[FatLTO] output of -ffat-lto-objects -S should be assembly. (#79041)

Fat lto with -c compiles to an object file with the IR embedded in a
section of the object, the combination of fat-lto with -S should then
produce an assembly file equivalent of that. The IR output can still be
genreated by using both -S and -emit-llvm.

1 files changed, 4 insertions, 3 deletions

diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 1c32370..5c17091 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -4770,10 +4770,11 @@ Action *Driver::ConstructPhaseAction(
   case phases::Backend: {
     if (isUsingLTO() && TargetDeviceOffloadKind == Action::OFK_None) {
       types::ID Output;
-      if (Args.hasArg(options::OPT_S))
+      if (Args.hasArg(options::OPT_ffat_lto_objects))
+        Output = Args.hasArg(options::OPT_emit_llvm) ? types::TY_LTO_IR
+                                                     : types::TY_PP_Asm;
+      else if (Args.hasArg(options::OPT_S))
         Output = types::TY_LTO_IR;
-      else if (Args.hasArg(options::OPT_ffat_lto_objects))
-        Output = types::TY_PP_Asm;
       else
         Output = types::TY_LTO_BC;
       return C.MakeAction<BackendJobAction>(Input, Output);