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Aggressive constprop in LinearAlgebra.wrap (#51582)
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This helps with type-stability, as the flag `tA` is usually known from
the type of the matrix.
On master,
```julia
julia> f(A) = LinearAlgebra.wrap(A, 'N')
f (generic function with 1 method)

julia> @code_typed f([1;;])
CodeInfo(
1 ─ %1 = invoke LinearAlgebra.wrap(A::Matrix{Int64}, 'N'::Char)::Union{Adjoint{Int64, Matrix{Int64}}, Hermitian{Int64, Matrix{Int64}}, Symmetric{Int64, Matrix{Int64}}, Transpose{Int64, Matrix{Int64}}, Matrix{Int64}}
└──      return %1
) => Union{Adjoint{Int64, Matrix{Int64}}, Hermitian{Int64, Matrix{Int64}}, Symmetric{Int64, Matrix{Int64}}, Transpose{Int64, Matrix{Int64}}, Matrix{Int64}}
```
This PR
```julia
julia> @code_typed f([1;;])
CodeInfo(
1 ─     return A
) => Matrix{Int64}
```

(cherry picked from commit 0fd7f72)
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jishnub authored and KristofferC committed Oct 9, 2023
1 parent 1e95bf8 commit 8c387e3
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Showing 2 changed files with 9 additions and 1 deletion.
2 changes: 1 addition & 1 deletion stdlib/LinearAlgebra/src/LinearAlgebra.jl
Original file line number Diff line number Diff line change
Expand Up @@ -465,7 +465,7 @@ wrapper_char(A::Hermitian) = A.uplo == 'U' ? 'H' : 'h'
wrapper_char(A::Hermitian{<:Real}) = A.uplo == 'U' ? 'S' : 's'
wrapper_char(A::Symmetric) = A.uplo == 'U' ? 'S' : 's'

function wrap(A::AbstractVecOrMat, tA::AbstractChar)
Base.@constprop :aggressive function wrap(A::AbstractVecOrMat, tA::AbstractChar)
if tA == 'N'
return A
elseif tA == 'T'
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8 changes: 8 additions & 0 deletions stdlib/LinearAlgebra/test/matmul.jl
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,14 @@ mul_wrappers = [
m -> adjoint(m),
m -> transpose(m)]

@testset "wrap" begin
f(A) = LinearAlgebra.wrap(A, 'N')
A = ones(1,1)
@test @inferred(f(A)) === A
g(A) = LinearAlgebra.wrap(A, 'T')
@test @inferred(g(A)) === transpose(A)
end

@testset "matrices with zero dimensions" begin
for (dimsA, dimsB, dimsC) in (
((0, 5), (5, 3), (0, 3)),
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