When clang is built against a prebuilt LLVM, LLVM_SOURCE_DIR is
empty, which due to a cmake quirk caused list lengths to get out
of sync. Add a workaround.

Summary:
Prior to landing D76961, preprocess via:
    $ llvm/utils/update_llc_test_checks.py \
      llvm/test/CodeGen/X86/callbr-asm-outputs.ll

Reviewers: void, MaskRay

Reviewed By: void, MaskRay

Subscribers: MaskRay, llvm-commits, srhines

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77356

After finding all such gadgets in a given function, the pass minimally inserts
LFENCE instructions in such a manner that the following property is satisfied:
for all SOURCE+SINK pairs, all paths in the CFG from SOURCE to SINK contain at
least one LFENCE instruction. The algorithm that implements this minimal
insertion is influenced by an academic paper that minimally inserts memory
fences for high-performance concurrent programs:

http://www.cs.ucr.edu/~lesani/companion/oopsla15/OOPSLA15.pdf

The algorithm implemented in this pass is as follows:

1. Build a condensed CFG (i.e., a GadgetGraph) consisting only of the following components:
  -SOURCE instructions (also includes function arguments)
  -SINK instructions
  -Basic block entry points
  -Basic block terminators
  -LFENCE instructions
2. Analyze the GadgetGraph to determine which SOURCE+SINK pairs (i.e., gadgets) are already mitigated by existing LFENCEs. If all gadgets have been mitigated, go to step 6.
3. Use a heuristic or plugin to approximate minimal LFENCE insertion.
4. Insert one LFENCE along each CFG edge that was cut in step 3.
5. Go to step 2.
6. If any LFENCEs were inserted, return true from runOnFunction() to tell LLVM that the function was modified.

By default, the heuristic used in Step 3 is a greedy heuristic that avoids
inserting LFENCEs into loops unless absolutely necessary. There is also a
CLI option to load a plugin that can provide even better optimization,
inserting fewer fences, while still mitigating all of the LVI gadgets.
The plugin can be found here: https://github.com/intel/lvi-llvm-optimization-plugin,
and a description of the pass's behavior with the plugin can be found here:
https://software.intel.com/security-software-guidance/insights/optimized-mitigation-approach-load-value-injection.

Differential Revision: https://reviews.llvm.org/D75937

See rational here: https://reviews.llvm.org/D76173#1922916
Time to compile Attr.h in isolation goes from 2.6s to 1.8s.

Original patch by Johannes, plus some additions from Reid to fix some
clang tooling targets.

Effect on transitive includes is marginal, though:

$ diff -u <(sort thedeps-before.txt) <(sort thedeps-after.txt) \
   | grep '^[-+] ' | sort | uniq -c | sort -nr
    104 -    /usr/local/google/home/rnk/llvm-project/clang/include/clang/AST/OpenMPClause.h
     87 -    /usr/local/google/home/rnk/llvm-project/llvm/include/llvm/Frontend/OpenMP/OMPContext.h
     19 -    /usr/local/google/home/rnk/llvm-project/llvm/include/llvm/ADT/SmallSet.h
     19 -    /usr/local/google/home/rnk/llvm-project/llvm/include/llvm/ADT/SetVector.h
     14 -    /usr/include/c++/9/set
...

Differential Revision: https://reviews.llvm.org/D76184

Summary:
Linalg makes it possible to interface codegen with externally precompiled HPC libraries. The mechanism to allow such interop uses a normalized ABI and the emission of C interface wrappers.

The mechanism controlling these C interface emission is too aggressive and makes it very easy to obtained undefined symbols for external function (e.g. the ones coming from libm).

This revision uses the newly introduced llvm.emit_c_interface function attribute which allows controlling this behavior at a function granularity. As a consequence LinalgToLLVM does not need to activate the C wrapper emission when adding the StdToLLVM patterns.

Differential Revision: https://reviews.llvm.org/D77364

Graceful lit shutdown on user keyboard interrupt [Ctrl+C] was a
longstanding goal of mine.  After a few refactorings this revision
finally enables it.  We use the following strategy to deal with
KeyboardInterrupt:
https://noswap.com/blog/python-multiprocessing-keyboardinterrupt

Printing of a helpful summary for interrupted runs (just as the one for
completed runs) will be tackled in future revisions.

Reviewed By: serge-sans-paille, rnk

Differential Revision: https://reviews.llvm.org/D77365

Adds a new data structure, ImmutableGraph, and uses RDF to find LVI gadgets and add them to a MachineGadgetGraph.

More specifically, a new X86 machine pass finds Load Value Injection (LVI) gadgets consisting of a load from memory (i.e., SOURCE), and any operation that may transmit the value loaded from memory over a covert channel, or use the value loaded from memory to determine a branch/call target (i.e., SINK).

Also adds a new target feature to X86: +lvi-load-hardening

The feature can be added via the clang CLI using -mlvi-hardening.

Differential Revision: https://reviews.llvm.org/D75936

It is an obvious part of D77326.

It removes some needless deep indentation and some redundant statements.
It prepares the code for a more clean next patch - DWARF index callbacks
in D77327.

Revert "[PowerPC] Replace subtract-from-zero float in version with fneg in PowerPC special fma compiler builtins"

The new test case causes bot failures.

This reverts commit ba87430c.

See discussion on https://reviews.llvm.org/D77184.

Differential Revision: https://reviews.llvm.org/D76949

Summary:
This patch includes two extensions:
1. It extends the GraphDiff to also keep the original list of updates
after legalization, not just the deletes/insert vectors.
It also provides an API to pop the first update (the updates are store
in reverse, such that the first update is at the end of the list)
2. It adds a bool to mark whether the given updates should be applied as
given, or applied in reverse. This moves the task of reversing the
updates (when the caller needs this) to a functionality inside
GraphDiff, versus having the caller do this.

The two changes could be split into two patches, but they seemed
reasonably small to be reviewed together.

Reviewers: kuhar, dblaikie

Subscribers: hiraditya, george.burgess.iv, mgrang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77167

Adding a pass that replaces every ret instruction with the sequence:

pop <scratch-reg>
lfence
jmp *<scratch-reg>

where <scratch-reg> is some available scratch register, according to the
calling convention of the function being mitigated.

Differential Revision: https://reviews.llvm.org/D75935

[PowerPC] Replace subtract-from-zero float in version with fneg in PowerPC special fma compiler builtins

This patch adds a test for the PowerPC fma compiler builtins, some variations
of which negate inputs and outputs. The code to generate IR for these
builtins was untested before this patch.

Originally, the code used the outdated method of subtracting floating point
values from -0.0 as floating point negation. This patch remedies that.

Patch by: Drew Wock <drew.wock@sas.com>
Differential Revision: https://reviews.llvm.org/D76949

Summary:
This patch fixes [[ https://bugs.llvm.org/show_bug.cgi?id=38025 | PR38025 ]]:
Wrong ABI used when building compiler-rt

Differential Revision: https://reviews.llvm.org/D74133

That option seems to be a remnant that has now been replaced by the
LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY setting.

Fixes PR45347.

Summary: Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=45363 | incorrect warning emitted by "modernize-use-default-member-init" (new to 10.0.0) ]].

Reviewers: aaron.ballman, alexfh, gribozavr2

Reviewed By: aaron.ballman

Subscribers: xazax.hun, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77199

PatternRewriter and derived classes provide a set of virtual methods to
manipulate blocks, which ConversionPatternRewriter overrides to keep track of
the manipulations and undo them in case the conversion fails. However, one can
currently create a block only by splitting another block into two. This not
only makes the API inconsistent (`splitBlock` is allowed in conversion
patterns, but `createBlock` is not), but it also make it impossible for one to
create blocks with argument lists different from those of already existing
blocks since in-place block updates are not supported either. Such
functionality precludes dialect conversion infrastructure from being used more
extensively on region-containing ops, for example, for value-returning "if"
operations. At the same time, ConversionPatternRewriter already allows one to
undo block creation as block creation is one of the primitive operations in
already supported region inlining.

Support block creation in conversion patterns by hooking `createBlock` on the
block action undo mechanism. This requires to make `Builder::createBlock`
virtual, similarly to Op insertion. This is a minimal change to the Builder
infrastructure that will later help support additional use cases such as block
signature changes. `createBlock` now additionally takes the types of the block
arguments that are added immediately so as to avoid in-place argument list
manipulation that would be illegal in conversion patterns.

Summary:
Remove usages of asserting vector getters in Type in preparation for the
VectorType refactor. The existence of these functions complicates the
refactor while adding little value.

Reviewers: kparzysz, sdesmalen, efriedma

Reviewed By: kparzysz

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77267

Previously, the tablegen() cmake command, which defines custom
commands for running tablegen, included several hardcoded paths.  This
becomes unwieldy as there are more users for which these paths are
insufficient.  For most targets, cmake uses include_directories() and
the INCLUDE_DIRECTORIES directory property to specify include paths.
This change picks up the INCLUDE_DIRECTORIES property and adds it
to the include path used when running tablegen.  As a side effect, this
allows us to remove several hard coded paths to tablegen that are redundant
with specified include_directories().

I haven't removed the hardcoded path to CMAKE_CURRENT_SOURCE_DIR, which
seems generically useful.  There are several users in clang which apparently
don't have the current directory as an include_directories().  This could
be considered separately.

The new version of this path uses list APPEND rather than list TRANSFORM,
in order to be compatible with cmake 3.4.3. If we u...

We can fix register class of PHI based on its all AGPR uses.
That leaves behind all PHIs which were already processed
earlier. Propagate RC back to PHI operands of a PHI.

Differential Revision: https://reviews.llvm.org/D77344

This was only kept until Chromium fixed their build of libc++, which
they have now done according to
	https://bugs.chromium.org/p/chromium/issues/detail?id=1067216

As detailed on PR45043, static analysis was warning that the StringRef::iterator Position argument was being ignored and the function was hardwired to use the Current iterator.

This patch ensures we use the provided iterator and removes the (barely necessary) setError wrapper that always used Current.

Differential Revision: https://reviews.llvm.org/D76512

Extracting to the same index that we are going to insert back into
allows forming select ("blend") shuffles and enables further transforms.

Admittedly, this is a quick-fix for a more general problem that I'm
hoping to solve by adding transforms for patterns that start with an
insertelement.

But this might resolve some regressions known to be caused by the
extract-extract transform (although I have not gotten more details on
those yet).

In the motivating case from PR34724:
https://bugs.llvm.org/show_bug.cgi?id=34724

The combination of subsequent instcombine and codegen transforms gets us this improvement:

  vmovshdup	%xmm0, %xmm2    ## xmm2 = xmm0[1,1,3,3]
  vhaddps	%xmm1, %xmm1, %xmm4
  vmovshdup	%xmm1, %xmm3    ## xmm3 = xmm1[1,1,3,3]
  vaddps	%xmm0, %xmm2, %xmm0
  vaddps	%xmm1, %xmm3, %xmm1
  vshufps	$200, %xmm4, %xmm0, %xmm0 ## xmm0 = xmm0[0,2],xmm4[0,3]
  vinsertps	$177, %xmm1, %xmm0, %xmm0 ## xmm0 = zero,xmm0[1,2],xmm1[2]

  -->

  vmovshdup	%xmm0, %xmm2    ## xmm2 = xmm0[1,1,3,3]
  vhaddps	%xmm1, %xmm1, %xmm1
  vaddps	%xmm0, %xmm2, %xmm0
  vshufps	$200, %xmm1, %xmm0, %xmm0 ## xmm0 = xmm0[0,2],xmm1[0,3]

Differential Revision: https://reviews.llvm.org/D76623

Added unit tests for 2 scenarios that were failing.
Made replace_path_prefix back to 3 parameters instead of 5, simplifying the implementation. The other 2 were always used with the default value.

This commit is intended to be the first of 3:
1) simplify/fix replace_path_prefix.
2) use it in the context of -fdebug-prefix-map and -fmacro-prefix-map (see D76869).
3) Make Windows version of replace_path_prefix insensitive to both case and separators (slash vs backslash).

Differential Revision: https://reviews.llvm.org/D77223

The testing script used to test libc++ historically did not like directories
without any testing files, so these tests had been added. Since this is
not necessary anymore, we can now remove these files. This has the benefit
that the total number of tests reflects the real number of tests more
closely, and we also skip some unnecessary work (especially relevant when
running tests over SSH).

However, some nothing_to_do.pass.cpp tests actually serve the purpose of
documenting that an area of the Standard doesn't need to be tested, or is
tested elsewhere. These files are not removed by this commit.

Removal done with:

  import os
  import itertools
  for (dirpath, dirnames, filenames) in itertools.chain(os.walk('./libcxx/test'),
                                                        os.walk('./libcxxabi/test')):
      if len(filenames + dirnames) > 1 and \
         any(p == 'nothing_to_do.pass.cpp' for p in filenames):
          os.remove(os.path.join(dirpath, 'nothing_to_do.pass.cpp'))

This reverts commit ae044c5b.

This breaks the buildbots, which use an older version of cmake.

Previously, the tablegen() cmake command, which defines custom
commands for running tablegen, included several hardcoded paths.  This
becomes unwieldy as there are more users for which these paths are
insufficient.  For most targets, cmake uses include_directories() and
the INCLUDE_DIRECTORIES directory property to specify include paths.
This change picks up the INCLUDE_DIRECTORIES property and adds it
to the include path used when running tablegen.  As a side effect, this
allows us to remove several hard coded paths to tablegen that are redundant
with specified include_directories().

I haven't removed the hardcoded path to CMAKE_CURRENT_SOURCE_DIR, which
seems generically useful.  There are several users in clang which apparently
don't have the current directory as an include_directories().  This could
be considered separately.

Differential Revision: https://reviews.llvm.org/D77156

Extend lowerShuffleWithPACK/matchShuffleWithPACK/createPackShuffleMask to handle compaction style shuffle masks that can be lowered to chains of PACKSS/PACKUS if their inputs are suitably sign/zero extended.

This helps avoid PSHUFB (and its mask load) for short shuffle chains, shuffle combining will still replace with a PSHUFB if we have enough shuffles as getFauxShuffleMask should recognise the PACKSS/PACKUS chains.

As discussed in post-commit review in https://reviews.llvm.org/D73501
if the goal of this is to help vectorizer, then we should actually
be teaching vectorizer to do this, because right now this rewrite
is still budget-limited, which isn't what we'd want.

Additionally, while the rest of the patch series was universally profitable,
this particular patch is reportedly (https://reviews.llvm.org/D73501#1905171)
exposing cost-modeling issues on ARM.

So let's just back this particular patch out. Once there's an undo transform,
this could be considered for reintegration.

This reverts commit 44edc6fd.