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matzclaude
matz
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claude
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variable.c: add object shapes for MRB_TT_OBJECT IV storage
Introduce "object shapes" (hidden classes) that share IV key layouts across objects with the same instance variable assignment order. This eliminates per-object key storage overhead. Memory savings: ~22% heap reduction for object-heavy workloads (e.g., 150k objects with 2-6 IVs). Per-object: 40->24 bytes for 2 IVs. Objects exceeding 16 IVs or using remove_instance_variable fall back to traditional iv_tbl. Co-authored-by: Claude <noreply@anthropic.com>
1 parent b4d2524 commit 8d10056

6 files changed

Lines changed: 403 additions & 12 deletions

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‎include/mruby.h‎

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@@ -325,6 +325,8 @@ typedef struct mrb_state {
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struct mrb_mt_rom_list *rom_mt; /* heap-allocated ROM wrappers (freed at close) */
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struct mrb_iv_shape *root_shape; /* root of IV shape tree */
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void *ud; /* auxiliary data */
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#ifdef MRB_FIXED_STATE_ATEXIT_STACK

‎include/mruby/internal.h‎

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@@ -199,6 +199,10 @@ void mrb_gc_free_gv(mrb_state*);
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size_t mrb_gc_mark_iv(mrb_state*, struct RObject*);
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void mrb_gc_free_iv(mrb_state*, struct RObject*);
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/* IV shape tree */
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void mrb_init_shape(mrb_state*);
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void mrb_free_shape(mrb_state*);
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/* VM */
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#define MRB_CI_VISIBILITY(ci) MRB_FLAGS_GET((ci)->vis, 0, 2)
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#define MRB_CI_SET_VISIBILITY(ci, visi) MRB_FLAGS_SET((ci)->vis, 0, 2, visi)

‎include/mruby/object.h‎

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@@ -24,6 +24,11 @@ struct RBasic {
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#define MRB_OBJ_IS_FROZEN 1
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#define mrb_frozen_p(o) ((o)->frozen)
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/* Object shape flag -- when set, obj->iv is shaped, not iv_tbl* */
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/* Bit 5: avoids conflict with MRB_INSTANCE_TT_MASK (bits 0-4) */
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#define MRB_FL_OBJ_SHAPED (1 << 5)
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#define MRB_OBJ_SHAPED_P(o) ((o)->flags & MRB_FL_OBJ_SHAPED)
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struct RObject {
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MRB_OBJECT_HEADER;
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struct iv_tbl *iv;

‎src/gc.c‎

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@@ -601,6 +601,9 @@ mrb_obj_alloc(mrb_state *mrb, enum mrb_vtype ttype, struct RClass *cls)
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*p = RVALUE_zero;
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p->as.basic.tt = ttype;
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p->as.basic.c = cls;
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if (ttype == MRB_TT_OBJECT) {
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p->as.basic.flags |= MRB_FL_OBJ_SHAPED;
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}
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paint_partial_white(gc, &p->as.basic);
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return &p->as.basic;
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}

‎src/state.c‎

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@@ -22,12 +22,16 @@ void mrb_gc_destroy(mrb_state*, mrb_gc *gc);
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int mrb_core_init_protect(mrb_state *mrb, void (*body)(mrb_state*, void*), void *opaque);
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void mrb_init_shape(mrb_state*);
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void mrb_free_shape(mrb_state*);
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static void
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init_gc_and_core(mrb_state *mrb, void *opaque)
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{
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static const struct mrb_context mrb_context_zero = { 0 };
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mrb_gc_init(mrb, &mrb->gc);
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mrb_init_shape(mrb);
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mrb->c = (struct mrb_context*)mrb_malloc(mrb, sizeof(struct mrb_context));
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*mrb->c = mrb_context_zero;
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mrb->root_c = mrb->c;
@@ -187,6 +191,7 @@ mrb_close(mrb_state *mrb)
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/* free */
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mrb_gc_free_gv(mrb);
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mrb_gc_destroy(mrb, &mrb->gc);
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mrb_free_shape(mrb);
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mrb_free_context(mrb, mrb->root_c);
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mrb_free_symtbl(mrb);
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