3 files changed, 31 insertions, 10 deletions
diff --git a/third_party/llvm-project/DWARFEmitter.cpp b/third_party/llvm-project/DWARFEmitter.cpp
index 92efcdfa0..6e4ee6119 100644
--- a/third_party/llvm-project/DWARFEmitter.cpp
+++ b/third_party/llvm-project/DWARFEmitter.cpp
@@ -78,6 +78,10 @@ void DWARFYAML::EmitDebugStr(raw_ostream &OS, const DWARFYAML::Data &DI) {
 void DWARFYAML::EmitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (auto AbbrevDecl : DI.AbbrevDecls) {
     encodeULEB128(AbbrevDecl.Code, OS);
+    // XXX BINARYEN This is a terminator.
+    if (!AbbrevDecl.Code) {
+      continue;
+    }
     encodeULEB128(AbbrevDecl.Tag, OS);
     OS.write(AbbrevDecl.Children);
     for (auto Attr : AbbrevDecl.Attributes) {
@@ -89,10 +93,6 @@ void DWARFYAML::EmitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {
     encodeULEB128(0, OS);
     encodeULEB128(0, OS);
   }
-  // XXX BINARYEN: end the list with a zero. LLVM works with or without this,
-  //               but other decoders may error. See
-  //               https://bugs.llvm.org/show_bug.cgi?id=44511
-  writeInteger((uint8_t)0, OS, true /* isLittleEndian */);
 }
 
 void DWARFYAML::EmitDebugAranges(raw_ostream &OS, const DWARFYAML::Data &DI) {
diff --git a/third_party/llvm-project/DWARFVisitor.cpp b/third_party/llvm-project/DWARFVisitor.cpp
index 05c4194e3..44bb33b47 100644
--- a/third_party/llvm-project/DWARFVisitor.cpp
+++ b/third_party/llvm-project/DWARFVisitor.cpp
@@ -44,25 +44,38 @@ static unsigned getRefSize(const DWARFYAML::Unit &Unit) {
 }
 
 template <typename T> void DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
+  // XXX BINARYEN: Handle multiple linked compile units. Each one has its own
+  // range of values, terminated by a zero. AbbrevStart refers to the start
+  // index for the current unit, and AbbrevEnd to one past the last one
+  // (which is the index of the 0 terminator).
+  // TODO: This code appears to assume that abbreviation codes increment by 1
+  // so that lookups are linear. In LLVM output that is true, but it might not
+  // be in general.
+  size_t AbbrevStart = 0, AbbrevEnd = -1;
   for (auto &Unit : DebugInfo.CompileUnits) {
+    // Skip the 0 terminator.
+    AbbrevEnd = AbbrevStart = AbbrevEnd + 1;
+    while (AbbrevEnd < DebugInfo.AbbrevDecls.size() &&
+           DebugInfo.AbbrevDecls[AbbrevEnd].Code) {
+      AbbrevEnd++;
+    }
     onStartCompileUnit(Unit);
     if (Unit.Entries.empty()) { // XXX BINARYEN
       continue;
     }
     auto FirstAbbrevCode = Unit.Entries[0].AbbrCode;
-
     for (auto &Entry : Unit.Entries) {
       onStartDIE(Unit, Entry);
       if (Entry.AbbrCode == 0u)
         continue;
       // XXX BINARYEN
-      if (Entry.AbbrCode - FirstAbbrevCode >= DebugInfo.AbbrevDecls.size()) {
-        errs() << "warning: invalid abbreviation code " << Entry.AbbrCode <<
-               " (range: " << FirstAbbrevCode << "-" <<
-               (DebugInfo.AbbrevDecls.size() - FirstAbbrevCode) << ")\n";
+      if (Entry.AbbrCode - FirstAbbrevCode + AbbrevStart >= AbbrevEnd) {
+        errs() << "warning: invalid abbreviation code " << Entry.AbbrCode
+               << " (range: " << FirstAbbrevCode << " : " << AbbrevStart
+               << ".." << AbbrevEnd << ")\n";
         continue;
       }
-      auto &Abbrev = DebugInfo.AbbrevDecls[Entry.AbbrCode - FirstAbbrevCode];
+      auto &Abbrev = DebugInfo.AbbrevDecls[Entry.AbbrCode - FirstAbbrevCode + AbbrevStart];
       auto FormVal = Entry.Values.begin();
       auto AbbrForm = Abbrev.Attributes.begin();
       for (;
diff --git a/third_party/llvm-project/dwarf2yaml.cpp b/third_party/llvm-project/dwarf2yaml.cpp
index b43b0e420..52e875637 100644
--- a/third_party/llvm-project/dwarf2yaml.cpp
+++ b/third_party/llvm-project/dwarf2yaml.cpp
@@ -43,6 +43,14 @@ void dumpDebugAbbrev(DWARFContext &DCtx, DWARFYAML::Data &Y) {
         }
         Y.AbbrevDecls.push_back(Abbrv);
       }
+      // XXX BINARYEN: null-terminate the DeclSet. This is needed to separate
+      // DeclSets from each other, and to null-terminate the entire list
+      // (LLVM works with or without this, but other decoders may error, see
+      //  https://bugs.llvm.org/show_bug.cgi?id=44511).
+      DWARFYAML::Abbrev Abbrv;
+      Abbrv.Code = 0;
+      Abbrv.Tag = dwarf::Tag(0);
+      Y.AbbrevDecls.push_back(Abbrv);
     }
   }
 }