Merge branch 'feature/fastcov' into develop

Makefile

@@ -35,6 +35,7 @@ all:
 	@echo "check-fast - compile and execute test suite (skip long-running tests)"
 	@echo "clean - remove built files"
 	@echo "coverage - create coverage information with lcov"
+	@echo "coverage-fast - create coverage information with fastcov"
 	@echo "cppcheck - analyze code with cppcheck"
 	@echo "cpplint - analyze code with cpplint"
 	@echo "clang_tidy - analyze code with Clang-Tidy"
@@ -82,6 +83,14 @@ coverage:
 	cd build_coverage ; ninja lcov_html
 	open build_coverage/test/html/index.html
 
+coverage-fast:
+	rm -fr build_coverage
+	mkdir build_coverage
+	cd build_coverage ; CXX=$(COMPILER_DIR)/g++ cmake .. -GNinja -DJSON_Coverage=ON -DJSON_MultipleHeaders=ON
+	cd build_coverage ; ninja
+	cd build_coverage ; ctest -E '.*_default' -j10
+	cd build_coverage ; ninja fastcov_html
+	open build_coverage/test/html/index.html
 
 ##########################################################################
 # documentation tests

README.md

@@ -1281,9 +1281,11 @@ The library itself consists of a single header file licensed under the MIT licen
 - [**doctest**](https://github.com/onqtam/doctest) for the unit tests
 - [**Doozer**](https://doozer.io) for [continuous integration](https://doozer.io/nlohmann/json) on Linux (CentOS, Raspbian, Fedora)
 - [**Doxygen**](http://www.stack.nl/~dimitri/doxygen/) to generate [documentation](https://nlohmann.github.io/json/)
+- [**fastcov**](https://github.com/RPGillespie6/fastcov) to process coverage information
 - [**git-update-ghpages**](https://github.com/rstacruz/git-update-ghpages) to upload the documentation to gh-pages
 - [**GitHub Changelog Generator**](https://github.com/skywinder/github-changelog-generator) to generate the [ChangeLog](https://github.com/nlohmann/json/blob/develop/ChangeLog.md)
 - [**Google Benchmark**](https://github.com/google/benchmark) to implement the benchmarks
+- [**lcov**](http://ltp.sourceforge.net/coverage/lcov.php) to process coverage information and create a HTML view
 - [**libFuzzer**](http://llvm.org/docs/LibFuzzer.html) to implement fuzz testing for OSS-Fuzz
 - [**OSS-Fuzz**](https://github.com/google/oss-fuzz) for continuous fuzz testing of the library ([project repository](https://github.com/google/oss-fuzz/tree/master/projects/json))
 - [**Probot**](https://probot.github.io) for automating maintainer tasks such as closing stale issues, requesting missing information, or detecting toxic comments.

test/CMakeLists.txt

@@ -27,17 +27,17 @@ endif()
 
 if(JSON_Coverage)
     message(STATUS "Building test suite with coverage information")
-    #if(NOT "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-    #    message(FATAL_ERROR "JSON_Coverage requires GCC.")
-    #endif()
+    if(NOT "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+        message(FATAL_ERROR "JSON_Coverage requires GCC.")
+    endif()
 
     # enable profiling
     set(CMAKE_CXX_FLAGS "--coverage -g -O0 -fprofile-arcs -ftest-coverage")
 
     # from https://github.com/RWTH-HPC/CMake-codecov/blob/master/cmake/FindGcov.cmake
-    #get_filename_component(COMPILER_PATH "${CMAKE_CXX_COMPILER}" PATH)
-    #string(REGEX MATCH "^[0-9]+" GCC_VERSION "${CMAKE_CXX_COMPILER_VERSION}")
-    #find_program(GCOV_BIN NAMES gcov-${GCC_VERSION} gcov HINTS ${COMPILER_PATH})
+    get_filename_component(COMPILER_PATH "${CMAKE_CXX_COMPILER}" PATH)
+    string(REGEX MATCH "^[0-9]+" GCC_VERSION "${CMAKE_CXX_COMPILER_VERSION}")
+    find_program(GCOV_BIN NAMES gcov-${GCC_VERSION} gcov HINTS ${COMPILER_PATH})
 
     # collect all source files from the chosen include dir
     file(GLOB_RECURSE SOURCE_FILES ${NLOHMANN_JSON_INCLUDE_BUILD_DIR}*.hpp)
@@ -46,11 +46,18 @@ if(JSON_Coverage)
     # (filter script from https://stackoverflow.com/a/43726240/266378)
     add_custom_target(lcov_html
         COMMAND lcov --directory . --capture --output-file json.info --rc lcov_branch_coverage=1
-        COMMAND lcov -e json.info ${SOURCE_FILES} --output-file json.info.filtered --rc lcov_branch_coverage=1
+        COMMAND lcov -e json.info ${SOURCE_FILES} --output-file json.info.filtered --gcov-tool ${GCOV_BIN} --rc lcov_branch_coverage=1
         COMMAND ${CMAKE_SOURCE_DIR}/test/thirdparty/imapdl/filterbr.py json.info.filtered > json.info.filtered.noexcept
         COMMAND genhtml --title "JSON for Modern C++" --legend --demangle-cpp --output-directory html --show-details --branch-coverage json.info.filtered.noexcept
         COMMENT "Generating HTML report test/html/index.html"
     )
+
+    add_custom_target(fastcov_html
+        COMMAND ${CMAKE_SOURCE_DIR}/test/thirdparty/fastcov/fastcov.py --branch-coverage --lcov -o json.info --gcov ${GCOV_BIN} --compiler-directory ${CMAKE_BINARY_DIR} --source-files ${SOURCE_FILES}
+        COMMAND ${CMAKE_SOURCE_DIR}/test/thirdparty/imapdl/filterbr.py json.info > json.info.noexcept
+        COMMAND genhtml --title "JSON for Modern C++" --legend --demangle-cpp --output-directory html --show-details --branch-coverage json.info.noexcept
+        COMMENT "Generating HTML report test/html/index.html"
+    )
 endif()
 
 #############################################################################

test/thirdparty/fastcov/LICENSE

@@ -0,0 +1,21 @@
+The MIT License
+
+Copyright (c) 2018-2019 Bryan Gillespie
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

test/thirdparty/fastcov/README.md

@@ -0,0 +1,46 @@
+# fastcov
+A massively parallel gcov wrapper for generating intermediate coverage formats *fast*
+
+The goal of fastcov is to generate code coverage intermediate formats *as fast as possible* (ideally < 1 second), even for large projects with hundreds of gcda objects. The intermediate formats may then be consumed by a report generator such as lcov's genhtml, or a dedicated front end such as coveralls. fastcov was originally designed to be a drop-in replacement for lcov (application coverage only, not kernel coverage).
+
+Currently the only intermediate formats supported are gcov json format and lcov info format. Adding support for other formats should require just a few lines of python to transform gcov json format to the desired shape.
+
+In order to achieve the massive speed gains, a few constraints apply:
+
+1. GCC version >= 9.0.0
+
+These versions of GCOV have support for JSON intermediate format as well as streaming report data straight to stdout
+
+2. Object files must be either be built:
+
+- Using absolute paths for all `-I` flags passed to the compiler
+- Invoking the compiler from the same root directory
+
+If you use CMake, you are almost certainly satisfying the second constraint (unless you care about `ExternalProject` coverage).
+
+## Sample Usage:
+```bash
+$ cd build_dir
+$ fastcov.py --zerocounters
+$ <run unit tests>
+$ fastcov.py --exclude /usr/include --lcov -o report.info
+$ genhtml -o code_coverage report.info
+```
+
+## Legacy fastcov
+
+It is possible to reap most of the benefits of fastcov for GCC version < 9.0.0 and >= 7.1.0. However, there will be a *potential* header file loss of correctness.
+
+`fastcov_legacy.py` can be used with pre GCC-9 down to GCC 7.1.0 but with a few penalties due to gcov limitations. This is because running gcov in parallel generates .gcov header reports in parallel which overwrite each other. This isn't a problem unless your header files have actual logic (i.e. header only library) that you want to measure coverage for. Use the `-F` flag to specify which gcda files should not be run in parallel in order to capture accurate header file data just for those. I don't plan on supporting `fastcov_legacy.py` aside from basic bug fixes.
+
+## Benchmarks
+
+Anecdotal testing on my own projects indicate that fastcov is over 100x faster than lcov and over 30x faster than gcovr:
+
+Project Size: ~250 .gcda, ~500 .gcov generated by gcov
+
+Time to process all gcda and parse all gcov:
+
+- fastcov: ~700ms
+- lcov:    ~90s
+- gcovr:   ~30s

test/thirdparty/fastcov/fastcov.py

@@ -0,0 +1,372 @@
+#!/usr/bin/env python3
+"""
+    Author: Bryan Gillespie
+
+    A massively parallel gcov wrapper for generating intermediate coverage formats fast
+
+    The goal of fastcov is to generate code coverage intermediate formats as fast as possible
+    (ideally < 1 second), even for large projects with hundreds of gcda objects. The intermediate
+    formats may then be consumed by a report generator such as lcov's genhtml, or a dedicated front
+    end such as coveralls.
+
+    Sample Usage:
+        $ cd build_dir
+        $ ./fastcov.py --zerocounters
+        $ <run unit tests>
+        $ ./fastcov.py --exclude /usr/include test/ --lcov -o report.info
+        $ genhtml -o code_coverage report.info
+"""
+
+import re
+import os
+import sys
+import glob
+import json
+import time
+import argparse
+import threading
+import subprocess
+import multiprocessing
+
+MINIMUM_GCOV = (9,0,0)
+MINIMUM_CHUNK_SIZE = 5
+
+# Interesting metrics
+START_TIME = time.time()
+GCOVS_TOTAL = []
+GCOVS_SKIPPED = []
+
+def chunks(l, n):
+    """Yield successive n-sized chunks from l."""
+    for i in range(0, len(l), n):
+        yield l[i:i + n]
+
+def stopwatch():
+    """Return number of seconds since last time this was called"""
+    global START_TIME
+    end_time   = time.time()
+    delta      = end_time - START_TIME
+    START_TIME = end_time
+    return delta
+
+def parseVersionFromLine(version_str):
+    """Given a string containing a dotted integer version, parse out integers and return as tuple"""
+    version = re.search(r'(\d+\.\d+\.\d+)[^\.]', version_str)
+
+    if not version:
+        return (0,0,0)
+
+    return tuple(map(int, version.group(1).split(".")))
+
+def getGcovVersion(gcov):
+    p = subprocess.Popen([gcov, "-v"], stdout=subprocess.PIPE)
+    output = p.communicate()[0].decode('UTF-8')
+    p.wait()
+    return parseVersionFromLine(output.split("\n")[0])
+
+def removeFiles(files):
+    for file in files:
+        os.remove(file)
+
+def getFilteredGcdaFiles(gcda_files, exclude):
+    def excludeGcda(gcda):
+        for ex in exclude:
+            if ex in gcda:
+                return False
+        return True
+    return list(filter(excludeGcda, gcda_files))
+
+def getGcdaFiles(cwd, gcda_files):
+    if not gcda_files:
+        gcda_files = glob.glob(os.path.join(os.path.abspath(cwd), "**/*.gcda"), recursive=True)
+    return gcda_files
+
+def gcovWorker(cwd, gcov, files, chunk, gcov_filter_options, branch_coverage):
+    gcov_args = "-it"
+    if branch_coverage:
+        gcov_args += "b"
+
+    p = subprocess.Popen([gcov, gcov_args] + chunk, cwd=cwd, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
+    for line in iter(p.stdout.readline, b''):
+        intermediate_json = json.loads(line.decode(sys.stdout.encoding))
+        intermediate_json_files = processGcovs(cwd, intermediate_json["files"], gcov_filter_options)
+        for f in intermediate_json_files:
+            files.append(f) #thread safe, there might be a better way to do this though
+        GCOVS_TOTAL.append(len(intermediate_json["files"]))
+        GCOVS_SKIPPED.append(len(intermediate_json["files"])-len(intermediate_json_files))
+    p.wait()
+
+def processGcdas(cwd, gcov, jobs, gcda_files, gcov_filter_options, branch_coverage):
+    chunk_size = max(MINIMUM_CHUNK_SIZE, int(len(gcda_files) / jobs) + 1)
+
+    threads = []
+    intermediate_json_files = []
+    for chunk in chunks(gcda_files, chunk_size):
+        t = threading.Thread(target=gcovWorker, args=(cwd, gcov, intermediate_json_files, chunk, gcov_filter_options, branch_coverage))
+        threads.append(t)
+        t.start()
+
+    log("Spawned %d gcov threads, each processing at most %d gcda files" % (len(threads), chunk_size))
+    for t in threads:
+        t.join()
+
+    return intermediate_json_files
+
+def processGcov(cwd, gcov, files, gcov_filter_options):
+    # Add absolute path
+    gcov["file_abs"] = os.path.abspath(os.path.join(cwd, gcov["file"]))
+
+    # If explicit sources were passed, check for match
+    if gcov_filter_options["sources"]:
+        if gcov["file_abs"] in gcov_filter_options["sources"]:
+            files.append(gcov)
+        return
+
+    # Check include filter
+    if gcov_filter_options["include"]:
+        for ex in gcov_filter_options["include"]:
+            if ex in gcov["file"]:
+                files.append(gcov)
+                break
+        return
+
+    # Check exclude filter
+    for ex in gcov_filter_options["exclude"]:
+        if ex in gcov["file"]:
+            return
+
+    files.append(gcov)
+
+def processGcovs(cwd, gcov_files, gcov_filter_options):
+    files = []
+    for gcov in gcov_files:
+        processGcov(cwd, gcov, files, gcov_filter_options)
+    return files
+
+def dumpBranchCoverageToLcovInfo(f, branches):
+    branch_miss  = 0
+    for line_num, branch_counts in branches.items():
+        for i, count in enumerate(branch_counts):
+            #Branch (<line number>, <block number>, <branch number>, <taken>)
+            f.write("BRDA:%s,%d,%d,%d\n" % (line_num, int(i/2), i, count))
+            branch_miss += int(count == 0)
+    f.write("BRF:%d\n" % len(branches))                 #Branches Found
+    f.write("BRH:%d\n" % (len(branches) - branch_miss)) #Branches Hit
+
+def dumpToLcovInfo(fastcov_json, output):
+    with open(output, "w") as f:
+        for sf, data in fastcov_json["sources"].items():
+            f.write("SF:%s\n" % sf) #Source File
+
+            fn_miss = 0
+            for function, fdata in data["functions"].items():
+                f.write("FN:%d,%s\n" % (fdata["start_line"], function))          #Function Start Line
+                f.write("FNDA:%d,%s\n" % (fdata["execution_count"], function))   #Function Hits
+                fn_miss += int(fdata["execution_count"] == 0)
+            f.write("FNF:%d\n" % len(data["functions"]))                #Functions Found
+            f.write("FNH:%d\n" % (len(data["functions"]) - fn_miss))    #Functions Hit
+
+            if data["branches"]:
+                dumpBranchCoverageToLcovInfo(f, data["branches"])
+
+            line_miss = 0
+            for line_num, count in data["lines"].items():
+                f.write("DA:%s,%d\n" % (line_num, count)) #Line
+                line_miss += int(count == 0)
+            f.write("LF:%d\n" % len(data["lines"]))                 #Lines Found
+            f.write("LH:%d\n" % (len(data["lines"]) - line_miss))   #Lines Hit
+            f.write("end_of_record\n")
+
+def exclMarkerWorker(fastcov_sources, chunk):
+    for source in chunk:
+        # If there are no covered lines, skip
+        if not fastcov_sources[source]["lines"]:
+            continue
+
+        start_line = 0
+        end_line = 0
+        with open(source) as f:
+            for i, line in enumerate(f, 1): #Start enumeration at line 1
+                if not "LCOV_EXCL" in line:
+                    continue
+
+                if "LCOV_EXCL_LINE" in line:
+                    if str(i) in fastcov_sources[source]["lines"]:
+                        del fastcov_sources[source]["lines"][str(i)]
+                    if str(i) in fastcov_sources[source]["branches"]:
+                        del fastcov_sources[source]["branches"][str(i)]
+                elif "LCOV_EXCL_START" in line:
+                    start_line = i
+                elif "LCOV_EXCL_STOP" in line:
+                    end_line = i
+
+                    if not start_line:
+                        end_line = 0
+                        continue
+
+                    for key in ["lines", "branches"]:
+                        for line_num in list(fastcov_sources[source][key].keys()):
+                            if int(line_num) <= end_line and int(line_num) >= start_line:
+                                del fastcov_sources[source][key][line_num]
+
+                    start_line = end_line = 0
+
+def scanExclusionMarkers(fastcov_json, jobs):
+    chunk_size = max(MINIMUM_CHUNK_SIZE, int(len(fastcov_json["sources"]) / jobs) + 1)
+
+    threads = []
+    for chunk in chunks(list(fastcov_json["sources"].keys()), chunk_size):
+        t = threading.Thread(target=exclMarkerWorker, args=(fastcov_json["sources"], chunk))
+        threads.append(t)
+        t.start()
+
+    log("Spawned %d threads each scanning at most %d source files" % (len(threads), chunk_size))
+    for t in threads:
+        t.join()
+
+def distillFunction(function_raw, functions):
+    function_name = function_raw["name"]
+    if function_name not in functions:
+        functions[function_name] = {
+            "start_line": function_raw["start_line"],
+            "execution_count": function_raw["execution_count"]
+        }
+    else:
+        functions[function_name]["execution_count"] += function_raw["execution_count"]
+
+def distillLine(line_raw, lines, branches):
+    line_number = str(line_raw["line_number"])
+    if line_number not in lines:
+        lines[line_number] = line_raw["count"]
+    else:
+        lines[line_number] += line_raw["count"]
+
+    for i, branch in enumerate(line_raw["branches"]):
+        if line_number not in branches:
+            branches[line_number] = []
+        blen = len(branches[line_number])
+        glen = len(line_raw["branches"])
+        if blen < glen:
+            branches[line_number] += [0] * (glen - blen)
+        branches[line_number][i] += branch["count"]
+
+def distillSource(source_raw, sources):
+    source_name = source_raw["file_abs"]
+    if source_name not in sources:
+        sources[source_name] = {
+            "functions": {},
+            "branches": {},
+            "lines": {},
+        }
+
+    for function in source_raw["functions"]:
+        distillFunction(function, sources[source_name]["functions"])
+
+    for line in source_raw["lines"]:
+        distillLine(line, sources[source_name]["lines"], sources[source_name]["branches"])
+
+def distillReport(report_raw):
+    report_json = {
+        "sources": {}
+    }
+
+    for source in report_raw:
+        distillSource(source, report_json["sources"])
+
+    return report_json
+
+def dumpToJson(intermediate, output):
+    with open(output, "w") as f:
+        json.dump(intermediate, f)
+
+def log(line):
+    if not args.quiet:
+        print("[{:.3f}s] {}".format(stopwatch(), line))
+
+def getGcovFilterOptions(args):
+    return {
+        "sources": set([os.path.abspath(s) for s in args.sources]), #Make paths absolute, use set for fast lookups
+        "include": args.includepost,
+        "exclude": args.excludepost,
+    }
+
+def main(args):
+    # Need at least gcov 9.0.0 because that's when gcov JSON and stdout streaming was introduced
+    current_gcov_version = getGcovVersion(args.gcov)
+    if current_gcov_version < MINIMUM_GCOV:
+        sys.stderr.write("Minimum gcov version {} required, found {}\n".format(".".join(map(str, MINIMUM_GCOV)), ".".join(map(str, current_gcov_version))))
+        exit(1)
+
+    # Get list of gcda files to process
+    gcda_files = getGcdaFiles(args.directory, args.gcda_files)
+    log("Found {} .gcda files ".format(len(gcda_files)))
+
+    # If gcda filtering is enabled, filter them out now
+    if args.excludepre:
+        gcda_files = getFilteredGcdaFiles(gcda_files, args.excludepre)
+        log("{} .gcda files after filtering".format(len(gcda_files)))
+
+    # We "zero" the "counters" by simply deleting all gcda files
+    if args.zerocounters:
+        removeFiles(gcda_files)
+        log("{} .gcda files removed".format(len(gcda_files)))
+        return
+
+    # Fire up one gcov per cpu and start processing gcdas
+    gcov_filter_options = getGcovFilterOptions(args)
+    intermediate_json_files = processGcdas(args.cdirectory, args.gcov, args.jobs, gcda_files, gcov_filter_options, args.branchcoverage)
+
+    # Summarize processing results
+    gcov_total = sum(GCOVS_TOTAL)
+    gcov_skipped = sum(GCOVS_SKIPPED)
+    log("Processed {} .gcov files ({} total, {} skipped)".format(gcov_total - gcov_skipped, gcov_total, gcov_skipped))
+
+    # Distill all the extraneous info gcov gives us down to the core report
+    fastcov_json = distillReport(intermediate_json_files)
+    log("Aggregated raw gcov JSON into fastcov JSON report")
+
+    # Dump to desired file format
+    if args.lcov:
+        scanExclusionMarkers(fastcov_json, args.jobs)
+        log("Scanned {} source files for exclusion markers".format(len(fastcov_json["sources"])))
+        dumpToLcovInfo(fastcov_json, args.output)
+        log("Created lcov info file '{}'".format(args.output))
+    elif args.gcov_raw:
+        dumpToJson(intermediate_json_files, args.output)
+        log("Created gcov raw json file '{}'".format(args.output))
+    else:
+        dumpToJson(fastcov_json, args.output)
+        log("Created fastcov json file '{}'".format(args.output))
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='A parallel gcov wrapper for fast coverage report generation')
+    parser.add_argument('-z', '--zerocounters', dest='zerocounters', action="store_true", help='Recursively delete all gcda files')
+
+    # Enable Branch Coverage
+    parser.add_argument('-b', '--branch-coverage', dest='branchcoverage', action="store_true", help='Include branch counts in the coverage report')
+
+    # Filtering Options
+    parser.add_argument('-s', '--source-files', dest='sources',     nargs="+", metavar='', default=[], help='Filter: Specify exactly which source files should be included in the final report. Paths must be either absolute or relative to current directory.')
+    parser.add_argument('-e', '--exclude',      dest='excludepost', nargs="+", metavar='', default=[], help='Filter: Exclude source files from final report if they contain one of the provided substrings (i.e. /usr/include test/, etc.)')
+    parser.add_argument('-i', '--include',      dest='includepost', nargs="+", metavar='', default=[], help='Filter: Only include source files in final report that contain one of the provided substrings (i.e. src/ etc.)')
+    parser.add_argument('-f', '--gcda-files',   dest='gcda_files',  nargs="+", metavar='', default=[], help='Filter: Specify exactly which gcda files should be processed instead of recursively searching the search directory.')
+    parser.add_argument('-E', '--exclude-gcda', dest='excludepre',  nargs="+", metavar='', default=[], help='Filter: Exclude gcda files from being processed via simple find matching (not regex)')
+
+    parser.add_argument('-g', '--gcov', dest='gcov', default='gcov', help='Which gcov binary to use')
+
+    parser.add_argument('-d', '--search-directory', dest='directory', default=".", help='Base directory to recursively search for gcda files (default: .)')
+    parser.add_argument('-c', '--compiler-directory', dest='cdirectory', default=".", help='Base directory compiler was invoked from (default: .) \
+                                                                                            This needs to be set if invoking fastcov from somewhere other than the base compiler directory.')
+
+    parser.add_argument('-j', '--jobs', dest='jobs', type=int, default=multiprocessing.cpu_count(), help='Number of parallel gcov to spawn (default: %d).' % multiprocessing.cpu_count())
+    parser.add_argument('-m', '--minimum-chunk-size', dest='minimum_chunk', type=int, default=5, help='Minimum number of files a thread should process (default: 5). \
+                                                                                                       If you have only 4 gcda files but they are monstrously huge, you could change this value to a 1 so that each thread will only process 1 gcda. Otherise fastcov will spawn only 1 thread to process all of them.')
+
+    parser.add_argument('-l', '--lcov',     dest='lcov',     action="store_true", help='Output in lcov info format instead of fastcov json')
+    parser.add_argument('-r', '--gcov-raw', dest='gcov_raw', action="store_true", help='Output in gcov raw json instead of fastcov json')
+    parser.add_argument('-o', '--output',  dest='output', default="coverage.json", help='Name of output file (default: coverage.json)')
+    parser.add_argument('-q', '--quiet', dest='quiet', action="store_true", help='Suppress output to stdout')
+
+    args = parser.parse_args()
+    main(args)