(cherry picked from commit346f38b)

The main motivation of this PR is tofix#55807.dc689fe tries to remove the slow`may_contain_union_decision` check by re-organizing the code path. Nowthe fast path has been removed and most of its optimization has beenintegrated into the preserved slow path.Since the slow path stores all inner ∃ decisions on the outer most Rstack, there might be overflow risk.aee69a4 should fix that concern.The reported MWE now becomes```julia  0.000002 seconds  0.000040 seconds (105 allocations: 4.828 KiB, 52.00% compilation time)  0.000023 seconds (105 allocations: 4.828 KiB, 49.36% compilation time)  0.000026 seconds (105 allocations: 4.828 KiB, 50.38% compilation time)  0.000027 seconds (105 allocations: 4.828 KiB, 54.95% compilation time)  0.000019 seconds (106 allocations: 4.922 KiB, 49.73% compilation time)  0.000024 seconds (105 allocations: 4.828 KiB, 52.24% compilation time)```Local bench also shows that72855cd slightly accelerates`OmniPackage.jl`'s loading```juliajulia>@time using OmniPackage# v1.11rc4 20.525278 seconds (25.36 M allocations: 1.606 GiB, 8.48% gc time, 12.89% compilation time: 77% of which was recompilation)# v1.11rc4+aee69a4+72855cd 19.527871 seconds (24.92 M allocations: 1.593 GiB, 8.88% gc time, 15.13% compilation time: 82% of which was recompilation)```(cherry picked from commitf3a36d7)

This PR is a potential fix for #54833.## DescriptionThe functionhttps://github.com/JuliaLang/julia/blob/2a06376c18afd7ec875335070743dcebcd85dee7/stdlib/LinearAlgebra/src/triangular.jl#L2220computes $\boldsymbol{A}^{\dfrac{1}{2^s}} - \boldsymbol{I}$ for areal-valued $2\times 2$ matrix $\boldsymbol{A}$ using Algorithm 5.1 in[R1]. However, the algorithm in [R1] as well as the above function donot handle the case $s=0.$ This fix extends the function to compute$\boldsymbol{A}^{\dfrac{1}{2^s}} - \boldsymbol{I} \Bigg|_{s=0} =\boldsymbol{A} - \boldsymbol{I}.$## Checklist- [X] Fix code: `stdlib\LinearAlgebra\src\triangular.jl` in function`_sqrt_pow_diag_block_2x2!(A, A0, s)`.- [X] Add test case: `stdlib\LinearAlgebra\test\triangular.jl`.- [X] Update `NEWS.md`.- [X] Testing and self review.|  Tag  | Reference || --- | --- || <nobr>[R1]</nobr> | Al-Mohy, Awad H. and Higham, Nicholas J. "ImprovedInverse Scaling and Squaring Algorithms for the Matrix Logarithm", 2011,url:https://eprints.maths.manchester.ac.uk/1687/1/paper11.pdf |---------Co-authored-by: Daniel Karrasch <daniel.karrasch@posteo.de>Co-authored-by: Oscar Smith <oscardssmith@gmail.com>(cherry picked from commit2cdfe06)

…#57138)(cherry picked from commit88c71dd)

…f4592 (#57225)Co-authored-by: IanButterworth <1694067+IanButterworth@users.noreply.github.com>

Ref:#57250.

…rror message (#57320)Backport of PR#56946 to v1.10.Co-authored-by: Shuhei Kadowaki<40514306+aviatesk@users.noreply.github.com>(cherry picked from commita3f336f)

Fixes#54560 (comment)(cherry picked from commit79e98e3)

Comparing objects by `==` will happily answer nonsense for malformedtype comparisons, such as `unwrap_unionall(A) == A`. Avoid forming thatquery. Additionally, need to recourse through Vararg when examining typestructure to make decisions.Fix#55076Fix#55189

(cherry picked from commit32ea18e)

This fixes up a couple of conspicuous problems I noticed when reviewingI'm unsure we should have accepted this pass in Base to begin with... Itshould at least be re-written to error on unexpected IR elements(instead of performing an invalid transform silently), but the realproblem is that this pass is out-of-pipeline and so it doesn't run onmost user code and we have much worse coverage compared to passes in themain Compiler.(cherry picked from commitc1db3a4)

…lignment to LLVM (#56938)Fixes#56937---------Co-authored-by: Oscar Smith <oscardssmith@gmail.com>(cherry picked from commit1e2758e)

…ead of the attempted written bytes. (#56980)(cherry picked from commit6ac351a)

(cherry picked from commit0a82b71)

PR#51317 was a bit over-eager about inferring inferring unreachablecode methods. Filter out the Vararg case, since that can be handled bysimply removing it instead of discarding the whole call.Fixes#56628(cherry picked from commiteb9f24c)

…e heap alignment to LLVM (#56938)"This reverts commit09704c7.