Introduce BOP_CMP for optimized comparison

Prior to this commit the `OPTIMIZED_CMP` macro relied on a method lookup
to determine whether `<=>` was overridden. The result of the lookup was
cached, but only for the duration of the specific method that
initialized the cmp_opt_data cache structure.

With this method lookup, `[x,y].max` is slower than doing `x > y ?
x : y` even though there's an optimized instruction for "new array max".
(John noticed somebody a proposed micro-optimization based on this fact
in https://github.com/mastodon/mastodon/pull/19903.)

```rb
a, b = 1, 2
Benchmark.ips do |bm|
  bm.report('conditional') { a > b ? a : b }
  bm.report('method') { [a, b].max }
  bm.compare!
end
```

Before:

```
Comparison:
         conditional: 22603733.2 i/s
              method: 19820412.7 i/s - 1.14x  (± 0.00) slower
```

This commit replaces the method lookup with a new CMP basic op, which
gives the examples above equivalent performance.

After:

```
Comparison:
              method: 24022466.5 i/s
         conditional: 23851094.2 i/s - same-ish: difference falls within
error
```

Relevant benchmarks show an improvement to Array#max and Array#min when
not using the optimized newarray_max instruction as well. They are
noticeably faster for small arrays with the relevant types, and the same
or maybe a touch faster on larger arrays.

```
$ make benchmark COMPARE_RUBY=<master@5958c305> ITEM=array_min
$ make benchmark COMPARE_RUBY=<master@5958c305> ITEM=array_max
```

The benchmarks added in this commit also look generally improved.

Co-authored-by: John Hawthorn <jhawthorn@github.com>

1 files changed, 6 insertions, 26 deletions

diff --git a/internal/compar.h b/internal/compar.h
index 5e336adafa..9115e4bd63 100644
--- a/internal/compar.h
+++ b/internal/compar.h
@@ -8,38 +8,18 @@
  *             file COPYING are met.  Consult the file for details.
  * @brief      Internal header for Comparable.
  */
-#include "internal/vm.h"        /* for rb_method_basic_definition_p */
+#include "internal/basic_operators.h"
 
 #define STRING_P(s) (RB_TYPE_P((s), T_STRING) && CLASS_OF(s) == rb_cString)
 
-enum {
-    cmp_opt_Integer,
-    cmp_opt_String,
-    cmp_opt_Float,
-    cmp_optimizable_count
-};
+#define CMP_OPTIMIZABLE(type) BASIC_OP_UNREDEFINED_P(BOP_CMP, type##_REDEFINED_OP_FLAG)
 
-struct cmp_opt_data {
-    unsigned int opt_methods;
-    unsigned int opt_inited;
-};
-
-#define NEW_CMP_OPT_MEMO(type, value) \
-    NEW_PARTIAL_MEMO_FOR(type, value, cmp_opt)
-#define CMP_OPTIMIZABLE_BIT(type) (1U << TOKEN_PASTE(cmp_opt_,type))
-#define CMP_OPTIMIZABLE(data, type) \
-    (((data).opt_inited & CMP_OPTIMIZABLE_BIT(type)) ? \
-     ((data).opt_methods & CMP_OPTIMIZABLE_BIT(type)) : \
-     (((data).opt_inited |= CMP_OPTIMIZABLE_BIT(type)), \
-      rb_method_basic_definition_p(TOKEN_PASTE(rb_c,type), id_cmp) && \
-      ((data).opt_methods |= CMP_OPTIMIZABLE_BIT(type))))
-
-#define OPTIMIZED_CMP(a, b, data) \
-    ((FIXNUM_P(a) && FIXNUM_P(b) && CMP_OPTIMIZABLE(data, Integer)) ? \
+#define OPTIMIZED_CMP(a, b) \
+    ((FIXNUM_P(a) && FIXNUM_P(b) && CMP_OPTIMIZABLE(INTEGER)) ? \
      (((long)a > (long)b) ? 1 : ((long)a < (long)b) ? -1 : 0) : \
-     (STRING_P(a) && STRING_P(b) && CMP_OPTIMIZABLE(data, String)) ? \
+     (STRING_P(a) && STRING_P(b) && CMP_OPTIMIZABLE(STRING)) ? \
      rb_str_cmp(a, b) : \
-     (RB_FLOAT_TYPE_P(a) && RB_FLOAT_TYPE_P(b) && CMP_OPTIMIZABLE(data, Float)) ? \
+     (RB_FLOAT_TYPE_P(a) && RB_FLOAT_TYPE_P(b) && CMP_OPTIMIZABLE(FLOAT)) ? \
      rb_float_cmp(a, b) : \
      rb_cmpint(rb_funcallv(a, id_cmp, 1, &b), a, b))