1220 Commits

Author SHA1 Message Date
Peter Collingbourne
e08e68de21 Driver, IRGen: Set partitions on GlobalValues according to -fsymbol-partition flag.
Differential Revision: https://reviews.llvm.org/D62636

llvm-svn: 362829
2019-06-07 19:10:08 +00:00
Nemanja Ivanovic
6321c68065 Initial support for vectorization using MASSV (IBM MASS vector library)
Part 2 (the Clang portion) of D59881.

This patch (first of two patches) enables the vectorizer to recognize the
IBM MASS vector library routines. This patch specifically adds support for
recognizing the -vector-library=MASSV option, and defines mappings from IEEE
standard scalar math functions to generic PowerPC MASS vector counterparts.
For instance, the generic PowerPC MASS vector entry for double-precision
cbrt function is __cbrtd2_massv.

The second patch will further lower the generic PowerPC vector entries to
PowerPC subtarget-specific entries.
For instance, the PowerPC generic entry cbrtd2_massv is lowered to
cbrtd2_P9 for Power9 subtarget.

The overall support for MASS vector library is presented as such in two patches
for ease of review.

Patch by Jeeva Paudel.

Differential revision: https://reviews.llvm.org/D59881

llvm-svn: 362571
2019-06-05 01:57:57 +00:00
Alex Lorenz
6e2d36b60b Add clang source minimizer that reduces source to directives
that might affect the dependency list for a compilation

This commit introduces a dependency directives source minimizer to clang
that minimizes header and source files to the minimum necessary preprocessor
directives for evaluating includes. It reduces the source down to #define, #include,

The source minimizer works by lexing the input with a custom fast lexer that recognizes
the preprocessor directives it cares about, and emitting those directives in the minimized source.
It ignores source code, comments, and normalizes whitespace. It gives up and fails if seems
any directives that it doesn't recognize as valid (e.g. #define 0).

In addition to the source minimizer this patch adds a
-print-dependency-directives-minimized-source CC1 option that allows you to invoke the minimizer
from clang directly.

Differential Revision: https://reviews.llvm.org/D55463

llvm-svn: 362459
2019-06-03 22:59:17 +00:00
Sven van Haastregt
79a222fcf8 [OpenCL] Declare builtin functions using TableGen
This patch adds a `-fdeclare-opencl-builtins` command line option to
the clang frontend.  This enables clang to verify OpenCL C builtin
function declarations using a fast StringMatcher lookup, instead of
including the opencl-c.h file with the `-finclude-default-header`
option.  This avoids the large parse time penalty of the header file.

This commit only adds the basic infrastructure and some of the OpenCL
builtins.  It does not cover all builtins defined by the various OpenCL
specifications.  As such, it is not a replacement for
`-finclude-default-header` yet.

RFC: http://lists.llvm.org/pipermail/cfe-dev/2018-November/060041.html

Co-authored-by: Pierre Gondois
Co-authored-by: Joey Gouly
Co-authored-by: Sven van Haastregt

Differential Revision: https://reviews.llvm.org/D60763

llvm-svn: 362371
2019-06-03 09:39:11 +00:00
Kristof Umann
ac95c86511 [analyzer] List checker/plugin options in 3 categories: released, alpha, developer
Same patch as D62093, but for checker/plugin options, the only
difference being that options for alpha checkers are implicitly marked
as alpha.

Differential Revision: https://reviews.llvm.org/D62093

llvm-svn: 361566
2019-05-23 22:52:09 +00:00
Kristof Umann
7e55ed84d0 [analyzer] Hide developer-only checker/package options by default
These options are now only visible under
-analyzer-checker-option-help-developer.

Differential Revision: https://reviews.llvm.org/D61839

llvm-svn: 361561
2019-05-23 22:07:16 +00:00
Kristof Umann
5bc40d9b18 [analyzer] List checkers in 3 categories: released, alpha, developer
Previously, the only way to display the list of available checkers was
to invoke the analyzer with -analyzer-checker-help frontend flag. This
however wasn't really great from a maintainer standpoint: users came
across checkers meant strictly for development purposes that weren't to
be tinkered with, or those that were still in development. This patch
creates a clearer division in between these categories.

From now on, we'll have 3 flags to display the list checkers. These
lists are mutually exclusive and can be used in any combination (for
example to display both stable and alpha checkers).

-analyzer-checker-help: Displays the list for stable, production ready
                        checkers.

-analyzer-checker-help-alpha: Displays the list for in development
                              checkers. Enabling is discouraged
                              for non-development purposes.

-analyzer-checker-help-developer: Modeling and debug checkers. Modeling
                                  checkers shouldn't be enabled/disabled
                                  by hand, and debug checkers shouldn't
                                  be touched by users.

Differential Revision: https://reviews.llvm.org/D62093

llvm-svn: 361558
2019-05-23 21:46:51 +00:00
Kristof Umann
e8df27d925 [analyzer] Add a new frontend flag to display all checker options
Add the new frontend flag -analyzer-checker-option-help to display all
checker/package options.

Differential Revision: https://reviews.llvm.org/D57858

llvm-svn: 361552
2019-05-23 20:47:28 +00:00
Javed Absar
603a2bac05 [ARM][CMSE] Add commandline option and feature macro
Defines macro ARM_FEATURE_CMSE to 1 for v8-M targets and introduces
-mcmse option which for v8-M targets sets ARM_FEATURE_CMSE to 3.
A diagnostic is produced when the option is given on architectures
without support for Security Extensions.
Reviewed By: dmgreen, snidertm
Differential Revision: https://reviews.llvm.org/D59879

llvm-svn: 361261
2019-05-21 14:21:26 +00:00
Eric Christopher
030b17db66 Temporarily revert "Change -gz and -Wa,--compress-debug-sections to use gABI compression (SHF_COMPRESSED)"
This affects users of older (pre 2.26) binutils in such a way that they can't necessarily
work around it as it doesn't support the compress option on the command line. Reverting
to unblock them and we can revisit whether to make this change now or fix how we want
to express the option.

This reverts commit bdb21337e6e1732c9895966449c33c408336d295/r360403.

llvm-svn: 360703
2019-05-14 19:40:42 +00:00
Aaron Ballman
d06f391791 Add a new language mode for C2x; enable [[attribute]] support by default in C2x.
llvm-svn: 360667
2019-05-14 12:09:55 +00:00
Aaron Ballman
2ce598a44a Introduce the ability to dump the AST to JSON.
This adds the -ast-dump=json cc1 flag (in addition to -ast-dump=default, which is the default if no dump format is specified), as well as some initial AST dumping functionality and tests.

llvm-svn: 360622
2019-05-13 21:39:55 +00:00
Fangrui Song
bdb21337e6 Change -gz and -Wa,--compress-debug-sections to use gABI compression (SHF_COMPRESSED)
Since July 15, 2015 (binutils-gdb commit
19a7fe52ae3d0971e67a134bcb1648899e21ae1c, included in 2.26), gas
--compress-debug-sections=zlib (gcc -gz) means zlib-gabi:
SHF_COMPRESSED. Before that it meant zlib-gnu (.zdebug).

clang's -gz was introduced in rC306115 (Jun 2017) to indicate zlib-gnu. It
is 2019 now and it is not unreasonable to assume users of the new
feature to have new linkers (ld.bfd/gold >= 2.26, lld >= rLLD273661).

Change clang's default accordingly to improve standard conformance.
zlib-gnu becomes out of fashion and gets poorer toolchain support.
Its mangled names confuse tools and are more likely to cause problems.

Reviewed By: compnerd

Differential Revision: https://reviews.llvm.org/D61689

llvm-svn: 360403
2019-05-10 02:08:21 +00:00
Anastasia Stulova
eba9a6e08f [SPIR] Simplified target checking.
Switched to Triple::isSPIR() helper to simplify code.

Patch by kpet (Kevin Petit)!

Differential revision: https://reviews.llvm.org/D61639

llvm-svn: 360325
2019-05-09 10:25:45 +00:00
Kristof Umann
9f7fc9838a [analyzer] Don't display implementation checkers under -analyzer-checker-help, but do under the new flag -analyzer-checker-help-hidden
During my work on analyzer dependencies, I created a great amount of new
checkers that emitted no diagnostics at all, and were purely modeling some
function or another.

However, the user shouldn't really disable/enable these by hand, hence this
patch, which hides these by default. I intentionally chose not to hide alpha
checkers, because they have a scary enough name, in my opinion, to cause no
surprise when they emit false positives or cause crashes.

The patch introduces the Hidden bit into the TableGen files (you may remember
it before I removed it in D53995), and checkers that are either marked as
hidden, or are in a package that is marked hidden won't be displayed under
-analyzer-checker-help. -analyzer-checker-help-hidden, a new flag meant for
developers only, displays the full list.

Differential Revision: https://reviews.llvm.org/D60925

llvm-svn: 359720
2019-05-01 19:56:47 +00:00
Kristof Umann
b4788b26e2 [analyzer][NFC] Reimplement checker options
TL;DR:

* Add checker and package options to the TableGen files
* Added a new class called CmdLineOption, and both Package and Checker recieved
   a list<CmdLineOption> field.
* Added every existing checker and package option to Checkers.td.
* The CheckerRegistry class
  * Received some comments to most of it's inline classes
  * Received the CmdLineOption and PackageInfo inline classes, a list of
     CmdLineOption was added to CheckerInfo and PackageInfo
  * Added addCheckerOption and addPackageOption
  * Added a new field called Packages, used in addPackageOptions, filled up in
     addPackage

Detailed description:

In the last couple months, a lot of effort was put into tightening the
analyzer's command line interface. The main issue is that it's spectacularly
easy to mess up a lenghty enough invocation of the analyzer, and the user was
given no warnings or errors at all in that case.

We can divide the effort of resolving this into several chapters:

* Non-checker analyzer configurations:
    Gather every analyzer configuration into a dedicated file. Emit errors for
    non-existent configurations or incorrect values. Be able to list these
    configurations. Tighten AnalyzerOptions interface to disallow making such
    a mistake in the future.

* Fix the "Checker Naming Bug" by reimplementing checker dependencies:
    When cplusplus.InnerPointer was enabled, it implicitly registered
    unix.Malloc, which implicitly registered some sort of a modeling checker
    from the CStringChecker family. This resulted in all of these checker
    objects recieving the name "cplusplus.InnerPointer", making AnalyzerOptions
    asking for the wrong checker options from the command line:
      cplusplus.InnerPointer:Optimisic
    istead of
      unix.Malloc:Optimistic.
    This was resolved by making CheckerRegistry responsible for checker
    dependency handling, instead of checkers themselves.

* Checker options: (this patch included!)
    Same as the first item, but for checkers.

(+ minor fixes here and there, and everything else that is yet to come)

There were several issues regarding checker options, that non-checker
configurations didn't suffer from: checker plugins are loaded runtime, and they
could add new checkers and new options, meaning that unlike for non-checker
configurations, we can't collect every checker option purely by generating code.
Also, as seen from the "Checker Naming Bug" issue raised above, they are very
rarely used in practice, and all sorts of skeletons fell out of the closet while
working on this project.

They were extremely problematic for users as well, purely because of how long
they were. Consider the following monster of a checker option:

  alpha.cplusplus.UninitializedObject:CheckPointeeInitialization=false

While we were able to verify whether the checker itself (the part before the
colon) existed, any errors past that point were unreported, easily resulting
in 7+ hours of analyses going to waste.

This patch, similarly to how dependencies were reimplemented, uses TableGen to
register checker options into Checkers.td, so that Checkers.inc now contains
entries for both checker and package options. Using the preprocessor,
Checkers.inc is converted into code in CheckerRegistry, adding every builtin
(checkers and packages that have an entry in the Checkers.td file) checker and
package option to the registry. The new addPackageOption and addCheckerOption
functions expose the same functionality to statically-linked non-builtin and
plugin checkers and packages as well.

Emitting errors for incorrect user input, being able to list these options, and
some other functionalies will land in later patches.

Differential Revision: https://reviews.llvm.org/D57855

llvm-svn: 358752
2019-04-19 12:32:10 +00:00
Richard Smith
8af8b8611c [C++20] Implement context-sensitive header-name lexing and pp-import parsing in the preprocessor.
llvm-svn: 358231
2019-04-11 21:18:23 +00:00
Fangrui Song
75e74e077c Range-style std::find{,_if} -> llvm::find{,_if}. NFC
llvm-svn: 357359
2019-03-31 08:48:19 +00:00
Anton Afanasyev
d880de2d19 Adds -ftime-trace option to clang that produces Chrome chrome://tracing compatible JSON profiling output dumps.
This change adds hierarchical "time trace" profiling blocks that can be visualized in Chrome, in a "flame chart" style. Each profiling block can have a "detail" string that for example indicates the file being processed, template name being instantiated, function being optimized etc.

This is taken from GitHub PR: https://github.com/aras-p/llvm-project-20170507/pull/2

Patch by Aras Pranckevičius.

Differential Revision: https://reviews.llvm.org/D58675

llvm-svn: 357340
2019-03-30 08:42:48 +00:00
Francis Visoiu Mistrih
dd42236c6c Reland "[Remarks] Add -foptimization-record-passes to filter remark emission"
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.

This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`

will only emit the remarks coming from the pass `inline`.

This adds:

* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin

Differential Revision: https://reviews.llvm.org/D59268

Original llvm-svn: 355964

llvm-svn: 355984
2019-03-12 21:22:27 +00:00
Francis Visoiu Mistrih
1d6c47ad2b Revert "[Remarks] Add -foptimization-record-passes to filter remark emission"
This reverts commit 20fff32b7d1f1a1bd417b22aa9f26ededd97a3e5.

llvm-svn: 355976
2019-03-12 20:54:18 +00:00
Francis Visoiu Mistrih
20fff32b7d [Remarks] Add -foptimization-record-passes to filter remark emission
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.

This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`

will only emit the remarks coming from the pass `inline`.

This adds:

* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin

Differential Revision: https://reviews.llvm.org/D59268

llvm-svn: 355964
2019-03-12 20:28:50 +00:00
Rong Xu
a4a09b2398 [PGO] Clang part of change for context-sensitive PGO (part1)
Part 1 of CSPGO change in Clang. This includes changes in clang options
and calls to llvm PassManager. Tests will be committed in part2.
This change needs the PassManager change in llvm.

Differential Revision: https://reviews.llvm.org/D54176

llvm-svn: 355331
2019-03-04 20:21:31 +00:00
Pierre Gousseau
ae5303d010 [Driver] Allow enum SanitizerOrdinal to represent more than 64 different sanitizer checks, NFC.
enum SanitizerOrdinal has reached maximum capacity, this change extends the capacity to 128 sanitizer checks.
This can eventually allow us to add gcc 8's options "-fsanitize=pointer-substract" and "-fsanitize=pointer-compare".

This is a recommit of r354873 but with a fix for unqualified lookup error in lldb cmake build bot.

Fixes: https://llvm.org/PR39425

Differential Revision: https://reviews.llvm.org/D57914

llvm-svn: 355190
2019-03-01 10:05:15 +00:00
Pierre Gousseau
40ad3d2aa4 revert r354873 as this breaks lldb builds.
llvm-svn: 354875
2019-02-26 13:50:29 +00:00
Pierre Gousseau
44fad947a5 [Driver] Allow enum SanitizerOrdinal to represent more than 64 different sanitizer checks, NFC.
enum SanitizerOrdinal has reached maximum capacity, this change extends the capacity to 128 sanitizer checks.
This can eventually allow us to add gcc 8's options "-fsanitize=pointer-substract" and "-fsanitize=pointer-compare".

Fixes: https://llvm.org/PR39425

Differential Revision: https://reviews.llvm.org/D57914

llvm-svn: 354873
2019-02-26 13:30:14 +00:00
Alexey Bader
3f62fa69a7 [SYCL] Add clang front-end option to enable SYCL device compilation flow.
Patch by Mariya Podchishchaeva <mariya.podchishchaeva@intel.com>

llvm-svn: 354773
2019-02-25 11:48:48 +00:00
Richard Smith
10ab78e854 Enable coroutines under -std=c++2a.
llvm-svn: 354736
2019-02-23 21:06:26 +00:00
Alexey Bataev
8061acd501 [OPENMP][NVPTX]Use faster teams reduction algorithm.
A faster way to reduce the values in teams reductions was found, the
codegen is updated to use this faster algorithm and new runtime functions.

llvm-svn: 354479
2019-02-20 16:36:22 +00:00
Oliver Stannard
e3c8ce8b75 [ARM] Add pre-defined macros for ROPI and RWPI
This adds ACLE-defined macros to test for code being compiled in the ROPI and
RWPI position-independence modes.

Differential revision: https://reviews.llvm.org/D23610

llvm-svn: 354265
2019-02-18 12:39:47 +00:00
Alexey Bataev
c416e64731 [OPENMP]Delay emission of the error messages for the exceptions.
Fixed diagnostic emission for the exceptions support in case of the
compilation of OpenMP code for the devices. From now on, it uses delayed
diagnostics mechanism, previously used for CUDA only. It allow to
diagnose not allowed used of exceptions only in functions that are going
to be codegen'ed.

llvm-svn: 353542
2019-02-08 18:02:25 +00:00
Alexey Bataev
346fb4bbcd Revert "[OPENMP]Initial support for the delayed diagnostics."
This reverts commit r353540. Erroneously committed, need to fix the
message and description.

llvm-svn: 353541
2019-02-08 17:42:00 +00:00
Alexey Bataev
5e62adad0d [OPENMP]Initial support for the delayed diagnostics.
It is important to delay the emission of the diagnostic messages for the
functions unless it is proved that the function is going to be used on
the device side. It is required to support compilation with some of the
target-specific system headers.

llvm-svn: 353540
2019-02-08 17:38:09 +00:00
Philip Pfaffe
e3f105c651 [NewPM] Add support for new-PM plugins to clang
Summary:
This adds support for new-PM plugin loading to clang. The option
`-fpass-plugin=` may be used to specify a dynamic shared object file
that adheres to the PassPlugin API.

Tested: created simple plugin that registers an EP callback; with optimization level > 0, the pass is run as expected.

Committed on behalf of Marco Elver

Differential Revision: https://reviews.llvm.org/D56935

llvm-svn: 352972
2019-02-02 23:19:32 +00:00
Nico Weber
0abcafd8a4 Make clang/test/Index/pch-from-libclang.c pass in more places
- fixes the test on macOS with LLVM_ENABLE_PIC=OFF
- together with D57343, gets the test to pass on Windows
- makes it run everywhere (it seems to just pass on Linux)

The main change is to pull out the resource directory computation into a
function shared by all 3 places that do it. In CIndexer.cpp, this now works no
matter if libclang is in lib/ or bin/ or statically linked to a binary in bin/.


Differential Revision: https://reviews.llvm.org/D57345

llvm-svn: 352803
2019-01-31 22:15:32 +00:00
Scott Linder
bef2663751 Add -fapply-global-visibility-to-externs for -cc1
Introduce an option to request global visibility settings be applied to
declarations without a definition or an explicit visibility, rather than
the existing behavior of giving these default visibility. When the
visibility of all or most extern definitions are known this allows for
the same optimisations -fvisibility permits without updating source code
to annotate all declarations.

Differential Revision: https://reviews.llvm.org/D56868

llvm-svn: 352391
2019-01-28 17:12:19 +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
Teresa Johnson
84cecfcb3d [LTO] Add option to enable LTOUnit splitting, and disable unless needed
Summary:
Adds a new -f[no]split-lto-unit flag that is disabled by default to
control module splitting during ThinLTO. It is automatically enabled
for -fsanitize=cfi and -fwhole-program-vtables.

The new EnableSplitLTOUnit codegen flag is passed down to llvm
via a new module flag of the same name.

Depends on D53890.

Reviewers: pcc

Subscribers: ormris, mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, cfe-commits, llvm-commits

Differential Revision: https://reviews.llvm.org/D53891

llvm-svn: 350949
2019-01-11 18:32:07 +00:00
Gheorghe-Teodor Bercea
a3afcf2445 [OpenMP] Add flag for preventing the extension to 64 bits for the collapse loop counter
Summary: Introduce a compiler flag for cases when the user knows that the collapsed loop counter can be safely represented using at most 32 bits. This will prevent the emission of expensive mathematical operations (such as the div operation) on the iteration variable using 64 bits where 32 bit operations are sufficient.

Reviewers: ABataev, caomhin

Reviewed By: ABataev

Subscribers: hfinkel, kkwli0, guansong, cfe-commits

Differential Revision: https://reviews.llvm.org/D55928

llvm-svn: 350758
2019-01-09 20:38:35 +00:00
Nico Weber
9f0c21c1e0 Move -add-plugin validation after -load was executed.
Moves the code added in r350340 around a bit, to hopefully make the existing
plugin tests pass when clang is built with examples enabled.

llvm-svn: 350451
2019-01-05 01:10:20 +00:00
Peter Collingbourne
87f477b5e4 hwasan: Implement lazy thread initialization for the interceptor ABI.
The problem is similar to D55986 but for threads: a process with the
interceptor hwasan library loaded might have some threads started by
instrumented libraries and some by uninstrumented libraries, and we
need to be able to run instrumented code on the latter.

The solution is to perform per-thread initialization lazily. If a
function needs to access shadow memory or add itself to the per-thread
ring buffer its prologue checks to see whether the value in the
sanitizer TLS slot is null, and if so it calls __hwasan_thread_enter
and reloads from the TLS slot. The runtime does the same thing if it
needs to access this data structure.

This change means that the code generator needs to know whether we
are targeting the interceptor runtime, since we don't want to pay
the cost of lazy initialization when targeting a platform with native
hwasan support. A flag -fsanitize-hwaddress-abi={interceptor,platform}
has been introduced for selecting the runtime ABI to target. The
default ABI is set to interceptor since it's assumed that it will
be more common that users will be compiling application code than
platform code.

Because we can no longer assume that the TLS slot is initialized,
the pthread_create interceptor is no longer necessary, so it has
been removed.

Ideally, lazy initialization should only cost one instruction in the
hot path, but at present the call may cause us to spill arguments
to the stack, which means more instructions in the hot path (or
theoretically in the cold path if the spills are moved with shrink
wrapping). With an appropriately chosen calling convention for
the per-thread initialization function (TODO) the hot path should
always need just one instruction and the cold path should need two
instructions with no spilling required.

Differential Revision: https://reviews.llvm.org/D56038

llvm-svn: 350429
2019-01-04 19:27:04 +00:00
Nico Weber
ca27a2b037 Validate -add-plugin arguments.
-plugin already prints an error if the name of an unknown plugin is passed.
-add-plugin used to silently ignore that, now it errors too.

Differential Revision: https://reviews.llvm.org/D56273

llvm-svn: 350340
2019-01-03 18:26:06 +00:00
JF Bastien
14daa20be1 Automatic variable initialization
Summary:
Add an option to initialize automatic variables with either a pattern or with
zeroes. The default is still that automatic variables are uninitialized. Also
add attributes to request uninitialized on a per-variable basis, mainly to disable
initialization of large stack arrays when deemed too expensive.

This isn't meant to change the semantics of C and C++. Rather, it's meant to be
a last-resort when programmers inadvertently have some undefined behavior in
their code. This patch aims to make undefined behavior hurt less, which
security-minded people will be very happy about. Notably, this means that
there's no inadvertent information leak when:

  - The compiler re-uses stack slots, and a value is used uninitialized.
  - The compiler re-uses a register, and a value is used uninitialized.
  - Stack structs / arrays / unions with padding are copied.

This patch only addresses stack and register information leaks. There's many
more infoleaks that we could address, and much more undefined behavior that
could be tamed. Let's keep this patch focused, and I'm happy to address related
issues elsewhere.

To keep the patch simple, only some `undef` is removed for now, see
`replaceUndef`. The padding-related infoleaks are therefore not all gone yet.
This will be addressed in a follow-up, mainly because addressing padding-related
leaks should be a stand-alone option which is implied by variable
initialization.

There are three options when it comes to automatic variable initialization:

  0. Uninitialized

    This is C and C++'s default. It's not changing. Depending on code
    generation, a programmer who runs into undefined behavior by using an
    uninialized automatic variable may observe any previous value (including
    program secrets), or any value which the compiler saw fit to materialize on
    the stack or in a register (this could be to synthesize an immediate, to
    refer to code or data locations, to generate cookies, etc).

  1. Pattern initialization

    This is the recommended initialization approach. Pattern initialization's
    goal is to initialize automatic variables with values which will likely
    transform logic bugs into crashes down the line, are easily recognizable in
    a crash dump, without being values which programmers can rely on for useful
    program semantics. At the same time, pattern initialization tries to
    generate code which will optimize well. You'll find the following details in
    `patternFor`:

    - Integers are initialized with repeated 0xAA bytes (infinite scream).
    - Vectors of integers are also initialized with infinite scream.
    - Pointers are initialized with infinite scream on 64-bit platforms because
      it's an unmappable pointer value on architectures I'm aware of. Pointers
      are initialize to 0x000000AA (small scream) on 32-bit platforms because
      32-bit platforms don't consistently offer unmappable pages. When they do
      it's usually the zero page. As people try this out, I expect that we'll
      want to allow different platforms to customize this, let's do so later.
    - Vectors of pointers are initialized the same way pointers are.
    - Floating point values and vectors are initialized with a negative quiet
      NaN with repeated 0xFF payload (e.g. 0xffffffff and 0xffffffffffffffff).
      NaNs are nice (here, anways) because they propagate on arithmetic, making
      it more likely that entire computations become NaN when a single
      uninitialized value sneaks in.
    - Arrays are initialized to their homogeneous elements' initialization
      value, repeated. Stack-based Variable-Length Arrays (VLAs) are
      runtime-initialized to the allocated size (no effort is made for negative
      size, but zero-sized VLAs are untouched even if technically undefined).
    - Structs are initialized to their heterogeneous element's initialization
      values. Zero-size structs are initialized as 0xAA since they're allocated
      a single byte.
    - Unions are initialized using the initialization for the largest member of
      the union.

    Expect the values used for pattern initialization to change over time, as we
    refine heuristics (both for performance and security). The goal is truly to
    avoid injecting semantics into undefined behavior, and we should be
    comfortable changing these values when there's a worthwhile point in doing
    so.

    Why so much infinite scream? Repeated byte patterns tend to be easy to
    synthesize on most architectures, and otherwise memset is usually very
    efficient. For values which aren't entirely repeated byte patterns, LLVM
    will often generate code which does memset + a few stores.

  2. Zero initialization

    Zero initialize all values. This has the unfortunate side-effect of
    providing semantics to otherwise undefined behavior, programs therefore
    might start to rely on this behavior, and that's sad. However, some
    programmers believe that pattern initialization is too expensive for them,
    and data might show that they're right. The only way to make these
    programmers wrong is to offer zero-initialization as an option, figure out
    where they are right, and optimize the compiler into submission. Until the
    compiler provides acceptable performance for all security-minded code, zero
    initialization is a useful (if blunt) tool.

I've been asked for a fourth initialization option: user-provided byte value.
This might be useful, and can easily be added later.

Why is an out-of band initialization mecanism desired? We could instead use
-Wuninitialized! Indeed we could, but then we're forcing the programmer to
provide semantics for something which doesn't actually have any (it's
uninitialized!). It's then unclear whether `int derp = 0;` lends meaning to `0`,
or whether it's just there to shut that warning up. It's also way easier to use
a compiler flag than it is to manually and intelligently initialize all values
in a program.

Why not just rely on static analysis? Because it cannot reason about all dynamic
code paths effectively, and it has false positives. It's a great tool, could get
even better, but it's simply incapable of catching all uses of uninitialized
values.

Why not just rely on memory sanitizer? Because it's not universally available,
has a 3x performance cost, and shouldn't be deployed in production. Again, it's
a great tool, it'll find the dynamic uses of uninitialized variables that your
test coverage hits, but it won't find the ones that you encounter in production.

What's the performance like? Not too bad! Previous publications [0] have cited
2.7 to 4.5% averages. We've commmitted a few patches over the last few months to
address specific regressions, both in code size and performance. In all cases,
the optimizations are generally useful, but variable initialization benefits
from them a lot more than regular code does. We've got a handful of other
optimizations in mind, but the code is in good enough shape and has found enough
latent issues that it's a good time to get the change reviewed, checked in, and
have others kick the tires. We'll continue reducing overheads as we try this out
on diverse codebases.

Is it a good idea? Security-minded folks think so, and apparently so does the
Microsoft Visual Studio team [1] who say "Between 2017 and mid 2018, this
feature would have killed 49 MSRC cases that involved uninitialized struct data
leaking across a trust boundary. It would have also mitigated a number of bugs
involving uninitialized struct data being used directly.". They seem to use pure
zero initialization, and claim to have taken the overheads down to within noise.
Don't just trust Microsoft though, here's another relevant person asking for
this [2]. It's been proposed for GCC [3] and LLVM [4] before.

What are the caveats? A few!

  - Variables declared in unreachable code, and used later, aren't initialized.
    This goto, Duff's device, other objectionable uses of switch. This should
    instead be a hard-error in any serious codebase.
  - Volatile stack variables are still weird. That's pre-existing, it's really
    the language's fault and this patch keeps it weird. We should deprecate
    volatile [5].
  - As noted above, padding isn't fully handled yet.

I don't think these caveats make the patch untenable because they can be
addressed separately.

Should this be on by default? Maybe, in some circumstances. It's a conversation
we can have when we've tried it out sufficiently, and we're confident that we've
eliminated enough of the overheads that most codebases would want to opt-in.
Let's keep our precious undefined behavior until that point in time.

How do I use it:

  1. On the command-line:

    -ftrivial-auto-var-init=uninitialized (the default)
    -ftrivial-auto-var-init=pattern
    -ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang

  2. Using an attribute:

    int dont_initialize_me __attribute((uninitialized));

  [0]: https://users.elis.ugent.be/~jsartor/researchDocs/OOPSLA2011Zero-submit.pdf
  [1]: https://twitter.com/JosephBialek/status/1062774315098112001
  [2]: https://outflux.net/slides/2018/lss/danger.pdf
  [3]: https://gcc.gnu.org/ml/gcc-patches/2014-06/msg00615.html
  [4]: 776a0955ef
  [5]: http://wg21.link/p1152

I've also posted an RFC to cfe-dev: http://lists.llvm.org/pipermail/cfe-dev/2018-November/060172.html

<rdar://problem/39131435>

Reviewers: pcc, kcc, rsmith

Subscribers: JDevlieghere, jkorous, dexonsmith, cfe-commits

Differential Revision: https://reviews.llvm.org/D54604

llvm-svn: 349442
2018-12-18 05:12:21 +00:00
Alex Lorenz
0a264f3928 [darwin] parse the SDK settings from SDKSettings.json if it exists and
pass in the -target-sdk-version to the compiler and backend

This commit adds support for reading the SDKSettings.json file in the Darwin
driver. This file is used by the driver to determine the SDK's version, and it
uses that information to pass it down to the compiler using the new
-target-sdk-version= option. This option is then used to set the appropriate
SDK Version module metadata introduced in r349119.

Note: I had to adjust the two ast tests as the SDKROOT environment variable
on macOS caused SDK version to be picked up for the compilation of source file
but not the AST.

rdar://45774000

Differential Revision: https://reviews.llvm.org/D55673

llvm-svn: 349380
2018-12-17 19:19:15 +00:00
Scott Linder
de6beb02a5 Implement -frecord-command-line (-frecord-gcc-switches)
Implement options in clang to enable recording the driver command-line
in an ELF section.

Implement a new special named metadata, llvm.commandline, to support
frontends embedding their command-line options in IR/ASM/ELF.

This differs from the GCC implementation in some key ways:

* In GCC there is only one command-line possible per compilation-unit,
  in LLVM it mirrors llvm.ident and multiple are allowed.
* In GCC individual options are separated by NULL bytes, in LLVM entire
  command-lines are separated by NULL bytes. The advantage of the GCC
  approach is to clearly delineate options in the face of embedded
  spaces. The advantage of the LLVM approach is to support merging
  multiple command-lines unambiguously, while handling embedded spaces
  with escaping.

Differential Revision: https://reviews.llvm.org/D54487
Clang Differential Revision: https://reviews.llvm.org/D54489

llvm-svn: 349155
2018-12-14 15:38:15 +00:00
Richard Trieu
6368818fd5 Move CodeGenOptions from Frontend to Basic
Basic uses CodeGenOptions and should not depend on Frontend.

llvm-svn: 348827
2018-12-11 03:18:39 +00:00
Raphael Isemann
b23ccecbb0 Misc typos fixes in ./lib folder
Summary: Found via `codespell -q 3 -I ../clang-whitelist.txt -L uint,importd,crasher,gonna,cant,ue,ons,orign,ned`

Reviewers: teemperor

Reviewed By: teemperor

Subscribers: teemperor, jholewinski, jvesely, nhaehnle, whisperity, jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D55475

llvm-svn: 348755
2018-12-10 12:37:46 +00:00
Pete Cooper
e388680dfa Convert some ObjC msgSends to runtime calls.
It is faster to directly call the ObjC runtime for methods such as alloc/allocWithZone instead of sending a message to those functions.

This patch adds support for converting messages to alloc/allocWithZone to their equivalent runtime calls.

Tests included for the positive case of applying this transformation, negative tests that we ensure we only convert "alloc" to objc_alloc, not "alloc2", and also a driver test to ensure we enable this only for supported runtime versions.

Reviewed By: rjmccall

https://reviews.llvm.org/D55349

llvm-svn: 348687
2018-12-08 05:13:50 +00:00
Alex Lorenz
2e7ab55e65 [frontend][darwin] warn_stdlibcxx_not_found: supress warning for preprocessed input
Addresses second post-commit feedback for r335081 from Nico

llvm-svn: 348540
2018-12-06 22:45:58 +00:00
Vitaly Buka
8076c57fd2 [asan] Add clang flag -fsanitize-address-use-odr-indicator
Reviewers: eugenis, m.ostapenko, ygribov

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D55157

llvm-svn: 348327
2018-12-05 01:44:31 +00:00