ZJIT: Fix "memory operand with non-register base" (#14153)

test/ruby/test_zjit.rb

@@ -148,6 +148,18 @@ class TestZJIT < Test::Unit::TestCase
     }, call_threshold: 2
   end
 
+  def test_send_on_heap_object_in_spilled_arg
+    # This leads to a register spill, so not using `assert_compiles`
+    assert_runs 'Hash', %q{
+      def entry(a1, a2, a3, a4, a5, a6, a7, a8, a9)
+        a9.itself.class
+      end
+
+      entry(1, 2, 3, 4, 5, 6, 7, 8, {}) # profile
+      entry(1, 2, 3, 4, 5, 6, 7, 8, {})
+    }, call_threshold: 2
+  end
+
   def test_invokebuiltin
     omit 'Test fails at the moment due to not handling optional parameters'
     assert_compiles '["."]', %q{

zjit/src/backend/lir.rs

@@ -111,7 +111,7 @@ impl Opnd
                 })
             },
 
-            _ => unreachable!("memory operand with non-register base")
+            _ => unreachable!("memory operand with non-register base: {base:?}")
         }
     }
 

zjit/src/codegen.rs

@@ -1088,9 +1088,15 @@ fn gen_guard_type(jit: &mut JITState, asm: &mut Assembler, val: lir::Opnd, guard
     } else if let Some(expected_class) = guard_type.runtime_exact_ruby_class() {
         asm_comment!(asm, "guard exact class for non-immediate types");
 
-        let side_exit = side_exit(jit, state, GuardType(guard_type))?;
+        // If val isn't in a register, load it to use it as the base of Opnd::mem later.
+        // TODO: Max thinks codegen should not care about the shapes of the operands except to create them. (Shopify/ruby#685)
+        let val = match val {
+            Opnd::Reg(_) | Opnd::VReg { .. } => val,
+            _ => asm.load(val),
+        };
 
         // Check if it's a special constant
+        let side_exit = side_exit(jit, state, GuardType(guard_type))?;
         asm.test(val, (RUBY_IMMEDIATE_MASK as u64).into());
         asm.jnz(side_exit.clone());