…#51371)

~This is just me proposing a suggestion from @KristofferC in
https://discourse.julialang.org/t/debug-has-massive-performance-impact/103974/22,
it's all his code / idea, not mine.~

This PR makes it so that on windows, we pre-allocate an `IdDict` and
every time someone looks up environment variables (motivating example
here is `@debug` statements), we store the result of
`cwstring(::String)` in that `IdDict` so that it doesn't need to be
re-computed for future uses.

The idea behind this is that people have observed that [using `@debug`
is significantly more costly on Windows than other
platforms](https://discourse.julialang.org/t/debug-has-massive-performance-impact/103974),
even though we have documented in that manual that it should be a really
cheap operation. @KristofferC suggests this is due to the fact that
[checking environment variables in Windows is more
costly](https://discourse.julialang.org/t/debug-has-massive-performance-impact/103974/18).

~The idea here is that we preallocate a `Cwstring` on Windows that just
holds the text `"JULIA_DEBUG"`, so that if `access_env(f,
"JULIA_DEBUG")` gets called, we don't need to create a new `Cwstring`
and then throw it away each time.~

---------

Co-authored-by: Ian Butterworth <i.r.butterworth@gmail.com>
Co-authored-by: Jameson Nash <vtjnash@gmail.com>
(cherry picked from commit 9dcedaa)

Backported PRs:
- [x] #51213 <!-- Wait for other threads to finish compiling before
exiting -->
- [x] #51520 <!-- Make allocopt respect the GC verifier rules with non
usual address spaces -->
- [x] #51598 <!-- Use a simple error when reporting sysimg load
failures. -->
- [x] #51757 <!-- fix parallel peakflop usage -->
- [x] #51781 <!-- Don't make pkgimages global editable -->
- [x] #51848 <!-- allow finalizers to take any locks and yield during
exit -->
- [x] #51847 <!-- add missing wait during Timer and AsyncCondition close
-->
- [x] #50824 <!-- Add some aliasing warnings to docstrings for mutating
functions in Base -->
- [x] #51885 <!-- remove chmodding the pkgimages -->
- [x] #50207 <!-- [devdocs] Improve documentation about building
external forks of LLVM -->
- [x] #51967 <!-- further fix to the new promoting method for
AbstractDateTime subtraction -->
- [x] #51980 <!-- macroexpand: handle const/atomic struct fields
correctly -->
- [x] #51995 <!-- [Artifacts] Pass artifacts dictionary to
`ensure_artifact_installed` dispatch -->
- [x] #52098 <!-- Fix errors in `sort` docstring -->
- [x] #52136 <!-- Bump JuliaSyntax to 0.4.7 -->
- [x] #52140 <!-- Make c func `abspath` consistent on Windows. Fix
tracking path conversion. -->
- [x] #52009 <!-- fix completion that resulted in startpos of 0 for `\\
-->
- [x] #52192 <!-- cap the number of GC threads to number of cpu cores
-->
- [x] #52206 <!-- Make have_fma consistent between interpreter and
compiled -->
- [x] #52027 <!-- fix Unicode.julia_chartransform for Julia 1.10 -->
- [x] #52217 <!-- More helpful error message for empty `cpu_target` in
`Base.julia_cmd` -->
- [x] #51371 <!-- Memoize `cwstring` when used for env lookup /
modification on Windows -->
- [x] #52214 <!-- Turn Method Overwritten Error into a PrecompileError
-- turning off caching -->
- [x] #51895 <!-- Devdocs on fixing precompile hangs, take 2 -->
- [x] #51596 <!-- Reland "Don't mark nonlocal symbols as hidden"" -->
- [x] #51834 <!-- [REPLCompletions] allow symbol completions within
incomplete macrocall expression -->
- [x] #52010 <!-- Revert "Support sorting iterators (#46104)" -->
- [x] #51430 <!-- add support for async backtraces of Tasks on any
thread -->
- [x] #51471 <!-- Fix segfault if root task is NULL -->
- [x] #52194 <!-- Fix multiversioning issues caused by the parallel llvm
work -->
- [x] #51035 <!-- refactor GC scanning code to reflect jl_binding_t are
now first class -->
- [x] #52030 <!-- Bump Statistics -->
- [x] #52189 <!-- codegen: ensure i1 bool is widened to i8 before
storing -->
- [x] #52228 <!-- Widen diagonal var during `Type` unwrapping in
`instanceof_tfunc` -->
- [x] #52182 <!-- jitlayers: replace sharedbytes intern pool with one
that respects alignment -->

Contains multiple commits, manual intervention needed:
- [ ] #51092 <!-- inference: fix bad effects for recursion -->

Non-merged PRs with backport label:
- [ ] #52196 <!-- Fix creating custom log level macros -->
- [ ] #52170 <!-- fix invalidations related to `ismutable` -->
- [ ] #51479 <!-- prevent code loading from lookin in the versioned
environment when building Julia -->

…JuliaLang#51371)

~This is just me proposing a suggestion from @KristofferC in
https://discourse.julialang.org/t/debug-has-massive-performance-impact/103974/22,
it's all his code / idea, not mine.~

This PR makes it so that on windows, we pre-allocate an `IdDict` and
every time someone looks up environment variables (motivating example
here is `@debug` statements), we store the result of
`cwstring(::String)` in that `IdDict` so that it doesn't need to be
re-computed for future uses.

The idea behind this is that people have observed that [using `@debug`
is significantly more costly on Windows than other
platforms](https://discourse.julialang.org/t/debug-has-massive-performance-impact/103974),
even though we have documented in that manual that it should be a really
cheap operation. @KristofferC suggests this is due to the fact that
[checking environment variables in Windows is more
costly](https://discourse.julialang.org/t/debug-has-massive-performance-impact/103974/18).

~The idea here is that we preallocate a `Cwstring` on Windows that just
holds the text `"JULIA_DEBUG"`, so that if `access_env(f,
"JULIA_DEBUG")` gets called, we don't need to create a new `Cwstring`
and then throw it away each time.~

---------

Co-authored-by: Ian Butterworth <i.r.butterworth@gmail.com>
Co-authored-by: Jameson Nash <vtjnash@gmail.com>

…dows env variables (#52758)

Should fix #52711.

My analysis of the invalidation is as follows:

We added code to cache the conversion to `cwstring` in env handling on
Windows (#51371):

```julia
const env_dict = IdDict{String, Vector{UInt16}}()

function memoized_env_lookup(str::AbstractString)
    ...
    env_dict[str] = cwstring(str)
    ...
end

function access_env(onError::Function, str::AbstractString)
    var = memoized_env_lookup(str)
    ...
end
```

Since `IdDict` has `@nospecialize` on `setindex!` we compile this
method:

```julia
setindex!(::IdDict{String, Vector{UInt16}}, ::Any, ::Any)
```

which has an edge to:

```julia
convert(Type{Vector{Int64}}, Any})
```

But then StaticArrays comes along and adds a method

```julia
convert(::Type{Array{T, N}}, ::StaticArray)
```

which invalidates the `setindex!` (due to the edge to `convert`) which
invalidates the whole env handling on Windows which causes 4k other
methods downstream to be invalidated, in particular, the artifact string
macro which causes a significant delay in the next jll package you load
after loading StaticArrays.

There should be no performance penalty to this since strings already
does a hash for their `objectid`.

…dows env variables (#52758)

Should fix #52711.

My analysis of the invalidation is as follows:

We added code to cache the conversion to `cwstring` in env handling on
Windows (#51371):

```julia
const env_dict = IdDict{String, Vector{UInt16}}()

function memoized_env_lookup(str::AbstractString)
    ...
    env_dict[str] = cwstring(str)
    ...
end

function access_env(onError::Function, str::AbstractString)
    var = memoized_env_lookup(str)
    ...
end
```

Since `IdDict` has `@nospecialize` on `setindex!` we compile this
method:

```julia
setindex!(::IdDict{String, Vector{UInt16}}, ::Any, ::Any)
```

which has an edge to:

```julia
convert(Type{Vector{Int64}}, Any})
```

But then StaticArrays comes along and adds a method

```julia
convert(::Type{Array{T, N}}, ::StaticArray)
```

which invalidates the `setindex!` (due to the edge to `convert`) which
invalidates the whole env handling on Windows which causes 4k other
methods downstream to be invalidated, in particular, the artifact string
macro which causes a significant delay in the next jll package you load
after loading StaticArrays.

There should be no performance penalty to this since strings already
does a hash for their `objectid`.

(cherry picked from commit b7c24ed)

…dows env variables (JuliaLang#52758)

Should fix JuliaLang#52711.

My analysis of the invalidation is as follows:

We added code to cache the conversion to `cwstring` in env handling on
Windows (JuliaLang#51371):

```julia
const env_dict = IdDict{String, Vector{UInt16}}()

function memoized_env_lookup(str::AbstractString)
    ...
    env_dict[str] = cwstring(str)
    ...
end

function access_env(onError::Function, str::AbstractString)
    var = memoized_env_lookup(str)
    ...
end
```

Since `IdDict` has `@nospecialize` on `setindex!` we compile this
method:

```julia
setindex!(::IdDict{String, Vector{UInt16}}, ::Any, ::Any)
```

which has an edge to:

```julia
convert(Type{Vector{Int64}}, Any})
```

But then StaticArrays comes along and adds a method

```julia
convert(::Type{Array{T, N}}, ::StaticArray)
```

which invalidates the `setindex!` (due to the edge to `convert`) which
invalidates the whole env handling on Windows which causes 4k other
methods downstream to be invalidated, in particular, the artifact string
macro which causes a significant delay in the next jll package you load
after loading StaticArrays.

There should be no performance penalty to this since strings already
does a hash for their `objectid`.

(cherry picked from commit b7c24ed)