Skip writing jit_return on exits

Author: k0kubun

vm.c

@@ -585,6 +585,7 @@ jit_exec(rb_execution_context_t *ec)
             // This is done here (once per JIT entry) instead of in each side exit
             // to reduce generated code size.
             if (UNDEF_P(result)) {
+                ec->cfp->jit_return = 0;
                 zjit_materialize_frames(ec->cfp);
             }
             return result;

vm_exec.h

@@ -189,7 +189,10 @@ default:                        \
             rb_jit_func_t func = zjit_compile(ec); \
             if (func) { \
                 val = zjit_entry(ec, ec->cfp, func); \
-                if (UNDEF_P(val)) zjit_materialize_frames(ec->cfp); \
+                if (UNDEF_P(val)) { \
+                    ec->cfp->jit_return = 0; \
+                    zjit_materialize_frames(ec->cfp); \
+                } \
             } \
         } \
     } \

zjit/src/backend/lir.rs

@@ -6,7 +6,7 @@ use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 use crate::bitset::BitSet;
 use crate::codegen::{local_size_and_idx_to_ep_offset, perf_symbol_range_start, perf_symbol_range_end};
-use crate::cruby::{CfpPtr, IseqPtr, Qundef, RUBY_OFFSET_CFP_ISEQ, RUBY_OFFSET_CFP_JIT_RETURN, RUBY_OFFSET_CFP_PC, RUBY_OFFSET_CFP_SP, SIZEOF_VALUE_I32, vm_stack_canary};
+use crate::cruby::{IseqPtr, Qundef, RUBY_OFFSET_CFP_ISEQ, RUBY_OFFSET_CFP_PC, RUBY_OFFSET_CFP_SP, SIZEOF_VALUE_I32, vm_stack_canary};
 use crate::hir::{Invariant, SideExitReason};
 use crate::hir;
 use crate::options::{TraceExits, PerfMap, get_option};
@@ -2639,8 +2639,8 @@ impl Assembler
             asm_comment!(asm, "save cfp->iseq");
             asm.store(Opnd::mem(64, CFP, RUBY_OFFSET_CFP_ISEQ), VALUE::from(*iseq).into());
 
-            asm_comment!(asm, "save cfp->jit_return");
-            asm.store(Opnd::mem(64, CFP, RUBY_OFFSET_CFP_JIT_RETURN), 0.into());
+            //asm_comment!(asm, "save cfp->jit_return");
+            //asm.store(Opnd::mem(64, CFP, RUBY_OFFSET_CFP_JIT_RETURN), 0.into());
         }
 
         /// Tear down the JIT frame and return to the interpreter.