Allow a target to create a null streamer.

Targets can assume that a target streamer is present, so they have to be able
to construct a null streamer in order to set the target streamer in it to.

Fixes a crash when using the null streamer with arm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211358 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 2 deletions

diff --git a/include/llvm/Support/TargetRegistry.h b/include/llvm/Support/TargetRegistry.h
index fcdc60490c..291fb1b95d 100644
--- a/include/llvm/Support/TargetRegistry.h
+++ b/include/llvm/Support/TargetRegistry.h
@@ -51,6 +51,7 @@ namespace llvm {
   class raw_ostream;
   class formatted_raw_ostream;
 
+  MCStreamer *createNullStreamer(MCContext &Ctx);
   MCStreamer *createAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
                                 bool isVerboseAsm, bool useDwarfDirectory,
                                 MCInstPrinter *InstPrint, MCCodeEmitter *CE,
@@ -139,6 +140,7 @@ namespace llvm {
                                              MCCodeEmitter *CE,
                                              MCAsmBackend *TAB,
                                              bool ShowInst);
+    typedef MCStreamer *(*NullStreamerCtorTy)(MCContext &Ctx);
     typedef MCRelocationInfo *(*MCRelocationInfoCtorTy)(StringRef TT,
                                                         MCContext &Ctx);
     typedef MCSymbolizer *(*MCSymbolizerCtorTy)(StringRef TT,
@@ -225,6 +227,10 @@ namespace llvm {
     /// AsmStreamer, if registered (default = llvm::createAsmStreamer).
     AsmStreamerCtorTy AsmStreamerCtorFn;
 
+    /// Construction function for this target's NullStreamer, if registered
+    /// (default = llvm::createNullStreamer).
+    NullStreamerCtorTy NullStreamerCtorFn;
+
     /// MCRelocationInfoCtorFn - Construction function for this target's
     /// MCRelocationInfo, if registered (default = llvm::createMCRelocationInfo)
     MCRelocationInfoCtorTy MCRelocationInfoCtorFn;
@@ -235,8 +241,8 @@ namespace llvm {
 
   public:
     Target()
-        : AsmStreamerCtorFn(nullptr), MCRelocationInfoCtorFn(nullptr),
-          MCSymbolizerCtorFn(nullptr) {}
+        : AsmStreamerCtorFn(nullptr), NullStreamerCtorFn(nullptr),
+          MCRelocationInfoCtorFn(nullptr), MCSymbolizerCtorFn(nullptr) {}
 
     /// @name Target Information
     /// @{
@@ -447,6 +453,12 @@ namespace llvm {
                                      InstPrint, CE, TAB, ShowInst);
     }
 
+    MCStreamer *createNullStreamer(MCContext &Ctx) const {
+      if (NullStreamerCtorFn)
+        return NullStreamerCtorFn(Ctx);
+      return llvm::createNullStreamer(Ctx);
+    }
+
     /// createMCRelocationInfo - Create a target specific MCRelocationInfo.
     ///
     /// \param TT The target triple.
@@ -780,6 +792,10 @@ namespace llvm {
       T.AsmStreamerCtorFn = Fn;
     }
 
+    static void RegisterNullStreamer(Target &T, Target::NullStreamerCtorTy Fn) {
+      T.NullStreamerCtorFn = Fn;
+    }
+
     /// RegisterMCRelocationInfo - Register an MCRelocationInfo
     /// implementation for the given target.
     ///