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

llvm-svn: 224688

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/lib/Driver/Tools.h b/clang/lib/Driver/Tools.h
index 59af8a0ec97..6647f39ce81 100644
--- a/clang/lib/Driver/Tools.h
+++ b/clang/lib/Driver/Tools.h
@@ -95,6 +95,7 @@ using llvm::opt::ArgStringList;
     bool hasGoodDiagnostics() const override { return true; }
     bool hasIntegratedAssembler() const override { return true; }
     bool hasIntegratedCPP() const override { return true; }
+    bool canEmitIR() const override { return true; }
 
     void ConstructJob(Compilation &C, const JobAction &JA,
                       const InputInfo &Output, const InputInfoList &Inputs,