Auto merge of #38217 - oli-obk:mir-for-all-and-all-for-mir, r=eddyb

add a -Z flag to guarantee that MIR is generated for all functions

r? @eddyb

cc @solson

src/librustc/middle/cstore.rs

@@ -355,6 +355,11 @@ pub trait CrateStore<'tcx> {
     fn get_item_mir<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> Mir<'tcx>;
     fn is_item_mir_available(&self, def: DefId) -> bool;
 
+    /// Take a look if we need to inline or monomorphize this. If so, we
+    /// will emit code for this item in the local crate, and thus
+    /// create a translation item for it.
+    fn can_have_local_instance<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> bool;
+
     // This is basically a 1-based range of ints, which is a little
     // silly - I may fix that.
     fn crates(&self) -> Vec<CrateNum>;
@@ -528,6 +533,9 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
     fn is_item_mir_available(&self, def: DefId) -> bool {
         bug!("is_item_mir_available")
     }
+    fn can_have_local_instance<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> bool {
+        bug!("can_have_local_instance")
+    }
 
     // This is basically a 1-based range of ints, which is a little
     // silly - I may fix that.

src/librustc/session/config.rs

@@ -928,6 +928,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "print some statistics about AST and HIR"),
     mir_stats: bool = (false, parse_bool, [UNTRACKED],
           "print some statistics about MIR"),
+    always_encode_mir: bool = (false, parse_bool, [TRACKED],
+          "encode MIR of all functions into the crate metadata"),
 }
 
 pub fn default_lib_output() -> CrateType {