review updates

Author: x17jiri

compiler/rustc_codegen_llvm/src/builder.rs

@@ -211,6 +211,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         match expect {
             ExpectKind::None => {}
             ExpectKind::True | ExpectKind::False => unsafe {
+                // Use weights 2000 and 1, which is what Clang uses
                 let s = "branch_weights";
                 let v = [
                     llvm::LLVMMDStringInContext(

compiler/rustc_middle/src/mir/syntax.rs

@@ -421,8 +421,13 @@ impl StatementKind<'_> {
     TypeVisitable
 )]
 pub enum ExpectKind {
-    True,  // condition is probably true
-    False, // condition is probably false
+    /// condition is probably true
+    True,
+
+    /// condition is probably false
+    False,
+
+    /// condition is unpredictable by hardware
     Unpredictable,
 }