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

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),
+        : AsmStreamerCtorFn(nullptr), NullStreamerCtorFn(nullptr),
-          MCSymbolizerCtorFn(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.
     ///

lib/CodeGen/LLVMTargetMachine.cpp

@@ -209,7 +209,7 @@ bool LLVMTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
   case CGFT_Null:
     // The Null output is intended for use for performance analysis and testing,
     // not real users.
-    AsmStreamer.reset(createNullStreamer(*Context));
+    AsmStreamer.reset(getTarget().createNullStreamer(*Context));
     break;
   }
 

lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp

@@ -1332,6 +1332,12 @@ MCStreamer *createMCAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
   return S;
 }
 
+MCStreamer *createARMNullStreamer(MCContext &Ctx) {
+  MCStreamer *S = llvm::createNullStreamer(Ctx);
+  new ARMTargetStreamer(*S);
+  return S;
+}
+
   MCELFStreamer* createARMELFStreamer(MCContext &Context, MCAsmBackend &TAB,
                                       raw_ostream &OS, MCCodeEmitter *Emitter,
                                       bool RelaxAll, bool NoExecStack,

lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp

@@ -427,6 +427,12 @@ extern "C" void LLVMInitializeARMTargetMC() {
   TargetRegistry::RegisterAsmStreamer(TheThumbLETarget, createMCAsmStreamer);
   TargetRegistry::RegisterAsmStreamer(TheThumbBETarget, createMCAsmStreamer);
 
+  // Register the null streamer.
+  TargetRegistry::RegisterNullStreamer(TheARMLETarget, createARMNullStreamer);
+  TargetRegistry::RegisterNullStreamer(TheARMBETarget, createARMNullStreamer);
+  TargetRegistry::RegisterNullStreamer(TheThumbLETarget, createARMNullStreamer);
+  TargetRegistry::RegisterNullStreamer(TheThumbBETarget, createARMNullStreamer);
+
   // Register the MCInstPrinter.
   TargetRegistry::RegisterMCInstPrinter(TheARMLETarget, createARMMCInstPrinter);
   TargetRegistry::RegisterMCInstPrinter(TheARMBETarget, createARMMCInstPrinter);

lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h

@@ -51,6 +51,8 @@ MCStreamer *createMCAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
                                 MCInstPrinter *InstPrint, MCCodeEmitter *CE,
                                 MCAsmBackend *TAB, bool ShowInst);
 
+MCStreamer *createARMNullStreamer(MCContext &Ctx);
+
 MCCodeEmitter *createARMLEMCCodeEmitter(const MCInstrInfo &MCII,
                                         const MCRegisterInfo &MRI,
                                         const MCSubtargetInfo &STI,

lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp

@@ -40,78 +40,34 @@ void ARMTargetStreamer::finish() { ConstantPools->emitAll(Streamer); }
 
 // The remaining callbacks should be handled separately by each
 // streamer.
-void ARMTargetStreamer::emitFnStart() {
+void ARMTargetStreamer::emitFnStart() {}
-  llvm_unreachable("unimplemented");
+void ARMTargetStreamer::emitFnEnd() {}
-}
+void ARMTargetStreamer::emitCantUnwind() {}
-void ARMTargetStreamer::emitFnEnd() {
+void ARMTargetStreamer::emitPersonality(const MCSymbol *Personality) {}
-  llvm_unreachable("unimplemented");
+void ARMTargetStreamer::emitPersonalityIndex(unsigned Index) {}
-}
+void ARMTargetStreamer::emitHandlerData() {}
-void ARMTargetStreamer::emitCantUnwind() {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::emitPersonality(const MCSymbol *Personality) {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::emitPersonalityIndex(unsigned Index) {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::emitHandlerData() {
-  llvm_unreachable("unimplemented");
-}
 void ARMTargetStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
-                                       int64_t Offset) {
+                                  int64_t Offset) {}
-  llvm_unreachable("unimplemented");
+void ARMTargetStreamer::emitMovSP(unsigned Reg, int64_t Offset) {}
-}
+void ARMTargetStreamer::emitPad(int64_t Offset) {}
-void ARMTargetStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
+void ARMTargetStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
-  llvm_unreachable("unimplemented");
+                                    bool isVector) {}
-}
+void ARMTargetStreamer::emitUnwindRaw(int64_t StackOffset,
-void ARMTargetStreamer::emitPad(int64_t Offset) {
+                                      const SmallVectorImpl<uint8_t> &Opcodes) {
-  llvm_unreachable("unimplemented");
-}
-void
-ARMTargetStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
-                                    bool isVector) {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::emitUnwindRaw(
-    int64_t StackOffset, const SmallVectorImpl<uint8_t> &Opcodes) {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::switchVendor(StringRef Vendor) {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
-  llvm_unreachable("unimplemented");
 }
+void ARMTargetStreamer::switchVendor(StringRef Vendor) {}
+void ARMTargetStreamer::emitAttribute(unsigned Attribute, unsigned Value) {}
 void ARMTargetStreamer::emitTextAttribute(unsigned Attribute,
-                                               StringRef String) {
+                                          StringRef String) {}
-  llvm_unreachable("unimplemented");
-}
 void ARMTargetStreamer::emitIntTextAttribute(unsigned Attribute,
-                                                  unsigned IntValue,
+                                             unsigned IntValue,
-                                                  StringRef StringValue) {
+                                             StringRef StringValue) {}
-  llvm_unreachable("unimplemented");
+void ARMTargetStreamer::emitArch(unsigned Arch) {}
-}
+void ARMTargetStreamer::emitObjectArch(unsigned Arch) {}
-void ARMTargetStreamer::emitArch(unsigned Arch) {
+void ARMTargetStreamer::emitFPU(unsigned FPU) {}
-  llvm_unreachable("unimplemented");
+void ARMTargetStreamer::finishAttributeSection() {}
-}
+void ARMTargetStreamer::emitInst(uint32_t Inst, char Suffix) {}
-void ARMTargetStreamer::emitObjectArch(unsigned Arch) {
+void
-  llvm_unreachable("unimplemented");
+ARMTargetStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) {}
-}
-void ARMTargetStreamer::emitFPU(unsigned FPU) {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::finishAttributeSection() {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::emitInst(uint32_t Inst, char Suffix) {
-  llvm_unreachable("unimplemented");
-}
-void ARMTargetStreamer::AnnotateTLSDescriptorSequence(
-    const MCSymbolRefExpr *SRE) {
-  llvm_unreachable("unimplemented");
-}
 
-void ARMTargetStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
+void ARMTargetStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {}
-  llvm_unreachable("unimplemented");
-}

test/DebugInfo/global.ll

@@ -6,6 +6,9 @@
 ; Also test that the null streamer doesn't crash with debug info.
 ; RUN: %llc_dwarf -O0 -filetype=null < %s
 
+; Test the null streamer with a terget streamer too.
+; RUN: llc -O0 -filetype=null -mtriple=arm-linux < %s
+
 ; generated from the following source compiled to bitcode with clang -g -O1
 ; static int i;
 ; int main() {