Minimize patch

clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp

@@ -332,18 +332,27 @@ ObjectFilePCHContainerReader::ExtractPCH(llvm::MemoryBufferRef Buffer) const {
   if (OFOrErr) {
     auto &OF = OFOrErr.get();
     bool IsCOFF = isa<llvm::object::COFFObjectFile>(*OF);
-    // Find the clang AST section in the container.
-    for (auto &Section : OF->sections()) {
-      StringRef Name;
-      Section.getName(Name);
-      if ((!IsCOFF && Name == "__clangast") || (IsCOFF && Name == "clangast")) {
-        if (Expected<StringRef> E = Section.getContents())
-          return *E;
-        else {
-          handleAllErrors(E.takeError(), [&](const llvm::ErrorInfoBase &EIB) {
-            EIB.log(llvm::errs());
-          });
-          return "";
+    StringRef SectionName = IsCOFF ? "clangast" : "__clangast";
+
+    if (const auto &WasmOF = llvm::unique_dyn_cast<llvm::object::WasmObjectFile>(OF)) {
+      for (auto &Segment : WasmOF->dataSegments()) {
+        if (Segment.Data.Name != SectionName) continue;
+        return llvm::toStringRef(Segment.Data.Content);
+      }
+    } else {
+      // Find the clang AST section in the container.
+      for (auto &Section : OF->sections()) {
+        StringRef Name;
+        Section.getName(Name);
+        if (Name == SectionName) {
+          if (Expected<StringRef> E = Section.getContents())
+            return *E;
+          else {
+            handleAllErrors(E.takeError(), [&](const llvm::ErrorInfoBase &EIB) {
+              EIB.log(llvm::errs());
+            });
+            return "";
+          }
         }
       }
     }

clang/lib/Driver/ToolChains/Clang.cpp

@@ -448,9 +448,6 @@ static void addExceptionArgs(const ArgList &Args, types::ID InputType,
     // Disable C++ EH by default on XCore and PS4.
     bool CXXExceptionsEnabled =
         Triple.getArch() != llvm::Triple::xcore && !Triple.isPS4CPU();
-    // WebAssembly: no exception handling on WASI
-    if (Triple.isOSBinFormatWasm())
-      CXXExceptionsEnabled = false;
     Arg *ExceptionArg = Args.getLastArg(
         options::OPT_fcxx_exceptions, options::OPT_fno_cxx_exceptions,
         options::OPT_fexceptions, options::OPT_fno_exceptions);

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -1682,10 +1682,6 @@ static SectionKind getWasmKindForNamedSection(StringRef Name, SectionKind K) {
   if (K.isText())
     return SectionKind::getText();
 
-  // Clang precompiled header data isn't needed at runtime; use custom section
-  if (Name == "__clangast")
-    return SectionKind::getMetadata();
-
   // Otherwise, ignore whatever section type the generic impl detected and use
   // a plain data section.
   return SectionKind::getData();

llvm/lib/MC/WasmObjectWriter.cpp

@@ -372,15 +372,7 @@ void WasmObjectWriter::startCustomSection(SectionBookkeeping &Section,
   Section.PayloadOffset = W.OS.tell();
 
   // Custom sections in wasm also have a string identifier.
-  if (Name != "__clangast") {
-    writeString(Name);
-  } else {
-    // pad section start to nearest 4 bytes for Clang PCH
-    uint64_t MinLength = Section.PayloadOffset + 5ULL /* min ULEB128 length */ + Name.size();
-    uint64_t RoundedUpLength = (MinLength + 3ULL) & ~3ULL;
-    encodeULEB128(Name.size(), W.OS, 5 + (RoundedUpLength - MinLength));
-    W.OS << Name;
-  }
+  writeString(Name);
 
   // The position where the custom section starts.
   Section.ContentsOffset = W.OS.tell();
@@ -493,9 +485,6 @@ void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
 
   if (SymA && SymA->isVariable()) {
     const MCExpr *Expr = SymA->getVariableValue();
-    if (Expr->getKind() != MCExpr::SymbolRef) {
-      fprintf(stderr, "The expr type is %d\n", (int)Expr->getKind());
-    }
     const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
     if (Inner && Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
       llvm_unreachable("weakref used in reloc not yet implemented");
@@ -581,7 +570,6 @@ static const MCSymbolWasm *resolveSymbol(const MCSymbolWasm &Symbol) {
   while (Ret->isVariable()) {
     const MCExpr *Expr = Ret->getVariableValue();
     if (Expr->getKind() == MCExpr::Binary) {
-      fprintf(stderr, "The expr type is %d\n", (int)Expr->getKind());
       Expr = pullSymbol(Expr);
       if (!Expr) {
         llvm_unreachable("can't find a symbol in this mess\n");
@@ -1081,16 +1069,8 @@ void WasmObjectWriter::writeCustomSection(WasmCustomSection &CustomSection,
   auto *Sec = CustomSection.Section;
   startCustomSection(Section, CustomSection.Name);
 
-    if (CustomSection.Name == "__clangast") {
-      // pad to nearest 4 bytes
-      uint64_t RoundedUp = (Section.ContentsOffset + 3ULL) & ~3ULL;
-      for (uint64_t Count = 0; Count < RoundedUp - Section.ContentsOffset; Count++) {
-        W.OS << char(0);
-      }
-    }
-
-    Sec->setSectionOffset(W.OS.tell() - Section.ContentsOffset);
-    Asm.writeSectionData(W.OS, Sec, Layout);
+  Sec->setSectionOffset(W.OS.tell() - Section.ContentsOffset);
+  Asm.writeSectionData(W.OS, Sec, Layout);
 
   CustomSection.OutputContentsOffset = Section.ContentsOffset;
   CustomSection.OutputIndex = Section.Index;
@@ -1171,29 +1151,9 @@ static bool isInSymtab(const MCSymbolWasm &Sym) {
   if (Sym.isSection())
     return false;
 
-  // Clang's precompiled headers are in a separate custom section
-  if (Sym.getName() == "__clang_ast")
-    return false;
-
   return true;
 }
 
-// SwiftWasm: takes a MCSymbolWasm that's an alias expression of the form
-// ((targetSymbol + constantA) - constantB) + constantC...)
-// return the final offset from targetSymbol.
-// if no offset, returns 0.
-static int64_t getAliasedSymbolOffset(const MCSymbolWasm &Symbol,
-                                      const MCAsmLayout &Layout) {
-  if (!Symbol.isVariable())
-    return 0;
-  const MCExpr *Expr = Symbol.getVariableValue();
-  MCValue Res;
-  if (!Expr->evaluateAsRelocatable(Res, &Layout, nullptr)) {
-    report_fatal_error("Can't evaluate alias symbol expression");
-  }
-  return Res.getConstant();
-}
-
 uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
                                        const MCAsmLayout &Layout) {
   uint64_t StartOffset = W.OS.tell();
@@ -1424,10 +1384,6 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
       LLVM_DEBUG(dbgs() << "  -> function index: " << Index << "\n");
 
     } else if (WS.isData()) {
-      if (WS.getName() == "__clang_ast")
-        continue;
-      if (WS.isTemporary() && !WS.getSize())
-        continue;
       if (!isInSymtab(WS))
         continue;
 
@@ -1503,9 +1459,6 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
     // Find the target symbol of this weak alias and export that index
     const auto &WS = static_cast<const MCSymbolWasm &>(S);
     const MCSymbolWasm *ResolvedSym = resolveSymbol(WS);
-    if (!ResolvedSym) {
-      continue;
-    }
     LLVM_DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym
                       << "'\n");
 
@@ -1517,16 +1470,8 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
       LLVM_DEBUG(dbgs() << "  -> index:" << WasmIndex << "\n");
     } else if (ResolvedSym->isData()) {
       assert(DataLocations.count(ResolvedSym) > 0);
-      // SwiftWasm: hack: grab the offset
-      // Swift has aliases of the form
-      // alias = ((symbol + constant) - constant)
-      // so we need to evaluate the constants here using MCExpr
-      // there's probably a proper way to do this.
-      int64_t Offset = getAliasedSymbolOffset(WS, Layout);
-      wasm::WasmDataReference Ref =
+      const wasm::WasmDataReference &Ref =
           DataLocations.find(ResolvedSym)->second;
-      Ref.Offset += Offset;
-      Ref.Size -= Offset;
       DataLocations[&WS] = Ref;
       LLVM_DEBUG(dbgs() << "  -> index:" << Ref.Segment << "\n");
     } else {