Fix for d3b26dea

(except on platforms that already opt in to specific versions - SCE,
Android, and Darwin using DWARFv4 explicitly, for instance)

Identified with modernize-use-default-member-init.

This is required by ychen. See https://reviews.llvm.org/D117542

[RISCV][NFC] Remove tailing whitespaces in RISCVInstrInfoVSDPatterns.td and RISCVInstrInfoVVLPatterns.td

This fixes bug 47716.

According to [module.interface]p2, it is meaningless to export an entity
which is not in namespace scope.
The reason why the compiler crashes is that the compiler missed
ExportDecl when the compiler traverse the subclass of DeclContext. So
here is the crash.

Also, the patch implements [module.interface]p6 in
Sema::CheckRedeclaration* functions.

Reviewed By: aaron.ballman, urnathan

Differential Revision: https://reviews.llvm.org/D112903

LLVM DebugInfo CodeGen synthesizes type declarations in type units when
referencing types that are not in type units. When those synthesized
types are templates and simplified template names (or mangled simplified
template names) are in use, the template arguments must be attached to
those declarations.

A deeper fix (with a CU or DICompositeType flag) that would also support
other uses of clang's -debug-forward-template-args (such as Sony's
platform) could/should be implemented to fix this more broadly.

Doing this causes a declaration of the internal linkage (anonymous
namespace) type to be emitted in the type unit, which would then be
ambiguous as to which internal linkage definition it refers to (since
the name is only valid internally).

It's possible these internal linkage types could be resolved relative to
the unit the TU is referred to from - but that doesn't seem ideal, and
there's no reason to put the type in a type unit since it can only be
defined in one CU anyway (since otherwise it'd be an ODR violation) & so
avoiding the type unit should be a smaller DWARF encoding anyway.

This also addresses an issue with Simplified Template Names where the
template parameter could not be rebuilt from the declaration emitted
into the TU (specifically for an enum non-type template parameter, where
looking up the enumerators is necessary to rebuild the full template
name)

Identified with readability-const-return-type.

Identified with bugprone-argument-comment.

We don't optimize this as well as we could. Bitreverse is always
expanded to bswap and a shift/and/or sequence to swap bits within a
byte. The newly created bswap will either becomes a shift/and/or
sequence or rev8 instruction. We don't always realize the bswap is
redundant with another bswap before or after the bitreverse.

Found while thinking about the brev8 instruction from the
Cryptography extension. It's equivalent to bswap(bitreverse(x)) or
bitreverse(bswap(x)).

Rename to include bitreverse. Add additional tests and Zbb command lines.

There's some overlapping tests with rv32zbb.ll and rv64zbb.ll. Maybe
I'll clean that up in a future patch.

This can always be lowered as PMULLW+PSRLWI+PACKUSWB

This patch adds a forward declaraiton of DynTypedNode.

DumpAST.h is relying on the forward declaration of DynTypedNode in
ASTContext.h, which is undesirable.

This patch moves the definition of ASTDiff later within the header
file.

Without this patch, the header depends on the forward decalrations of
SyntaxTree and ComparisonOptions from another header file, which is
not desirable.  Since SyntaxTree and ComparisonOptions are defined in
ASTDiff.h, we can move the definition of ASTDiff later and stop
relying on the forward declarations from another header file.

Allows us to reuse the ISD shift opcode instead of a mixture of ISD/X86ISD variants

The Zbk* extensions have some overlap with Zb so have been placed in this file.

Reviewed By: VincentWu

Differential Revision: https://reviews.llvm.org/D117958

This patch changes names of identifiers and their corresponding getters in
PresburgerSet to match those of IntegerPolyhedron.

Reviewed By: arjunp

Differential Revision: https://reviews.llvm.org/D117998

Identified with readability-redundant-control-flow.

Identified with readability-redundant-member-init.

Identified with llvm-header-guard.

* Merge parallel_for_each into parallelForEach (this removes 1 `Fn(...)` call)
* Change parallelForEach to use parallelForEachN
* Move parallelForEachN into Parallel.cpp

My x86-64 `lld` executable is 100KiB smaller.
No noticeable difference in performance.

Reviewed By: lattner

Differential Revision: https://reviews.llvm.org/D117510

<meme>How many layers of irony are you on?</meme>

Differential Revision: https://reviews.llvm.org/D117967

D108992 added self-multiply handling to KnownBits::mul but we don't use it yet..

Instead of having a test for i32 XLen and i64 XLen, use sed to
replace iXLen with i32/i64 before running llc.

This change covers all of the floating point tests.

Fixes parity codegen issue where we know all but the lowest bit is zero, we can replace the ICMPNE with 0 comparison with a ext/trunc

Differential Revision: https://reviews.llvm.org/D117983

Revert rG7c66aadd "[DAG] Fold (X & Y) != 0 --> zextOrTrunc(X & Y) iff everything but LSB is known zero (PR51312)"

Noticed a typo in the getBooleanContents call just after I pressed commit :(

Looks for duplicate includes and removes them.

Every time an include directive is processed, check a vector of filenames
to see if the included file has already been included.  If so, it issues
a warning and a replacement to remove the entire line containing the
duplicated include directive.

When a macro is defined or undefined, the vector of filenames is cleared.
This enables including the same file multiple times, but getting
different expansions based on the set of active macros at the time of
inclusion.  For example:

  #undef NDEBUG
  #include "assertion.h"
  // ...code with assertions enabled

  #define NDEBUG
  #include "assertion.h"
  // ...code with assertions disabled

Since macros are redefined between the inclusion of assertion.h,
they are not flagged as redundant.

Differential Revision: https://reviews.llvm.org/D7982

The behavior in Analysis (knownbits) implements poison semantics already,
and we expect the transforms (for example, in instcombine) derived from
those semantics, so this patch changes the LangRef and remaining code to
be consistent. This is one more step in removing "undef" from LLVM.

Without this, I think https://github.com/llvm/llvm-project/issues/53330
has a legitimate complaint because that report wants to allow subsequent
code to mask off bits, and that is allowed with undef values. The clang
builtins are not actually documented anywhere AFAICT, but we might want
to add that to remove more uncertainty.

Differential Revision: https://reviews.llvm.org/D117912

Fixes parity codegen issue where we know all but the lowest bit is zero, we can replace the ICMPNE with 0 comparison with a ext/trunc

Differential Revision: https://reviews.llvm.org/D117983

The register R1 is defined to have the constant value 0 in the avr-gcc
calling convention (which we follow). Unfortunately, we don't really
make use of it. This patch replaces `LDI 0` instructions with a copy
from R1.

This reduces code size: my AVR build of compiler-rt goes from 50660 to
50240 bytes of code size, which is a 0.8% reduction. Presumably it will
also improve execution speed, although I didn't measure this.

Differential Revision: https://reviews.llvm.org/D117425

Background: https://github.com/avr-rust/rust-legacy-fork/issues/126

In short, this workaround was introduced to fix a "ran out of registers
during regalloc" issue. The root cause has since been fixed in
https://reviews.llvm.org/D54218 so this workaround can be removed.

There is one test that changes a little bit, removing a single
instruction. I also compiled compiler-rt before and after this patch but
didn't see a difference. So presumably the impact is very low. Still,
it's nice to be able to remove such a workaround.

Differential Revision: https://reviews.llvm.org/D117831

Currently the fix hint is hardcoded to gsl::at(). This poses
a problem for people who, for a number of reasons, don't want
or cannot use the GSL library (introducing a new third-party
dependency into a project is not a minor task).

In these situations, the fix hint does more harm than good
as it creates confusion as to what the fix should be. People
can even misinterpret the fix "gsl::at" as e.g. "std::array::at",
which can lead to even more trouble (e.g. when having guidelines
that disallow exceptions).

Furthermore, this is not a requirement from the C++ Core Guidelines.
simply that array indexing needs to be safe. Each project should
be able to decide upon a strategy for safe indexing.

The fix-it is kept for people who want to use the GSL library.

Differential Revision: https://reviews.llvm.org/D117857