[WebAssembly] Remove DataSize from linking metadata section

Neither the linker nor the runtime need this information
anymore.  We were originally using this to model BSS size
but the plan is now to use the segment metadata to allow
for BSS segments.

Differential Revision: https://reviews.llvm.org/D41366

llvm-svn: 326267

include/llvm/BinaryFormat/Wasm.h

@@ -158,7 +158,6 @@ struct WasmFunctionName {
 };
 
 struct WasmLinkingData {
-  uint32_t DataSize;
   std::vector<WasmInitFunc> InitFunctions;
   std::vector<WasmSymbolInfo> SymbolTable;
 };
@@ -227,7 +226,6 @@ enum : unsigned {
 
 // Kind codes used in the custom "linking" section
 enum : unsigned {
-  WASM_DATA_SIZE      = 0x3,
   WASM_SEGMENT_INFO   = 0x5,
   WASM_INIT_FUNCS     = 0x6,
   WASM_COMDAT_INFO    = 0x7,

include/llvm/ObjectYAML/WasmYAML.h

@@ -195,7 +195,6 @@ struct LinkingSection : CustomSection {
     return C && C->Name == "linking";
   }
 
-  uint32_t DataSize;
   std::vector<SymbolInfo> SymbolTable;
   std::vector<SegmentInfo> SegmentInfos;
   std::vector<InitFunction> InitFunctions;

lib/MC/WasmObjectWriter.cpp

@@ -274,7 +274,7 @@ private:
   void writeCodeRelocSection();
   void writeDataRelocSection();
   void writeLinkingMetaDataSection(
-      uint32_t DataSize, ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
+      ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
       ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
       const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats);
 
@@ -862,7 +862,7 @@ void WasmObjectWriter::writeDataRelocSection() {
 }
 
 void WasmObjectWriter::writeLinkingMetaDataSection(
-    uint32_t DataSize, ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
+    ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
     ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
     const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats) {
   SectionBookkeeping Section;
@@ -897,12 +897,6 @@ void WasmObjectWriter::writeLinkingMetaDataSection(
     endSection(SubSection);
   }
 
-  if (DataSize > 0) {
-    startSection(SubSection, wasm::WASM_DATA_SIZE);
-    encodeULEB128(DataSize, getStream());
-    endSection(SubSection);
-  }
-
   if (DataSegments.size()) {
     startSection(SubSection, wasm::WASM_SEGMENT_INFO);
     encodeULEB128(DataSegments.size(), getStream());
@@ -1316,7 +1310,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
   writeDataSection();
   writeCodeRelocSection();
   writeDataRelocSection();
-  writeLinkingMetaDataSection(DataSize, SymbolInfos, InitFuncs, Comdats);
+  writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats);
 
   // TODO: Translate the .comment section to the output.
   // TODO: Translate debug sections to the output.

lib/Object/WasmObjectFile.cpp

@@ -197,8 +197,6 @@ static Error readSection(WasmSection &Section, const uint8_t *&Ptr,
 
 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
     : ObjectFile(Binary::ID_Wasm, Buffer) {
-  LinkingData.DataSize = 0;
-
   ErrorAsOutParameter ErrAsOutParam(&Err);
   Header.Magic = getData().substr(0, 4);
   if (Header.Magic != StringRef("\0asm", 4)) {
@@ -334,9 +332,6 @@ Error WasmObjectFile::parseLinkingSection(const uint8_t *Ptr,
       if (Error Err = parseLinkingSectionSymtab(Ptr, SubSectionEnd))
         return Err;
       break;
-    case wasm::WASM_DATA_SIZE:
-      LinkingData.DataSize = readVaruint32(Ptr);
-      break;
     case wasm::WASM_SEGMENT_INFO: {
       uint32_t Count = readVaruint32(Ptr);
       if (Count > DataSegments.size())

lib/ObjectYAML/WasmYAML.cpp

@@ -57,7 +57,6 @@ static void sectionMapping(IO &IO, WasmYAML::NameSection &Section) {
 static void sectionMapping(IO &IO, WasmYAML::LinkingSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapRequired("Name", Section.Name);
-  IO.mapRequired("DataSize", Section.DataSize);
   IO.mapOptional("SymbolTable", Section.SymbolTable);
   IO.mapOptional("SegmentInfo", Section.SegmentInfos);
   IO.mapOptional("InitFunctions", Section.InitFunctions);

test/MC/WebAssembly/array-fill.ll

@@ -14,7 +14,6 @@ target triple = "wasm32-unknown-unknown-wasm"
 
 ; CHECK:        - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        2
 ; CHECK-NEXT:     SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            DATA

test/MC/WebAssembly/bss.ll

@@ -37,7 +37,6 @@ target triple = "wasm32-unknown-unknown-wasm"
 ; CHECK-NEXT:         Content:         ''
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        8
 ; CHECK-NEXT:     SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            DATA

test/MC/WebAssembly/comdat.ll

@@ -75,7 +75,6 @@ define linkonce_odr i32 @sharedFn() #1 comdat($sharedComdat) {
 ; CHECK-NEXT:        Content:         '616263'
 ; CHECK-NEXT:  - Type:            CUSTOM
 ; CHECK-NEXT:    Name:            linking
-; CHECK-NEXT:    DataSize:        3
 ; CHECK-NEXT:    SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            FUNCTION

test/MC/WebAssembly/explicit-sections.ll

@@ -32,7 +32,6 @@ target triple = "wasm32-unknown-unknown-wasm"
 ; CHECK-NEXT:         Content:         '08000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        28
 ; CHECK-NEXT:     SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            DATA

test/MC/WebAssembly/global-ctor-dtor.ll

@@ -110,7 +110,6 @@ declare void @func3()
 ; CHECK-NEXT:         Content:         '01040000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        4
 ; CHECK-NEXT:     SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            FUNCTION

test/MC/WebAssembly/unnamed-data.ll

@@ -44,7 +44,6 @@ target triple = "wasm32-unknown-unknown-wasm"
 ; CHECK-NEXT:         Content:         '06000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        28
 ; CHECK-NEXT:     SymbolTable:      
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            DATA

test/MC/WebAssembly/visibility.ll

@@ -16,7 +16,6 @@ entry:
 
 ; CHECK:        - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        0
 ; CHECK-NEXT:     SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            FUNCTION

test/MC/WebAssembly/weak-alias.ll

@@ -138,7 +138,6 @@ entry:
 ; CHECK-NEXT:         Content:         '01000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        20
 ; CHECK-NEXT:     SymbolTable:      
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            FUNCTION

test/MC/WebAssembly/weak.ll

@@ -22,7 +22,6 @@ entry:
 
 ; CHECK:        - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     DataSize:        0
 ; CHECK-NEXT:     SymbolTable:      
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            DATA

test/Object/obj2yaml.test

@@ -651,7 +651,6 @@ WASM-NEXT: FileHeader:
 WASM-NEXT:   Version:         0x00000001
 WASM:        - Type:            CUSTOM
 WASM-NEXT:     Name:            linking
-WASM-NEXT:     DataSize:        20
 WASM-NEXT:     SymbolTable:
 WASM-NEXT:       - Index:           0
 WASM-NEXT:         Kind:            FUNCTION

test/ObjectYAML/wasm/linking_section.yaml

@@ -29,7 +29,6 @@ Sections:
         Content:         '11110000'
   - Type:            CUSTOM
     Name:            linking
-    DataSize:        999
     SymbolTable:
       - Index:           0
         Kind:            FUNCTION
@@ -51,7 +50,6 @@ Sections:
 ...
 # CHECK:       - Type:            CUSTOM
 # CHECK-NEXT:    Name:            linking
-# CHECK-NEXT:    DataSize:        999
 # CHECK-NEXT:    SymbolTable:
 # CHECK-NEXT:      - Index:           0
 # CHECK-NEXT:        Kind:            FUNCTION

test/ObjectYAML/wasm/weak_symbols.yaml

@@ -36,7 +36,6 @@ Sections:
         Body:            00
   - Type:            CUSTOM
     Name:            linking
-    DataSize:        10
     SymbolTable:
       - Index:           0
         Kind:            FUNCTION
@@ -63,7 +62,6 @@ Sections:
 # CHECK:         Index:           0
 # CHECK:   - Type:            CUSTOM
 # CHECK:     Name:            linking
-# CHECK:     DataSize:        10
 # CHECK:     SymbolTable:
 # CHECK:      - Index:           0
 # CHECK:        Kind:            FUNCTION

test/tools/llvm-nm/wasm/exports.yaml

@@ -37,7 +37,6 @@ Sections:
         Content:         '616263'
   - Type:            CUSTOM
     Name:            linking
-    DataSize:        3
     SymbolTable:
        - Index:           0
          Kind:            FUNCTION

test/tools/llvm-nm/wasm/imports.yaml

@@ -25,7 +25,6 @@ Sections:
         GlobalMutable:   false
   - Type:            CUSTOM
     Name:            linking
-    DataSize:        3
     SymbolTable:
        - Index:           0
          Kind:            FUNCTION

test/tools/llvm-nm/wasm/weak-symbols.yaml

@@ -48,7 +48,6 @@ Sections:
         Content:         '616263'
   - Type:            CUSTOM
     Name:            linking
-    DataSize:        3
     SymbolTable:
        - Index:           0
          Kind:            DATA

test/tools/llvm-readobj/sections.test

@@ -537,6 +537,5 @@ WASM-NEXT:     Type: CUSTOM (0x0)
 WASM-NEXT:     Size: 72
 WASM-NEXT:     Offset: 220
 WASM-NEXT:     Name: linking
-WASM-NEXT:     DataSize: 13
 WASM-NEXT:   }
 WASM-NEXT: ]

tools/llvm-readobj/WasmDumper.cpp

@@ -153,7 +153,6 @@ void WasmDumper::printSections() {
       W.printString("Name", WasmSec.Name);
       if (WasmSec.Name == "linking") {
         const wasm::WasmLinkingData &LinkingData = Obj->linkingData();
-        W.printNumber("DataSize", LinkingData.DataSize);
         if (!LinkingData.InitFunctions.empty()) {
           ListScope Group(W, "InitFunctions");
           for (const wasm::WasmInitFunc &F: LinkingData.InitFunctions)

tools/obj2yaml/wasm2yaml.cpp

@@ -109,7 +109,6 @@ std::unique_ptr<WasmYAML::CustomSection> WasmDumper::dumpCustomSection(const Was
       }
       LinkingSec->SymbolTable.emplace_back(Info);
     }
-    LinkingSec->DataSize = Obj.linkingData().DataSize;
     for (const wasm::WasmInitFunc &Func : Obj.linkingData().InitFunctions) {
       WasmYAML::InitFunction F{Func.Priority, Func.Symbol};
       LinkingSec->InitFunctions.emplace_back(F);

tools/yaml2obj/yaml2wasm.cpp

@@ -136,11 +136,6 @@ int WasmWriter::writeSectionContent(raw_ostream &OS, WasmYAML::LinkingSection &S
 
   SubSectionWriter SubSection(OS);
 
-  // DATA_SIZE subsection
-  encodeULEB128(wasm::WASM_DATA_SIZE, OS);
-  encodeULEB128(Section.DataSize, SubSection.GetStream());
-  SubSection.Done();
-
   // SYMBOL_TABLE subsection
   if (Section.SymbolTable.size()) {
     encodeULEB128(wasm::WASM_SYMBOL_TABLE, OS);