[WebAssembly] Add null streamer support

[aheejin]

Summary

Now llc -filetype=null works.

[aheejin]

• delete newlines

[aheejin]

• - Add __stack_pointer generation to test + add comment

[aheejin]

• Delete an assert for debugging

[eush]

Thank you! I think this is a better way to support MCNullStreamer than D54614.

lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h

97

What is virtual here for? It seems to be redundant since these functions are already declared virtual in the base class (hence the override).

test/CodeGen/WebAssembly/null-streamer.ll

13

Should there be a similar comment about .functype to explain g?

[aheejin]

• Address comments

lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h

97

Thanks, I blindly copy-pasted this from the parent class and forgot to delete them.

test/CodeGen/WebAssembly/null-streamer.ll

13

Actually we are planning changes (D54652, which will soon be landed) so that not only declared functions but also defined function will generate .functype directive. But anyway I think as you suggested having a second RUN line would be better than comments.

[aheejin]

• Delete unnecessary comments

[eush]

LGTM

lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp

 
 static MCTargetStreamer *createAsmTargetStreamer(MCStreamer &S,
                                                  formatted_raw_ostream &OS,
                                                  MCInstPrinter * /*InstPrint*/,
                                                  bool /*isVerboseAsm*/) {
   return new WebAssemblyTargetAsmStreamer(S, OS);
 }
 
+static MCTargetStreamer *createNullTargetStreamer(MCStreamer &S) {
+  return new WebAssemblyTargetNullStreamer(S);
+}
+
 // Force static initialization.
 extern "C" void LLVMInitializeWebAssemblyTargetMC() {
   for (Target *T :
        {&getTheWebAssemblyTarget32(), &getTheWebAssemblyTarget64()}) {
     // Register the MC asm info.
     RegisterMCAsmInfoFn X(*T, createMCAsmInfo);
 
     // Register the MC instruction info.
for (Target *T :
     // Register the MC subtarget info.
     TargetRegistry::RegisterMCSubtargetInfo(*T, createMCSubtargetInfo);
 
     // Register the object target streamer.
     TargetRegistry::RegisterObjectTargetStreamer(*T,
                                                  createObjectTargetStreamer);
     // Register the asm target streamer.
     TargetRegistry::RegisterAsmTargetStreamer(*T, createAsmTargetStreamer);
+    // Register the null target streamer.
+    TargetRegistry::RegisterNullTargetStreamer(*T, createNullTargetStreamer);
   }
 }
 
 wasm::ValType WebAssembly::toValType(const MVT &Ty) {
   switch (Ty.SimpleTy) {
   case MVT::i32:
     return wasm::ValType::I32;
   case MVT::i64:

lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h

public:
   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;
 };
 
+/// This part is for null output
+class WebAssemblyTargetNullStreamer final : public WebAssemblyTargetStreamer {
+public:
+  explicit WebAssemblyTargetNullStreamer(MCStreamer &S)
+      : WebAssemblyTargetStreamer(S) {}
+
+  virtual void emitParam(MCSymbol *Symbol, ArrayRef<MVT> Types) override {}
+  virtual void emitResult(MCSymbol *Symbol, ArrayRef<MVT> Types) override {}
+  virtual void emitLocal(ArrayRef<MVT> Types) override {}
+  virtual void emitEndFunc() override {}
+  virtual void emitIndirectFunctionType(MCSymbolWasm *Symbol) override {}
+  virtual void emitIndIdx(const MCExpr *Value) override {}
+  virtual void emitGlobalType(MCSymbolWasm *Sym) override {}
+  virtual void emitEventType(MCSymbolWasm *Sym) override {}
+  virtual void emitImportModule(MCSymbolWasm *Sym,
+                                StringRef ModuleName) override {}
+};
+
 } // end namespace llvm
 
 #endif

lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp

if (F.isDeclarationForLinker() && !F.isIntrinsic()) {
       // delcarations work in asm files.
       getTargetStreamer()->emitIndirectFunctionType(Sym);
 
       if (TM.getTargetTriple().isOSBinFormatWasm() &&
           F.hasFnAttribute("wasm-import-module")) {
         StringRef Name =
             F.getFnAttribute("wasm-import-module").getValueAsString();
         getTargetStreamer()->emitImportModule(Sym, Name);
+        assert(false);
       }
     }
   }
 
   for (const auto &G : M.globals()) {
     if (!G.hasInitializer() && G.hasExternalLinkage()) {
       if (G.getValueType()->isSized()) {
         uint16_t Size = M.getDataLayout().getTypeAllocSize(G.getValueType());

test/CodeGen/WebAssembly/null-streamer.ll

+; RUN: llc -O0 -filetype=null -exception-model=wasm -mattr=+exception-handling < %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+declare void @llvm.wasm.throw(i32, i8*)
+declare void @g()
+
+define i32 @test(i8* %p)  {
+  %n = alloca i32 ; This is to generate '.globaltype'
+  call void @llvm.wasm.throw(i32 0, i8* %p) ; This is to generate '.eventtype'
+  call void @g()
+  ret i32 0
+}