DebugInfo: Split DWARF + gmlt + no-split-dwarf-inlining shouldn't emit anything to the .dwo file

This configuration (due to r349207) was intended not to emit any DWO CU,
but a degenerate CU was still being emitted - containing a header and a
DW_TAG_compile_unit with no attributes.

Under that situation, emit nothing to the .dwo file. (since this is a
dynamic property of the input the .dwo file is still emitted, just with
nothing in it (so a valid, but empty, ELF file) - if some other CU
didn't satisfy this criteria, its DWO CU would still go there, etc)

llvm-svn: 353771

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 56a99b5365b..e3c9095d134 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -43,6 +43,11 @@ void DwarfFile::emitUnit(DwarfUnit *TheU, bool UseOffsets) {
   if (!S)
     return;
 
+  // Skip CUs that ended up not being needed (split CUs that were abandoned
+  // because they added no information beyond the non-split CU)
+  if (llvm::empty(TheU->getUnitDie().values()))
+    return;
+
   Asm->OutStreamer->SwitchSection(S);
   TheU->emitHeader(UseOffsets);
   Asm->emitDwarfDIE(TheU->getUnitDie());
@@ -62,6 +67,11 @@ void DwarfFile::computeSizeAndOffsets() {
     if (TheU->getCUNode()->isDebugDirectivesOnly())
       continue;
 
+    // Skip CUs that ended up not being needed (split CUs that were abandoned
+    // because they added no information beyond the non-split CU)
+    if (llvm::empty(TheU->getUnitDie().values()))
+      return;
+
     TheU->setDebugSectionOffset(SecOffset);
     SecOffset += computeSizeAndOffsetsForUnit(TheU.get());
   }