[WebAssembly] Support for new per-segment linking metadata

test/wasm/call-indirect.ll

 ; CHECK-NEXT:         MemoryIndex:      0
 ; CHECK-NEXT:         Offset:          
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           1028
 ; CHECK-NEXT:         Content:         '02000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        8
-; CHECK-NEXT:     DataAlignment:   0
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            name
 ; CHECK-NEXT:     FunctionNames:   
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            bar
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Name:            call_bar_indirect
 ; CHECK-NEXT:       - Index:           2
 ; CHECK-NEXT:         Name:            foo
 ; CHECK-NEXT:       - Index:           3
 ; CHECK-NEXT:         Name:            _start

test/wasm/data-layout.ll

 ; CHECK-NEXT:         Offset:
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           1052
 ; CHECK-NEXT:         Content:         68656C6C6F0A00
 
 ; CHECK:       - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        35
-; CHECK-NEXT:     DataAlignment:   0

test/wasm/local-symbols.ll

 ; CHECK-NEXT:         MemoryIndex:     0
 ; CHECK-NEXT:         Offset:          
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           1028
 ; CHECK-NEXT:         Content:         '03000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        8
-; CHECK-NEXT:     DataAlignment:   0
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            name
 ; CHECK-NEXT:     FunctionNames:   
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Name:            _start
 ; CHECK-NEXT: ...
 

test/wasm/relocatable.ll

 ; CHECK-NEXT:         MemoryIndex:     0
 ; CHECK-NEXT:         Offset:          
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           12
 ; CHECK-NEXT:         Content:         '01000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        16
-; CHECK-NEXT:     DataAlignment:   4
+; CHECK-NEXT:     SegmentInfo:     
+; CHECK-NEXT:       - Index:           0
+; CHECK-NEXT:         Name:            .rodata.hello_str
+; CHECK-NEXT:         Alignment:       1
+; CHECK-NEXT:         Flags:           0
+; CHECK-NEXT:       - Index:           1
+; CHECK-NEXT:         Name:            .data.func_addr1
+; CHECK-NEXT:         Alignment:       4
+; CHECK-NEXT:         Flags:           0
+; CHECK-NEXT:       - Index:           2
+; CHECK-NEXT:         Name:            .data.func_addr2
+; CHECK-NEXT:         Alignment:       4
+; CHECK-NEXT:         Flags:           0
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            name
 ; CHECK-NEXT:     FunctionNames:   
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            puts
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Name:            foo_import
 ; CHECK-NEXT:       - Index:           2
 ; CHECK-NEXT:         Name:            hello
 ; CHECK-NEXT:       - Index:           3
 ; CHECK-NEXT:         Name:            my_func
 ; CHECK-NEXT: ...

test/wasm/weak-alias-overide.ll

 ; CHECK-NEXT:         Body:            1080808080001A0B
 ; CHECK-NEXT:       - Locals:          
 ; CHECK-NEXT:         Body:            41000B
 ; CHECK-NEXT:       - Locals:          
 ; CHECK-NEXT:         Body:            1080808080000B
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        0
-; CHECK-NEXT:     DataAlignment:   0
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            name
 ; CHECK-NEXT:     FunctionNames:   
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            bar
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Name:            _start
 ; CHECK-NEXT:       - Index:           2
 ; CHECK-NEXT:         Name:            foo
 ; CHECK-NEXT:       - Index:           3
 ; CHECK-NEXT:         Name:            call_bar
 ; CHECK-NEXT: ...

test/wasm/weak-alias.ll

 ; CHECK-NEXT:         Body:            1081808080000B
 ; CHECK-NEXT:       - Locals:          
 ; CHECK-NEXT:         Body:            41000B
 ; CHECK-NEXT:       - Locals:          
 ; CHECK-NEXT:         Body:            1081808080000B
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        0
-; CHECK-NEXT:     DataAlignment:   0
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            name
 ; CHECK-NEXT:     FunctionNames:   
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            _start
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Name:            foo
 ; CHECK-NEXT:       - Index:           2
 ; CHECK-NEXT:         Name:            call_bar
 ; CHECK-NEXT: ...

test/wasm/weak-external.ll

 ; CHECK-NEXT:     Functions:
 ; CHECK-NEXT:       - Locals:
 ; CHECK-NEXT:         Body:            4181808080000B
 ; CHECK-NEXT:       - Locals:
 ; CHECK-NEXT:         Body:            4100280280808080000B
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        0
-; CHECK-NEXT:     DataAlignment:   0
 ; CHECK-NEXT: ...

wasm/InputFiles.h

public:
 
   size_t NumFunctionImports() const { return FunctionImports; }
   size_t NumGlobalImports() const { return GlobalImports; }
 
   int32_t FunctionIndexOffset = 0;
   int32_t GlobalIndexOffset = 0;
   int32_t TableIndexOffset = 0;
   uint32_t DataOffset = 0;
+  uint32_t DataAlignment = 0;
   const WasmSection *CodeSection = nullptr;
   const WasmSection *DataSection = nullptr;
 
   std::vector<uint32_t> TypeMap;
 
   const std::vector<Symbol *> &getSymbols() { return Symbols; }
 
 private:

wasm/InputFiles.cpp

void ObjectFile::parse() {
   for (const SectionRef &Sec : WasmObj->sections()) {
     const WasmSection &Section = WasmObj->getWasmSection(Sec);
     if (Section.Type == WASM_SEC_CODE)
       CodeSection = &Section;
     else if (Section.Type == WASM_SEC_DATA)
       DataSection = &Section;
   }
 
+  for (const WasmSegment &Segment : WasmObj->dataSegments())
+    DataAlignment = std::max(DataAlignment, Segment.Data.Alignment);
+
   initializeSymbols();
 }
 
 void ObjectFile::initializeSymbols() {
   Symbols.reserve(WasmObj->getNumberOfSymbols());
 
   for (const WasmImport &Import : WasmObj->imports()) {
     switch (Import.Kind) {

wasm/Writer.cpp

private:
   void createLinkingSection();
   void createNameSection();
 
   void writeHeader();
   void writeSections();
 
   uint64_t FileSize = 0;
   uint32_t DataSize = 0;
-  uint32_t DataAlignment = 1;
   uint32_t NumFunctions = 0;
   uint32_t NumGlobals = 0;
   uint32_t NumMemoryPages = 0;
   uint32_t NumTableElems = 0;
   uint32_t NumElements = 0;
   uint32_t NumDataSegments = 0;
   uint32_t InitialTableOffset = 0;
 
SyntheticSection *Section =
       createSyntheticSection(WASM_SEC_CUSTOM, "linking");
   raw_ostream &OS = Section->getStream();
 
   SubSection DataSizeSubSection(WASM_DATA_SIZE);
   writeUleb128(DataSizeSubSection.getStream(), DataSize, "data size");
   DataSizeSubSection.finalizeContents();
   DataSizeSubSection.writeToStream(OS);
 
-  if (Config->Relocatable) {
-    SubSection DataAlignSubSection(WASM_DATA_ALIGNMENT);
-    writeUleb128(DataAlignSubSection.getStream(), DataAlignment, "data align");
-    DataAlignSubSection.finalizeContents();
-    DataAlignSubSection.writeToStream(OS);
+  if (NumDataSegments && Config->Relocatable) {
+    SubSection SubSection(WASM_SEGMENT_INFO);
+    writeUleb128(SubSection.getStream(), NumDataSegments, "num data segments");
+    for (ObjectFile *File : Symtab->ObjectFiles) {
+      for (const object::WasmSegment &S: File->getWasmObj()->dataSegments()) {
+        writeStr(SubSection.getStream(), S.Data.Name, "segment name");
+        writeUleb128(SubSection.getStream(), S.Data.Alignment, "alignment");
+        writeUleb128(SubSection.getStream(), S.Data.Flags, "flags");
+      }
+    }
+    SubSection.finalizeContents();
+    SubSection.writeToStream(OS);
   }
 }
 
 // Create the custom "name" section containing debug symbol names.
 void Writer::createNameSection() {
   SyntheticSection *Section = createSyntheticSection(WASM_SEC_CUSTOM, "name");
 
   size_t FunctionNameCount = 0;

 void Writer::layoutMemory() {
   uint32_t MemoryPtr = 0;
   if (!Config->Relocatable) {
     MemoryPtr = Config->GlobalBase;
     debugPrint("mem: global base = %d\n", Config->GlobalBase);
   }
 
   // Static data from input object files comes first
-  MemoryPtr = alignTo(MemoryPtr, DataAlignment);
   for (ObjectFile *File : Symtab->ObjectFiles) {
     const WasmObjectFile *WasmFile = File->getWasmObj();
     uint32_t Size = WasmFile->linkingData().DataSize;
     if (Size) {
-      MemoryPtr = alignTo(MemoryPtr, WasmFile->linkingData().DataAlignment);
+      MemoryPtr = alignTo(MemoryPtr, File->DataAlignment);
       debugPrint("mem: [%s] offset=%#x size=%d\n",
                  File->getName().str().c_str(), File->DataOffset, Size);
       File->DataOffset = MemoryPtr;
       MemoryPtr += Size;
     } else {
       debugPrint("mem: [%s] no data\n", File->getName().str().c_str());
     }
   }

 
 void Writer::calculateOffsets() {
   NumGlobals = Config->SyntheticGlobals.size();
   NumTableElems = InitialTableOffset;
 
   for (ObjectFile *File : Symtab->ObjectFiles) {
     const WasmObjectFile *WasmFile = File->getWasmObj();
 
-    DataAlignment =
-        std::max(DataAlignment, WasmFile->linkingData().DataAlignment);
-
     // Function Index
     File->FunctionIndexOffset =
         FunctionImports.size() - File->NumFunctionImports() + NumFunctions;
     NumFunctions += WasmFile->functions().size();
 
     // Global Index
     if (Config->Relocatable || Config->EmitRelocs) {
       File->GlobalIndexOffset =