ZJIT: constant fold bitwise AND (&) operations (ruby#16226)

Following up ruby#16225, I'm implementing fold on AND (&) operations.

- Ruby turns this operation into a C `&` in https://github.com/tomascco/ruby/blob/880eb3c76f09c44c85389ac5efbc555afafa3e6f/numeric.c#L5197-L5210
- Rustc compiler emits an `and` assembly instruction on x86: https://godbolt.org/z/Ee74vKTfb

So the operations are equivalent. I tested manually some cases and the results match.

Author: tomascco

zjit/src/hir.rs

@@ -4584,6 +4584,12 @@ impl Function {
                             _ => None,
                         })
                     }
+                    Insn::FixnumAnd { left, right, .. } => {
+                        self.fold_fixnum_bop(insn_id, left, right, |l, r| match (l, r) {
+                            (Some(l), Some(r)) => Some(l & r),
+                            _ => None,
+                        })
+                    }
                     Insn::FixnumEq { left, right, .. } => {
                         self.fold_fixnum_pred(insn_id, left, right, |l, r| match (l, r) {
                             (Some(l), Some(r)) => Some(l == r),

zjit/src/hir/opt_tests.rs

@@ -508,6 +508,66 @@ mod hir_opt_tests {
         ");
     }
 
+    #[test]
+    fn test_fold_fixnum_and() {
+        eval("
+            def test
+              4 & -7
+            end
+        ");
+
+        assert_snapshot!(inspect("test"), @"0");
+        assert_snapshot!(hir_string("test"), @"
+        fn test@<compiled>:3:
+        bb1():
+          EntryPoint interpreter
+          v1:BasicObject = LoadSelf
+          Jump bb3(v1)
+        bb2():
+          EntryPoint JIT(0)
+          v4:BasicObject = LoadArg :self@0
+          Jump bb3(v4)
+        bb3(v6:BasicObject):
+          v10:Fixnum[4] = Const Value(4)
+          v12:Fixnum[-7] = Const Value(-7)
+          PatchPoint MethodRedefined(Integer@0x1000, &@0x1008, cme:0x1010)
+          v25:Fixnum[0] = Const Value(0)
+          IncrCounter inline_cfunc_optimized_send_count
+          CheckInterrupts
+          Return v25
+        ");
+    }
+
+    #[test]
+    fn test_fold_fixnum_and_with_negative_self() {
+        eval("
+            def test
+              -4 & 7
+            end
+        ");
+
+        assert_snapshot!(inspect("test"), @"4");
+        assert_snapshot!(hir_string("test"), @"
+        fn test@<compiled>:3:
+        bb1():
+          EntryPoint interpreter
+          v1:BasicObject = LoadSelf
+          Jump bb3(v1)
+        bb2():
+          EntryPoint JIT(0)
+          v4:BasicObject = LoadArg :self@0
+          Jump bb3(v4)
+        bb3(v6:BasicObject):
+          v10:Fixnum[-4] = Const Value(-4)
+          v12:Fixnum[7] = Const Value(7)
+          PatchPoint MethodRedefined(Integer@0x1000, &@0x1008, cme:0x1010)
+          v25:Fixnum[4] = Const Value(4)
+          IncrCounter inline_cfunc_optimized_send_count
+          CheckInterrupts
+          Return v25
+        ");
+    }
+
     #[test]
     fn test_fold_fixnum_less() {
         eval("