Combine call info and cache to speed up method invocation

To perform a regular method call, the VM needs two structs,
`rb_call_info` and `rb_call_cache`. At the moment, we allocate these two
structures in separate buffers. In the worst case, the CPU needs to read
4 cache lines to complete a method call. Putting the two structures
together reduces the maximum number of cache line reads to 2.

Combining the structures also saves 8 bytes per call site as the current
layout uses separate two pointers for the call info and the call cache.
This saves about 2 MiB on Discourse.

This change improves the Optcarrot benchmark at least 3%. For more
details, see attached bugs.ruby-lang.org ticket.

Complications:
 - A new instruction attribute `comptime_sp_inc` is introduced to
 calculate SP increase at compile time without using call caches. At
 compile time, a `TS_CALLDATA` operand points to a call info struct, but
 at runtime, the same operand points to a call data struct. Instruction
 that explicitly define `sp_inc` also need to define `comptime_sp_inc`.
 - MJIT code for copying call cache becomes slightly more complicated.
 - This changes the bytecode format, which might break existing tools.

[Misc #16258]

1 files changed, 10 insertions, 1 deletions

diff --git a/mjit.c b/mjit.c
index 3ae9410179..f1e3934326 100644
--- a/mjit.c
+++ b/mjit.c
@@ -46,7 +46,16 @@ mjit_copy_job_handler(void *data)
 
     const struct rb_iseq_constant_body *body = job->iseq->body;
     if (job->cc_entries) {
-        memcpy(job->cc_entries, body->cc_entries, sizeof(struct rb_call_cache) * (body->ci_size + body->ci_kw_size));
+        unsigned int i;
+        struct rb_call_cache *sink = job->cc_entries;
+        const struct rb_call_data *calls = body->call_data;
+        const struct rb_kwarg_call_data *kw_calls = (struct rb_kwarg_call_data *)&body->call_data[body->ci_size];
+        for (i = 0; i < body->ci_size; i++) {
+            *sink++ = calls[i].cc;
+        }
+        for (i = 0; i < body->ci_kw_size; i++) {
+            *sink++ = kw_calls[i].cc;
+        }
     }
     if (job->is_entries) {
         memcpy(job->is_entries, body->is_entries, sizeof(union iseq_inline_storage_entry) * body->is_size);