[WebAssembly] Remove WASM_STACK_POINTER.

WASM_STACK_POINTER and the .stack_pointer directive are no longer needed
now that the stack pointer global is an import.

llvm-svn: 319956

include/llvm/BinaryFormat/Wasm.h

@@ -182,7 +182,6 @@ enum class ValType {
 
 // Linking metadata kinds.
 enum : unsigned {
-  WASM_STACK_POINTER  = 0x1,
   WASM_SYMBOL_INFO    = 0x2,
   WASM_DATA_SIZE      = 0x3,
   WASM_DATA_ALIGNMENT = 0x4,

lib/MC/WasmObjectWriter.cpp

@@ -287,8 +287,7 @@ private:
   void writeDataRelocSection();
   void writeLinkingMetaDataSection(
       ArrayRef<WasmDataSegment> Segments, uint32_t DataSize,
-      SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags,
-      Optional<uint32_t> StackPointerGlobal);
+      SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags);
 
   uint32_t getProvisionalValue(const WasmRelocationEntry &RelEntry);
   void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations,
@@ -929,18 +928,11 @@ void WasmObjectWriter::writeDataRelocSection() {
 
 void WasmObjectWriter::writeLinkingMetaDataSection(
     ArrayRef<WasmDataSegment> Segments, uint32_t DataSize,
-    SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags,
-    Optional<uint32_t> StackPointerGlobal) {
+    SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags) {
   SectionBookkeeping Section;
   startSection(Section, wasm::WASM_SEC_CUSTOM, "linking");
   SectionBookkeeping SubSection;
 
-  if (StackPointerGlobal.hasValue()) {
-    startSection(SubSection, wasm::WASM_STACK_POINTER);
-    encodeULEB128(StackPointerGlobal.getValue(), getStream()); // id
-    endSection(SubSection);
-  }
-
   if (SymbolFlags.size() != 0) {
     startSection(SubSection, wasm::WASM_SYMBOL_INFO);
     encodeULEB128(SymbolFlags.size(), getStream());
@@ -1011,8 +1003,6 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
   SmallPtrSet<const MCSymbolWasm *, 4> IsAddressTaken;
   unsigned NumFuncImports = 0;
   SmallVector<WasmDataSegment, 4> DataSegments;
-  Optional<StringRef> StackPointerGlobalName;
-  Optional<uint32_t> StackPointerGlobal;
   uint32_t DataSize = 0;
 
   // Populate the IsAddressTaken set.
@@ -1095,23 +1085,6 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
     }
   }
 
-  // In the special .stack_pointer section, we've encoded the stack pointer
-  // index.
-  MCSectionWasm *StackPtr =
-      Ctx.getWasmSection(".stack_pointer", SectionKind::getMetadata());
-  if (!StackPtr->getFragmentList().empty()) {
-    if (StackPtr->getFragmentList().size() != 1)
-      report_fatal_error("only one .stack_pointer fragment supported");
-    const MCFragment &Frag = *StackPtr->begin();
-    if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
-      report_fatal_error("only data supported in .stack_pointer");
-    const auto &DataFrag = cast<MCDataFragment>(Frag);
-    if (!DataFrag.getFixups().empty())
-      report_fatal_error("fixups not supported in .stack_pointer");
-    const SmallVectorImpl<char> &Contents = DataFrag.getContents();
-    StackPointerGlobalName = StringRef(Contents.data(), Contents.size());
-  }
-
   // Populate FunctionTypeIndices and Imports.
   for (const MCSymbol &S : Asm.symbols()) {
     const auto &WS = static_cast<const MCSymbolWasm &>(S);
@@ -1144,11 +1117,8 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
 
         // If this global is the stack pointer, make it mutable and remember it
         // so that we can emit metadata for it.
-        if (StackPointerGlobalName.hasValue() &&
-            WS.getName() == StackPointerGlobalName.getValue()) {
+        if (WS.getName() == "__stack_pointer")
           Import.IsMutable = true;
-          StackPointerGlobal = NumGlobalImports;
-        }
 
         ++NumGlobalImports;
       }
@@ -1338,8 +1308,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
   writeNameSection(Functions, Imports, NumFuncImports);
   writeCodeRelocSection();
   writeDataRelocSection();
-  writeLinkingMetaDataSection(DataSegments, DataSize, SymbolFlags,
-                              StackPointerGlobal);
+  writeLinkingMetaDataSection(DataSegments, DataSize, SymbolFlags);
 
   // TODO: Translate the .comment section to the output.
   // TODO: Translate debug sections to the output.

lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp

@@ -108,10 +108,6 @@ void WebAssemblyTargetAsmStreamer::emitGlobal(
   }
 }
 
-void WebAssemblyTargetAsmStreamer::emitStackPointer(MCSymbol *Symbol) {
-  OS << "\t.stack_pointer\t" << Symbol->getName() << '\n';
-}
-
 void WebAssemblyTargetAsmStreamer::emitEndFunc() { OS << "\t.endfunc\n"; }
 
 void WebAssemblyTargetAsmStreamer::emitIndirectFunctionType(
@@ -157,11 +153,6 @@ void WebAssemblyTargetELFStreamer::emitGlobal(
   llvm_unreachable(".globalvar encoding not yet implemented");
 }
 
-void WebAssemblyTargetELFStreamer::emitStackPointer(
-    MCSymbol *Symbol) {
-  llvm_unreachable(".stack_pointer encoding not yet implemented");
-}
-
 void WebAssemblyTargetELFStreamer::emitEndFunc() {
   Streamer.EmitIntValue(WebAssembly::End, 1);
 }
@@ -238,14 +229,6 @@ void WebAssemblyTargetWasmStreamer::emitGlobal(
   Streamer.PopSection();
 }
 
-void WebAssemblyTargetWasmStreamer::emitStackPointer(MCSymbol *Symbol) {
-  Streamer.PushSection();
-  Streamer.SwitchSection(Streamer.getContext().getWasmSection(
-      ".stack_pointer", SectionKind::getMetadata()));
-  Streamer.EmitBytes(Symbol->getName());
-  Streamer.PopSection();
-}
-
 void WebAssemblyTargetWasmStreamer::emitEndFunc() {
   llvm_unreachable(".end_func is not needed for direct wasm output");
 }

lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h

@@ -39,8 +39,6 @@ public:
   virtual void emitLocal(ArrayRef<MVT> Types) = 0;
   /// .globalvar
   virtual void emitGlobal(ArrayRef<wasm::Global> Globals) = 0;
-  /// .stack_pointer
-  virtual void emitStackPointer(MCSymbol *Symbol) = 0;
   /// .endfunc
   virtual void emitEndFunc() = 0;
   /// .functype
@@ -67,7 +65,6 @@ public:
   void emitResult(MCSymbol *Symbol, ArrayRef<MVT> Types) override;
   void emitLocal(ArrayRef<MVT> Types) override;
   void emitGlobal(ArrayRef<wasm::Global> Globals) override;
-  void emitStackPointer(MCSymbol *Symbol) override;
   void emitEndFunc() override;
   void emitIndirectFunctionType(MCSymbol *Symbol,
                                 SmallVectorImpl<MVT> &Params,
@@ -85,7 +82,6 @@ public:
   void emitResult(MCSymbol *Symbol, ArrayRef<MVT> Types) override;
   void emitLocal(ArrayRef<MVT> Types) override;
   void emitGlobal(ArrayRef<wasm::Global> Globals) override;
-  void emitStackPointer(MCSymbol *Symbol) override;
   void emitEndFunc() override;
   void emitIndirectFunctionType(MCSymbol *Symbol,
                                 SmallVectorImpl<MVT> &Params,
@@ -103,7 +99,6 @@ public:
   void emitResult(MCSymbol *Symbol, ArrayRef<MVT> Types) override;
   void emitLocal(ArrayRef<MVT> Types) override;
   void emitGlobal(ArrayRef<wasm::Global> Globals) override;
-  void emitStackPointer(MCSymbol *Symbol) override;
   void emitEndFunc() override;
   void emitIndirectFunctionType(MCSymbol *Symbol,
                                 SmallVectorImpl<MVT> &Params,

lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp

@@ -78,12 +78,6 @@ WebAssemblyTargetStreamer *WebAssemblyAsmPrinter::getTargetStreamer() {
 //===----------------------------------------------------------------------===//
 
 void WebAssemblyAsmPrinter::EmitEndOfAsmFile(Module &M) {
-  // Declare the stack pointer.
-  if (TM.getTargetTriple().isOSBinFormatWasm()) {
-    getTargetStreamer()->emitStackPointer(
-        GetExternalSymbolSymbol("__stack_pointer"));
-  }
-
   for (const auto &F : M) {
     // Emit function type info for all undefined functions
     if (F.isDeclarationForLinker() && !F.isIntrinsic()) {

test/CodeGen/WebAssembly/stack-alignment.ll

@@ -147,5 +147,3 @@ entry:
   call void @somefunc(i32* %static)
   ret void
 }
-
-; CHECK: .stack_pointer __stack_pointer