Add logging

Author: LegNeato

crates/rustc_codegen_nvvm/src/link.rs

@@ -251,7 +251,8 @@ fn codegen_into_ptx_file(
 
     // object files (theyre not object files, they are impostors ඞ) are the bitcode modules produced by this codegen session
     // they *should* be the final crate.
-    for obj in objects {
+    for (i, obj) in objects.enumerate() {
+        debug!("Reading object file {}: {:?}", i, obj);
         let bitcode = std::fs::read(obj)?;
         modules.push(bitcode);
     }

crates/rustc_codegen_nvvm/src/nvvm.rs

@@ -159,7 +159,8 @@ unsafe fn cleanup_dicompileunit(module: &Module) {
 
 fn merge_llvm_modules(modules: Vec<Vec<u8>>, llcx: &Context) -> &Module {
     let module = unsafe { crate::create_module(llcx, "merged_modules") };
-    for merged_module in modules {
+    for (i, merged_module) in modules.iter().enumerate() {
+        debug!("Merging object file #{}", i);
         unsafe {
             let tmp = LLVMRustParseBitcodeForLTO(
                 llcx,