1 files changed, 31 insertions, 2 deletions

diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 77879021f9af..d815863e929d 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -1323,6 +1323,10 @@ static CSFC_Result CollectStatementsForCase(const Stmt *S,
     // Handle this as two cases: we might be looking for the SwitchCase (if so
     // the skipped statements must be skippable) or we might already have it.
     CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
+    bool StartedInLiveCode = FoundCase;
+    unsigned StartSize = ResultStmts.size();
+
+    // If we've not found the case yet, scan through looking for it.
     if (Case) {
       // Keep track of whether we see a skipped declaration.  The code could be
       // using the declaration even if it is skipped, so we can't optimize out
@@ -1332,7 +1336,7 @@ static CSFC_Result CollectStatementsForCase(const Stmt *S,
       // If we're looking for the case, just see if we can skip each of the
       // substatements.
       for (; Case && I != E; ++I) {
-        HadSkippedDecl |= isa<DeclStmt>(*I);
+        HadSkippedDecl |= CodeGenFunction::mightAddDeclToScope(*I);
 
         switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
         case CSFC_Failure: return CSFC_Failure;
@@ -1368,11 +1372,19 @@ static CSFC_Result CollectStatementsForCase(const Stmt *S,
           break;
         }
       }
+
+      if (!FoundCase)
+        return CSFC_Success;
+
+      assert(!HadSkippedDecl && "fallthrough after skipping decl");
     }
 
     // If we have statements in our range, then we know that the statements are
     // live and need to be added to the set of statements we're tracking.
+    bool AnyDecls = false;
     for (; I != E; ++I) {
+      AnyDecls |= CodeGenFunction::mightAddDeclToScope(*I);
+
       switch (CollectStatementsForCase(*I, nullptr, FoundCase, ResultStmts)) {
       case CSFC_Failure: return CSFC_Failure;
       case CSFC_FallThrough:
@@ -1390,7 +1402,24 @@ static CSFC_Result CollectStatementsForCase(const Stmt *S,
       }
     }
 
-    return Case ? CSFC_Success : CSFC_FallThrough;
+    // If we're about to fall out of a scope without hitting a 'break;', we
+    // can't perform the optimization if there were any decls in that scope
+    // (we'd lose their end-of-lifetime).
+    if (AnyDecls) {
+      // If the entire compound statement was live, there's one more thing we
+      // can try before giving up: emit the whole thing as a single statement.
+      // We can do that unless the statement contains a 'break;'.
+      // FIXME: Such a break must be at the end of a construct within this one.
+      // We could emit this by just ignoring the BreakStmts entirely.
+      if (StartedInLiveCode && !CodeGenFunction::containsBreak(S)) {
+        ResultStmts.resize(StartSize);
+        ResultStmts.push_back(S);
+      } else {
+        return CSFC_Failure;
+      }
+    }
+
+    return CSFC_FallThrough;
   }
 
   // Okay, this is some other statement that we don't handle explicitly, like a