Update coverage options for fuzzing to match clang.

[pschuh]

Some of the sanitizer tests were crashing due to "-fsanitize-coverage=trace-pc-guard" which comes from setting "TracePCGuard" on Opts.SanitizeCoverage. I pulled the current options from clang.

[cheshire]

While we are there, could we also set OptForFuzzing?

[cheshire]

Otherwise LG

[pschuh]

Sorry, I don't see that here: https://llvm.org/doxygen/structllvm_1_1SanitizerCoverageOptions.html. I believe that needs to be set on each function.

[cheshire]

It's an LLVM codegen option. OK, adding it might be non-trivial, let's merge this as-is.

[cheshire]

@swift-ci please test

[cheshire]

@pschuh Why not merge this into master instead of master-next?

[pschuh]

Hmm, good question. Let me rebase.

[cheshire]

I'm not sure what LLVM version master and master-next are rev-locked into. Though if tests pass on master we should be good to go.

[pschuh]

I believe since it is based on master-next it'll run the master-next tests.

[pschuh]

@swift-ci please test

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 9e3be82a55ad713f52d89fa717d6e00187081fa8

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 9e3be82a55ad713f52d89fa717d6e00187081fa8

[pschuh]

@swift-ci please test

[pschuh]

@swift-ci please test macos

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 8ac72f6b0c45ea45e62a93e2da40d8f84173ee4f

[cheshire]

The error is:

20:08:27 Undefined symbols for architecture x86_64:
20:08:27   "___sancov_lowest_stack", referenced from:
20:08:27       _LLVMFuzzerTestOneInput in fuzzer_test_simpler-a995e3.o
20:08:27       _$s4main12fuzzOneInput4Data4Sizes5Int32VSPys4Int8VG_SitF in fuzzer_test_simpler-a995e3.o
20:08:27       _$sSPys4Int8VGMa in fuzzer_test_simpler-a995e3.o
20:08:27       _$sSPys4Int8VGSPyxGs8_PointersWl in fuzzer_test_simpler-a995e3.o
20:08:27 ld: symbol(s) not found for architecture x86_64

It seems you have forgotten to guard one of the options on "is linux" condition.

[pschuh]

@swift-ci please test macos

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 8ac72f6b0c45ea45e62a93e2da40d8f84173ee4f

[pschuh]

@swift-ci please test linux

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 8ac72f6b0c45ea45e62a93e2da40d8f84173ee4f

[cheshire]

Also please change the commit title to "Update coverage options for fuzzing to match clang"