[llvm] r212850 - [ASan] Introduce a struct representing the layout of metadata entry in llvm.asan.globals.

[Alexey Samsonov]

Author: samsonov
Date: Fri Jul 11 17:36:02 2014
New Revision: 212850

URL: http://llvm.org/viewvc/llvm-project?rev=212850&view=rev
Log:
[ASan] Introduce a struct representing the layout of metadata entry in llvm.asan.globals.

No functionality change.


Modified:
    llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp

Modified: llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp?rev=212850&r1=212849&r2=212850&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp Fri Jul 11 17:36:02 2014
@@ -215,7 +215,15 @@ namespace {
 /// Frontend-provided metadata for global variables.
 class GlobalsMetadata {
  public:
+  struct Entry {
+    Entry() : SourceLoc(nullptr), IsDynInit(false), IsBlacklisted(false) {}
+    GlobalVariable *SourceLoc;
+    bool IsDynInit;
+    bool IsBlacklisted;
+  };
+
   GlobalsMetadata() : inited_(false) {}
+
   void init(Module& M) {
     assert(!inited_);
     inited_ = true;
@@ -223,62 +231,45 @@ class GlobalsMetadata {
     if (!Globals)
       return;
     for (auto MDN : Globals->operands()) {
-      // Format of the metadata node for the global:
-      // {
-      //   global,
-      //   source_location,
-      //   i1 is_dynamically_initialized,
-      //   i1 is_blacklisted
-      // }
+      // Metadata node contains the global and the fields of "Entry".
       assert(MDN->getNumOperands() == 4);
       Value *V = MDN->getOperand(0);
       // The optimizer may optimize away a global entirely.
       if (!V)
         continue;
       GlobalVariable *GV = cast<GlobalVariable>(V);
+      // We can already have an entry for GV if it was merged with another
+      // global.
+      Entry &E = Entries[GV];
       if (Value *Loc = MDN->getOperand(1)) {
         GlobalVariable *GVLoc = cast<GlobalVariable>(Loc);
-        // We may already know the source location for GV, if it was merged
-        // with another global.
-        if (SourceLocation.insert(std::make_pair(GV, GVLoc)).second)
-          addSourceLocationGlobal(GVLoc);
+        E.SourceLoc = GVLoc;
+        addSourceLocationGlobal(GVLoc);
       }
       ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(2));
-      if (IsDynInit->isOne())
-        DynInitGlobals.insert(GV);
+      E.IsDynInit |= IsDynInit->isOne();
       ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(3));
-      if (IsBlacklisted->isOne())
-        BlacklistedGlobals.insert(GV);
+      E.IsBlacklisted |= IsBlacklisted->isOne();
     }
   }
 
-  GlobalVariable *getSourceLocation(GlobalVariable *G) const {
-    auto Pos = SourceLocation.find(G);
-    return (Pos != SourceLocation.end()) ? Pos->second : nullptr;
-  }
-
-  /// Check if the global is dynamically initialized.
-  bool isDynInit(GlobalVariable *G) const {
-    return DynInitGlobals.count(G);
-  }
-
-  /// Check if the global was blacklisted.
-  bool isBlacklisted(GlobalVariable *G) const {
-    return BlacklistedGlobals.count(G);
+  /// Returns metadata entry for a given global.
+  Entry get(GlobalVariable *G) const {
+    auto Pos = Entries.find(G);
+    return (Pos != Entries.end()) ? Pos->second : Entry();
   }
 
-  /// Check if the global was generated to describe source location of another
-  /// global (we don't want to instrument them).
-  bool isSourceLocationGlobal(GlobalVariable *G) const {
-    return LocationGlobals.count(G);
+  /// Check if the global was generated by the instrumentation
+  /// (we don't want to instrument it again in this case).
+  bool isInstrumentationGlobal(GlobalVariable *G) const {
+    return InstrumentationGlobals.count(G);
   }
 
  private:
   bool inited_;
-  DenseMap<GlobalVariable*, GlobalVariable*> SourceLocation;
-  DenseSet<GlobalVariable*> DynInitGlobals;
-  DenseSet<GlobalVariable*> BlacklistedGlobals;
-  DenseSet<GlobalVariable*> LocationGlobals;
+  DenseMap<GlobalVariable*, Entry> Entries;
+  // Globals generated by the frontend instrumentation.
+  DenseSet<GlobalVariable*> InstrumentationGlobals;
 
   void addSourceLocationGlobal(GlobalVariable *SourceLocGV) {
     // Source location global is a struct with layout:
@@ -287,11 +278,11 @@ class GlobalsMetadata {
     //    i32 line_number,
     //    i32 column_number,
     // }
-    LocationGlobals.insert(SourceLocGV);
+    InstrumentationGlobals.insert(SourceLocGV);
     ConstantStruct *Contents =
         cast<ConstantStruct>(SourceLocGV->getInitializer());
     GlobalVariable *FilenameGV = cast<GlobalVariable>(Contents->getOperand(0));
-    LocationGlobals.insert(FilenameGV);
+    InstrumentationGlobals.insert(FilenameGV);
   }
 };
 
@@ -710,7 +701,7 @@ bool AddressSanitizer::GlobalIsLinkerIni
   // If a global variable does not have dynamic initialization we don't
   // have to instrument it.  However, if a global does not have initializer
   // at all, we assume it has dynamic initializer (in other TU).
-  return G->hasInitializer() && !GlobalsMD.isDynInit(G);
+  return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
 }
 
 void
@@ -917,8 +908,8 @@ bool AddressSanitizerModule::ShouldInstr
   Type *Ty = cast<PointerType>(G->getType())->getElementType();
   DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
 
-  if (GlobalsMD.isBlacklisted(G)) return false;
-  if (GlobalsMD.isSourceLocationGlobal(G)) return false;
+  if (GlobalsMD.get(G).IsBlacklisted) return false;
+  if (GlobalsMD.isInstrumentationGlobal(G)) return false;
   if (!Ty->isSized()) return false;
   if (!G->hasInitializer()) return false;
   if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
@@ -1101,8 +1092,7 @@ bool AddressSanitizerModule::InstrumentG
     NewGlobal->takeName(G);
     G->eraseFromParent();
 
-    bool GlobalHasDynamicInitializer = GlobalsMD.isDynInit(G);
-    GlobalVariable *SourceLoc = GlobalsMD.getSourceLocation(G);
+    auto MD = GlobalsMD.get(G);
 
     Initializers[i] = ConstantStruct::get(
         GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
@@ -1110,12 +1100,12 @@ bool AddressSanitizerModule::InstrumentG
         ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
         ConstantExpr::getPointerCast(Name, IntptrTy),
         ConstantExpr::getPointerCast(ModuleName, IntptrTy),
-        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
-        SourceLoc ? ConstantExpr::getPointerCast(SourceLoc, IntptrTy)
-                  : ConstantInt::get(IntptrTy, 0),
+        ConstantInt::get(IntptrTy, MD.IsDynInit),
+        MD.SourceLoc ? ConstantExpr::getPointerCast(MD.SourceLoc, IntptrTy)
+                     : ConstantInt::get(IntptrTy, 0),
         NULL);
 
-    if (ClInitializers && GlobalHasDynamicInitializer)
+    if (ClInitializers && MD.IsDynInit)
       HasDynamicallyInitializedGlobals = true;
 
     DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");