struct: avoid all O(n) behavior on access

This avoids O(n) on lookups with structs over 10 members.
This also avoids O(n) behavior on all assignments on Struct members.
Members 0..9 still use existing C methods to read in O(1) time

Benchmark results:

vm2_struct_big_aref_hi*	1.305
vm2_struct_big_aref_lo*	1.157
vm2_struct_big_aset*	3.306
vm2_struct_small_aref*	1.015
vm2_struct_small_aset*	3.273

Note: I chose use loading instructions from an array instead of writing
directly to linked-lists in compile.c for ease-of-maintainability.  We
may move the method definitions to prelude.rb-like files in the future.

I have also tested this patch with the following patch to disable
the C ref_func methods and ensured the test suite and rubyspec works

	--- a/struct.c
	+++ b/struct.c
	@@ -209,7 +209,7 @@ setup_struct(VALUE nstr, VALUE members)
		ID id = SYM2ID(ptr_members[i]);
		VALUE off = LONG2NUM(i);

	-	if (i < N_REF_FUNC) {
	+	if (0 && i < N_REF_FUNC) {
		    rb_define_method_id(nstr, id, ref_func[i], 0);
		}
		else {

* iseq.c (rb_method_for_self_aref, rb_method_for_self_aset):
  new methods to generate bytecode for struct.c
  [Feature #10575]
* struct.c (rb_struct_ref, rb_struct_set): remove
  (define_aref_method, define_aset_method): new functions
  (setup_struct): use new functions
* test/ruby/test_struct.rb: add test for struct >10 members
* benchmark/bm_vm2_struct_big_aref_hi.rb: new benchmark
* benchmark/bm_vm2_struct_big_aref_lo.rb: ditto
* benchmark/bm_vm2_struct_big_aset.rb: ditto
* benchmark/bm_vm2_struct_small_aref.rb: ditto
* benchmark/bm_vm2_struct_small_aset.rb: ditto

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48748 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

9 files changed, 187 insertions, 34 deletions

diff --git a/ChangeLog b/ChangeLog
index bb994480e9..5fd9cb8755 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+Wed Dec 10 00:42:13 2014  Eric Wong  <e@80x24.org>
+
+	* iseq.c (rb_method_for_self_aref, rb_method_for_self_aset):
+	  new methods to generate bytecode for struct.c
+	  [Feature #10575]
+	* struct.c (rb_struct_ref, rb_struct_set): remove
+	  (define_aref_method, define_aset_method): new functions
+	  (setup_struct): use new functions
+	* test/ruby/test_struct.rb: add test for struct >10 members
+	* benchmark/bm_vm2_struct_big_aref_hi.rb: new benchmark
+	* benchmark/bm_vm2_struct_big_aref_lo.rb: ditto
+	* benchmark/bm_vm2_struct_big_aset.rb: ditto
+	* benchmark/bm_vm2_struct_small_aref.rb: ditto
+	* benchmark/bm_vm2_struct_small_aset.rb: ditto
+
 Tue Dec  9 20:24:41 2014  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
 
 	* string.c: [DOC] Add missing documentation around String#chomp.
diff --git a/benchmark/bm_vm2_struct_big_aref_hi.rb b/benchmark/bm_vm2_struct_big_aref_hi.rb
new file mode 100644
index 0000000000..22cb26b0a5
--- /dev/null
+++ b/benchmark/bm_vm2_struct_big_aref_hi.rb
@@ -0,0 +1,7 @@
+s = Struct.new(*('a'..'z').map { |x| x.to_sym })
+x = s.new
+i = 0
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  x.z # x[25]
+end
diff --git a/benchmark/bm_vm2_struct_big_aref_lo.rb b/benchmark/bm_vm2_struct_big_aref_lo.rb
new file mode 100644
index 0000000000..5e61a7087e
--- /dev/null
+++ b/benchmark/bm_vm2_struct_big_aref_lo.rb
@@ -0,0 +1,7 @@
+s = Struct.new(*('a'..'z').map { |x| x.to_sym })
+x = s.new
+i = 0
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  x.k # x[10]
+end
diff --git a/benchmark/bm_vm2_struct_big_aset.rb b/benchmark/bm_vm2_struct_big_aset.rb
new file mode 100644
index 0000000000..5a1c3d16f3
--- /dev/null
+++ b/benchmark/bm_vm2_struct_big_aset.rb
@@ -0,0 +1,7 @@
+s = Struct.new(*('a'..'z').map { |x| x.to_sym })
+x = s.new
+i = 0
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  x.k = i # x[10] = i
+end
diff --git a/benchmark/bm_vm2_struct_small_aref.rb b/benchmark/bm_vm2_struct_small_aref.rb
new file mode 100644
index 0000000000..8eaa555b41
--- /dev/null
+++ b/benchmark/bm_vm2_struct_small_aref.rb
@@ -0,0 +1,7 @@
+s = Struct.new(:a, :b, :c)
+x = s.new
+i = 0
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  x.a
+end
diff --git a/benchmark/bm_vm2_struct_small_aset.rb b/benchmark/bm_vm2_struct_small_aset.rb
new file mode 100644
index 0000000000..ecd0f95669
--- /dev/null
+++ b/benchmark/bm_vm2_struct_small_aset.rb
@@ -0,0 +1,7 @@
+s = Struct.new(:a, :b, :c)
+x = s.new
+i = 0
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  x.a = i
+end
diff --git a/iseq.c b/iseq.c
index 8f84f88c14..15d1de698c 100644
--- a/iseq.c
+++ b/iseq.c
@@ -548,6 +548,107 @@ iseq_load(VALUE self, VALUE data, VALUE parent, VALUE opt)
     return iseqval;
 }
 
+rb_iseq_t *
+rb_method_for_self_aref(VALUE name, VALUE arg)
+{
+    VALUE iseqval = iseq_alloc(rb_cISeq);
+    rb_iseq_t *iseq;
+    VALUE path = rb_str_new2("<compiled>");
+    VALUE lineno = INT2FIX(1);
+    VALUE parent = 0;
+    VALUE misc, locals, params, exception, body, send_arg;
+    int flag = VM_CALL_FCALL | VM_CALL_ARGS_SIMPLE;
+
+    GetISeqPtr(iseqval, iseq);
+    iseq->self = iseqval;
+    iseq->local_iseq = iseq;
+
+    prepare_iseq_build(iseq, rb_sym2str(name), path, path, lineno, parent,
+		       ISEQ_TYPE_METHOD, &COMPILE_OPTION_DEFAULT);
+
+    misc = params = rb_hash_new(); /* empty */
+    locals = exception = rb_ary_new(); /* empty */
+    body = rb_ary_new();
+
+#define S(s) ID2SYM(rb_intern(#s))
+    /* def name; self[arg]; end */
+    rb_ary_push(body, lineno);
+    rb_ary_push(body, rb_ary_new3(1, S(putself)));
+    rb_ary_push(body, rb_ary_new3(2, S(putobject), arg));
+
+    /* {:mid=>:[], :flag=>264, :blockptr=>nil, :orig_argc=>1} */
+    send_arg = rb_hash_new();
+    rb_hash_aset(send_arg, S(mid), ID2SYM(idAREF));
+    rb_hash_aset(send_arg, S(flag), INT2FIX(flag));
+    rb_hash_aset(send_arg, S(blockptr), Qnil);
+    rb_hash_aset(send_arg, S(orig_argc), INT2FIX(1));
+
+    /* we do not want opt_aref for struct */
+    rb_ary_push(body, rb_ary_new3(2, S(opt_send_without_block), send_arg));
+    rb_ary_push(body, rb_ary_new3(1, S(leave)));
+#undef S
+
+    rb_iseq_build_from_ary(iseq, misc, locals, params, exception, body);
+    cleanup_iseq_build(iseq);
+
+    return iseq;
+}
+
+rb_iseq_t *
+rb_method_for_self_aset(VALUE name, VALUE arg)
+{
+    VALUE iseqval = iseq_alloc(rb_cISeq);
+    rb_iseq_t *iseq;
+    VALUE path = rb_str_new2("<compiled>");
+    VALUE lineno = INT2FIX(1);
+    VALUE parent = 0;
+    VALUE misc, locals, params, exception, body, send_arg;
+    int flag = VM_CALL_FCALL | VM_CALL_ARGS_SIMPLE;
+
+    GetISeqPtr(iseqval, iseq);
+    iseq->self = iseqval;
+    iseq->local_iseq = iseq;
+
+    prepare_iseq_build(iseq, rb_sym2str(name), path, path, lineno, parent,
+		       ISEQ_TYPE_METHOD, &COMPILE_OPTION_DEFAULT);
+
+    /* def name=(val); self[arg] = val; end */
+#define S(s) ID2SYM(rb_intern(#s))
+    misc = rb_hash_new(); /* empty */
+    locals = rb_ary_new3(1, S(val));
+    params = rb_hash_new();
+    exception = rb_ary_new(); /* empty */
+    body = rb_ary_new();
+
+    rb_hash_aset(params, S(lead_num), INT2FIX(1));
+
+    rb_ary_push(body, lineno);
+    rb_ary_push(body, rb_ary_new3(1, S(putnil)));
+    rb_ary_push(body, rb_ary_new3(1, S(putself)));
+    rb_ary_push(body, rb_ary_new3(2, S(putobject), arg));
+    rb_ary_push(body, rb_ary_new3(3, S(getlocal), INT2FIX(2), INT2FIX(0)));
+    rb_ary_push(body, rb_ary_new3(2, S(setn), INT2FIX(3)));
+
+    /* {:mid=>:[]=, :flag=>264, :blockptr=>nil, :orig_argc=>2} */
+    send_arg = rb_hash_new();
+    rb_hash_aset(send_arg, S(mid), ID2SYM(idASET));
+    rb_hash_aset(send_arg, S(flag), INT2FIX(flag));
+    rb_hash_aset(send_arg, S(blockptr), Qnil);
+    rb_hash_aset(send_arg, S(orig_argc), INT2FIX(2));
+
+    /* we do not want opt_aset for struct */
+    rb_ary_push(body, rb_ary_new3(2, S(opt_send_without_block), send_arg));
+
+    rb_ary_push(body, rb_ary_new3(1, S(pop)));
+    rb_ary_push(body, rb_ary_new3(1, S(leave)));
+#undef S
+
+    rb_iseq_build_from_ary(iseq, misc, locals, params, exception, body);
+    cleanup_iseq_build(iseq);
+
+    return iseq;
+}
+
 /*
  * :nodoc:
  */
diff --git a/struct.c b/struct.c
index 93c55999c0..3a2ea47434 100644
--- a/struct.c
+++ b/struct.c
@@ -10,6 +10,11 @@
 **********************************************************************/
 
 #include "internal.h"
+#include "vm_core.h"
+#include "method.h"
+
+rb_iseq_t *rb_method_for_self_aref(VALUE name, VALUE arg);
+rb_iseq_t *rb_method_for_self_aset(VALUE name, VALUE arg);
 
 VALUE rb_cStruct;
 static ID id_members;
@@ -105,12 +110,6 @@ rb_struct_getmember(VALUE obj, ID id)
     UNREACHABLE;
 }
 
-static VALUE
-rb_struct_ref(VALUE obj)
-{
-    return rb_struct_getmember(obj, rb_frame_this_func());
-}
-
 static VALUE rb_struct_ref0(VALUE obj) {return RSTRUCT_GET(obj, 0);}
 static VALUE rb_struct_ref1(VALUE obj) {return RSTRUCT_GET(obj, 1);}
 static VALUE rb_struct_ref2(VALUE obj) {return RSTRUCT_GET(obj, 2);}
@@ -145,32 +144,6 @@ rb_struct_modify(VALUE s)
 }
 
 static VALUE
-rb_struct_set(VALUE obj, VALUE val)
-{
-    VALUE members, slot, fsym;
-    long i, len;
-    ID fid = rb_frame_this_func();
-    ID this_func = fid;
-
-    members = rb_struct_members(obj);
-    len = RARRAY_LEN(members);
-    rb_struct_modify(obj);
-    fid = rb_id_attrget(fid);
-    if (!fid) not_a_member(this_func);
-    fsym = ID2SYM(fid);
-    for (i=0; i<len; i++) {
-	slot = RARRAY_AREF(members, i);
-	if (slot == fsym) {
-	    RSTRUCT_SET(obj, i, val);
-	    return val;
-	}
-    }
-    not_a_member(fid);
-
-    UNREACHABLE;
-}
-
-static VALUE
 anonymous_struct(VALUE klass)
 {
     VALUE nstr;
@@ -199,6 +172,24 @@ new_struct(VALUE name, VALUE super)
     return rb_define_class_id_under(super, id, super);
 }
 
+static void
+define_aref_method(VALUE nstr, VALUE name, VALUE off)
+{
+    rb_iseq_t *iseq = rb_method_for_self_aref(name, off);
+
+    rb_add_method(nstr, SYM2ID(name), VM_METHOD_TYPE_ISEQ, iseq, NOEX_PUBLIC);
+    RB_GC_GUARD(iseq->self);
+}
+
+static void
+define_aset_method(VALUE nstr, VALUE name, VALUE off)
+{
+    rb_iseq_t *iseq = rb_method_for_self_aset(name, off);
+
+    rb_add_method(nstr, SYM2ID(name), VM_METHOD_TYPE_ISEQ, iseq, NOEX_PUBLIC);
+    RB_GC_GUARD(iseq->self);
+}
+
 static VALUE
 setup_struct(VALUE nstr, VALUE members)
 {
@@ -216,13 +207,15 @@ setup_struct(VALUE nstr, VALUE members)
     len = RARRAY_LEN(members);
     for (i=0; i< len; i++) {
 	ID id = SYM2ID(ptr_members[i]);
+	VALUE off = LONG2NUM(i);
+
 	if (i < N_REF_FUNC) {
 	    rb_define_method_id(nstr, id, ref_func[i], 0);
 	}
 	else {
-	    rb_define_method_id(nstr, id, rb_struct_ref, 0);
+	    define_aref_method(nstr, ptr_members[i], off);
 	}
-	rb_define_method_id(nstr, rb_id_attrset(id), rb_struct_set, 1);
+	define_aset_method(nstr, ID2SYM(rb_id_attrset(id)), off);
     }
 
     return nstr;
diff --git a/test/ruby/test_struct.rb b/test/ruby/test_struct.rb
index 71d93fb09d..8307d7932e 100644
--- a/test/ruby/test_struct.rb
+++ b/test/ruby/test_struct.rb
@@ -186,6 +186,15 @@ module TestStruct
     assert_raise(ArgumentError) { o.select(1) }
   end
 
+  def test_big_struct
+    klass1 = @Struct.new(*('a'..'z').map(&:to_sym))
+    o = klass1.new
+    assert_nil o.z
+    assert_equal(:foo, o.z = :foo)
+    assert_equal(:foo, o.z)
+    assert_equal(:foo, o[25])
+  end
+
   def test_equal
     klass1 = @Struct.new(:a)
     klass2 = @Struct.new(:a, :b)