Fix const handling and add tests for const operands

src/test/ui/asm/const.rs

@@ -0,0 +1,56 @@
+// no-system-llvm
+// only-x86_64
+// run-pass
+
+#![feature(asm)]
+
+use std::mem::size_of;
+
+trait Proj {
+    const C: usize;
+}
+impl Proj for i8 {
+    const C: usize = 8;
+}
+impl Proj for i16 {
+    const C: usize = 16;
+}
+
+const fn constfn(x: usize) -> usize {
+    x
+}
+
+fn generic<T: Proj>() {
+    unsafe {
+        let a: usize;
+        asm!("mov {}, {}", out(reg) a, const size_of::<T>());
+        assert_eq!(a, size_of::<T>());
+
+        let b: usize;
+        asm!("mov {}, {}", out(reg) b, const size_of::<T>() + constfn(5));
+        assert_eq!(b, size_of::<T>() + 5);
+
+        let c: usize;
+        asm!("mov {}, {}", out(reg) c, const T::C);
+        assert_eq!(c, T::C);
+    }
+}
+
+fn main() {
+    unsafe {
+        let a: usize;
+        asm!("mov {}, {}", out(reg) a, const 5);
+        assert_eq!(a, 5);
+
+        let b: usize;
+        asm!("mov {}, {}", out(reg) b, const constfn(5));
+        assert_eq!(b, 5);
+
+        let c: usize;
+        asm!("mov {}, {}", out(reg) c, const constfn(5) + constfn(5));
+        assert_eq!(c, 10);
+    }
+
+    generic::<i8>();
+    generic::<i16>();
+}