Fork | CITATION.cff changed on release-1.7 #3
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abelsiqueira
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This commit implements a simple optimization within `sroa_mutables!` to
eliminate `isdefined` call by checking load-forwardability of the field.
This optimization may be especially useful to eliminate extra allocation
of `Core.Box` involved with a capturing closure, e.g.:
```julia
julia> callit(f, args...) = f(args...);
julia> function isdefined_elim()
local arr::Vector{Any}
callit() do
arr = Any[]
end
return arr
end;
julia> code_typed(isdefined_elim)
```
```diff
diff --git a/_master.jl b/_pr.jl
index 3aa40ba20e5..11eccf65f32 100644
--- a/_master.jl
+++ b/_pr.jl
@@ -1,15 +1,8 @@
1-element Vector{Any}:
CodeInfo(
-1 ─ %1 = Core.Box::Type{Core.Box}
-│ %2 = %new(%1)::Core.Box
-│ %3 = $(Expr(:foreigncall, :(:jl_alloc_array_1d), Vector{Any}, svec(Any, Int64), 0, :(:ccall), Vector{Any}, 0, 0))::Vector{Any}
-│ Core.setfield!(%2, :contents, %3)::Vector{Any}
-│ %5 = Core.isdefined(%2, :contents)::Bool
-└── goto #3 if not %5
-2 ─ goto #4
-3 ─ $(Expr(:throw_undef_if_not, :arr, false))::Any
-4 ┄ %9 = Core.getfield(%2, :contents)::Any
-│ Core.typeassert(%9, Vector{Any})::Vector{Any}
-│ %11 = π (%9, Vector{Any})
-└── return %11
+1 ─ %1 = $(Expr(:foreigncall, :(:jl_alloc_array_1d), Vector{Any}, svec(Any, Int64), 0, :(:ccall), Vector{Any}, 0, 0))::Vector{Any}
+└── goto #3 if not true
+2 ─ goto #4
+3 ─ $(Expr(:throw_undef_if_not, :arr, false))::Any
+4 ┄ return %1
) => Vector{Any}
```
abelsiqueira
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In JuliaLang#44635, we observe that occasionally a call to `view(::SubArray, ::Colon, ...)` dispatches to the wrong function. The post-inlining IR is in relevant part: ``` │ │ %8 = (isa)(I, Tuple{Colon, UnitRange{Int64}, SubArray{Int64, 2, UnitRange{Int64}, Tuple{Matrix{Int64}}, false}})::Bool └───│ goto #3 if not %8 2 ──│ %10 = π (I, Tuple{Colon, UnitRange{Int64}, SubArray{Int64, 2, UnitRange{Int64}, Tuple{Matrix{Int64}}, false}}) │ │ @ indices.jl:324 within `to_indices` @ multidimensional.jl:859 │ │┌ @ multidimensional.jl:864 within `uncolon` │ ││┌ @ indices.jl:351 within `Slice` @ indices.jl:351 │ │││ %11 = %new(Base.Slice{Base.OneTo{Int64}}, %7)::Base.Slice{Base.OneTo{Int64}} │ │└└ │ │┌ @ essentials.jl:251 within `tail` │ ││ %12 = Core.getfield(%10, 2)::UnitRange{Int64} │ ││ %13 = Core.getfield(%10, 3)::SubArray{Int64, 2, UnitRange{Int64}, Tuple{Matrix{Int64}}, false} │ │└ │ │ @ indices.jl:324 within `to_indices` └───│ goto JuliaLang#5 │ @ indices.jl:324 within `to_indices` @ indices.jl:333 │┌ @ tuple.jl:29 within `getindex` 3 ──││ %15 = Base.getfield(I, 1, true)::Function │ │└ │ │ invoke Base.to_index(A::SubArray{Int64, 3, Array{Int64, 3}, Tuple{Vector{Int64}, Base.Slice{Base.OneTo{Int64}}, UnitRange{Int64}}, false}, %15::Function)::Union{} ``` Here we expect the `isa` at `%8` to always be [1]. However, we seemingly observe the result that the branch is not taken and we instead end up in the fallback `to_index`, which (correctly) complains that the colon should have been dereferenced to an index. After some investigation of the relevant rr trace, what turns out to happen here is that the va tuple we compute in codegen gets garbage collected before the call to `emit_isa`, causing a use-after-free read, which happens to make `emit_isa` think that the isa condition is impossible, causing it to fold the branch away. The fix is to simply add the relevant GC root. It's a bit unfortunate that this wasn't caught by the GC verifier. It would have in principle been capable of doing so, but it is currently disabled for C++ sources. It would be worth revisiting this in the future to see if it can't be made to work. Fixes JuliaLang#44635. [1] The specialization heuristics decided to widen `Colon` to `Function`, which doesn't make much sense here, but regardless, it shouldn't crash.
abelsiqueira
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Follows up JuliaLang#44708 -- in that PR I missed the most obvious optimization opportunity, i.e. we can safely eliminate `isdefined` checks when all fields are defined at allocation site. This change allows us to eliminate capturing closure constructions when the body and callsite of capture closure is available within a optimized frame, e.g.: ```julia function abmult(r::Int, x0) if r < 0 r = -r end f = x -> x * r return @inline f(x0) end ``` ```diff diff --git a/_master.jl b/_pr.jl index ea06d865b75..c38f221090f 100644 --- a/_master.jl +++ b/_pr.jl @@ -1,24 +1,19 @@ julia> @code_typed abmult(-3, 3) CodeInfo( -1 ── %1 = Core.Box::Type{Core.Box} -│ %2 = %new(%1, r@_2)::Core.Box -│ %3 = Core.isdefined(%2, :contents)::Bool -└─── goto #3 if not %3 +1 ── goto #3 if not true 2 ── goto #4 3 ── $(Expr(:throw_undef_if_not, :r, false))::Any -4 ┄─ %7 = (r@_2 < 0)::Any -└─── goto JuliaLang#9 if not %7 -5 ── %9 = Core.isdefined(%2, :contents)::Bool -└─── goto JuliaLang#7 if not %9 +4 ┄─ %4 = (r@_2 < 0)::Any +└─── goto JuliaLang#9 if not %4 +5 ── goto JuliaLang#7 if not true 6 ── goto JuliaLang#8 7 ── $(Expr(:throw_undef_if_not, :r, false))::Any -8 ┄─ %13 = -r@_2::Any -9 ┄─ %14 = φ (#4 => r@_2, JuliaLang#8 => %13)::Any -│ %15 = Core.isdefined(%2, :contents)::Bool -└─── goto JuliaLang#11 if not %15 +8 ┄─ %9 = -r@_2::Any +9 ┄─ %10 = φ (#4 => r@_2, JuliaLang#8 => %9)::Any +└─── goto JuliaLang#11 if not true 10 ─ goto JuliaLang#12 11 ─ $(Expr(:throw_undef_if_not, :r, false))::Any -12 ┄ %19 = (x0 * %14)::Any +12 ┄ %14 = (x0 * %10)::Any └─── goto JuliaLang#13 -13 ─ return %19 +13 ─ return %14 ) => Any ```
abelsiqueira
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Currently the optimizer handles abstract callsite only when there is a single dispatch candidate (in most cases), and so inlining and static-dispatch are prohibited when the callsite is union-split (in other word, union-split happens only when all the dispatch candidates are concrete). However, there are certain patterns of code (most notably our Julia-level compiler code) that inherently need to deal with abstract callsite. The following example is taken from `Core.Compiler` utility: ```julia julia> @inline isType(@nospecialize t) = isa(t, DataType) && t.name === Type.body.name isType (generic function with 1 method) julia> code_typed((Any,)) do x # abstract, but no union-split, successful inlining isType(x) end |> only CodeInfo( 1 ─ %1 = (x isa Main.DataType)::Bool └── goto #3 if not %1 2 ─ %3 = π (x, DataType) │ %4 = Base.getfield(%3, :name)::Core.TypeName │ %5 = Base.getfield(Type{T}, :name)::Core.TypeName │ %6 = (%4 === %5)::Bool └── goto #4 3 ─ goto #4 4 ┄ %9 = φ (#2 => %6, #3 => false)::Bool └── return %9 ) => Bool julia> code_typed((Union{Type,Nothing},)) do x # abstract, union-split, unsuccessful inlining isType(x) end |> only CodeInfo( 1 ─ %1 = (isa)(x, Nothing)::Bool └── goto #3 if not %1 2 ─ goto #4 3 ─ %4 = Main.isType(x)::Bool └── goto #4 4 ┄ %6 = φ (#2 => false, #3 => %4)::Bool └── return %6 ) => Bool ``` (note that this is a limitation of the inlining algorithm, and so any user-provided hints like callsite inlining annotation doesn't help here) This commit enables inlining and static dispatch for abstract union-split callsite. The core idea here is that we can simulate our dispatch semantics by generating `isa` checks in order of the specialities of dispatch candidates: ```julia julia> code_typed((Union{Type,Nothing},)) do x # union-split, unsuccessful inlining isType(x) end |> only CodeInfo( 1 ─ %1 = (isa)(x, Nothing)::Bool └── goto #3 if not %1 2 ─ goto JuliaLang#9 3 ─ %4 = (isa)(x, Type)::Bool └── goto JuliaLang#8 if not %4 4 ─ %6 = π (x, Type) │ %7 = (%6 isa Main.DataType)::Bool └── goto JuliaLang#6 if not %7 5 ─ %9 = π (%6, DataType) │ %10 = Base.getfield(%9, :name)::Core.TypeName │ %11 = Base.getfield(Type{T}, :name)::Core.TypeName │ %12 = (%10 === %11)::Bool └── goto JuliaLang#7 6 ─ goto JuliaLang#7 7 ┄ %15 = φ (JuliaLang#5 => %12, JuliaLang#6 => false)::Bool └── goto JuliaLang#9 8 ─ Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{} └── unreachable 9 ┄ %19 = φ (#2 => false, JuliaLang#7 => %15)::Bool └── return %19 ) => Bool ``` Inlining/static-dispatch of abstract union-split callsite will improve the performance in such situations (and so this commit will improve the latency of our JIT compilation). Especially, this commit helps us avoid excessive specializations of `Core.Compiler` code by statically-resolving `@nospecialize`d callsites, and as the result, the # of precompiled statements is now reduced from `2005` ([`master`](f782430)) to `1912` (this commit). And also, as a side effect, the implementation of our inlining algorithm gets much simplified now since we no longer need the previous special handlings for abstract callsites. One possible drawback would be increased code size. This change seems to certainly increase the size of sysimage, but I think these numbers are in an acceptable range: > [`master`](f782430) ``` ❯ du -shk usr/lib/julia/* 17604 usr/lib/julia/corecompiler.ji 194072 usr/lib/julia/sys-o.a 169424 usr/lib/julia/sys.dylib 23784 usr/lib/julia/sys.dylib.dSYM 103772 usr/lib/julia/sys.ji ``` > this commit ``` ❯ du -shk usr/lib/julia/* 17512 usr/lib/julia/corecompiler.ji 195588 usr/lib/julia/sys-o.a 170908 usr/lib/julia/sys.dylib 23776 usr/lib/julia/sys.dylib.dSYM 105360 usr/lib/julia/sys.ji ```
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This PR is to cffbots/julia release-1.7 from a fork with changes to CFF
Notice that
release-1.7here has cherry-pickedcffconvert.yml.