +    if (/* conditions(4/24) true(0 1 2 3 4 5 6 7 8 9 10 11) false(2 4 5 6 8 9 10 11) */
>>> +	/* conditions(end) */
>>> +	   (a || b)
>>> +	|| (   ((c && d) || (e && (f || g) && h))
>>> +	    && (k || l)
>>> +	    && (m || n)))
>>> +	x = a + b;
>>> +    else
>>> +	x = b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc023c (int a, int b, int c, int d, int e, int f, int g, int h, int i, int k,
>>> +	  int l, int m, int n)
>>> +{
>>> +    /* [m n a b] = 0, [...] = 1
>>> +       n,m = 0 should mask all other terms than a, b */
>>> +    if (/* conditions(4/24) true(0 1 2 3 4 5 6 7 8 9 10 11) false(2 3 4 5 6 7 8 9) */
>>> +	/* conditions(end) */
>>> +	   (a || b)
>>> +	|| (   ((c && d) || (e && (f || g) && h))
>>> +	    && (k || l)
>>> +	    && (m || n)))
>>> +	x = a + b;
>>> +    else
>>> +	x = b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc023d (int a, int b, int c, int d, int e, int f, int g, int h, int i, int k,
>>> +	  int l, int m, int n)
>>> +{
>>> +    /* [a b] = 0, [h, ...] = 1
>>> +       n,m = 0 should mask all other terms than a, b */
>>> +    if (/* conditions(4/24) true(0 1 2 3 4 5 6 7 8 9 10 11) false(2 3 4 5 6 7 10 11) */
>>> +	/* conditions(end) */
>>> +	   (a || b)
>>> +	|| (   ((c && d) || (e && (f || g) && h))
>>> +	    && (k || l)
>>> +	    && (m || n)))
>>> +	x = a + b;
>>> +    else
>>> +	x = b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc023e (int a, int b, int c, int d, int e, int f, int g, int h, int i, int k,
>>> +	  int l, int m, int n)
>>> +{
>>> +    /* [a b d] = 0, [c h, ...] = 1
>>> +       h = 1 should mask c, d, leave other terms intact.
>>> +       If [k l m n] were false then h itself would be masked.
>>> +       [a b] are masked as collateral by [m n]. */
>>> +    if (/* conditions(5/24) true(0 1 2 3 6 9 11) false(0 1 2 3 4 5 6 7 8 9 10 11) */
>>> +	/* conditions(end) */
>>> +	   (a || b)
>>> +	|| (   ((c && d) || (e && (f || g) && h))
>>> +	    && (k || l)
>>> +	    && (m || n)))
>>> +	x = a + b;
>>> +    else
>>> +	x = b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc023f (int a, int b, int c, int d, int e, int f, int g, int h, int i, int k,
>>> +	  int l, int m, int n)
>>> +{
>>> +    /* [a b c f g] = 0, [e, ...] = 1
>>> +       [f g] = 0 should mask e, leave [c d] intact. */
>>> +    if (/* conditions(5/24) true(0 1 2 3 4 5 6 7 8 9 10 11) false(3 4 7 8 9 10 11) */
>>> +	/* conditions(end) */
>>> +	   (a || b)
>>> +	|| (   ((c && d) || (e && (f || g) && h))
>>> +	    && (k || l)
>>> +	    && (m || n)))
>>> +	x = a + b;
>>> +    else
>>> +	x = b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc023g (int a, int b, int c, int d, int e, int f, int g, int h, int i, int k,
>>> +	  int l, int m, int n)
>>> +{
>>> +    /* [a b d f g] = 0, [e c, ...] = 1
>>> +       Same as 023f but with [c d] flipped so d masks c rather than c
>>> +       short-circuits.  This should not be lost. */
>>> +    if (/* conditions(5/24) true(0 1 2 3 4 5 6 7 8 9 10 11) false(2 4 7 8 9 10 11) */
>>> +	/* conditions(end) */
>>> +	   (a || b)
>>> +	|| (   ((c && d) || (e && (f || g) && h))
>>> +	    && (k || l)
>>> +	    && (m || n)))
>>> +	x = a + b;
>>> +    else
>>> +	x = b + c;
>>> +}
>>> +
>>> +void
>>> +mcdc024a (int a, int b)
>>> +{
>>> +    if (a && b) /* conditions(1/4) true(0 1) false(1) */
>>> +		/* conditions(end) */
>>> +    {
>>> +label1:
>>> +	x = 1;
>>> +    }
>>> +    else
>>> +    {
>>> +	x = 2;
>>> +    }
>>> +
>>> +    if (a || b) /* conditions(2/4) true(0 1) */
>>> +		/* conditions(end) */
>>> +    {
>>> +label2:
>>> +	x = 1;
>>> +    }
>>> +    else
>>> +    {
>>> +	x = 2;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc024b (int a, int b)
>>> +{
>>> +
>>> +    if (a && b) /* conditions(1/4) true(0 1) false(1) */
>>> +		/* conditions(end) */
>>> +    {
>>> +	x = 1;
>>> +    }
>>> +    else
>>> +    {
>>> +label1:
>>> +	x = 2;
>>> +    }
>>> +
>>> +    if (a || b) /* conditions(2/4) true(0 1) */
>>> +		/* conditions(end) */
>>> +    {
>>> +	x = 1;
>>> +    }
>>> +    else
>>> +    {
>>> +label2:
>>> +	x = 2;
>>> +    }
>>> +}
>>> +
>>> +void
>>> +mcdc024c (int a, int b)
>>> +{
>>> +    if (a && b) /* conditions(1/4) true(0 1) false(1) */
>>> +		/* conditions(end) */
>>> +    {
>>> +label1:
>>> +	x = 1;
>>> +    }
>>> +    else
>>> +    {
>>> +label2:
>>> +	x = 2;
>>> +    }
>>> +
>>> +    if (a || b) /* conditions(2/4) true(0 1) */
>>> +		/* conditions(end) */
>>> +    {
>>> +label3:
>>> +	x = 1;
>>> +    }
>>> +    else
>>> +    {
>>> +label4:
>>> +	x = 2;
>>> +    }
>>> +}
>>> +
>>> +int main ()
>>> +{
>>> +    mcdc001a (0, 1);
>>> +
>>> +    mcdc001b (0, 1);
>>> +    mcdc001b (0, 0);
>>> +
>>> +    mcdc001c (0, 1);
>>> +    mcdc001c (0, 0);
>>> +    mcdc001c (1, 1);
>>> +
>>> +    mcdc001d (1, 1, 1);
>>> +    mcdc001d (0, 1, 0);
>>> +
>>> +    mcdc002a (1, 0);
>>> +
>>> +    mcdc002b (1, 0);
>>> +    mcdc002b (1, 1);
>>> +
>>> +    mcdc002c (0, 0);
>>> +    mcdc002c (1, 1);
>>> +    mcdc002c (1, 0);
>>> +
>>> +    mcdc002d (1, 1, 1);
>>> +    mcdc002d (1, 0, 0);
>>> +
>>> +    mcdc003a (0, 0);
>>> +    mcdc003a (1, 0);
>>> +
>>> +    mcdc004a (0);
>>> +    mcdc004b (0);
>>> +    mcdc004b (1);
>>> +    mcdc004c (1);
>>> +
>>> +    mcdc004d (0, 0, 0);
>>> +    mcdc004d (1, 1, 1);
>>> +
>>> +    mcdc004e (0, 0, 0);
>>> +    mcdc004e (1, 1, 1);
>>> +
>>> +    mcdc005a (1, 0, 1);
>>> +
>>> +    mcdc005b (1, 1, 0, 0);
>>> +    mcdc005b (1, 0, 0, 0);
>>> +
>>> +    mcdc005c (0, 1, 1, 0);
>>> +
>>> +    mcdc005d (1, 0, 0, 0);
>>> +
>>> +    mcdc006a (0, 0, 0, 0, 0);
>>> +    mcdc006a (1, 0, 0, 0, 0);
>>> +    mcdc006a (1, 1, 1, 0, 0);
>>> +
>>> +    mcdc006b (0, 0, 0);
>>> +    mcdc006b (1, 0, 0);
>>> +    mcdc006b (1, 1, 0);
>>> +    mcdc006b (1, 1, 1);
>>> +
>>> +    mcdc006c (0, 0, 0);
>>> +    mcdc006c (1, 0, 0);
>>> +    mcdc006c (1, 1, 0);
>>> +    mcdc006c (1, 1, 1);
>>> +
>>> +    mcdc007a (0, 0, 0, 0);
>>> +    mcdc007a (1, 0, 0, 0);
>>> +    mcdc007a (0, 0, 1, 0);
>>> +
>>> +    mcdc007b (0, 0, 0);
>>> +    mcdc007b (0, 1, 1);
>>> +    mcdc007b (1, 0, 1);
>>> +
>>> +    mcdc007c (0, 0, 0);
>>> +    mcdc007c (0, 1, 1);
>>> +    mcdc007c (1, 0, 1);
>>> +
>>> +    mcdc008a (0);
>>> +
>>> +    mcdc008b (0);
>>> +
>>> +    mcdc008c (0);
>>> +    mcdc008c (1);
>>> +
>>> +    mcdc008d (0, 0, 0, 0);
>>> +    mcdc008d (1, 0, 0, 0);
>>> +    mcdc008d (1, 0, 1, 0);
>>> +    mcdc008d (1, 0, 1, 1);
>>> +    mcdc008d (1, 1, 1, 1);
>>> +
>>> +    mcdc009a (0, 0);
>>> +    mcdc009a (1, 1);
>>> +
>>> +    mcdc010a (0, 0);
>>> +    mcdc010a (0, 9);
>>> +    mcdc010a (2, 1);
>>> +
>>> +    mcdc010b ();
>>> +
>>> +    mcdc010c (1);
>>> +
>>> +    mcdc011a (0, 0, 0);
>>> +    mcdc011a (1, 1, 0);
>>> +    mcdc011a (1, 0, 1);
>>> +
>>> +    mcdc012a (0, 0, 0);
>>> +    mcdc012a (0, 1, 1);
>>> +
>>> +    mcdc013a (0, 0, 0);
>>> +    mcdc013a (0, 0, 1);
>>> +    mcdc013a (0, 1, 0);
>>> +    mcdc013a (0, 1, 1);
>>> +    mcdc013a (1, 0, 0);
>>> +    mcdc013a (1, 0, 1);
>>> +    mcdc013a (1, 1, 0);
>>> +    mcdc013a (1, 1, 1);
>>> +
>>> +    mcdc014a ();
>>> +
>>> +    mcdc015a (0, 0);
>>> +    mcdc015a (1, 0);
>>> +
>>> +    mcdc015b (0, 0);
>>> +    mcdc015b (0, 1);
>>> +    mcdc015b (6, 1);
>>> +
>>> +    mcdc015c (0, 0);
>>> +    mcdc015c (0, 5);
>>> +    mcdc015c (6, 1);
>>> +
>>> +    mcdc016a (5, 5);
>>> +
>>> +    mcdc016b (5, 5);
>>> +    mcdc016b (6, 5);
>>> +
>>> +    mcdc016c (5, 5);
>>> +
>>> +    mcdc016d (1, 0);
>>> +
>>> +    mcdc017a (0);
>>> +    mcdc017a (2);
>>> +
>>> +    mcdc017b (2, 0);
>>> +    mcdc017b (0, 1);
>>> +
>>> +    mcdc017c (1, 1);
>>> +
>>> +    mcdc018a (0, 0, 1, 1, 0, 0, 0, 0);
>>> +    mcdc018a (0, 1, 0, 0, 0, 0, 1, -2);
>>> +    mcdc018a (0, 6, 0, 0, 0, 0, 1, -2);
>>> +    mcdc018a (0, 6, 0, 0, 0, 0, 1, -2);
>>> +    mcdc018a (0, 0, 0, 1, 0, 1, 1, 0);
>>> +    mcdc018a (1, 0, 0, 0, 1, 1, 0, 0);
>>> +
>>> +    mcdc018b (1, 0, 0);
>>> +    mcdc018b (1, 1, 0);
>>> +
>>> +    mcdc018c (1, 1);
>>> +
>>> +    mcdc019a ();
>>> +
>>> +    mcdc020a (0);
>>> +    mcdc020a (1);
>>> +
>>> +    mcdc020b (0, 0);
>>> +    mcdc020b (1, 0);
>>> +
>>> +    mcdc020c (0, 1);
>>> +    mcdc020c (1, 1);
>>> +
>>> +    mcdc021d (1, 0, 1, 0);
>>> +
>>> +    mcdc022a (0, 0);
>>> +
>>> +    mcdc022b (0);
>>> +    mcdc022b (1);
>>> +
>>> +    mcdc022c (0);
>>> +    mcdc022c (1);
>>> +
>>> +    mcdc022d (1);
>>> +
>>> +    mcdc023a (0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1);
>>> +    mcdc023b (0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1);
>>> +    mcdc023c (0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0);
>>> +    mcdc023d (0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1);
>>> +    mcdc023e (0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1);
>>> +    mcdc023f (0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1);
>>> +    mcdc023g (0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1);
>>> +
>>> +    mcdc024a (0, 0);
>>> +    mcdc024b (0, 0);
>>> +    mcdc024c (0, 0);
>>> +}
>>> +
>>> +/* { dg-final { run-gcov conditions { --conditions gcov-19.c } } } */
>>> diff --git a/gcc/testsuite/gcc.misc-tests/gcov-20.c b/gcc/testsuite/gcc.misc-tests/gcov-20.c
>>> new file mode 100644
>>> index 00000000000..847dae495db
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.misc-tests/gcov-20.c
>>> @@ -0,0 +1,22 @@
>>> +/* { dg-options "-fprofile-conditions -ftest-coverage -fprofile-update=atomic" } */
>>> +/* { dg-do run { target native } } */
>>> +
>>> +/* some side effect to stop branches from being pruned */
>>> +int x = 0;
>>> +
>>> +void
>>> +conditions_atomic001 (int a, int b)
>>> +{
>>> +    if (a || b) /* conditions(1/4) true(0) false(0 1) */
>>> +		/* conditions(end) */
>>> +	x = 1;
>>> +    else
>>> +	x = 2;
>>> +}
>>> +
>>> +int main ()
>>> +{
>>> +    conditions_atomic001 (0, 1);
>>> +}
>>> +
>>> +/* { dg-final { run-gcov conditions { --conditions gcov-20.c } } } */
>>> diff --git a/gcc/testsuite/gcc.misc-tests/gcov-21.c b/gcc/testsuite/gcc.misc-tests/gcov-21.c
>>> new file mode 100644
>>> index 00000000000..978be3276a2
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.misc-tests/gcov-21.c
>>> @@ -0,0 +1,16 @@
>>> +/* { dg-options "-fprofile-conditions" } */
>>> +
>>> +/* https://gcc.gnu.org/pipermail/gcc-patches/2022-April/592927.html */
>>> +char trim_filename_name;
>>> +int r;
>>> +
>>> +void trim_filename() {
>>> +    if (trim_filename_name)
>>> +	r = 123;
>>> +    while (trim_filename_name)
>>> +	;
>>> +}
>>> +
>>> +int main ()
>>> +{
>>> +}
>>> diff --git a/gcc/testsuite/lib/gcov.exp b/gcc/testsuite/lib/gcov.exp
>>> index 9d5b2cdb86b..69168d67d03 100644
>>> --- a/gcc/testsuite/lib/gcov.exp
>>> +++ b/gcc/testsuite/lib/gcov.exp
>>> @@ -174,6 +174,184 @@ proc verify-branches { testname testcase file } {
>>>      return $failed
>>>  }
>>>  
>>> +#
>>> +# verify-conditions -- check that conditions are checked as expected
>>> +#
>>> +# TESTNAME is the name of the test, including unique flags.
>>> +# TESTCASE is the name of the test file.
>>> +# FILE is the name of the gcov output file.
>>> +#
>>> +# Checks are based on comments in the source file. Condition coverage comes
>>> +# with with two types of output, a summary and a list of the uncovered
>>> +# conditions. Both must be checked to pass the test
>>> +#
>>> +# To check for conditions, add a comment the line of a conditional:
>>> +# /* conditions(n/m) true(0 1) false(1) */
>>> +#
>>> +# where n/m are the covered and total conditions in the expression. The true()
>>> +# and false() take the indices expected *not* covered.
>>> +#
>>> +# This means that all coverage statements should have been seen:
>>> +# /* conditions(end) */
>>> +#
>>> +# If all conditions are covered i.e. n == m, then conditions(end) can be
>>> +# omitted. If either true() or false() are empty they can be omitted too.
>>> +#
>>> +# C++ can insert conditionals in the CFG that are not present in source code.
>>> +# These must be manually suppressed since unexpected and unhandled conditions
>>> +# are an error (to help combat regressions). Output can be suppressed with
>>> +# conditions(suppress) and conditions(end). suppress should usually be on a
>>> +# closing brace.
>>> +#
>>> +# Some expressions, when using unnamed temporaries as operands, will have
>>> +# destructors in expressions. The coverage of the destructor will be reported
>>> +# on the same line as the expression itself, but suppress() would also swallow
>>> +# the expected tested-for messages. To handle these, use the destructor() [1]
>>> +# which will suppress everything from and including the second "conditions
>>> +# covered".
>>> +#
>>> +# [1] it is important that the destructor() is *on the same line* as the
>>> +#     conditions(m/n)
>>> +proc verify-conditions { testname testcase file } {
>>> +    set failed 0
>>> +    set suppress 0
>>> +    set destructor 0
>>> +    set should ""
>>> +    set shouldt ""
>>> +    set shouldf ""
>>> +    set shouldall ""
>>> +    set fd [open $file r]
>>> +    set n 0
>>> +    set keywords {"end" "suppress"}
>>> +    while {[gets $fd line] >= 0} {
>>> +	regexp "^\[^:\]+: *(\[0-9\]+):" "$line" all n
>>> +	set prefix "$testname line $n"
>>> +
>>> +	if {![regexp "condition" $line]} {
>>> +	    continue
>>> +	}
>>> +
>>> +	# Missing coverage for both true and false will cause a failure, but
>>> +	# only count it once for the report.
>>> +	set ok 1
>>> +	if [regexp {conditions *\(([0-9a-z/]+)\)} "$line" all e] {
>>> +	    # *Very* coarse sanity check: conditions() should either be a
>>> +	    # keyword or n/m, anything else means a buggy test case. end is
>>> +	    # optional for cases where all conditions are covered, since it
>>> +	    # only expects a single line of output.
>>> +	    if {([lsearch -exact $keywords $e] >= 0 || [regexp {\d+/\d+} "$e"]) == 0} {
>>> +		fail "$prefix: expected conditions (n/m), (suppress) or (end); was ($e)"
>>> +		incr failed
>>> +		continue
>>> +	    }
>>> +
>>> +	    # Any keyword means a new context. Set the error flag if not all
>>> +	    # expected output has been seen, and reset the state.
>>> +
>>> +	    if {[llength $shouldt] != 0} {
>>> +		fail "$prefix: expected 'not covered (true)' for terms: $shouldt"
>>> +		set ok 0
>>> +	    }
>>> +
>>> +	    if {[llength $shouldf] != 0} {
>>> +		fail "$prefix: expected 'not covered (false)' for terms: $shouldf"
>>> +		set ok 0
>>> +	    }
>>> +
>>> +	    if {$shouldall ne ""} {
>>> +		fail "$prefix: coverage summary not found; expected $shouldall"
>>> +		set ok 0
>>> +	    }
>>> +
>>> +	    set suppress 0
>>> +	    set destructor 0
>>> +	    set should ""
>>> +	    set shouldt ""
>>> +	    set shouldf ""
>>> +	    set shouldall ""
>>> +	    set newt ""
>>> +	    set newf ""
>>> +
>>> +	    if [regexp {destructor\(\)} "$line"] {
>>> +		set destructor 1
>>> +	    }
>>> +
>>> +	    if [regexp {(\d+)/(\d+)} "$e" all i k] {
>>> +		regexp {true\(([0-9 ]+)\)}  "$line" all newt
>>> +		regexp {false\(([0-9 ]+)\)} "$line" all newf
>>> +
>>> +		# Sanity check - if the true() and false() vectors should have
>>> +		# m-n elements to cover all uncovered conditions. Because of
>>> +		# masking it can sometimes be surprising what terms are
>>> +		# independent, so this makes for more robust test at the cost
>>> +		# of being slightly more annoying to write.
>>> +		set nterms [expr [llength $newt] + [llength $newf]]
>>> +		set nexpected [expr {$k - $i}]
>>> +		if {$nterms != $nexpected} {
>>> +		    fail "$prefix: expected $nexpected uncovered terms; got $nterms"
>>> +		    set ok 0
>>> +		}
>>> +		set shouldall $e
>>> +		set shouldt $newt
>>> +		set shouldf $newf
>>> +	    } elseif {$e == "end"} {
>>> +		# no-op - state has already been reset, and errors flagged
>>> +	    } elseif {$e == "suppress"} {
>>> +		set suppress 1
>>> +	    } else {
>>> +		# this should be unreachable, 
>>> +		fail "$prefix: unhandled control ($e), should be unreachable"
>>> +		set ok 0
>>> +	    }
>>> +	} elseif {$suppress == 1} {
>>> +	    # ignore everything in a suppress block. C++ especially can insert
>>> +	    # conditionals in exceptions and destructors which would otherwise
>>> +	    # be considered unhandled.
>>> +	    continue
>>> +	} elseif [regexp {condition +(\d+) not covered \((.*)\)} "$line" all cond condv] {
>>> +	    foreach v {true false} {
>>> +		if [regexp $v $condv] {
>>> +		    if {"$v" == "true"} {
>>> +			set should shouldt
>>> +		    } else {
>>> +			set should shouldf
>>> +		    }
>>> +
>>> +		    set i [lsearch [set $should] $cond]
>>> +		    if {$i != -1} {
>>> +			set $should [lreplace [set $should] $i $i]
>>> +		    } else {
>>> +			fail "$testname line $n: unexpected uncovered term $cond ($v)"
>>> +			set ok 0
>>> +		    }
>>> +		}
>>> +	    }
>>> +	} elseif [regexp {condition outcomes covered (\d+/\d+)} "$line" all cond] {
>>> +	    # the destructor-generated "conditions covered" lines will be
>>> +	    # written after all expression-related output. Handle these by
>>> +	    # turning on suppression if the destructor-suppression is
>>> +	    # requested.
>>> +	    if {$shouldall == "" && $destructor == 1} {
>>> +		set suppress 1
>>> +		continue
>>> +	    }
>>> +
>>> +	    if {$cond == $shouldall} {
>>> +		set shouldall ""
>>> +	    } else {
>>> +		fail "$testname line $n: unexpected summary $cond"
>>> +		set ok 0
>>> +	    }
>>> +	}
>>> +
>>> +	if {$ok != 1} {
>>> +	    incr failed
>>> +	}
>>> +    }
>>> +    close $fd
>>> +    return $failed
>>> +}
>>> +
>>>  #
>>>  # verify-calls -- check that call return percentages are as expected
>>>  #
>>> @@ -321,6 +499,7 @@ proc run-gcov { args } {
>>>      set gcov_args ""
>>>      set gcov_verify_calls 0
>>>      set gcov_verify_branches 0
>>> +    set gcov_verify_conditions 0
>>>      set gcov_verify_lines 1
>>>      set gcov_verify_intermediate 0
>>>      set gcov_remove_gcda 0
>>> @@ -331,10 +510,13 @@ proc run-gcov { args } {
>>>  	  set gcov_verify_calls 1
>>>  	} elseif { $a == "branches" } {
>>>  	  set gcov_verify_branches 1
>>> +	} elseif { $a == "conditions" } {
>>> +	  set gcov_verify_conditions 1
>>>  	} 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
>>>  	} elseif { $a == "remove-gcda" } {
>>>  	  set gcov_remove_gcda 1
>>> @@ -404,6 +586,11 @@ proc run-gcov { args } {
>>>      } else {
>>>  	set bfailed 0
>>>      }
>>> +    if { $gcov_verify_conditions } {
>>> +	set cdfailed [verify-conditions $testname $testcase $testcase.gcov]
>>> +    } else {
>>> +	set cdfailed 0
>>> +    }
>>>      if { $gcov_verify_calls } {
>>>  	set cfailed [verify-calls $testname $testcase $testcase.gcov]
>>>      } else {
>>> @@ -418,12 +605,12 @@ proc run-gcov { args } {
>>>  
>>>      # Report whether the gcov test passed or failed.  If there were
>>>      # multiple failures then the message is a summary.
>>> -    set tfailed [expr $lfailed + $bfailed + $cfailed + $ifailed]
>>> +    set tfailed [expr $lfailed + $bfailed + $cdfailed + $cfailed + $ifailed]
>>>      if { $xfailed } {
>>>  	setup_xfail "*-*-*"
>>>      }
>>>      if { $tfailed > 0 } {
>>> -	fail "$testname gcov: $lfailed failures in line counts, $bfailed in branch percentages, $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"
>>>  	if { $xfailed } {
>>>  	    clean-gcov $testcase
>>>  	}
>>> diff --git a/gcc/tree-profile.cc b/gcc/tree-profile.cc
>>> index 2beb49241f2..0b537d64d97 100644
>>> --- a/gcc/tree-profile.cc
>>> +++ b/gcc/tree-profile.cc
>>> @@ -58,6 +58,8 @@ along with GCC; see the file COPYING3.  If not see
>>>  #include "alloc-pool.h"
>>>  #include "symbol-summary.h"
>>>  #include "symtab-thunks.h"
>>> +#include "cfganal.h"
>>> +#include "cfgloop.h"
>>>  
>>>  static GTY(()) tree gcov_type_node;
>>>  static GTY(()) tree tree_interval_profiler_fn;
>>> @@ -73,6 +75,1048 @@ static GTY(()) tree ic_tuple_var;
>>>  static GTY(()) tree ic_tuple_counters_field;
>>>  static GTY(()) tree ic_tuple_callee_field;
>>>  
>>> +namespace
>>> +{
>>> +/* Some context and reused instances between function calls.  Large embedded
>>> +   buffers are used to up-front request enough memory for most programs and
>>> +   merge them into a single allocation at the cost of using more memory in the
>>> +   average case.  Some numbers from linux v5.13 which is assumed to be a
>>> +   reasonably diverse code base: 75% of the functions in linux have less than
>>> +   16 nodes in the CFG and approx 2.5% have more than 64 nodes.  The functions
>>> +   that go beyond a few dozen nodes tend to be very large (>100) and so 64
>>> +   seems like a good balance.
>>> +
>>> +   This is really just a performance balance of the cost of allocation and
>>> +   wasted memory. */
>>> +struct conds_ctx
>>> +{
>>> +    /* Bitmap of the processed blocks.  Bit n set means basic_block->index has
>>> +       been processed either explicitly or as a part of an expression. */
>>> +    auto_sbitmap marks;
>>> +
>>> +    /* This is both a reusable shared allocation which is also used to return
>>> +       single expressions, which means it for most code should only hold a
>>> +       couple of elements. */
>>> +    auto_vec<basic_block, 32> blocks;
>>> +
>>> +    /* Map from basic_block->index to an ordering so that for a single
>>> +       expression (a || b && c) => index_map[a] < index_map[b] < index_map[c].
>>> +       The values do not have to be consecutive and can be interleaved by
>>> +       values from other expressions, so comparisons only make sense for blocks
>>> +       that belong to the same expression. */
>>> +    auto_vec<int, 64> index_map;
>>> +
>>> +    /* Pre-allocate bitmaps and vectors for per-function book keeping.  This is
>>> +       pure instance reuse and the bitmaps carry no data between function
>>> +       calls. */
>>> +    auto_vec<basic_block, 64> B1;
>>> +    auto_vec<basic_block, 64> B2;
>>> +    auto_sbitmap G1;
>>> +    auto_sbitmap G2;
>>> +    auto_sbitmap G3;
>>> +
>>> +    explicit conds_ctx (unsigned size) noexcept (true) : marks (size),
>>> +    G1 (size), G2 (size), G3 (size)
>>> +    {
>>> +	bitmap_clear (marks);
>>> +    }
>>> +
>>> +    /* Mark a node as processed so nodes are not processed twice for example in
>>> +       loops, gotos. */
>>> +    void mark (const basic_block b) noexcept (true)
>>> +    {
>>> +	gcc_assert (!bitmap_bit_p (marks, b->index));
>>> +	bitmap_set_bit (marks, b->index);
>>> +    }
>>> +
>>> +    /* Mark nodes as processed so they are not processed twice. */
>>> +    void mark (const vec<basic_block>& bs) noexcept (true)
>>> +    {
>>> +	for (const basic_block b : bs)
>>> +	    mark (b);
>>> +    }
>>> +
>>> +    /* Check if all nodes are marked.  A successful run should visit & mark
>>> +       every reachable node exactly once. */
>>> +    bool all_marked (const vec<basic_block>& reachable) const noexcept (true)
>>> +    {
>>> +	for (const basic_block b : reachable)
>>> +	    if (!bitmap_bit_p (marks, b->index))
>>> +		return false;
>>> +	return true;
>>> +    }
>>> +};
>>> +
>>> +/* Only instrument terms with fewer than number of bits in a (wide) gcov
>>> +   integer, which is probably 64.  The algorithm itself does not impose this
>>> +   limitation, but it makes for a simpler implementation.
>>> +
>>> +   * Allocating the output data structure (coverage_counter_alloc ()) can
>>> +     assume pairs of gcov_type_unsigned and not use a separate length field.
>>> +   * A pair gcov_type_unsigned can be used as accumulators.
>>> +   * Updating accumulators is can use the bitwise operations |=, &= and not
>>> +     custom operators that work for arbitrary-sized bit-sets.
>>> +
>>> +   Most real-world code should be unaffected by this, but it is possible
>>> +   (especially for generated code) to exceed this limit.
>>> + */
>>> +#define CONDITIONS_MAX_TERMS (sizeof (gcov_type_unsigned) * BITS_PER_UNIT)
>>> +#define EDGE_CONDITION (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)
>>> +
>>> +/* Compare two basic blocks by their order in the expression i.e. for (a || b)
>>> +   then cmp_index_map (a, b, ...) < 0.  The result is undefined if lhs, rhs
>>> +   belong to different expressions. */
>>> +int
>>> +cmp_index_map (const void *lhs, const void *rhs, void *index_map)
>>> +{
>>> +    const_basic_block l = *(const basic_block*) lhs;
>>> +    const_basic_block r = *(const basic_block*) rhs;
>>> +    const vec<int>* im = (const vec<int>*) index_map;
>>> +    return (*im)[l->index] - (*im)[r->index];
>>> +}
>>> +
>>> +/* Find the index of needle in blocks; return -1 if not found. This has two
>>> +   uses, sometimes for the index and sometimes for set member checks.  Sets are
>>> +   typically very small (number of conditions, >8 is uncommon) so linear search
>>> +   should be very fast. */
>>> +int
>>> +index_of (const basic_block needle, array_slice<basic_block> blocks)
>>> +{
>>> +    for (size_t i = 0; i < blocks.size (); i++)
>>> +	if (blocks[i] == needle)
>>> +	    return int (i);
>>> +    return -1;
>>> +}
>>> +
>>> +/* Returns true if this is a conditional node, i.e. it has outgoing true and
>>> +   false edges. */
>>> +bool
>>> +block_conditional_p (const basic_block b)
>>> +{
>>> +    unsigned t = 0;
>>> +    unsigned f = 0;
>>> +    for (edge e : b->succs)
>>> +    {
>>> +	t |= (e->flags & EDGE_TRUE_VALUE);
>>> +	f |= (e->flags & EDGE_FALSE_VALUE);
>>> +    }
>>> +    return t && f;
>>> +}
>>> +
>>> +/* Check if the edge is a conditional. */
>>> +bool
>>> +edge_conditional_p (const edge e)
>>> +{
>>> +    return e->flags & EDGE_CONDITION;
>>> +}
>>> +
>>> +/* Special cases of the single_*_p and single_*_edge functions in basic-block.h
>>> +   that don't consider exception handling or other complex edges.  This helps
>>> +   create a view of the CFG with only normal edges - if a basic block has both
>>> +   an outgoing fallthrough and exceptional edge [1], it should be considered a
>>> +   single-successor.
>>> +
>>> +   [1] if this is not possible, these functions can be removed and replaced by
>>> +       their basic-block.h cousins. */
>>> +bool
>>> +single (const vec<edge, va_gc> *edges)
>>> +{
>>> +    int n = EDGE_COUNT (edges);
>>> +    if (n == 0)
>>> +	return false;
>>> +
>>> +    for (edge e : edges)
>>> +	if (e->flags & EDGE_COMPLEX)
>>> +	    n -= 1;
>>> +
>>> +    return n == 1;
>>> +}
>>> +
>>> +/* Get the single, non-complex edge.  Behavior is undefined edges have more
>>> +   than 1 non-complex edges. */
>>> +edge
>>> +single_edge (const vec<edge, va_gc> *edges)
>>> +{
>>> +    for (edge e : edges)
>>> +    {
>>> +	if (e->flags & EDGE_COMPLEX)
>>> +	    continue;
>>> +	return e;
>>> +    }
>>> +    return NULL;
>>> +}
>>> +
>>> +/* Sometimes, for example with function calls and C++ destructors, the CFG gets
>>> +   extra nodes that are essentially single-entry-single-exit in the middle of
>>> +   boolean expressions.  For example:
>>> +
>>> +      x || can_throw (y)
>>> +
>>> +               A
>>> +              /|
>>> +             / |
>>> +            B  |
>>> +            |  |
>>> +            C  |
>>> +           / \ |
>>> +          /   \|
>>> +         F     T
>>> +
>>> +   Without the extra node inserted by the function + exception it becomes a
>>> +   proper 2-term graph, not 2 single-term graphs.
>>> +
>>> +               A
>>> +              /|
>>> +             C |
>>> +            / \|
>>> +           F   T
>>> +
>>> +   contract_edge ignores the series of intermediate nodes and makes a virtual
>>> +   edge A -> C without having to construct a new simplified CFG explicitly.  It
>>> +   gets more complicated as non-conditional edges is how the body of the
>>> +   then/else blocks are separated from the boolean expression, so only edges
>>> +   that are inserted because of function calls in the expression itself must be
>>> +   merged.
>>> +
>>> +   Only chains of single-exit single-entry nodes that end with a condition
>>> +   should be contracted. */
>>> +edge
>>> +contract_edge (edge e)
>>> +{
>>> +    edge source = e;
>>> +    while (true)
>>> +    {
>>> +	basic_block dest = e->dest;
>>> +	if (!single (dest->preds))
>>> +	    return source;
>>> +	if (e->flags & EDGE_DFS_BACK)
>>> +	    return source;
>>> +	if (block_conditional_p (dest))
>>> +	    return e;
>>> +
>>> +	e = single_edge (dest->succs);
>>> +	if (!e)
>>> +	    return source;
>>> +    }
>>> +}
>>> +
>>> +/* This is the predecessor dual of contract_edge; it collapses the predecessor
>>> +   blocks between two operands in a boolean expression. */
>>> +edge
>>> +contract_edge_up (edge e)
>>> +{
>>> +    while (true)
>>> +    {
>>> +	basic_block src = e->src;
>>> +	if (edge_conditional_p (e))
>>> +	    return e;
>>> +	if (!single (src->preds))
>>> +	    return e;
>>> +	e = single_edge (src->preds);
>>> +    }
>>> +}
>>> +
>>> +/* "Undo" an edge split.  Sometimes the sink of a boolean expression will be
>>> +   split into multiple blocks to accurately track line coverage, for example
>>> +   when there is a goto-label at the top of the then/else block:
>>> +
>>> +    if (a && b)
>>> +    {
>>> +	l1:
>>> +	...
>>> +    }
>>> +    else
>>> +    {
>>> +	l2:
>>> +	...
>>> +    }
>>> +
>>> +    and the corresponding CFG where a1 and b1 are created in edge splits to the
>>> +    same destination (F):
>>> +
>>> +    a
>>> +    |\
>>> +    | a1
>>> +    b  \
>>> +    |\  |
>>> +    | b1|
>>> +    |  \|
>>> +    T   F
>>> +
>>> +    This function recognizes this shape and returns the "merges" the split
>>> +    outcome block by returning their common successor.  In all other cases it is
>>> +    the identity function.
>>> +*/
>>> +basic_block
>>> +merge_split_outcome (basic_block b)
>>> +{
>>> +    if (!single (b->succs))
>>> +	return b;
>>> +    if (!single (b->preds))
>>> +	return b;
>>> +
>>> +    const unsigned flag = single_edge (b->preds)->flags & EDGE_CONDITION;
>>> +    if (!flag)
>>> +	return b;
>>> +
>>> +    edge e = single_edge (b->succs);
>>> +    for (edge pred : e->dest->preds)
>>> +    {
>>> +	if (!single (pred->src->preds))
>>> +	    return b;
>>> +	if (!(single_edge (pred->src->preds)->flags & flag))
>>> +	    return b;
>>> +    }
>>> +    return e->dest;
>>> +}
>>> +
>>> +
>>> +/* Find the set {ancestors(p) intersect G} where ancestors is the recursive set
>>> +   of predecessors for p.  Limiting to the ancestors that are also in G (see
>>> +   cond_reachable_from) and by q is an optimization as ancestors outside G have
>>> +   no effect when isolating expressions.
>>> +
>>> +   dfs_enumerate_from () does not work as the filter function needs edge
>>> +   information and dfs_enumerate_from () only considers blocks. */
>>> +void
>>> +ancestors_of (basic_block p, basic_block q, const sbitmap G, sbitmap ancestors)
>>> +{
>>> +    if (!bitmap_bit_p (G, p->index))
>>> +	return;
>>> +
>>> +    bitmap_set_bit (ancestors, p->index);
>>> +    bitmap_set_bit (ancestors, q->index);
>>> +    if (p == q)
>>> +	return;
>>> +
>>> +    auto_vec<basic_block, 16> stack;
>>> +    stack.safe_push (p);
>>> +
>>> +    while (!stack.is_empty())
>>> +    {
>>> +	basic_block b = stack.pop ();
>>> +	if (single (b->preds))
>>> +	{
>>> +	    edge e = single_edge (b->preds);
>>> +	    e = contract_edge_up (e);
>>> +	    b = e->dest;
>>> +	}
>>> +
>>> +	for (edge e : b->preds)
>>> +	{
>>> +	    basic_block src = e->src;
>>> +	    if (bitmap_bit_p (ancestors, e->src->index))
>>> +		continue;
>>> +	    if (!bitmap_bit_p (G, e->src->index))
>>> +		continue;
>>> +	    bitmap_set_bit (ancestors, src->index);
>>> +	    stack.safe_push (src);
>>> +	}
>>> +    }
>>> +}
>>> +
>>> +/* A simple struct for storing/returning outcome block pairs.  Either both
>>> +   blocks are set or both are NULL. */
>>> +struct outcomes
>>> +{
>>> +    basic_block t = NULL;
>>> +    basic_block f = NULL;
>>> +
>>> +    operator bool () const noexcept (true)
>>> +    {
>>> +	return t && f;
>>> +    }
>>> +};
>>> +
>>> +/* Get the true/false successors of a basic block. If b is not a conditional
>>> +   block both edges are NULL. */
>>> +outcomes
>>> +conditional_succs (const basic_block b)
>>> +{
>>> +    outcomes c;
>>> +    for (edge e : b->succs)
>>> +    {
>>> +	if (e->flags & EDGE_TRUE_VALUE)
>>> +	    c.t = merge_split_outcome (e->dest);
>>> +	if (e->flags & EDGE_FALSE_VALUE)
>>> +	    c.f = merge_split_outcome (e->dest);
>>> +    }
>>> +
>>> +    gcc_assert ((c.t && c.f) || (!c.t && !c.f));
>>> +    return c;
>>> +}
>>> +
>>> +/* Get the index or offset of a conditional flag, 0 for true and 1 for false.
>>> +   These indices carry no semantics but must be consistent as they are used to
>>> +   index into data structures in code generation and gcov. */
>>> +unsigned
>>> +condition_index (unsigned flag)
>>> +{
>>> +    return (flag & EDGE_CONDITION) == EDGE_TRUE_VALUE ? 0 : 1;
>>> +}
>>> +
>>> +/* Compute the masking vector.
>>> +
>>> +   Masking and short circuiting are deeply connected - masking occurs when
>>> +   control flow reaches a state that is also reachable with short circuiting.
>>> +   In fact, masking corresponds to short circuiting in the CFG for the reversed
>>> +   expression.  This means we can find the limits, the last term in preceeding
>>> +   subexpressions, by following the edges that short circuit to the same
>>> +   outcome.
>>> +
>>> +   In the simplest case a || b:
>>> +
>>> +   a
>>> +   |\
>>> +   | b
>>> +   |/ \
>>> +   T   F
>>> +
>>> +   T has has multiple incoming edges and is the outcome of a short circuit,
>>> +   with top = a, bot = b.  The top node (a) is masked when the edge (b, T) is
>>> +   taken.
>>> +
>>> +   The names "top" and "bot" refer to a pair of nodes with a shared
>>> +   destination. The top is always the node corresponding to the left-most
>>> +   operand of the two it holds that index_map[top] < index_map[bot].
>>> +
>>> +   Now consider (a && b) || (c && d) and its masking vectors:
>>> +
>>> +   a
>>> +   |\
>>> +   b \
>>> +   |\|
>>> +   | c
>>> +   | |\
>>> +   | d \
>>> +   |/ \|
>>> +   T   F
>>> +
>>> +   a[0] = {}
>>> +   a[1] = {}
>>> +   b[0] = {a}
>>> +   b[1] = {}
>>> +   c[0] = {}
>>> +   c[1] = {}
>>> +   d[0] = {c}
>>> +   d[1] = {a,b}
>>> +
>>> +   Note that 0 and 1 are indices and not boolean values - a[0] is the index in
>>> +   the masking vector when a takes the true edge.
>>> +
>>> +   b[0] and d[0] are identical to the a || b example, and d[1] is the bot in
>>> +   the triangle [d, b] -> T.  b is the top node in the [d, b] relationship and
>>> +   last term in (a && b).  To find the other terms masked we use the fact that
>>> +   all nodes in an expression have outgoing edges to either the outcome or some
>>> +   other node in the expression.  The "bot" node is also the last term in a
>>> +   masked subexpression, so the problem becomes finding the subgraph where all
>>> +   paths end up in the successors to bot.
>>> +
>>> +   We find the terms by marking the outcomes (in this case c, T) and walk the
>>> +   predecessors starting at top (in this case b) and masking nodes when both
>>> +   successors are marked.
>>> +
>>> +   The masking vector is represented as two bitfields per term in the
>>> +   expression with the index corresponding to the term in the source
>>> +   expression.  a || b && c becomes the term vector [a b c] and the masking
>>> +   vectors [a[0] a[1] b[0] ...].  The kth bit of a masking vector is set if the
>>> +   the kth term is masked by taking the edge. */
>>> +void
>>> +masking_vectors (conds_ctx& ctx, array_slice<basic_block> blocks,
>>> +		 array_slice<gcov_type_unsigned> masks)
>>> +{
>>> +    gcc_assert (blocks.is_valid ());
>>> +    gcc_assert (!blocks.empty ());
>>> +    gcc_assert (masks.is_valid ());
>>> +
>>> +    sbitmap marks = ctx.G1;
>>> +    sbitmap expr = ctx.G2;
>>> +    vec<basic_block>& queue = ctx.B1;
>>> +    vec<basic_block>& body = ctx.B2;
>>> +    const vec<int>& index_map = ctx.index_map;
>>> +    bitmap_clear (expr);
>>> +
>>> +    for (const basic_block b : blocks)
>>> +	bitmap_set_bit (expr, b->index);
>>> +
>>> +    /* Set up for the iteration - include two outcome nodes in the traversal and
>>> +       ignore the leading term since it cannot mask anything.  The algorithm is
>>> +       not sensitive to the traversal order. */
>>> +    body.truncate (0);
>>> +    body.reserve (blocks.size () + 2);
>>> +    for (const basic_block b : blocks)
>>> +	body.quick_push (b);
>>> +
>>> +    outcomes out = conditional_succs (blocks.back ());
>>> +    body.quick_push (out.t);
>>> +    body.quick_push (out.f);
>>> +    body[0] = body.pop ();
>>> +
>>> +    for (const basic_block b : body)
>>> +    {
>>> +	for (edge e1 : b->preds)
>>> +	for (edge e2 : b->preds)
>>> +	{
>>> +	    const basic_block top = e1->src;
>>> +	    const basic_block bot = e2->src;
>>> +	    const unsigned cond = e1->flags & e2->flags & (EDGE_CONDITION);
>>> +
>>> +	    if (!cond)
>>> +		continue;
>>> +	    if (e1 == e2)
>>> +		continue;
>>> +	    if (!bitmap_bit_p (expr, top->index))
>>> +		continue;
>>> +	    if (!bitmap_bit_p (expr, bot->index))
>>> +		continue;
>>> +	    if (index_map[top->index] > index_map[bot->index])
>>> +		continue;
>>> +
>>> +	    outcomes out = conditional_succs (top);
>>> +	    gcc_assert (out);
>>> +	    bitmap_clear (marks);
>>> +	    bitmap_set_bit (marks, out.t->index);
>>> +	    bitmap_set_bit (marks, out.f->index);
>>> +	    queue.truncate (0);
>>> +	    queue.safe_push (top);
>>> +
>>> +	    // The edge bot -> outcome triggers the masking
>>> +	    const int m = 2*index_of (bot, blocks) + condition_index (cond);
>>> +	    while (!queue.is_empty())
>>> +	    {
>>> +		basic_block q = queue.pop ();
>>> +		/* q may have been processed & completed by being added to the
>>> +		   queue multiple times, so check that there is still work to
>>> +		   do before continuing. */
>>> +		if (bitmap_bit_p (marks, q->index))
>>> +		    continue;
>>> +
>>> +		outcomes succs = conditional_succs (q);
>>> +		if (!bitmap_bit_p (marks, succs.t->index))
>>> +		    continue;
>>> +		if (!bitmap_bit_p (marks, succs.f->index))
>>> +		    continue;
>>> +
>>> +		const int index = index_of (q, blocks);
>>> +		gcc_assert (index != -1);
>>> +		masks[m] |= gcov_type_unsigned (1) << index;
>>> +		bitmap_set_bit (marks, q->index);
>>> +
>>> +		for (edge e : q->preds)
>>> +		{
>>> +		    e = contract_edge_up (e);
>>> +		    if (!edge_conditional_p (e))
>>> +			continue;
>>> +		    if (e->flags & EDGE_DFS_BACK)
>>> +			continue;
>>> +		    if (bitmap_bit_p (marks, e->src->index))
>>> +			continue;
>>> +		    if (!bitmap_bit_p (expr, e->src->index))
>>> +			continue;
>>> +		    queue.safe_push (e->src);
>>> +		}
>>> +	    }
>>> +	}
>>> +    }
>>> +}
>>> +
>>> +/* Find the nodes reachable from p by following only (possibly contracted)
>>> +   condition edges dominated by p and ignore DFS back edges.  From a high level
>>> +   this is partitioning the CFG into subgraphs by removing all non-condition
>>> +   edges and selecting a single connected subgraph.  This creates a cut C = (G,
>>> +   G') where G is the returned explicitly by this function.
>>> +
>>> +   It is assumed that all paths from p go through q (q post-dominates p).  p
>>> +   must always be the first term in an expression and a condition node.
>>> +
>>> +   If |G| = 1 then this is a single term expression. If |G| > 1 then either
>>> +   this is a multi-term expression or the first block in the then/else block is
>>> +   a conditional expression as well.
>>> +
>>> +   Only nodes dominated by p is added - under optimization some blocks may be
>>> +   merged and multiple independent conditions may share the same outcome
>>> +   (making successors misidentified as a right operands), but true right-hand
>>> +   operands are always dominated by the first term.
>>> +
>>> +   The function outputs both a bitmap and a vector as both are useful to the
>>> +   caller. */
>>> +void
>>> +cond_reachable_from (basic_block p, basic_block q, sbitmap expr,
>>> +		     vec<basic_block>& out)
>>> +{
>>> +    out.safe_push (p);
>>> +    bitmap_set_bit (expr, p->index);
>>> +    for (unsigned pos = 0; pos < out.length (); pos++)
>>> +    {
>>> +	for (edge e : out[pos]->succs)
>>> +	{
>>> +	    basic_block dest = contract_edge (e)->dest;
>>> +	    if (dest == q)
>>> +		continue;
>>> +	    if (!dominated_by_p (CDI_DOMINATORS, dest, p))
>>> +		continue;
>>> +	    if (!block_conditional_p (dest))
>>> +		continue;
>>> +	    if (bitmap_bit_p (expr, dest->index))
>>> +		continue;
>>> +	    if (e->flags & EDGE_DFS_BACK)
>>> +		continue;
>>> +
>>> +	    bitmap_set_bit (expr, dest->index);
>>> +	    out.safe_push (dest);
>>> +	}
>>> +    }
>>> +}
>>> +
>>> +/* Find the neighborhood of the graph G = [blocks, blocks+n), the
>>> +   successors of nodes in G that are not also in G.  In the cut C = (G, G')
>>> +   these are the nodes in G' with incoming edges that cross the span. */
>>> +void
>>> +neighborhood (const vec<basic_block>& blocks, sbitmap G, vec<basic_block>& out)
>>> +{
>>> +    for (const basic_block b : blocks)
>>> +    {
>>> +	for (edge e : b->succs)
>>> +	{
>>> +	    basic_block dest = contract_edge (e)->dest;
>>> +	    if (bitmap_bit_p (G, dest->index))
>>> +		continue;
>>> +	    if (!out.contains (dest))
>>> +		out.safe_push (dest);
>>> +	}
>>> +    }
>>> +
>>> +    /* Fix the neighborhood by correcting edge splits to the outcome nodes. */
>>> +    for (unsigned i = 0; i != out.length (); i++)
>>> +    {
>>> +	basic_block prev = out[i];
>>> +	basic_block next = merge_split_outcome (prev);
>>> +	if (next->index != prev->index)
>>> +	{
>>> +	    bitmap_set_bit (G, prev->index);
>>> +	    out[i] = next;
>>> +	}
>>> +    }
>>> +}
>>> +
>>> +/* Find and isolate the expression starting at p.
>>> +
>>> +   Make a cut C = (G, G') following only condition edges.  G is a superset of
>>> +   the expression B, but the walk may include expressions from the then/else
>>> +   blocks if they start with conditions.  Only the subgraph B is the ancestor
>>> +   of *both* the then/else outcome, which means B is the intersection of the
>>> +   ancestors of the nodes in the neighborhood N(G). */
>>> +void
>>> +isolate_expression (conds_ctx &ctx, basic_block p, vec<basic_block>& out)
>>> +{
>>> +    sbitmap expr = ctx.G1;
>>> +    sbitmap reachable = ctx.G2;
>>> +    sbitmap ancestors = ctx.G3;
>>> +    bitmap_clear (expr);
>>> +    bitmap_clear (reachable);
>>> +
>>> +    vec<basic_block>& G = ctx.B1;
>>> +    vec<basic_block>& NG = ctx.B2;
>>> +    G.truncate (0);
>>> +    NG.truncate (0);
>>> +
>>> +    basic_block post = get_immediate_dominator (CDI_POST_DOMINATORS, p);
>>> +    cond_reachable_from (p, post, reachable, G);
>>> +    if (G.length () == 1)
>>> +    {
>>> +	out.safe_push (p);
>>> +	return;
>>> +    }
>>> +
>>> +    neighborhood (G, reachable, NG);
>>> +    bitmap_copy (expr, reachable);
>>> +
>>> +    for (const basic_block neighbor : NG)
>>> +    {
>>> +	bitmap_clear (ancestors);
>>> +	for (edge e : neighbor->preds)
>>> +	    ancestors_of (e->src, p, reachable, ancestors);
>>> +	bitmap_and (expr, expr, ancestors);
>>> +    }
>>> +
>>> +    for (const basic_block b : G)
>>> +	if (bitmap_bit_p (expr, b->index))
>>> +	    out.safe_push (b);
>>> +    out.sort (cmp_index_map, &ctx.index_map);
>>> +}
>>> +
>>> +/* Emit lhs = op1 <op> op2 on edges.  This emits non-atomic instructions and
>>> +   should only be used on the local accumulators. */
>>> +void
>>> +emit_bitwise_op (edge e, tree lhs, tree op1, tree_code op, tree op2)
>>> +{
>>> +    tree tmp;
>>> +    gassign *read;
>>> +    gassign *bitw;
>>> +    gimple *write;
>>> +
>>> +    tmp = make_temp_ssa_name (gcov_type_node, NULL, "__conditions_tmp");
>>> +    read = gimple_build_assign (tmp, op1);
>>> +    tmp = make_temp_ssa_name (gcov_type_node, NULL, "__conditions_tmp");
>>> +    bitw = gimple_build_assign (tmp, op, gimple_assign_lhs (read), op2);
>>> +    write = gimple_build_assign (lhs, gimple_assign_lhs (bitw));
>>> +
>>> +    gsi_insert_on_edge (e, read);
>>> +    gsi_insert_on_edge (e, bitw);
>>> +    gsi_insert_on_edge (e, write);
>>> +}
>>> +
>>> +/* Visitor for make_index_map. */
>>> +void
>>> +make_index_map_visit (basic_block b, vec<basic_block>& L, vec<int>& marks)
>>> +{
>>> +    if (marks[b->index])
>>> +	return;
>>> +
>>> +    for (edge e : b->succs)
>>> +	if (!(e->flags & EDGE_DFS_BACK))
>>> +	    make_index_map_visit (e->dest, L, marks);
>>> +
>>> +    marks[b->index] = 1;
>>> +    L.quick_push (b);
>>> +}
>>> +
>>> +/* Find a topological sorting of the blocks in a function so that left operands
>>> +   are before right operands including subexpressions.  Sorting on block index
>>> +   does not guarantee this property and the syntactical order of terms is very
>>> +   important to the condition coverage.  The sorting algorithm is from Cormen
>>> +   et al (2001) but with back-edges ignored and thus there is no need for
>>> +   temporary marks (for cycle detection).
>>> +
>>> +   It is important to select unvisited nodes in DFS order to ensure the
>>> +   roots/leading terms of boolean expressions are visited first (the other
>>> +   terms being covered by the recursive step), but the visiting order of
>>> +   individual boolean expressions carries no significance.
>>> +
>>> +   For the expression (a || (b && c) || d) the blocks should be [a b c d]. */
>>> +void
>>> +make_index_map (const vec<basic_block>& blocks, int max_index,
>>> +		vec<basic_block>& L, vec<int>& index_map)
>>> +{
>>> +    L.truncate (0);
>>> +    L.reserve (max_index);
>>> +
>>> +    /* Use of the output map as a temporary for tracking visited status. */
>>> +    index_map.truncate (0);
>>> +    index_map.safe_grow_cleared (max_index);
>>> +    for (const basic_block b : blocks)
>>> +	make_index_map_visit (b, L, index_map);
>>> +
>>> +    /* Insert canaries - if there are unreachable nodes (for example infinite
>>> +       loops) then the unreachable nodes should never be needed for comparison,
>>> +       and L.length () < max_index.  An index mapping should also never be
>>> +       recorded twice. */
>>> +    for (unsigned i = 0; i < index_map.length (); i++)
>>> +	index_map[i] = -1;
>>> +
>>> +    gcc_assert (blocks.length () == L.length ());
>>> +    L.reverse ();
>>> +    const unsigned nblocks = L.length ();
>>> +    for (unsigned i = 0; i < nblocks; i++)
>>> +    {
>>> +	gcc_assert (L[i]->index != -1);
>>> +	index_map[L[i]->index] = int (i);
>>> +    }
>>> +}
>>> +
>>> +/* Walk the CFG and collect conditionals.
>>> +
>>> +   1. Collect a candidate set G by walking from the root following all
>>> +      (contracted) condition edges.
>>> +   2. This creates a cut C = (G, G'); find the neighborhood N(G).
>>> +   3. For every node in N(G), follow the edges across the cut and collect all
>>> +      ancestors (that are also in G).
>>> +   4. The intersection of all these ancestor sets is the boolean expression B
>>> +      that starts in root.
>>> +
>>> +   Walking is not guaranteed to find nodes in the order of the expression, it
>>> +   might find (a || b) && c as [a c b], so the result must be sorted by the
>>> +   index map. */
>>> +const vec<basic_block>&
>>> +collect_conditions (conds_ctx& ctx, const basic_block block)
>>> +{
>>> +    vec<basic_block>& blocks = ctx.blocks;
>>> +    blocks.truncate (0);
>>> +
>>> +    if (bitmap_bit_p (ctx.marks, block->index))
>>> +	return blocks;
>>> +
>>> +    if (!block_conditional_p (block))
>>> +    {
>>> +	ctx.mark (block);
>>> +	return blocks;
>>> +    }
>>> +
>>> +    isolate_expression (ctx, block, blocks);
>>> +    ctx.mark (blocks);
>>> +
>>> +    if (blocks.length () > CONDITIONS_MAX_TERMS)
>>> +    {
>>> +	location_t loc = gimple_location (gsi_stmt (gsi_last_bb (block)));
>>> +	warning_at (loc, OPT_Wcoverage_too_many_conditions,
>>> +		    "Too many conditions (found %u); giving up coverage",
>>> +		    blocks.length ());
>>> +	blocks.truncate (0);
>>> +    }
>>> +    return blocks;
>>> +}
>>> +
>>> +/* Used for dfs_enumerate_from () to include all reachable nodes. */
>>> +bool
>>> +yes (const_basic_block, const void *)
>>> +{
>>> +    return true;
>>> +}
>>> +
>>> +}
>>> +
>>> +struct condcov {
>>> +    explicit condcov (unsigned nblocks) noexcept (true) : ctx (nblocks) {}
>>> +    auto_vec<int, 128> m_index;
>>> +    auto_vec<basic_block, 256> m_blocks;
>>> +    auto_vec<gcov_type_unsigned, 512> m_masks;
>>> +    conds_ctx ctx;
>>> +};
>>> +
>>> +unsigned
>>> +cov_length (const struct condcov* cov)
>>> +{
>>> +    if (cov->m_index.is_empty ())
>>> +	return 0;
>>> +    return cov->m_index.length () - 1;
>>> +}
>>> +
>>> +array_slice<basic_block>
>>> +cov_blocks (struct condcov* cov, unsigned n)
>>> +{
>>> +    if (n >= cov->m_index.length ())
>>> +	return array_slice<basic_block>::invalid ();
>>> +
>>> +    basic_block *begin = cov->m_blocks.begin () + cov->m_index[n];
>>> +    basic_block *end = cov->m_blocks.begin () + cov->m_index[n + 1];
>>> +    return array_slice<basic_block> (begin, end - begin);
>>> +}
>>> +
>>> +array_slice<gcov_type_unsigned>
>>> +cov_masks (struct condcov* cov, unsigned n)
>>> +{
>>> +    if (n >= cov->m_index.length ())
>>> +	return array_slice<gcov_type_unsigned>::invalid ();
>>> +
>>> +    gcov_type_unsigned *begin = cov->m_masks.begin () + 2*cov->m_index[n];
>>> +    gcov_type_unsigned *end = cov->m_masks.begin () + 2*cov->m_index[n + 1];
>>> +    return array_slice<gcov_type_unsigned> (begin, end - begin);
>>> +}
>>> +
>>> +void
>>> +cov_free (struct condcov* cov)
>>> +{
>>> +    delete cov;
>>> +}
>>> +
>>> +/* Condition coverage (MC/DC)
>>> +
>>> +   Algorithm
>>> +   ---------
>>> +   Whalen, Heimdahl, De Silva in "Efficient Test Coverage Measurement for
>>> +   MC/DC" describe an algorithm for modified condition/decision coverage based
>>> +   on AST analysis.  This algorithm analyses the control flow graph to analyze
>>> +   expressions and compute masking vectors, but is inspired by their marking
>>> +   functions for recording outcomes.  The individual phases are described in
>>> +   more detail closer to the implementation.
>>> +
>>> +   The CFG is traversed in DFS order.  It is important that the first basic
>>> +   block in an expression is the first one visited, but the order of
>>> +   independent expressions does not matter.  When the function terminates,
>>> +   every node in the dfs should have been processed and marked exactly once.
>>> +   If there are unreachable nodes they are ignored and not instrumented.
>>> +
>>> +   The CFG is broken up into segments between dominators.  This isn't strictly
>>> +   necessary, but since boolean expressions cannot cross dominators it makes
>>> +   for a nice way to introduce limits to searches.
>>> +
>>> +   The coverage only considers the positions, not the symbols, in a
>>> +   conditional, e.g. !A || (!B && A) is a 3-term conditional even though A
>>> +   appears twice.  Subexpressions have no effect on term ordering:
>>> +   (a && (b || (c && d)) || e) comes out as [a b c d e].
>>> +
>>> +   The output for gcov is a vector of pairs of unsigned integers, interpreted
>>> +   as bit-sets, where the bit index corresponds to the index of the condition
>>> +   in the expression.
>>> + */
>>> +struct condcov*
>>> +find_conditions (struct function *fn)
>>> +{
>>> +    record_loop_exits ();
>>> +    mark_dfs_back_edges (fn);
>>> +
>>> +    const bool have_dom = dom_info_available_p (fn, CDI_DOMINATORS);
>>> +    const bool have_post_dom = dom_info_available_p (fn, CDI_POST_DOMINATORS);
>>> +    if (!have_dom)
>>> +	calculate_dominance_info (CDI_DOMINATORS);
>>> +    if (!have_post_dom)
>>> +	calculate_dominance_info (CDI_POST_DOMINATORS);
>>> +
>>> +    const unsigned nblocks = n_basic_blocks_for_fn (fn);
>>> +    condcov *cov = new condcov (nblocks);
>>> +    conds_ctx& ctx = cov->ctx;
>>> +
>>> +    auto_vec<basic_block, 16> dfs;
>>> +    dfs.safe_grow (nblocks);
>>> +    const basic_block entry = ENTRY_BLOCK_PTR_FOR_FN (fn);
>>> +    const basic_block exit = ENTRY_BLOCK_PTR_FOR_FN (fn);
>>> +    int n = dfs_enumerate_from (entry, 0, yes, dfs.address (), nblocks, exit);
>>> +    dfs.truncate (n);
>>> +    make_index_map (dfs, nblocks, ctx.B1, ctx.index_map);
>>> +
>>> +    /* Visit all reachable nodes and collect conditions.  DFS order is
>>> +       important so the first node of a boolean expression is visited first
>>> +       (it will mark subsequent terms). */
>>> +    cov->m_index.safe_push (0);
>>> +    for (const basic_block b : dfs)
>>> +    {
>>> +	const vec<basic_block>& expr = collect_conditions (ctx, b);
>>> +	if (!expr.is_empty ())
>>> +	{
>>> +	    cov->m_blocks.safe_splice (expr);
>>> +	    cov->m_index.safe_push (cov->m_blocks.length ());
>>> +	}
>>> +    }
>>> +    gcc_assert (ctx.all_marked (dfs));
>>> +
>>> +    if (!have_dom)
>>> +	free_dominance_info (fn, CDI_DOMINATORS);
>>> +    if (!have_post_dom)
>>> +	free_dominance_info (fn, CDI_POST_DOMINATORS);
>>> +
>>> +    cov->m_masks.safe_grow_cleared (2 * cov->m_index.last());
>>> +    const unsigned length = cov_length (cov);
>>> +    for (unsigned i = 0; i < length; i++)
>>> +	masking_vectors (ctx, cov_blocks (cov, i), cov_masks (cov, i));
>>> +
>>> +    return cov;
>>> +}
>>> +
>>> +int
>>> +instrument_decisions (array_slice<basic_block> expr, unsigned condno,
>>> +		      tree *accu, gcov_type_unsigned *masks)
>>> +{
>>> +    /* Zero the local accumulators. */
>>> +    tree zero = build_int_cst (get_gcov_type (), 0);
>>> +    for (edge e : expr[0]->succs)
>>> +    {
>>> +	gsi_insert_on_edge (e, gimple_build_assign (accu[0], zero));
>>> +	gsi_insert_on_edge (e, gimple_build_assign (accu[1], zero));
>>> +    }
>>> +    /* Add instructions for updating the function-local accumulators.  */
>>> +    for (size_t i = 0; i < expr.size (); i++)
>>> +    {
>>> +	for (edge e : expr[i]->succs)
>>> +	{
>>> +	    if (!edge_conditional_p (e))
>>> +		continue;
>>> +
>>> +	    /* accu |= expr[i] */
>>> +	    const int k = condition_index (e->flags);
>>> +	    tree rhs = build_int_cst (gcov_type_node, 1ULL << i);
>>> +	    emit_bitwise_op (e, accu[k], accu[k], BIT_IOR_EXPR, rhs);
>>> +
>>> +	    if (masks[2*i + k] == 0)
>>> +		continue;
>>> +
>>> +	    /* accu &= mask[i] */
>>> +	    tree mask = build_int_cst (gcov_type_node, ~masks[2*i + k]);
>>> +	    for (int j = 0; j < 2; j++)
>>> +		emit_bitwise_op (e, accu[j], accu[j], BIT_AND_EXPR, mask);
>>> +	}
>>> +    }
>>> +
>>> +    const bool atomic = flag_profile_update == PROFILE_UPDATE_ATOMIC;
>>> +    const tree atomic_ior = builtin_decl_explicit
>>> +	(TYPE_PRECISION (gcov_type_node) > 32
>>> +	 ? BUILT_IN_ATOMIC_FETCH_OR_8
>>> +	 : BUILT_IN_ATOMIC_FETCH_OR_4);
>>> +
>>> +    /* Add instructions for flushing the local accumulators.
>>> +
>>> +       It is important that the flushes happen on on the outcome's incoming
>>> +       edges, otherwise flushes could be lost to exception handling.
>>> +
>>> +       void fn (int a)
>>> +       {
>>> +	   if (a)
>>> +	    fclose();
>>> +	   exit();
>>> +       }
>>> +
>>> +       Can yield the CFG:
>>> +       A
>>> +       |\
>>> +       | B
>>> +       |/
>>> +       e
>>> +
>>> +       This typically only happen in optimized builds, but gives linker errors
>>> +       because the counter is left as an undefined symbol. */
>>> +
>>> +    outcomes out = conditional_succs (expr.back ());
>>> +    const basic_block outcome_blocks[] = { out.t, out.t, out.f, out.f, };
>>> +    const int outcome[] = { 0, 1, 0, 1 };
>>> +    for (int i = 0; i < 4; i++)
>>> +    {
>>> +	const int k = outcome[i];
>>> +	for (edge e : outcome_blocks[i]->preds)
>>> +	{
>>> +	    /* The outcome may have been split and we want to check if the
>>> +	       edge is sourced from inside the expression, so contract it to
>>> +	       find the source conditional edge. */
>>> +	    e = contract_edge_up (e);
>>> +
>>> +	    /* Only instrument edges from inside the expression. Sometimes
>>> +	       complicated control flow (like sigsetjmp and gotos) add
>>> +	       predecessors that don't come from the boolean expression. */
>>> +	    if (index_of (e->src, expr) == -1)
>>> +		continue;
>>> +
>>> +	    tree ref = tree_coverage_counter_ref (GCOV_COUNTER_CONDS,
>>> +						  2*condno + k);
>>> +	    tree tmp = make_temp_ssa_name (gcov_type_node, NULL,
>>> +					   "__conditions_tmp");
>>> +	    if (atomic)
>>> +	    {
>>> +		tree relaxed = build_int_cst (integer_type_node,
>>> +					      MEMMODEL_RELAXED);
>>> +		ref = unshare_expr (ref);
>>> +		gassign *read = gimple_build_assign (tmp, accu[k]);
>>> +		gcall *flush = gimple_build_call (atomic_ior, 3,
>>> +						  build_addr (ref),
>>> +						  gimple_assign_lhs (read),
>>> +						  relaxed);
>>> +
>>> +		gsi_insert_on_edge (e, read);
>>> +		gsi_insert_on_edge (e, flush);
>>> +	    }
>>> +	    else
>>> +	    {
>>> +		gassign *read = gimple_build_assign (tmp, ref);
>>> +		tmp = gimple_assign_lhs (read);
>>> +		gsi_insert_on_edge (e, read);
>>> +		ref = unshare_expr (ref);
>>> +		emit_bitwise_op (e, ref, accu[k], BIT_IOR_EXPR, tmp);
>>> +	    }
>>> +	}
>>> +    }
>>> +    return expr.size ();
>>> +}
>>> +
>>> +#undef CONDITIONS_MAX_TERMS
>>> +#undef EDGE_CONDITION
>>> +
>>>  /* Do initialization work for the edge profiler.  */
>>>  
>>>  /* Add code:
>>> @@ -758,7 +1802,7 @@ tree_profiling (void)
>>>  	  thunk = true;
>>>  	  /* When generate profile, expand thunk to gimple so it can be
>>>  	     instrumented same way as other functions.  */
>>> -	  if (profile_arc_flag)
>>> +	  if (profile_arc_flag || profile_condition_flag)
>>>  	    expand_thunk (node, false, true);
>>>  	  /* Read cgraph profile but keep function as thunk at profile-use
>>>  	     time.  */
>>> @@ -803,7 +1847,7 @@ tree_profiling (void)
>>>    release_profile_file_filtering ();
>>>  
>>>    /* Drop pure/const flags from instrumented functions.  */
>>> -  if (profile_arc_flag || flag_test_coverage)
>>> +  if (profile_arc_flag || profile_condition_flag || flag_test_coverage)
>>>      FOR_EACH_DEFINED_FUNCTION (node)
>>>        {
>>>  	if (!gimple_has_body_p (node->decl)
>>> @@ -897,7 +1941,7 @@ pass_ipa_tree_profile::gate (function *)
>>>       disabled.  */
>>>    return (!in_lto_p && !flag_auto_profile
>>>  	  && (flag_branch_probabilities || flag_test_coverage
>>> -	      || profile_arc_flag));
>>> +	      || profile_arc_flag || profile_condition_flag));
>>>  }
>>>  
>>>  } // anon namespace
>>> diff --git a/libgcc/libgcov-merge.c b/libgcc/libgcov-merge.c
>>> index 89741f637e1..9e3e8ee5657 100644
>>> --- a/libgcc/libgcov-merge.c
>>> +++ b/libgcc/libgcov-merge.c
>>> @@ -33,6 +33,11 @@ void __gcov_merge_add (gcov_type *counters  __attribute__ ((unused)),
>>>                         unsigned n_counters __attribute__ ((unused))) {}
>>>  #endif
>>>  
>>> +#ifdef L_gcov_merge_ior
>>> +void __gcov_merge_ior (gcov_type *counters  __attribute__ ((unused)),
>>> +		       unsigned n_counters __attribute__ ((unused))) {}
>>> +#endif
>>> +
>>>  #ifdef L_gcov_merge_topn
>>>  void __gcov_merge_topn (gcov_type *counters  __attribute__ ((unused)),
>>>  			unsigned n_counters __attribute__ ((unused))) {}
>>
>> Gentle ping. I have a tuned the summary output slightly (decisions covered ->
>> condition outcomes covered) already.
> 
> Ping. I would like to see this become a part of gcc 13, will we be able to
> commit before the window closes?
> 
> Thanks,
> Jørgen



  reply	other threads:[~2022-11-09 20:08 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-12 10:16 [PATCH] " Jørgen Kvalsvik
2022-10-18  0:17 ` Hans-Peter Nilsson
2022-10-18 10:13   ` Jørgen Kvalsvik
2022-10-25  6:33 ` Ping " Jørgen Kvalsvik
2022-10-27 10:34   ` Martin Liška
2022-11-02  6:16   ` Jørgen Kvalsvik
2022-11-09 20:08     ` Jørgen Kvalsvik [this message]
2022-11-10 14:19     ` Martin Liška

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