[ASan] Collect unmangled names of global variables in Clang to print them in error reports.

Currently ASan instrumentation pass creates a string with global name
for each instrumented global (to include global names in the error report). Global
name is already mangled at this point, and we may not be able to demangle it
at runtime (e.g. there is no __cxa_demangle on Android).

Instead, create a string with fully qualified global name in Clang, and pass it
to ASan instrumentation pass in llvm.asan.globals metadata. If there is no metadata
for some global, ASan will use the original algorithm.

This fixes https://code.google.com/p/address-sanitizer/issues/detail?id=264.

llvm-svn: 212872

1 files changed, 20 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 17cfd92ff27..e42839c9c6b 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -216,8 +216,11 @@ namespace {
 class GlobalsMetadata {
  public:
   struct Entry {
-    Entry() : SourceLoc(nullptr), IsDynInit(false), IsBlacklisted(false) {}
+    Entry()
+        : SourceLoc(nullptr), Name(nullptr), IsDynInit(false),
+          IsBlacklisted(false) {}
     GlobalVariable *SourceLoc;
+    GlobalVariable *Name;
     bool IsDynInit;
     bool IsBlacklisted;
   };
@@ -232,7 +235,7 @@ class GlobalsMetadata {
       return;
     for (auto MDN : Globals->operands()) {
       // Metadata node contains the global and the fields of "Entry".
-      assert(MDN->getNumOperands() == 4);
+      assert(MDN->getNumOperands() == 5);
       Value *V = MDN->getOperand(0);
       // The optimizer may optimize away a global entirely.
       if (!V)
@@ -246,9 +249,14 @@ class GlobalsMetadata {
         E.SourceLoc = GVLoc;
         addSourceLocationGlobal(GVLoc);
       }
-      ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(2));
+      if (Value *Name = MDN->getOperand(2)) {
+        GlobalVariable *GVName = cast<GlobalVariable>(Name);
+        E.Name = GVName;
+        InstrumentationGlobals.insert(GVName);
+      }
+      ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
       E.IsDynInit |= IsDynInit->isOne();
-      ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(3));
+      ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
       E.IsBlacklisted |= IsBlacklisted->isOne();
     }
   }
@@ -1049,6 +1057,14 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
   for (size_t i = 0; i < n; i++) {
     static const uint64_t kMaxGlobalRedzone = 1 << 18;
     GlobalVariable *G = GlobalsToChange[i];
+
+    auto MD = GlobalsMD.get(G);
+    // Create string holding the global name unless it was provided by
+    // the metadata.
+    GlobalVariable *Name =
+        MD.Name ? MD.Name : createPrivateGlobalForString(M, G->getName(),
+                                                         /*AllowMerging*/ true);
+
     PointerType *PtrTy = cast<PointerType>(G->getType());
     Type *Ty = PtrTy->getElementType();
     uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
@@ -1070,9 +1086,6 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
         NewTy, G->getInitializer(),
         Constant::getNullValue(RightRedZoneTy), NULL);
 
-    GlobalVariable *Name =
-        createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
-
     // Create a new global variable with enough space for a redzone.
     GlobalValue::LinkageTypes Linkage = G->getLinkage();
     if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
@@ -1092,8 +1105,6 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
     NewGlobal->takeName(G);
     G->eraseFromParent();
 
-    auto MD = GlobalsMD.get(G);
-
     Initializers[i] = ConstantStruct::get(
         GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
         ConstantInt::get(IntptrTy, SizeInBytes),