[opt] Strip coverage if debug info is not present.

If -coverage is passed, but -g is not, clang populates the PassManager
pipeline with StripSymbols(debugOnly = true).
The stripSymbol pass therefore scans the list of named metadata,
drops !llvm.dbg.cu, but leaves !llvm.gcov and !0 (the compileUnit MD)
around. The verifier runs, and finds out that there's a CU not listed
in !llvm.dbg.cu (as it was previously dropped) -> crash.
When we strip debug info, so, check if there's coverage data,
and strip it as well, in order to avoid pending metadata left around.

Differential Revision:  https://reviews.llvm.org/D25689

llvm-svn: 284418

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index 80f97b3e049..be00387682f 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -272,7 +272,11 @@ bool llvm::StripDebugInfo(Module &M) {
          NME = M.named_metadata_end(); NMI != NME;) {
     NamedMDNode *NMD = &*NMI;
     ++NMI;
-    if (NMD->getName().startswith("llvm.dbg.")) {
+
+    // We're stripping debug info, and without them, coverage information
+    // doesn't quite make sense.
+    if (NMD->getName().startswith("llvm.dbg.") ||
+        NMD->getName() == "llvm.gcov") {
       NMD->eraseFromParent();
       Changed = true;
     }