First cut of storing/looking things up in the SC. Will need something…

… for putting one assembled at compile time in place too.

build/Makefile.in

@@ -159,13 +159,14 @@ METAMODEL_SOURCE = src/metamodel/rakudoobject.h src/metamodel/rakudoobject.c \
                    src/metamodel/reprs/P6str.h src/metamodel/reprs/P6str.c \
                    src/metamodel/reprs/P6num.h src/metamodel/reprs/P6num.c \
                    src/metamodel/multi_dispatch.h src/metamodel/multi_dispatch.c \
-                   src/metamodel/storage_spec.h
+                   src/metamodel/storage_spec.h src/metamodel/serialization_context.c \
+                   src/metamodel/serialization_context.h
 
 METAMODEL_OBJS   = ../metamodel/rakudoobject$(O) ../metamodel/repr_registry$(O) \
                    ../metamodel/knowhow_bootstrapper$(O) ../metamodel/reprs/KnowHOWREPR$(O) \
                    ../metamodel/reprs/P6opaque$(O) ../metamodel/reprs/P6int$(O) \
                    ../metamodel/reprs/P6str$(O) ../metamodel/reprs/P6num$(O) \
-                   ../metamodel/multi_dispatch$(O)
+                   ../metamodel/multi_dispatch$(O) ../metamodel/serialization_context$(O)
 
 HOW_SOURCES  = src/metamodel/how/KnowHOWAttribute.pm src/metamodel/how/NQPClassHOW.pm \
                src/metamodel/how/NQPNativeHOW.pm src/metamodel/how/NQPAttribute.pm \
@@ -393,6 +394,7 @@ $(OPS_DIR)/$(OPS)$(LOAD_EXT): $(OPS_DIR)/$(OPS_SOURCE) $(DYNPMC)
 	cd src/metamodel/reprs && $(CC) -c @cc_o_out@P6str$(O) -I../../../$(PMC_DIR) $(CINCLUDES) $(CFLAGS) P6str.c
 	cd src/metamodel/reprs && $(CC) -c @cc_o_out@P6num$(O) -I../../../$(PMC_DIR) $(CINCLUDES) $(CFLAGS) P6num.c
 	cd src/metamodel && $(CC) -c @cc_o_out@multi_dispatch$(O) -I../../$(PMC_DIR) $(CINCLUDES) $(CFLAGS) multi_dispatch.c
+	cd src/metamodel && $(CC) -c @cc_o_out@serialization_context$(O) -I../../$(PMC_DIR) $(CINCLUDES) $(CFLAGS) serialization_context.c
 	cd $(OPS_DIR) && $(LD) @ld_out@$(OPS)$(LOAD_EXT) $(OPS)$(O) $(METAMODEL_OBJS) $(LINKARGS)
 
 bootstrap-files: $(STAGE2_PBCS) $(SETTING_NQP)

src/metamodel/serialization_context.c

@@ -0,0 +1,70 @@
+/* This implements a little bit of support for serialization contexts.
+ * At the moment, its main role is to let us have a PMC array of objects
+ * per Parrot bytecode segment. This gives fast access to them. Note
+ * that if this ever made it into core Parrot, we'd hang it off the
+ * packfile data structure, or maybe consider whether there's a kind of
+ * unification with the "constants" segment. */
+
+#define PARROT_IN_EXTENSION
+#include "parrot/parrot.h"
+#include "parrot/extend.h"
+
+/* Array of root object arrays, one per SC. */
+static PMC *sc_root_objects = NULL;
+
+/* Array of bytecode segment locations. Related to the above array.
+ * Just an array of integers. Can be array of bytecode PMCs later. */
+static PMC *sc_index_lookup = NULL;
+
+/* Initializes the stores and register them with the GC. */
+static void setup_sc_stores(PARROT_INTERP) {
+    sc_root_objects = pmc_new(interp, enum_class_ResizablePMCArray);
+    sc_index_lookup = pmc_new(interp, enum_class_ResizableIntegerArray);
+    Parrot_pmc_gc_register(interp, sc_root_objects);
+    Parrot_pmc_gc_register(interp, sc_index_lookup);
+}
+
+/* Gets an object from the serialization context associated with the
+ * current bytecode segment. */
+PMC * SC_get_sc_object(PARROT_INTERP, INTVAL idx) {
+    /* Locate the SC root list for this bytecode segment. */
+    INTVAL addr = (INTVAL)interp->code;
+    INTVAL scs  = VTABLE_elements(interp, sc_index_lookup);
+    INTVAL i;
+    for (i = 0; i < scs; i++) {
+        if (VTABLE_get_integer_keyed_int(interp, sc_index_lookup, i) == addr) {
+            /* Found it; grab object we're looking for. */
+            PMC *sc_root = VTABLE_get_pmc_keyed_int(interp, sc_root_objects, i);
+            return VTABLE_get_pmc_keyed_int(interp, sc_root, idx);
+        }
+    }
+
+    /* None found, just return PMCNULL. */
+    return PMCNULL;
+}
+
+/* Puts an object into the serialization context associated with the
+ * current bytecode segment. */
+void SC_set_sc_object(PARROT_INTERP, INTVAL idx, PMC *object) {
+    /* Locate the SC root list for this bytecode segment. */
+    INTVAL addr    = (INTVAL)interp->code;
+    INTVAL scs     = VTABLE_elements(interp, sc_index_lookup);
+    PMC *  sc_root = PMCNULL;
+    INTVAL i;
+    for (i = 0; i < scs; i++) {
+        if (VTABLE_get_integer_keyed_int(interp, sc_index_lookup, i) == addr) {
+            sc_root = VTABLE_get_pmc_keyed_int(interp, sc_root_objects, i);
+            break;
+        }
+    }
+
+    /* If we found none, add it. */
+    if (PMC_IS_NULL(sc_root)) {
+        sc_root = pmc_new(interp, enum_class_ResizablePMCArray);
+        VTABLE_set_pmc_keyed_int(interp, sc_root_objects, scs, sc_root);
+        VTABLE_set_integer_keyed_int(interp, sc_index_lookup, scs, addr);
+    }
+
+    /* Stash the value in the the SC. */
+    VTABLE_set_pmc_keyed_int(interp, sc_root, idx, object);
+}

src/metamodel/serialization_context.h

@@ -0,0 +1,7 @@
+#ifndef SERIALIZATIONCONTEXT_H_GUARD
+#define SERIALIZATIONCONTEXT_H_GUARD
+
+PMC * SC_get_sc_object(PARROT_INTERP, INTVAL idx);
+void SC_set_sc_object(PARROT_INTERP, INTVAL idx, PMC *object);
+
+#endif

src/ops/nqp.ops

@@ -11,6 +11,7 @@ BEGIN_OPS_PREAMBLE
 #include "../pmc/pmc_dispatchersub.h"
 #include "../pmc/pmc_nqpmultisig.h"
 #include "../metamodel/multi_dispatch.h"
+#include "../metamodel/serialization_context.h"
 #include "pmc_sub.h"
 
 /* Did we do the dynop setup yet?
@@ -636,3 +637,29 @@ inline op stable_publish_vtable_mapping(in PMC, in PMC) :base_core {
         Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
             "Can only use stable_publish_vtable_mapping with a RakudoObject");
 }
+
+/*
+
+=item nqp_get_sc_object()
+
+Fetches an object from the current segment's serialization context.
+
+=cut
+
+*/
+inline op nqp_get_sc_object(out PMC, in INT) :base_core {
+    $1 = SC_get_sc_object(interp, $2);
+}
+
+/*
+
+=item nqp_set_sc_object()
+
+Stores an object in the current segment's serialization context.
+
+=cut
+
+*/
+inline op nqp_set_sc_object(in INT, in PMC) :base_core {
+    SC_set_sc_object(interp, $1, $2);
+}