Commit Graph

248 Commits

Author SHA1 Message Date
Vedant Kumar dd1ea9de2e Reland: [Coverage] Revise format to reduce binary size
Try again with an up-to-date version of D69471 (99317124 was a stale
revision).

---

Revise the coverage mapping format to reduce binary size by:

1. Naming function records and marking them `linkonce_odr`, and
2. Compressing filenames.

This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB)
and speeds up end-to-end single-threaded report generation by 10%. For
reference the compressed name data in llc is 81MB (__llvm_prf_names).

Rationale for changes to the format:

- With the current format, most coverage function records are discarded.
  E.g., more than 97% of the records in llc are *duplicate* placeholders
  for functions visible-but-not-used in TUs. Placeholders *are* used to
  show under-covered functions, but duplicate placeholders waste space.

- We reached general consensus about giving (1) a try at the 2017 code
  coverage BoF [1]. The thinking was that using `linkonce_odr` to merge
  duplicates is simpler than alternatives like teaching build systems
  about a coverage-aware database/module/etc on the side.

- Revising the format is expensive due to the backwards compatibility
  requirement, so we might as well compress filenames while we're at it.
  This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB).

See CoverageMappingFormat.rst for the details on what exactly has
changed.

Fixes PR34533 [2], hopefully.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html
[2] https://bugs.llvm.org/show_bug.cgi?id=34533

Differential Revision: https://reviews.llvm.org/D69471
2020-02-28 18:12:04 -08:00
Vedant Kumar 3388871714 Revert "[Coverage] Revise format to reduce binary size"
This reverts commit 99317124e1. This is
still busted on Windows:

http://lab.llvm.org:8011/builders/lld-x86_64-win7/builds/40873

The llvm-cov tests report 'error: Could not load coverage information'.
2020-02-28 18:03:15 -08:00
Vedant Kumar 99317124e1 [Coverage] Revise format to reduce binary size
Revise the coverage mapping format to reduce binary size by:

1. Naming function records and marking them `linkonce_odr`, and
2. Compressing filenames.

This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB)
and speeds up end-to-end single-threaded report generation by 10%. For
reference the compressed name data in llc is 81MB (__llvm_prf_names).

Rationale for changes to the format:

- With the current format, most coverage function records are discarded.
  E.g., more than 97% of the records in llc are *duplicate* placeholders
  for functions visible-but-not-used in TUs. Placeholders *are* used to
  show under-covered functions, but duplicate placeholders waste space.

- We reached general consensus about giving (1) a try at the 2017 code
  coverage BoF [1]. The thinking was that using `linkonce_odr` to merge
  duplicates is simpler than alternatives like teaching build systems
  about a coverage-aware database/module/etc on the side.

- Revising the format is expensive due to the backwards compatibility
  requirement, so we might as well compress filenames while we're at it.
  This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB).

See CoverageMappingFormat.rst for the details on what exactly has
changed.

Fixes PR34533 [2], hopefully.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html
[2] https://bugs.llvm.org/show_bug.cgi?id=34533

Differential Revision: https://reviews.llvm.org/D69471
2020-02-28 17:33:25 -08:00
Max Moroz 5517d3b80b [compiler-rt] Fix a typo in a comment in FuzzedDataProvider.h. 2020-02-25 17:10:16 -08:00
Max Moroz 20a604d3f5 [compiler-rt] FuzzedDataProvider: add ConsumeData and method.
Reviewers: metzman

Subscribers: dberris, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D74359
2020-02-11 13:46:24 -08:00
Evgenii Stepanov dd921cb89b [sanitizer] Add missing declarations for sigaltstack syscall wrappers.
Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D73987
2020-02-04 13:10:43 -08:00
Evgenii Stepanov 28c91219c7 [compiler-rt] implement sigaltstack interception
Summary:
An implementation for `sigaltstack` to make its side effect be visible to MSAN.

```
ninja check-msan
```

Reviewers: vitalybuka, eugenis

Reviewed By: eugenis

Subscribers: dberris, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D73816

Patch by Igor Sugak.
2020-02-03 16:28:47 -08:00
Kamil Rytarowski 4b8232d4f0 [compiler-rt] Adapt for ptrace(2) changes in NetBSD-9.99.30
Enable compat support for now legacy PT_LWPINFO.
Support PT_LWPSTATUS and PT_LWPNEXT.
2019-12-24 20:34:58 +01:00
Max Moroz a44ef027eb [compiler-rt] FuzzedDataProvider: do not call memcpy on empty vector.
Summary:
Some versions of memcpy mark pointer arguments as __nonnull, that triggers UBSan
errors even when the length passed is 0.

Reviewers: manojgupta, metzman

Subscribers: dberris, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D71031

[compiler-rt] FDP: assert that num_bytes_to_consume == 0 when size == 0.
2019-12-04 14:18:52 -08:00
Vedant Kumar f208b70fbc Revert "[Coverage] Revise format to reduce binary size"
This reverts commit e18531595b.

On Windows, there is an error:

http://lab.llvm.org:8011/builders/sanitizer-windows/builds/54963/steps/stage%201%20check/logs/stdio

error: C:\b\slave\sanitizer-windows\build\stage1\projects\compiler-rt\test\profile\Profile-x86_64\Output\instrprof-merging.cpp.tmp.v1.o: Failed to load coverage: Malformed coverage data
2019-12-04 10:35:14 -08:00
Vedant Kumar e18531595b [Coverage] Revise format to reduce binary size
Revise the coverage mapping format to reduce binary size by:

1. Naming function records and marking them `linkonce_odr`, and
2. Compressing filenames.

This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB)
and speeds up end-to-end single-threaded report generation by 10%. For
reference the compressed name data in llc is 81MB (__llvm_prf_names).

Rationale for changes to the format:

- With the current format, most coverage function records are discarded.
  E.g., more than 97% of the records in llc are *duplicate* placeholders
  for functions visible-but-not-used in TUs. Placeholders *are* used to
  show under-covered functions, but duplicate placeholders waste space.

- We reached general consensus about giving (1) a try at the 2017 code
  coverage BoF [1]. The thinking was that using `linkonce_odr` to merge
  duplicates is simpler than alternatives like teaching build systems
  about a coverage-aware database/module/etc on the side.

- Revising the format is expensive due to the backwards compatibility
  requirement, so we might as well compress filenames while we're at it.
  This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB).

See CoverageMappingFormat.rst for the details on what exactly has
changed.

Fixes PR34533 [2], hopefully.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html
[2] https://bugs.llvm.org/show_bug.cgi?id=34533

Differential Revision: https://reviews.llvm.org/D69471
2019-12-04 10:10:55 -08:00
Petr Hosek f35032e03d Reland "[CMake] Support installation of InstrProfData.inc"
This header fragment is useful on its own for any consumer that wants
to use custom instruction profile runtime with the LLVM instrumentation.
The concrete use case is in Fuchsia's kernel where we want to use
instruction profile instrumentation, but we cannot use the compiler-rt
runtime because it's not designed for use in the kernel environment.
This change allows installing this header as part of compiler-rt.

Differential Revision: https://reviews.llvm.org/D64532
2019-11-22 14:09:46 -08:00
Petr Hosek 262b10ba1f Revert "[CMake] Support installation of InstrProfData.inc"
This reverts commit f11bc1776f since it's
failing to build on some bots.
2019-11-22 12:00:23 -08:00
Petr Hosek f11bc1776f [CMake] Support installation of InstrProfData.inc
This header fragment is useful on its own for any consumer that wants
to use custom instruction profile runtime with the LLVM instrumentation.
The concrete use case is in Fuchsia's kernel where we want to use
instruction profile instrumentation, but we cannot use the compiler-rt
runtime because it's not designed for use in the kernel environment.
This change allows installing this header as part of compiler-rt.

Differential Revision: https://reviews.llvm.org/D64532
2019-11-22 11:52:50 -08:00
Kamil Rytarowski 01f91c3526 [compiler-rt] Sync NetBSD syscall hooks with 9.99.17
Document the minimal version supported as 9.0 and add compat code for
renamed syscalls after 9.0.
2019-11-03 16:22:02 +01:00
Evgenii Stepanov 13e04607f7 [asan] Provide an interface to update an allocation stack trace.
Summary:
Sometimes an allocation stack trace is not very informative. Provide a
way to replace it with a stack trace of the user's choice.

Reviewers: pcc, kcc

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D69208
2019-10-31 13:54:46 -07:00
Pierre Gousseau 1ae9e6918d [compiler-rt] Add ubsan interface header.
This is to document __ubsan_default_options().

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D67503

llvm-svn: 371822
2019-09-13 08:22:58 +00:00
Vitaly Buka d2af368aee [compiler-rt] Remove some cpplint filters
llvm-svn: 371704
2019-09-12 02:20:36 +00:00
Vitaly Buka 33f01663f7 [dfsan] Revert dfsan_set_label removal
It's part of interface, maybe it is used in external code.

llvm-svn: 371691
2019-09-11 23:43:23 +00:00
Vitaly Buka c0fa632236 Remove NOLINTs from compiler-rt
llvm-svn: 371687
2019-09-11 23:19:48 +00:00
Vitaly Buka 48eb4a27d1 Update compiler-rt cpplint.py
adb3500107

llvm-svn: 371675
2019-09-11 21:33:06 +00:00
Max Moroz f8744ab57a [compiler-rt] FuzzedDataProvider: use C++ headers only instead of a C/C++ mix.
Reviewers: Dor1s

Reviewed By: Dor1s

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

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D66017

llvm-svn: 368448
2019-08-09 16:00:53 +00:00
Max Moroz df3b465c9c [compiler-rt] Add ConsumeProbability and ConsumeFloatingPoint methods to FDP.
Summary:
Also slightly cleaned up the comments and changed the header's extension
back to `.h` as per comments on https://reviews.llvm.org/D65812.

New methods added:

* `ConsumeProbability` returns [0.0, 1.0] by consuming an unsigned integer value
   from the input data and dividing that value by the integer's max value.
* `ConsumeFloatingPointInRange` returns a floating point value in the given
   range. Relies on `ConsumeProbability` method. This method does not have the
   limitation of `std::uniform_real_distribution` that requires the given range
   to be <= the floating point type's max. If the range is too large, this
   implementation will additionally call `ConsumeBool` to decide whether the
   result will be in the first or the second half of the range.
* `ConsumeFloatingPoint` returns a floating point value in the range
  `[std::numeric_limits<T>::lowest(), std::numeric_limits<T>::min()]`.

Tested on Linux, Mac, Windows.


Reviewers: morehouse

Reviewed By: morehouse

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

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D65905

llvm-svn: 368331
2019-08-08 19:49:37 +00:00
Max Moroz 6c619aadc4 [compiler-rt] Rename FuzzedDataProvider.h to .hpp and other minor changes.
Summary:
.hpp makes more sense for this header as it's C++ only, plus it
contains the actual implementation.

Reviewers: Dor1s

Reviewed By: Dor1s

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

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D65812

llvm-svn: 368054
2019-08-06 16:02:39 +00:00
Max Moroz f1b0a93e3a [compiler-rt] Move FDP to include/fuzzer/FuzzedDataProvider.h for easier use.
Summary:
FuzzedDataProvider is a helper class for writing fuzz targets that fuzz
multple inputs simultaneously. The header is supposed to be used for fuzzing
engine agnostic fuzz targets (i.e. the same target can be used with libFuzzer,
AFL, honggfuzz, and other engines). The common thing though is that fuzz targets
are typically compiled with clang, as it provides all sanitizers as well as
different coverage instrumentation modes. Therefore, making this FDP class a
part of the compiler-rt installation package would make it easier to develop
and distribute fuzz targets across different projects, build systems, etc.
Some context also available in https://github.com/google/oss-fuzz/pull/2547.

This CL does not delete the header from `lib/fuzzer/utils` directory in order to
provide the downstream users some time for a smooth migration to the new
header location.

Reviewers: kcc, morehouse

Reviewed By: morehouse

Subscribers: lebedev.ri, kubamracek, dberris, mgorny, delcypher, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D65661

llvm-svn: 367917
2019-08-05 19:55:52 +00:00
Kostya Serebryany 6b936d88a4 [dfsan] Introduce dfsan_flush().
Summary:
dfsan_flush() allows to restart tain tracking from scratch in the same process.
The primary purpose right now is to allow more efficient data flow tracing
for DFT fuzzing: https://github.com/google/oss-fuzz/issues/1632

Reviewers: pcc

Reviewed By: pcc

Subscribers: delcypher, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D63037

llvm-svn: 363321
2019-06-13 20:11:06 +00:00
Pierre Gousseau 012ae4cc40 [compiler-rt] Update comments in asan header to doxygen format; NFC.
Add description to undocumented functions.
Improve spelling, grammar and formatting.

Patch by: Craig Flores, Filipe Cabecinhas, Pierre Gousseau

Reviewed By: Johannes Doerfert

Differential Revision: https://reviews.llvm.org/D62245

llvm-svn: 363038
2019-06-11 08:59:46 +00:00
Matt Morehouse a612b5adb7 [MSan] Introduce __msan_unpoison_param().
Summary:
This allows libFuzzer to unpoison parameter shadow before calling
LLVMFuzzerTestOneInput to eliminate the false positives described
in https://github.com/google/oss-fuzz/issues/2369.

Reviewers: eugenis

Reviewed By: eugenis

Subscribers: llvm-commits, metzman, kcc

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61751

llvm-svn: 360379
2019-05-09 21:50:57 +00:00
Evgeniy Stepanov d1a710047b [sanitizer] Implement reallocarray.
Summary:
It's a cross of calloc and realloc. Sanitizers implement calloc-like check for size
overflow.

Reviewers: vitalybuka, kcc

Subscribers: kubamracek, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D61108

llvm-svn: 359708
2019-05-01 17:33:01 +00:00
Nico Weber 885b790f89 Remove esan.
It hasn't seen active development in years, and it hasn't reached a
state where it was useful.

Remove the code until someone is interested in working on it again.

Differential Revision: https://reviews.llvm.org/D59133

llvm-svn: 355862
2019-03-11 20:23:40 +00:00
Evgeniy Stepanov f46a52b536 [hwasan, asan] Intercept vfork.
Summary:
Intercept vfork on arm, aarch64, i386 and x86_64.

Reviewers: pcc, vitalybuka

Subscribers: kubamracek, mgorny, javed.absar, krytarowski, kristof.beyls, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D58533

llvm-svn: 355030
2019-02-27 21:11:50 +00:00
Evgeniy Stepanov 45eea20d2a Revert "[asan] Fix vfork handling.", +1
Revert r354625, r354627 - multiple build failures.

llvm-svn: 354629
2019-02-21 22:02:24 +00:00
Evgeniy Stepanov df91386806 [hwasan,asan] Intercept vfork.
Summary: AArch64 only for now.

Reviewers: vitalybuka, pcc

Subscribers: srhines, kubamracek, mgorny, javed.absar, krytarowski, kristof.beyls, jdoerfert, #sanitizers, llvm-commits, kcc

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D58313

llvm-svn: 354625
2019-02-21 21:32:24 +00:00
Dmitry Vyukov 76e961207b tsan: add fiber support
This patch adds functions for managing fibers:

__tsan_get_current_fiber()
__tsan_create_fiber()
__tsan_destroy_fiber()
__tsan_switch_to_fiber()
__tsan_set_fiber_name()

See the added tests for use examples.

Author: yuri (Yuri Per)
Reviewed in: https://reviews.llvm.org/D54889

[The previous commit of this change was reverted,
this is a resubmit with a squashed fix for check_analyze.sh
and COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED]

llvm-svn: 353947
2019-02-13 13:21:24 +00:00
Diana Picus 4152a09e55 Revert "tsan: add fiber support"
This reverts commit r353817 because we think it broke AARch64 and
PowerPC buildbots.

llvm-svn: 353939
2019-02-13 11:32:56 +00:00
Dmitry Vyukov 6e7089ad40 tsan: add fiber support
This patch adds functions for managing fibers:

__tsan_get_current_fiber()
__tsan_create_fiber()
__tsan_destroy_fiber()
__tsan_switch_to_fiber()
__tsan_set_fiber_name()

See the added tests for use examples.

Author: yuri (Yuri Per)
Reviewed in: https://reviews.llvm.org/D54889

llvm-svn: 353817
2019-02-12 10:11:58 +00:00
Peter Collingbourne 886b7cc107 hwasan: Add __hwasan_init_static() function.
This function initializes enough of the runtime to be able to run
instrumented code in a statically linked executable. It replaces
__hwasan_shadow_init() which wasn't doing enough initialization for
instrumented code that uses either TLS or IFUNC to work.

Differential Revision: https://reviews.llvm.org/D57490

llvm-svn: 352816
2019-01-31 23:37:12 +00:00
James Y Knight 5d71fc5d7b Adjust documentation for git migration.
This fixes most references to the paths:
 llvm.org/svn/
 llvm.org/git/
 llvm.org/viewvc/
 github.com/llvm-mirror/
 github.com/llvm-project/
 reviews.llvm.org/diffusion/

to instead point to https://github.com/llvm/llvm-project.

This is *not* a trivial substitution, because additionally, all the
checkout instructions had to be migrated to instruct users on how to
use the monorepo layout, setting LLVM_ENABLE_PROJECTS instead of
checking out various projects into various subdirectories.

I've attempted to not change any scripts here, only documentation. The
scripts will have to be addressed separately.

Additionally, I've deleted one document which appeared to be outdated
and unneeded:
  lldb/docs/building-with-debug-llvm.txt

Differential Revision: https://reviews.llvm.org/D57330

llvm-svn: 352514
2019-01-29 16:37:27 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Peter Collingbourne 48807d0d35 xray: Add missing header to list of installed headers.
Spotted by gn's llvm/utils/gn/build/sync_source_lists_from_cmake.py script.

Differential Revision: https://reviews.llvm.org/D56797

llvm-svn: 351479
2019-01-17 21:11:49 +00:00
Nico Weber 07d8b321b3 Make compiler-rt CMakeLists.txt formatting a bit more like LLVM's usual formatting
llvm-svn: 351363
2019-01-16 18:12:45 +00:00
Kamil Rytarowski 4f343547ba Regenerate syscall hooks for NetBSD 8.99.25
Register new syscall getsockopt2.
Drop removed syscalls pmc_get_info and pmc_control.

While there address compiler warnings about potentially
unused variables.

llvm-svn: 345582
2018-10-30 11:10:36 +00:00
Vitaly Buka 83e57e2123 [sanitizer] Include inlined frames into __sanitizer_symbolize_pc output
Summary:
Behavior for existing used is not changing as the first line is going
to be the same, and it was invalid to try to read more lines.

New clients can read until they get empty string.

Reviewers: eugenis, morehouse

Subscribers: kubamracek, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D52743

llvm-svn: 343605
2018-10-02 17:01:18 +00:00
Jessica Paquette 9cfc8eca70 Revert "[sanitizer] Include inlined frames into __sanitizer_symbolize_pc output"
This reverts r343554.

It was breaking some bots:
http://lab.llvm.org:8080/green/job/clang-stage1-configure-RA/49997/

llvm-svn: 343600
2018-10-02 16:28:52 +00:00
Vitaly Buka ae1bbea890 [sanitizer] Include inlined frames into __sanitizer_symbolize_pc output
Summary:
Behavior for existing used is not changing as the first line is going
to be the same, and it was invalid to try to read more lines.

New clients can read until they get empty string.

Reviewers: eugenis, morehouse

Subscribers: kubamracek, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D52743

llvm-svn: 343554
2018-10-02 00:29:41 +00:00
Petr Hosek d197ebf3ed [XRay] Remove the deprecated __xray_log_init API
This API has been deprecated three months ago and shouldn't be used
anymore, all clients should migrate to the new string based API.

Differential Revision: https://reviews.llvm.org/D51606

llvm-svn: 342318
2018-09-15 02:55:42 +00:00
Kostya Serebryany 950a1a3936 [hwasan] introduce __hwasan_print_memory_usage
llvm-svn: 341592
2018-09-06 22:08:41 +00:00
Evgeniy Stepanov 4f0e10fff9 [hwasan] Add a (almost) no-interceptor mode.
Summary:
The idea behind this change is to allow sanitization of libc. We are prototyping on Bionic,
but the tool interface will be general enough (or at least generalizable) to support any other libc.

When libc depends on libclang_rt.hwasan, the latter can not interpose libc functions.
In fact, majority of interceptors become unnecessary when libc code is instrumented.

This change gets rid of most hwasan interceptors and provides interface for libc to notify
hwasan about thread creation and destruction events. Some interceptors (pthread_create)
are kept under #ifdef to enable testing with uninstrumented libc. They are expressed in
terms of the new libc interface.

The new cmake switch, COMPILER_RT_HWASAN_WITH_INTERCEPTORS, ON by default, builds testing
version of the library with the aforementioned pthread_create interceptor.
With the OFF setting, the library becomes more of a libc plugin.

Reviewers: vitalybuka, kcc, jfb

Subscribers: srhines, kubamracek, mgorny, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D50922

llvm-svn: 340216
2018-08-20 21:49:15 +00:00
Evgeniy Stepanov 37fb896572 Revert "Revert "[hwasan] Add __hwasan_handle_longjmp.""
This reapplies commit r339935 with the following changes:
* make longjmp test C, not C++, to avoid dependency on libc++/libstdc++
* untag pointer in memset interceptor

x86_64 does not have TBI, so hwasan barely works there. Tests must be carefully
written in a way that does not leak tagged pointer to system libraries.

llvm-svn: 339963
2018-08-16 23:17:14 +00:00
Evgeniy Stepanov 7f9b4af184 Revert "[hwasan] Add __hwasan_handle_longjmp."
This reverts commit 339935 which breaks hwasan tests on x86_64.

llvm-svn: 339957
2018-08-16 22:28:02 +00:00