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More aggressive allocation elimination. #16021

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Apr 27, 2016
+96 −35
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More aggressive allocation elimination. #16021

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131 changes: 96 additions & 35 deletions base/inference.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -2430,7 +2430,7 @@ function inlineable(f::ANY, ft::ANY, e::Expr, atypes::Vector{Any}, sv::Inference
# argument tuple is not used as a whole, so convert function body
# to one accepting the exact number of arguments we have.
newnames = unique_names(ast,valen)
replace_getfield!(ast, body, vaname, newnames, sv, 1)
replace_getfield!(ast, body, vaname, newnames, sv)
na = na-1+valen
# if the argument name is also used as a local variable,
Expand Down Expand Up @@ -3039,7 +3039,7 @@ function remove_redundant_temp_vars(linfo, sa, T)
gensym_types = linfo.gensymtypes
bexpr = Expr(:block); bexpr.args = linfo.code
for (v,init) in sa
if (isa(init, Slot) && !is_var_assigned(linfo, init))
if (isa(init, Slot) && !is_var_assigned(linfo, init::Slot))
# this transformation is not valid for vars used before def.
# we need to preserve the point of assignment to know where to
# throw errors (issue #4645).
Expand Down Expand Up @@ -3092,8 +3092,9 @@ symequal(x::GenSym, y::GenSym) = is(x.id,y.id)
symequal(x::Slot , y::Slot) = is(x.id,y.id)
symequal(x::ANY , y::ANY) = is(x,y)

function occurs_outside_getfield(e::ANY, sym::ANY, sv::InferenceState, field_count, field_names)
if e===sym || (isa(e,Slot) && isa(sym,Slot) && e.id == sym.id)
function occurs_outside_getfield(linfo::LambdaInfo, e::ANY, sym::ANY,
sv::InferenceState, field_count, field_names)
if e===sym || (isa(e,Slot) && isa(sym,Slot) && (e::Slot).id == (sym::Slot).id)
return true
end
if isa(e,Expr)
Expand All @@ -3109,10 +3110,21 @@ function occurs_outside_getfield(e::ANY, sym::ANY, sv::InferenceState, field_cou
return true
end
if is(e.head,:(=))
return occurs_outside_getfield(e.args[2], sym, sv, field_count, field_names)
return occurs_outside_getfield(linfo, e.args[2], sym, sv,
field_count, field_names)
else
if (e.head === :block && isa(sym, Slot) &&
linfo.slotflags[(sym::Slot).id] & 32 == 0)
# This is the used-undef flag according to Jeff
ignore_void = true
else
ignore_void = false
end
for a in e.args
if occurs_outside_getfield(a, sym, sv, field_count, field_names)
if ignore_void && isa(a, Slot) && (a::Slot).id == (sym::Slot).id
continue
end
if occurs_outside_getfield(linfo, a, sym, sv, field_count, field_names)
return true
end
end
Expand Down Expand Up @@ -3149,7 +3161,7 @@ function _getfield_elim_pass!(e::Expr, sv)
e1 = e.args[2]
j = e.args[3]
if isa(e1,Expr)
alloc = is_immutable_allocation(e1, sv)
alloc = is_allocation(e1, sv)
if !is(alloc, false)
flen, fnames = alloc
if isa(j,QuoteNode)
Expand Down Expand Up @@ -3184,16 +3196,16 @@ end

_getfield_elim_pass!(e::ANY, sv) = e

# check if e is a successful allocation of an immutable struct
# check if e is a successful allocation of an struct
# if it is, returns (n,f) such that it is always valid to call
# getfield(..., 1 <= x <= n) or getfield(..., x in f) on the result
function is_immutable_allocation(e :: ANY, sv::InferenceState)
function is_allocation(e :: ANY, sv::InferenceState)
isa(e, Expr) || return false
if is_known_call(e, tuple, sv)
return (length(e.args)-1,())
elseif e.head === :new
typ = widenconst(exprtype(e, sv))
if isleaftype(typ) && !typ.mutable
if isleaftype(typ)
@assert(isa(typ,DataType))
nf = length(e.args)-1
names = fieldnames(typ)
Expand All @@ -3210,7 +3222,7 @@ function is_immutable_allocation(e :: ANY, sv::InferenceState)
false
end

# eliminate allocation of unnecessary immutables
# eliminate allocation of unnecessary objects
# that are only used as arguments to safe getfield calls
function alloc_elim_pass!(linfo::LambdaInfo, sv::InferenceState)
body = linfo.code
Expand All @@ -3221,49 +3233,98 @@ function alloc_elim_pass!(linfo::LambdaInfo, sv::InferenceState)
i = 1
while i < length(body)
e = body[i]
if !(isa(e,Expr) && is(e.head,:(=)) && (isa(e.args[1], GenSym) ||
(isa(e.args[1],Slot) && haskey(vs, e.args[1].id))))
if !isa(e, Expr)
i += 1
continue
end
var = e.args[1]
rhs = e.args[2]
alloc = is_immutable_allocation(rhs, sv)
if !is(alloc,false)
e = e::Expr
if e.head === :(=) && (isa(e.args[1], GenSym) ||
(isa(e.args[1],Slot) && haskey(vs, e.args[1].id)))
var = e.args[1]
rhs = e.args[2]
else
var = nothing
rhs = e
end
alloc = is_allocation(rhs, sv)
if alloc !== false
nv, field_names = alloc
tup = rhs.args
if occurs_outside_getfield(bexpr, var, sv, nv, field_names)
# This makes sure the value doesn't escape so we can elide
# allocation of mutable types too
if (var !== nothing &&
occurs_outside_getfield(linfo, bexpr, var, sv, nv, field_names))
i += 1
continue
end

deleteat!(body, i) # remove tuple allocation
# convert tuple allocation to a series of local var assignments
vals = cell(nv)
n_ins = 0
for j=1:nv
tupelt = tup[j+1]
if isa(tupelt,Number) || isa(tupelt,AbstractString) || isa(tupelt,QuoteNode)
vals[j] = tupelt
else
elty = exprtype(tupelt,sv)
tmpv = newvar!(sv, elty)
tmp = Expr(:(=), tmpv, tupelt)
insert!(body, i+n_ins, tmp)
vals[j] = tmpv
n_ins += 1
if var === nothing
for j=1:nv
tupelt = tup[j+1]
if !(isa(tupelt,Number) || isa(tupelt,AbstractString) ||
isa(tupelt,QuoteNode) || isa(tupelt, GenSym))
insert!(body, i+n_ins, tupelt)
n_ins += 1
end
end
else
vals = cell(nv)
for j=1:nv
tupelt = tup[j+1]
if (isa(tupelt,Number) || isa(tupelt,AbstractString) ||
isa(tupelt,QuoteNode) || isa(tupelt, GenSym))
vals[j] = tupelt
else
elty = exprtype(tupelt,sv)
tmpv = newvar!(sv, elty)
tmp = Expr(:(=), tmpv, tupelt)
insert!(body, i+n_ins, tmp)
vals[j] = tmpv
n_ins += 1
end
end
replace_getfield!(linfo, bexpr, var, vals, field_names, sv)
if isa(var, Slot) && linfo.slotflags[(var::Slot).id] & 32 == 0
# occurs_outside_getfield might have allowed
# void use of the slot, we need to delete them too
i -= delete_void_use!(body, var::Slot, i)
end
end
# Do not increment counter and do the optimization recursively
# on the allocation of fields too.
# This line can probably be added back for linear IR
# i += n_ins
else
i += 1
end
end
end

# Return the number of expressions deleted before `i0`
function delete_void_use!(body, var::Slot, i0)
narg = length(body)
i = 1
ndel = 0
while i <= narg
a = body[i]
if isa(a, Slot) && (a::Slot).id == var.id
deleteat!(body, i)
if i + ndel < i0
ndel += 1
end
i += n_ins
replace_getfield!(linfo, bexpr, var, vals, field_names, sv, i)
narg -= 1
else
i += 1
end
end
ndel
end

function replace_getfield!(linfo::LambdaInfo, e::Expr, tupname, vals, field_names, sv, i0)
for i = i0:length(e.args)
function replace_getfield!(linfo::LambdaInfo, e::Expr, tupname, vals, field_names, sv)
for i = 1:length(e.args)
a = e.args[i]
if isa(a,Expr) && is_known_call(a, getfield, sv) &&
symequal(a.args[2],tupname)
Expand Down Expand Up @@ -3292,7 +3353,7 @@ function replace_getfield!(linfo::LambdaInfo, e::Expr, tupname, vals, field_name
end
e.args[i] = val
elseif isa(a, Expr)
replace_getfield!(linfo, a::Expr, tupname, vals, field_names, sv, 1)
replace_getfield!(linfo, a::Expr, tupname, vals, field_names, sv)
end
end
end
Expand Down