Track invalidations during deserialization

These were printed to the console but not otherwise stored.
Storing them allows one to give them more emphasis and perform
analysis. With JuliaLang/julia#41913,
it becomes possible to attribute them to specific method
definitions or deletions. (Of course there might be multiple
reasons, but we need to identify at least one in order to make
progress.)

Author: timholy

src/invalidations.jl

@@ -74,6 +74,10 @@ mutable struct InstanceNode
     end
 end
 
+Core.MethodInstance(node::InstanceNode) = node.mi
+Base.convert(::Type{MethodInstance}, node::InstanceNode) = node.mi
+AbstractTrees.children(node::InstanceNode) = node.children
+
 function getroot(node::InstanceNode)
     while isdefined(node, :parent)
         node = node.parent
@@ -133,7 +137,7 @@ end
 struct MethodInvalidations
     method::Method
     reason::Symbol   # :inserting or :deleting
-    mt_backedges::Vector{Pair{Any,InstanceNode}}   # sig=>root
+    mt_backedges::Vector{Pair{Any,Union{InstanceNode,MethodInstance}}}   # sig=>root
     backedges::Vector{InstanceNode}
     mt_cache::Vector{MethodInstance}
     mt_disable::Vector{MethodInstance}
@@ -145,7 +149,8 @@ end
 
 Base.isempty(methinvs::MethodInvalidations) = isempty(methinvs.mt_backedges) && isempty(methinvs.backedges)  # ignore mt_cache
 
-countchildren(sigtree::Pair{<:Any,InstanceNode}) = countchildren(sigtree.second)
+countchildren(sigtree::Pair{<:Any,Union{InstanceNode,MethodInstance}}) = countchildren(sigtree.second)
+countchildren(::MethodInstance) = 1
 
 function countchildren(methinvs::MethodInvalidations)
     n = 0
@@ -179,7 +184,15 @@ function Base.show(io::IO, methinvs::MethodInvalidations)
             sig = nothing
             if isa(root, Pair)
                 print(io, "signature ")
-                printstyled(io, root.first, color = :light_cyan)
+                sig = root.first
+                if isa(sig, MethodInstance)
+                    # "insert_backedges_callee"/"insert_backedges" (delayed) invalidations
+                    printstyled(io, which(sig.specTypes), color = :light_cyan)
+                    print(io, " (formerly ", sig.def, ')')
+                else
+                    # `sig` (immediate) invalidations
+                    printstyled(io, sig, color = :light_cyan)
+                end
                 print(io, " triggered ")
                 sig = root.first
                 root = root.second
@@ -189,7 +202,7 @@ function Base.show(io::IO, methinvs::MethodInvalidations)
                 print(io, " with ")
                 sig = root.mi.def.sig
             end
-            printstyled(io, root.mi, color = :light_yellow)
+            printstyled(io, convert(MethodInstance, root), color = :light_yellow)
             print(io, " (", countchildren(root), " children)")
             if iscompact
                 i < n && print(io, ", ")
@@ -275,7 +288,29 @@ function invalidation_trees(list; exclude_corecompiler::Bool=true)
         return reason
     end
 
+    function handle_insert_backedges(list, i, callee)
+        ncovered = 0
+        while length(list) >= i+2 && list[i+2] == "insert_backedges_callee"
+            if isa(callee, Type)
+                newcallee = list[i+1]
+                if isa(newcallee, MethodInstance)
+                    callee = newcallee
+                end
+            end
+            i += 2
+        end
+        while length(list) >= i+2 && list[i+2] == "insert_backedges"
+            caller = list[i+=1]
+            i += 1
+            push!(delayed, callee => caller)
+            ncovered += 1
+        end
+        @assert ncovered > 0
+        return i
+    end
+
     methodinvs = MethodInvalidations[]
+    delayed = Pair{Any,MethodInstance}[]   # from "insert_backedges" invalidations
     leaf = nothing
     mt_backedges, backedges, mt_cache, mt_disable = methinv_storage()
     reason = nothing
@@ -320,8 +355,13 @@ function invalidation_trees(list; exclude_corecompiler::Bool=true)
                         end
                         leaf = nothing
                     end
+                elseif loctag == "insert_backedges_callee"
+                    i = handle_insert_backedges(list, i, mi)
                 elseif loctag == "insert_backedges"
+                    # pre Julia 1.8
                     println("insert_backedges for ", mi)
+                    Base.VERSION < v"1.8.0-DEV" || error("unexpected failure at ", i)
+                    @assert leaf === nothing
                 else
                     error("unexpected loctag ", loctag, " at ", i)
                 end
@@ -348,17 +388,51 @@ function invalidation_trees(list; exclude_corecompiler::Bool=true)
             leaf = nothing
             reason = nothing
         elseif isa(item, Type)
-            root = getroot(leaf)
-            if !exclude_corecompiler || !from_corecompiler(root.mi)
-                push!(mt_backedges, item=>root)
+            if length(list) > i && list[i+1] == "insert_backedges_callee"
+                i = handle_insert_backedges(list, i+1, item)
+            else
+                root = getroot(leaf)
+                if !exclude_corecompiler || !from_corecompiler(root.mi)
+                    push!(mt_backedges, item=>root)
+                end
+                leaf = nothing
             end
-            leaf = nothing
         elseif isa(item, Core.TypeMapEntry) && list[i+1] == "invalidate_mt_cache"
             i += 1
         else
             error("unexpected item ", item, " at ", i)
         end
     end
+    @assert all(isempty, Any[mt_backedges, backedges, #= mt_cache, =# mt_disable])
+    # Handle the delayed invalidations
+    callee2idx = Dict{Method,Int}()
+    for (i, methinvs) in enumerate(methodinvs)
+        for (sig, root) in methinvs.mt_backedges
+            for node in PreOrderDFS(root)
+                callee2idx[MethodInstance(node).def] = i
+            end
+        end
+        for root in methinvs.backedges
+            for node in PreOrderDFS(root)
+                callee2idx[MethodInstance(node).def] = i
+            end
+        end
+    end
+    trouble = similar(delayed, 0)
+    for (callee, caller) in delayed
+        if isa(callee, MethodInstance)
+            idx = get(callee2idx, callee.def, nothing)
+            if idx !== nothing
+                push!(methodinvs[idx].mt_backedges, callee => caller)
+                continue
+            end
+        end
+        push!(trouble, callee => caller)
+    end
+    if !isempty(trouble)
+        @warn "Could not attribute the following delayed invalidations:"
+        display(trouble)
+    end
     return sort!(methodinvs; by=countchildren)
 end
 
@@ -402,7 +476,8 @@ function filtermod(mod::Module, methinvs::MethodInvalidations; recursive::Bool=f
     end
     mt_backedges = filter(pr->hasmod(mod, pr.second), methinvs.mt_backedges)
     backedges = filter(root->hasmod(mod, root), methinvs.backedges)
-    return MethodInvalidations(methinvs.method, methinvs.reason, mt_backedges, backedges, copy(methinvs.mt_cache), copy(methinvs.mt_disable))
+    return MethodInvalidations(methinvs.method, methinvs.reason, mt_backedges, backedges,
+                               copy(methinvs.mt_cache), copy(methinvs.mt_disable))
 end
 
 function filtermod(mod::Module, node::InstanceNode)
@@ -428,6 +503,14 @@ function filtermod(mod::Module, node::InstanceNode)
     return nothing
 end
 
+function filtermod(mod::Module, mi::MethodInstance)
+    m = mi.def
+    if isa(m, Method)
+        return m.module == mod ? mi : nothing
+    end
+    return m == mod ? mi : nothing
+end
+
 """
     methinvs = findcaller(method::Method, trees)
 
@@ -491,12 +574,14 @@ function findcaller(meth::Method, methinvs::MethodInvalidations)
     for (sig, node) in methinvs.mt_backedges
         ret = findcaller(meth, node)
         ret === nothing && continue
-        return MethodInvalidations(methinvs.method, methinvs.reason, [Pair{Any,InstanceNode}(sig, newtree(ret))], InstanceNode[], copy(methinvs.mt_cache), copy(methinvs.mt_disable))
+        return MethodInvalidations(methinvs.method, methinvs.reason, [Pair{Any,InstanceNode}(sig, newtree(ret))], InstanceNode[],
+                                   copy(methinvs.mt_cache), copy(methinvs.mt_disable))
     end
     for node in methinvs.backedges
         ret = findcaller(meth, node)
         ret === nothing && continue
-        return MethodInvalidations(methinvs.method, methinvs.reason, Pair{Any,InstanceNode}[], [newtree(ret)], copy(methinvs.mt_cache), copy(methinvs.mt_disable))
+        return MethodInvalidations(methinvs.method, methinvs.reason, Pair{Any,InstanceNode}[], [newtree(ret)],
+                                   copy(methinvs.mt_cache), copy(methinvs.mt_disable))
     end
     return nothing
 end
@@ -513,6 +598,8 @@ function findcaller(meth::Method, node::InstanceNode)
     return nothing
 end
 
+findcaller(meth::Method, mi::MethodInstance) = mi.def == meth ? mi : nothing
+
 # Cthulhu integration
 
 Cthulhu.backedges(node::InstanceNode) = sort(node.children; by=countchildren, rev=true)

test/snoopi_deep.jl

@@ -6,6 +6,7 @@ using Random
 using Profile
 using MethodAnalysis
 using Core: MethodInstance
+using Pkg
 # using PyPlot: PyPlot, plt    # uncomment to test visualizations
 
 using SnoopCompile.FlameGraphs.AbstractTrees  # For FlameGraphs tests
@@ -780,3 +781,32 @@ end
     @test dmp.trtd == 0
     # pgdsgui(axs[2], rit; bystr="Inclusive", consts=true, interactive=false)
 end
+
+@testset "Stale" begin
+    if Base.VERSION >= v"1.8.0-DEV.368"
+        cproj = Base.active_project()
+        cd(joinpath("testmodules", "Stale")) do
+            Pkg.activate(pwd())
+            Pkg.precompile()
+        end
+        invalidations = @snoopr begin
+            using StaleA, StaleC
+            using StaleB
+        end
+        smis = filter(SnoopCompile.hasstaleinstance, methodinstances(StaleA))
+        @test length(smis) == 2
+        stalenames = [mi.def.name for mi in smis]
+        @test :build_stale ∈ stalenames
+        @test :use_stale ∈ stalenames
+        trees = invalidation_trees(invalidations)
+        tree = only(trees)
+        @test tree.method == which(StaleA.stale, (String,))   # defined in StaleC
+        @test Core.MethodInstance(only(tree.backedges)).def == which(StaleA.stale, (Any,))
+        if Base.VERSION > v"1.8.0-DEV"   # FIXME
+            @test only(tree.mt_backedges).first.def == which(StaleA.stale, (Any,))
+            @test which(only(tree.mt_backedges).first.specTypes) == which(StaleA.stale, (String,))
+            @test only(tree.mt_backedges).second.def == which(StaleB.useA, ())
+        end
+        Pkg.activate(cproj)
+    end
+end

test/testmodules/Stale/Project.toml

@@ -0,0 +1,4 @@
+[deps]
+StaleA = "daf834c3-b832-4a67-a95b-01ec1ffe9b4d"
+StaleB = "af730a9e-e668-4d07-a0f0-de54196c2067"
+StaleC = "f6b5ece7-60fa-49fc-ba7e-b783050e37f1"

test/testmodules/Stale/StaleA/Project.toml

@@ -0,0 +1,4 @@
+name = "StaleA"
+uuid = "daf834c3-b832-4a67-a95b-01ec1ffe9b4d"
+authors = ["Tim Holy <[email protected]>"]
+version = "0.1.0"

test/testmodules/Stale/StaleA/src/StaleA.jl

@@ -0,0 +1,15 @@
+module StaleA
+
+stale(x) = rand(1:8)
+stale(x::Int) = length(digits(x))
+
+not_stale(x::String) = first(x)
+
+use_stale(c) = stale(c[1]) + not_stale("hello")
+build_stale(x) = use_stale(Any[x])
+
+# force precompilation
+build_stale(37)
+stale('c')
+
+end

test/testmodules/Stale/StaleB/Project.toml

@@ -0,0 +1,8 @@
+name = "StaleB"
+uuid = "af730a9e-e668-4d07-a0f0-de54196c2067"
+authors = ["Tim Holy <[email protected]>"]
+version = "0.1.0"
+
+[deps]
+StaleA = "daf834c3-b832-4a67-a95b-01ec1ffe9b4d"
+StaleC = "f6b5ece7-60fa-49fc-ba7e-b783050e37f1"

test/testmodules/Stale/StaleB/src/StaleB.jl

@@ -0,0 +1,14 @@
+module StaleB
+
+# StaleB does not know about StaleC when it is being built.
+# However, if StaleC is loaded first, we get `"insert_backedges"`
+# invalidations.
+using StaleA
+
+# This will be invalidated if StaleC is loaded
+useA() = StaleA.stale("hello")
+
+# force precompilation
+useA()
+
+end

test/testmodules/Stale/StaleC/Project.toml

@@ -0,0 +1,7 @@
+name = "StaleC"
+uuid = "f6b5ece7-60fa-49fc-ba7e-b783050e37f1"
+authors = ["Tim Holy <[email protected]>"]
+version = "0.1.0"
+
+[deps]
+StaleA = "daf834c3-b832-4a67-a95b-01ec1ffe9b4d"

test/testmodules/Stale/StaleC/src/StaleC.jl

@@ -0,0 +1,10 @@
+module StaleC
+
+using StaleA
+
+StaleA.stale(x::String) = length(x)
+call_buildstale(x) = StaleA.build_stale(x)
+
+call_buildstale("hey")
+
+end # module