[DwarfDebug] Skip entries to big for 16 bit size field in Dwarf < 5.

Nothing prevents entries from being bigger than the 16 bit size field in
Dwarf < 5. For entries that are too big, just emit an empty entry
instead of crashing.

This fixes PR41038.

Reviewers: probinson, aprantl, davide

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D59518

llvm-svn: 356514

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 3e60f15..0e0a5b2 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2037,8 +2037,14 @@ void DwarfDebug::emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry,
   Asm->OutStreamer->AddComment("Loc expr size");
   if (getDwarfVersion() >= 5)
     Asm->EmitULEB128(DebugLocs.getBytes(Entry).size());
-  else
+  else if (DebugLocs.getBytes(Entry).size() <= std::numeric_limits<uint16_t>::max())
     Asm->emitInt16(DebugLocs.getBytes(Entry).size());
+  else {
+    // The entry is too big to fit into 16 bit, drop it as there is nothing we
+    // can do.
+    Asm->emitInt16(0);
+    return;
+  }
   // Emit the entry.
   APByteStreamer Streamer(*Asm);
   emitDebugLocEntry(Streamer, Entry, CU);