From d690e8327644102386deeaeee8eb4818c24fd38b Mon Sep 17 00:00:00 2001
From: Max Bernstein <ruby@bernsteinbear.com>
Date: Thu, 21 Aug 2025 16:22:26 -0400
Subject: ZJIT: Add CheckInterrupts HIR instruction

---
 zjit/src/codegen.rs | 12 ++++++++++++
 zjit/src/hir.rs     | 14 ++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/zjit/src/codegen.rs b/zjit/src/codegen.rs
index 0549365666..16d44c74b0 100644
--- a/zjit/src/codegen.rs
+++ b/zjit/src/codegen.rs
@@ -395,6 +395,7 @@ fn gen_insn(cb: &mut CodeBlock, jit: &mut JITState, asm: &mut Assembler, functio
         Insn::GetSpecialNumber { nth, state } => gen_getspecial_number(asm, *nth, &function.frame_state(*state)),
         &Insn::IncrCounter(counter) => no_output!(gen_incr_counter(asm, counter)),
         Insn::ObjToString { val, cd, state, .. } => gen_objtostring(jit, asm, opnd!(val), *cd, &function.frame_state(*state)),
+        &Insn::CheckInterrupts { state } => no_output!(gen_check_interrupts(jit, asm, &function.frame_state(state))),
         Insn::ArrayExtend { .. }
         | Insn::ArrayMax { .. }
         | Insn::ArrayPush { .. }
@@ -674,6 +675,17 @@ fn gen_getspecial_number(asm: &mut Assembler, nth: u64, state: &FrameState) -> O
     asm_ccall!(asm, rb_reg_nth_match, Opnd::Imm((nth >> 1).try_into().unwrap()), backref)
 }
 
+fn gen_check_interrupts(jit: &mut JITState, asm: &mut Assembler, state: &FrameState) {
+    // Check for interrupts
+    // see RUBY_VM_CHECK_INTS(ec) macro
+    asm_comment!(asm, "RUBY_VM_CHECK_INTS(ec)");
+    // Not checking interrupt_mask since it's zero outside finalize_deferred_heap_pages,
+    // signal_exec, or rb_postponed_job_flush.
+    let interrupt_flag = asm.load(Opnd::mem(32, EC, RUBY_OFFSET_EC_INTERRUPT_FLAG));
+    asm.test(interrupt_flag, interrupt_flag);
+    asm.jnz(side_exit(jit, state, SideExitReason::Interrupt));
+}
+
 /// Compile an interpreter entry block to be inserted into an ISEQ
 fn gen_entry_prologue(asm: &mut Assembler, iseq: IseqPtr) {
     asm_comment!(asm, "ZJIT entry point: {}", iseq_get_location(iseq, 0));
diff --git a/zjit/src/hir.rs b/zjit/src/hir.rs
index e7aaf64f28..358ecc58a9 100644
--- a/zjit/src/hir.rs
+++ b/zjit/src/hir.rs
@@ -440,6 +440,7 @@ pub enum SideExitReason {
     ObjToStringFallback,
     UnknownSpecialVariable(u64),
     UnhandledDefinedType(usize),
+    Interrupt,
 }
 
 impl std::fmt::Display for SideExitReason {
@@ -600,6 +601,10 @@ pub enum Insn {
 
     /// Increment a counter in ZJIT stats
     IncrCounter(Counter),
+
+    /// Equivalent of RUBY_VM_CHECK_INTS. Automatically inserted by the compiler before jumps and
+    /// return instructions.
+    CheckInterrupts { state: InsnId },
 }
 
 impl Insn {
@@ -610,7 +615,8 @@ impl Insn {
             | Insn::IfTrue { .. } | Insn::IfFalse { .. } | Insn::Return { .. }
             | Insn::PatchPoint { .. } | Insn::SetIvar { .. } | Insn::ArrayExtend { .. }
             | Insn::ArrayPush { .. } | Insn::SideExit { .. } | Insn::SetGlobal { .. }
-            | Insn::SetLocal { .. } | Insn::Throw { .. } | Insn::IncrCounter(_) => false,
+            | Insn::SetLocal { .. } | Insn::Throw { .. } | Insn::IncrCounter(_)
+            | Insn::CheckInterrupts { .. } => false,
             _ => true,
         }
     }
@@ -867,6 +873,7 @@ impl<'a> std::fmt::Display for InsnPrinter<'a> {
                 write!(f, ", {val}")
             }
             Insn::IncrCounter(counter) => write!(f, "IncrCounter {counter:?}"),
+            Insn::CheckInterrupts { .. } => write!(f, "CheckInterrupts"),
         }
     }
 }
@@ -1292,6 +1299,7 @@ impl Function {
             &ToNewArray { val, state } => ToNewArray { val: find!(val), state },
             &ArrayExtend { left, right, state } => ArrayExtend { left: find!(left), right: find!(right), state },
             &ArrayPush { array, val, state } => ArrayPush { array: find!(array), val: find!(val), state },
+            &CheckInterrupts { state } => CheckInterrupts { state },
         }
     }
 
@@ -1318,7 +1326,8 @@ impl Function {
             Insn::SetGlobal { .. } | Insn::Jump(_)
             | Insn::IfTrue { .. } | Insn::IfFalse { .. } | Insn::Return { .. } | Insn::Throw { .. }
             | Insn::PatchPoint { .. } | Insn::SetIvar { .. } | Insn::ArrayExtend { .. }
-            | Insn::ArrayPush { .. } | Insn::SideExit { .. } | Insn::SetLocal { .. } | Insn::IncrCounter(_) =>
+            | Insn::ArrayPush { .. } | Insn::SideExit { .. } | Insn::SetLocal { .. } | Insn::IncrCounter(_)
+            | Insn::CheckInterrupts { .. } =>
                 panic!("Cannot infer type of instruction with no output: {}", self.insns[insn.0]),
             Insn::Const { val: Const::Value(val) } => Type::from_value(*val),
             Insn::Const { val: Const::CBool(val) } => Type::from_cbool(*val),
@@ -1952,6 +1961,7 @@ impl Function {
             | &Insn::IncrCounter(_) =>
                 {}
             &Insn::PatchPoint { state, .. }
+            | &Insn::CheckInterrupts { state }
             | &Insn::GetConstantPath { ic: _, state } => {
                 worklist.push_back(state);
             }
-- 
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