[codeview] Delete FunctionInfo copy ctor and move out of DenseMap

We were unnecessarily copying a bunch of these FunctionInfo objects
around when rehashing the DenseMap.

Furthermore, r327620 introduced pointers referring to objects owned by
FunctionInfo, and the default copy ctor did the wrong thing in this
case, leading to use-after-free when the DenseMap gets rehashed.

I will rebase r327620 on this next and recommit it.

llvm-svn: 327665

2 files changed, 11 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 59b6c99f996..1ffc589d7f9 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -470,7 +470,7 @@ void CodeViewDebug::endModule() {
   // Emit per-function debug information.
   for (auto &P : FnDebugInfo)
     if (!P.first->isDeclarationForLinker())
-      emitDebugInfoForFunction(P.first, P.second);
+      emitDebugInfoForFunction(P.first, *P.second);
 
   // Emit global variable debug information.
   setCurrentSubprogram(nullptr);
@@ -1162,8 +1162,9 @@ void CodeViewDebug::collectVariableInfo(const DISubprogram *SP) {
 
 void CodeViewDebug::beginFunctionImpl(const MachineFunction *MF) {
   const Function &GV = MF->getFunction();
-  assert(FnDebugInfo.count(&GV) == false);
-  CurFn = &FnDebugInfo[&GV];
+  auto Insertion = FnDebugInfo.insert({&GV, llvm::make_unique<FunctionInfo>()});
+  assert(!Insertion.second && "emitting function twice");
+  CurFn = Insertion.first->second.get();
   CurFn->FuncId = NextFuncId++;
   CurFn->Begin = Asm->getFunctionBegin();
 
@@ -2365,7 +2366,7 @@ void CodeViewDebug::emitLocalVariable(const LocalVariable &Var) {
 void CodeViewDebug::endFunctionImpl(const MachineFunction *MF) {
   const Function &GV = MF->getFunction();
   assert(FnDebugInfo.count(&GV));
-  assert(CurFn == &FnDebugInfo[&GV]);
+  assert(CurFn == FnDebugInfo[&GV].get());
 
   collectVariableInfo(GV.getSubprogram());
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index fdc8dd4a1e8..0833d217555 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -110,6 +110,11 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
   // For each function, store a vector of labels to its instructions, as well as
   // to the end of the function.
   struct FunctionInfo {
+    FunctionInfo() = default;
+
+    // Uncopyable.
+    FunctionInfo(const FunctionInfo &FI) = delete;
+
     /// Map from inlined call site to inlined instructions and child inlined
     /// call sites. Listed in program order.
     std::unordered_map<const DILocation *, InlineSite> InlineSites;
@@ -159,7 +164,7 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
 
   /// Remember some debug info about each function. Keep it in a stable order to
   /// emit at the end of the TU.
-  MapVector<const Function *, FunctionInfo> FnDebugInfo;
+  MapVector<const Function *, std::unique_ptr<FunctionInfo>> FnDebugInfo;
 
   /// Map from full file path to .cv_file id. Full paths are built from DIFiles
   /// and are stored in FileToFilepathMap;