2 files changed, 29 insertions, 18 deletions

diff --git a/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp b/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp
index 88fbb233097..f775bdd8202 100644
--- a/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp
+++ b/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp
@@ -92,9 +92,15 @@ void TypeRecordBuilder::writeEncodedUnsignedInteger(uint64_t Value) {
 }
 
 void TypeRecordBuilder::writeNullTerminatedString(StringRef Value) {
-  // Microsoft's linker seems to have trouble with symbol names longer than
-  // 0xffd8 bytes.
-  Value = Value.substr(0, 0xffd8);
+  // Usually the null terminated string comes last, so truncate it to avoid a
+  // record larger than MaxNameLength. Don't do this if this is a list record.
+  // Those have special handling to split the record.
+  unsigned MaxNameLength = MaxRecordLength;
+  if (Kind != TypeRecordKind::FieldList &&
+      Kind != TypeRecordKind::MethodOverloadList)
+    MaxNameLength = maxBytesRemaining();
+  assert(MaxNameLength > 0 && "need room for null terminator");
+  Value = Value.take_front(MaxNameLength - 1);
   Stream.write(Value.data(), Value.size());
   writeUInt8(0);
 }
diff --git a/llvm/lib/DebugInfo/CodeView/TypeTableBuilder.cpp b/llvm/lib/DebugInfo/CodeView/TypeTableBuilder.cpp
index 03f8b1d218b..fcf27962102 100644
--- a/llvm/lib/DebugInfo/CodeView/TypeTableBuilder.cpp
+++ b/llvm/lib/DebugInfo/CodeView/TypeTableBuilder.cpp
@@ -89,6 +89,19 @@ TypeIndex TypeTableBuilder::writeKnownType(const PointerRecord &Record) {
   return writeRecord(Builder);
 }
 
+static void writeNameAndUniqueName(TypeRecordBuilder &Builder, ClassOptions CO,
+                                   StringRef Name, StringRef UniqueName) {
+  // Truncate the names to half the remaining record length.
+  unsigned MaxNameLength = Builder.maxBytesRemaining() / 2;
+  Name = Name.take_front(MaxNameLength - 1);
+  UniqueName = UniqueName.take_front(MaxNameLength - 1);
+
+  Builder.writeNullTerminatedString(Name);
+  if ((CO & ClassOptions::HasUniqueName) != ClassOptions::None) {
+    Builder.writeNullTerminatedString(UniqueName);
+  }
+}
+
 TypeIndex TypeTableBuilder::writeKnownType(const ArrayRecord &Record) {
   TypeRecordBuilder Builder(Record.getKind());
 
@@ -118,11 +131,8 @@ TypeIndex TypeTableBuilder::writeKnownType(const ClassRecord &Record) {
   Builder.writeTypeIndex(Record.getDerivationList());
   Builder.writeTypeIndex(Record.getVTableShape());
   Builder.writeEncodedUnsignedInteger(Record.getSize());
-  Builder.writeNullTerminatedString(Record.getName());
-  if ((Record.getOptions() & ClassOptions::HasUniqueName) !=
-      ClassOptions::None) {
-    Builder.writeNullTerminatedString(Record.getUniqueName());
-  }
+  writeNameAndUniqueName(Builder, Record.getOptions(), Record.getName(),
+                         Record.getUniqueName());
 
   return writeRecord(Builder);
 }
@@ -136,11 +146,8 @@ TypeIndex TypeTableBuilder::writeKnownType(const UnionRecord &Record) {
   Builder.writeUInt16(Flags);
   Builder.writeTypeIndex(Record.getFieldList());
   Builder.writeEncodedUnsignedInteger(Record.getSize());
-  Builder.writeNullTerminatedString(Record.getName());
-  if ((Record.getOptions() & ClassOptions::HasUniqueName) !=
-      ClassOptions::None) {
-    Builder.writeNullTerminatedString(Record.getUniqueName());
-  }
+  writeNameAndUniqueName(Builder, Record.getOptions(), Record.getName(),
+                         Record.getUniqueName());
   return writeRecord(Builder);
 }
 
@@ -151,11 +158,8 @@ TypeIndex TypeTableBuilder::writeKnownType(const EnumRecord &Record) {
   Builder.writeUInt16(static_cast<uint16_t>(Record.getOptions()));
   Builder.writeTypeIndex(Record.getUnderlyingType());
   Builder.writeTypeIndex(Record.getFieldList());
-  Builder.writeNullTerminatedString(Record.getName());
-  if ((Record.getOptions() & ClassOptions::HasUniqueName) !=
-      ClassOptions::None) {
-    Builder.writeNullTerminatedString(Record.getUniqueName());
-  }
+  writeNameAndUniqueName(Builder, Record.getOptions(), Record.getName(),
+                         Record.getUniqueName());
 
   return writeRecord(Builder);
 }
@@ -198,6 +202,7 @@ TypeIndex TypeTableBuilder::writeKnownType(const VFTableRecord &Record) {
   for (StringRef MethodName : Record.getMethodNames())
     NamesLen += MethodName.size() + 1;
 
+  // FIXME: Avoid creating a record longer than MaxRecordLength.
   Builder.writeUInt32(NamesLen);
   Builder.writeNullTerminatedString(Record.getName());
   for (StringRef MethodName : Record.getMethodNames())