1 files changed, 357 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/IPO/StripSymbols.cpp b/contrib/llvm/lib/Transforms/IPO/StripSymbols.cpp
new file mode 100644
index 0000000..60c9573
--- /dev/null
+++ b/contrib/llvm/lib/Transforms/IPO/StripSymbols.cpp
@@ -0,0 +1,357 @@
+//===- StripSymbols.cpp - Strip symbols and debug info from a module ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The StripSymbols transformation implements code stripping. Specifically, it
+// can delete:
+//
+//   * names for virtual registers
+//   * symbols for internal globals and functions
+//   * debug information
+//
+// Note that this transformation makes code much less readable, so it should
+// only be used in situations where the 'strip' utility would be used, such as
+// reducing code size or making it harder to reverse engineer code.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/TypeFinder.h"
+#include "llvm/IR/ValueSymbolTable.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Utils/Local.h"
+using namespace llvm;
+
+namespace {
+  class StripSymbols : public ModulePass {
+    bool OnlyDebugInfo;
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    explicit StripSymbols(bool ODI = false)
+      : ModulePass(ID), OnlyDebugInfo(ODI) {
+        initializeStripSymbolsPass(*PassRegistry::getPassRegistry());
+      }
+
+    bool runOnModule(Module &M) override;
+
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.setPreservesAll();
+    }
+  };
+
+  class StripNonDebugSymbols : public ModulePass {
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    explicit StripNonDebugSymbols()
+      : ModulePass(ID) {
+        initializeStripNonDebugSymbolsPass(*PassRegistry::getPassRegistry());
+      }
+
+    bool runOnModule(Module &M) override;
+
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.setPreservesAll();
+    }
+  };
+
+  class StripDebugDeclare : public ModulePass {
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    explicit StripDebugDeclare()
+      : ModulePass(ID) {
+        initializeStripDebugDeclarePass(*PassRegistry::getPassRegistry());
+      }
+
+    bool runOnModule(Module &M) override;
+
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.setPreservesAll();
+    }
+  };
+
+  class StripDeadDebugInfo : public ModulePass {
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    explicit StripDeadDebugInfo()
+      : ModulePass(ID) {
+        initializeStripDeadDebugInfoPass(*PassRegistry::getPassRegistry());
+      }
+
+    bool runOnModule(Module &M) override;
+
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.setPreservesAll();
+    }
+  };
+}
+
+char StripSymbols::ID = 0;
+INITIALIZE_PASS(StripSymbols, "strip",
+                "Strip all symbols from a module", false, false)
+
+ModulePass *llvm::createStripSymbolsPass(bool OnlyDebugInfo) {
+  return new StripSymbols(OnlyDebugInfo);
+}
+
+char StripNonDebugSymbols::ID = 0;
+INITIALIZE_PASS(StripNonDebugSymbols, "strip-nondebug",
+                "Strip all symbols, except dbg symbols, from a module",
+                false, false)
+
+ModulePass *llvm::createStripNonDebugSymbolsPass() {
+  return new StripNonDebugSymbols();
+}
+
+char StripDebugDeclare::ID = 0;
+INITIALIZE_PASS(StripDebugDeclare, "strip-debug-declare",
+                "Strip all llvm.dbg.declare intrinsics", false, false)
+
+ModulePass *llvm::createStripDebugDeclarePass() {
+  return new StripDebugDeclare();
+}
+
+char StripDeadDebugInfo::ID = 0;
+INITIALIZE_PASS(StripDeadDebugInfo, "strip-dead-debug-info",
+                "Strip debug info for unused symbols", false, false)
+
+ModulePass *llvm::createStripDeadDebugInfoPass() {
+  return new StripDeadDebugInfo();
+}
+
+/// OnlyUsedBy - Return true if V is only used by Usr.
+static bool OnlyUsedBy(Value *V, Value *Usr) {
+  for (User *U : V->users())
+    if (U != Usr)
+      return false;
+
+  return true;
+}
+
+static void RemoveDeadConstant(Constant *C) {
+  assert(C->use_empty() && "Constant is not dead!");
+  SmallPtrSet<Constant*, 4> Operands;
+  for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
+    if (OnlyUsedBy(C->getOperand(i), C))
+      Operands.insert(cast<Constant>(C->getOperand(i)));
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
+    if (!GV->hasLocalLinkage()) return;   // Don't delete non-static globals.
+    GV->eraseFromParent();
+  }
+  else if (!isa<Function>(C))
+    if (isa<CompositeType>(C->getType()))
+      C->destroyConstant();
+
+  // If the constant referenced anything, see if we can delete it as well.
+  for (Constant *O : Operands)
+    RemoveDeadConstant(O);
+}
+
+// Strip the symbol table of its names.
+//
+static void StripSymtab(ValueSymbolTable &ST, bool PreserveDbgInfo) {
+  for (ValueSymbolTable::iterator VI = ST.begin(), VE = ST.end(); VI != VE; ) {
+    Value *V = VI->getValue();
+    ++VI;
+    if (!isa<GlobalValue>(V) || cast<GlobalValue>(V)->hasLocalLinkage()) {
+      if (!PreserveDbgInfo || !V->getName().startswith("llvm.dbg"))
+        // Set name to "", removing from symbol table!
+        V->setName("");
+    }
+  }
+}
+
+// Strip any named types of their names.
+static void StripTypeNames(Module &M, bool PreserveDbgInfo) {
+  TypeFinder StructTypes;
+  StructTypes.run(M, false);
+
+  for (unsigned i = 0, e = StructTypes.size(); i != e; ++i) {
+    StructType *STy = StructTypes[i];
+    if (STy->isLiteral() || STy->getName().empty()) continue;
+
+    if (PreserveDbgInfo && STy->getName().startswith("llvm.dbg"))
+      continue;
+
+    STy->setName("");
+  }
+}
+
+/// Find values that are marked as llvm.used.
+static void findUsedValues(GlobalVariable *LLVMUsed,
+                           SmallPtrSetImpl<const GlobalValue*> &UsedValues) {
+  if (!LLVMUsed) return;
+  UsedValues.insert(LLVMUsed);
+
+  ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
+
+  for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
+    if (GlobalValue *GV =
+          dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
+      UsedValues.insert(GV);
+}
+
+/// StripSymbolNames - Strip symbol names.
+static bool StripSymbolNames(Module &M, bool PreserveDbgInfo) {
+
+  SmallPtrSet<const GlobalValue*, 8> llvmUsedValues;
+  findUsedValues(M.getGlobalVariable("llvm.used"), llvmUsedValues);
+  findUsedValues(M.getGlobalVariable("llvm.compiler.used"), llvmUsedValues);
+
+  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
+       I != E; ++I) {
+    if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
+      if (!PreserveDbgInfo || !I->getName().startswith("llvm.dbg"))
+        I->setName("");     // Internal symbols can't participate in linkage
+  }
+
+  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
+    if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
+      if (!PreserveDbgInfo || !I->getName().startswith("llvm.dbg"))
+        I->setName("");     // Internal symbols can't participate in linkage
+    StripSymtab(I->getValueSymbolTable(), PreserveDbgInfo);
+  }
+
+  // Remove all names from types.
+  StripTypeNames(M, PreserveDbgInfo);
+
+  return true;
+}
+
+bool StripSymbols::runOnModule(Module &M) {
+  bool Changed = false;
+  Changed |= StripDebugInfo(M);
+  if (!OnlyDebugInfo)
+    Changed |= StripSymbolNames(M, false);
+  return Changed;
+}
+
+bool StripNonDebugSymbols::runOnModule(Module &M) {
+  return StripSymbolNames(M, true);
+}
+
+bool StripDebugDeclare::runOnModule(Module &M) {
+
+  Function *Declare = M.getFunction("llvm.dbg.declare");
+  std::vector<Constant*> DeadConstants;
+
+  if (Declare) {
+    while (!Declare->use_empty()) {
+      CallInst *CI = cast<CallInst>(Declare->user_back());
+      Value *Arg1 = CI->getArgOperand(0);
+      Value *Arg2 = CI->getArgOperand(1);
+      assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
+      CI->eraseFromParent();
+      if (Arg1->use_empty()) {
+        if (Constant *C = dyn_cast<Constant>(Arg1))
+          DeadConstants.push_back(C);
+        else
+          RecursivelyDeleteTriviallyDeadInstructions(Arg1);
+      }
+      if (Arg2->use_empty())
+        if (Constant *C = dyn_cast<Constant>(Arg2))
+          DeadConstants.push_back(C);
+    }
+    Declare->eraseFromParent();
+  }
+
+  while (!DeadConstants.empty()) {
+    Constant *C = DeadConstants.back();
+    DeadConstants.pop_back();
+    if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
+      if (GV->hasLocalLinkage())
+        RemoveDeadConstant(GV);
+    } else
+      RemoveDeadConstant(C);
+  }
+
+  return true;
+}
+
+/// Remove any debug info for global variables/functions in the given module for
+/// which said global variable/function no longer exists (i.e. is null).
+///
+/// Debugging information is encoded in llvm IR using metadata. This is designed
+/// such a way that debug info for symbols preserved even if symbols are
+/// optimized away by the optimizer. This special pass removes debug info for
+/// such symbols.
+bool StripDeadDebugInfo::runOnModule(Module &M) {
+  bool Changed = false;
+
+  LLVMContext &C = M.getContext();
+
+  // Find all debug info in F. This is actually overkill in terms of what we
+  // want to do, but we want to try and be as resilient as possible in the face
+  // of potential debug info changes by using the formal interfaces given to us
+  // as much as possible.
+  DebugInfoFinder F;
+  F.processModule(M);
+
+  // For each compile unit, find the live set of global variables/functions and
+  // replace the current list of potentially dead global variables/functions
+  // with the live list.
+  SmallVector<Metadata *, 64> LiveGlobalVariables;
+  SmallVector<Metadata *, 64> LiveSubprograms;
+  DenseSet<const MDNode *> VisitedSet;
+
+  for (DICompileUnit *DIC : F.compile_units()) {
+    // Create our live subprogram list.
+    bool SubprogramChange = false;
+    for (DISubprogram *DISP : DIC->getSubprograms()) {
+      // Make sure we visit each subprogram only once.
+      if (!VisitedSet.insert(DISP).second)
+        continue;
+
+      // If the function referenced by DISP is not null, the function is live.
+      if (DISP->getFunction())
+        LiveSubprograms.push_back(DISP);
+      else
+        SubprogramChange = true;
+    }
+
+    // Create our live global variable list.
+    bool GlobalVariableChange = false;
+    for (DIGlobalVariable *DIG : DIC->getGlobalVariables()) {
+      // Make sure we only visit each global variable only once.
+      if (!VisitedSet.insert(DIG).second)
+        continue;
+
+      // If the global variable referenced by DIG is not null, the global
+      // variable is live.
+      if (DIG->getVariable())
+        LiveGlobalVariables.push_back(DIG);
+      else
+        GlobalVariableChange = true;
+    }
+
+    // If we found dead subprograms or global variables, replace the current
+    // subprogram list/global variable list with our new live subprogram/global
+    // variable list.
+    if (SubprogramChange) {
+      DIC->replaceSubprograms(MDTuple::get(C, LiveSubprograms));
+      Changed = true;
+    }
+
+    if (GlobalVariableChange) {
+      DIC->replaceGlobalVariables(MDTuple::get(C, LiveGlobalVariables));
+      Changed = true;
+    }
+
+    // Reset lists for the next iteration.
+    LiveSubprograms.clear();
+    LiveGlobalVariables.clear();
+  }
+
+  return Changed;
+}