Changes

[llvm-objcopy][MachO] Implement --update-section

Implements `--update-section` which is currently supported for ELF for Mach-O as well

Reviewed By: alexander-shaposhnikov

Differential Revision: https://reviews.llvm.org/D117281

[X86] Regenerate avx512-mask-op.ll

Noticed on D86578 - several of the test cases were missing checks as they didn't start on a newline so the update script couldn't see them

[llvm-objdump] Use cast<> instead of dyn_cast<> to avoid dereference of nullptr

The pointers are always dereferenced immediately, so assert the cast is correct instead of returning nullptr

[CodeGenPrepare] Use dyn_cast result to check for null pointers

Simplifies logic and helps the static analyzer correctly check for nullptr dereferences

[llvm-objdump] Use cast<> instead of dyn_cast<> to avoid dereference of nullptr

The pointer is dereferenced immediately, so assert the cast is correct instead of returning nullptr

[clang-tidy] Use cast<>/castAs<> instead of dyn_cast<>/getAs<> to avoid dereference of nullptr

The pointer is dereferenced immediately, so assert the cast is correct instead of returning nullptr

[clangd] Use castAs<> instead of getAs<> to avoid dereference of nullptr

The pointer is dereferenced immediately, so assert the cast is correct instead of returning nullptr

[lldb] CxxModuleHandler - use cast<> instead of dyn_cast<> to avoid dereference of nullptr

The pointer is dereferenced immediately, so assert the cast is correct instead of returning nullptr

[lldb] PdbAstBuilder - use cast<> instead of dyn_cast<> to avoid dereference of nullptr

The pointers are dereferenced immediately, so assert the cast is correct instead of returning nullptr

[lldb] TerminalState::Save - fix unused variable warning

Non-POSIX target builds don't use the file descriptor

Fix "not all control paths return a value" warning. NFC.

[libc++] Mark LWG3541 as "Complete". NFC.

Differential Revision: https://reviews.llvm.org/D117956

[libc++] Fix LWG3437 "__cpp_lib_polymorphic_allocator is in the wrong header"

https://cplusplus.github.io/LWG/issue3437

Differential Revision: https://reviews.llvm.org/D117963

[X86] Add vector signbit parity checks for non-popcnt targets

Noticed while looking at D117983 - we miss some parity patterns with/without popcnt

[clang-tidy] Remove gsl::at suggestion from cppcoreguidelines-pro-bounds-constant-array-index

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

[AVR] Remove regalloc workaround for LDDWRdPtrQ

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

[AVR] Make use of the constant value 0 in R1

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

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

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

[IR] document and update ctlz/cttz intrinsics to optionally return poison rather than undef

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

[clang-tidy] Add readability-duplicate-include check

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

Revert rG7c66aaddb128dc0f342830c1efaeb7a278bfc48c "[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 :(

[gn build] Port d2e8fb331835

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

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

[RISCV] Merge some rvv intrinsic test cases that only differ by XLen type.

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.

[InstCombine] Add test coverage for PR48683

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

[libcxx][test] Make MSVC `<charconv>` test compile when testing MSVC

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

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

[Support] Simplify parallelForEach{,N}

* 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