compiler: eliminate most of unused variables in the compiler (#59202)

Found by opening the compiler folder with JETLS.

Author: aviatesk

Compiler/src/abstractinterpretation.jl

@@ -111,7 +111,7 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(fun
                                   arginfo::ArgInfo, si::StmtInfo, @nospecialize(atype),
                                   sv::AbsIntState, max_methods::Int)
     𝕃ₚ, 𝕃ᵢ = ipo_lattice(interp), typeinf_lattice(interp)
-    ⊑ₚ, ⋤ₚ, ⊔ₚ, ⊔ᵢ  = partialorder(𝕃ₚ), strictneqpartialorder(𝕃ₚ), join(𝕃ₚ), join(𝕃ᵢ)
+    ⊑ₚ, ⊔ₚ, ⊔ᵢ  = partialorder(𝕃ₚ), join(𝕃ₚ), join(𝕃ᵢ)
     argtypes = arginfo.argtypes
     if si.saw_latestworld
         add_remark!(interp, sv, "Cannot infer call, because we previously saw :latestworld")
@@ -309,7 +309,7 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(fun
                 local napplicable = length(applicable)
                 local multiple_matches = napplicable > 1
                 while inferidx[] <= napplicable
-                    (; match, edges, edge_idx) = applicable[inferidx[]]
+                    (; match) = applicable[inferidx[]]
                     inferidx[] += 1
                     local method = match.method
                     local sig = match.spec_types
@@ -343,7 +343,7 @@ function find_method_matches(interp::AbstractInterpreter, argtypes::Vector{Any},
                              max_union_splitting::Int = InferenceParams(interp).max_union_splitting,
                              max_methods::Int = InferenceParams(interp).max_methods)
     if is_union_split_eligible(typeinf_lattice(interp), argtypes, max_union_splitting)
-        return find_union_split_method_matches(interp, argtypes, atype, max_methods)
+        return find_union_split_method_matches(interp, argtypes, max_methods)
     end
     return find_simple_method_matches(interp, atype, max_methods)
 end
@@ -353,7 +353,7 @@ is_union_split_eligible(𝕃::AbstractLattice, argtypes::Vector{Any}, max_union_
     1 < unionsplitcost(𝕃, argtypes) <= max_union_splitting
 
 function find_union_split_method_matches(interp::AbstractInterpreter, argtypes::Vector{Any},
-                                         @nospecialize(atype), max_methods::Int)
+                                         max_methods::Int)
     split_argtypes = switchtupleunion(typeinf_lattice(interp), argtypes)
     infos = MethodMatchInfo[]
     applicable = MethodMatchTarget[]
@@ -994,7 +994,7 @@ function collect_const_args(argtypes::Vector{Any}, start::Int)
 end
 
 function concrete_eval_call(interp::AbstractInterpreter,
-    @nospecialize(f), result::MethodCallResult, arginfo::ArgInfo, sv::AbsIntState,
+    @nospecialize(f), result::MethodCallResult, arginfo::ArgInfo, ::AbsIntState,
     invokecall::Union{InvokeCall,Nothing}=nothing)
     args = collect_const_args(arginfo, #=start=#2)
     if invokecall !== nothing
@@ -1006,7 +1006,7 @@ function concrete_eval_call(interp::AbstractInterpreter,
     edge = result.edge::CodeInstance
     value = try
         Core._call_in_world_total(world, f, args...)
-    catch e
+    catch
         # The evaluation threw. By :consistent-cy, we're guaranteed this would have happened at runtime.
         # Howevever, at present, :consistency does not mandate the type of the exception
         concrete_result = ConcreteResult(edge, result.effects)
@@ -1368,7 +1368,6 @@ function const_prop_call(interp::AbstractInterpreter,
         inf_result.result = concrete_eval_result.rt
         inf_result.ipo_effects = concrete_eval_result.effects
     end
-    typ = inf_result.result
     return const_prop_result(inf_result)
 end
 
@@ -1466,7 +1465,7 @@ function ssa_def_slot(@nospecialize(arg), sv::InferenceState)
 end
 
 # No slots in irinterp
-ssa_def_slot(@nospecialize(arg), sv::IRInterpretationState) = nothing
+ssa_def_slot(@nospecialize(arg), ::IRInterpretationState) = nothing
 
 struct AbstractIterationResult
     cti::Vector{Any}
@@ -2262,7 +2261,7 @@ function abstract_invoke(interp::AbstractInterpreter, arginfo::ArgInfo, si::Stmt
         end
     else
         hasintersect(widenconst(types), Union{Method, CodeInstance}) && return Future(CallMeta(Any, Any, Effects(), NoCallInfo()))
-        (types, isexact, isconcrete, istype) = instanceof_tfunc(argtype_by_index(argtypes, 3), false)
+        types, isexact, _, _ = instanceof_tfunc(argtype_by_index(argtypes, 3), false)
         isexact || return Future(CallMeta(Any, Any, Effects(), NoCallInfo()))
         unwrapped = unwrap_unionall(types)
         types === Bottom && return Future(CallMeta(Bottom, Any, EFFECTS_THROWS, NoCallInfo()))
@@ -2344,7 +2343,7 @@ function abstract_finalizer(interp::AbstractInterpreter, argtypes::Vector{Any},
     if length(argtypes) == 3
         finalizer_argvec = Any[argtypes[2], argtypes[3]]
         call = abstract_call(interp, ArgInfo(nothing, finalizer_argvec), StmtInfo(false, false), sv, #=max_methods=#1)::Future
-        return Future{CallMeta}(call, interp, sv) do call, interp, sv
+        return Future{CallMeta}(call, interp, sv) do call, _, _
             return CallMeta(Nothing, Any, Effects(), FinalizerInfo(call.info, call.effects))
         end
     end
@@ -2369,7 +2368,7 @@ function abstract_throw(interp::AbstractInterpreter, argtypes::Vector{Any}, ::Ab
     return Future(CallMeta(Union{}, exct, EFFECTS_THROWS, NoCallInfo()))
 end
 
-function abstract_throw_methoderror(interp::AbstractInterpreter, argtypes::Vector{Any}, ::AbsIntState)
+function abstract_throw_methoderror(::AbstractInterpreter, argtypes::Vector{Any}, ::AbsIntState)
     exct = if length(argtypes) == 1
         ArgumentError
     elseif !isvarargtype(argtypes[2])
@@ -2579,7 +2578,7 @@ end
 function abstract_eval_replaceglobal!(interp::AbstractInterpreter, sv::AbsIntState, saw_latestworld::Bool, argtypes::Vector{Any})
     if !isvarargtype(argtypes[end])
         if length(argtypes) in (5, 6, 7)
-            (M, s, x, v) = argtypes[2], argtypes[3], argtypes[4], argtypes[5]
+            (M, s, v) = argtypes[2], argtypes[3], argtypes[5]
             T = nothing
             if isa(M, Const) && isa(s, Const)
                 M, s = M.val, s.val
@@ -2855,7 +2854,6 @@ function abstract_call_opaque_closure(interp::AbstractInterpreter,
 end
 
 function most_general_argtypes(closure::PartialOpaque)
-    ret = Any[]
     cc = widenconst(closure)
     argt = (unwrap_unionall(cc)::DataType).parameters[1]
     if !isa(argt, DataType) || argt.name !== typename(Tuple)
@@ -3054,7 +3052,7 @@ function abstract_call(interp::AbstractInterpreter, arginfo::ArgInfo, sstate::St
     end
     si = StmtInfo(!unused, sstate.saw_latestworld)
     call = abstract_call(interp, arginfo, si, sv)::Future
-    Future{Any}(call, interp, sv) do call, interp, sv
+    Future{Any}(call, interp, sv) do call, _, sv
         # this only is needed for the side-effect, sequenced before any task tries to consume the return value,
         # which this will do even without returning this Future
         sv.stmt_info[sv.currpc] = call.info
@@ -3072,7 +3070,7 @@ function abstract_eval_call(interp::AbstractInterpreter, e::Expr, sstate::Statem
     end
     arginfo = ArgInfo(ea, argtypes)
     call = abstract_call(interp, arginfo, sstate, sv)::Future
-    return Future{RTEffects}(call, interp, sv) do call, interp, sv
+    return Future{RTEffects}(call, interp, sv) do call, _, _
         (; rt, exct, effects, refinements) = call
         return RTEffects(rt, exct, effects, refinements)
     end
@@ -3081,7 +3079,7 @@ end
 function abstract_eval_new(interp::AbstractInterpreter, e::Expr, sstate::StatementState,
                            sv::AbsIntState)
     𝕃ᵢ = typeinf_lattice(interp)
-    rt, isexact = instanceof_tfunc(abstract_eval_value(interp, e.args[1], sstate, sv), true)
+    rt, _... = instanceof_tfunc(abstract_eval_value(interp, e.args[1], sstate, sv), true)
     ut = unwrap_unionall(rt)
     exct = Union{ErrorException,TypeError}
     if isa(ut, DataType) && !isabstracttype(ut)
@@ -3234,7 +3232,7 @@ function abstract_eval_new_opaque_closure(interp::AbstractInterpreter, e::Expr,
                 pushfirst!(argtypes, rt.env)
                 callinfo = abstract_call_opaque_closure(interp, rt,
                     ArgInfo(nothing, argtypes), StmtInfo(true, false), sv, #=check=#false)::Future
-                Future{Any}(callinfo, interp, sv) do callinfo, interp, sv
+                Future{Any}(callinfo, interp, sv) do callinfo, _, sv
                     sv.stmt_info[sv.currpc] = OpaqueClosureCreateInfo(callinfo)
                     nothing
                 end
@@ -3311,7 +3309,7 @@ function abstract_eval_isdefinedglobal(interp::AbstractInterpreter, mod::Module,
         end
     end
 
-    (valid_worlds, rte) = abstract_load_all_consistent_leaf_partitions(interp, gr, sv.world)
+    (_, rte) = abstract_load_all_consistent_leaf_partitions(interp, gr, sv.world)
     if rte.exct == Union{}
         rt = Const(true)
     elseif rte.rt === Union{} && rte.exct === UndefVarError
@@ -3607,13 +3605,10 @@ world_range(compact::IncrementalCompact) = world_range(compact.ir)
 
 function abstract_eval_globalref_type(g::GlobalRef, src::Union{CodeInfo, IRCode, IncrementalCompact})
     worlds = world_range(src)
-    partition = lookup_binding_partition(min_world(worlds), g)
-
     (valid_worlds, rte) = abstract_load_all_consistent_leaf_partitions(nothing, g, WorldWithRange(min_world(worlds), worlds))
     if min_world(valid_worlds) > min_world(worlds) || max_world(valid_worlds) < max_world(worlds)
         return Any
     end
-
     return rte.rt
 end
 
@@ -3730,7 +3725,7 @@ scan_leaf_partitions(query::F, interp::AbstractInterpreter, g::GlobalRef, wwr::W
     scan_specified_partitions(query, walk_binding_partition, interp, g, wwr)
 
 function scan_partitions(query::F, interp::AbstractInterpreter, g::GlobalRef, wwr::WorldWithRange) where F
-    walk_binding_partition = function (b::Core.Binding, partition::Core.BindingPartition, world::UInt)
+    walk_binding_partition = function (b::Core.Binding, partition::Core.BindingPartition, ::UInt)
         Pair{WorldRange, Pair{Core.Binding, Core.BindingPartition}}(
             WorldRange(partition.min_world, partition.max_world), b=>partition)
     end
@@ -4489,7 +4484,6 @@ function typeinf(interp::AbstractInterpreter, frame::InferenceState)
     nextstates = CurrentState[]
     takenext = frame.frameid
     minwarn = warnlength
-    takeprev = 0
     while takenext >= frame.frameid
         callee = takenext == 0 ? frame : callstack[takenext]::InferenceState
         if !isempty(callstack)

Compiler/src/bootstrap.jl

@@ -48,7 +48,6 @@ function bootstrap!()
             end
         end
         starttime = time()
-        methods = Any[]
         world = get_world_counter()
         for f in fs
             if isa(f, DataType) && f.name === typename(Tuple)

Compiler/src/inferenceresult.jl

@@ -1,6 +1,6 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
-function matching_cache_argtypes(𝕃::AbstractLattice, mi::MethodInstance)
+function matching_cache_argtypes(::AbstractLattice, mi::MethodInstance)
     (; def, specTypes) = mi
     return most_general_argtypes(isa(def, Method) ? def : nothing, specTypes)
 end
@@ -16,7 +16,7 @@ struct WidenedArgtypes
     argtypes::Vector{Any}
 end
 
-function matching_cache_argtypes(𝕃::AbstractLattice, mi::MethodInstance,
+function matching_cache_argtypes(𝕃::AbstractLattice, ::MethodInstance,
                                  simple_argtypes::Union{SimpleArgtypes, WidenedArgtypes},
                                  cache_argtypes::Vector{Any})
     (; argtypes) = simple_argtypes

Compiler/src/inferencestate.jl

@@ -340,12 +340,12 @@ mutable struct InferenceState
         ssavalue_uses = find_ssavalue_uses(code, nssavalues)
         nstmts = length(code)
         edges = []
-        stmt_info = CallInfo[ NoCallInfo() for i = 1:nstmts ]
+        stmt_info = CallInfo[ NoCallInfo() for _ = 1:nstmts ]
 
         nslots = length(src.slotflags)
         slottypes = Vector{Any}(undef, nslots)
-        bb_saw_latestworld = Bool[false for i = 1:length(cfg.blocks)]
-        bb_vartables = Union{Nothing,VarTable}[ nothing for i = 1:length(cfg.blocks) ]
+        bb_saw_latestworld = Bool[false for _ = 1:length(cfg.blocks)]
+        bb_vartables = Union{Nothing,VarTable}[ nothing for _ = 1:length(cfg.blocks) ]
         bb_vartable1 = bb_vartables[1] = VarTable(undef, nslots)
         argtypes = result.argtypes
 
@@ -360,7 +360,7 @@ mutable struct InferenceState
             slottypes[i] = argtyp
             bb_vartable1[i] = VarState(argtyp, i > nargtypes)
         end
-        src.ssavaluetypes = ssavaluetypes = Any[ NOT_FOUND for i = 1:nssavalues ]
+        src.ssavaluetypes = ssavaluetypes = Any[ NOT_FOUND for _ = 1:nssavalues ]
         ssaflags = copy(src.ssaflags)
 
         unreachable = BitSet()
@@ -549,7 +549,7 @@ function (::ComputeTryCatch{Handler})(code::Vector{Any}, bbs::Union{Vector{Basic
                         l += 1
                     end
                     cur_hand = cur_stacks[1]
-                    for i = 1:l
+                    for _ = 1:l
                         cur_hand = handler_at[get_enter_idx(handlers[cur_hand])][1]
                     end
                     cur_stacks = (cur_hand, cur_stacks[2])

Compiler/src/optimize.jl

@@ -143,7 +143,7 @@ function src_inlining_policy(interp::AbstractInterpreter, mi::MethodInstance,
     return src_inlining_policy(interp, src, info, stmt_flag)
 end
 
-function src_inlining_policy(interp::AbstractInterpreter,
+function src_inlining_policy(::AbstractInterpreter,
     @nospecialize(src), @nospecialize(info::CallInfo), stmt_flag::UInt32)
     isa(src, OptimizationState) && (src = src.src)
     if isa(src, MaybeCompressed)
@@ -238,17 +238,17 @@ function OptimizationState(mi::MethodInstance, src::CodeInfo, interp::AbstractIn
     # prepare src for running optimization passes if it isn't already
     nssavalues = src.ssavaluetypes
     if nssavalues isa Int
-        src.ssavaluetypes = Any[ Any for i = 1:nssavalues ]
+        src.ssavaluetypes = Any[ Any for _ = 1:nssavalues ]
     else
         nssavalues = length(src.ssavaluetypes::Vector{Any})
     end
     sptypes = sptypes_from_meth_instance(mi)
     nslots = length(src.slotflags)
     slottypes = src.slottypes
     if slottypes === nothing
-        slottypes = Any[ Any for i = 1:nslots ]
+        slottypes = Any[ Any for _ = 1:nslots ]
     end
-    stmt_info = CallInfo[ NoCallInfo() for i = 1:nssavalues ]
+    stmt_info = CallInfo[ NoCallInfo() for _ = 1:nssavalues ]
     # cache some useful state computations
     def = mi.def
     mod = isa(def, Method) ? def.module : def
@@ -258,7 +258,7 @@ function OptimizationState(mi::MethodInstance, src::CodeInfo, interp::AbstractIn
     cfg = compute_basic_blocks(src.code)
     unreachable = BitSet()
     bb_vartables = Union{VarTable,Nothing}[]
-    for block = 1:length(cfg.blocks)
+    for _ = 1:length(cfg.blocks)
         push!(bb_vartables, VarState[
             VarState(slottypes[slot], src.slotflags[slot] & SLOT_USEDUNDEF != 0)
             for slot = 1:nslots
@@ -554,7 +554,7 @@ abstract_eval_ssavalue(s::SSAValue, src::Union{IRCode,IncrementalCompact}) = typ
 
 Called at the end of optimization to store the resulting IR back into the OptimizationState.
 """
-function finishopt!(interp::AbstractInterpreter, opt::OptimizationState, ir::IRCode)
+function finishopt!(::AbstractInterpreter, opt::OptimizationState, ir::IRCode)
     opt.optresult = OptimizationResult(ir, ccall(:jl_ir_flag_inlining, UInt8, (Any,), opt.src), false)
     return nothing
 end
@@ -1013,7 +1013,7 @@ function ipo_dataflow_analysis!(interp::AbstractInterpreter, opt::OptimizationSt
             check_inconsistentcy!(sv, scanner)
         else
             # No longer any dataflow concerns, just scan the flags
-            scan!(scanner, false) do inst::Instruction, lstmt::Int, bb::Int
+            scan!(scanner, false) do inst::Instruction, ::Int, ::Int
                 scan_non_dataflow_flags!(inst, sv)
                 # bail out early if there are no possibilities to refine the effects
                 if !any_refinable(sv)
@@ -1337,7 +1337,6 @@ end
 
 function slot2reg(ir::IRCode, ci::CodeInfo, sv::OptimizationState)
     # need `ci` for the slot metadata, IR for the code
-    svdef = sv.linfo.def
     @zone "CC: DOMTREE_1" domtree = construct_domtree(ir)
     defuse_insts = scan_slot_def_use(Int(ci.nargs), ci, ir.stmts.stmt)
     𝕃ₒ = optimizer_lattice(sv.inlining.interp)

Compiler/src/stmtinfo.jl

@@ -135,7 +135,7 @@ function add_one_edge!(edges::Vector{Any}, edge::CodeInstance)
     push!(edges, edge)
     nothing
 end
-nsplit_impl(info::MethodMatchInfo) = 1
+nsplit_impl(::MethodMatchInfo) = 1
 getsplit_impl(info::MethodMatchInfo, idx::Int) = (@assert idx == 1; info.results)
 getresult_impl(::MethodMatchInfo, ::Int) = nothing
 
@@ -279,7 +279,7 @@ struct InvokeCICallInfo <: CallInfo
 end
 add_edges_impl(edges::Vector{Any}, info::InvokeCICallInfo) =
     add_inlining_edge!(edges, info.edge)
-nsplit_impl(info::InvokeCICallInfo) = 0
+nsplit_impl(::InvokeCICallInfo) = 0
 
 """
     info::InvokeCallInfo
@@ -392,7 +392,7 @@ function add_inlining_edge!(edges::Vector{Any}, edge::CodeInstance)
     nothing
 end
 
-nsplit_impl(info::InvokeCallInfo) = 1
+nsplit_impl(::InvokeCallInfo) = 1
 getsplit_impl(info::InvokeCallInfo, idx::Int) = (@assert idx == 1; MethodLookupResult(Core.MethodMatch[info.match],
     WorldRange(typemin(UInt), typemax(UInt)), false))
 getresult_impl(info::InvokeCallInfo, idx::Int) = (@assert idx == 1; info.result)