Cache external CodeInstances (#43990)

Prior to this PR, Julia's precompiled `*.ji` files saved just two
categories of code: unspecialized method definitions and
type-specialized code for the methods defined by the package.  Any
novel specializations of methods from Base or previously-loaded
packages were not saved, and therefore effectively thrown away.

This PR caches all the code---internal or external---called during
package definition that hadn't been previously inferred, as long
as there is a backedge linking it back to a method owned by
a module being precompiled. (The latter condition ensures it will
actually be called by package methods, and not merely transiently
generated for the purpose of, e.g., metaprogramming or variable
initialization.) This makes precompilation more intuitive (now it
saves all relevant inference results), and substantially reduces
latency for inference-bound packages.

Closes #42016
Fixes #35972

Issue #35972 arose because codegen got started without re-inferring
some discarded CodeInstances. This forced the compiler to insert a
`jl_invoke`. This PR fixes the issue because needed CodeInstances are
no longer discarded by precompilation.

base/Base.jl

@@ -427,7 +427,7 @@ end_base_include = time_ns()
 const _sysimage_modules = PkgId[]
 in_sysimage(pkgid::PkgId) = pkgid in _sysimage_modules
 
-# Precompiles for Revise
+# Precompiles for Revise and other packages
 # TODO: move these to contrib/generate_precompile.jl
 # The problem is they don't work there
 for match = _methods(+, (Int, Int), -1, get_world_counter())
@@ -461,6 +461,23 @@ for match = _methods(+, (Int, Int), -1, get_world_counter())
 
     # Code loading uses this
     sortperm(mtime.(readdir(".")), rev=true)
+    # JLLWrappers uses these
+    Dict{UUID,Set{String}}()[UUID("692b3bcd-3c85-4b1f-b108-f13ce0eb3210")] = Set{String}()
+    get!(Set{String}, Dict{UUID,Set{String}}(), UUID("692b3bcd-3c85-4b1f-b108-f13ce0eb3210"))
+    eachindex(IndexLinear(), Expr[])
+    push!(Expr[], Expr(:return, false))
+    vcat(String[], String[])
+    k, v = (:hello => nothing)
+    precompile(indexed_iterate, (Pair{Symbol, Union{Nothing, String}}, Int))
+    precompile(indexed_iterate, (Pair{Symbol, Union{Nothing, String}}, Int, Int))
+    # Preferences uses these
+    precompile(get_preferences, (UUID,))
+    precompile(record_compiletime_preference, (UUID, String))
+    get(Dict{String,Any}(), "missing", nothing)
+    delete!(Dict{String,Any}(), "missing")
+    for (k, v) in Dict{String,Any}()
+        println(k)
+    end
 
     break   # only actually need to do this once
 end

base/binaryplatforms.jl

@@ -40,10 +40,10 @@ struct Platform <: AbstractPlatform
     # The "compare strategy" allows selective overriding on how a tag is compared
     compare_strategies::Dict{String,Function}
 
-    function Platform(arch::String, os::String;
+    # Passing `tags` as a `Dict` avoids the need to infer different NamedTuple specializations
+    function Platform(arch::String, os::String, _tags::Dict{String};
                       validate_strict::Bool = false,
-                      compare_strategies::Dict{String,<:Function} = Dict{String,Function}(),
-                      kwargs...)
+                      compare_strategies::Dict{String,<:Function} = Dict{String,Function}())
         # A wee bit of normalization
         os = lowercase(os)
         arch = CPUID.normalize_arch(arch)
@@ -52,8 +52,9 @@ struct Platform <: AbstractPlatform
             "arch" => arch,
             "os" => os,
         )
-        for (tag, value) in kwargs
-            tag = lowercase(string(tag::Symbol))
+        for (tag, value) in _tags
+            value = value::Union{String,VersionNumber,Nothing}
+            tag = lowercase(tag)
             if tag ∈ ("arch", "os")
                 throw(ArgumentError("Cannot double-pass key $(tag)"))
             end
@@ -70,8 +71,8 @@ struct Platform <: AbstractPlatform
             if tag ∈ ("libgfortran_version", "libstdcxx_version", "os_version")
                 if isa(value, VersionNumber)
                     value = string(value)
-                elseif isa(value, AbstractString)
-                    v = tryparse(VersionNumber, String(value)::String)
+                elseif isa(value, String)
+                    v = tryparse(VersionNumber, value)
                     if isa(v, VersionNumber)
                         value = string(v)
                     end
@@ -110,6 +111,19 @@ struct Platform <: AbstractPlatform
     end
 end
 
+# Keyword interface (to avoid inference of specialized NamedTuple methods, use the Dict interface for `tags`)
+function Platform(arch::String, os::String;
+                  validate_strict::Bool = false,
+                  compare_strategies::Dict{String,<:Function} = Dict{String,Function}(),
+                  kwargs...)
+    tags = Dict{String,Any}(String(tag)::String=>tagvalue(value) for (tag, value) in kwargs)
+    return Platform(arch, os, tags; validate_strict, compare_strategies)
+end
+
+tagvalue(v::Union{String,VersionNumber,Nothing}) = v
+tagvalue(v::Symbol) = String(v)
+tagvalue(v::AbstractString) = convert(String, v)::String
+
 # Simple tag insertion that performs a little bit of validation
 function add_tag!(tags::Dict{String,String}, tag::String, value::String)
     # I know we said only alphanumeric and dots, but let's be generous so that we can expand
@@ -699,21 +713,22 @@ function Base.parse(::Type{Platform}, triplet::AbstractString; validate_strict::
         end
 
         # Extract the information we're interested in:
+        tags = Dict{String,Any}()
         arch = get_field(m, arch_mapping)
         os = get_field(m, os_mapping)
-        libc = get_field(m, libc_mapping)
-        call_abi = get_field(m, call_abi_mapping)
-        libgfortran_version = get_field(m, libgfortran_version_mapping)
-        libstdcxx_version = get_field(m, libstdcxx_version_mapping)
-        cxxstring_abi = get_field(m, cxxstring_abi_mapping)
+        tags["libc"] = get_field(m, libc_mapping)
+        tags["call_abi"] = get_field(m, call_abi_mapping)
+        tags["libgfortran_version"] = get_field(m, libgfortran_version_mapping)
+        tags["libstdcxx_version"] = get_field(m, libstdcxx_version_mapping)
+        tags["cxxstring_abi"] = get_field(m, cxxstring_abi_mapping)
         function split_tags(tagstr)
             tag_fields = split(tagstr, "-"; keepempty=false)
             if isempty(tag_fields)
                 return Pair{String,String}[]
             end
-            return map(v -> Symbol(v[1]) => v[2], split.(tag_fields, "+"))
+            return map(v -> String(v[1]) => String(v[2]), split.(tag_fields, "+"))
         end
-        tags = split_tags(m["tags"])
+        merge!(tags, Dict(split_tags(m["tags"])))
 
         # Special parsing of os version number, if any exists
         function extract_os_version(os_name, pattern)
@@ -730,18 +745,9 @@ function Base.parse(::Type{Platform}, triplet::AbstractString; validate_strict::
         if os == "freebsd"
             os_version = extract_os_version("freebsd", r".*freebsd([\d.]+)")
         end
+        tags["os_version"] = os_version
 
-        return Platform(
-            arch, os;
-            validate_strict,
-            libc,
-            call_abi,
-            libgfortran_version,
-            cxxstring_abi,
-            libstdcxx_version,
-            os_version,
-            tags...,
-        )
+        return Platform(arch, os, tags; validate_strict)
     end
     throw(ArgumentError("Platform `$(triplet)` is not an officially supported platform"))
 end
@@ -1068,4 +1074,9 @@ function select_platform(download_info::Dict, platform::AbstractPlatform = HostP
     return download_info[p]
 end
 
+# precompiles to reduce latency (see https://github.com/JuliaLang/julia/pull/43990#issuecomment-1025692379)
+Dict{Platform,String}()[HostPlatform()] = ""
+Platform("x86_64", "linux", Dict{String,Any}(); validate_strict=true)
+Platform("x86_64", "linux", Dict{String,String}(); validate_strict=false)  # called this way from Artifacts.unpack_platform
+
 end # module

base/compiler/typeinfer.jl

@@ -1,5 +1,9 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
+# Tracking of newly-inferred MethodInstances during precompilation
+const track_newly_inferred = RefValue{Bool}(false)
+const newly_inferred = MethodInstance[]
+
 # build (and start inferring) the inference frame for the top-level MethodInstance
 function typeinf(interp::AbstractInterpreter, result::InferenceResult, cache::Symbol)
     frame = InferenceState(result, cache, interp)
@@ -389,6 +393,12 @@ function cache_result!(interp::AbstractInterpreter, result::InferenceResult)
     if !already_inferred
         inferred_result = transform_result_for_cache(interp, linfo, valid_worlds, result.src)
         code_cache(interp)[linfo] = CodeInstance(result, inferred_result, valid_worlds)
+        if track_newly_inferred[]
+            m = linfo.def
+            if isa(m, Method)
+                m.module != Core && push!(newly_inferred, linfo)
+            end
+        end
     end
     unlock_mi_inference(interp, linfo)
     nothing

base/loading.jl

@@ -1395,13 +1395,17 @@ function include_package_for_output(pkg::PkgId, input::String, depot_path::Vecto
         task_local_storage()[:SOURCE_PATH] = source
     end
 
+    Core.Compiler.track_newly_inferred.x = true
     try
         Base.include(Base.__toplevel__, input)
     catch ex
         precompilableerror(ex) || rethrow()
         @debug "Aborting `create_expr_cache'" exception=(ErrorException("Declaration of __precompile__(false) not allowed"), catch_backtrace())
         exit(125) # we define status = 125 means PrecompileableError
+    finally
+        Core.Compiler.track_newly_inferred.x = false
     end
+    ccall(:jl_set_newly_inferred, Cvoid, (Any,), Core.Compiler.newly_inferred)
 end
 
 const PRECOMPILE_TRACE_COMPILE = Ref{String}()
@@ -2033,12 +2037,12 @@ end
 
 Compile the given function `f` for the argument tuple (of types) `args`, but do not execute it.
 """
-function precompile(@nospecialize(f), args::Tuple)
+function precompile(@nospecialize(f), @nospecialize(args::Tuple))
     precompile(Tuple{Core.Typeof(f), args...})
 end
 
 const ENABLE_PRECOMPILE_WARNINGS = Ref(false)
-function precompile(argt::Type)
+function precompile(@nospecialize(argt::Type))
     ret = ccall(:jl_compile_hint, Int32, (Any,), argt) != 0
     if !ret && ENABLE_PRECOMPILE_WARNINGS[]
         @warn "Inactive precompile statement" maxlog=100 form=argt _module=nothing _file=nothing _line=0

src/codegen.cpp

@@ -7870,7 +7870,7 @@ jl_compile_result_t jl_emit_codeinst(
                      // don't delete inlineable code, unless it is constant
                      (codeinst->invoke == jl_fptr_const_return_addr || !jl_ir_flag_inlineable((jl_array_t*)codeinst->inferred)) &&
                      // don't delete code when generating a precompile file
-                     !imaging_mode) {
+                     !(imaging_mode || jl_options.incremental)) {
                 // if not inlineable, code won't be needed again
                 codeinst->inferred = jl_nothing;
             }