Propagate Type::Nil when known

yjit/src/codegen.rs

@@ -1470,7 +1470,7 @@ fn gen_expandarray(
  ocb: &mut OutlinedCb,
 ) -> Option<CodegenStatus> {
  // Both arguments are rb_num_t which is unsigned
- let num = jit.get_arg(0).as_usize();
+ let num = jit.get_arg(0).as_u32();
  let flag = jit.get_arg(1).as_usize();
 
  // If this instruction has the splat flag, then bail out.
@@ -1535,7 +1535,34 @@ fn gen_expandarray(
  let array_reg = asm.load(array_opnd);
  let array_len_opnd = get_array_len(asm, array_reg);
 
+ /*
+ // FIXME: JCC_JB not implemented
  // Guard on the comptime/expected array length
+ if comptime_len >= num {
+ asm.comment(&format!("guard array length >= {}", num));
+ asm.cmp(array_len_opnd, num.into());
+ jit_chain_guard(
+ JCC_JB,
+ jit,
+ asm,
+ ocb,
+ OPT_AREF_MAX_CHAIN_DEPTH,
+ Counter::expandarray_chain_max_depth,
+ );
+ } else {
+ asm.comment(&format!("guard array length == {}", comptime_len));
+ asm.cmp(array_len_opnd, comptime_len.into());
+ jit_chain_guard(
+ JCC_JNE,
+ jit,
+ asm,
+ ocb,
+ OPT_AREF_MAX_CHAIN_DEPTH,
+ Counter::expandarray_chain_max_depth,
+ );
+ }
+ */
+
  asm.comment(&format!("guard array length == {}", comptime_len));
  asm.cmp(array_len_opnd, comptime_len.into());
  jit_chain_guard(
@@ -1575,12 +1602,12 @@ fn gen_expandarray(
 
  // Loop backward through the array and push each element onto the stack.
  for i in (0..num).rev() {
- let top = asm.stack_push(Type::Unknown);
- let offset = i32::try_from(i * SIZEOF_VALUE).unwrap();
+ let top = asm.stack_push(if i < comptime_len { Type::Unknown } else { Type::Nil });
+ let offset = i32::try_from(i * (SIZEOF_VALUE as u32)).unwrap();
 
  // Missing elements are Qnil
  asm.comment(&format!("load array[{}]", i));
- let elem_opnd = if (i as u32) < comptime_len { Opnd::mem(64, ary_opnd, offset) } else { Qnil.into() };
+ let elem_opnd = if i < comptime_len { Opnd::mem(64, ary_opnd, offset) } else { Qnil.into() };
  asm.mov(top, elem_opnd);
  }
  }