If we vectorize a loop with multiple exits, all exiting branches should
be considered uniform, as the resulting loop will be controlled by the
canonical IV only. Previously we were overestimating the cost of values
contributing to the other exits.

This was suggested during the review of
https://github.com/llvm/llvm-project/pull/89413

This does not change the experimental state of modules.

Remove OpenMP FIR lowering tests. These are now replaced by HLFIR based
tests. This might hopefully speedup testing as well.

external decls

This patch fixes a FIXME in StoredDeclList::replaceExternalDecls.

StoredDeclList::replaceExternalDecls will iterate the list first to
remove some declarations and iterate the list again to get the tail of
the list.

It should be better to avoid the second iterations.

The previous patch implemented
- P2713R1 Escaping improvements in std::format
- LWG3965 Incorrect example in [format.string.escaped] p3 for formatting
of combining characters

These changes were correct, but had a size and performance penalty. This
patch improves the size and performance of the previous patch. The
performance is still worse than before since the lookups may require two
property lookups instead of one before implementing the paper. The
changes give a tighter coupling between the Unicode data and the
algorithm. Additional tests are added to notify about changes in future
Unicode updates.

Before
```
-----------------------------------------------------------------------
Benchmark                             Time             CPU   Iterations
-----------------------------------------------------------------------
BM_ascii_escaped<char>           110704 ns       110696 ns         6206
BM_unicode_escaped<char>         101371 ns       101374 ns         6862
BM_cyrillic_escaped<char>         63329 ns        63327 ns        11013
BM_japanese_escaped<char>         41223 ns        41225 ns        16938
BM_emoji_escaped<char>           111022 ns       111021 ns         6304
BM_ascii_escaped<wchar_t>        112441 ns       112443 ns         6231
BM_unicode_escaped<wchar_t>      102776 ns       102779 ns         6813
BM_cyrillic_escaped<wchar_t>      58977 ns        58975 ns        11868
BM_japanese_escaped<wchar_t>      36885 ns        36886 ns        18975
BM_emoji_escaped<wchar_t>        115885 ns       115881 ns         6051
```

The first change is to manually encode the entire last area and make a
manual exception for the 240 excluded entries. This reduced the table
from 1077 to 729 entries and gave the following benchmark results.
```
-----------------------------------------------------------------------
Benchmark                             Time             CPU   Iterations
-----------------------------------------------------------------------
BM_ascii_escaped<char>           104777 ns       104776 ns         6550
BM_unicode_escaped<char>          96980 ns        96982 ns         7238
BM_cyrillic_escaped<char>         60254 ns        60251 ns        11670
BM_japanese_escaped<char>         44452 ns        44452 ns        15734
BM_emoji_escaped<char>           104557 ns       104551 ns         6685
BM_ascii_escaped<wchar_t>        107456 ns       107454 ns         6505
BM_unicode_escaped<wchar_t>       96219 ns        96216 ns         7301
BM_cyrillic_escaped<wchar_t>      56921 ns        56904 ns        12288
BM_japanese_escaped<wchar_t>      39530 ns        39529 ns        17492
BM_emoji_escaped<wchar_t>        108494 ns       108496 ns         6408
```

An entry in the table can only contain 2048 code points. For larger
ranges there are multiple entries split in chunks with a maximum size of
2048 entries. To encode the entire Unicode code point range 21 bits are
required. The manual part starts at 0x323B0 this means all entries in
the table fit in 18 bits. This allows to allocate 3 additional bits for
the range. This allows entries to have 16384 elements. This range always
avoids splitting the range in multiple chunks.

This reduces the number of table elements from 729 to 711 and gives the
following benchmark results.
```
-----------------------------------------------------------------------
Benchmark                             Time             CPU   Iterations
-----------------------------------------------------------------------
BM_ascii_escaped<char>           104289 ns       104289 ns         6619
BM_unicode_escaped<char>          96682 ns        96681 ns         7215
BM_cyrillic_escaped<char>         59673 ns        59673 ns        11732
BM_japanese_escaped<char>         41983 ns        41982 ns        16646
BM_emoji_escaped<char>           104119 ns       104120 ns         6683
BM_ascii_escaped<wchar_t>        104503 ns       104505 ns         6693
BM_unicode_escaped<wchar_t>       93426 ns        93423 ns         7489
BM_cyrillic_escaped<wchar_t>      54858 ns        54859 ns        12742
BM_japanese_escaped<wchar_t>      36385 ns        36384 ns        19259
BM_emoji_escaped<wchar_t>        105608 ns       105610 ns         6592
```

Currently, the vsetvli pass tracks the define instruction through
`MRI->getVRegDef` due to the SSA form.

This patch keeps the AVLReg DefMI within VSETVLInfo during construction.
And replace `MRI->getVRegDef(AVLReg)` with `getAVLRegDefMI()`.

This information is useful when vsetvli pass live in post-ra situation.

The testcases don't change because the VReg always has a unique def in
SSA.

Close https://github.com/llvm/llvm-project/issues/88400

For the reproducer:

```
//--- header.h

namespace N {
    template<typename T>
    concept X = true;

    template<X T>
    class Y {
    public:
        template<X U>
        friend class Y;
    };

    inline Y<int> x;
}

//--- bar.cppm
module;
export module bar;
namespace N {
    // To make sure N::Y won't get elided.
    using N::x;
}

//--- foo.cc
// expected-no-diagnostics
import bar;
void y() {
    N::Y<int> y{};
};
```

it will crash. The root cause is that in
`StoredDeclsList::replaceExternalDecls`, we will replace the
existing declarations with external declarations.

Then for the reproducer, the redecl chain for Y is like:

```
Y (Local) -> Y (Local, friend) -> Y (Imported) -> Y(Imported, friend)
```

Before the lookup, the stored lookup result is `Y(Local)` then we find
`Y(Imported)`. And now we repalce `Y(Local)` with `Y(Imported)`. But
`Y(Imported)` is not visible. So we tried to find if there is any
redeclarations visible but we find `Y(Local, friend)`, then problem
happens.

The solution is try to avoid the replace to happen if the external
declaration has lower visibility then we can always find the local
declarations. This may help the lookup performance slightly.

Also I found the implementation of
`StoredDeclsList::replaceExternalDecls` is not efficiency. It has an
`O(n*m)` complexities. But let's improve that in the future.

In RISC-V ISel, the instruction `czero.eqz a0, a0, a0` is meaningless.
This patch does the following folds in ISel:
```
czero_eqz x, (setcc x, 0, ne) -> x
czero_nez x, (setcc x, 0, eq) -> x
```

---------

Signed-off-by: Zhijin Zeng <zhijin.zeng@spacemit.com>

This PR includes:
* vsadd.vv/vsaddu.vv
* vaadd.vv/vaaddu.vv
* vsmul.vv

So we can only mantain one place.

Reviewers: preames, yetingk, topperc

Reviewed By: topperc

Pull Request: https://github.com/llvm/llvm-project/pull/90187

This may simplify the usage of tools like `opt`, `llc`, etc.

Reviewers: michaelmaitland, 4vtomat, preames, asb

Reviewed By: michaelmaitland, preames, 4vtomat

Pull Request: https://github.com/llvm/llvm-project/pull/84877

We should remove the `experimental-` prefix when printing march
string.

We didn't meet this problem because there is no processor containing
experimental extensions.

Reviewers: fpetrogalli, asb, topperc

Reviewed By: topperc, asb

Pull Request: https://github.com/llvm/llvm-project/pull/90185

`llvm.trap` will be convert as unreachable which is terminator.
Instruction after terminator will cause validation failed.
This PR introduces a pass to clean instruction after terminator.
Fixes: https://github.com/llvm/llvm-project/issues/68770
Reapply: #90207

Set this in the cache file directly instead of via the test-release.sh
script so that the release builds can be reproduced with just the cache
file.

Add test coverage for cost-model code-paths not covered by current unit
tests in preparation for
 https://github.com/llvm/llvm-project/pull/67934.

Reverts llvm/llvm-project#90207

LLD Bots are broken.

Fix minor style problems in release notes.

C23 introduces the `nullptr` constant similar to C++11 which means that
the checker `modernize-use-nullptr` can be used on C23 code as well.

This PR enables the checker to be run on C23 and adds testcases.

See N3042:
https://open-std.org/JTC1/SC22/WG14/www/docs/n3042.htm

These did not have proper floating point uses so weren't representative
samples. The bitcast inserted by lowering could be absorbed by the
load/store on the source/use.

`llvm.trap` will be convert as `unreachable` which is terminator.
Instruction after terminator will cause validation failed.
This PR introduces a pass to clean instruction after terminator.
Fixes: #68770.

Fixes #90286

This patch automatically formats the code.

LLVM intrinsics `get_fpmode`, `set_fpmode` and `reset_fpmode` operate
control modes, the bits of FP environment that affect FP operations. On
AArch64 these bits are in FPCR. The lowering implemented to produce code
close to that of GLIBC.

This patch does:
- Preserve loop info when unfolding selects.
- Reduce the search space for loop paths.

- The behavior is similar to UCOMISD on x86, which is also used to
compare two fp values, specifically on handling of NaNs.
- Update related tests regarding this change.
- The further goal is to implement `llvm.minimum` and `llvm.maximum`
intrinsics for MIPS R6 and Pre-R6.

Part of https://github.com/llvm/llvm-project/issues/64207

For most algorithms we've just added underscores to the detail function.
This changes `std::find` to match that pattern.

This patch adds to StringRef the equivalent of
std::string_view::{starts,ends}_with(char) in C++20.

Reverts llvm/llvm-project#90307

Breaks bots https://lab.llvm.org/buildbot/#/builders/5/builds/42943

preliminary steps
poison symbols

There is the `MulSIExtendedRHSOne` canonicalization for
arith.mulsi_extended that is defined as follows: `mulsi_extended(x, 1)
-> [x, extsi(cmpi slt, x, 0)]`. In the implementation of this, there is
a `IsScalarOrSplatOne` constraint for the second argument. However, this
constraint does not correctly handle situation when multiplying i1
values. Therefore, an additional constraint has been added which checks
the second argument for strict positivity.

fix #88732

Primary motivation: is that after #84651 msan will
complain if fields accessed after ~__no_destroy.

My understanding of the https://eel.is/c++draft/basic.life#10
Static object with trivial destruction has program lifetime.
Static object with empty destuctor has implicit lifetime, and
accessing the object after lifetime is UB.

It was UB before #84651, it's just msan ignored union members.

Existing code with unions uses empty destructor, so accessing after
the main() can cause UB.

"placement new" version can have trivial destructor, so there is no end
of lifetime.

Secondary motivation: empty destructor will register __cxa_atexit with
-O0.
https://gcc.godbolt.org/z/hce587b65

We can not remove the destructor with union where
_Tp can have non-trivial destructor.

But we can remove destructor if we use in-place
new instead of union.
https://gcc.godbolt.org/z/Yqxx57eEd - empty even with -O0.

New test fails without the patch on

https://lab.llvm.org/buildbot/#/builders/sanitizer-x86_64-linux-bootstrap-msan

This patch refactors the llvm-mca rules slightly so that the source
files within the tool source directory but not the library source
directory are included in a separate cc_library. This patch also adds
the llvm-mca unittests.