Give const prop'ed calls their own statement info (JuliaLang#39754)

Keno · ElOceanografo · commit 0afd997761f4 · 2021-05-04T00:05:38.000-07:00
My primary motivation here is to let Cthulhu mark cases
where constant propagation improved the result, but this
also lets us avoid the second (linear) lookup in the
inference cache, which causes a marginal, but measurable
(a few percent) improvement in sysimage build time.
diff --git a/base/compiler/abstractinterpretation.jl b/base/compiler/abstractinterpretation.jl
@@ -166,11 +166,14 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(f),
         # if there's a possibility we could constant-propagate a better result
         # (hopefully without doing too much work), try to do that now
         # TODO: it feels like this could be better integrated into abstract_call_method / typeinf_edge
-        const_rettype = abstract_call_method_with_const_args(interp, rettype, f, argtypes, applicable[nonbot]::MethodMatch, sv, edgecycle)
+        const_rettype, result = abstract_call_method_with_const_args(interp, rettype, f, argtypes, applicable[nonbot]::MethodMatch, sv, edgecycle)
         if const_rettype ⊑ rettype
             # use the better result, if it's a refinement of rettype
             rettype = const_rettype
         end
+        if result !== nothing
+            info = ConstCallInfo(info, result)
+        end
     end
     if is_unused && !(rettype === Bottom)
         add_remark!(interp, sv, "Call result type was widened because the return value is unused")
@@ -263,7 +266,7 @@ function abstract_call_method_with_const_args(interp::AbstractInterpreter, @nosp
     method = match.method
     nargs::Int = method.nargs
     method.isva && (nargs -= 1)
-    length(argtypes) >= nargs || return Any
+    length(argtypes) >= nargs || return Any, nothing
     haveconst = false
     allconst = true
     # see if any or all of the arguments are constant and propagating constants may be worthwhile
@@ -279,21 +282,21 @@ function abstract_call_method_with_const_args(interp::AbstractInterpreter, @nosp
             break
         end
     end
-    haveconst || improvable_via_constant_propagation(rettype) || return Any
+    haveconst || improvable_via_constant_propagation(rettype) || return Any, nothing
     force_inference = method.aggressive_constprop || InferenceParams(interp).aggressive_constant_propagation
     if !force_inference && nargs > 1
         if istopfunction(f, :getindex) || istopfunction(f, :setindex!)
             arrty = argtypes[2]
             # don't propagate constant index into indexing of non-constant array
             if arrty isa Type && arrty <: AbstractArray && !issingletontype(arrty)
-                return Any
+                return Any, nothing
             elseif arrty ⊑ Array
-                return Any
+                return Any, nothing
             end
         elseif istopfunction(f, :iterate)
             itrty = argtypes[2]
             if itrty ⊑ Array
-                return Any
+                return Any, nothing
             end
         end
     end
@@ -304,7 +307,7 @@ function abstract_call_method_with_const_args(interp::AbstractInterpreter, @nosp
          istopfunction(f, :<<) || istopfunction(f, :>>))
         # it is almost useless to inline the op of when all the same type,
         # but highly worthwhile to inline promote of a constant
-        length(argtypes) > 2 || return Any
+        length(argtypes) > 2 || return Any, nothing
         t1 = widenconst(argtypes[2])
         all_same = true
         for i in 3:length(argtypes)
@@ -313,18 +316,18 @@ function abstract_call_method_with_const_args(interp::AbstractInterpreter, @nosp
                 break
             end
         end
-        all_same && return Any
+        all_same && return Any, nothing
     end
     if istopfunction(f, :getproperty) || istopfunction(f, :setproperty!)
         force_inference = true
     end
     force_inference |= allconst
     mi = specialize_method(match, !force_inference)
-    mi === nothing && return Any
+    mi === nothing && return Any, nothing
     mi = mi::MethodInstance
     # decide if it's likely to be worthwhile
     if !force_inference && !const_prop_heuristic(interp, method, mi)
-        return Any
+        return Any, nothing
     end
     inf_cache = get_inference_cache(interp)
     inf_result = cache_lookup(mi, argtypes, inf_cache)
@@ -336,7 +339,7 @@ function abstract_call_method_with_const_args(interp::AbstractInterpreter, @nosp
             cyclei = 0
             while !(infstate === nothing)
                 if method === infstate.linfo.def && any(infstate.result.overridden_by_const)
-                    return Any
+                    return Any, nothing
                 end
                 if cyclei < length(infstate.callers_in_cycle)
                     cyclei += 1
@@ -349,16 +352,16 @@ function abstract_call_method_with_const_args(interp::AbstractInterpreter, @nosp
         end
         inf_result = InferenceResult(mi, argtypes)
         frame = InferenceState(inf_result, #=cache=#false, interp)
-        frame === nothing && return Any # this is probably a bad generated function (unsound), but just ignore it
+        frame === nothing && return Any, nothing # this is probably a bad generated function (unsound), but just ignore it
         frame.parent = sv
         push!(inf_cache, inf_result)
-        typeinf(interp, frame) || return Any
+        typeinf(interp, frame) || return Any, nothing
     end
     result = inf_result.result
     # if constant inference hits a cycle, just bail out
-    isa(result, InferenceState) && return Any
+    isa(result, InferenceState) && return Any, nothing
     add_backedge!(inf_result.linfo, sv)
-    return result
+    return result, inf_result
 end
 
 const RECURSION_UNUSED_MSG = "Bounded recursion detected with unused result. Annotated return type may be wider than true result."
diff --git a/base/compiler/ssair/inlining.jl b/base/compiler/ssair/inlining.jl
@@ -33,7 +33,7 @@ end
     pass to apply its own inlining policy decisions.
 """
 struct DelayedInliningSpec
-    match::MethodMatch
+    match::Union{MethodMatch, InferenceResult}
     atypes::Vector{Any}
     stmttype::Any
 end
@@ -44,7 +44,11 @@ struct InliningTodo
     spec::Union{ResolvedInliningSpec, DelayedInliningSpec}
 end
 
-InliningTodo(mi::MethodInstance, match::MethodMatch, atypes::Vector{Any}, @nospecialize(stmttype)) = InliningTodo(mi, DelayedInliningSpec(match, atypes, stmttype))
+InliningTodo(mi::MethodInstance, match::MethodMatch,
+    atypes::Vector{Any}, @nospecialize(stmttype)) = InliningTodo(mi, DelayedInliningSpec(match, atypes, stmttype))
+
+InliningTodo(result::InferenceResult, atypes::Vector{Any}, @nospecialize(stmttype)) =
+    InliningTodo(result.linfo, DelayedInliningSpec(result, atypes, stmttype))
 
 struct ConstantCase
     val::Any
@@ -631,7 +635,10 @@ function rewrite_apply_exprargs!(ir::IRCode, todo::Vector{Pair{Int, Any}}, idx::
                 new_stmt = Expr(:call, argexprs[2], def, state...)
                 state1 = insert_node!(ir, idx, call.rt, new_stmt)
                 new_sig = with_atype(call_sig(ir, new_stmt)::Signature)
-                if isa(call.info, MethodMatchInfo) || isa(call.info, UnionSplitInfo)
+                if isa(call.info, ConstCallInfo)
+                    handle_const_call!(ir, state1.id, new_stmt, call.info, new_sig,
+                        call.rt, et, caches, false, todo)
+                elseif isa(call.info, MethodMatchInfo) || isa(call.info, UnionSplitInfo)
                     info = isa(call.info, MethodMatchInfo) ?
                         MethodMatchInfo[call.info] : call.info.matches
                     # See if we can inline this call to `iterate`
@@ -676,9 +683,32 @@ function compileable_specialization(et::Union{EdgeTracker, Nothing}, match::Meth
     return mi
 end
 
+function compileable_specialization(et::Union{EdgeTracker, Nothing}, result::InferenceResult)
+    mi = specialize_method(result.linfo.def, result.linfo.specTypes,
+        result.linfo.sparam_vals, false, true)
+    mi !== nothing && et !== nothing && push!(et, mi::MethodInstance)
+    return mi
+end
+
 function resolve_todo(todo::InliningTodo, et::Union{EdgeTracker, Nothing}, caches::InferenceCaches)
     spec = todo.spec::DelayedInliningSpec
-    isconst, src = find_inferred(todo.mi, spec.atypes, caches, spec.stmttype)
+
+    #XXX: update_valid_age!(min_valid[1], max_valid[1], sv)
+    isconst, src = false, nothing
+    if isa(spec.match, InferenceResult)
+        let inferred_src = spec.match.src
+            if isa(inferred_src, CodeInfo)
+                isconst, src = false, inferred_src
+            elseif isa(inferred_src, Const)
+                if !is_inlineable_constant(inferred_src.val)
+                    return compileable_specialization(et, spec.match)
+                end
+                isconst, src = true, quoted(inferred_src.val)
+            end
+        end
+    else
+        isconst, src = find_inferred(todo.mi, spec.atypes, caches, spec.stmttype)
+    end
 
     if isconst && et !== nothing
         push!(et, todo.mi)
@@ -717,6 +747,13 @@ function resolve_todo!(todo::Vector{Pair{Int, Any}}, et::Union{EdgeTracker, Noth
     todo
 end
 
+function validate_sparams(sparams::SimpleVector)
+    for i = 1:length(sparams)
+        (isa(sparams[i], TypeVar) || isa(sparams[i], Core.TypeofVararg)) && return false
+    end
+    return true
+end
+
 function analyze_method!(match::MethodMatch, atypes::Vector{Any},
                          et::Union{EdgeTracker, Nothing},
                          caches::Union{InferenceCaches, Nothing},
@@ -737,9 +774,8 @@ function analyze_method!(match::MethodMatch, atypes::Vector{Any},
 
     # Bail out if any static parameters are left as TypeVar
     ok = true
-    for i = 1:length(match.sparams)
-        (isa(match.sparams[i], TypeVar) || isa(match.sparams[i], Core.TypeofVararg)) && return nothing
-    end
+    validate_sparams(match.sparams) || return nothing
+
 
     if !params.inlining
         return compileable_specialization(et, match)
@@ -1146,6 +1182,28 @@ function analyze_single_call!(ir::IRCode, todo::Vector{Pair{Int, Any}}, idx::Int
     return nothing
 end
 
+function handle_const_call!(ir::IRCode, idx::Int, stmt::Expr,
+        info::ConstCallInfo, sig::Signature, @nospecialize(calltype),
+        et::Union{EdgeTracker, Nothing}, caches::Union{InferenceCaches, Nothing},
+        isinvoke::Bool, todo::Vector{Pair{Int, Any}})
+    item = InliningTodo(info.result, sig.atypes, calltype)
+    validate_sparams(item.mi.sparam_vals) || return
+    mthd_sig = item.mi.def.sig
+    mistypes = item.mi.specTypes
+    caches !== nothing && (item = resolve_todo(item, et, caches))
+    if sig.atype <: mthd_sig
+        return handle_single_case!(ir, stmt, idx, item, isinvoke, todo)
+    else
+        item === nothing && return
+        # Union split out the error case
+        item = UnionSplit(false, sig.atype, Pair{Any, Any}[mistypes => item])
+        if isinvoke
+            stmt.args = rewrite_invoke_exprargs!(stmt.args)
+        end
+        push!(todo, idx=>item)
+    end
+end
+
 function assemble_inline_todo!(ir::IRCode, state::InliningState)
     # todo = (inline_idx, (isva, isinvoke, na), method, spvals, inline_linetable, inline_ir, lie)
     todo = Pair{Int, Any}[]
@@ -1173,6 +1231,15 @@ function assemble_inline_todo!(ir::IRCode, state::InliningState)
             end
         end
 
+        # If inference arrived at this result by using constant propagation,
+        # it'll performed a specialized analysis for just this case. Use its
+        # result.
+        if isa(info, ConstCallInfo)
+            handle_const_call!(ir, idx, stmt, info, sig, calltype, state.et,
+                state.caches, invoke_data !== nothing, todo)
+            continue
+        end
+
         # Ok, now figure out what method to call
         if invoke_data !== nothing
             inline_invoke!(ir, idx, sig, invoke_data, state, todo)
@@ -1387,35 +1454,6 @@ function ssa_substitute_op!(@nospecialize(val), arg_replacements::Vector{Any},
 end
 
 function find_inferred(mi::MethodInstance, atypes::Vector{Any}, caches::InferenceCaches, @nospecialize(rettype))
-    if caches.inf_cache !== nothing
-        # see if the method has a InferenceResult in the current cache
-        # or an existing inferred code info store in `.inferred`
-        haveconst = false
-        for i in 1:length(atypes)
-            if has_nontrivial_const_info(atypes[i])
-                # have new information from argtypes that wasn't available from the signature
-                haveconst = true
-                break
-            end
-        end
-        if haveconst || improvable_via_constant_propagation(rettype)
-            inf_result = cache_lookup(mi, atypes, caches.inf_cache) # Union{Nothing, InferenceResult}
-        else
-            inf_result = nothing
-        end
-        #XXX: update_valid_age!(min_valid[1], max_valid[1], sv)
-        if isa(inf_result, InferenceResult)
-            let inferred_src = inf_result.src
-                if isa(inferred_src, CodeInfo)
-                    return svec(false, inferred_src)
-                end
-                if isa(inferred_src, Const) && is_inlineable_constant(inferred_src.val)
-                    return svec(true, quoted(inferred_src.val),)
-                end
-            end
-        end
-    end
-
     linfo = get(caches.mi_cache, mi, nothing)
     if linfo isa CodeInstance
         if invoke_api(linfo) == 2
diff --git a/base/compiler/stmtinfo.jl b/base/compiler/stmtinfo.jl
@@ -82,6 +82,18 @@ struct UnionSplitApplyCallInfo
     infos::Vector{ApplyCallInfo}
 end
 
+"""
+    struct ConstCallInfo
+
+Precision for this call was improved using constant information. This info
+keeps a reference to the result that was used (or created for these)
+constant information.
+"""
+struct ConstCallInfo
+    call::Any
+    result::InferenceResult
+end
+
 # Stmt infos that are used by external consumers, but not by optimization.
 # These are not produced by default and must be explicitly opted into by
 # the AbstractInterpreter.
diff --git a/base/compiler/typeutils.jl b/base/compiler/typeutils.jl
@@ -234,7 +234,7 @@ function unswitchtupleunion(u::Union)
     ts = uniontypes(u)
     n = -1
     for t in ts
-        if t isa DataType && t.name === Tuple.name && !isvarargtype(t.parameters[end])
+        if t isa DataType && t.name === Tuple.name && length(t.parameters) != 0 && !isvarargtype(t.parameters[end])
             if n == -1
                 n = length(t.parameters)
             elseif n != length(t.parameters)
