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, 17 insertions, 6 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 20d14bf..1c5a9aa 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2002,7 +2002,7 @@ static bool ShouldDisableDwarfDirectory(const ArgList &Args,
 
 /// \brief Check whether the given input tree contains any compilation actions.
 static bool ContainsCompileAction(const Action *A) {
-  if (isa<CompileJobAction>(A))
+  if (isa<CompileJobAction>(A) || isa<BackendJobAction>(A))
     return true;
 
   for (const auto &Act : *A)
@@ -2528,7 +2528,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   } else if (isa<VerifyPCHJobAction>(JA)) {
     CmdArgs.push_back("-verify-pch");
   } else {
-    assert(isa<CompileJobAction>(JA) && "Invalid action for clang tool.");
+    assert((isa<CompileJobAction>(JA) || isa<BackendJobAction>(JA)) &&
+           "Invalid action for clang tool.");
 
     if (JA.getType() == types::TY_Nothing) {
       CmdArgs.push_back("-fsyntax-only");
@@ -4405,18 +4406,27 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // Forward -Xclang arguments to -cc1, and -mllvm arguments to the LLVM option
   // parser.
   Args.AddAllArgValues(CmdArgs, options::OPT_Xclang);
+  bool OptDisabled = false;
   for (arg_iterator it = Args.filtered_begin(options::OPT_mllvm),
          ie = Args.filtered_end(); it != ie; ++it) {
     (*it)->claim();
 
     // We translate this by hand to the -cc1 argument, since nightly test uses
     // it and developers have been trained to spell it with -mllvm.
-    if (StringRef((*it)->getValue(0)) == "-disable-llvm-optzns")
+    if (StringRef((*it)->getValue(0)) == "-disable-llvm-optzns") {
       CmdArgs.push_back("-disable-llvm-optzns");
-    else
+      OptDisabled = true;
+    } else
       (*it)->render(Args, CmdArgs);
   }
 
+  // With -save-temps, we want to save the unoptimized bitcode output from the
+  // CompileJobAction, so disable optimizations if they are not already
+  // disabled.
+  if (Args.hasArg(options::OPT_save_temps) && !OptDisabled &&
+      isa<CompileJobAction>(JA))
+    CmdArgs.push_back("-disable-llvm-optzns");
+
   if (Output.getType() == types::TY_Dependencies) {
     // Handled with other dependency code.
   } else if (Output.isFilename()) {
@@ -4462,7 +4472,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // can propagate it to the backend.
   bool SplitDwarf = Args.hasArg(options::OPT_gsplit_dwarf) &&
     getToolChain().getTriple().isOSLinux() &&
-    (isa<AssembleJobAction>(JA) || isa<CompileJobAction>(JA));
+    (isa<AssembleJobAction>(JA) || isa<CompileJobAction>(JA) ||
+     isa<BackendJobAction>(JA));
   const char *SplitDwarfOut;
   if (SplitDwarf) {
     CmdArgs.push_back("-split-dwarf-file");
@@ -4486,7 +4497,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // Handle the debug info splitting at object creation time if we're
   // creating an object.
   // TODO: Currently only works on linux with newer objcopy.
-  if (SplitDwarf && !isa<CompileJobAction>(JA))
+  if (SplitDwarf && !isa<CompileJobAction>(JA) && !isa<BackendJobAction>(JA))
     SplitDebugInfo(getToolChain(), C, *this, JA, Args, Output, SplitDwarfOut);
 
   if (Arg *A = Args.getLastArg(options::OPT_pg))