Improve codegen for Core.throw_methoderror and Core.current_scope (JuliaLang#55803)

This slightly improves our (LLVM) codegen for `Core.throw_methoderror`
and `Core.current_scope`

```julia
julia> foo() = Core.current_scope()
julia> bar() = Core.throw_methoderror(+, nothing)
```

Before:
```llvm
; Function Signature: foo()
define nonnull ptr @julia_foo_2488() #0 {
top:
  %0 = call ptr @jl_get_builtin_fptr(ptr nonnull @"+Core.#current_scope#2491.jit")
  %Builtin_ret = call nonnull ptr %0(ptr nonnull @"jl_global#2492.jit", ptr null, i32 0)
  ret ptr %Builtin_ret
}
; Function Signature: bar()
define void @julia_bar_589() #0 {
top:
  %jlcallframe1 = alloca [2 x ptr], align 8
  %0 = call ptr @jl_get_builtin_fptr(ptr nonnull @"+Core.#throw_methoderror#591.jit")
  %jl_nothing = load ptr, ptr @jl_nothing, align 8
  store ptr @"jl_global#593.jit", ptr %jlcallframe1, align 8
  %1 = getelementptr inbounds ptr, ptr %jlcallframe1, i64 1
  store ptr %jl_nothing, ptr %1, align 8
  %Builtin_ret = call nonnull ptr %0(ptr nonnull @"jl_global#592.jit", ptr nonnull %jlcallframe1, i32 2)
  call void @llvm.trap()
  unreachable
}
```

After:
```llvm
; Function Signature: foo()
define nonnull ptr @julia_foo_713() #0 {
top:
  %thread_ptr = call ptr asm "movq %fs:0, $0", "=r"() #5
  %tls_ppgcstack = getelementptr inbounds i8, ptr %thread_ptr, i64 -8
  %tls_pgcstack = load ptr, ptr %tls_ppgcstack, align 8
  %current_scope = getelementptr inbounds i8, ptr %tls_pgcstack, i64 -72
  %0 = load ptr, ptr %current_scope, align 8
  ret ptr %0
}
; Function Signature: bar()
define void @julia_bar_1581() #0 {
top:
  %jlcallframe1 = alloca [2 x ptr], align 8
  %jl_nothing = load ptr, ptr @jl_nothing, align 8
  store ptr @"jl_global#1583.jit", ptr %jlcallframe1, align 8
  %0 = getelementptr inbounds ptr, ptr %jlcallframe1, i64 1
  store ptr %jl_nothing, ptr %0, align 8
  %jl_f_throw_methoderror_ret = call nonnull ptr @jl_f_throw_methoderror(ptr null, ptr nonnull %jlcallframe1, i32 2)
  call void @llvm.trap()
  unreachable
}
```

Author: topolarity

src/builtins.c

@@ -2444,7 +2444,7 @@ void jl_init_primitives(void) JL_GC_DISABLED
     add_builtin_func("finalizer", jl_f_finalizer);
     add_builtin_func("_compute_sparams", jl_f__compute_sparams);
     add_builtin_func("_svec_ref", jl_f__svec_ref);
-    add_builtin_func("current_scope", jl_f_current_scope);
+    jl_builtin_current_scope = add_builtin_func("current_scope", jl_f_current_scope);
     add_builtin_func("throw_methoderror", jl_f_throw_methoderror);
 
     // builtin types

src/codegen.cpp

@@ -1619,6 +1619,7 @@ static const auto &builtin_func_map() {
           { jl_f__call_in_world_addr,     new JuliaFunction<>{XSTR(jl_f__call_in_world), get_func_sig, get_func_attrs} },
           { jl_f__call_in_world_total_addr, new JuliaFunction<>{XSTR(jl_f__call_in_world_total), get_func_sig, get_func_attrs} },
           { jl_f_throw_addr,              new JuliaFunction<>{XSTR(jl_f_throw), get_func_sig, get_func_attrs} },
+          { jl_f_throw_methoderror_addr,  new JuliaFunction<>{XSTR(jl_f_throw_methoderror), get_func_sig, get_func_attrs} },
           { jl_f_tuple_addr,              jltuple_func },
           { jl_f_svec_addr,               new JuliaFunction<>{XSTR(jl_f_svec), get_func_sig, get_func_attrs} },
           { jl_f_applicable_addr,         new JuliaFunction<>{XSTR(jl_f_applicable), get_func_sig, get_func_attrs} },
@@ -1644,7 +1645,8 @@ static const auto &builtin_func_map() {
           { jl_f_donotdelete_addr,        new JuliaFunction<>{XSTR(jl_f_donotdelete), get_donotdelete_sig, get_donotdelete_func_attrs} },
           { jl_f_compilerbarrier_addr,    new JuliaFunction<>{XSTR(jl_f_compilerbarrier), get_func_sig, get_func_attrs} },
           { jl_f_finalizer_addr,          new JuliaFunction<>{XSTR(jl_f_finalizer), get_func_sig, get_func_attrs} },
-          { jl_f__svec_ref_addr,          new JuliaFunction<>{XSTR(jl_f__svec_ref), get_func_sig, get_func_attrs} }
+          { jl_f__svec_ref_addr,          new JuliaFunction<>{XSTR(jl_f__svec_ref), get_func_sig, get_func_attrs} },
+          { jl_f_current_scope_addr,      new JuliaFunction<>{XSTR(jl_f_current_scope), get_func_sig, get_func_attrs} },
         };
     return builtins;
 }
@@ -2117,6 +2119,7 @@ static jl_cgval_t emit_sparam(jl_codectx_t &ctx, size_t i);
 static Value *emit_condition(jl_codectx_t &ctx, const jl_cgval_t &condV, const Twine &msg);
 static Value *get_current_task(jl_codectx_t &ctx);
 static Value *get_current_ptls(jl_codectx_t &ctx);
+static Value *get_scope_field(jl_codectx_t &ctx);
 static Value *get_tls_world_age_field(jl_codectx_t &ctx);
 static void CreateTrap(IRBuilder<> &irbuilder, bool create_new_block = true);
 static CallInst *emit_jlcall(jl_codectx_t &ctx, FunctionCallee theFptr, Value *theF,
@@ -4944,6 +4947,14 @@ static bool emit_builtin_call(jl_codectx_t &ctx, jl_cgval_t *ret, jl_value_t *f,
         return true;
     }
 
+    else if (f == jl_builtin_current_scope && (nargs == 0)) {
+        jl_aliasinfo_t scope_ai = jl_aliasinfo_t::fromTBAA(ctx, ctx.tbaa().tbaa_gcframe);
+        Instruction *v = scope_ai.decorateInst(
+            ctx.builder.CreateAlignedLoad(ctx.types().T_prjlvalue, get_scope_field(ctx), ctx.types().alignof_ptr));
+        *ret = mark_julia_type(ctx, v, /*boxed*/ true, rt);
+        return true;
+    }
+
     else if (f == jl_builtin_donotdelete) {
         // For now we emit this as a vararg call to the builtin
         // (which doesn't look at the arguments). In the future,

src/staticdata.c

@@ -100,7 +100,7 @@ extern "C" {
 // TODO: put WeakRefs on the weak_refs list during deserialization
 // TODO: handle finalizers
 
-#define NUM_TAGS    192
+#define NUM_TAGS    193
 
 // An array of references that need to be restored from the sysimg
 // This is a manually constructed dual of the gvars array, which would be produced by codegen for Julia code, for C.
@@ -312,6 +312,7 @@ jl_value_t **const*const get_tags(void) {
         INSERT_TAG(jl_builtin_modifyglobal);
         INSERT_TAG(jl_builtin_replaceglobal);
         INSERT_TAG(jl_builtin_setglobalonce);
+        INSERT_TAG(jl_builtin_current_scope);
         // n.b. must update NUM_TAGS when you add something here
 #undef INSERT_TAG
         assert(i == NUM_TAGS - 1);