fix uxtb/uxth alias being incorrectly applied with x-size registers

2 files changed, 23 insertions, 13 deletions

diff --git a/src/armv8/a64.rs b/src/armv8/a64.rs
index c697c76..4cd91da 100644
--- a/src/armv8/a64.rs
+++ b/src/armv8/a64.rs
@@ -444,21 +444,15 @@ impl Display for Instruction {
             },
             Opcode::UBFM => {
                 // TODO: handle ubfx alias
-                if let Operand::Immediate(0) = self.operands[2] {
-                    let newdest = if let Operand::Register(_size, destnum) = self.operands[0] {
-                        Operand::Register(SizeCode::W, destnum)
-                    } else {
-                        unreachable!("operand 1 is always a register");
-                    };
-                    let newsrc = if let Operand::Register(_size, srcnum) = self.operands[1] {
-                        Operand::Register(SizeCode::W, srcnum)
-                    } else {
-                        unreachable!("operand 1 is always a register");
-                    };
+                if let (
+                    Operand::Register(SizeCode::W, destnum),
+                    Operand::Register(SizeCode::W, srcnum),
+                    Operand::Immediate(0)
+                ) = (self.operands[0], self.operands[1], self.operands[2]) {
                     if let Operand::Immediate(7) = self.operands[3] {
-                        return write!(fmt, "uxtb {}, {}", newdest, newsrc);
+                        return write!(fmt, "uxtb {}, {}", self.operands[0], self.operands[1]);
                     } else if let Operand::Immediate(15) = self.operands[3] {
-                        return write!(fmt, "uxth {}, {}", newdest, newsrc);
+                        return write!(fmt, "uxth {}, {}", self.operands[0], self.operands[1]);
                     }
                 }
                 if let Operand::Immediate(imms) = self.operands[3] {
diff --git a/tests/armv8/a64.rs b/tests/armv8/a64.rs
index 74bb89f..0e76ef6 100644
--- a/tests/armv8/a64.rs
+++ b/tests/armv8/a64.rs
@@ -4931,3 +4931,19 @@ fn test_misc() {
 
     assert!(errs.is_empty());
 }
+
+#[test]
+fn test_bitfield() {
+    const TESTS: &[([u8; 4], &'static str)] = &[
+        ([0x00, 0x1c, 0x40, 0xd3], "ubfx x0, x0, #0x0, #0x8"),
+        ([0x1f, 0x1c, 0x00, 0x53], "uxtb wzr, w0"),
+    ];
+
+    let errs = run_tests(TESTS);
+
+    for err in errs.iter() {
+        println!("{}", err);
+    }
+
+    assert!(errs.is_empty());
+}