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

7 files changed, 76 insertions, 17 deletions

diff --git a/clang/lib/Driver/Action.cpp b/clang/lib/Driver/Action.cpp
index d4f339d376d..360dbeecabf 100644
--- a/clang/lib/Driver/Action.cpp
+++ b/clang/lib/Driver/Action.cpp
@@ -29,6 +29,7 @@ const char *Action::getClassName(ActionClass AC) {
   case AnalyzeJobClass: return "analyzer";
   case MigrateJobClass: return "migrator";
   case CompileJobClass: return "compiler";
+  case BackendJobClass: return "backend";
   case AssembleJobClass: return "assembler";
   case LinkJobClass: return "linker";
   case LipoJobClass: return "lipo";
@@ -92,6 +93,12 @@ CompileJobAction::CompileJobAction(std::unique_ptr<Action> Input,
                                    types::ID OutputType)
     : JobAction(CompileJobClass, std::move(Input), OutputType) {}
 
+void BackendJobAction::anchor() {}
+
+BackendJobAction::BackendJobAction(std::unique_ptr<Action> Input,
+                                   types::ID OutputType)
+    : JobAction(BackendJobClass, std::move(Input), OutputType) {}
+
 void AssembleJobAction::anchor() {}
 
 AssembleJobAction::AssembleJobAction(std::unique_ptr<Action> Input,
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 99d84432dee..1f9e11afdc4 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -165,7 +165,7 @@ const {
       (PhaseArg = DAL.getLastArg(options::OPT__SLASH_P))) {
     FinalPhase = phases::Preprocess;
 
-    // -{fsyntax-only,-analyze,emit-ast,S} only run up to the compiler.
+    // -{fsyntax-only,-analyze,emit-ast} only run up to the compiler.
   } else if ((PhaseArg = DAL.getLastArg(options::OPT_fsyntax_only)) ||
              (PhaseArg = DAL.getLastArg(options::OPT_module_file_info)) ||
              (PhaseArg = DAL.getLastArg(options::OPT_verify_pch)) ||
@@ -174,10 +174,13 @@ const {
              (PhaseArg = DAL.getLastArg(options::OPT__migrate)) ||
              (PhaseArg = DAL.getLastArg(options::OPT__analyze,
                                         options::OPT__analyze_auto)) ||
-             (PhaseArg = DAL.getLastArg(options::OPT_emit_ast)) ||
-             (PhaseArg = DAL.getLastArg(options::OPT_S))) {
+             (PhaseArg = DAL.getLastArg(options::OPT_emit_ast))) {
     FinalPhase = phases::Compile;
 
+    // -S only runs up to the backend.
+  } else if ((PhaseArg = DAL.getLastArg(options::OPT_S))) {
+    FinalPhase = phases::Backend;
+
     // -c only runs up to the assembler.
   } else if ((PhaseArg = DAL.getLastArg(options::OPT_c))) {
     FinalPhase = phases::Assemble;
@@ -849,7 +852,9 @@ void Driver::PrintActions(const Compilation &C) const {
 /// \brief Check whether the given input tree contains any compilation or
 /// assembly actions.
 static bool ContainsCompileOrAssembleAction(const Action *A) {
-  if (isa<CompileJobAction>(A) || isa<AssembleJobAction>(A))
+  if (isa<CompileJobAction>(A) ||
+      isa<BackendJobAction>(A) ||
+      isa<AssembleJobAction>(A))
     return true;
 
   for (Action::const_iterator it = A->begin(), ie = A->end(); it != ie; ++it)
@@ -1346,17 +1351,21 @@ Driver::ConstructPhaseAction(const ArgList &Args, phases::ID Phase,
     if (Args.hasArg(options::OPT_verify_pch))
       return llvm::make_unique<VerifyPCHJobAction>(std::move(Input),
                                                    types::TY_Nothing);
+    return llvm::make_unique<CompileJobAction>(std::move(Input),
+                                               types::TY_LLVM_BC);
+  }
+  case phases::Backend: {
     if (IsUsingLTO(Args)) {
       types::ID Output =
         Args.hasArg(options::OPT_S) ? types::TY_LTO_IR : types::TY_LTO_BC;
-      return llvm::make_unique<CompileJobAction>(std::move(Input), Output);
+      return llvm::make_unique<BackendJobAction>(std::move(Input), Output);
     }
     if (Args.hasArg(options::OPT_emit_llvm)) {
       types::ID Output =
         Args.hasArg(options::OPT_S) ? types::TY_LLVM_IR : types::TY_LLVM_BC;
-      return llvm::make_unique<CompileJobAction>(std::move(Input), Output);
+      return llvm::make_unique<BackendJobAction>(std::move(Input), Output);
     }
-    return llvm::make_unique<CompileJobAction>(std::move(Input),
+    return llvm::make_unique<BackendJobAction>(std::move(Input),
                                                types::TY_PP_Asm);
   }
   case phases::Assemble:
@@ -1494,12 +1503,34 @@ static const Tool *SelectToolForJob(Compilation &C, const ToolChain *TC,
       !C.getArgs().hasArg(options::OPT__SLASH_FA) &&
       !C.getArgs().hasArg(options::OPT__SLASH_Fa) &&
       isa<AssembleJobAction>(JA) &&
-      Inputs->size() == 1 && isa<CompileJobAction>(*Inputs->begin())) {
-    const Tool *Compiler =
-      TC->SelectTool(cast<JobAction>(**Inputs->begin()));
+      Inputs->size() == 1 && isa<BackendJobAction>(*Inputs->begin())) {
+    // A BackendJob is always preceded by a CompileJob, and without
+    // -save-temps they will always get combined together, so instead of
+    // checking the backend tool, check if the tool for the CompileJob
+    // has an integrated assembler.
+    const ActionList *BackendInputs = &(*Inputs)[0]->getInputs();
+    JobAction *CompileJA = cast<CompileJobAction>(*BackendInputs->begin());
+    const Tool *Compiler = TC->SelectTool(*CompileJA);
     if (!Compiler)
       return nullptr;
     if (Compiler->hasIntegratedAssembler()) {
+      Inputs = &(*BackendInputs)[0]->getInputs();
+      ToolForJob = Compiler;
+    }
+  }
+
+  // A backend job should always be combined with the preceding compile job
+  // unless OPT_save_temps is enabled and the compiler is capable of emitting
+  // LLVM IR as an intermediate output.
+  if (isa<BackendJobAction>(JA)) {
+    // Check if the compiler supports emitting LLVM IR.
+    assert(Inputs->size() == 1);
+    JobAction *CompileJA = cast<CompileJobAction>(*Inputs->begin());
+    const Tool *Compiler = TC->SelectTool(*CompileJA);
+    if (!Compiler)
+      return nullptr;
+    if (!Compiler->canEmitIR() ||
+        !C.getArgs().hasArg(options::OPT_save_temps)) {
       Inputs = &(*Inputs)[0]->getInputs();
       ToolForJob = Compiler;
     }
@@ -1751,6 +1782,12 @@ const char *Driver::GetNamedOutputPath(Compilation &C,
       Suffixed += "-";
       Suffixed.append(BoundArch);
     }
+    // When using both -save-temps and -emit-llvm, use a ".tmp.bc" suffix for
+    // the unoptimized bitcode so that it does not get overwritten by the ".bc"
+    // optimized bitcode output.
+    if (!AtTopLevel && C.getArgs().hasArg(options::OPT_emit_llvm) &&
+        JA.getType() == types::TY_LLVM_BC)
+      Suffixed += ".tmp";
     Suffixed += '.';
     Suffixed += Suffix;
     NamedOutput = C.getArgs().MakeArgString(Suffixed.c_str());
@@ -2083,7 +2120,7 @@ bool Driver::ShouldUseClangCompiler(const JobAction &JA) const {
 
   // Otherwise make sure this is an action clang understands.
   if (!isa<PreprocessJobAction>(JA) && !isa<PrecompileJobAction>(JA) &&
-      !isa<CompileJobAction>(JA))
+      !isa<CompileJobAction>(JA) && !isa<BackendJobAction>(JA))
     return false;
 
   return true;
diff --git a/clang/lib/Driver/Phases.cpp b/clang/lib/Driver/Phases.cpp
index 155e53b64fc..7ae270857f4 100644
--- a/clang/lib/Driver/Phases.cpp
+++ b/clang/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";
   }
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 6734ce7d709..2bcfecf6bde 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -129,6 +129,7 @@ Tool *ToolChain::getTool(Action::ActionClass AC) const {
   case Action::AnalyzeJobClass:
   case Action::MigrateJobClass:
   case Action::VerifyPCHJobClass:
+  case Action::BackendJobClass:
     return getClang();
   }
 
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 20d14bf36c4..1c5a9aa4046 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))
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,
diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
index 4a22dcff46a..6ee764c64e3 100644
--- a/clang/lib/Driver/Types.cpp
+++ b/clang/lib/Driver/Types.cpp
@@ -203,6 +203,7 @@ void types::getCompilationPhases(ID Id, llvm::SmallVectorImpl<phases::ID> &P) {
     } else {
       if (!onlyAssembleType(Id)) {
         P.push_back(phases::Compile);
+        P.push_back(phases::Backend);
       }
       P.push_back(phases::Assemble);
     }