Feature #10575

Updated by nobu (Nobuyoshi Nakada) almost 8 years ago

 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` 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 {