[libFuzzer] Diff 23 - Properly use compiler options supported on Windows.

[mpividori]

Summary

Replace "-g" by "-gline-tables-only". "-g" is not supported by clang-cl.

[kcc]

lib/Fuzzer/test/CMakeLists.txt

30

Nope. =edge should not be used any more with libFuzzer.
I am going to delete the libFuzzer code that supports it pretty soon.

What's wrong with trace-pc-guard,trace-cmp on windows?

37

hmmm. What is the 'else' compiler?

[zturner]

lib/Fuzzer/test/CMakeLists.txt

28

Technically we don't support MSVC, only clang-cl. So I would change this to if (CLANG_CL).

37

clang-cl I imagine, but /Z7 is more correct than /Zi. To make the else clear, you could say elseif(CLANG_CL)

[kcc]

lib/Fuzzer/test/CMakeLists.txt

37

Does clang-cl not support -g?

[mpividori]

lib/Fuzzer/test/CMakeLists.txt

28

@zturner, Yes, the only compiler in windows for this code is clang. I can use a more explicit flag.

30

@kcc Ok. I couldn't get that information from the documentation.
Trace-* options doesn't work on windows. I can try to fix them, I would need some time.

37

Yes, clang-cl doesn't support -g.

[kcc]

lib/Fuzzer/test/CMakeLists.txt

30

Ok. I couldn't get that information from the documentation.

Which documentation?
http://llvm.org/docs/LibFuzzer.html mentions only trace-pc-guard and trace-pc

Trace-* options doesn't work on windows. I can try to fix them, I would need some time.

What exactly is not working? (probably let's take it into another thread)

37

Sad, but ok.

[mpividori]

lib/Fuzzer/test/CMakeLists.txt

30

@kcc I refer to the Sanitizer Coverage documentation: http://clang.llvm.org/docs/SanitizerCoverage.html
It doesn't mention which options are supported on Windows.

[kcc]

lib/Fuzzer/test/CMakeLists.txt

30

Yep, because non of it is supported on windows (in terms of 'my team supporting them n windows').
But the trace- options don't have sanitizer-run-time portion when used with libFuzzer, so it's a pure compiler feature, nothing (??) OS-specific.
Except maybe the way how weak functions work... Hmmm. You will need to check this.

Anyway, libFuzzer will soon stop supporting anything but the options being used currently.

[mpividori]

Update diff to include suggested modifications.

[kcc]

please
a) update the change description.
b) find an analog for -g that works for both versions.
btw, we really only need -gmlt (= -gline-tables-only), so check if those work.

[kcc]

LGTM
Aha, that's much better (assuming tests pass on linux)

lib/Fuzzer/test/CMakeLists.txt

foreach (flag ${BUILD_FLAGS_AS_LIST})
     else()
       set(new_flags "${new_flags} -O0")
     endif()
   endforeach()
   set(${VARNAME} "${new_flags}")
 endforeach()
 
 # Enable the coverage instrumentation (it is disabled for the Fuzzer lib).
-set(CMAKE_CXX_FLAGS "${LIBFUZZER_FLAGS_BASE} -fsanitize-coverage=trace-pc-guard,indirect-calls,trace-cmp,trace-div,trace-gep -g")
+set(CMAKE_CXX_FLAGS "${LIBFUZZER_FLAGS_BASE} -fsanitize-coverage=trace-pc-guard,indirect-calls,trace-cmp,trace-div,trace-gep -gline-tables-only")
 
 # add_libfuzzer_test(<name>
 #   SOURCES source0.cpp [source1.cpp ...]
 #   )
 #
 #   Declares a LibFuzzer test executable with target name LLVMFuzzer-<name>.
 #
 #   One or more source files to be compiled into the binary must be declared
 #   after the SOURCES keyword.
 function(add_libfuzzer_test name)
   set(multi_arg_options "SOURCES")
   cmake_parse_arguments(
     "add_libfuzzer_test" "" "" "${multi_arg_options}" ${ARGN})
   if ("${add_libfuzzer_test_SOURCES}" STREQUAL "")
     message(FATAL_ERROR "Source files must be specified")
   endif()
   add_executable(LLVMFuzzer-${name}