[codeview] Truncate records to maximum record size near 64KB

If we don't truncate, LLVM asserts when the label difference doesn't fit
in a 16 bit field. This patch truncates two kinds of data: trailing null
terminated names in symbol records, and inline line tables. The inline
line table test that I have is too large (many MB), so I'm not checking
it in.

Hopefully fixes PR28264.

llvm-svn: 283403

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCCodeView.cpp b/llvm/lib/MC/MCCodeView.cpp
index ec5dc20a13e..ac1acc08b0c 100644
--- a/llvm/lib/MC/MCCodeView.cpp
+++ b/llvm/lib/MC/MCCodeView.cpp
@@ -358,6 +358,13 @@ void CodeViewContext::encodeInlineLineTable(MCAsmLayout &Layout,
   SmallVectorImpl<char> &Buffer = Frag.getContents();
   Buffer.clear(); // Clear old contents if we went through relaxation.
   for (const MCCVLineEntry &Loc : Locs) {
+    // Exit early if our line table would produce an oversized InlineSiteSym
+    // record. Account for the ChangeCodeLength annotation emitted after the
+    // loop ends.
+    size_t MaxBufferSize = MaxRecordLength - sizeof(InlineSiteSym::Hdr) - 8;
+    if (Buffer.size() >= MaxBufferSize)
+      break;
+
     if (Loc.getFunctionId() == Frag.SiteFuncId) {
       CurSourceLoc.File = Loc.getFileNum();
       CurSourceLoc.Line = Loc.getLine();