Reapply "Change -save-temps to emit unoptimized bitcode files."

This reapplies r224503 along with a fix for compiling Fortran by having the
clang driver invoke gcc (see r224546, where it was reverted). I have added
a testcase for that as well.

Original commit message:
It is often convenient to use -save-temps to collect the intermediate
results of a compilation, e.g., when triaging a bug report. Besides the
temporary files for preprocessed source and assembly code, this adds the
unoptimized bitcode files as well.

This adds a new BackendJobAction, which is mostly mechanical, to run after
the CompileJobAction. When not using -save-temps, the BackendJobAction is
combined into one job with the CompileJobAction, similar to the way the
integrated assembler is handled. I've implemented this entirely as a
driver change, so under the hood, it is just using -disable-llvm-optzns
to get the unoptimized bitcode.

Based in part on a patch by Steven Wu.
rdar://problem/18909437

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@224688 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/Driver/Phases.cpp b/lib/Driver/Phases.cpp
index 155e53b64f..7ae270857f 100644
--- a/lib/Driver/Phases.cpp
+++ b/lib/Driver/Phases.cpp
@@ -18,6 +18,7 @@ const char *phases::getPhaseName(ID Id) {
   case Preprocess: return "preprocessor";
   case Precompile: return "precompiler";
   case Compile: return "compiler";
+  case Backend: return "backend";
   case Assemble: return "assembler";
   case Link: return "linker";
   }