effects: power-up effects analysis for array operations (#47154)

Mostly by making use of newly added `:inaccessiblememonly` effect
property.
Now we can fold simple vector operations like:
```julia
julia> function simple_vec_ops(T, op!, op, xs...)
           a = T[]
           op!(a, xs...)
           return op(a)
       end;
simple_vec_ops (generic function with 1 method)

julia> for T = Any[Int,Any], op! = Any[push!,pushfirst!], op = Any[length,size],
           xs = Any[(Int,), (Int,Int,)]
           let effects = Base.infer_effects(simple_vec_ops, (Type{T},typeof(op!),typeof(op),xs...))
               @test Core.Compiler.is_foldable(effects)
           end
       end

julia> code_typed() do
           simple_vec_ops(Any, push!, length, Any,nothing,Core.Const(1))
       end
1-element Vector{Any}:
 CodeInfo(
1 ─     return 3
) => Int64
```

Author: aviatesk

base/array.jl

@@ -122,8 +122,50 @@ const DenseVecOrMat{T} = Union{DenseVector{T}, DenseMatrix{T}}
 
 using Core: arraysize, arrayset, const_arrayref
 
+"""
+    @_safeindex
+
+This internal macro converts:
+- `getindex(xs::Tuple, )` -> `__inbounds_getindex(args...)`
+- `setindex!(xs::Vector, args...)` -> `__inbounds_setindex!(xs, args...)`
+to tell the compiler that indexing operations within the applied expression are always
+inbounds and do not need to taint `:consistent` and `:nothrow`.
+"""
+macro _safeindex(ex)
+    return esc(_safeindex(__module__, ex))
+end
+function _safeindex(__module__, ex)
+    isa(ex, Expr) || return ex
+    if ex.head === :(=)
+        lhs = arrayref(true, ex.args, 1)
+        if isa(lhs, Expr) && lhs.head === :ref # xs[i] = x
+            rhs = arrayref(true, ex.args, 2)
+            xs = arrayref(true, lhs.args, 1)
+            args = Vector{Any}(undef, length(lhs.args)-1)
+            for i = 2:length(lhs.args)
+                arrayset(true, args, _safeindex(__module__, arrayref(true, lhs.args, i)), i-1)
+            end
+            return Expr(:call, GlobalRef(__module__, :__inbounds_setindex!), xs, _safeindex(__module__, rhs), args...)
+        end
+    elseif ex.head === :ref # xs[i]
+        return Expr(:call, GlobalRef(__module__, :__inbounds_getindex), ex.args...)
+    end
+    args = Vector{Any}(undef, length(ex.args))
+    for i = 1:length(ex.args)
+        arrayset(true, args, _safeindex(__module__, arrayref(true, ex.args, i)), i)
+    end
+    return Expr(ex.head, args...)
+end
+
 vect() = Vector{Any}()
-vect(X::T...) where {T} = T[ X[i] for i = 1:length(X) ]
+function vect(X::T...) where T
+    @_terminates_locally_meta
+    vec = Vector{T}(undef, length(X))
+    @_safeindex for i = 1:length(X)
+        vec[i] = X[i]
+    end
+    return vec
+end
 
 """
     vect(X...)
@@ -321,7 +363,7 @@ end
 
 function _copyto_impl!(dest::Array, doffs::Integer, src::Array, soffs::Integer, n::Integer)
     n == 0 && return dest
-    n > 0 || _throw_argerror()
+    n > 0 || _throw_argerror("Number of elements to copy must be nonnegative.")
     @boundscheck checkbounds(dest, doffs:doffs+n-1)
     @boundscheck checkbounds(src, soffs:soffs+n-1)
     unsafe_copyto!(dest, doffs, src, soffs, n)
@@ -331,10 +373,7 @@ end
 # Outlining this because otherwise a catastrophic inference slowdown
 # occurs, see discussion in #27874.
 # It is also mitigated by using a constant string.
-function _throw_argerror()
-    @noinline
-    throw(ArgumentError("Number of elements to copy must be nonnegative."))
-end
+_throw_argerror(s) = (@noinline; throw(ArgumentError(s)))
 
 copyto!(dest::Array, src::Array) = copyto!(dest, 1, src, 1, length(src))
 
@@ -397,9 +436,11 @@ julia> getindex(Int8, 1, 2, 3)
 ```
 """
 function getindex(::Type{T}, vals...) where T
+    @inline
+    @_effect_free_terminates_locally_meta
     a = Vector{T}(undef, length(vals))
     if vals isa NTuple
-        @inbounds for i in 1:length(vals)
+        @_safeindex for i in 1:length(vals)
             a[i] = vals[i]
         end
     else
@@ -412,9 +453,21 @@ function getindex(::Type{T}, vals...) where T
     return a
 end
 
+# safe version
+function getindex(::Type{T}, vals::T...) where T
+    @inline
+    @_effect_free_terminates_locally_meta
+    a = Vector{T}(undef, length(vals))
+    @_safeindex for i in 1:length(vals)
+        a[i] = vals[i]
+    end
+    return a
+end
+
 function getindex(::Type{Any}, @nospecialize vals...)
+    @_effect_free_terminates_locally_meta
     a = Vector{Any}(undef, length(vals))
-    @inbounds for i = 1:length(vals)
+    @_safeindex for i = 1:length(vals)
         a[i] = vals[i]
     end
     return a
@@ -966,10 +1019,16 @@ Dict{String, Int64} with 2 entries:
 """
 function setindex! end
 
-@eval setindex!(A::Array{T}, x, i1::Int) where {T} = arrayset($(Expr(:boundscheck)), A, convert(T,x)::T, i1)
+@eval setindex!(A::Array{T}, x, i1::Int) where {T} =
+    arrayset($(Expr(:boundscheck)), A, convert(T,x)::T, i1)
 @eval setindex!(A::Array{T}, x, i1::Int, i2::Int, I::Int...) where {T} =
     (@inline; arrayset($(Expr(:boundscheck)), A, convert(T,x)::T, i1, i2, I...))
 
+__inbounds_setindex!(A::Array{T}, x, i1::Int) where {T} =
+    arrayset(false, A, convert(T,x)::T, i1)
+__inbounds_setindex!(A::Array{T}, x, i1::Int, i2::Int, I::Int...) where {T} =
+    (@inline; arrayset(false, A, convert(T,x)::T, i1, i2, I...))
+
 # This is redundant with the abstract fallbacks but needed and helpful for bootstrap
 function setindex!(A::Array, X::AbstractArray, I::AbstractVector{Int})
     @_propagate_inbounds_meta
@@ -1055,26 +1114,27 @@ See also [`pushfirst!`](@ref).
 """
 function push! end
 
-function push!(a::Array{T,1}, item) where T
+function push!(a::Vector{T}, item) where T
     # convert first so we don't grow the array if the assignment won't work
     itemT = convert(T, item)
     _growend!(a, 1)
-    @inbounds a[end] = itemT
+    @_safeindex a[length(a)] = itemT
     return a
 end
 
 # specialize and optimize the single argument case
 function push!(a::Vector{Any}, @nospecialize x)
     _growend!(a, 1)
-    arrayset(true, a, x, length(a))
+    @_safeindex a[length(a)] = x
     return a
 end
 function push!(a::Vector{Any}, @nospecialize x...)
+    @_terminates_locally_meta
     na = length(a)
     nx = length(x)
     _growend!(a, nx)
-    for i = 1:nx
-        arrayset(true, a, x[i], na+i)
+    @_safeindex for i = 1:nx
+        a[na+i] = x[i]
     end
     return a
 end
@@ -1129,10 +1189,11 @@ push!(a::AbstractVector, iter...) = append!(a, iter)
 append!(a::AbstractVector, iter...) = foldl(append!, iter, init=a)
 
 function _append!(a, ::Union{HasLength,HasShape}, iter)
+    @_terminates_locally_meta
     n = length(a)
     i = lastindex(a)
     resize!(a, n+Int(length(iter))::Int)
-    @inbounds for (i, item) in zip(i+1:lastindex(a), iter)
+    @_safeindex for (i, item) in zip(i+1:lastindex(a), iter)
         a[i] = item
     end
     a
@@ -1194,12 +1255,13 @@ pushfirst!(a::Vector, iter...) = prepend!(a, iter)
 prepend!(a::AbstractVector, iter...) = foldr((v, a) -> prepend!(a, v), iter, init=a)
 
 function _prepend!(a, ::Union{HasLength,HasShape}, iter)
+    @_terminates_locally_meta
     require_one_based_indexing(a)
     n = length(iter)
     _growbeg!(a, n)
     i = 0
     for item in iter
-        @inbounds a[i += 1] = item
+        @_safeindex a[i += 1] = item
     end
     a
 end
@@ -1249,7 +1311,7 @@ function resize!(a::Vector, nl::Integer)
         _growend!(a, nl-l)
     elseif nl != l
         if nl < 0
-            throw(ArgumentError("new length must be ≥ 0"))
+            _throw_argerror("new length must be ≥ 0")
         end
         _deleteend!(a, l-nl)
     end
@@ -1329,7 +1391,7 @@ julia> pop!(Dict(1=>2))
 """
 function pop!(a::Vector)
     if isempty(a)
-        throw(ArgumentError("array must be non-empty"))
+        _throw_argerror("array must be non-empty")
     end
     item = a[end]
     _deleteend!(a, 1)
@@ -1403,24 +1465,25 @@ julia> pushfirst!([1, 2, 3, 4], 5, 6)
  4
 ```
 """
-function pushfirst!(a::Array{T,1}, item) where T
+function pushfirst!(a::Vector{T}, item) where T
     item = convert(T, item)
     _growbeg!(a, 1)
-    a[1] = item
+    @_safeindex a[1] = item
     return a
 end
 
 # specialize and optimize the single argument case
 function pushfirst!(a::Vector{Any}, @nospecialize x)
     _growbeg!(a, 1)
-    a[1] = x
+    @_safeindex a[1] = x
     return a
 end
 function pushfirst!(a::Vector{Any}, @nospecialize x...)
+    @_terminates_locally_meta
     na = length(a)
     nx = length(x)
     _growbeg!(a, nx)
-    for i = 1:nx
+    @_safeindex for i = 1:nx
         a[i] = x[i]
     end
     return a
@@ -1460,7 +1523,7 @@ julia> A
 """
 function popfirst!(a::Vector)
     if isempty(a)
-        throw(ArgumentError("array must be non-empty"))
+        _throw_argerror("array must be non-empty")
     end
     item = a[1]
     _deletebeg!(a, 1)
@@ -1600,7 +1663,7 @@ function _deleteat!(a::Vector, inds, dltd=Nowhere())
         (i,s) = y
         if !(q <= i <= n)
             if i < q
-                throw(ArgumentError("indices must be unique and sorted"))
+                _throw_argerror("indices must be unique and sorted")
             else
                 throw(BoundsError())
             end
@@ -1856,7 +1919,7 @@ for (f,_f) in ((:reverse,:_reverse), (:reverse!,:_reverse!))
         $_f(A::AbstractVector, ::Colon) = $f(A, firstindex(A), lastindex(A))
         $_f(A::AbstractVector, dim::Tuple{Integer}) = $_f(A, first(dim))
         function $_f(A::AbstractVector, dim::Integer)
-            dim == 1 || throw(ArgumentError("invalid dimension $dim ≠ 1"))
+            dim == 1 || _throw_argerror(LazyString("invalid dimension ", dim, " ≠ 1"))
             return $_f(A, :)
         end
     end