Commit Graph

294948 Commits

Author SHA1 Message Date
David Carlier 59a339ab45 [Docs] Update supported oses for safestack, ubsan, asan, tsan and msan
Adding oses others than Linux.

llvm-svn: 337926
2018-07-25 13:55:06 +00:00
Louis Dionne f636411a5e [NFC] Fix grammatical mistakes in libc++ FileTimeType design docs
llvm-svn: 337925
2018-07-25 13:40:49 +00:00
Pavel Labath b4e17c29dd Revert "dwarfgen: Add support for generating the debug_str_offsets section"
This reverts commit r337910 as it's generating "ambiguous call to
addAttribute" errors on some bots.

Will resubmit once I get a chance to look into the problem.

llvm-svn: 337924
2018-07-25 12:52:30 +00:00
Mikhail R. Gadelha f142c965e4 [analyzer] Use the macro REGISTER_TRAIT_WITH_PROGRAMSTATE in the Z3 backend
Summary:
The macro was manually expanded in the Z3 backend and this patch adds it back.

Adding the expanded code is dangerous as the macro may change in the future and the expanded code might be left outdated.

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49769

llvm-svn: 337923
2018-07-25 12:49:47 +00:00
Mikhail R. Gadelha 5c3d032e70 [analyzer] Removed API used by the Refutation Manager from SMTConstraintManager and replace by proper calls to SMTSolver
Summary:
Third patch in the refactoring series, to decouple the SMT Solver from the Refutation Manager (1st: D49668, 2nd: D49767).

The refutation API in the `SMTConstraintManager` was a hack to allow us to create an SMT solver and verify the constraints; it was conceptually wrong from the start. Now, we don't actually need to use the `SMTConstraintManager` and can create an SMT object directly, add the constraints and check them.

While updating the Falsification visitor, I inlined the two functions that were used to collect the constraints and add them to the solver.

As a result of this patch, we could move the SMT API elsewhere and as it's not really dependent on the CSA anymore. Maybe we can create a new dir (utils/smt) for Z3 and future solvers?

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49768

llvm-svn: 337922
2018-07-25 12:49:43 +00:00
Mikhail R. Gadelha 8628e2cd54 [analyzer] Moved code from SMTConstraintManager to SMTSolver
Summary:
This is the second part of D49668, and moves all the code that's not specific to a ConstraintManager to SMTSolver.

No functional change intended.

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49767

llvm-svn: 337921
2018-07-25 12:49:37 +00:00
Mikhail R. Gadelha c7f89ad69d [analyzer] Try to minimize the number of equivalent bug reports evaluated by the refutation manager
Summary:
This patch changes how the SMT bug refutation runs in an equivalent bug report class.

Now, all other visitor are executed until they find a valid bug or mark all bugs as invalid. When the one valid bug is found (and crosscheck is enabled), the SMT refutation checks the satisfiability of this single bug.

If the bug is still valid after checking with Z3, it is returned and a bug report is created. If the bug is found to be invalid, the next bug report in the equivalent class goes through the same process, until we find a valid bug or all bugs are marked as invalid.

Massive speedups when verifying redis/src/rax.c, from 1500s to 10s.

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49693

llvm-svn: 337920
2018-07-25 12:49:32 +00:00
Mikhail R. Gadelha 456ecffe11 [analyzer] Moved non solver specific code from Z3ConstraintManager to SMTConstraintManager
Summary:
This patch moves a lot of code from `Z3ConstraintManager` to `SMTConstraintManager`, leaving only the necessary:
* `canReasonAbout` which returns if a Solver can handle a given `SVal` (should be moved to `SMTSolver` in the future).
* `removeDeadBindings`, `assumeExpr` and `print`: methods that need to use `ConstraintZ3Ty`, can probably be moved to `SMTConstraintManager` in the future.

The patch creates a new file, `SMTConstraintManager.cpp` with the moved code. Conceptually, this is move in the right direction and needs further improvements: `SMTConstraintManager` still does a lot of things that are not required by a `ConstraintManager`.

We ought to move the unrelated to `SMTSolver` and remove everything that's not related to a `ConstraintManager`. In particular, we could remove `addRangeConstraints` and `isModelFeasible`, and make the refutation manager create an Z3Solver directly.

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: mgorny, xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49668

llvm-svn: 337919
2018-07-25 12:49:29 +00:00
Mikhail R. Gadelha 635378b783 [analyzer] Implemented SMT generic API
Summary:
Created new SMT generic API.

Small changes to `Z3ConstraintManager` because of the new generic objects (`SMTSort` and `SMTExpr`) returned by `SMTSolver`.

Reviewers: george.karpenkov, NoQ

Reviewed By: george.karpenkov

Subscribers: mgorny, xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49495

llvm-svn: 337918
2018-07-25 12:49:23 +00:00
Mikhail R. Gadelha ca6983b95a [analyzer] Create generic SMT Expr class
Summary:
New base class for all future SMT Exprs.

No major changes except moving `areEquivalent` and `getFloatSemantics` outside of `Z3Expr` to keep the class minimal.

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49551

llvm-svn: 337917
2018-07-25 12:49:19 +00:00
Mikhail R. Gadelha cb9e68dc97 [analyzer] Create generic SMT Sort Class
Summary:
New base class for all future SMT sorts.

The only change is that the class implements methods `isBooleanSort()`, `isBitvectorSort()` and `isFloatSort()` so it doesn't rely on `Z3`'s enum.

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49550

llvm-svn: 337916
2018-07-25 12:49:15 +00:00
Mikhail R. Gadelha 19f0761020 [analyzer] Moved static Context to class member
Summary:
Although it is a big patch, the changes are simple:
1. There is one `Z3_Context` now, member of the `SMTConstraintManager` class.
2. `Z3Expr`, `Z3Sort`, `Z3Model` and `Z3Solver` are constructed with a reference to the `Z3_Context` in `SMTConstraintManager`.
3. All static functions are now members of `Z3Solver`, e.g, the `SMTConstraintManager` now calls `Solver.fromBoolean(false)` instead of `Z3Expr::fromBoolean(false)`.

Most of the patch only move stuff around except:
1. New method `Z3Sort MkSort(const QualType &Ty, unsigned BitWidth)`, that creates a sort based on the `QualType` and its width. Used to simplify the `fromData` method.

Unfortunate consequence of this patch:
1. `getInterpretation` was moved from `Z3Model` class to `Z3Solver`, because it needs to create a `Z3Sort` before returning the interpretation. This can be fixed by changing both `toAPFloat` and `toAPSInt` by removing the dependency of `Z3Sort` (it's only used to check which Sort was created and to retrieve the type width).

Reviewers: NoQ, george.karpenkov, ddcc

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49236

llvm-svn: 337915
2018-07-25 12:49:11 +00:00
Mikhail R. Gadelha 0b2aa685a6 [analyzer] Create generic SMT Context class
Summary:
This patch creates `SMTContext` which will wrap a specific SMT context, through `SMTSolverContext`.

The templated `SMTSolverContext` class it's a simple wrapper around a SMT specific context (currently only used in the Z3 backend), while `Z3Context` inherits `SMTSolverContext<Z3_context>` and implements solver specific operations like initialization and destruction of the context.

This separation was done because:

1. We might want to keep one single context, shared across different `SMTConstraintManager`s. It can be achieved by constructing a `SMTContext`, through a function like `CreateSMTContext(Z3)`, `CreateSMTContext(BOOLECTOR)`, etc. The rest of the CSA only need to know about `SMTContext`, so maybe it's a good idea moving `SMTSolverContext` to a separate header in the future.

2. Any generic SMT operation will only require one `SMTSolverContext`object, which can access the specific context by calling `getContext()`.

Reviewers: NoQ, george.karpenkov

Reviewed By: george.karpenkov

Subscribers: xazax.hun, szepet, a.sidorin

Differential Revision: https://reviews.llvm.org/D49233

llvm-svn: 337914
2018-07-25 12:49:07 +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
Petar Jovanovic 58c0210023 [MIPS GlobalISel] Lower pointer arguments
Add support for lowering pointer arguments.
Changing type from pointer to integer is already done in
MipsTargetLowering::getRegisterTypeForCallingConv.

Patch by Petar Avramovic.

Differential Revision: https://reviews.llvm.org/D49419

llvm-svn: 337912
2018-07-25 12:35:01 +00:00
Jonas Hahnfeld ba5ec9c684 [OMPT] Fix typo in test parallel/nested_thread_num.c
This caused test failures with GCC since its initial commit in
r336085 (https://reviews.llvm.org/D46533).

llvm-svn: 337911
2018-07-25 12:34:31 +00:00
Pavel Labath 7a59e3bf37 dwarfgen: Add support for generating the debug_str_offsets section
Summary:
The motivation for this is D49493, where we'd like to test details of
debug_str_offsets behavior which is difficult to trigger from a
traditional test.

This adds the plubming necessary for dwarfgen to generate this section.
The more interesting changes are:
- I've moved emitStringOffsetsTableHeader function from DwarfFile to
  DwarfStringPool, so I can generate the section header more easily from
  the unit test.
- added a new addAttribute overload taking an MCExpr*. This is used to
  generate the DW_AT_str_offsets_base, which links a compile unit to the
  offset table.

I've also added a basic test for reading and writing DW_form_strx forms.

Reviewers: dblaikie, JDevlieghere, probinson

Subscribers: llvm-commits, aprantl

Differential Revision: https://reviews.llvm.org/D49670

llvm-svn: 337910
2018-07-25 11:55:59 +00:00
Jonas Paulsson 374af8070e [SystemZ] Use tablegen loops in SchedModels
NFC changes to make scheduler TableGen files more readable, by using loops
instead of a lot of similar defs with just e.g. a latency value that changes.

https://reviews.llvm.org/D49598
Review: Ulrich Weigand, Javed Abshar

llvm-svn: 337909
2018-07-25 11:42:55 +00:00
Pavel Labath 5457b426f5 Fix PythonString::GetString for >=python-3.7
The return value of PyUnicode_AsUTF8AndSize is now "const char *".

Thanks to Brett Neumeier for testing the patch out on python 3.7.

llvm-svn: 337908
2018-07-25 11:35:28 +00:00
Eric Liu 84bd5db209 [clangd] Use a sigmoid style function for #usages boost in symbol quality.
Summary:
This has a shape to similar logarithm function but grows much slower for
large #usages.

Metrics: https://reviews.llvm.org/P8096

Reviewers: ilya-biryukov

Reviewed By: ilya-biryukov

Subscribers: MaskRay, jkorous, arphaman, cfe-commits, sammccall

Differential Revision: https://reviews.llvm.org/D49780

llvm-svn: 337907
2018-07-25 11:26:35 +00:00
Eric Fiselier a596ea5842 Fix dangling reference in test
llvm-svn: 337906
2018-07-25 11:19:13 +00:00
Eric Fiselier 1f174327d1 Fix diagnostic test to tolerate Clang diagnosing it as well.
Tuple has tests that ensure we diagnose non-lifetime extended
reference bindings inside tuples constructors. As of yesterday,
Clang now does this for us.

Adjust the test to tolerate the new diagnostics, while still
testing that we emit diagnostics of our own. Maybe after this
version of Clang has been adopted by most users we should
remove our diagnostics; but for now more error detection is
better!

llvm-svn: 337905
2018-07-25 11:16:39 +00:00
Florian Hahn 6f5c6adbcd Recommit r333268: [IPSCCP] Use PredicateInfo to propagate facts from cmp instructions.
r337828 resolves a PredicateInfo issue with unnamed types.

Original message:
This patch updates IPSCCP to use PredicateInfo to propagate
facts to true branches predicated by EQ and to false branches
predicated by NE.

As a follow up, we should be able to extend it to also propagate additional
facts about nonnull.

Reviewers: davide, mssimpso, dberlin, efriedma

Reviewed By: davide, dberlin

llvm-svn: 337904
2018-07-25 11:13:40 +00:00
Thomas Preud'homme 768d6ce4a3 Fix PR34170: Crash on inline asm with 64bit output in 32bit GPR
Add support for inline assembly with output operand that do not
naturally go in the register class it is constrained to (eg. double in a
32-bit GPR as in the PR).

llvm-svn: 337903
2018-07-25 11:11:12 +00:00
Paul Semel 0913dcd747 [llvm-objdump] Add dynamic section printing to private-headers option
Differential Revision: https://reviews.llvm.org/D49016

llvm-svn: 337902
2018-07-25 11:09:20 +00:00
Kirill Bobyrev 5e82f05e7a [clangd] Introduce Dex symbol index search tokens
This patch introduces the core building block of the next-generation
Clangd symbol index - Dex. Search tokens are the keys in the inverted
index and represent a characteristic of a specific symbol: examples of
search token types (Token Namespaces) are

* Trigrams -  these are essential for unqualified symbol name fuzzy
search * Scopes for filtering the symbols by the namespace * Paths, e.g.
these can be used to uprank symbols defined close to the edited file

This patch outlines the generic for such token namespaces, but only
implements trigram generation.

The intuition behind trigram generation algorithm is that each extracted
trigram is a valid sequence for Fuzzy Matcher jumps, proposed
implementation utilize existing FuzzyMatcher API for segmentation and
trigram extraction.

However, trigrams generation algorithm for the query string is different
from the previous one: it simply yields sequences of 3 consecutive
lowercased valid characters (letters, digits).

Dex RFC in the mailing list:
http://lists.llvm.org/pipermail/clangd-dev/2018-July/000022.html

The trigram generation techniques are described in detail in the
proposal:
https://docs.google.com/document/d/1C-A6PGT6TynyaX4PXyExNMiGmJ2jL1UwV91Kyx11gOI/edit#heading=h.903u1zon9nkj

Reviewers: sammccall, ioeric, ilya-biryukovA

Subscribers: cfe-commits, klimek, mgorny, MaskRay, jkorous, arphaman

Differential Revision: https://reviews.llvm.org/D49591

llvm-svn: 337901
2018-07-25 10:34:57 +00:00
Eric Fiselier b54393e638 Fix another typo in the FileTimeType docs
llvm-svn: 337900
2018-07-25 10:22:07 +00:00
Krasimir Georgiev cf699ad9ab [clang-format ]Extend IncludeCategories regex documentation
Summary:
Extend the Clang-Format IncludeCategories documentation by adding a link to the supported regular expression standard (POSIX).
And extenting the example with a system header regex.
[[ https://bugs.llvm.org/show_bug.cgi?id=35041 | bug 35041]]

Contributed by WimLeflere!

Reviewers: krasimir, Typz

Reviewed By: krasimir

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D48827

llvm-svn: 337899
2018-07-25 10:21:47 +00:00
Balazs Keri 95baa840c2 [ASTImporter] Add support for import of CXXInheritedCtorInitExpr.
Reviewers: a.sidorin, martong

Reviewed By: martong

Subscribers: rnkovacs, a_sidorin, martong, cfe-commits

Differential Revision: https://reviews.llvm.org/D49293

llvm-svn: 337898
2018-07-25 10:21:06 +00:00
Eric Fiselier f0b379c959 Fix typos, spelling, and grammar in the FileTimeType design docs.
I'm sure I'll discover more mistakes as I go on...

llvm-svn: 337897
2018-07-25 10:17:04 +00:00
Paul Semel 5ce8f1598c [llvm-readobj] Generic hex-dump option
Helpers are available to make this option file format independant. This
patch adds the feature for Wasm file format. It doesn't change the
behavior of the other file format handling.

Differential Revision: https://reviews.llvm.org/D49545

llvm-svn: 337896
2018-07-25 10:04:37 +00:00
Chandler Carruth 4f6481dc81 [x86/SLH] Sink the return hardening into the main block-walk + hardening
code.

This consolidates all our hardening calls, and simplifies the code
a bit. It seems much more clear to handle all of these together.

No functionality changed here.

llvm-svn: 337895
2018-07-25 09:18:48 +00:00
Chandler Carruth 196e719acd [x86/SLH] Improve name and comments for the main hardening function.
This function actually does two things: it traces the predicate state
through each of the basic blocks in the function (as that isn't directly
handled by the SSA updater) *and* it hardens everything necessary in the
block as it goes. These need to be done together so that we have the
currently active predicate state to use at each point of the hardening.

However, this also made obvious that the flag to disable actual
hardening of loads was flawed -- it also disabled tracing the predicate
state across function calls within the body of each block. So this patch
sinks this debugging flag test to correctly guard just the hardening of
loads.

Unless load hardening was disabled, no functionality should change with
tis patch.

llvm-svn: 337894
2018-07-25 09:00:26 +00:00
Simon Atanasyan b524459288 [mips] Replace custom parsing logic for data directives by the `addAliasForDirective`
The target independent AsmParser doesn't recognise .hword, .word, .dword
which are required for Mips. Currently MipsAsmParser recognises these
through dispatch to MipsAsmParser::parseDataDirective. This contains
equivalent logic to AsmParser::parseDirectiveValue. This patch allows
reuse of AsmParser::parseDirectiveValue by making use of
addAliasForDirective to support .hword, .word and .dword.

Original patch provided by Alex Bradbury at D47001 was modified to fix
handling of microMIPS symbols. The `AsmParser::parseDirectiveValue`
calls either `EmitIntValue` or `EmitValue`. In this patch we override
`EmitIntValue` in the `MipsELFStreamer` to clear a pending set of
microMIPS symbols.

Differential revision: https://reviews.llvm.org/D49539

llvm-svn: 337893
2018-07-25 07:07:43 +00:00
Fangrui Song 4eab1ba619 cc1_main: fix -Wsign-compare on FreeBSD
Its __rlim_t is intentionally signed (__int64_t) because of legacy code
that uses -1 for RLIM_INFINITY.

llvm-svn: 337892
2018-07-25 06:57:31 +00:00
Chijun Sima bd5d80d050 [Dominators] Assert if there is modification to DelBB while it is awaiting deletion
Summary:
Previously, passes use
```
DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
DTU.deleteBB(DelBB);
```
to delete a BasicBlock.
But passes which don't have the ability to update DomTree (e.g. tailcallelim, simplifyCFG) cannot recognize a DelBB awaiting deletion and will continue to process this DelBB.
This is a simple approach to notify devs of passes which may use DTU in the future to deal with deleted BasicBlocks under Lazy Strategy correctly.

Reviewers: kuhar, brzycki, dmgreen

Reviewed By: kuhar

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49731

llvm-svn: 337891
2018-07-25 06:18:33 +00:00
Craig Topper dc0e8a601d [X86] Use X86ISD::MUL_IMM instead of ISD::MUL for multiply we intend to be selected to LEA.
This prevents other combines from possibly disturbing it.

llvm-svn: 337890
2018-07-25 05:33:36 +00:00
Craig Topper d9fa8147c4 [X86] Autogenerate complete checks and fix a failure introduced in r337875.
llvm-svn: 337889
2018-07-25 05:22:13 +00:00
Eric Fiselier 84e48004cf Fix bugs in create_directory implementation.
Libc++ was incorrectly reporting an error when the target of create_directory
already exists, but was not a directory. This behavior is not specified
in the most recent standard, which says no error should be reported.

Additionally, libc++ failed to report an error when the attribute directory
path didn't exist or didn't name a directory. This has been fixed as well.

Although it's not clear if we should call status or symlink_status on the
attribute directory. This patch chooses to still call status.

llvm-svn: 337888
2018-07-25 04:46:32 +00:00
JF Bastien 6508929da9 CodeGen: use non-zero memset when possible for automatic variables
Summary:
Right now automatic variables are either initialized with bzero followed by a few stores, or memcpy'd from a synthesized global. We end up encountering a fair amount of code where memcpy of non-zero byte patterns would be better than memcpy from a global because it touches less memory and generates a smaller binary. The optimizer could reason about this, but it's not really worth it when clang already knows.

This code could definitely be more clever but I'm not sure it's worth it. In particular we could track a histogram of bytes seen and figure out (as we do with bzero) if a memset could be followed by a handful of stores. Similarly, we could tune the heuristics for GlobalSize, but using the same as for bzero seems conservatively OK for now.

<rdar://problem/42563091>

Reviewers: dexonsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D49771

llvm-svn: 337887
2018-07-25 04:29:03 +00:00
Eric Fiselier 3b3edcb0b7 Fix missing includes in format_string.hpp helper
llvm-svn: 337886
2018-07-25 04:21:59 +00:00
Marshall Clow c17628fb15 New test support for comparisons. Reviewed as https://reviews.llvm.org/D49773
llvm-svn: 337885
2018-07-25 04:21:21 +00:00
Eric Fiselier 5baf73c354 Make <experimental/filesystem> explicitly require C++11.
Previously the <experimental/filesystem> didn't guard its
contents in any dialect. However, the implementation implicitly
requires at least C++11, and the tests have always been marked
unsupported in C++03. This patch puts a header guard around the
contents to avoid exposing them before C++11.

Additionally, it replaces all of the usages of _NOEXCEPT or
_LIBCPP_CONSTEXPR with the keyword directly, since we can
expect the compiler to implement those by now.

llvm-svn: 337884
2018-07-25 03:41:31 +00:00
Eric Fiselier 52ec6a206f Ensure path::iterator and PathParser share the same enumeration values.
To avoid exposing implementation details, path::iterator and PathParser
both implicitly used the same set of values to represent the state,
but they were defined twice. This could have lead to a mismatch
occuring.

This patch moves all of the parser state values into the filesystem
header and changes PathParser to use those value to avoid this.

llvm-svn: 337883
2018-07-25 03:31:48 +00:00
Tom Stellard 179757ef05 [RegisterBankInfo] Ignore InstrMappings that create impossible to repair operands
Summary:
This is a follow-up to r303043.  In computeMapping(), we need to disqualify an
InstrMapping if it would be impossible to repair one of the registers in the
instruction to match the mapping.

This change is needed in order to be able to define an instruction
mapping for G_SELECT for the AMDGPU target and will be tested
by test/CodeGen/AMDGPU/GlobalISel/regbankselect-select.mir

Reviewers: ab, qcolombet, t.p.northover, dsanders

Reviewed By: qcolombet

Subscribers: tpr, llvm-commits

Differential Revision: https://reviews.llvm.org/D49735

llvm-svn: 337882
2018-07-25 03:08:35 +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
Eric Fiselier d981977d5a Add design docs for upcoming file_time_type change.
In upcoming changes to filesystem I plan to change file_time_type
to use __int128_t as its underlying representation, in order
to allow it to have a range and resolution at least that of
the timespec struct.

There was some pushback against this decision, so I drafted
a document explaining the problems, potential solutions, and
the rational for the decision.

However, it's probably easier to let people read the generated
HTML rather than the raw restructured text. For this reason
I'm commiting the design documents before hand, so they can
be available during any subsequent discussion or code review.

llvm-svn: 337880
2018-07-25 02:53:53 +00:00
Marshall Clow 8f7da2458e Mark <span> as complete
llvm-svn: 337879
2018-07-25 01:55:25 +00:00
Chandler Carruth 7024921c0a [x86/SLH] Teach the x86 speculative load hardening pass to harden
against v1.2 BCBS attacks directly.

Attacks using spectre v1.2 (a subset of BCBS) are described in the paper
here:
https://people.csail.mit.edu/vlk/spectre11.pdf

The core idea is to speculatively store over the address in a vtable,
jumptable, or other target of indirect control flow that will be
subsequently loaded. Speculative execution after such a store can
forward the stored value to subsequent loads, and if called or jumped
to, the speculative execution will be steered to this potentially
attacker controlled address.

Up until now, this could be mitigated by enableing retpolines. However,
that is a relatively expensive technique to mitigate this particular
flavor. Especially because in most cases SLH will have already mitigated
this. To fully mitigate this with SLH, we need to do two core things:
1) Unfold loads from calls and jumps, allowing the loads to be post-load
   hardened.
2) Force hardening of incoming registers even if we didn't end up
   needing to harden the load itself.

The reason we need to do these two things is because hardening calls and
jumps from this particular variant is importantly different from
hardening against leak of secret data. Because the "bad" data here isn't
a secret, but in fact speculatively stored by the attacker, it may be
loaded from any address, regardless of whether it is read-only memory,
mapped memory, or a "hardened" address. The only 100% effective way to
harden these instructions is to harden the their operand itself. But to
the extent possible, we'd like to take advantage of all the other
hardening going on, we just need a fallback in case none of that
happened to cover the particular input to the control transfer
instruction.

For users of SLH, currently they are paing 2% to 6% performance overhead
for retpolines, but this mechanism is expected to be substantially
cheaper. However, it is worth reminding folks that this does not
mitigate all of the things retpolines do -- most notably, variant #2 is
not in *any way* mitigated by this technique. So users of SLH may still
want to enable retpolines, and the implementation is carefuly designed to
gracefully leverage retpolines to avoid the need for further hardening
here when they are enabled.

Differential Revision: https://reviews.llvm.org/D49663

llvm-svn: 337878
2018-07-25 01:51:29 +00:00
Petr Hosek 427b895e2f [CMake] Link static libunwind and libc++abi into libc++ in Fuchsia toolchain
When building libc++ for Fuchsia, we want to distribute shared libc++,
libc++abi and libunwind as separate libraries, but for static versions
we would like to link all of them into libc++ so -lc++ flag has the same
effect whether shared or static library is being used.

Differential Revision: https://reviews.llvm.org/D49628

llvm-svn: 337877
2018-07-25 01:44:22 +00:00