[WebAssembly] Change prefix on data segment flags to WASM_DATA_SEGMENT

[wingo]

Summary

Element sections will also need flags, so we shouldn't squat the
WASM_SEGMENT namespace.

Depends on D90948.

[sbc100]

I wonder though if we can share the same set of flags for both? Don't table elem and data elem segment share the same set of flags?

[wingo]

Rebase

[wingo]

Rebase

[wingo]

This one is ready for review; a simple renaming to prepare for WASM_ELEMENT_SEGMENT flags in D92321. NFC.

[sbc100]

llvm/include/llvm/BinaryFormat/Wasm.h

151

Shall we move the comments onto the above line rather than splitting like this?

[wingo]

Reformat comments on WasmDataSegment

llvm/include/llvm/BinaryFormat/Wasm.h

151

Done, tx. (I love clang-format but i also get to blame it in this case!)

lld/wasm/OutputSections.cpp

void DataSection::finalizeContents() {
   raw_string_ostream os(dataSectionHeader);
   unsigned segmentCount =
       std::count_if(segments.begin(), segments.end(),
                     [](OutputSegment *segment) { return !segment->isBss; });
 
 #ifndef NDEBUG
   unsigned activeCount = std::count_if(
       segments.begin(), segments.end(), [](OutputSegment *segment) {
-        return (segment->initFlags & WASM_SEGMENT_IS_PASSIVE) == 0;
+        return (segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0;
       });
 #endif
 
   assert((!config->isPic || activeCount <= 1) &&
          "Currenly only a single data segment is supported in PIC mode");
 
   writeUleb128(os, segmentCount, "data segment count");
   os.flush();
   bodySize = dataSectionHeader.size();
 
   for (OutputSegment *segment : segments) {
     if (segment->isBss)
       continue;
     raw_string_ostream os(segment->header);
     writeUleb128(os, segment->initFlags, "init flags");
-    if (segment->initFlags & WASM_SEGMENT_HAS_MEMINDEX)
+    if (segment->initFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX)
       writeUleb128(os, 0, "memory index");
-    if ((segment->initFlags & WASM_SEGMENT_IS_PASSIVE) == 0) {
+    if ((segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
       WasmInitExpr initExpr;
       if (config->isPic) {
         initExpr.Opcode = WASM_OPCODE_GLOBAL_GET;
         initExpr.Value.Global = WasmSym::memoryBase->getGlobalIndex();
       } else {
         // FIXME(wvo): I64?
         initExpr.Opcode = WASM_OPCODE_I32_CONST;
         initExpr.Value.Int32 = segment->startVA;

lld/wasm/Writer.cpp

for (InputSegment *segment : file->segments) {
       if (!segment->live)
         continue;
       StringRef name = getOutputDataSegmentName(segment->getName());
       OutputSegment *&s = segmentMap[name];
       if (s == nullptr) {
         LLVM_DEBUG(dbgs() << "new segment: " << name << "\n");
         s = make<OutputSegment>(name);
         if (config->sharedMemory)
-          s->initFlags = WASM_SEGMENT_IS_PASSIVE;
+          s->initFlags = WASM_DATA_SEGMENT_IS_PASSIVE;
         // Exported memories are guaranteed to be zero-initialized, so no need
         // to emit data segments for bss sections.
         // TODO: consider initializing bss sections with memory.fill
         // instructions when memory is imported and bulk-memory is available.
         if (!config->importMemory && !config->relocatable &&
             name.startswith(".bss"))
           s->isBss = true;
         segments.push_back(s);
std::string functionBody;
     writeUleb128(os, bodyContent.size(), "function size");
     os << bodyContent;
   }
   ArrayRef<uint8_t> body = arrayRefFromStringRef(saver.save(functionBody));
   cast<SyntheticFunction>(func->function)->setBody(body);
 }
 
 bool Writer::needsPassiveInitialization(const OutputSegment *segment) {
-  return segment->initFlags & WASM_SEGMENT_IS_PASSIVE &&
+  return segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE &&
          segment->name != ".tdata" && !segment->isBss;
 }
 
 bool Writer::hasPassiveInitializedSegments() {
   return std::find_if(segments.begin(), segments.end(),
                       [this](const OutputSegment *s) {
                         return this->needsPassiveInitialization(s);
                       }) != segments.end();

llvm/include/llvm/BinaryFormat/Wasm.h

struct WasmFunction {
   Optional<StringRef> ExportName; // from the "export" section
   StringRef SymbolName; // from the "linking" section
   StringRef DebugName;  // from the "name" section
   uint32_t Comdat;      // from the "comdat info" section
 };
 
 struct WasmDataSegment {
   uint32_t InitFlags;
-  uint32_t MemoryIndex; // present if InitFlags & WASM_SEGMENT_HAS_MEMINDEX
-  WasmInitExpr Offset; // present if InitFlags & WASM_SEGMENT_IS_PASSIVE == 0
+  // Present if InitFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX.
+  uint32_t MemoryIndex;
+  // Present if InitFlags & WASM_DATA_SEGMENT_IS_PASSIVE == 0.
+  WasmInitExpr Offset;
+
   ArrayRef<uint8_t> Content;
   StringRef Name; // from the "segment info" section
   uint32_t Alignment;
   uint32_t LinkerFlags;
   uint32_t Comdat; // from the "comdat info" section
 };
 
 struct WasmElemSegment {

 enum : unsigned {
   WASM_LIMITS_FLAG_NONE = 0x0,
   WASM_LIMITS_FLAG_HAS_MAX = 0x1,
   WASM_LIMITS_FLAG_IS_SHARED = 0x2,
   WASM_LIMITS_FLAG_IS_64 = 0x4,
 };
 
 enum : unsigned {
-  WASM_SEGMENT_IS_PASSIVE = 0x01,
-  WASM_SEGMENT_HAS_MEMINDEX = 0x02,
+  WASM_DATA_SEGMENT_IS_PASSIVE = 0x01,
+  WASM_DATA_SEGMENT_HAS_MEMINDEX = 0x02,
 };
 
 // Feature policy prefixes used in the custom "target_features" section
 enum : uint8_t {
   WASM_FEATURE_PREFIX_USED = '+',
   WASM_FEATURE_PREFIX_REQUIRED = '=',
   WASM_FEATURE_PREFIX_DISALLOWED = '-',
 };

llvm/lib/MC/WasmObjectWriter.cpp

uint32_t WasmObjectWriter::writeDataSection(const MCAsmLayout &Layout) {
 
   SectionBookkeeping Section;
   startSection(Section, wasm::WASM_SEC_DATA);
 
   encodeULEB128(DataSegments.size(), W->OS); // count
 
   for (const WasmDataSegment &Segment : DataSegments) {
     encodeULEB128(Segment.InitFlags, W->OS); // flags
-    if (Segment.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX)
+    if (Segment.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX)
       encodeULEB128(0, W->OS); // memory index
-    if ((Segment.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) {
+    if ((Segment.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
       W->OS << char(Segment.Offset > INT32_MAX ? wasm::WASM_OPCODE_I64_CONST
                                                : wasm::WASM_OPCODE_I32_CONST);
       encodeSLEB128(Segment.Offset, W->OS); // offset
       W->OS << char(wasm::WASM_OPCODE_END);
     }
     encodeULEB128(Segment.Data.size(), W->OS); // size
     Segment.Section->setSectionOffset(W->OS.tell() - Section.ContentsOffset);
     W->OS << Segment.Data; // data
if (Section.getKind().isText())
       continue;
 
     if (Section.isWasmData()) {
       uint32_t SegmentIndex = DataSegments.size();
       DataSize = alignTo(DataSize, Section.getAlignment());
       DataSegments.emplace_back();
       WasmDataSegment &Segment = DataSegments.back();
       Segment.Name = SectionName;
-      Segment.InitFlags =
-          Section.getPassive() ? (uint32_t)wasm::WASM_SEGMENT_IS_PASSIVE : 0;
+      Segment.InitFlags = Section.getPassive()
+                              ? (uint32_t)wasm::WASM_DATA_SEGMENT_IS_PASSIVE
+                              : 0;
       Segment.Offset = DataSize;
       Segment.Section = &Section;
       addData(Segment.Data, Section);
       Segment.Alignment = Log2_32(Section.getAlignment());
       Segment.LinkerFlags = 0;
       DataSize += Segment.Data.size();
       Section.setSegmentIndex(SegmentIndex);
 

llvm/lib/Object/WasmObjectFile.cpp

Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
   uint32_t Count = readVaruint32(Ctx);
   if (DataCount && Count != DataCount.getValue())
     return make_error<GenericBinaryError>(
         "Number of data segments does not match DataCount section");
   DataSegments.reserve(Count);
   while (Count--) {
     WasmSegment Segment;
     Segment.Data.InitFlags = readVaruint32(Ctx);
-    Segment.Data.MemoryIndex = (Segment.Data.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX)
-                               ? readVaruint32(Ctx) : 0;
-    if ((Segment.Data.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) {
+    Segment.Data.MemoryIndex =
+        (Segment.Data.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX)
+            ? readVaruint32(Ctx)
+            : 0;
+    if ((Segment.Data.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
       if (Error Err = readInitExpr(Segment.Data.Offset, Ctx))
         return Err;
     } else {
       Segment.Data.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
       Segment.Data.Offset.Value.Int32 = 0;
     }
     uint32_t Size = readVaruint32(Ctx);
     if (Size > (size_t)(Ctx.End - Ctx.Ptr))

llvm/lib/ObjectYAML/WasmEmitter.cpp

void WasmWriter::writeSectionContent(raw_ostream &OS,
   }
 }
 
 void WasmWriter::writeSectionContent(raw_ostream &OS,
                                      WasmYAML::DataSection &Section) {
   encodeULEB128(Section.Segments.size(), OS);
   for (auto &Segment : Section.Segments) {
     encodeULEB128(Segment.InitFlags, OS);
-    if (Segment.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX)
+    if (Segment.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX)
       encodeULEB128(Segment.MemoryIndex, OS);
-    if ((Segment.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0)
+    if ((Segment.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0)
       writeInitExpr(OS, Segment.Offset);
     encodeULEB128(Segment.Content.binary_size(), OS);
     Segment.Content.writeAsBinary(OS);
   }
 }
 
 void WasmWriter::writeSectionContent(raw_ostream &OS,
                                      WasmYAML::DataCountSection &Section) {

llvm/lib/ObjectYAML/WasmYAML.cpp

void MappingTraits<wasm::WasmInitExpr>::mapping(IO &IO,
   }
   }
 }
 
 void MappingTraits<WasmYAML::DataSegment>::mapping(
     IO &IO, WasmYAML::DataSegment &Segment) {
   IO.mapOptional("SectionOffset", Segment.SectionOffset);
   IO.mapRequired("InitFlags", Segment.InitFlags);
-  if (Segment.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX) {
+  if (Segment.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX) {
     IO.mapRequired("MemoryIndex", Segment.MemoryIndex);
   } else {
     Segment.MemoryIndex = 0;
   }
-  if ((Segment.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) {
+  if ((Segment.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
     IO.mapRequired("Offset", Segment.Offset);
   } else {
     Segment.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
     Segment.Offset.Value.Int32 = 0;
   }
   IO.mapRequired("Content", Segment.Content);
 }