Commit Graph

10569 Commits

Author SHA1 Message Date
Vlad Tsyrklevich a6446223e3 SafeStack: Disable Darwin support
Summary:
Darwin support does not appear to be used as evidenced by the fact that
the pthread interceptors have never worked and there is no support for
other common threading mechanisms like GCD.

Reviewers: pcc, eugenis, kubamracek

Reviewed By: pcc, kubamracek

Subscribers: kubamracek, mgorny, delcypher, llvm-commits, #sanitizers, kcc

Differential Revision: https://reviews.llvm.org/D50718

llvm-svn: 339719
2018-08-14 19:46:16 +00:00
Kostya Kortchinsky 3afc797e42 [scudo] Fix race condition in deallocation path when Quarantine is bypassed
Summary:
There is a race window in the deallocation path when the Quarantine is bypassed.
Initially we would just erase the header of a chunk if we were not to use the
Quarantine, as opposed to using a compare-exchange primitive, to make things
faster.

It turned out to be a poor decision, as 2 threads (or more) could simultaneously
deallocate the same pointer, and if the checks were to done before the header
got erased, this would result in the pointer being added twice (or more) to
distinct thread caches, and eventually be reused.

Winning the race is not trivial but can happen with enough control over the
allocation primitives. The repro added attempts to trigger the bug, with a
moderate success rate, but it should be enough to notice if the bug ever make
its way back into the code.

Since I am changing things in this file, there are 2 smaller changes tagging
along, marking a variable `const`, and improving the Quarantine bypass test at
runtime.

Reviewers: alekseyshl, eugenis, kcc, vitalybuka

Reviewed By: eugenis, vitalybuka

Subscribers: delcypher, #sanitizers, llvm-commits

Differential Revision: https://reviews.llvm.org/D50655

llvm-svn: 339705
2018-08-14 18:34:52 +00:00
Petr Hosek 39f0860743 [CMake] Don't parse target triple except for arch
compiler-rt CMake build currently tries to parse the triple and then
put it back together, but doing so inherently tricky, and doing so
from CMake is just crazy and currently doesn't handle triples that
have more than three components. Fortunatelly, the CMake really only
needs the architecture part, which is typically the first component,
to construct variants for other architectures. This means we can keep
the rest of the triple as is and avoid the parsing altogether.

Differential Revision: https://reviews.llvm.org/D50548

llvm-svn: 339701
2018-08-14 18:01:19 +00:00
Evgeniy Stepanov d8cc7f9f07 [hwasan] Provide __sanitizer_* aliases to allocator functions.
Summary:
Export __sanitizer_malloc, etc as aliases to malloc, etc.
This way users can wrap sanitizer malloc, even in fully static binaries.

Both jemalloc and tcmalloc provide similar aliases (je_* and tc_*).

Reviewers: vitalybuka, kcc

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D50570

llvm-svn: 339614
2018-08-13 21:07:27 +00:00
Evgeniy Stepanov 753bc5496b [hwasan] Handle missing /proc/self/maps.
Summary:
Don't crash when /proc/self/maps is inaccessible from main thread.
It's not a big deal, really.

Reviewers: vitalybuka, kcc

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D50574

llvm-svn: 339607
2018-08-13 20:04:48 +00:00
Evgeniy Stepanov c68be8d2d5 [hwasan] Allow optional early shadow setup.
Summary:
Provide __hwasan_shadow_init that can be used to initialize shadow w/o touching libc.
It can be used to bootstrap an unusual case of fully-static executable with
hwasan-instrumented libc, which needs to run hwasan code before it is ready to serve
user calls like madvise().

Reviewers: vitalybuka, kcc

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D50581

llvm-svn: 339606
2018-08-13 19:57:11 +00:00
Kostya Kortchinsky 15acf26c5d [sanitizer] Remove st(X) from the clobber list in 32-bit x86 atomics
Summary:
When compiling with `WERROR=ON` & a recent clang, having the `st(?)` registers
in the clobber list produces a fatal error (except `st(7)` for some reason):
```
.../sanitizer_common/sanitizer_atomic_clang_x86.h:98:9: error: inline asm clobber list contains reserved registers: ST0, ST1, ST2, ST3, ST4, ST5, ST6 [-Werror,-Winline-asm]
        "movq %1, %%mm0;"  // Use mmx reg for 64-bit atomic moves
        ^
<inline asm>:1:1: note: instantiated into assembly here
        movq 8(%esp), %mm0;movq %mm0, (%esi);emms;
^
.../sanitizer_common/sanitizer_atomic_clang_x86.h:98:9: note: Reserved registers on the clobber list may not be preserved across the asm statement, and clobbering them may lead to undefined behaviour.
        "movq %1, %%mm0;"  // Use mmx reg for 64-bit atomic moves
        ^
<inline asm>:1:1: note: instantiated into assembly here
        movq 8(%esp), %mm0;movq %mm0, (%esi);emms;
^
```
As far as I can tell, they were in there due to the use of the `emms`
instruction, but removing the clobber doesn't appear to have a functional
impact. I am unsure if there is a better way to address this.

Reviewers: eugenis, vitalybuka

Reviewed By: vitalybuka

Subscribers: kubamracek, delcypher, jfb, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D50562

llvm-svn: 339575
2018-08-13 15:01:24 +00:00
Dan Liew 706005486f [CMake] Fix bug in `add_weak_symbols()` function.
Previously the the `weak_symbols.txt` files could be modified and the
build system wouldn't update the link flags automatically. Instead the
developer had to know to reconfigure CMake manually.

This is now fixed by telling CMake that the file being used to
read weak symbols from is a configure-time dependency.

Differential Revision: https://reviews.llvm.org/D50059

llvm-svn: 339559
2018-08-13 12:59:38 +00:00
Evgeniy Stepanov 2339dc2397 [hwasan] Remove liblog dependency.
HWASan will not run on older Android releases where we use
__android_log_write for logging.

This dependency is also harmful in the case when libc itself depends
on hwasan, because it creates a loop of
  libc -> hwasan -> liblog -> libc
which makes liblog vs libc initialization order undetermined.

Without liblog the loop is just
  libc -> hwasan -> libc
and any init order issues can be solved in hwasan.

llvm-svn: 339449
2018-08-10 16:38:57 +00:00
Vlad Tsyrklevich bd85115c6e Revert "SafeStack: Delay thread stack clean-up"
This reverts commit r339405, it's failing on Darwin buildbots because
it doesn't seem to have a tgkill/thr_kill2 interface. It has a
__pthread_kill() syscall, but that relies on having a handle to the
thread's port which is not equivalent to it's tid.

llvm-svn: 339408
2018-08-10 00:36:04 +00:00
Vlad Tsyrklevich a24ecc337f SafeStack: Delay thread stack clean-up
Summary:
glibc can call SafeStack instrumented code even after the last pthread
data destructor has run. Delay cleaning-up unsafe stacks for threads
until the thread is dead by having future threads clean-up prior threads
stacks.

Reviewers: pcc, eugenis

Reviewed By: eugenis

Subscribers: cryptoad, eugenis, kubamracek, delcypher, llvm-commits, #sanitizers, kcc

Differential Revision: https://reviews.llvm.org/D50406

llvm-svn: 339405
2018-08-09 22:56:41 +00:00
Kostya Kortchinsky d2214053a2 [sanitizer] Remove rsp from the clobber list in internal_clone
Summary:
When compiling with WERROR=ON, a new fatal warning started popping up recently
(due to -Werror,-Winline-asm):
```
.../lib/sanitizer_common/sanitizer_linux.cc:1214:24: error: inline asm clobber list contains reserved registers: RSP [-Werror,-Winline-asm]
                       "syscall\n"
                       ^
<inline asm>:1:1: note: instantiated into assembly here
        syscall
^
.../lib/sanitizer_common/sanitizer_linux.cc:1214:24: note: Reserved registers on the clobber list may not be preserved across the asm statement, and clobbering them may lead to undefined behaviour.
                       "syscall\n"
                       ^
<inline asm>:1:1: note: instantiated into assembly here
        syscall
^
```

Removing `rsp` from the clobber list makes the warning go away, and does not
appear to have a functional impact. If there is another way to solve this, let
me know.

Reviewers: eugenis, vitalybuka

Reviewed By: eugenis

Subscribers: kubamracek, delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D50519

llvm-svn: 339370
2018-08-09 20:01:11 +00:00
David Carlier 9d03a90f15 Enable getentropy for FreeBSD 12
As for Linux with its getrandom's syscall, giving the possibility to fill buffer with native call for good quality but falling back to /dev/urandom in worst case similarly.

Reviewers: vitalybuka, krytarowski

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D48804

llvm-svn: 339318
2018-08-09 08:11:48 +00:00
Petr Hosek eb46c95c3e [CMake] Use normalized Windows target triples
Changes the default Windows target triple returned by
GetHostTriple.cmake from the old environment names (which we wanted to
move away from) to newer, normalized ones. This also requires updating
all tests to use the new systems names in constraints.

Differential Revision: https://reviews.llvm.org/D47381

llvm-svn: 339307
2018-08-09 02:16:18 +00:00
George Karpenkov 67d858d5e4 [libFuzzer] Increase the iteration limit in shrink.test
After https://reviews.llvm.org/D48800, shrink.test started failing on
x86_64h architecture.
Looking into this, the optimization pass is too eager to unroll the loop
on x86_64h, possibly leading to worse coverage data.

Alternative solutions include not unrolling the loop when fuzzing, or
disabling this test on that architecture.

Differential Revision: https://reviews.llvm.org/D50484

llvm-svn: 339303
2018-08-09 00:41:22 +00:00
Alex Lorenz 9693e8baa3 [macOS] stop generating the libclang_rt.10.4.a library for macOS 10.4
The support for macOS 10.4 has been dropped by Xcode 10.

rdar://42876880

llvm-svn: 339277
2018-08-08 17:29:55 +00:00
Max Moroz cd02f3147b [libFuzzer] Optimize handle unstable checks by reducing iterations
Summary:
We only run the 3rd check if 2nd check finds unstable edges. 
3rd UpdateUnstableCounters is now merged with ApplyUnstableCounters to only run 1 iteration.

Patch by Kyungtak Woo (@kevinwkt).

Reviewers: Dor1s, metzman, morehouse

Reviewed By: Dor1s, morehouse

Subscribers: delcypher, #sanitizers, llvm-commits, kcc

Differential Revision: https://reviews.llvm.org/D50411

llvm-svn: 339249
2018-08-08 14:32:46 +00:00
Vedant Kumar 381e9d2386 [Coverage] Ignore 'unused' functions with non-zero execution counts
Frontends emit 'unused' coverage mapping records for functions which are
provably unused in a TU. These unused records contain a single counter
with CounterKind::Zero. However, a function may be unused in one TU and
used in another. When this happens, prefer the records with a full set
of counters instead of arbitrarily picking the first loaded record.

There is no impact on the single-TU case. In the multiple-TU case, this
resolves issues causing a function to appear unused when it's not.

Testing: check-{llvm,clang,compiler-rt}

rdar://42981322

llvm-svn: 339194
2018-08-07 22:25:36 +00:00
Max Moroz e03993e6c7 [libFuzzer] Disable print_unstable_stats.test for aarch64.
Summary:
Follow-up for https://reviews.llvm.org/D50264. Reported by testbots:
http://lab.llvm.org:8011/builders/clang-cmake-aarch64-full/builds/5592

Reviewers: morehouse, kevinwkt, metzman, javed.absar, Dor1s

Reviewed By: Dor1s

Subscribers: kristof.beyls, delcypher, #sanitizers, llvm-commits, kcc

Differential Revision: https://reviews.llvm.org/D50386

llvm-svn: 339143
2018-08-07 14:22:00 +00:00
Max Moroz 84a48271d4 [libFuzzer] Add unstable function printing to print_unstable_stats flag
Summary:
There may be cases in which a user wants to know which part of their code is unstable.
We use ObservedFuncs and UnstableCounters to print at exit which of the ObservedFunctions
are unstable under the -print_unstable_stats flag.

Patch by Kyungtak Woo (@kevinwkt).

Reviewers: Dor1s, metzman, morehouse

Reviewed By: Dor1s, metzman, morehouse

Subscribers: delcypher, #sanitizers, llvm-commits, kcc

Differential Revision: https://reviews.llvm.org/D50264

llvm-svn: 339081
2018-08-06 23:14:13 +00:00
Martin Storsjo d07bd75cb3 [CMake] Allow building builtins standalone out of tree without any llvm-config available
This is the same as libcxxabi/libcxx do.

Differential Revision: https://reviews.llvm.org/D50134

llvm-svn: 338818
2018-08-03 05:50:33 +00:00
Max Moroz 5a9baa330c [libFuzzer] Initial implementation of weighted mutation leveraging during runtime.
Summary:
Added functions that calculate stats while fuzz targets are running and give
mutations weight based on how much new coverage they provide, and choose better
performing mutations more often.

Patch by Kodé Williams (@kodewilliams).

Reviewers: Dor1s, metzman, morehouse

Reviewed By: Dor1s, morehouse

Subscribers: delcypher, kcc, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D49621

llvm-svn: 338776
2018-08-02 22:30:03 +00:00
Filipe Cabecinhas 440e96f2f7 Add header guard to asan_report.h
llvm-svn: 338700
2018-08-02 11:05:07 +00:00
Kostya Serebryany cedebd5940 [libFuzzer] use absolute distance in addition to the hamming distance in value profiling; our A/B testing have (somewhat weak) indication that this provides an additional signal for corpus expansion
llvm-svn: 338661
2018-08-02 00:24:49 +00:00
Kostya Serebryany a8d7bcdd71 Fix sizeof(struct pthread) in glibc 2.14.
Summary: Fixes: https://github.com/google/sanitizers/issues/966

Reviewers: kcc

Reviewed By: kcc

Subscribers: kubamracek

Differential Revision: https://reviews.llvm.org/D50131

llvm-svn: 338606
2018-08-01 18:29:51 +00:00
Filipe Cabecinhas e0fcc68a32 Add missing condition
llvm-svn: 338577
2018-08-01 15:30:14 +00:00
Filipe Cabecinhas a0d8359079 Test: Enable exceptions for test that needs it
llvm-svn: 338535
2018-08-01 13:20:38 +00:00
Marco Castelluccio 85ae51ed22 [gcov] Add test which uses fork
Test for https://bugs.llvm.org/show_bug.cgi?id=38180.

llvm-svn: 338500
2018-08-01 09:11:36 +00:00
Matt Davis 89e8af6d96 [compiler-rt] Add a routine to specify the mode used when creating profile dirs.
Summary:
This patch introduces `llvm_profile_set_dir_mode` and `llvm_profile_get_dir_mode` to
the compiler-rt profile API. 

Originally, profile data was placed into a directory that was created with a hard-coded
mode value of 0755 (for non-win32 builds).  In certain cases, it can be helpful to create
directories with a different mode other than 0755.  This patch introduces set/get
routines to allow users to specify a desired mode.  The default remains at 0755.

Reviewers: void, probinson

Reviewed By: probinson

Subscribers: probinson, dberris, cfe-commits

Differential Revision: https://reviews.llvm.org/D49953

llvm-svn: 338456
2018-07-31 23:37:24 +00:00
Marco Castelluccio ae43a27f9c [gcov] Add tests using switch, one with break clauses and one with fallthrough
llvm-svn: 338453
2018-07-31 23:26:50 +00:00
Dean Michael Berris f8d5969943 [XRay][compiler-rt] Update test to use similar structure
This is a follow-up to D50037.

llvm-svn: 338349
2018-07-31 04:47:37 +00:00
Dean Michael Berris 3bd20d4605 [XRay][compiler-rt] Profiling Mode: Include file header in buffers
Summary:
This change provides access to the file header even in the in-memory
buffer processing. This allows in-memory processing of the buffers to
also check the version, and the format, of the profile data.

Reviewers: eizan, kpw

Reviewed By: eizan

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D50037

llvm-svn: 338347
2018-07-31 04:16:54 +00:00
Reid Kleckner cae1b9fef2 Pacify sanitizer lint script that still does not run on Windows
llvm-svn: 338334
2018-07-31 00:08:26 +00:00
Reid Kleckner a5ed43c1c9 [asan/win] Use SRW locks to fix a race in BlockingMutex
Summary:
Before my change, BlockingMutex used Windows critial sections. Critical
sections can only be initialized by calling InitializeCriticalSection,
dynamically.

The primary sanitizer allocator expects to be able to reinterpret zero
initialized memory as a BlockingMutex and immediately lock it.
RegionInfo contains a mutex, and it placement new is never called for
it. These objects are accessed via:
  RegionInfo *GetRegionInfo(uptr class_id) const {
    DCHECK_LT(class_id, kNumClasses);
    RegionInfo *regions = reinterpret_cast<RegionInfo *>(SpaceEnd());
    return &regions[class_id];
  }
The memory comes from the OS without any other initialization.

For various reasons described in the comments, BlockingMutex::Lock would
check if the object appeared to be zero-initialized, and it would lazily
call the LinkerInitialized constructor to initialize the critical
section. This pattern is obviously racy, and the code had a bunch of
FIXMEs about it.

The best fix here is to use slim reader writer locks, which can start
out zero-initialized. They are available starting in Windows Vista. I
think it's safe to go ahead and use them today.

Reviewers: kcc, vitalybuka

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D49893

llvm-svn: 338331
2018-07-30 23:32:33 +00:00
Roman Lebedev f07c5a0e9c [NFC] Rename test/ubsan/TestCases/{ImplicitCast => ImplicitConversion}
Just to be consistent with the rest.
I should have done that in the commit itself, but the filepaths
is one thing i forgot to verify :S

llvm-svn: 338307
2018-07-30 21:11:34 +00:00
Roman Lebedev 0c234517fd [compiler-rt] integer-truncation-blacklist.c: XFAIL on android/ios
The Builder sanitizer-x86_64-linux-android is failing
starting with rL338287 / D48959.

It runs the tests via android_compile.py, so i'm not sure this
is actually *this* issue:
  https://code.google.com/p/address-sanitizer/issues/detail?id=316
but this seems oddly similar to the other XFAIL'ed cases...

Right now that seems to be the only failing builder,
so i *think* it makes sense to try to just blacklist it for now.

llvm-svn: 338296
2018-07-30 20:05:24 +00:00
Roman Lebedev eb4a9bc343 [compiler-rt][ubsan] Implicit Conversion Sanitizer - integer truncation - compiler-rt part
Summary:
This is a compiler-rt part.
The clang part is D48958.

See [[ https://bugs.llvm.org/show_bug.cgi?id=21530 | PR21530 ]], https://github.com/google/sanitizers/issues/940.

Reviewers: #sanitizers, samsonov, vsk, rsmith, pcc, eugenis, kcc, filcab

Reviewed By: #sanitizers, vsk, filcab

Subscribers: llvm-commits, eugenis, filcab, kubamracek, dberris, #sanitizers, regehr

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D48959

llvm-svn: 338287
2018-07-30 18:58:30 +00:00
Azharuddin Mohammed ec6bdf8d4f [cmake] [ARM] Exclude any VFP builtins if VFP is not supported
Summary:
rL325492 disables FPU features when using soft floating point
(-mfloat-abi=soft), which is used internally when building for arm. This causes
errors with builtins that utililize VFP instructions.

With this change we check if VFP is enabled (by checking if the preprocessor
macro __VFP_FP__ is defined), and exclude such builtins if it is not enabled.

Reviewers: rengolin, samsonov, compnerd, smeenai, javed.absar, peter.smith

Reviewed By: peter.smith

Subscribers: delcypher, peter.smith, mgorny, kristof.beyls, chrib, llvm-commits

Differential Revision: https://reviews.llvm.org/D47217

llvm-svn: 338284
2018-07-30 18:18:59 +00:00
Dean Michael Berris f1ceb0b376 [XRay][compiler-rt] FDR Mode: Use mmap instead of internal allocator
Summary:
This change moves FDR mode to use `internal_mmap(...)` from
sanitizer_common instead of the internal allocator interface. We're
doing this to sidestep the alignment issues we encounter with the
`InternalAlloc(...)` functions returning pointers that have some magic
bytes at the beginning.

XRay copies bytes into the buffer memory, and does not require the magic
bytes tracking the other sanitizers use when allocating/deallocating
buffers.

Reviewers: kpw, eizan

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49972

llvm-svn: 338228
2018-07-30 05:56:42 +00:00
Fangrui Song 8c40e40a85 [asan] Fix typo
llvm-svn: 338225
2018-07-30 00:25:16 +00:00
Fangrui Song c0ca8089a2 Fix Asan-i386-calls-Test AddressSanitizer.ShadowGapTest on FreeBSD
0x22000000 happens to be on the left of a heap allocation and the error
message is different (heap-buffer-overflow).
FreeBSD NetBSD have larger SHADOW_OFFSET (0x40000000) but let's try not
using #ifdef here.

llvm-svn: 338208
2018-07-28 23:41:50 +00:00
Jonas Hahnfeld a7c9fe3762 [test] Use printf instead of C++ iostream, NFC.
This test fails with libc++ when built with MemorySanitizer. This
is because we link to an uninstrumented version of the library
so msan detects a nested error when calling std::cout << "...".
This can be easily avoided by using good old printf.

Differential Revision: https://reviews.llvm.org/D49867

llvm-svn: 338053
2018-07-26 18:23:40 +00:00
Dmitry Vyukov 04f97cf2f0 [tsan] Fix gcc pedantic warning
Fix gcc (7.2.0) pedantic warning
warning: extra ‘;’ [-Wpedantic]

Author: jasonl220 (Jason Lovett)
Review: https://reviews.llvm.org/D49817
llvm-svn: 338023
2018-07-26 13:02:54 +00:00
Fangrui Song cb1107ed14 [sanitizer] Include signal.h instead of sys/signal.h
llvm-svn: 338004
2018-07-26 04:50:33 +00:00
Max Moroz f55b8c6e91 [libFuzzer] Disable handle-unstable.test for ARM and delete duplicated test file.
Summary:
This change should fix the failures mentioned in
https://reviews.llvm.org/D49684#1175245

Reviewers: kevinwkt, morehouse, metzman

Reviewed By: kevinwkt, morehouse

Subscribers: kristof.beyls, delcypher, chrib, #sanitizers, llvm-commits, kcc

Differential Revision: https://reviews.llvm.org/D49810

llvm-svn: 337949
2018-07-25 18:34:20 +00:00
Jeremy Morse 63c153edb2 [XRay tests] Don't filter test-critical calls
By default, xray filters events that takes less than 5uS from its log.
In this existing test, should printf complete very quickly this will
lead to test-critical function calls being filtered (i.e. print_parent_tid).
Given that we're not testing the filtering feature, disable it for this
test.

llvm-svn: 337929
2018-07-25 14:48:53 +00:00
David Carlier 62e06ff583 [Asan][Msan] Unit tests Disable some tests for FreeBSD
Reviewers: krytarowski

Reviewed By: krytarowski

Differential Revision: https://reviews.llvm.org/D49784

llvm-svn: 337913
2018-07-25 12:38:23 +00:00
Petr Hosek 47e5fcba57 [profile] Support profiling runtime on Fuchsia
This ports the profiling runtime on Fuchsia and enables the
instrumentation. Unlike on other platforms, Fuchsia doesn't use
files to dump the instrumentation data since on Fuchsia, filesystem
may not be accessible to the instrumented process. We instead use
the data sink to pass the profiling data to the system the same
sanitizer runtimes do.

Differential Revision: https://reviews.llvm.org/D47208

llvm-svn: 337881
2018-07-25 03:01:35 +00:00
Matt Morehouse 5377b5b275 [sanitizer] Update symbolizer test.
llvm-svn: 337872
2018-07-24 23:50:42 +00:00
Max Moroz 8db0befc6d [libFuzzer] Handle unstable edges by disregarding unstable edges
Summary:
Added a new mode within flag -handle_unstable for new unstable handling algorithm that does the following:
    When an edge is shown as unstable, copy to UnstableCounters the value 0.
    During ApplyUnstableCounters we copy back the value 0 to ModuleInline8bitCounters if the edge was unstable.

This way we would be ignoring completely features that were collected through non-determinism.
Unstable hits would be counted as if it never hit.

Reviewers: metzman, Dor1s, kcc, morehouse

Reviewed By: metzman, morehouse

Subscribers: delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D49684

llvm-svn: 337853
2018-07-24 21:02:44 +00:00