ZJIT: Check for size >= expected in expandarray

Turns out `a, b = [1, 2, 3, 4]` is perfectly valid and just assigns `a =
1` and `b = 2` (and drops the rest). optcarrot relies on this. Allow it.

Author: tekknolagi

zjit/src/hir.rs

@@ -7449,7 +7449,8 @@ pub fn iseq_to_hir(iseq: *const rb_iseq_t) -> Result<Function, ParseError> {
                     let val = state.stack_pop()?;
                     let array = fun.push_insn(block, Insn::GuardType { val, guard_type: types::ArrayExact, state: exit_id, });
                     let length = fun.push_insn(block, Insn::ArrayLength { array });
-                    fun.push_insn(block, Insn::GuardBitEquals { val: length, expected: Const::CInt64(num as i64), reason: SideExitReason::ExpandArray, state: exit_id });
+                    let expected = fun.push_insn(block, Insn::Const { val: Const::CInt64(num as i64) });
+                    fun.push_insn(block, Insn::GuardGreaterEq { left: length, right: expected, reason: SideExitReason::ExpandArray, state: exit_id });
                     for i in (0..num).rev() {
                         // We do not emit a length guard here because in-bounds is already
                         // ensured by the expandarray length check above.

zjit/src/hir/tests.rs

@@ -3834,11 +3834,12 @@ pub mod hir_build_tests {
         bb2(v12:BasicObject, v13:BasicObject, v14:NilClass, v15:NilClass):
           v21:ArrayExact = GuardType v13, ArrayExact
           v22:CInt64 = ArrayLength v21
-          v23:CInt64[2] = GuardBitEquals v22, CInt64(2)
-          v24:CInt64[1] = Const CInt64(1)
-          v25:BasicObject = ArrayAref v21, v24
-          v26:CInt64[0] = Const CInt64(0)
-          v27:BasicObject = ArrayAref v21, v26
+          v23:CInt64[2] = Const CInt64(2)
+          v24:CInt64 = GuardGreaterEq v22, v23
+          v25:CInt64[1] = Const CInt64(1)
+          v26:BasicObject = ArrayAref v21, v25
+          v27:CInt64[0] = Const CInt64(0)
+          v28:BasicObject = ArrayAref v21, v27
           PatchPoint NoEPEscape(test)
           CheckInterrupts
           Return v13