cmov: Set asm options (#746)

Those options tell the compiler that ASM statements do not read
or write memory, can be removed if the dst ends up unused during
compilation, and that they don't push data to the stack.

cmov/src/lib.rs

@@ -23,7 +23,8 @@ pub fn cmovz(condition: usize, src: usize, dst: &mut usize) {
             "cmovz {1}, {2}",
             in(reg) condition,
             inlateout(reg) *dst,
-            in(reg) src
+            in(reg) src,
+            options(pure, nomem, nostack),
         };
     }
 }
@@ -44,6 +45,7 @@ pub fn cmovz(condition: usize, src: usize, dst: &mut usize) {
             inlateout(reg) *dst,
             in(reg) src,
             in(reg) *dst,
+            options(pure, nomem, nostack),
         };
     }
 }
@@ -64,6 +66,7 @@ pub fn cmovnz(condition: usize, src: usize, dst: &mut usize) {
             inlateout(reg) *dst,
             in(reg) src,
             in(reg) *dst,
+            options(pure, nomem, nostack),
         };
     }
 }
@@ -82,7 +85,8 @@ pub fn cmovnz(condition: usize, src: usize, dst: &mut usize) {
             "cmovnz {1}, {2}",
             in(reg) condition,
             inlateout(reg) *dst,
-            in(reg) src
+            in(reg) src,
+            options(pure, nomem, nostack),
         };
     }
 }