YJIT: Fallback megamorphic opt_case_dispatch (#9894)

ruby · Feb 9, 2024 · 717adb5 · 717adb5
1 parent 80490ac
commit 717adb5
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Showing 3 changed files with 11 additions and 3 deletions.
diff --git a/yjit.rb b/yjit.rb
@@ -323,8 +323,9 @@ def _print_stats(out: $stderr) # :nodoc:
         out.puts "num_send_x86_rel32:    " + format_number(13,  stats[:num_send_x86_rel32])
         out.puts "num_send_x86_reg:      " + format_number(13, stats[:num_send_x86_reg])
       end
-      out.puts "num_getivar_megamorphic: " + format_number(13, stats[:num_getivar_megamorphic])
-      out.puts "num_setivar_megamorphic: " + format_number(13, stats[:num_setivar_megamorphic])
+      out.puts "num_getivar_megamorphic: " + format_number(11, stats[:num_getivar_megamorphic])
+      out.puts "num_setivar_megamorphic: " + format_number(11, stats[:num_setivar_megamorphic])
+      out.puts "num_opt_case_megamorphic: " + format_number(10, stats[:num_opt_case_dispatch_megamorphic])
       out.puts "num_throw:             " + format_number(13, stats[:num_throw])
       out.puts "num_throw_break:       " + format_number_pct(13, stats[:num_throw_break], stats[:num_throw])
       out.puts "num_throw_retry:       " + format_number_pct(13, stats[:num_throw_retry], stats[:num_throw])

diff --git a/yjit/src/codegen.rs b/yjit/src/codegen.rs
@@ -4037,7 +4037,13 @@ fn gen_opt_case_dispatch(
         all_fixnum
     }
 
-    if comptime_key.fixnum_p() && comptime_key.0 <= u32::MAX.as_usize() && case_hash_all_fixnum_p(case_hash) {
+    // If megamorphic, fallback to compiling branch instructions after opt_case_dispatch
+    let megamorphic = asm.ctx.get_chain_depth() >= CASE_WHEN_MAX_DEPTH;
+    if megamorphic {
+        gen_counter_incr(asm, Counter::num_opt_case_dispatch_megamorphic);
+    }
+
+    if comptime_key.fixnum_p() && comptime_key.0 <= u32::MAX.as_usize() && case_hash_all_fixnum_p(case_hash) && !megamorphic {
         if !assume_bop_not_redefined(jit, asm, ocb, INTEGER_REDEFINED_OP_FLAG, BOP_EQQ) {
             return None;
         }

diff --git a/yjit/src/stats.rs b/yjit/src/stats.rs
@@ -592,6 +592,7 @@ make_counters! {
 
     num_getivar_megamorphic,
     num_setivar_megamorphic,
+    num_opt_case_dispatch_megamorphic,
 
     num_throw,
     num_throw_break,