optimizer: eliminate isdefined check
#44708
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aviatesk
changed the title
sroa_mutables!isdefined check
-└── goto https://github.com/JuliaLang/julia/issues/3 if not %5
-2 ─ goto https://github.com/JuliaLang/julia/issues/4Hmm 😄 |
vtjnash
reviewed
Mar 23, 2022
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}
```
aviatesk
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Ok, let's go only with the first commit for now, and puts off the discussion on the second commit to another PR. |
aviatesk
added a commit
that referenced
this pull request
Mar 26, 2022
Follows up #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 #9 if not %7 -5 ── %9 = Core.isdefined(%2, :contents)::Bool -└─── goto #7 if not %9 +4 ┄─ %4 = (r@_2 < 0)::Any +└─── goto #9 if not %4 +5 ── goto #7 if not true 6 ── goto #8 7 ── $(Expr(:throw_undef_if_not, :r, false))::Any -8 ┄─ %13 = -r@_2::Any -9 ┄─ %14 = φ (#4 => r@_2, #8 => %13)::Any -│ %15 = Core.isdefined(%2, :contents)::Bool -└─── goto #11 if not %15 +8 ┄─ %9 = -r@_2::Any +9 ┄─ %10 = φ (#4 => r@_2, #8 => %9)::Any +└─── goto #11 if not true 10 ─ goto #12 11 ─ $(Expr(:throw_undef_if_not, :r, false))::Any -12 ┄ %19 = (x0 * %14)::Any +12 ┄ %14 = (x0 * %10)::Any └─── goto #13 -13 ─ return %19 +13 ─ return %14 ) => Any ```
aviatesk
added a commit
that referenced
this pull request
Mar 26, 2022
Follows up #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 #9 if not %7 -5 ── %9 = Core.isdefined(%2, :contents)::Bool -└─── goto #7 if not %9 +4 ┄─ %4 = (r@_2 < 0)::Any +└─── goto #9 if not %4 +5 ── goto #7 if not true 6 ── goto #8 7 ── $(Expr(:throw_undef_if_not, :r, false))::Any -8 ┄─ %13 = -r@_2::Any -9 ┄─ %14 = φ (#4 => r@_2, #8 => %13)::Any -│ %15 = Core.isdefined(%2, :contents)::Bool -└─── goto #11 if not %15 +8 ┄─ %9 = -r@_2::Any +9 ┄─ %10 = φ (#4 => r@_2, #8 => %9)::Any +└─── goto #11 if not true 10 ─ goto #12 11 ─ $(Expr(:throw_undef_if_not, :r, false))::Any -12 ┄ %19 = (x0 * %14)::Any +12 ┄ %14 = (x0 * %10)::Any └─── goto #13 -13 ─ return %19 +13 ─ return %14 ) => Any ```
aviatesk
added a commit
that referenced
this pull request
Mar 28, 2022
Follows up #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 #9 if not %7 -5 ── %9 = Core.isdefined(%2, :contents)::Bool -└─── goto #7 if not %9 +4 ┄─ %4 = (r@_2 < 0)::Any +└─── goto #9 if not %4 +5 ── goto #7 if not true 6 ── goto #8 7 ── $(Expr(:throw_undef_if_not, :r, false))::Any -8 ┄─ %13 = -r@_2::Any -9 ┄─ %14 = φ (#4 => r@_2, #8 => %13)::Any -│ %15 = Core.isdefined(%2, :contents)::Bool -└─── goto #11 if not %15 +8 ┄─ %9 = -r@_2::Any +9 ┄─ %10 = φ (#4 => r@_2, #8 => %9)::Any +└─── goto #11 if not true 10 ─ goto #12 11 ─ $(Expr(:throw_undef_if_not, :r, false))::Any -12 ┄ %19 = (x0 * %14)::Any +12 ┄ %14 = (x0 * %10)::Any └─── goto #13 -13 ─ return %19 +13 ─ return %14 ) => Any ```
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This PR is based on #44706 and consists of two separate commits.The primary change is the first commit (e205e50),
which implements additional
isdefined-elimination pass withinsroa_mutables!,and the second commit (1f7dda1) does some refactoring on top of the first change.
EDIT: now this PR only implements the first commit, and the second commit is put off to another PR.
Their commit messages follow:
optimizer: add additional
isdefined-elimination pass withinsroa_mutables!This commit implements a simple optimization within
sroa_mutables!toeliminate
isdefinedcall by checking load-forwardability of the field.This optimization may be especially useful to eliminate extra allocation
of
Core.Boxinvolved with a capturing closure, e.g.:optimizer: switch to more general data structure of
SSADefUseNow
(du::SSADefUse).usesfield can contain arbitrary "usages" to be eliminated.This structure might be helpful for implementing array SROA, for example.
Also slightly tweaks the implementation of
ccallpreserve elimination.EDIT: will not be merged in this PR.