rustc: Start implementing compat with LLVM 9

This commit doesn't actually migrate to LLVM 9, but it brings our own
C++ bindings in line with LLVM 9 and able to compile against tip of
tree. The changes made were:

* The `MainSubprogram` flag for debuginfo moved between flag types.
* Iteration of archive members was tweaked slightly and we have to
  construct the two iterators before constructing the returned
  `RustArchiveIterator` value.
* The `getOrInsertFunction` binding now returns a wrapper which we use
  `getCallee()` on to get the value we're interested in.

1 files changed, 5 insertions, 6 deletions

diff --git a/src/librustc_codegen_llvm/debuginfo/mod.rs b/src/librustc_codegen_llvm/debuginfo/mod.rs
index 6abbcd9feba..57e4ac07d5e 100644
--- a/src/librustc_codegen_llvm/debuginfo/mod.rs
+++ b/src/librustc_codegen_llvm/debuginfo/mod.rs
@@ -296,12 +296,6 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
 
         let mut flags = DIFlags::FlagPrototyped;
 
-        if let Some((id, _)) = self.tcx.entry_fn(LOCAL_CRATE) {
-            if id == def_id {
-                flags |= DIFlags::FlagMainSubprogram;
-            }
-        }
-
         if self.layout_of(sig.output()).abi.is_uninhabited() {
             flags |= DIFlags::FlagNoReturn;
         }
@@ -313,6 +307,11 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         if self.sess().opts.optimize != config::OptLevel::No {
             spflags |= DISPFlags::SPFlagOptimized;
         }
+        if let Some((id, _)) = self.tcx.entry_fn(LOCAL_CRATE) {
+            if id == def_id {
+                spflags |= DISPFlags::SPFlagMainSubprogram;
+            }
+        }
 
         let fn_metadata = unsafe {
             llvm::LLVMRustDIBuilderCreateFunction(