Rollup merge of #57573 - Xanewok:querify-entry-fn, r=Zoxc

Querify `entry_fn`

Analogous to https://github.com/rust-lang/rust/pull/57570 but this will also require few fixups in Miri so I decided to separate that (and it seems [CI doesn't let us break tools anymore](https://github.com/rust-lang/rust/pull/57392#issuecomment-453801540)? Or was that because it was a rollup PR?)

r? @nikomatsakis

1 files changed, 3 insertions, 4 deletions

diff --git a/src/librustc_codegen_llvm/debuginfo/mod.rs b/src/librustc_codegen_llvm/debuginfo/mod.rs
index 2eab626ae8e..b504aa515fd 100644
--- a/src/librustc_codegen_llvm/debuginfo/mod.rs
+++ b/src/librustc_codegen_llvm/debuginfo/mod.rs
@@ -14,7 +14,7 @@ use llvm;
 use llvm::debuginfo::{DIFile, DIType, DIScope, DIBuilder, DISubprogram, DIArray, DIFlags,
     DILexicalBlock};
 use rustc::hir::CodegenFnAttrFlags;
-use rustc::hir::def_id::{DefId, CrateNum};
+use rustc::hir::def_id::{DefId, CrateNum, LOCAL_CRATE};
 use rustc::ty::subst::{Substs, UnpackedKind};
 
 use abi::Abi;
@@ -290,9 +290,8 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
 
         let mut flags = DIFlags::FlagPrototyped;
 
-        let local_id = self.tcx().hir().as_local_node_id(def_id);
-        if let Some((id, _, _)) = *self.sess().entry_fn.borrow() {
-            if local_id == Some(id) {
+        if let Some((id, _)) = self.tcx.entry_fn(LOCAL_CRATE) {
+            if id == def_id {
                 flags |= DIFlags::FlagMainSubprogram;
             }
         }