From df43e8f1e7983f794ded10f991af819cda467a98 Mon Sep 17 00:00:00 2001
From: Alfredo Braunstein <alfredo.braunstein@polito.it>
Date: Thu, 10 Jan 2019 08:19:56 +0100
Subject: [PATCH 1/3] * Make length(A.nzval)==nnz(A) and add strict buffer
 checking #30662. * Add sizehint!(::SparseMatrixCSC, args...), * Fix illegal
 SparseMatrixCSC construction in cholmod and linalg. * Remove tests targetting
 now illegal buffers * Fix invalid buffer creation in kron and more

---
 NEWS.md                                   |   1 +
 stdlib/SparseArrays/src/higherorderfns.jl |  62 +++++------
 stdlib/SparseArrays/src/linalg.jl         |  49 ++++-----
 stdlib/SparseArrays/src/sparsematrix.jl   | 104 ++++++++++--------
 stdlib/SparseArrays/src/sparsevector.jl   |  16 ++-
 stdlib/SparseArrays/test/sparse.jl        |  41 +------
 stdlib/SparseArrays/test/sparsevector.jl  |   4 +-
 stdlib/SuiteSparse/src/cholmod.jl         | 125 ++++++++++++++--------
 stdlib/SuiteSparse/test/cholmod.jl        |  13 +--
 9 files changed, 212 insertions(+), 203 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 24be1feb2108d..8b327e90659b4 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -111,6 +111,7 @@ Standard library changes
 
 #### SparseArrays
 
+* new `sizehint!(::SparseMatrixCSC, ::Integer)` method ([#30676]).
 
 #### Dates
 
diff --git a/stdlib/SparseArrays/src/higherorderfns.jl b/stdlib/SparseArrays/src/higherorderfns.jl
index 383211267ee3b..089aeae326427 100644
--- a/stdlib/SparseArrays/src/higherorderfns.jl
+++ b/stdlib/SparseArrays/src/higherorderfns.jl
@@ -8,7 +8,7 @@ import Base: map, map!, broadcast, copy, copyto!, _extrema_dims, _extrema_itr
 
 using Base: front, tail, to_shape
 using ..SparseArrays: SparseVector, SparseMatrixCSC, AbstractSparseVector, AbstractSparseMatrixCSC,
-                      AbstractSparseMatrix, AbstractSparseArray, indtype, nnz, nzrange,
+                      AbstractSparseMatrix, AbstractSparseArray, indtype, nnz, nzrange, spzeros,
                       SparseVectorUnion, AdjOrTransSparseVectorUnion, nonzeroinds, nonzeros, rowvals, getcolptr, widelength
 using Base.Broadcast: BroadcastStyle, Broadcasted, flatten
 using LinearAlgebra
@@ -132,12 +132,17 @@ function trimstorage!(A::SparseVecOrMat, maxstored)
     resize!(storedvals(A), maxstored)
     return maxstored
 end
+
 function expandstorage!(A::SparseVecOrMat, maxstored)
-    length(storedinds(A)) < maxstored && resize!(storedinds(A), maxstored)
-    length(storedvals(A)) < maxstored && resize!(storedvals(A), maxstored)
+    if length(storedinds(A)) < maxstored
+        resize!(storedinds(A), maxstored)
+        resize!(storedvals(A), maxstored)
+    end
     return maxstored
 end
 
+_checkbuffers(S::SparseMatrixCSC) = (@assert length(getcolptr(S)) == size(S, 2) + 1 && getcolptr(S)[end] - 1 == length(rowvals(S)) == length(nonzeros(S)); S)
+_checkbuffers(S::SparseVector) = (@assert length(storedvals(S)) == length(storedinds(S)); S)
 
 # (2) map[!] entry points
 map(f::Tf, A::SparseVector) where {Tf} = _noshapecheck_map(f, A)
@@ -181,7 +186,7 @@ copy(bc::SpBroadcasted1) = _noshapecheck_map(bc.f, bc.args[1])
         storedvals(C)[1] = fofnoargs
         broadcast!(f, view(storedvals(C), 2:length(storedvals(C))))
     end
-    return C
+    return _checkbuffers(C)
 end
 
 function _diffshape_broadcast(f::Tf, A::SparseVecOrMat, Bs::Vararg{SparseVecOrMat,N}) where {Tf,N}
@@ -224,22 +229,13 @@ _maxnnzfrom(shape::NTuple{2}, A::AbstractSparseMatrixCSC) = nnz(A) * div(shape[1
 @inline _unchecked_maxnnzbcres(shape, As...) = _unchecked_maxnnzbcres(shape, As)
 @inline _checked_maxnnzbcres(shape::NTuple{1}, As...) = shape[1] != 0 ? _unchecked_maxnnzbcres(shape, As) : 0
 @inline _checked_maxnnzbcres(shape::NTuple{2}, As...) = shape[1] != 0 && shape[2] != 0 ? _unchecked_maxnnzbcres(shape, As) : 0
-@inline function _allocres(shape::NTuple{1}, indextype, entrytype, maxnnz)
-    storedinds = Vector{indextype}(undef, maxnnz)
-    storedvals = Vector{entrytype}(undef, maxnnz)
-    return SparseVector(shape..., storedinds, storedvals)
-end
-@inline function _allocres(shape::NTuple{2}, indextype, entrytype, maxnnz)
-    pointers = ones(indextype, shape[2] + 1)
-    storedinds = Vector{indextype}(undef, maxnnz)
-    storedvals = Vector{entrytype}(undef, maxnnz)
-    return SparseMatrixCSC(shape..., pointers, storedinds, storedvals)
-end
+@inline _allocres(shape::NTuple{1}, indextype, entrytype, maxnnz) = sizehint!(SparseVector(shape[1], indextype[], entrytype[]), maxnnz)
+@inline _allocres(shape::NTuple{2}, indextype, entrytype, maxnnz) = sizehint!(SparseMatrixCSC(shape..., fill(indextype(1), shape[2]+1), indextype[], entrytype[]), maxnnz)
 
 # (4) _map_zeropres!/_map_notzeropres! specialized for a single sparse vector/matrix
 "Stores only the nonzero entries of `map(f, Array(A))` in `C`."
 function _map_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat) where Tf
-    spaceC::Int = min(length(storedinds(C)), length(storedvals(C)))
+    spaceC::Int = length(nonzeros(C))
     Ck = 1
     @inbounds for j in columns(C)
         setcolptr!(C, j, Ck)
@@ -255,7 +251,7 @@ function _map_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat) where Tf
     end
     @inbounds setcolptr!(C, numcols(C) + 1, Ck)
     trimstorage!(C, Ck - 1)
-    return C
+    return _checkbuffers(C)
 end
 """
 Densifies `C`, storing `fillvalue` in place of each unstored entry in `A` and
@@ -274,7 +270,7 @@ function _map_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, A::SparseVecOrMa
     end
     # NOTE: Combining the fill! above into the loop above to avoid multiple sweeps over /
     # nonsequential access of storedvals(C) does not appear to improve performance.
-    return C
+    return _checkbuffers(C)
 end
 # helper functions for these methods and some of those below
 @inline _densecoloffsets(A::SparseVector) = 0
@@ -297,7 +293,7 @@ end
 
 # (5) _map_zeropres!/_map_notzeropres! specialized for a pair of sparse vectors/matrices
 function _map_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat, B::SparseVecOrMat) where Tf
-    spaceC::Int = min(length(storedinds(C)), length(storedvals(C)))
+    spaceC::Int = length(nonzeros(C))
     rowsentinelA = convert(indtype(A), numrows(C) + 1)
     rowsentinelB = convert(indtype(B), numrows(C) + 1)
     Ck = 1
@@ -336,7 +332,7 @@ function _map_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat, B::SparseVe
     end
     @inbounds setcolptr!(C, numcols(C) + 1, Ck)
     trimstorage!(C, Ck - 1)
-    return C
+    return _checkbuffers(C)
 end
 function _map_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, A::SparseVecOrMat, B::SparseVecOrMat) where Tf
     # Build dense matrix structure in C, expanding storage if necessary
@@ -368,13 +364,13 @@ function _map_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, A::SparseVecOrMa
             Cx != fillvalue && (storedvals(C)[jo + Ci] = Cx)
         end
     end
-    return C
+    return _checkbuffers(C)
 end
 
 
 # (6) _map_zeropres!/_map_notzeropres! for more than two sparse matrices / vectors
 function _map_zeropres!(f::Tf, C::SparseVecOrMat, As::Vararg{SparseVecOrMat,N}) where {Tf,N}
-    spaceC::Int = min(length(storedinds(C)), length(storedvals(C)))
+    spaceC::Int = length(nonzeros(C))
     rowsentinel = numrows(C) + 1
     Ck = 1
     stopks = _colstartind_all(1, As)
@@ -398,7 +394,7 @@ function _map_zeropres!(f::Tf, C::SparseVecOrMat, As::Vararg{SparseVecOrMat,N})
     end
     @inbounds setcolptr!(C, numcols(C) + 1, Ck)
     trimstorage!(C, Ck - 1)
-    return C
+    return _checkbuffers(C)
 end
 function _map_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, As::Vararg{SparseVecOrMat,N}) where {Tf,N}
     # Build dense matrix structure in C, expanding storage if necessary
@@ -421,7 +417,7 @@ function _map_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, As::Vararg{Spars
             activerow = min(rows...)
         end
     end
-    return C
+    return _checkbuffers(C)
 end
 
 # helper methods for map/map! methods just above
@@ -462,7 +458,7 @@ end
 # (7) _broadcast_zeropres!/_broadcast_notzeropres! specialized for a single (input) sparse vector/matrix
 function _broadcast_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat) where Tf
     isempty(C) && return _finishempty!(C)
-    spaceC::Int = min(length(storedinds(C)), length(storedvals(C)))
+    spaceC::Int = length(nonzeros(C))
     # C and A cannot have the same shape, as we directed that case to map in broadcast's
     # entry point; here we need efficiently handle only heterogeneous C-A combinations where
     # one or both of C and A has at least one singleton dimension.
@@ -509,7 +505,7 @@ function _broadcast_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat) where
     end
     @inbounds setcolptr!(C, numcols(C) + 1, Ck)
     trimstorage!(C, Ck - 1)
-    return C
+    return _checkbuffers(C)
 end
 function _broadcast_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, A::SparseVecOrMat) where Tf
     # For information on this code, see comments in similar code in _broadcast_zeropres! above
@@ -540,14 +536,14 @@ function _broadcast_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, A::SparseV
             end
         end
     end
-    return C
+    return _checkbuffers(C)
 end
 
 
 # (8) _broadcast_zeropres!/_broadcast_notzeropres! specialized for a pair of (input) sparse vectors/matrices
 function _broadcast_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat, B::SparseVecOrMat) where Tf
     isempty(C) && return _finishempty!(C)
-    spaceC::Int = min(length(storedinds(C)), length(storedvals(C)))
+    spaceC::Int = length(nonzeros(C))
     rowsentinelA = convert(indtype(A), numrows(C) + 1)
     rowsentinelB = convert(indtype(B), numrows(C) + 1)
     # C, A, and B cannot all have the same shape, as we directed that case to map in broadcast's
@@ -711,7 +707,7 @@ function _broadcast_zeropres!(f::Tf, C::SparseVecOrMat, A::SparseVecOrMat, B::Sp
     end
     @inbounds setcolptr!(C, numcols(C) + 1, Ck)
     trimstorage!(C, Ck - 1)
-    return C
+    return _checkbuffers(C)
 end
 function _broadcast_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, A::SparseVecOrMat, B::SparseVecOrMat) where Tf
     # For information on this code, see comments in similar code in _broadcast_zeropres! above
@@ -810,7 +806,7 @@ function _broadcast_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, A::SparseV
             end
         end
     end
-    return C
+    return _checkbuffers(C)
 end
 _finishempty!(C::SparseVector) = C
 _finishempty!(C::AbstractSparseMatrixCSC) = (fill!(getcolptr(C), 1); C)
@@ -861,7 +857,7 @@ end
 # (9) _broadcast_zeropres!/_broadcast_notzeropres! for more than two (input) sparse vectors/matrices
 function _broadcast_zeropres!(f::Tf, C::SparseVecOrMat, As::Vararg{SparseVecOrMat,N}) where {Tf,N}
     isempty(C) && return _finishempty!(C)
-    spaceC::Int = min(length(storedinds(C)), length(storedvals(C)))
+    spaceC::Int = length(nonzeros(C))
     expandsverts = _expandsvert_all(C, As)
     expandshorzs = _expandshorz_all(C, As)
     rowsentinel = numrows(C) + 1
@@ -909,7 +905,7 @@ function _broadcast_zeropres!(f::Tf, C::SparseVecOrMat, As::Vararg{SparseVecOrMa
     end
     @inbounds setcolptr!(C, numcols(C) + 1, Ck)
     trimstorage!(C, Ck - 1)
-    return C
+    return _checkbuffers(C)
 end
 function _broadcast_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, As::Vararg{SparseVecOrMat,N}) where {Tf,N}
     isempty(C) && return _finishempty!(C)
@@ -950,7 +946,7 @@ function _broadcast_notzeropres!(f::Tf, fillvalue, C::SparseVecOrMat, As::Vararg
             end
         end
     end
-    return C
+    return _checkbuffers(C)
 end
 
 # helper method for broadcast/broadcast! methods just above
diff --git a/stdlib/SparseArrays/src/linalg.jl b/stdlib/SparseArrays/src/linalg.jl
index 0ac2806b77a04..73fc0c7dee03a 100644
--- a/stdlib/SparseArrays/src/linalg.jl
+++ b/stdlib/SparseArrays/src/linalg.jl
@@ -935,16 +935,15 @@ function triu(S::AbstractSparseMatrixCSC{Tv,Ti}, k::Integer=0) where {Tv,Ti}
     end
     rowval = Vector{Ti}(undef, nnz)
     nzval = Vector{Tv}(undef, nnz)
-    A = SparseMatrixCSC(m, n, colptr, rowval, nzval)
     for col = max(k+1,1) : n
         c1 = getcolptr(S)[col]
-        for c2 in nzrange(A, col)
-            rowvals(A)[c2] = rowvals(S)[c1]
-            nonzeros(A)[c2] = nonzeros(S)[c1]
+        for c2 in colptr[col]:colptr[col+1]-1
+            rowval[c2] = rowvals(S)[c1]
+            nzval[c2] = nonzeros(S)[c1]
             c1 += 1
         end
     end
-    A
+    SparseMatrixCSC(m, n, colptr, rowval, nzval)
 end
 
 function tril(S::AbstractSparseMatrixCSC{Tv,Ti}, k::Integer=0) where {Tv,Ti}
@@ -965,17 +964,16 @@ function tril(S::AbstractSparseMatrixCSC{Tv,Ti}, k::Integer=0) where {Tv,Ti}
     end
     rowval = Vector{Ti}(undef, nnz)
     nzval = Vector{Tv}(undef, nnz)
-    A = SparseMatrixCSC(m, n, colptr, rowval, nzval)
     for col = 1 : min(n, m+k)
         c1 = getcolptr(S)[col+1]-1
-        l2 = getcolptr(A)[col+1]-1
-        for c2 = 0 : l2 - getcolptr(A)[col]
-            rowvals(A)[l2 - c2] = rowvals(S)[c1]
-            nonzeros(A)[l2 - c2] = nonzeros(S)[c1]
+        l2 = colptr[col+1]-1
+        for c2 = 0 : l2 - colptr[col]
+            rowval[l2 - c2] = rowvals(S)[c1]
+            nzval[l2 - c2] = nonzeros(S)[c1]
             c1 -= 1
         end
     end
-    A
+    SparseMatrixCSC(m, n, colptr, rowval, nzval)
 end
 
 ## diff
@@ -1340,7 +1338,6 @@ end
 
 ## kron
 @inline function kron!(C::SparseMatrixCSC, A::AbstractSparseMatrixCSC, B::AbstractSparseMatrixCSC)
-    nnzC = nnz(A)*nnz(B)
     mA, nA = size(A); mB, nB = size(B)
     mC, nC = mA*mB, nA*nB
 
@@ -1348,11 +1345,9 @@ end
     nzvalC = nonzeros(C)
     colptrC = getcolptr(C)
 
-    @boundscheck begin
-        length(colptrC) == nC+1 || throw(DimensionMismatch("expect C to be preallocated with $(nC+1) colptrs "))
-        length(rowvalC) == nnzC || throw(DimensionMismatch("expect C to be preallocated with $(nnzC) rowvals"))
-        length(nzvalC) == nnzC || throw(DimensionMismatch("expect C to be preallocated with $(nnzC) nzvals"))
-    end
+    nnzC = nnz(A)*nnz(B)
+    resize!(nzvalC, nnzC)
+    resize!(rowvalC, nnzC)
 
     col = 1
     @inbounds for j = 1:nA
@@ -1381,16 +1376,13 @@ end
 end
 
 @inline function kron!(z::SparseVector, x::SparseVector, y::SparseVector)
-    nnzx = nnz(x); nnzy = nnz(y); nnzz = nnz(z);
+    nnzx = nnz(x); nnzy = nnz(y);
     nzind = nonzeroinds(z)
     nzval = nonzeros(z)
 
-    @boundscheck begin
-        nnzval = length(nzval); nnzind = length(nzind)
-        nnzz = nnzx*nnzy
-        nnzval == nnzz || throw(DimensionMismatch("expect z to be preallocated with $nnzz nonzeros"))
-        nnzind == nnzz || throw(DimensionMismatch("expect z to be preallocated with $nnzz nonzeros"))
-    end
+    nnzz = nnzx*nnzy
+    resize!(nzind, nnzz)
+    resize!(nzval, nnzz)
 
     @inbounds for i = 1:nnzx, j = 1:nnzy
         this_ind = (i-1)*nnzy+j
@@ -1402,17 +1394,12 @@ end
 
 # sparse matrix ⊗ sparse matrix
 function kron(A::AbstractSparseMatrixCSC{T1,S1}, B::AbstractSparseMatrixCSC{T2,S2}) where {T1,S1,T2,S2}
-    nnzC = nnz(A)*nnz(B)
     mA, nA = size(A); mB, nB = size(B)
     mC, nC = mA*mB, nA*nB
     Tv = typeof(one(T1)*one(T2))
     Ti = promote_type(S1,S2)
-    colptrC = Vector{Ti}(undef, nC+1)
-    rowvalC = Vector{Ti}(undef, nnzC)
-    nzvalC  = Vector{Tv}(undef, nnzC)
-    colptrC[1] = 1
-    # skip sparse_check
-    C = SparseMatrixCSC{Tv, Ti}(mC, nC, colptrC, rowvalC, nzvalC)
+    C = spzeros(Tv, Ti, mC, nC)
+    sizehint!(C, nnz(A)*nnz(B))
     return @inbounds kron!(C, A, B)
 end
 
diff --git a/stdlib/SparseArrays/src/sparsematrix.jl b/stdlib/SparseArrays/src/sparsematrix.jl
index 888db226ddd14..a1ded144ea379 100644
--- a/stdlib/SparseArrays/src/sparsematrix.jl
+++ b/stdlib/SparseArrays/src/sparsematrix.jl
@@ -25,10 +25,9 @@ struct SparseMatrixCSC{Tv,Ti<:Integer} <: AbstractSparseMatrixCSC{Tv,Ti}
 
     function SparseMatrixCSC{Tv,Ti}(m::Integer, n::Integer, colptr::Vector{Ti},
                             rowval::Vector{Ti}, nzval::Vector{Tv}) where {Tv,Ti<:Integer}
-        @noinline throwsz(str, lbl, k) =
-            throw(ArgumentError("number of $str ($lbl) must be ≥ 0, got $k"))
-        m < 0 && throwsz("rows", 'm', m)
-        n < 0 && throwsz("columns", 'n', n)
+        sparse_check_Ti(m, n, Ti)
+        _goodbuffers(Int(m), Int(n), colptr, rowval, nzval) ||
+            throw(ArgumentError("Illegal buffers for SparseMatrixCSC construction $n $colptr $rowval $nzval"))
         new(Int(m), Int(n), colptr, rowval, nzval)
     end
 end
@@ -80,6 +79,15 @@ end
 
 size(S::SparseMatrixCSC) = (getfield(S, :m), getfield(S, :n))
 
+_goodbuffers(S::SparseMatrixCSC) = _goodbuffers(size(S)..., getcolptr(S), getrowval(S), nonzeros(S))
+_checkbuffers(S::SparseMatrixCSC) = (@assert _goodbuffers(S); S)
+
+function _goodbuffers(m, n, colptr, rowval, nzval)
+    (length(colptr) == n + 1 && colptr[end] - 1 == length(rowval) == length(nzval))
+    # stronger check for debugging purposes
+    # && all(issorted(@view rowval[colptr[i]:colptr[i+1]-1]) for i=1:n)
+end
+
 # Define an alias for views of a SparseMatrixCSC which include all rows and a unit range of the columns.
 # Also define a union of SparseMatrixCSC and this view since many methods can be defined efficiently for
 # this union by extracting the fields via the get function: getcolptr, getrowval, and getnzval. The key
@@ -220,6 +228,7 @@ Base.replace_in_print_matrix(A::AbstractSparseMatrix, i::Integer, j::Integer, s:
     Base.isstored(A, i, j) ? s : Base.replace_with_centered_mark(s)
 
 function Base.show(io::IO, ::MIME"text/plain", S::AbstractSparseMatrixCSC)
+    _checkbuffers(S)
     xnnz = nnz(S)
     m, n = size(S)
     print(io, m, "×", n, " ", typeof(S), " with ", xnnz, " stored ",
@@ -295,6 +304,7 @@ function _show_with_braille_patterns(io::IOContext, S::AbstractSparseMatrixCSC)
 end
 
 function Base.show(io::IOContext, S::AbstractSparseMatrixCSC)
+    _checkbuffers(S)
     if max(size(S)...) < 16 && !(get(io, :compact, false)::Bool)
         ioc = IOContext(io, :compact => true)
         println(ioc)
@@ -307,7 +317,7 @@ end
 
 ## Reshape
 
-function sparse_compute_reshaped_colptr_and_rowval(colptrS::Vector{Ti}, rowvalS::Vector{Ti},
+function sparse_compute_reshaped_colptr_and_rowval!(colptrS::Vector{Ti}, rowvalS::Vector{Ti},
                                                    mS::Int, nS::Int, colptrA::Vector{Ti},
                                                    rowvalA::Vector{Ti}, mA::Int, nA::Int) where Ti
     lrowvalA = length(rowvalA)
@@ -350,7 +360,7 @@ function copy(ra::ReshapedArray{<:Any,2,<:AbstractSparseMatrixCSC})
     rowval = similar(rowvals(a))
     nzval = copy(nonzeros(a))
 
-    sparse_compute_reshaped_colptr_and_rowval(colptr, rowval, mS, nS, getcolptr(a), rowvals(a), mA, nA)
+    sparse_compute_reshaped_colptr_and_rowval!(colptr, rowval, mS, nS, getcolptr(a), rowvals(a), mA, nA)
 
     return SparseMatrixCSC(mS, nS, colptr, rowval, nzval)
 end
@@ -377,7 +387,7 @@ function copyto!(A::AbstractSparseMatrixCSC, B::AbstractSparseMatrixCSC)
             copyto!(rowvals(A), rowvals(B))
         else
             # This is like a "reshape B into A".
-            sparse_compute_reshaped_colptr_and_rowval(getcolptr(A), rowvals(A), size(A, 1), size(A, 2), getcolptr(B), rowvals(B), size(B, 1), size(B, 2))
+            sparse_compute_reshaped_colptr_and_rowval!(getcolptr(A), rowvals(A), size(A, 1), size(A, 2), getcolptr(B), rowvals(B), size(B, 1), size(B, 2))
         end
     else
         widelength(A) >= widelength(B) || throw(BoundsError())
@@ -407,10 +417,10 @@ function copyto!(A::AbstractSparseMatrixCSC, B::AbstractSparseMatrixCSC)
         @inbounds for i in 2:length(getcolptr(A))
             getcolptr(A)[i] += nnzB - lastmodptrA
         end
-        sparse_compute_reshaped_colptr_and_rowval(getcolptr(A), rowvals(A), size(A, 1), lastmodcolA-1, getcolptr(B), rowvals(B), size(B, 1), size(B, 2))
+        sparse_compute_reshaped_colptr_and_rowval!(getcolptr(A), rowvals(A), size(A, 1), lastmodcolA-1, getcolptr(B), rowvals(B), size(B, 1), size(B, 2))
     end
     copyto!(nonzeros(A), nonzeros(B))
-    return A
+    return _checkbuffers(A)
 end
 
 copyto!(A::AbstractMatrix, B::AbstractSparseMatrixCSC) = _sparse_copyto!(A, B)
@@ -471,7 +481,7 @@ function _sparsesimilar(S::AbstractSparseMatrixCSC, ::Type{TvNew}, ::Type{TiNew}
 end
 # parent methods for similar that preserves only storage space (for when new dims are 2-d)
 _sparsesimilar(S::AbstractSparseMatrixCSC, ::Type{TvNew}, ::Type{TiNew}, dims::Dims{2}) where {TvNew,TiNew} =
-    SparseMatrixCSC(dims..., fill(one(TiNew), last(dims)+1), similar(rowvals(S), TiNew, 0), similar(nonzeros(S), TvNew, 0))
+    sizehint!(spzeros(TvNew, TiNew, dims...), length(nonzeros(S)))
 # parent method for similar that allocates an empty sparse vector (for when new dims are 1-d)
 _sparsesimilar(S::AbstractSparseMatrixCSC, ::Type{TvNew}, ::Type{TiNew}, dims::Dims{1}) where {TvNew,TiNew} =
     SparseVector(dims..., similar(rowvals(S), TiNew, 0), similar(nonzeros(S), TvNew, 0))
@@ -496,6 +506,12 @@ similar(S::AbstractSparseMatrixCSC, ::Type{TvNew}, ::Type{TiNew}, m::Integer) wh
 similar(S::AbstractSparseMatrixCSC, ::Type{TvNew}, ::Type{TiNew}, m::Integer, n::Integer) where {TvNew,TiNew} =
     _sparsesimilar(S, TvNew, TiNew, (m, n))
 
+function Base.sizehint!(S::SparseMatrixCSC, n::Integer)
+    nhint = min(n, length(S))
+    sizehint!(getrowval(S), nhint)
+    sizehint!(nonzeros(S),  nhint)
+    return S
+end
 
 # converting between SparseMatrixCSC types
 SparseMatrixCSC(S::AbstractSparseMatrixCSC) = copy(S)
@@ -658,6 +674,7 @@ SparseMatrixCSC{Tv,Ti}(M::Transpose{<:Any,<:AbstractSparseMatrixCSC}) where {Tv,
 
 # converting from SparseMatrixCSC to other matrix types
 function Matrix(S::AbstractSparseMatrixCSC{Tv}) where Tv
+    _checkbuffers(S)
     A = Matrix{Tv}(undef, size(S, 1), size(S, 2))
     copyto!(A, S)
     return A
@@ -1016,6 +1033,8 @@ respectively. Simultaneously fixes the one-position-forward shift in `getcolptr(
 """
 @noinline function _distributevals_halfperm!(X::AbstractSparseMatrixCSC{Tv,Ti},
         A::AbstractSparseMatrixCSC{TvA,Ti}, q::AbstractVector{<:Integer}, f::Function) where {Tv,TvA,Ti}
+    resize!(nonzeros(X), nnz(A))
+    resize!(rowvals(X), nnz(A))
     @inbounds for Xi in 1:size(A, 2)
         Aj = q[Xi]
         for Ak in nzrange(A, Aj)
@@ -1035,16 +1054,8 @@ function ftranspose!(X::AbstractSparseMatrixCSC{Tv,Ti}, A::AbstractSparseMatrixC
         throw(DimensionMismatch(string("destination argument `X`'s column count, ",
             "`size(X, 2) (= $(size(X, 2)))`, must match source argument `A`'s row count, `size(A, 1) (= $(size(A, 1)))`")))
     elseif size(X, 1) != size(A, 2)
-        throw(DimensionMismatch(string("destination argument `X`'s row count,
-            `size(X, 1) (= $(size(X, 1)))`, must match source argument `A`'s column count, `size(A, 2) (= $(size(A, 2)))`")))
-    elseif length(rowvals(X)) < nnz(A)
-        throw(ArgumentError(string("the length of destination argument `X`'s `rowval` ",
-            "array, `length(rowvals(X)) (= $(length(rowvals(X))))`, must be greater than or ",
-            "equal to source argument `A`'s allocated entry count, `nnz(A) (= $(nnz(A)))`")))
-    elseif length(nonzeros(X)) < nnz(A)
-        throw(ArgumentError(string("the length of destination argument `X`'s `nzval` ",
-            "array, `length(nonzeros(X)) (= $(length(nonzeros(X))))`, must be greater than or ",
-            "equal to source argument `A`'s allocated entry count, `nnz(A) (= $(nnz(A)))`")))
+        throw(DimensionMismatch(string("destination argument `X`'s row count, ",
+            "`size(X, 1) (= $(size(X, 1)))`, must match source argument `A`'s column count, `size(A, 2) (= $(size(A, 2)))`")))
     end
     halfperm!(X, A, 1:size(A, 2), f)
 end
@@ -1055,8 +1066,9 @@ adjoint!(X::AbstractSparseMatrixCSC{Tv,Ti}, A::AbstractSparseMatrixCSC{Tv,Ti}) w
 function ftranspose(A::AbstractSparseMatrixCSC{TvA,Ti}, f::Function, eltype::Type{Tv} = TvA) where {Tv,TvA,Ti}
     X = SparseMatrixCSC(size(A, 2), size(A, 1),
                         ones(Ti, size(A, 1)+1),
-                        Vector{Ti}(undef, nnz(A)),
-                        Vector{Tv}(undef, nnz(A)))
+                        Vector{Ti}(undef, 0),
+                        Vector{Tv}(undef, 0))
+    sizehint!(X, nnz(A))
     halfperm!(X, A, 1:size(A, 2), f)
 end
 adjoint(A::AbstractSparseMatrixCSC) = Adjoint(A)
@@ -1274,10 +1286,11 @@ function permute!(X::AbstractSparseMatrixCSC{Tv,Ti}, A::AbstractSparseMatrixCSC{
         p::AbstractVector{<:Integer}, q::AbstractVector{<:Integer}) where {Tv,Ti}
     _checkargs_sourcecompatdest_permute!(A, X)
     _checkargs_sourcecompatperms_permute!(A, p, q)
-    C = SparseMatrixCSC(size(A, 2), size(A, 1),
-                        ones(Ti, size(A, 1) + 1),
-                        Vector{Ti}(undef, nnz(A)),
-                        Vector{Tv}(undef, nnz(A)))
+    # bypass strict buffer checking
+    C = spzeros(Tv, Ti, size(A,2), size(A,1))
+    resize!(getrowval(C), nnz(A))
+    resize!(getnzval(C), nnz(A))
+
     _checkargs_permutationsvalid_permute!(p, getcolptr(C), q, getcolptr(X))
     unchecked_noalias_permute!(X, A, p, q, C)
 end
@@ -1293,10 +1306,9 @@ end
 function permute!(A::AbstractSparseMatrixCSC{Tv,Ti}, p::AbstractVector{<:Integer},
         q::AbstractVector{<:Integer}) where {Tv,Ti}
     _checkargs_sourcecompatperms_permute!(A, p, q)
-    C = SparseMatrixCSC(size(A, 2), size(A, 1),
-                        ones(Ti, size(A, 1) + 1),
-                        Vector{Ti}(undef, nnz(A)),
-                        Vector{Tv}(undef, nnz(A)))
+    C = spzeros(Tv, Ti, size(A,2), size(A,1))
+    resize!(getrowval(C), nnz(A))
+    resize!(getnzval(C), nnz(A))
     workcolptr = Vector{Ti}(undef, size(A, 2) + 1)
     _checkargs_permutationsvalid_permute!(p, getcolptr(C), q, workcolptr)
     unchecked_aliasing_permute!(A, p, q, C, workcolptr)
@@ -1355,14 +1367,14 @@ julia> permute(A, [1, 2, 3, 4], [4, 3, 2, 1])
 function permute(A::AbstractSparseMatrixCSC{Tv,Ti}, p::AbstractVector{<:Integer},
         q::AbstractVector{<:Integer}) where {Tv,Ti}
     _checkargs_sourcecompatperms_permute!(A, p, q)
-    X = SparseMatrixCSC(size(A, 1), size(A, 2),
-                        ones(Ti, size(A, 2) + 1),
-                        Vector{Ti}(undef, nnz(A)),
-                        Vector{Tv}(undef, nnz(A)))
-    C = SparseMatrixCSC(size(A, 2), size(A, 1),
-                        ones(Ti, size(A, 1) + 1),
-                        Vector{Ti}(undef, nnz(A)),
-                        Vector{Tv}(undef, nnz(A)))
+    # bypass strict buffer checking
+    X = spzeros(Tv, Ti, size(A,1), size(A,2))
+    resize!(getrowval(X), nnz(A))
+    resize!(getnzval(X), nnz(A))
+    # bypass strict buffer checking
+    C = spzeros(Tv, Ti, size(A,2), size(A,1))
+    resize!(getrowval(C), nnz(A))
+    resize!(getnzval(C), nnz(A))
     _checkargs_permutationsvalid_permute!(p, getcolptr(C), q, getcolptr(X))
     unchecked_noalias_permute!(X, A, p, q, C)
 end
@@ -1455,6 +1467,7 @@ For an out-of-place version, see [`dropzeros`](@ref). For
 algorithmic information, see `fkeep!`.
 """
 dropzeros!(A::AbstractSparseMatrixCSC) = fkeep!(A, (i, j, x) -> !iszero(x))
+
 """
     dropzeros(A::AbstractSparseMatrixCSC;)
 
@@ -2480,7 +2493,7 @@ function permute_rows!(S::AbstractSparseMatrixCSC{Tv,Ti}, pI::Vector{Int}) where
             k += 1
         end
     end
-    S
+    return _checkbuffers(S)
 end
 
 function getindex_general(A::AbstractSparseMatrixCSC, I::AbstractVector, J::AbstractVector)
@@ -2634,6 +2647,7 @@ function Base.fill!(V::SubArray{Tv, <:Any, <:AbstractSparseMatrixCSC{Tv}, <:Tupl
     else
         _spsetnz_setindex!(A, convert(Tv, x), I, J)
     end
+    return _checkbuffers(A)
 end
 """
 Helper method for immediately preceding fill! method. For all (i,j) such that i in I and
@@ -2917,7 +2931,7 @@ function setindex!(A::AbstractSparseMatrixCSC{Tv,Ti}, V::AbstractVecOrMat, Ix::U
     deleteat!(rowvalA, colptrA[end]:length(rowvalA))
     deleteat!(nzvalA, colptrA[end]:length(nzvalA))
 
-    return A
+    return _checkbuffers(A)
 end
 
 # Logical setindex!
@@ -3026,7 +3040,7 @@ function setindex!(A::AbstractSparseMatrixCSC, x::AbstractArray, I::AbstractMatr
             deleteat!(rowvalB, bidx:n)
         end
     end
-    A
+    return _checkbuffers(A)
 end
 
 function setindex!(A::AbstractSparseMatrixCSC, x::AbstractArray, Ix::AbstractVector{<:Integer})
@@ -3137,7 +3151,7 @@ function setindex!(A::AbstractSparseMatrixCSC, x::AbstractArray, Ix::AbstractVec
             deleteat!(rowvalB, bidx:n)
         end
     end
-    A
+    return _checkbuffers(A)
 end
 
 ## dropstored! methods
@@ -3173,7 +3187,7 @@ function dropstored!(A::AbstractSparseMatrixCSC, i::Integer, j::Integer)
             @inbounds getcolptr(A)[m] -= 1
         end
     end
-    return A
+    return _checkbuffers(A)
 end
 """
     dropstored!(A::AbstractSparseMatrixCSC, I::AbstractVector{<:Integer}, J::AbstractVector{<:Integer})
@@ -3260,7 +3274,7 @@ function dropstored!(A::AbstractSparseMatrixCSC,
         deleteat!(rowvalA, rowidx:nnzA)
         deleteat!(nzvalA, rowidx:nnzA)
     end
-    return A
+    return _checkbuffers(A)
 end
 dropstored!(A::AbstractSparseMatrixCSC, i::Integer, J::AbstractVector{<:Integer}) = dropstored!(A, [i], J)
 dropstored!(A::AbstractSparseMatrixCSC, I::AbstractVector{<:Integer}, j::Integer) = dropstored!(A, I, [j])
@@ -3837,7 +3851,7 @@ function circshift!(O::AbstractSparseMatrixCSC, X::AbstractSparseMatrixCSC, (r,c
     @inbounds for i=1:size(O, 2)
         subvector_shifter!(rowvals(O), nonzeros(O), getcolptr(O)[i], getcolptr(O)[i+1]-1, size(O, 1), r)
     end
-    return O
+    return _checkbuffers(O)
 end
 
 circshift!(O::AbstractSparseMatrixCSC, X::AbstractSparseMatrixCSC, (r,)::Base.DimsInteger{1}) = circshift!(O, X, (r,0))
diff --git a/stdlib/SparseArrays/src/sparsevector.jl b/stdlib/SparseArrays/src/sparsevector.jl
index 52142553e5019..f893fb04eadf3 100644
--- a/stdlib/SparseArrays/src/sparsevector.jl
+++ b/stdlib/SparseArrays/src/sparsevector.jl
@@ -84,6 +84,13 @@ rowvals(x::SparseVectorUnion) = nonzeroinds(x)
 indtype(x::SparseColumnView) = indtype(parent(x))
 indtype(x::SparseVectorView) = indtype(parent(x))
 
+
+function Base.sizehint!(v::SparseVector, newlen::Integer)
+    sizehint!(nonzeroinds(v), newlen)
+    sizehint!(nonzeros(v), newlen)
+    return v
+end
+
 ## similar
 #
 # parent method for similar that preserves stored-entry structure (for when new and old dims match)
@@ -92,10 +99,11 @@ _sparsesimilar(S::SparseVector, ::Type{TvNew}, ::Type{TiNew}) where {TvNew,TiNew
 # parent method for similar that preserves nothing (for when new dims are 1-d)
 _sparsesimilar(S::SparseVector, ::Type{TvNew}, ::Type{TiNew}, dims::Dims{1}) where {TvNew,TiNew} =
     SparseVector(dims..., similar(nonzeroinds(S), TiNew, 0), similar(nonzeros(S), TvNew, 0))
-# parent method for similar that preserves storage space (for when new dims are 2-d)
-_sparsesimilar(S::SparseVector, ::Type{TvNew}, ::Type{TiNew}, dims::Dims{2}) where {TvNew,TiNew} =
-    SparseMatrixCSC(dims..., fill(one(TiNew), last(dims)+1), similar(nonzeroinds(S), TiNew, 0), similar(nonzeros(S), TvNew, 0))
-
+# parent method for similar that preserves storage space (for old and new dims differ, and new is 2d)
+function _sparsesimilar(S::SparseVector, ::Type{TvNew}, ::Type{TiNew}, dims::Dims{2}) where {TvNew,TiNew}
+    S1 = SparseMatrixCSC(dims..., fill(one(TiNew), last(dims)+1), similar(nonzeroinds(S), TiNew, 0), similar(nonzeros(S), TvNew, 0))
+    return sizehint!(S1, min(widelength(S1), length(nonzeroinds(S))))
+end
 # The following methods hook into the AbstractArray similar hierarchy. The first method
 # covers similar(A[, Tv]) calls, which preserve stored-entry structure, and the latter
 # methods cover similar(A[, Tv], shape...) calls, which preserve nothing if the dims
diff --git a/stdlib/SparseArrays/test/sparse.jl b/stdlib/SparseArrays/test/sparse.jl
index a622d2bc8bcc0..8151dba862fdd 100644
--- a/stdlib/SparseArrays/test/sparse.jl
+++ b/stdlib/SparseArrays/test/sparse.jl
@@ -48,7 +48,7 @@ end
     S = sparse(I, 3, 3)
     fill!(S, 0)
     @test iszero(S)  # test success with stored zeros via fill!
-    @test iszero(SparseMatrixCSC(2, 2, [1,2,3], [1,2], [0,0,1])) # test success with nonzeros beyond data range
+    @test_throws ArgumentError iszero(SparseMatrixCSC(2, 2, [1,2,3], [1,2], [0,0,1])) # test failure with nonzeros beyond data range
 end
 @testset "isone specialization for SparseMatrixCSC" begin
     @test isone(sparse(I, 3, 3))    # test success
@@ -673,8 +673,6 @@ end
     @testset "common error checking of [c]transpose! methods (ftranspose!)" begin
         @test_throws DimensionMismatch transpose!(A[:, 1:(smalldim - 1)], A)
         @test_throws DimensionMismatch transpose!(A[1:(smalldim - 1), 1], A)
-        @test_throws ArgumentError transpose!((B = similar(A); resize!(rowvals(B), nnz(A) - 1); B), A)
-        @test_throws ArgumentError transpose!((B = similar(A); resize!(nonzeros(B), nnz(A) - 1); B), A)
     end
     @testset "common error checking of permute[!] methods / source-perm compat" begin
         @test_throws DimensionMismatch permute(A, p[1:(end - 1)], q)
@@ -2416,19 +2414,6 @@ end
     @test String(take!(io)) == "⠛⠛"
 end
 
-@testset "check buffers" for n in 1:3
-    local A
-    rowval = [1,2,3]
-    nzval1  = Int[]
-    nzval2  = [1,1,1]
-    A = SparseMatrixCSC(n, n, [1:n+1;], rowval, nzval1)
-    @test nnz(A) == n
-    @test_throws BoundsError A[n,n]
-    A = SparseMatrixCSC(n, n, [1:n+1;], rowval, nzval2)
-    @test nnz(A) == n
-    @test A      == Matrix(I, n, n)
-end
-
 @testset "reverse search direction if step < 0 #21986" begin
     local A, B
     A = guardseed(1234) do
@@ -2530,8 +2515,6 @@ end
     # count should throw for sparse arrays for which zero(eltype) does not exist
     @test_throws MethodError count(SparseMatrixCSC(2, 2, Int[1, 2, 3], Int[1, 2], Any[true, true]))
     @test_throws MethodError count(SparseVector(2, Int[1], Any[true]))
-    # count should run only over nonzeros(S)[1:nnz(S)], not nonzeros(S) in full
-    @test count(SparseMatrixCSC(2, 2, Int[1, 2, 3], Int[1, 2], Bool[true, true, true])) == 2
 end
 
 @testset "sparse findprev/findnext operations" begin
@@ -2599,15 +2582,6 @@ end
     @test sum(s, dims=2) == reshape([1, 2, 3], 3, 1)
 end
 
-@testset "mapreduce of sparse matrices with trailing elements in nzval #26534" begin
-    B = SparseMatrixCSC{Int,Int}(2, 3,
-        [1, 3, 4, 5],
-        [1, 2, 1, 2, 999, 999, 999, 999],
-        [1, 2, 3, 6, 999, 999, 999, 999]
-    )
-    @test maximum(B) == 6
-end
-
 _length_or_count_or_five(::Colon) = 5
 _length_or_count_or_five(x::AbstractVector{Bool}) = count(x)
 _length_or_count_or_five(x) = length(x)
@@ -2883,19 +2857,6 @@ end
     @test sparse(deepwrap(A)) == Matrix(deepwrap(B))
 end
 
-@testset "unary operations on matrices where length(nzval)>nnz" begin
-    # this should create a sparse matrix with length(nzval)>nnz
-    A = SparseMatrixCSC(Complex{BigInt}[1+im 2+2im]')'[1:1, 2:2]
-    # ...ensure it does! If necessary, the test needs to be updated to use
-    # another mechanism to create a suitable A.
-    resize!(nonzeros(A), 2)
-    @assert length(nonzeros(A)) > nnz(A)
-    @test -A == fill(-2-2im, 1, 1)
-    @test conj(A) == fill(2-2im, 1, 1)
-    conj!(A)
-    @test A == fill(2-2im, 1, 1)
-end
-
 @testset "issue #31453" for T in [UInt8, Int8, UInt16, Int16, UInt32, Int32]
     i = Int[1, 2]
     j = Int[2, 1]
diff --git a/stdlib/SparseArrays/test/sparsevector.jl b/stdlib/SparseArrays/test/sparsevector.jl
index 6d29633bb04e0..03aed95a43a83 100644
--- a/stdlib/SparseArrays/test/sparsevector.jl
+++ b/stdlib/SparseArrays/test/sparsevector.jl
@@ -1419,14 +1419,14 @@ end
     # test entry points to similar with entry type, index type, and non-Dims shape specification
     @test similar(A, Float32, Int8, 6, 6) == similar(A, Float32, Int8, (6, 6))
     @test similar(A, Float32, Int8, 6) == similar(A, Float32, Int8, (6,))
-    # test similar with Dims{2} specification (preserves storage space only, not stored-entry structure)
+    # test similar with Dims{2} specification (preserves allocated storage space only, not stored-entry structure)
     simA = similar(A, (6,6))
     @test typeof(simA) == SparseMatrixCSC{eltype(nonzeros(A)),eltype(nonzeroinds(A))}
     @test size(simA) == (6,6)
     @test getcolptr(simA) == fill(1, 6+1)
     @test length(rowvals(simA)) == 0
     @test length(nonzeros(simA)) == 0
-    # test similar with entry type and Dims{2} specification (preserves storage space only)
+    # test similar with entry type and Dims{2} specification (preserves allocated storage space only)
     simA = similar(A, Float32, (6,6))
     @test typeof(simA) == SparseMatrixCSC{Float32,eltype(nonzeroinds(A))}
     @test size(simA) == (6,6)
diff --git a/stdlib/SuiteSparse/src/cholmod.jl b/stdlib/SuiteSparse/src/cholmod.jl
index ef14709eb076c..85d7b6b08dce8 100644
--- a/stdlib/SuiteSparse/src/cholmod.jl
+++ b/stdlib/SuiteSparse/src/cholmod.jl
@@ -1096,60 +1096,46 @@ function Vector{T}(D::Dense{T}) where T
 end
 Vector(D::Dense{T}) where {T} = Vector{T}(D)
 
+function _extract_args(s)
+    return (s.nrow, s.ncol, increment(unsafe_wrap(Array, s.p, (s.ncol + 1,), own = false)),
+        increment(unsafe_wrap(Array, s.i, (s.nzmax,), own = false)),
+        copy(unsafe_wrap(Array, s.x, (s.nzmax,), own = false)))
+end
+
+# Trim extra elements in rowval and nzval left around sometimes by CHOLMOD rutines
+function _trim_nz_builder!(m, n, colptr, rowval, nzval)
+    l = colptr[end] - 1
+    resize!(rowval, l)
+    resize!(nzval, l)
+    SparseMatrixCSC(m, n, colptr, rowval, nzval)
+end
+
 function SparseMatrixCSC{Tv,SuiteSparse_long}(A::Sparse{Tv}) where Tv
     s = unsafe_load(pointer(A))
     if s.stype != 0
         throw(ArgumentError("matrix has stype != 0. Convert to matrix " *
             "with stype == 0 before converting to SparseMatrixCSC"))
     end
-
-    B = SparseMatrixCSC(s.nrow, s.ncol,
-        increment(unsafe_wrap(Array, s.p, (s.ncol + 1,), own = false)),
-        increment(unsafe_wrap(Array, s.i, (s.nzmax,), own = false)),
-        copy(unsafe_wrap(Array, s.x, (s.nzmax,), own = false)))
-
-    if s.sorted == 0
-        return SparseArrays.sortSparseMatrixCSC!(B)
-    else
-        return B
-    end
+    args = _extract_args(s)
+    s.sorted == 0 && sortBuffers!(args...);
+    return _trim_nz_builder!(args...)
 end
 
 function Symmetric{Float64,SparseMatrixCSC{Float64,SuiteSparse_long}}(A::Sparse{Float64})
     s = unsafe_load(pointer(A))
-    if !issymmetric(A)
-        throw(ArgumentError("matrix is not symmetric"))
-    end
-
-    B = Symmetric(SparseMatrixCSC(s.nrow, s.ncol,
-        increment(unsafe_wrap(Array, s.p, (s.ncol + 1,), own = false)),
-        increment(unsafe_wrap(Array, s.i, (s.nzmax,), own = false)),
-        copy(unsafe_wrap(Array, s.x, (s.nzmax,), own = false))), s.stype > 0 ? :U : :L)
-
-    if s.sorted == 0
-        return SparseArrays.sortSparseMatrixCSC!(B.data)
-    else
-        return B
-    end
+    issymmetric(A) || throw(ArgumentError("matrix is not symmetric"))
+    args = _extract_args(s)
+    s.sorted == 0 && sortBuffers!(args...)
+    Symmetric(_trim_nz_builder!(args...), s.stype > 0 ? :U : :L)
 end
 convert(T::Type{Symmetric{Float64,SparseMatrixCSC{Float64,SuiteSparse_long}}}, A::Sparse{Float64}) = T(A)
 
 function Hermitian{Tv,SparseMatrixCSC{Tv,SuiteSparse_long}}(A::Sparse{Tv}) where Tv<:VTypes
     s = unsafe_load(pointer(A))
-    if !ishermitian(A)
-        throw(ArgumentError("matrix is not Hermitian"))
-    end
-
-    B = Hermitian(SparseMatrixCSC(s.nrow, s.ncol,
-        increment(unsafe_wrap(Array, s.p, (s.ncol + 1,), own = false)),
-        increment(unsafe_wrap(Array, s.i, (s.nzmax,), own = false)),
-        copy(unsafe_wrap(Array, s.x, (s.nzmax,), own = false))), s.stype > 0 ? :U : :L)
-
-    if s.sorted == 0
-        return SparseArrays.sortSparseMatrixCSC!(B.data)
-    else
-        return B
-    end
+    ishermitian(A) || throw(ArgumentError("matrix is not Hermitian"))
+    args = _extract_args(s)
+    s.sorted == 0 && sortBuffers!(args...)
+    Hermitian(_trim_nz_builder!(args...), s.stype > 0 ? :U : :L)
 end
 convert(T::Type{Hermitian{Tv,SparseMatrixCSC{Tv,SuiteSparse_long}}}, A::Sparse{Tv}) where {Tv<:VTypes} = T(A)
 
@@ -1158,14 +1144,14 @@ function sparse(A::Sparse{Float64}) # Notice! Cannot be type stable because of s
     if s.stype == 0
         return SparseMatrixCSC{Float64,SuiteSparse_long}(A)
     end
-    return Symmetric{Float64,SparseMatrixCSC{Float64,SuiteSparse_long}}(A)
+    Symmetric{Float64,SparseMatrixCSC{Float64,SuiteSparse_long}}(A)
 end
 function sparse(A::Sparse{ComplexF64}) # Notice! Cannot be type stable because of stype
     s = unsafe_load(pointer(A))
     if s.stype == 0
         return SparseMatrixCSC{ComplexF64,SuiteSparse_long}(A)
     end
-    return Hermitian{ComplexF64,SparseMatrixCSC{ComplexF64,SuiteSparse_long}}(A)
+    Hermitian{ComplexF64,SparseMatrixCSC{ComplexF64,SuiteSparse_long}}(A)
 end
 function sparse(F::Factor)
     s = unsafe_load(pointer(F))
@@ -1177,7 +1163,8 @@ function sparse(F::Factor)
         L, d = getLd!(LD)
         A = (L * Diagonal(d)) * L'
     end
-    SparseArrays.sortSparseMatrixCSC!(A)
+    # no need to sort buffers here, as A isa SparseMatrixCSC
+    # and it is taken care in sparse
     p = get_perm(F)
     if p != [1:s.n;]
         pinv = Vector{Int}(undef, length(p))
@@ -1970,4 +1957,58 @@ end
 (*)(A::SparseVecOrMat{Float64,Ti},
     B::Hermitian{Float64,SparseMatrixCSC{Float64,Ti}}) where {Ti} = sparse(Sparse(A)*Sparse(B))
 
+# Sort all the indices in each column for the construction of a CSC sparse matrix
+# sortBuffers!(A, sortindices = :sortcols)        # Sort each column with sort()
+function sortBuffers!(m, n, colptr::Vector{Ti}, rowval::Vector{Ti}, nzval::Vector{Tv}) where {Ti <: Integer, Tv}
+    index = Base.zeros(Ti, m)
+    row = Base.zeros(Ti, m)
+    val = Base.zeros(Tv, m)
+
+    perm = Base.Perm(Base.ord(isless, identity, false, Base.Order.Forward), row)
+
+    @inbounds for i = 1:n
+        nzr = colptr[i]:colptr[i+1]-1
+        numrows = length(nzr)
+        if numrows <= 1
+            continue
+        elseif numrows == 2
+            f = first(nzr)
+            s = f+1
+            if rowval[f] > rowval[s]
+                rowval[f], rowval[s] = rowval[s], rowval[f]
+                nzval[f],  nzval[s]  = nzval[s],  nzval[f]
+            end
+            continue
+        end
+        resize!(row, numrows)
+        resize!(index, numrows)
+
+        jj = 1
+        @simd for j = nzr
+            row[jj] = rowval[j]
+            val[jj] = nzval[j]
+            jj += 1
+        end
+
+        if numrows <= 16
+            alg = Base.Sort.InsertionSort
+        else
+            alg = Base.Sort.QuickSort
+        end
+
+        # Reset permutation
+        index .= 1:numrows
+
+        Base.sort!(index, alg, perm)
+
+        jj = 1
+        @simd for j = nzr
+            rowval[j] = row[index[jj]]
+            nzval[j] = val[index[jj]]
+            jj += 1
+        end
+    end
+end
+
+
 end #module
diff --git a/stdlib/SuiteSparse/test/cholmod.jl b/stdlib/SuiteSparse/test/cholmod.jl
index b0230f97eae2e..3b02e02af8204 100644
--- a/stdlib/SuiteSparse/test/cholmod.jl
+++ b/stdlib/SuiteSparse/test/cholmod.jl
@@ -794,12 +794,13 @@ end
     end
 end
 
-@testset "Check inputs to Sparse. Related to #20024" for A_ in (
-    SparseMatrixCSC(2, 2, [1, 2, 3], CHOLMOD.SuiteSparse_long[1,2], Float64[]),
-    SparseMatrixCSC(2, 2, [1, 2, 3], CHOLMOD.SuiteSparse_long[1,2], Float64[1.0]))
-    args = (size(A_)..., getcolptr(A_) .- 1, rowvals(A_) .- 1, nonzeros(A_))
-    @test_throws ArgumentError CHOLMOD.Sparse(args...)
-    @test_throws ArgumentError CHOLMOD.Sparse(A_)
+@testset "Check inputs to Sparse. Related to #20024" for t_ in (
+    (2, 2, [1, 2], CHOLMOD.SuiteSparse_long[], Float64[]),
+    (2, 2, [1, 2, 3], CHOLMOD.SuiteSparse_long[1], Float64[]),
+    (2, 2, [1, 2, 3], CHOLMOD.SuiteSparse_long[], Float64[1.0]),
+    (2, 2, [1, 2, 3], CHOLMOD.SuiteSparse_long[1], Float64[1.0]))
+    @test_throws ArgumentError SparseMatrixCSC(t_...)
+    @test_throws ArgumentError CHOLMOD.Sparse(t_[1], t_[2], t_[3] .- 1, t_[4] .- 1, t_[5])
 end
 
 @testset "sparse right multiplication of Symmetric and Hermitian matrices #21431" begin

From 3496fd6e5e74b01c30d9ad8662118b4281130eec Mon Sep 17 00:00:00 2001
From: Alfredo Braunstein <alfredo.braunstein@polito.it>
Date: Sun, 18 Apr 2021 18:56:18 +0200
Subject: [PATCH 2/3] remove two more tests

---
 stdlib/SparseArrays/test/sparse.jl | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/stdlib/SparseArrays/test/sparse.jl b/stdlib/SparseArrays/test/sparse.jl
index 8151dba862fdd..f2754ba5ade81 100644
--- a/stdlib/SparseArrays/test/sparse.jl
+++ b/stdlib/SparseArrays/test/sparse.jl
@@ -2906,14 +2906,8 @@ end
     @test_throws ArgumentError SparseMatrixCSC(10, 3, [1,2,1,2], Int[], Float64[])
     # rowwal (and nzval) short
     @test_throws ArgumentError SparseMatrixCSC(10, 3, [1,2,2,4], [1,2], Float64[])
-    # nzval short
-    @test SparseMatrixCSC(10, 3, [1,2,2,4], [1,2,3], Float64[]) !== nothing
-    # length(rowval) >= typemax
-    @test_throws ArgumentError SparseMatrixCSC(5, 1, Int8[1,2], fill(Int8(1),127), Int[1,2,3])
-    @test SparseMatrixCSC{Int,Int8}(5, 1, Int8[1,2], fill(Int8(1),127), Int[1,2,3]) != 0
     # length(nzval) >= typemax
-    @test_throws ArgumentError SparseMatrixCSC(5, 1, Int8[1,2], Int8[1], fill(7, 127))
-    @test SparseMatrixCSC{Int,Int8}(5, 1, Int8[1,2], Int8[1], fill(7, 127)) != 0
+    @test_throws ArgumentError SparseMatrixCSC(5, 1, Int8[1,2], fill(Int8(1), 127), fill(7, 127))
 
     # length(I) >= typemax
     @test_throws ArgumentError sparse(UInt8.(1:255), fill(UInt8(1), 255), fill(1, 255))

From 46e110fb75f63b83ed7dec768349a67d6a46826c Mon Sep 17 00:00:00 2001
From: Alfredo Braunstein <alfredo.braunstein@polito.it>
Date: Mon, 19 Apr 2021 09:21:06 +0200
Subject: [PATCH 3/3] use widelength in sizehint! to cope with large matrices
 in 32 bit systems

---
 stdlib/SparseArrays/src/sparsematrix.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/SparseArrays/src/sparsematrix.jl b/stdlib/SparseArrays/src/sparsematrix.jl
index a1ded144ea379..9ca3a60dc521f 100644
--- a/stdlib/SparseArrays/src/sparsematrix.jl
+++ b/stdlib/SparseArrays/src/sparsematrix.jl
@@ -507,7 +507,7 @@ similar(S::AbstractSparseMatrixCSC, ::Type{TvNew}, ::Type{TiNew}, m::Integer, n:
     _sparsesimilar(S, TvNew, TiNew, (m, n))
 
 function Base.sizehint!(S::SparseMatrixCSC, n::Integer)
-    nhint = min(n, length(S))
+    nhint = min(n, widelength(S))
     sizehint!(getrowval(S), nhint)
     sizehint!(nonzeros(S),  nhint)
     return S