add METHOD_SIG_LATEST_ONLY optimization to MethodInstance too (#58825)

Add the same optimization from Method to MethodInstance, although the
performance gain seems to be negligible in my specific testing, there
doesn't seem any likely downside to adding one caching bit to avoid some
recomputations.

Author: vtjnash

base/essentials.jl

@@ -731,7 +731,7 @@ Neither `convert` nor `cconvert` should take a Julia object and turn it into a `
 """
 function cconvert end
 
-cconvert(T::Type, x) = x isa T ? x : convert(T, x) # do the conversion eagerly in most cases
+cconvert(::Type{T}, x) where {T} = x isa T ? x : convert(T, x) # do the conversion eagerly in most cases
 cconvert(::Type{Union{}}, x...) = convert(Union{}, x...)
 cconvert(::Type{<:Ptr}, x) = x # but defer the conversion to Ptr to unsafe_convert
 unsafe_convert(::Type{T}, x::T) where {T} = x # unsafe_convert (like convert) defaults to assuming the convert occurred

base/staticdata.jl

@@ -281,6 +281,7 @@ end
 
 function verify_call(@nospecialize(sig), expecteds::Core.SimpleVector, i::Int, n::Int, world::UInt)
     # verify that these edges intersect with the same methods as before
+    mi = nothing
     if n == 1
         # first, fast-path a check if the expected method simply dominates its sig anyways
         # so the result of ml_matches is already simply known
@@ -289,11 +290,18 @@ function verify_call(@nospecialize(sig), expecteds::Core.SimpleVector, i::Int, n
                 meth = t
             else
                 if t isa CodeInstance
-                    t = get_ci_mi(t)
+                    mi = get_ci_mi(t)::MethodInstance
                 else
-                    t = t::MethodInstance
+                    mi = t::MethodInstance
+                end
+                meth = mi.def::Method
+                if !iszero(mi.dispatch_status & METHOD_SIG_LATEST_ONLY)
+                    minworld = meth.primary_world
+                    @assert minworld ≤ world
+                    maxworld = typemax(UInt)
+                    result = Any[] # result is unused
+                    return minworld, maxworld, result
                 end
-                meth = t.def::Method
             end
             if !iszero(meth.dispatch_status & METHOD_SIG_LATEST_ONLY)
                 minworld = meth.primary_world
@@ -327,7 +335,7 @@ function verify_call(@nospecialize(sig), expecteds::Core.SimpleVector, i::Int, n
                     meth = t
                 else
                     if t isa CodeInstance
-                        t = get_ci_mi(t)
+                        t = get_ci_mi(t)::MethodInstance
                     else
                         t = t::MethodInstance
                     end
@@ -354,6 +362,9 @@ function verify_call(@nospecialize(sig), expecteds::Core.SimpleVector, i::Int, n
             resize!(result, ins)
         end
     end
+    if maxworld[] == typemax(UInt) && mi isa MethodInstance
+        ccall(:jl_promote_mi_to_current, Cvoid, (Any, UInt, UInt), mi, minworld[], world)
+    end
     return minworld[], maxworld[], result
 end
 

doc/src/devdocs/locks.md

@@ -85,6 +85,10 @@ may result in pernicious and hard-to-find deadlocks. BE VERY CAREFUL!
 >
 >   * Libdl.LazyLibrary lock
 
+The following is a level 7 lock, which can only be acquired when not holding any other locks:
+
+>   * world_counter_lock
+
 
 The following is the root lock, meaning no other lock shall be held when trying to acquire it:
 

src/gf.c

@@ -3575,7 +3575,7 @@ void jl_init_types(void) JL_GC_DISABLED
                             jl_module_type,
                             jl_symbol_type,
                             jl_int32_type,
-                            jl_int32_type,
+                            jl_uint8_type,
                             jl_ulong_type,
                             jl_type_type,
                             jl_any_type, // union(jl_simplevector_type, jl_method_instance_type),
@@ -3613,27 +3613,29 @@ void jl_init_types(void) JL_GC_DISABLED
     jl_method_instance_type =
         jl_new_datatype(jl_symbol("MethodInstance"), core,
                         jl_any_type, jl_emptysvec,
-                        jl_perm_symsvec(7,
+                        jl_perm_symsvec(8,
                             "def",
                             "specTypes",
                             "sparam_vals",
                             "backedges",
                             "cache",
                             "cache_with_orig",
-                            "flags"),
-                        jl_svec(7,
+                            "flags",
+                            "dispatch_status"),
+                        jl_svec(8,
                             jl_new_struct(jl_uniontype_type, jl_method_type, jl_module_type),
                             jl_any_type,
                             jl_simplevector_type,
                             jl_array_any_type,
                             jl_any_type/*jl_code_instance_type*/,
                             jl_bool_type,
-                            jl_bool_type),
+                            jl_bool_type,
+                            jl_uint8_type),
                         jl_emptysvec,
                         0, 1, 3);
     // These fields should be constant, but Serialization wants to mutate them in initialization
     //const static uint32_t method_instance_constfields[1] = { 0b0000111 }; // fields 1, 2, 3
-    const static uint32_t method_instance_atomicfields[1]  = { 0b1010000 }; // fields 5, 7
+    const static uint32_t method_instance_atomicfields[1]  = { 0b11010000 }; // fields 5, 7, 8
     //Fields 4 and 5 must be protected by method->write_lock, and thus all operations on jl_method_instance_t are threadsafe.
     //jl_method_instance_type->name->constfields = method_instance_constfields;
     jl_method_instance_type->name->atomicfields = method_instance_atomicfields;

src/jltypes.c

@@ -323,7 +323,7 @@ typedef struct _jl_method_t {
     struct _jl_module_t *module;
     jl_sym_t *file;
     int32_t line;
-    _Atomic(int32_t) dispatch_status; // bits defined in staticdata.jl
+    _Atomic(uint8_t) dispatch_status; // bits defined in staticdata.jl
     _Atomic(size_t) primary_world;
 
     // method's type signature. redundant with TypeMapEntry->specTypes
@@ -408,6 +408,7 @@ struct _jl_method_instance_t {
     //   bit 2: The ->backedges field is currently being walked higher up the stack - entries may be deleted, but not moved
     //   bit 3: The ->backedges field was modified and should be compacted when clearing bit 2
     _Atomic(uint8_t) flags;
+    _Atomic(uint8_t) dispatch_status; // bits defined in staticdata.jl
 };
 #define JL_MI_FLAGS_MASK_PRECOMPILED    0x01
 #define JL_MI_FLAGS_MASK_DISPATCHED     0x02

src/julia.h

@@ -609,6 +609,7 @@ JL_DLLEXPORT jl_method_instance_t *jl_new_method_instance_uninit(void)
     jl_atomic_store_relaxed(&mi->cache, NULL);
     mi->cache_with_orig = 0;
     jl_atomic_store_relaxed(&mi->flags, 0);
+    jl_atomic_store_relaxed(&mi->dispatch_status, 0);
     return mi;
 }
 

src/method.c

@@ -1853,6 +1853,9 @@ static void jl_write_values(jl_serializer_state *s) JL_GC_DISABLED
                 assert(f == s->s);
                 jl_method_instance_t *newmi = (jl_method_instance_t*)&f->buf[reloc_offset];
                 jl_atomic_store_relaxed(&newmi->flags, 0);
+                if (s->incremental) {
+                    jl_atomic_store_relaxed(&newmi->dispatch_status, 0);
+                }
             }
             else if (jl_is_code_instance(v)) {
                 assert(f == s->s);
@@ -4547,49 +4550,6 @@ JL_DLLEXPORT jl_value_t *jl_restore_package_image_from_file(const char *fname, j
     return mod;
 }
 
-JL_DLLEXPORT void _jl_promote_ci_to_current(jl_code_instance_t *ci, size_t validated_world) JL_NOTSAFEPOINT
-{
-    if (jl_atomic_load_relaxed(&ci->max_world) != validated_world)
-        return;
-    jl_atomic_store_relaxed(&ci->max_world, ~(size_t)0);
-    jl_svec_t *edges = jl_atomic_load_relaxed(&ci->edges);
-    for (size_t i = 0; i < jl_svec_len(edges); i++) {
-        jl_value_t *edge = jl_svecref(edges, i);
-        if (!jl_is_code_instance(edge))
-            continue;
-        _jl_promote_ci_to_current((jl_code_instance_t *)edge, validated_world);
-    }
-}
-
-JL_DLLEXPORT void jl_promote_ci_to_current(jl_code_instance_t *ci, size_t validated_world)
-{
-    size_t current_world = jl_atomic_load_relaxed(&jl_world_counter);
-    // No need to acquire the lock if we've been invalidated anyway
-    if (current_world > validated_world)
-        return;
-    JL_LOCK(&world_counter_lock);
-    current_world = jl_atomic_load_relaxed(&jl_world_counter);
-    if (current_world == validated_world) {
-        _jl_promote_ci_to_current(ci, validated_world);
-    }
-    JL_UNLOCK(&world_counter_lock);
-}
-
-JL_DLLEXPORT void jl_promote_cis_to_current(jl_code_instance_t **cis, size_t n, size_t validated_world)
-{
-    size_t current_world = jl_atomic_load_relaxed(&jl_world_counter);
-    // No need to acquire the lock if we've been invalidated anyway
-    if (current_world > validated_world)
-        return;
-    JL_LOCK(&world_counter_lock);
-    current_world = jl_atomic_load_relaxed(&jl_world_counter);
-    if (current_world == validated_world) {
-        for (size_t i = 0; i < n; i++) {
-            _jl_promote_ci_to_current(cis[i], validated_world);
-        }
-    }
-    JL_UNLOCK(&world_counter_lock);
-}
 
 #ifdef __cplusplus
 }

src/staticdata.c

@@ -37,7 +37,7 @@ for (T, c) in (
         (Core.CodeInfo, []),
         (Core.CodeInstance, [:next, :min_world, :max_world, :inferred, :edges, :debuginfo, :ipo_purity_bits, :invoke, :specptr, :specsigflags, :precompile, :time_compile]),
         (Core.Method, [:primary_world, :did_scan_source, :dispatch_status]),
-        (Core.MethodInstance, [:cache, :flags]),
+        (Core.MethodInstance, [:cache, :flags, :dispatch_status]),
         (Core.MethodTable, [:defs]),
         (Core.MethodCache, [:leafcache, :cache, :var""]),
         (Core.TypeMapEntry, [:next, :min_world, :max_world]),