Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
10.0.1 final (aka llvmorg-10.0.1-0-gef32c611aa2).

MFC r360702:

Merge commit 4ca2cad94 from llvm git (by Justin Hibbits):

[PowerPC] Add clang -msvr4-struct-return for 32-bit ELF

Summary:

Change the default ABI to be compatible with GCC. For 32-bit ELF
targets other than Linux, Clang now returns small structs in
registers r3/r4. This affects FreeBSD, NetBSD, OpenBSD. There is no
change for 32-bit Linux, where Clang continues to return all structs
in memory.

Add clang options -maix-struct-return (to return structs in memory)
and -msvr4-struct-return (to return structs in registers) to be
compatible with gcc. These options are only for PPC32; reject them on
PPC64 and other targets. The options are like -fpcc-struct-return and
-freg-struct-return for X86_32, and use similar code.

To actually return a struct in registers, coerce it to an integer of
the same size. LLVM may optimize the code to remove unnecessary
accesses to memory, and will return i32 in r3 or i64 in r3:r4.

Fixes PR#40736

Patch by George Koehler!

Reviewed By: jhibbits, nemanjai
Differential Revision: https://reviews.llvm.org/D73290

Requested by: jhibbits

MFC r361410:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.1-rc1-0-gf79cd71e145 (aka 10.0.1 rc1).

MFC r362235 (by kp):

llvm: Default to -mno-relax on RISC-V

Compiling on a RISC-V system fails with 'relocation R_RISCV_ALIGN
requires unimplemented linker relaxation; recompile with -mno-relax'.

Our default linker (ld.lld) doesn't support relaxation, so default to
no-relax so we don't generate object files the linker can't handle.

Reviewed by: mhorne
Sponsored by: Axiado
Differential Revision: https://reviews.freebsd.org/D25210

MFC r362445:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.0-97-g6f71678ecd2 (not quite 10.0.1 rc2, as more fixes are
still pending).

MFC r362587 (by cem):

Add WITH_CLANG_FORMAT option

clang-format is enabled conditional on either WITH_CLANG_EXTRAS or
WITH_CLANG_FORMAT. Some sources in libclang are build conditional on
either rule, and obviously the clang-format binary itself depends on the
rule.

clang-format could still use a manual page.

Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D25427

MFC r362609:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.0-129-gd24d5c8e308. Getting closer to 10.0.1-rc2.

MFC r362679:

Regenerate ReStructuredText based manpages for llvm-project tools:

* bugpoint.1
* clang.1
* llc.1
* lldb.1
* lli.1
* llvm-ar.1
* llvm-as.1
* llvm-bcanalyzer.1
* llvm-cov.1
* llvm-diff.1
* llvm-dis.1
* llvm-dwarfdump.1
* llvm-extract.1
* llvm-link.1
* llvm-mca.1
* llvm-nm.1
* llvm-pdbutil.1
* llvm-profdata.1
* llvm-symbolizer.1
* llvm-tblgen.1
* opt.1

Add newly generated manpages for:

* llvm-addr2line.1 (this is an alias of llvm-symbolizer)
* llvm-cxxfilt.1
* llvm-objcopy.1
* llvm-ranlib.1 (this is an alias of llvm-ar)

Note that llvm-objdump.1 is an exception, as upstream has both a plain
.1 file, and a .rst variant. These will have to be reconciled upstream
first.

MFC r362680:

Follow-up to r362679, add more entries to OptionalObsoleteFiles.inc

MFC r362719:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.1-rc2-0-g77d76b71d7d.

Also add a few more llvm utilities under WITH_CLANG_EXTRAS:

* llvm-dwp, a utility for merging DWARF 5 Split DWARF .dwo files into
.dwp (DWARF package files)
* llvm-size, a size(1) replacement
* llvm-strings, a strings(1) replacement

MFC r362733:

Remove older llvm-ranlib.1 entry from ObsoleteFiles.inc, as it has
gotten its own manpage now, and should be no longer be removed by "make
delete-old".

MFC r362734:

Fix llvm-strings.1 not installing, this was a copy/paste error.

MFC r363401:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
10.0.1 final (aka llvmorg-10.0.1-0-gef32c611aa2).

There were no changes since rc2, except in the upstream regression
tests, which we do not ship.

Relnotes: yes

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.0-0-gd32170dbd5b (aka 10.0.0 release), and a number of
follow-ups.

MFC r356479 (by bdragon):

[PowerPC] Fix libllvmminimal build when building from powerpc64 ELFv1.

When bootstrapping on powerpc64 ELFv1, it is necessary to use binutils
ld.bfd from ports for the bootstrap, as this is the only modern linker for
ELFv1 host tools.

As binutils ld.bfd is rather strict in its handling of undefined symbols,
it is necessary to pull in Support/Atomic.cpp to avoid an undefined symbol.

Reviewed by: dim, emaste
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D23072

MFC r356930:

Add more Subversion mergeinfo bootstrap information, to hopefully
increase the probability of merging in vendor changes.

MFC r358408 (by brooks):

Merge commit 7214f7a79 from llvm git (by Sam Elliott):

[RISCV] Lower llvm.trap and llvm.debugtrap

Summary:
Until this commit, these have lowered to a call to abort().

`llvm.trap()` now lowers to `unimp`, which should trap on all systems.

`llvm.debugtrap()` now lowers to `ebreak`, which is exactly what this
instruction is for.

Reviewers: asb, luismarques

Reviewed By: asb

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69390

This fixes miscompilation resulting in linking failures with
INVARIANTS disabled.

Reviewed by: dim
Differential Revision: https://reviews.freebsd.org/D23857

MFC r358851:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
10.0.0-rc3 c290cb61fdc.

Release notes for llvm, clang, lld and libc++ 10.0.0 will become
available here:

https://releases.llvm.org/10.0.0/docs/ReleaseNotes.html
https://releases.llvm.org/10.0.0/tools/clang/docs/ReleaseNotes.html
https://releases.llvm.org/10.0.0/tools/lld/docs/ReleaseNotes.html
https://releases.llvm.org/10.0.0/projects/libcxx/docs/ReleaseNotes.html

PR: 244251

MFC r358854:

Add one additional file to libllvmminimal, to help the ppc64 bootstrap.

Reported by: bdragon
PR: 244251

MFC r358857:

Move another file in libllvm from sources required for world, to sources
required for bootstrap, as the PowerPC builds need this.

Reported by: bdragon
PR: 244251

MFC r359082:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.0-rc4-5-g52c365aa9ca. The actual release should follow Real
Soon Now.

PR: 244251

MFC r359084:

Merge commit 00925aadb from llvm git (by Fangrui Song):

[ELF][PPC32] Fix canonical PLTs when the order does not match the PLT order

Reviewed By: Bdragon28

Differential Revision: https://reviews.llvm.org/D75394

This is needed to fix miscompiled canonical PLTs on ppc32/lld10.

Requested by: bdragon
Differential Revision: https://reviews.freebsd.org/D24109

MFC r359085:

Merge commit 315f8a55f from llvm git (by Fangrui Song):

[ELF][PPC32] Don't report "relocation refers to a discarded section"
for .got2

Similar to D63182 [ELF][PPC64] Don't report "relocation refers to a
discarded section" for .toc

Reviewed By: Bdragon28

Differential Revision: https://reviews.llvm.org/D75419

This is needed to fix compile errors when building for ppc32/lld10.

Requested by: bdragon
Differential Revision: https://reviews.freebsd.org/D24110

MFC r359086:

Merge commit b8ebc11f0 from llvm git (by Sanjay Patel):

[EarlyCSE] avoid crashing when detecting min/max/abs patterns (PR41083)

As discussed in PR41083:
https://bugs.llvm.org/show_bug.cgi?id=41083
...we can assert/crash in EarlyCSE using the current hashing scheme
and instructions with flags.

ValueTracking's matchSelectPattern() may rely on overflow (nsw, etc)
or other flags when detecting patterns such as min/max/abs composed
of compare+select. But the value numbering / hashing mechanism used
by EarlyCSE intersects those flags to allow more CSE.

Several alternatives to solve this are discussed in the bug report.
This patch avoids the issue by doing simple matching of min/max/abs
patterns that never requires instruction flags. We give up some CSE
power because of that, but that is not expected to result in much
actual performance difference because InstCombine will canonicalize
these patterns when possible. It even has this comment for abs/nabs:

/// Canonicalize all these variants to 1 pattern.
/// This makes CSE more likely.

(And this patch adds PhaseOrdering tests to verify that the expected
transforms are still happening in the standard optimization
pipelines.

I left this code to use ValueTracking's "flavor" enum values, so we
don't have to change the callers' code. If we decide to go back to
using the ValueTracking call (by changing the hashing algorithm
instead), it should be obvious how to replace this chunk.

Differential Revision: https://reviews.llvm.org/D74285

This fixes an assertion when building the math/gsl port on PowerPC64.

Requested by: pkubja

MFC r359087:

Merge commit 585a3cc31 from llvm git (by me):

Fix -Wdeprecated-copy-dtor and -Wdeprecated-dynamic-exception-spec
warnings.

Summary:
The former are like:

libcxx/include/typeinfo:322:11: warning: definition of implicit copy
constructor for 'bad_cast' is deprecated because it has a
user-declared destructor [-Wdeprecated-copy-dtor]
virtual ~bad_cast() _NOEXCEPT;
^
libcxx/include/typeinfo:344:11: note: in implicit copy constructor
for 'std::bad_cast' first required here
throw bad_cast();
^

Fix these by adding an explicitly defaulted copy constructor.

The latter are like:

libcxx/include/codecvt:105:37: warning: dynamic exception
specifications are deprecated [-Wdeprecated-dynamic-exception-spec]
virtual int do_encoding() const throw();
^~~~~~~

Fix these by using the _NOEXCEPT macro instead.

Reviewers: EricWF, mclow.lists, ldionne, #libc

Reviewed By: EricWF, #libc

Subscribers: dexonsmith, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D76150

This is because we use -Wsystem-headers during buildworld, and the two
warnings above are now triggered by default with clang 10, preventing
most C++ code from compiling without NO_WERROR.

Requested by: brooks
Differential Revision: https://reviews.freebsd.org/D24049

MFC r359333:

Merge commit f0990e104 from llvm git (by Justin Hibbits):

[PowerPC]: e500 target can't use lwsync, use msync instead

The e500 core has a silicon bug that triggers an illegal instruction
program trap on any sync other than msync. Other cores will typically
ignore illegal sync types, and the documentation even implies that
the 'illegal' bits are ignored.

Address this hardware deficiency by only using msync, like the PPC440.

Differential Revision: https://reviews.llvm.org/D76614

Requested by: jhibbits

MFC r359334:

Merge commit 459e8e948 from llvm git (by Justin Hibbits):

[PowerPC]: Don't allow r0 as a target for LD_GOT_TPREL_L/32

Summary:
The linker is free to relax this (relocation R_PPC_GOT_TPREL16)
against R_PPC_TLS, if it sees fit (initial exec to local exec). If r0
is used, this can generate execution-invalid code (converts to 'addi
%rX, %r0, FOO, which translates in PPC-lingo to li %rX, FOO). Forbid
this instead.

This fixes static binaries using locales on FreeBSD/powerpc (tested
on FreeBSD/powerpcspe).

Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D76662

Requested by: jhibbits

MFC r359338:

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.0-0-gd32170dbd5b (aka 10.0.0 release).

PR: 244251

MFC r359506 (by emaste):

lldb: stop excluding bindings/ subdir

With liblua in the tree we should be able to enable lldb's lua
scripting. We'll need the files in bindings/, so start by allowing them
to come in with the next import.

Approved by: dim
Sponsored by: The FreeBSD Foundation

MFC r359578:

Merge once more from ^/vendor/llvm-project/release-10.x, to get the
lldb/bindings directory, which will be used to provide lua bindings for
lldb.

Requested by: emaste

MFC r359826:

Merge commit 30588a739 from llvm git (by Erich Keane):

Make target features check work with ctor and dtor-

The problem was reported in PR45468, applying target features to an
always_inline constructor/destructor runs afoul of GlobalDecl
construction assert when checking for target-feature compatibility.

The core problem is fixed by using the version of the check that
takes a FunctionDecl rather than the GlobalDecl. However, while
writing the test, I discovered that source locations weren't properly
set for this check on ctors/dtors. This patch also fixes constructors
and CALLED destructors.

Unfortunately, it doesn't seem too possible to get a meaningful
source location for a 'cleanup' destructor, so those are still
'frontend' level errors unfortunately. A fixme was added to the test
to cover that situation.

This should fix 'Assertion failed: (!isa<CXXConstructorDecl>(D) && "Use
other ctor with ctor decls!"), function Init, file
/usr/src/contrib/llvm-project/clang/include/clang/AST/GlobalDecl.h, line
45' when compiling the security/botan2 port.

PR: 245550

MFC r359981:

Revert commit a9ad65a2b from llvm git (by Nemanja Ivanovic):

[PowerPC] Change default for unaligned FP access for older subtargets

This is a fix for https://bugs.llvm.org/show_bug.cgi?id=40554

Some CPU's trap to the kernel on unaligned floating point access and
there are kernels that do not handle the interrupt. The program then
fails with a SIGBUS according to the PR. This just switches the
default for unaligned access to only allow it on recent server CPUs
that are known to allow this.

Differential revision: https://reviews.llvm.org/D71954

This upstream commit causes a compiler hang when building certain ports
(e.g. security/nss, multimedia/x264) for powerpc64. The hang has been
reported in https://bugs.llvm.org/show_bug.cgi?id=45186, but in the mean
time it is more convenient to revert the commit.

Requested by: jhibbits

MFC r359994:

Revert commit b6cf400aa fro llvm git (by Nemanja Ivanovic):

Fix bots after a9ad65a2b34f

In the last commit, I neglected to initialize the new subtarget
feature I added which caused failures on a few bots. This should fix
that.

This unbreaks the build after r359981, which reverted upstream commit
a9ad65a2b34f.

Reported by: jhibbits (and jenkins :)

MFC r360129:

Merge commit ce5173c0e from llvm git (by Reid Kleckner):

Use FinishThunk to finish musttail thunks

FinishThunk, and the invariant of setting and then unsetting
CurCodeDecl, was added in 7f416cc42638 (2015). The invariant didn't
exist when I added this musttail codepath in ab2090d10765 (2014).
Recently in 28328c3771, I started using this codepath on non-Windows
platforms, and users reported problems during release testing
(PR44987).

The issue was already present for users of EH on i686-windows-msvc,
so I added a test for that case as well.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D76444

This should fix 'Assertion failed: (!empty() && "popping exception stack
when not empty"), function popTerminate, file
/usr/src/contrib/llvm-project/clang/lib/CodeGen/CGCleanup.h, line 583'
when building the net-p2p/libtorrent-rasterbar

PR: 244830
Reported by: jbeich, yuri

MFC r360134:

Merge commit 64b31d96d from llvm git (by Nemanja Ivanovic):

[PowerPC] Do not attempt to reuse load for 64-bit FP_TO_UINT without
FPCVT

We call the function that attempts to reuse the conversion without
checking whether the target matches the constraints that the callee
expects. This patch adds the check prior to the call.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=43976

Differential revision: https://reviews.llvm.org/D77564

This should fix 'Assertion failed: ((Op.getOpcode() == ISD::FP_TO_SINT
|| Subtarget.hasFPCVT()) && "i64 FP_TO_UINT is supported only with
FPCVT"), function LowerFP_TO_INTForReuse, file
/usr/src/contrib/llvm/lib/Target/PowerPC/PPCISelLowering.cpp, line 7276'
when building the devel/libslang2 port (and a few others) for PowerPC64.

Requested by: pkubaj

MFC r360350:

Tentatively apply https://reviews.llvm.org/D78877 (by Dave Green):

[ARM] Only produce qadd8b under hasV6Ops

When compiling for a arm5te cpu from clang, the +dsp attribute is
set. This meant we could try and generate qadd8 instructions where we
would end up having no pattern. I've changed the condition here to be
hasV6Ops && hasDSP, which is what other parts of ARMISelLowering seem
to use for similar instructions.

Fixed PR45677.

This fixes "fatal error: error in backend: Cannot select: t37: i32 =
ARMISD::QADD8b t43, t44" when compiling sys/dev/sound/pcm/feeder_mixer.c
for armv5. For some reason we do not encounter this on head, but this
error popped up while building universes for stable/12.

MFC r360697:

In r358396 I merged llvm upstream commit 2e24219d3, which fixed "error:
unsupported relocation on symbol" when assembling arm 'adr' pseudo
instructions. However, the upstream commit did not take big-endian arm
into account.

Applying the same changes to the big-endian handling is straightforward,
thanks to Andrew Turner and Peter Smith for the hint. This will also be
submitted upstream.

MFC r355940:

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
9.0.0 final release r372316.

Release notes for llvm, clang, lld and libc++ 9.0.0 are available here:

https://releases.llvm.org/9.0.0/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/tools/clang/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/tools/lld/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/projects/libcxx/docs/ReleaseNotes.html

PR: 240629
MFC after: 1 month

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt, libc++,
libunwind and openmp to the upstream release_80 branch r363030
(effectively, 8.0.1 rc2). The 8.0.1 release should follow this within a
week or so.

MFC after: 2 weeks

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
the upstream release_80 branch r355313 (effectively, 8.0.0 rc3). The
release will follow very soon, but no more functional changes are
expected.

Release notes for llvm, clang and lld 8.0.0 will soon be available here:
<https://releases.llvm.org/8.0.0/docs/ReleaseNotes.html>
<https://releases.llvm.org/8.0.0/tools/clang/docs/ReleaseNotes.html>
<https://releases.llvm.org/8.0.0/tools/lld/docs/ReleaseNotes.html>

PR: 236062
Relnotes: yes
MFC after: 1 month

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
the upstream release_70 branch r348686 (effectively, 7.0.1 rc3). The
release will follow very soon, but no more functional changes are
expected.

Release notes for llvm, clang and lld 7.0.0 are available here:
<http://releases.llvm.org/7.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/7.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/7.0.0/tools/lld/docs/ReleaseNotes.html>

PR: 230240, 230355
Relnotes: yes
MFC after: 2 months

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.1 release (upstream r335540).

Relnotes: yes
MFC after: 2 weeks

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r324090).

This introduces retpoline support, with the -mretpoline flag. The
upstream initial commit message (r323155 by Chandler Carruth) contains
quite a bit of explanation. Quoting:

Introduce the "retpoline" x86 mitigation technique for variant #2 of
the speculative execution vulnerabilities disclosed today,
specifically identified by CVE-2017-5715, "Branch Target Injection",
and is one of the two halves to Spectre.

Summary:
First, we need to explain the core of the vulnerability. Note that
this is a very incomplete description, please see the Project Zero
blog post for details:
https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html

The basis for branch target injection is to direct speculative
execution of the processor to some "gadget" of executable code by
poisoning the prediction of indirect branches with the address of
that gadget. The gadget in turn contains an operation that provides a
side channel for reading data. Most commonly, this will look like a
load of secret data followed by a branch on the loaded value and then
a load of some predictable cache line. The attacker then uses timing
of the processors cache to determine which direction the branch took
*in the speculative execution*, and in turn what one bit of the
loaded value was. Due to the nature of these timing side channels and
the branch predictor on Intel processors, this allows an attacker to
leak data only accessible to a privileged domain (like the kernel)
back into an unprivileged domain.

The goal is simple: avoid generating code which contains an indirect
branch that could have its prediction poisoned by an attacker. In
many cases, the compiler can simply use directed conditional branches
and a small search tree. LLVM already has support for lowering
switches in this way and the first step of this patch is to disable
jump-table lowering of switches and introduce a pass to rewrite
explicit indirectbr sequences into a switch over integers.

However, there is no fully general alternative to indirect calls. We
introduce a new construct we call a "retpoline" to implement indirect
calls in a non-speculatable way. It can be thought of loosely as a
trampoline for indirect calls which uses the RET instruction on x86.
Further, we arrange for a specific call->ret sequence which ensures
the processor predicts the return to go to a controlled, known
location. The retpoline then "smashes" the return address pushed onto
the stack by the call with the desired target of the original
indirect call. The result is a predicted return to the next
instruction after a call (which can be used to trap speculative
execution within an infinite loop) and an actual indirect branch to
an arbitrary address.

On 64-bit x86 ABIs, this is especially easily done in the compiler by
using a guaranteed scratch register to pass the target into this
device. For 32-bit ABIs there isn't a guaranteed scratch register
and so several different retpoline variants are introduced to use a
scratch register if one is available in the calling convention and to
otherwise use direct stack push/pop sequences to pass the target
address.

This "retpoline" mitigation is fully described in the following blog
post: https://support.google.com/faqs/answer/7625886

We also support a target feature that disables emission of the
retpoline thunk by the compiler to allow for custom thunks if users
want them. These are particularly useful in environments like
kernels that routinely do hot-patching on boot and want to hot-patch
their thunk to different code sequences. They can write this custom
thunk and use `-mretpoline-external-thunk` *in addition* to
`-mretpoline`. In this case, on x86-64 thu thunk names must be:
```
__llvm_external_retpoline_r11
```
or on 32-bit:
```
__llvm_external_retpoline_eax
__llvm_external_retpoline_ecx
__llvm_external_retpoline_edx
__llvm_external_retpoline_push
```
And the target of the retpoline is passed in the named register, or in
the case of the `push` suffix on the top of the stack via a `pushl`
instruction.

There is one other important source of indirect branches in x86 ELF
binaries: the PLT. These patches also include support for LLD to
generate PLT entries that perform a retpoline-style indirection.

The only other indirect branches remaining that we are aware of are
from precompiled runtimes (such as crt0.o and similar). The ones we
have found are not really attackable, and so we have not focused on
them here, but eventually these runtimes should also be replicated for
retpoline-ed configurations for completeness.

For kernels or other freestanding or fully static executables, the
compiler switch `-mretpoline` is sufficient to fully mitigate this
particular attack. For dynamic executables, you must compile *all*
libraries with `-mretpoline` and additionally link the dynamic
executable and all shared libraries with LLD and pass `-z
retpolineplt` (or use similar functionality from some other linker).
We strongly recommend also using `-z now` as non-lazy binding allows
the retpoline-mitigated PLT to be substantially smaller.

When manually apply similar transformations to `-mretpoline` to the
Linux kernel we observed very small performance hits to applications
running typic al workloads, and relatively minor hits (approximately
2%) even for extremely syscall-heavy applications. This is largely
due to the small number of indirect branches that occur in
performance sensitive paths of the kernel.

When using these patches on statically linked applications,
especially C++ applications, you should expect to see a much more
dramatic performance hit. For microbenchmarks that are switch,
indirect-, or virtual-call heavy we have seen overheads ranging from
10% to 50%.

However, real-world workloads exhibit substantially lower performance
impact. Notably, techniques such as PGO and ThinLTO dramatically
reduce the impact of hot indirect calls (by speculatively promoting
them to direct calls) and allow optimized search trees to be used to
lower switches. If you need to deploy these techniques in C++
applications, we *strongly* recommend that you ensure all hot call
targets are statically linked (avoiding PLT indirection) and use both
PGO and ThinLTO. Well tuned servers using all of these techniques saw
5% - 10% overhead from the use of retpoline.

We will add detailed documentation covering these components in
subsequent patches, but wanted to make the core functionality
available as soon as possible. Happy for more code review, but we'd
really like to get these patches landed and backported ASAP for
obvious reasons. We're planning to backport this to both 6.0 and 5.0
release streams and get a 5.0 release with just this cherry picked
ASAP for distros and vendors.

This patch is the work of a number of people over the past month:
Eric, Reid, Rui, and myself. I'm mailing it out as a single commit
due to the time sensitive nature of landing this and the need to
backport it. Huge thanks to everyone who helped out here, and
everyone at Intel who helped out in discussions about how to craft
this. Also, credit goes to Paul Turner (at Google, but not an LLVM
contributor) for much of the underlying retpoline design.

Reviewers: echristo, rnk, ruiu, craig.topper, DavidKreitzer

Subscribers: sanjoy, emaste, mcrosier, mgorny, mehdi_amini, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D41723

MFC after: 3 months
X-MFC-With: r327952
PR: 224669

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r321788). Upstream has branched for the
6.0.0 release, which should be in about 6 weeks. Please report bugs and
regressions, so we can get them into the release.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

MFC after: 3 months

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
5.0.0 (trunk r308421). Upstream has branched for the 5.0.0 release,
which should be in about a month. Please report bugs and regressions,
so we can get them into the release.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

MFC after: 2 months

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
4.0.0 (branches/release_40 296509). The release will follow soon.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Also note that as of 4.0.0, lld should be able to link the base system
on amd64 and aarch64. See the WITH_LLD_IS_LLD setting in src.conf(5).
Though please be aware that this is work in progress.

Release notes for llvm, clang and lld will be available here:
<http://releases.llvm.org/4.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/lld/docs/ReleaseNotes.html>

Thanks to Ed Maste, Jan Beich, Antoine Brodin and Eric Fiselier for
their help.

Relnotes: yes
Exp-run: antoine
PR: 215969, 216008
MFC after: 1 month

Upgrade our copies of clang, llvm, lldb, compiler-rt and libc++ to 3.9.0
release, and add lld 3.9.0. Also completely revamp the build system for
clang, llvm, lldb and their related tools.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Release notes for llvm, clang and lld are available here:
<http://llvm.org/releases/3.9.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.9.0/tools/clang/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.9.0/tools/lld/docs/ReleaseNotes.html>

Thanks to Ed Maste, Bryan Drewery, Andrew Turner, Antoine Brodin and Jan
Beich for their help.

Relnotes: yes
MFC after: 1 month

Upgrade our copies of clang, llvm, lldb and compiler-rt to 3.8.0
release.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Release notes for llvm and clang will soon be available here:
<http://llvm.org/releases/3.8.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.8.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste, Roman Divacky, Davide Italiano and Antoine Brodin
for their help.

Relnotes: yes

Upgrade our copies of clang, llvm, lldb, compiler-rt and libc++ to 3.7.0
release.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.7.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.7.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste, Andrew Turner and Antoine Brodin for their help.

Exp-run: antoine
Relnotes: yes

Upgrade our copy of clang, llvm and lldb to 3.6.0 release.

Please note that from 3.5.0 onwards, clang/llvm/lldb require C++11
support to build; see UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.6.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.6.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste for the lldb part of this upgrade.

Exp-run: antoine

Back out r278349 and r278350 for now, since this apparently blows up the
kernel build in sys/dev/hptmv/hptproc.c for some people.

Reported by: sbruno, Matthew Fuller <fullermd@over-yonder.net>

Pull in r224884 from upstream llvm trunk (by Keno Fischer):

[FastIsel][X86] Fix invalid register replacement for bool args

Summary:
Consider the following IR:

%3 = load i8* undef
%4 = trunc i8 %3 to i1
%5 = call %jl_value_t.0* @foo(..., i1 %4, ...)
ret %jl_value_t.0* %5

Bools (that are the result of direct truncs) are lowered as whatever
the argument to the trunc was and a "and 1", causing the part of the
MBB responsible for this argument to look something like this:

%vreg8<def,tied1> = AND8ri %vreg7<kill,tied0>, 1, %EFLAGS<imp-def>; GR8:%vreg8,%vreg7

Later, when the load is lowered, it will insert

%vreg15<def> = MOV8rm %vreg14, 1, %noreg, 0, %noreg; mem:LD1[undef] GR8:%vreg15 GR64:%vreg14

but remember to (at the end of isel) replace vreg7 by vreg15. Now for
the bug. In fast isel lowering, we mistakenly mark vreg8 as the result
of the load instead of the trunc. This adds a fixup to have
vreg8 replaced by whatever the result of the load is as well, so
we end up with

%vreg15<def,tied1> = AND8ri %vreg15<kill,tied0>, 1, %EFLAGS<imp-def>; GR8:%vreg15

which is an SSA violation and causes problems later down the road.

This fixes PR21557.

Test Plan: Test test case from PR21557 is added to the test suite.

Reviewers: ributzka

Reviewed By: ributzka

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6245

This fixes a possible assertion failure when compiling toolbox.cxx from
LibreOffice 4.3.5.

Reported by: kwm

Upgrade our copy of clang and llvm to 3.5.1 release. This is a bugfix
only release, no new features have been added.

Please note that this version requires C++11 support to build; see
UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.5.1/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.5.1/tools/clang/docs/ReleaseNotes.html>

MFC after: 1 month
X-MFC-With: 276479

Upgrade our copy of clang, llvm and lldb to 3.5.0 release.

Please note that this version now requires C++11 support to build; see
UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.5.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.5.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste, Roman Divacky, Andrew Turner, Justin Hibbits and
Antoine Brodin for their invaluable help with this import.

Approved by: portmgr (antoine)
MFC after: 1 month

Upgrade our copy of llvm/clang to 3.4 release. This version supports
all of the features in the current working draft of the upcoming C++
standard, provisionally named C++1y.

The code generator's performance is greatly increased, and the loop
auto-vectorizer is now enabled at -Os and -O2 in addition to -O3. The
PowerPC backend has made several major improvements to code generation
quality and compile time, and the X86, SPARC, ARM32, Aarch64 and SystemZ
backends have all seen major feature work.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.4/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>

MFC after: 1 month

Pull in r189644 from upstream llvm trunk:

Add ms_abi and sysv_abi attribute handling.

Based on a patch by Benno Rice!

This will help to develop EFI support.

Approved by: re (kib)
Verified by: benno
MFC after: 1 week

Upgrade our copy of llvm/clang to 3.3 release.

Release notes are still in the works, these will follow soon.

MFC after: 1 month

Upgrade our copy of llvm/clang to trunk r178860, in preparation of the
upcoming 3.3 release (branching and freezing expected in a few weeks).

Preliminary release notes can be found at the usual location:
<http://llvm.org/docs/ReleaseNotes.html>

An MFC is planned once the actual 3.3 release is finished.

Upgrade our copy of llvm/clang to r168974, from upstream's release_32
branch. This is effectively llvm/clang 3.2 RC2; the 3.2 release is
coming soon.

Upgrade our copy of llvm/clang to trunk r162107. With thanks to
Benjamin Kramer and Joerg Sonnenberger for their input and fixes.

Upgrade our copy of llvm/clang to trunk r154661, in preparation of the
upcoming 3.1 release (expected in a few weeks). Preliminary release
notes can be found at: <http://llvm.org/docs/ReleaseNotes.html>

MFC after: 2 weeks

Upgrade our copy of llvm/clang to r142614, from upstream's release_30
branch. This brings us very close to the 3.0 release, which is expected
in a week or two.

MFC after: 1 week

Upgrade our copy of llvm/clang to r135360, from upstream's trunk.

Upgrade our copy of llvm/clang to r132879, from upstream's trunk.

Upgrade our copy of llvm/clang to r130700, from upstream's trunk.

Update llvm/clang to trunk r126547.

There are several bugfixes in this update, but the most important one is
to ensure __start_ and __stop_ symbols for linker sets and kernel module
metadata are always emitted in object files:

http://llvm.org/bugs/show_bug.cgi?id=9292

Before this fix, if you compiled kernel modules with clang, they would
not be properly processed by kldxref, and if they had any dependencies,
the kernel would fail to load those. Another problem occurred when
attempting to mount a tmpfs filesystem, which would result in 'operation
not supported by device'.

Upgrade our copy of llvm/clang to r126079, from upstream's trunk.

This contains many improvements, primarily better C++ support, an
integrated assembler for x86 and support for -pg.

Upgrade our Clang in base to r114020, from upstream's release_28 branch.

Approved-by: rpaulo (mentor)

Upgrade our Clang in base to r108428.

This commit merges the latest LLVM sources from the vendor space. It
also updates the build glue to match the new sources. Clang's version
number is changed to match LLVM's, which means /usr/include/clang/2.0
has been renamed to /usr/include/clang/2.8.

Obtained from: projects/clangbsd

Import LLVM/clang from vendor stripped of docs/ test/ website/ www/ examples/
in llvm/ and/or llvm/contrib/clang/ respectively.

Approved by: ed (mentor)
Approved by: core

Update LLVM to r104832.

Update LLVM to r103004.

Update LLVM to r100520.

Update LLVM to r100181.

Update LLVM to r99115.

Update LLVM to r98631.

Update LLVM to r97873.

Update LLVM to 97654.

Update LLVM to r96341.

Update LLVM to r94309.

Update LLVM to 93512.

Update LLVM to r89205.

Update llvm to r84119.

Import LLVM 74788.

Import LLVM r74383.

Import LLVM r73340.

Import LLVM, at r72770.

This should fix LLVM PR4225.

Import LLVM, at r72732.