ZJIT: Inline Array#empty?

2 files changed, 20 insertions, 4 deletions

diff --git a/zjit/src/cruby_methods.rs b/zjit/src/cruby_methods.rs
index e6c26148cf..2d5bb3b62f 100644
--- a/zjit/src/cruby_methods.rs
+++ b/zjit/src/cruby_methods.rs
@@ -220,7 +220,7 @@ pub fn init() -> Annotations {
     annotate!(rb_cModule, "name", types::StringExact.union(types::NilClass), no_gc, leaf, elidable);
     annotate!(rb_cModule, "===", inline_module_eqq, types::BoolExact, no_gc, leaf);
     annotate!(rb_cArray, "length", inline_array_length, types::Fixnum, no_gc, leaf, elidable);
-    annotate!(rb_cArray, "empty?", types::BoolExact, no_gc, leaf, elidable);
+    annotate!(rb_cArray, "empty?", inline_array_empty_p, types::BoolExact, no_gc, leaf, elidable);
     annotate!(rb_cArray, "reverse", types::ArrayExact, leaf, elidable);
     annotate!(rb_cArray, "join", types::StringExact);
     annotate!(rb_cArray, "[]", inline_array_aref);
@@ -547,6 +547,19 @@ fn inline_array_length(fun: &mut hir::Function, block: hir::BlockId, recv: hir::
     None
 }
 
+fn inline_array_empty_p(fun: &mut hir::Function, block: hir::BlockId, recv: hir::InsnId, args: &[hir::InsnId], state: hir::InsnId) -> Option<hir::InsnId> {
+    let &[] = args else { return None; };
+    if fun.likely_a(recv, types::Array, state) {
+        let recv = fun.coerce_to(block, recv, types::Array, state);
+        let length_cint = fun.push_insn(block, hir::Insn::ArrayLength { array: recv });
+        let zero = fun.push_insn(block, hir::Insn::Const { val: hir::Const::CInt64(0) });
+        let result_c = fun.push_insn(block, hir::Insn::IsBitEqual { left: length_cint, right: zero });
+        let result = fun.push_insn(block, hir::Insn::BoxBool { val: result_c });
+        return Some(result);
+    }
+    None
+}
+
 fn inline_integer_succ(fun: &mut hir::Function, block: hir::BlockId, recv: hir::InsnId, args: &[hir::InsnId], state: hir::InsnId) -> Option<hir::InsnId> {
     if !args.is_empty() { return None; }
     if fun.likely_a(recv, types::Fixnum, state) {
diff --git a/zjit/src/hir/opt_tests.rs b/zjit/src/hir/opt_tests.rs
index 4fc47dc611..3b6f694810 100644
--- a/zjit/src/hir/opt_tests.rs
+++ b/zjit/src/hir/opt_tests.rs
@@ -5411,7 +5411,7 @@ mod hir_opt_tests {
     }
 
     #[test]
-    fn test_specialize_array_empty_p_to_ccall() {
+    fn test_specialize_array_empty_p() {
         eval("
             def test(a) = a.empty?
 
@@ -5431,10 +5431,13 @@ mod hir_opt_tests {
           PatchPoint MethodRedefined(Array@0x1000, empty?@0x1008, cme:0x1010)
           PatchPoint NoSingletonClass(Array@0x1000)
           v23:ArrayExact = GuardType v9, ArrayExact
+          v24:CInt64 = ArrayLength v23
+          v25:CInt64[0] = Const CInt64(0)
+          v26:CBool = IsBitEqual v24, v25
+          v27:BoolExact = BoxBool v26
           IncrCounter inline_cfunc_optimized_send_count
-          v25:BoolExact = CCall v23, :Array#empty?@0x1038
           CheckInterrupts
-          Return v25
+          Return v27
         ");
     }