[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) {}
+
+  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

test/CodeGen/WebAssembly/null-streamer.ll

+; RUN: llc < %s -O0 -filetype=null -exception-model=wasm -mattr=+exception-handling
+; RUN: llc < %s -O0 -filetype=asm -asm-verbose=false -exception-model=wasm -mattr=+exception-handling | FileCheck %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
+  call void @llvm.wasm.throw(i32 0, i8* %p)
+  call void @g()
+  ret i32 0
+}
+
+; CHECK-DAG: .globaltype
+; CHECK-DAG: .eventtype
+; CHECK-DAG: .functype