[Dwarf] early exit to avoid creating dangling DIEs

We used to create children DIEs for a scope, then check whether ScopeDIE is
null. If ScopeDIE is null, the children DIEs will be dangling. Other DIEs can
link to those dangling DIEs, which are not emitted at all, causing dwarf error.

The current testing case is 4k lines, from MultiSource/BenchMark/McCat/09-vor.

rdar://problem/13071959


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174084 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index f3c7a2a..13ad353 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -540,6 +540,12 @@ DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
   if (!Scope || !Scope->getScopeNode())
     return NULL;
 
+  DIScope DS(Scope->getScopeNode());
+  // Early return to avoid creating dangling variable|scope DIEs.
+  if (!Scope->getInlinedAt() && DS.isSubprogram() && Scope->isAbstractScope() &&
+      !TheCU->getDIE(DS))
+    return NULL;
+
   SmallVector<DIE *, 8> Children;
   DIE *ObjectPointer = NULL;
 
@@ -565,7 +571,6 @@ DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
   for (unsigned j = 0, M = Scopes.size(); j < M; ++j)
     if (DIE *Nested = constructScopeDIE(TheCU, Scopes[j]))
       Children.push_back(Nested);
-  DIScope DS(Scope->getScopeNode());
   DIE *ScopeDIE = NULL;
   if (Scope->getInlinedAt())
     ScopeDIE = constructInlinedScopeDIE(TheCU, Scope);