[WebAssembly] Add null streamer support

Summary: Now `llc -filetype=null` works.

Reviewers: eush

Subscribers: dschuff, jgravelle-google, sbc100, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D54660

llvm-svn: 347155

2 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
index 24dd5238f71..390f367c297 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
@@ -90,6 +90,10 @@ static MCTargetStreamer *createAsmTargetStreamer(MCStreamer &S,
   return new WebAssemblyTargetAsmStreamer(S, OS);
 }
 
+static MCTargetStreamer *createNullTargetStreamer(MCStreamer &S) {
+  return new WebAssemblyTargetNullStreamer(S);
+}
+
 // Force static initialization.
 extern "C" void LLVMInitializeWebAssemblyTargetMC() {
   for (Target *T :
@@ -120,6 +124,8 @@ extern "C" void LLVMInitializeWebAssemblyTargetMC() {
                                                  createObjectTargetStreamer);
     // Register the asm target streamer.
     TargetRegistry::RegisterAsmTargetStreamer(*T, createAsmTargetStreamer);
+    // Register the null target streamer.
+    TargetRegistry::RegisterNullTargetStreamer(*T, createNullTargetStreamer);
   }
 }
 
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
index 68527542e3e..3f1c6e158b2 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
@@ -88,6 +88,23 @@ public:
   void emitImportModule(MCSymbolWasm *Sym, StringRef ModuleName) override;
 };
 
+/// This part is for null output
+class WebAssemblyTargetNullStreamer final : public WebAssemblyTargetStreamer {
+public:
+  explicit WebAssemblyTargetNullStreamer(MCStreamer &S)
+      : WebAssemblyTargetStreamer(S) {}
+
+  void emitParam(MCSymbol *Symbol, ArrayRef<MVT> Types) override {}
+  void emitResult(MCSymbol *Symbol, ArrayRef<MVT> Types) override {}
+  void emitLocal(ArrayRef<MVT> Types) override {}
+  void emitEndFunc() override {}
+  void emitIndirectFunctionType(MCSymbolWasm *Symbol) override {}
+  void emitIndIdx(const MCExpr *Value) override {}
+  void emitGlobalType(MCSymbolWasm *Sym) override {}
+  void emitEventType(MCSymbolWasm *Sym) override {}
+  void emitImportModule(MCSymbolWasm *Sym, StringRef ModuleName) override {}
+};
+
 } // end namespace llvm
 
 #endif