Pass and return _Float16 as if it were an int or float for ARM, but with the
top 16 bits unspecified, similarly like we already do for __fp16.

We will implement proper half-precision function argument lowering in the ARM
backend soon, but want to use this workaround in the mean time.

Differential Revision: https://reviews.llvm.org/D42318

llvm-svn: 323185

- Alter abs for micromips to have both AFGR64 and FGR64
  variants, same as sqrt
- Remove sqrt and abs from MicroMips32r6InstrInfo.td,
  use micromips FGR64 variants
- Restrict non-micromips abs/sqrt with NotInMicroMips
  predicate

Differential revision: https://reviews.llvm.org/D41439

llvm-svn: 323184

Summary:
This patch is adding remark messages to the LoopVersioning LICM pass, 
which will be useful for optimization remark emitter (ORE) infrastructure.

Patch by: Deepak Porwal

Reviewers: anemet, ashutosh.nema, eastig

Subscribers: eastig, vivekvpandya, fhahn, llvm-commits
llvm-svn: 323183

llvm-svn: 323182

Summary:
It's possible to hit an unaligned memory read when reading `source_length` as the `data` array is only aligned with 2 bytes (it's actually a UTF16 array). This patch memcpy's `source_length` into a local variable to prevent this:

```
MinidumpTypes.cpp:49:23: runtime error: load of misaligned address 0x7f0f4792692a for type 'const uint32_t' (aka 'const unsigned int'), which requires 4 byte alignment
```

Reviewers: dvlahovski, zturner, davide

Reviewed By: davide

Subscribers: davide, lldb-commits

Differential Revision: https://reviews.llvm.org/D42348

llvm-svn: 323181

llvm-svn: 323180

The LLVM IR section of a MIR document can start with "--- |" rather
than just "---", because "|" is a sigil for a freeform document in
YAML. We need to handle this so that we don't try to add check lines
to the LLVM IR functions in a MIR file.

llvm-svn: 323178

"the the" -> "the"

llvm-svn: 323177

"the the" -> "the"

llvm-svn: 323176

Summary:
If we can match as a zero extend there's no need to flip the order to get an encoding benefit. As movzx is 3 bytes with independent source/dest registers. The shortest 'and' we could make is also 3 bytes unless we get lucky in the register allocator and its on AL/AX/EAX which have a 2 byte encoding.

This patch was more impressive before r322957 went in. It removed some of the same Ands that got deleted by that patch.

Reviewers: spatel, RKSimon

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D42313

llvm-svn: 323175

Some of the NOREX instructions are used in 32-bit mode making this printing confusing. It also doesn't provide a lot of value since you can see the h-register being used by the instruction.

llvm-svn: 323174

Add missing patterns for inserting v1i1 into a zero vector. Use insert_subvector to zero upper bits before inserting an element into a vXi1 vector. Replace kshift based isel pattern with insert_subvector based pattern now that code that caused the pattern has been fixed to emit insert_subvector.

llvm-svn: 323173

It includes 32 bit values and this matches both gold and bfd.

llvm-svn: 323172

* Previously part of https://reviews.llvm.org/D41622.

llvm-svn: 323171

This is an MSVC standard library extension. It seems like a reasonable
enough extension to me because wchar_t* is the native format for
filenames on that platform.

Differential Revision: https://reviews.llvm.org/D42225

llvm-svn: 323170

This allows us to avoid polluting the namespace of users of <thread>
with the definitions in windows.h.

Differential Revision: https://reviews.llvm.org/D42214

llvm-svn: 323169

TABLE relocations now store the function that is being refered
to indirectly.

See rL323165.

Also extend the call-indirect.ll a little.

Based on a patch by Nicholas Wilson!

llvm-svn: 323168

Using a new extension point in the new PM, register GCOV at the start of
the pipeline rather than the end.

llvm-svn: 323167

This applies to most pipelines except the LTO and ThinLTO backend
actions - it is for use at the beginning of the overall pipeline.

This extension point will be used to add the GCOV pass when enabled in
Clang.

llvm-svn: 323166

Relocations of type R_WEBASSEMBLY_TABLE_INDEX represent places
where the table index for a given function is needed.  While the
value stored in this location is a table index, the index in
the relocation entry itself is a function index (the index of
the function which is to be called indirectly).

This is how is was spec'd originally but the LLVM implementation
didn't do this.  This makes things a little simpler in the linker
since the table in the input file can essentially be ignored that
the output table can be created purely based on these relocations.

Patch by Nicholas Wilson!

Differential Revision: https://reviews.llvm.org/D42080

llvm-svn: 323165

Summary:
This detects when an import library is about to be overwritten with a
newly built one with the same contents, and keeps the old library
instead. The use case for this is to avoid needlessly rebuilding
targets that depend on the import library in build systems that rely
on timestamps to determine whether a target requires rebuilding.

This feature was requested in PR35917.

Reviewers: rnk, ruiu, zturner, pcc

Reviewed By: ruiu

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D42326

llvm-svn: 323164

building method override tables for CXXMethodDecls in 
DWARFASTParserClang::CompleteTypeFromDWARF.

C++ virtual method calls in LLDB expressions may fail if the override table for
the method being called is not correct as IRGen will produce references to the
wrong (or a missing) vtable entry.

This patch does not fix calls to virtual methods with covariant return types as
it mistakenly treats these as overloads, rather than overrides. This will be
addressed in a future patch.

Review: https://reviews.llvm.org/D41997

Partially fixes <rdar://problem/14205774>

llvm-svn: 323163

Summary:
One test-case uses a wrong operation (should be subtraction).
Second test-case should declare a global variables before a tested one
in order to guarantee we will find a red-zone.

Reviewers: kcc, jakubjelinek, alekseyshl

Reviewed By: alekseyshl

Subscribers: kubamracek

Differential Revision: https://reviews.llvm.org/D41481

llvm-svn: 323162

The original change was made based on a misunderstanding that
-DCMAKE_BUILD_TYPE=RelWithDebugInfo would produce the same executable
as -DCMAKE_BUILD_TYPE=Release modulo debug info. Turned out that's not
true -- it at least disables some optimizations such as function inlining.

llvm-svn: 323161

llvm-svn: 323160

llvm-svn: 323159

Adds AST matcher for a FunctionDecl that has a trailing return type.

Differential Revision: https://reviews.llvm.org/D42273

llvm-svn: 323158

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D42213

llvm-svn: 323157

When a function taking transparent union is declared as taking one of
union members earlier in the translation unit, clang would hit an
"Invalid cast" assertion during EmitFunctionProlog. This case
corresponds to function f1 in test/CodeGen/transparent-union-redecl.c.
We decided to cast i32 to union because after merging function
declarations function parameter type becomes int,
CGFunctionInfo::ArgInfo type matches with ABIArgInfo type, so we decide
it is a trivial case. But these types should also be castable to
parameter declaration type which is not the case here.

Now the fix is in converting from ABIArgInfo type to VarDecl type and using
argument demotion when necessary.

Additional tests in Sema/transparent-union.c capture current behavior and make
sure there are no regressions.

rdar://problem/34949329

Reviewers: rjmccall, rafael

Reviewed By: rjmccall

Subscribers: aemerson, cfe-commits, kristof.beyls, ahatanak

Differential Revision: https://reviews.llvm.org/D41311

llvm-svn: 323156

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 typical 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

llvm-svn: 323155

This was added to mimic ELF, but maintaining it has cost
and we currently don't have any use for it outside of the
test code.

Differential Revision: https://reviews.llvm.org/D42324

llvm-svn: 323154

- Change inserted add ( V_ADD_{I|U}32_e32 ) to _e64 version ( V_ADD_{I|U}32_e64 ) so that the add uses a vreg for the carry; this prevents inserted v_add from killing VCC; the _e64 version doesn't accept a literal in its encoding, so we need to introduce a mov instr as well to get the imm into a register.
- Change pass name to "SI Load Store Optimizer"; this removes the '/', which complicates scripts.

Differential Revision: https://reviews.llvm.org/D42124

llvm-svn: 323153

Another batch of P0202 constepr algirithms. remove/remove_if/remove_copy/remove_copy_if/reverse_copy, and tests (commented out) for rotate_copy, because that depends on std::copy

llvm-svn: 323152

llvm-svn: 323149

Also avoid printing a 'void' return type for constructor expressions.

llvm-svn: 323148

llvm-svn: 323147

The check (inside StackHintGeneratorForSymbol::getMessage)
if (!N)
    return getMessageForSymbolNotFound()
is moved to the beginning of the function.

Differential revision: https://reviews.llvm.org/D42388

Test plan: make check-all

llvm-svn: 323146

When CMAKE_SYSROOT or CMAKE_FIND_ROOT_PATH is set, cmake
recommends setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
globally which means find_path() always prepends CMAKE_SYSROOT or
CMAKE_FIND_ROOT_PATH to all paths used in the search.

However, these find_path() invocations are looking for paths in
the libcxx and libunwind projects on the host system, not the
target system, which can be done by passing
NO_CMAKE_FIND_ROOT_PATH.

Differential Revision: https://reviews.llvm.org/D41623

llvm-svn: 323145

For sections with different virtual and physical addresses, alignment and
placement in the output binary should be based on the physical address.

Ran into this problem with a bare metal ARM project where llvm-objcopy added a
lot of zero-padding before the .data section that had differing addresses. GNU
objcopy did not add the padding, and after this fix, neither does llvm-objcopy.

Update a test case so a section has different physical and virtual addresses.

Fixes B35708

Authored By: Owen Shaw (owenpshaw)

Differential Revision: https://reviews.llvm.org/D41619

llvm-svn: 323144

When CMAKE_SYSROOT or CMAKE_FIND_ROOT_PATH is set, cmake
recommends setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
globally which means find_path() always prepends CMAKE_SYSROOT or
CMAKE_FIND_ROOT_PATH to all paths used in the search.

However, this find_path() invocation is looking for a path in the
libcxxabi project on the host system, not the target system,
which can be done by passing NO_CMAKE_FIND_ROOT_PATH.

Differential Revision: https://reviews.llvm.org/D41622

llvm-svn: 323143