Add '--filter mcdc' option - to remove MC/DC coverpoints which are

lib/lcovutil.pm

@@ -302,6 +302,8 @@ our $FILTER_MISSING_FILE;
 our $FILTER_EXCEPTION_BRANCH;
 # remove lone branch in block - it can't be an actual conditional
 our $FILTER_ORPHAN_BRANCH;
+# MC/DC with single expression is identical to branch
+our $FILTER_MCDC_SINGLE;
 our $FILTER_OMIT_PATTERNS;    # special/somewhat faked filter
 
 our %COVERAGE_FILTERS = ("branch"        => \$FILTER_BRANCH_NO_COND,
@@ -317,6 +319,7 @@ our %COVERAGE_FILTERS = ("branch"        => \$FILTER_BRANCH_NO_COND,
                          'branch_region' => \$FILTER_EXCLUDE_BRANCH,
                          'exception'     => \$FILTER_EXCEPTION_BRANCH,
                          'orphan'        => \$FILTER_ORPHAN_BRANCH,
+                         'mcdc'          => \$FILTER_MCDC_SINGLE,
                          "trivial"       => \$FILTER_TRIVIAL_FUNCTION,);
 our @cov_filter;    # 'undef' if filter is not enabled,
                     # [line_count, coverpoint_count] histogram if
@@ -2439,6 +2442,10 @@ sub parse_cov_filters(@)
             "branch filter enabled but neither branch or condition coverage is enabled"
         );
     }
+    lcovutil::ignorable_warning($ERROR_USAGE,
+                     "'mcdc' filter enabled but MC/DC coverage is not enabled.")
+        if (defined($cov_filter[$FILTER_MCDC_SINGLE]) &&
+            !$mcdc_coverage);
     if ($cov_filter[$FILTER_BRANCH_NO_COND]) {
         # turn on exception and orphan filtering too
         $cov_filter[$FILTER_EXCEPTION_BRANCH] = ['exception', 0, 0];
@@ -7429,6 +7436,8 @@ sub _filterFile
     my $directive = $cov_filter[$FILTER_DIRECTIVE];
     my $omit      = $cov_filter[$FILTER_OMIT_PATTERNS]
         if defined($FILTER_OMIT_PATTERNS);
+    my $mcdc_single = $cov_filter[$FILTER_MCDC_SINGLE]
+        if defined($FILTER_MCDC_SINGLE && $lcovutil::mcdc_coverage);
 
     my $context = MessageContext->new("filtering $source_file");
     if (lcovutil::is_filter_enabled()) {
@@ -7634,7 +7643,23 @@ sub _filterFile
                 }
             }    # foreach line
         }    # if branch_coverage
-             # Line related data
+        if ($mcdc_single) {
+            # find single-expression MC/DC's - if there is a matching branch
+            #  expression on the same line, then remove the MC/DC
+            foreach my $line ($mcdc_count->keylist()) {
+                my $block  = $mcdc_count->value($line);
+                my $groups = $block->groups();
+                if (exists($groups->{1}) &&
+                    scalar(keys %$groups) == 1) {
+                    my $branch = $testbrcount->value($line);
+                    next unless $branch && ($branch->totals())[0] == 2;
+                    $mcdc_count->remove($line);
+                    ++$mcdc_single->[-2];    # one MC/DC skipped
+
+                    $mcdc->remove($line);    # remove at top
+                }
+            }
+        }
         next
             unless $region    ||
             $range            ||
@@ -7644,6 +7669,7 @@ sub _filterFile
             $omit             ||
             $filter_initializer_list;
 
+        # Line related data
         my %initializerListRange;
         foreach my $line ($testcount->keylist()) {
             # don't suppresss if this line has associated branch or MC/DC data

man/genhtml.1

@@ -2236,6 +2236,13 @@ Exclude lines which appear to be part of a C++ std::initializer_list.
 alias for "\-\-filter brace,blank".
 .PP
 
+.IP mcdc: 3
+Remove MC/DC coverpoint which contains single expression, if 'branch' coverpoint
+is present on the same line.
+Singe-element MC/DC coverpoints are identical to the corresponding branch - except
+in the case of compile-time expression evaluation, for example, in a template
+function.
+
 .IP orphan: 3
 Remove branches which appear by themselves -
 .I i.e.,

tests/lcov/mcdc/main.cpp

@@ -21,4 +21,3 @@ int main(int ac, char ** av)
 #endif
   return 0;
 }
-

tests/lcov/mcdc/mcdc.sh

@@ -104,7 +104,7 @@ PARENT=`(cd .. ; pwd)`
 
 LCOV_OPTS="--branch-coverage $PARALLEL $PROFILE"
 
-rm -rf *.xml *.dat *.info *.jsn cover_one *_rpt *Test[123]*
+rm -rf *.xml *.dat *.info *.jsn cover_one *_rpt *Test[123]* *.gcno *.gcda gccTest* llvmTest*
 
 if [ "x$COVER" != "x" ] && [ $LOCAL_COVERAGE == 1 ]; then
     cover -delete
@@ -170,21 +170,25 @@ function runClang()
 
 function runGcc()
 {
+    NAME=$1
+    shift
+    ARG=$1
+    shift
     # runGcc exeName srcFile flags
-    g++ --coverage -fcondition-coverage -o $1 main.cpp test.cpp $2
+    eval g++ --coverage -fcondition-coverage -o $NAME main.cpp test.cpp $ARG
     if [ $? != 0 ] ; then
-        echo "ERROR from g++ $1"
+        echo "ERROR from g++ $NAME"
         return 1
     fi
-    ./$1
-    $COVER $GENINFO_TOOL -o $1.info --mcdc --branch $1-test.gcda
+    ./$NAME
+    $COVER $GENINFO_TOOL -o $NAME.info --mcdc --branch $NAME-test.gcda $@
     if [ $? != 0 ] ; then
-        echo "ERROR from geninfo $1"
+        echo "ERROR from geninfo $NAME"
         return 1
     fi
-    $COVER $GENHTML_TOOL --flat --branch --mcdc -o $1_rpt $1.info
+    $COVER $GENHTML_TOOL --flat --branch --mcdc -o ${NAME}_rpt $NAME.info
     if [ $? != 0 ] ; then
-        echo "ERROR from genhtml $1"
+        echo "ERROR from genhtml $NAME"
         return 1
     fi
     rm -f *.gcda *.gcno
@@ -232,6 +236,55 @@ if [ "$ENABLE_MCDC" == 1 ] ; then
             exit 1
         fi
     fi
+    runGcc gccTest4 '-DSENS2 -DSIMPLE' --filter mcdc
+    if [ $? != 0 ] ; then
+        STATUS=1
+        if [ $KEEP_GOING == 0 ] ; then
+            exit 1
+        fi
+    fi
+    # the MC/DC should have been filtered out - in favor of the branch
+    COUNT=`grep -c MCDC gccTest4.info`
+    if [ 0 != "$COUNT" ] ; then
+        STATUS=1
+        echo "filter error MC/DC"
+        if [ $KEEP_GOING == 0 ] ; then
+            exit 1
+        fi
+    fi
+    runGcc gccTest4a '-DSENS2 -DSIMPLE'
+    if [ $? != 0 ] ; then
+        STATUS=1
+        if [ $KEEP_GOING == 0 ] ; then
+            exit 1
+        fi
+    fi
+    # the MC/DC shouldn't be filtered
+    COUNT=`grep -c MCDC gccTest4a.info`
+    if [ 0 == "$COUNT" ] ; then
+        STATUS=1
+        echo "filter error2 MC/DC"
+        if [ $KEEP_GOING == 0 ] ; then
+            exit 1
+        fi
+    fi
+
+    runGcc gccTest5 -DSENS2 --filter mcdc
+    if [ $? != 0 ] ; then
+        STATUS=1
+        if [ $KEEP_GOING == 0 ] ; then
+            exit 1
+        fi
+    fi
+    # the MC/DC shouldn't have been filtered out
+    COUNT=`grep -c MCDC gccTest5.info`
+    if [ 0 == "$COUNT" ] ; then
+        STATUS=1
+        echo "MC/DC filter error"
+        if [ $KEEP_GOING == 0 ] ; then
+            exit 1
+        fi
+    fi
 else
     echo "SKIPPING MC/DC tests:  ancient compiler"
 fi
@@ -258,7 +311,7 @@ if [ "$ENABLE_LLVM" == 1 ] ; then
             exit 1
         fi
     fi
-else 
+else
     echo "SKIPPING LLVM tests"
 fi
 

tests/lcov/mcdc/test.cpp

@@ -8,9 +8,13 @@
 
 void test(int a, int b, int c)
 {
-  if (a && (b || c)) {
+  if
+#ifdef SIMPLE
+    (a)
+#else
+    (a && (b || c))
+#endif
     printf("%d && (%d || %d)\n", a, b, c);
-  } else {
+  else
     printf("not..\n");
-  }
 }