This is the first in a series of patches that will adds a new processor trace plug-in to LLDB.

The idea for this first patch to to add the plug-in interface with simple commands for the trace files that can "load" and "dump" the trace information. We can test the functionality and ensure people are happy with the way things are done and how things are organized before moving on to adding more functionality.

Processor trace information can be view in a few different ways:
- post mortem where a trace is saved off that can be viewed later in the debugger
- gathered while a process is running and allow the user to step back in time (with no variables, memory or registers) to see how each thread arrived at where it is currently stopped.

This patch attempts to start with the first solution of loading a trace file after the fact. The idea is that we will use a JSON file to load the trace information. JSON allows us to specify information about the trace like:
- plug-in name in LLDB
- path to trace file
- shared library load information so we can re-create a target and symbolicate the information in the trace
- any other info that the trace plug-in will need to be able to successfully parse the trace information
  - cpu type
  - version info
  - ???

A new "trace" command was added at the top level of the LLDB commmands:
- "trace load"
- "trace dump"

I did this because if we load trace information we don't need to have a process and we might end up creating a new target for the trace information that will become active. If anyone has any input on where this would be better suited, please let me know. Walter Erquinigo will end up filling in the Intel PT specific plug-in so that it works and is tested once we can agree that the direction of this patch is the correct one, so please feel free to chime in with ideas on comments!

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D85705

Updated file paths and function signatures in section
"Adding a new type".

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D88049

Extend the handling of memory intrinsics to also include non-
target-specific intrinsics, in particular masked loads and stores.

Invent "isHandledNonTargetIntrinsic" to distinguish between intrin-
sics that should be handled natively from intrinsics that can be
passed to TTI.

Add code that handles masked loads and stores and update the
testcase to reflect the results.

Differential Revision: https://reviews.llvm.org/D87340

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D87932

This patch adds a utility based on SuperVectorizer to vectorize an
affine loop nest using a given vectorization strategy. This strategy allows
targeting specific loops for vectorization instead of relying of the
SuperVectorizer analysis to choose the right loops to vectorize.

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D85869

SimplifyCFG's options should always be overridden by command line flags,
but they mistakenly weren't in the default constructor.

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D87718

Scheduling information is of little value when they may disrupt the
pipeline.  This patch allows omitting the scheduling information for CSR
instructions while still setting `SchedMachineModel::CompleteModel`.  For
specific cases, any scheduling information added will be used by the
scheduler.

Differential revision: https://reviews.llvm.org/D85366

A few fixes while trying to figure out why tests are being skipped for arsenm:

- We check `$compiler -v`, but `-v` is `--verbose`, not `--version`. Use the long flag name.
- We check all lines matching `version ...`, but we should exit early for the first version string we see (which should be the main one). I'm not sure if this is the issue, but perhaps this is causing some users to skip some tests if another "version ..." is showing up later.
- Having `\.` in a python string is triggering pylint warnings, because it should be escaped as a regex string, e.g. `r'\.' However, `.` in a character class does not need to be escaped, as it matches only a literal `.` in that context.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D88051

The vector-immediate cases are handled elsewhere in an earlier commit.

In order to select the immediate forms using the imported patterns, we need to
lower them into new G_VASHR/G_VLSHR target generic ops. Add a combine to do this
matching build_vector of constant operands.

With this, we get selection for free.

Sets the content for the section entry pages Hugo side.

Differential Revision: https://reviews.llvm.org/D87969

Selection support for these is coming up.

performing list-initialization of a char array reference from a braced
string literal of a smaller size.

Differential Revision: https://reviews.llvm.org/D88047

[ASTImporter] Modifying ImportDeclContext(...) to ensure that we also handle the case when the FieldDecl is an ArrayType whose ElementType is a RecordDecl

When we fixed ImportDeclContext(...) in D71378 to make sure we complete each
FieldDecl of a RecordDecl when we are importing the definition we missed the
case where a FeildDecl was an ArrayType whose ElementType is a record.

This fix was motivated by a codegen crash during LLDB expression parsing. Since
we were not importing the definition we were crashing during layout which
required all the records be defined.

Differential Revision: https://reviews.llvm.org/D86660

This reverts commit 4d85444b.

This commit broke building lldb's NativeProcessProtocolTest.cpp,
with errors like these:

In file included from include/llvm/Support/Process.h:32:0,
                 from tools/lldb/unittests/Host/NativeProcessProtocolTest.cpp:12:
include/llvm/Support/Program.h:39:11: error: reference to ‘pid_t’ is ambiguous
   typedef pid_t procid_t;

/usr/include/sched.h:38:17: note: candidates are: typedef __pid_t pid_t
 typedef __pid_t pid_t;

tools/lldb/include/lldb/lldb-types.h:85:18: note: typedef uint64_t lldb::pid_t
 typedef uint64_t pid_t;

1. Store intrinsic ID in ParseMemoryInst instead of a boolean flag
   "IsTargetMemInst". This will make it easier to add support for
   target-independent intrinsics.
2. Extract the complex multiline conditions from EarlyCSE::processNode
   into a new function "getMatchingValue".

Differential Revision: https://reviews.llvm.org/D87691

These patterns and type uses were added by mistake by commit
1372e23c

The patch modifies HexagonVectorLoopCarriedReuse pass to make it compatible with both Legacy Pass Manager through HexagonVectorLoopCarriedReuseLegacyPass and with New Pass Manager through HexagonVectorLoopCarriedReusePass.

Reviewed By: pzheng

Differential Revision: https://reviews.llvm.org/D86955

If we are going to write handler data (that is written as variable
length data following after the unwind info in .xdata), we need to
emit the handler data immediately, but for cases where no such
info is going to be written, skip emitting it right away. (Unwind
info for all remaining functions that hasn't gotten it emitted
directly is emitted at the end.)

This does slightly change the ordering of sections (triggering a
bunch of updates to DebugInfo/COFF tests), but the change should be
benign.

This also matches GCC's assembly output, which doesn't output
.seh_handlerdata unless it actually is needed.

For ARM64, the unwind info can be packed into the runtime function
entry itself (leaving no data in the .xdata section at all), but
that can only be done if there's no follow-on data in the .xdata
section. If emission of the unwind info is triggered via
EmitWinEHHandlerData (or the .seh_handlerdata directive), which
implicitly switches to the .xdata section, there's a chance of the
caller wanting to pass further data there, so the packed format
can't be used in that case.

Differential Revision: https://reviews.llvm.org/D87448

When cross compiling with clang-cl, clang splits the INCLUDE env
variable around semicolons (clang/lib/Driver/ToolChains/MSVC.cpp,
MSVCToolChain::AddClangSystemIncludeArgs) and lld splits the
LIB variable similarly (lld/COFF/Driver.cpp,
LinkerDriver::addLibSearchPaths). Therefore, the consensus for
cross compilation with clang-cl and lld-link seems to be to use
semicolons, despite path lists normally being separated by colons
on unix and EnvPathSeparator being set to that.

Therefore, handle the LIB variable similarly in Clang, when
handling lib file arguments when driving linking via Clang.

This fixes commands like "clang-cl test.c -Fetest.exe kernel32.lib" in
a cross compilation setting. Normally, most users call (lld-)link
directly, but meson happens to use this command syntax for
has_function() tests.

Differential Revision: https://reviews.llvm.org/D88002

GCC 8 changed behaviour wrt this, and made it consistent for cross
compilation cases. While it's a change, it's a more sensible behaviour
going forward.

Differential Revision: https://reviews.llvm.org/D88005

Added support for GNU named variadic macros in
macro expansion for plist generation.

Fix for https://bugs.llvm.org/show_bug.cgi?id=44493

Reviewed By: Szelethus

Differential Revision: https://reviews.llvm.org/D87942

We were already using this code pattern right after
the loop, so this makes it consistent.

We no longer treat the frame register like a function argument, so the
problem this avoided is no longer relevant.

This reverts commit dbd53a1f.

Needed lldb test updates

Differential Revision: https://reviews.llvm.org/D84988

This allows diagnosing missing substitution issues even when doing
availability feature detection in the DSL.

This pass is like DeadCodeEliminationPass, but only does one pass
through a function instead of iterating on users of eliminated
instructions.

DeadCodeEliminationPass should be used in all cases.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D87933

[ELF][test] Delete large temporary files and make some temporary files smaller with two text segments

Large files are cumbersome on some filesystems and can more easily trigger ENOSPC.

Some tests use two text sections with output section addresses to test branch ranges.
Use two text segments to prevent LLD from filling the gap and unnecessarily increasing the output size.

With this change, there is no test/ELF temporary file larger than 100MiB.

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D88037

This updates the C++ ABI argument classification code to use the logic
from D72114, fixing an ABI incompatibility with MSVC.

Part of PR44395.

Differential Revision: https://reviews.llvm.org/D87923

check-mlir target run tests simultaneously with multiple threads. This caused multiple threads to invoke the `lld::elf::link()` interface at the same time. Since the interface does not have a thread-safe implementation, add a metex to prevent multi-threaded access.

I discovered this by looking the the failure stack trace. lld/ELF/symbolTable.cpp, SymbolTable::insert() hit into an assert with related to Epoch Trackers. The root cause is to due to there is no protection around the symMap (update) which is implemented in non-thread safe data structure: denseMap.

Differential Revision: https://reviews.llvm.org/D88038

Mistakenly removed initialization of `Changed` in https://reviews.llvm.org/D87806.