https://git.ruby-lang.org/ruby.git/commit/?id=8c68f112d8

From 8c68f112d8ec9f5a9a416fc69602855bf43c4dd6 Mon Sep 17 00:00:00 2001
From: Alan Wu <XrXr@u...>
Date: Wed, 16 Jun 2021 16:55:13 -0400
Subject: Delay and be selective about when to discard local types

jit_rb_obj_not() wants to access the type information of the receiver,
but we were discarding type info of locals before jit_rb_obj_not() runs
unncessarily.

There are also cases we are unncessarily discarding local type info. For
example, ivar reader and setter methods can never change local
variables.
---
 yjit_codegen.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/yjit_codegen.c b/yjit_codegen.c
index b0973cb2a7..3a6f6c5cdc 100644
--- a/yjit_codegen.c
+++ b/yjit_codegen.c
@@ -2503,6 +2503,9 @@ gen_send_cfunc(jitstate_t *jit, ctx_t *ctx, const struct rb_callinfo *ci, const https://github.com/ruby/ruby/blob/trunk/yjit_codegen.c#L2503
         imm_opnd(sizeof(rb_control_frame_t))
     );
 
+    // cfunc calls may corrupt types
+    ctx_clear_local_types(ctx);
+
     // Note: gen_oswb_iseq() jumps to the next instruction with ctx->sp_offset == 0
     // after the call, while this does not. This difference prevents
     // the two call types from sharing the same successor.
@@ -2670,6 +2673,9 @@ gen_send_iseq(jitstate_t *jit, ctx_t *ctx, const struct rb_callinfo *ci, const r https://github.com/ruby/ruby/blob/trunk/yjit_codegen.c#L2673
         x86opnd_t stack_ret = ctx_stack_push(ctx, TYPE_UNKNOWN);
         mov(cb, stack_ret, RAX);
 
+        // Note: assuming that the leaf builtin doesn't change local variables here.
+        // Seems like a safe assumption.
+
         return YJIT_KEEP_COMPILING;
     }
 
@@ -2770,6 +2776,9 @@ gen_send_iseq(jitstate_t *jit, ctx_t *ctx, const struct rb_callinfo *ci, const r https://github.com/ruby/ruby/blob/trunk/yjit_codegen.c#L2776
     val_type_t recv_type = ctx_get_opnd_type(ctx, OPND_STACK(argc));
     ctx_set_opnd_type(&callee_ctx, OPND_SELF, recv_type);
 
+    // The callee might change locals through Kernel#binding and other means.
+    ctx_clear_local_types(ctx);
+
     // Pop arguments and receiver in return context, push the return value
     // After the return, the JIT and interpreter SP will match up
     ctx_t return_ctx = *ctx;
@@ -2889,9 +2898,6 @@ gen_send_general(jitstate_t *jit, ctx_t *ctx, struct rb_call_data *cd, rb_iseq_t https://github.com/ruby/ruby/blob/trunk/yjit_codegen.c#L2898
     RUBY_ASSERT(cme->called_id == mid);
     assume_method_lookup_stable(comptime_recv_klass, cme, jit->block);
 
-    // Method calls may corrupt types
-    ctx_clear_local_types(ctx);
-
     // To handle the aliased method case (VM_METHOD_TYPE_ALIAS)
     while (true) {
         // switch on the method type
-- 
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