1 files changed, 358 insertions, 0 deletions

diff --git a/lib/Transforms/IPO/FunctionResolution.cpp b/lib/Transforms/IPO/FunctionResolution.cpp
new file mode 100644
index 0000000000..8b5019a0af
--- /dev/null
+++ b/lib/Transforms/IPO/FunctionResolution.cpp
@@ -0,0 +1,358 @@
+//===- FunctionResolution.cpp - Resolve declarations to implementations ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Loop over the functions that are in the module and look for functions that
+// have the same name.  More often than not, there will be things like:
+//
+//    declare void %foo(...)
+//    void %foo(int, int) { ... }
+//
+// because of the way things are declared in C.  If this is the case, patch
+// things up.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Module.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Pass.h"
+#include "llvm/Instructions.h"
+#include "llvm/Constants.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Assembly/Writer.h"
+#include "llvm/ADT/Statistic.h"
+#include <algorithm>
+using namespace llvm;
+
+namespace {
+  Statistic<>NumResolved("funcresolve", "Number of varargs functions resolved");
+  Statistic<> NumGlobals("funcresolve", "Number of global variables resolved");
+
+  struct FunctionResolvingPass : public ModulePass {
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addRequired<TargetData>();
+    }
+
+    bool runOnModule(Module &M);
+  };
+  RegisterOpt<FunctionResolvingPass> X("funcresolve", "Resolve Functions");
+}
+
+ModulePass *llvm::createFunctionResolvingPass() {
+  return new FunctionResolvingPass();
+}
+
+static bool ResolveFunctions(Module &M, std::vector<GlobalValue*> &Globals,
+                             Function *Concrete) {
+  bool Changed = false;
+  for (unsigned i = 0; i != Globals.size(); ++i)
+    if (Globals[i] != Concrete) {
+      Function *Old = cast<Function>(Globals[i]);
+      const FunctionType *OldMT = Old->getFunctionType();
+      const FunctionType *ConcreteMT = Concrete->getFunctionType();
+
+      if (OldMT->getNumParams() > ConcreteMT->getNumParams() &&
+          !ConcreteMT->isVarArg())
+        if (!Old->use_empty()) {
+          std::cerr << "WARNING: Linking function '" << Old->getName()
+                    << "' is causing arguments to be dropped.\n";
+          std::cerr << "WARNING: Prototype: ";
+          WriteAsOperand(std::cerr, Old);
+          std::cerr << " resolved to ";
+          WriteAsOperand(std::cerr, Concrete);
+          std::cerr << "\n";
+        }
+
+      // Check to make sure that if there are specified types, that they
+      // match...
+      //
+      unsigned NumArguments = std::min(OldMT->getNumParams(),
+                                       ConcreteMT->getNumParams());
+
+      if (!Old->use_empty() && !Concrete->use_empty())
+        for (unsigned i = 0; i < NumArguments; ++i)
+          if (OldMT->getParamType(i) != ConcreteMT->getParamType(i))
+            if (OldMT->getParamType(i)->getTypeID() !=
+                ConcreteMT->getParamType(i)->getTypeID()) {
+              std::cerr << "WARNING: Function [" << Old->getName()
+                        << "]: Parameter types conflict for: '";
+              WriteTypeSymbolic(std::cerr, OldMT, &M);
+              std::cerr << "' and '";
+              WriteTypeSymbolic(std::cerr, ConcreteMT, &M);
+              std::cerr << "'\n";
+              return Changed;
+            }
+
+      // Attempt to convert all of the uses of the old function to the concrete
+      // form of the function.  If there is a use of the fn that we don't
+      // understand here we punt to avoid making a bad transformation.
+      //
+      // At this point, we know that the return values are the same for our two
+      // functions and that the Old function has no varargs fns specified.  In
+      // otherwords it's just <retty> (...)
+      //
+      if (!Old->use_empty()) {
+        Value *Replacement = Concrete;
+        if (Concrete->getType() != Old->getType())
+          Replacement = ConstantExpr::getCast(Concrete, Old->getType());
+        NumResolved += Old->getNumUses();
+        Old->replaceAllUsesWith(Replacement);
+      }
+
+      // Since there are no uses of Old anymore, remove it from the module.
+      M.getFunctionList().erase(Old);
+    }
+  return Changed;
+}
+
+
+static bool ResolveGlobalVariables(Module &M,
+                                   std::vector<GlobalValue*> &Globals,
+                                   GlobalVariable *Concrete) {
+  bool Changed = false;
+
+  for (unsigned i = 0; i != Globals.size(); ++i)
+    if (Globals[i] != Concrete) {
+      Constant *Cast = ConstantExpr::getCast(Concrete, Globals[i]->getType());
+      Globals[i]->replaceAllUsesWith(Cast);
+
+      // Since there are no uses of Old anymore, remove it from the module.
+      M.getGlobalList().erase(cast<GlobalVariable>(Globals[i]));
+
+      ++NumGlobals;
+      Changed = true;
+    }
+  return Changed;
+}
+
+// Check to see if all of the callers of F ignore the return value.
+static bool CallersAllIgnoreReturnValue(Function &F) {
+  if (F.getReturnType() == Type::VoidTy) return true;
+  for (Value::use_iterator I = F.use_begin(), E = F.use_end(); I != E; ++I) {
+    if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
+      for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
+           I != E; ++I) {
+        CallSite CS = CallSite::get(*I);
+        if (!CS.getInstruction() || !CS.getInstruction()->use_empty())
+          return false;
+      }
+    } else {
+      CallSite CS = CallSite::get(*I);
+      if (!CS.getInstruction() || !CS.getInstruction()->use_empty())
+        return false;
+    }
+  }
+  return true;
+}
+
+static bool ProcessGlobalsWithSameName(Module &M, TargetData &TD,
+                                       std::vector<GlobalValue*> &Globals) {
+  assert(!Globals.empty() && "Globals list shouldn't be empty here!");
+
+  bool isFunction = isa<Function>(Globals[0]);   // Is this group all functions?
+  GlobalValue *Concrete = 0;  // The most concrete implementation to resolve to
+
+  for (unsigned i = 0; i != Globals.size(); ) {
+    if (isa<Function>(Globals[i]) != isFunction) {
+      std::cerr << "WARNING: Found function and global variable with the "
+                << "same name: '" << Globals[i]->getName() << "'.\n";
+      return false;                 // Don't know how to handle this, bail out!
+    }
+
+    if (isFunction) {
+      // For functions, we look to merge functions definitions of "int (...)"
+      // to 'int (int)' or 'int ()' or whatever else is not completely generic.
+      //
+      Function *F = cast<Function>(Globals[i]);
+      if (!F->isExternal()) {
+        if (Concrete && !Concrete->isExternal())
+          return false;   // Found two different functions types.  Can't choose!
+
+        Concrete = Globals[i];
+      } else if (Concrete) {
+        if (Concrete->isExternal()) // If we have multiple external symbols...
+          if (F->getFunctionType()->getNumParams() >
+              cast<Function>(Concrete)->getFunctionType()->getNumParams())
+            Concrete = F;  // We are more concrete than "Concrete"!
+
+      } else {
+        Concrete = F;
+      }
+    } else {
+      GlobalVariable *GV = cast<GlobalVariable>(Globals[i]);
+      if (!GV->isExternal()) {
+        if (Concrete) {
+          std::cerr << "WARNING: Two global variables with external linkage"
+                    << " exist with the same name: '" << GV->getName()
+                    << "'!\n";
+          return false;
+        }
+        Concrete = GV;
+      }
+    }
+    ++i;
+  }
+
+  if (Globals.size() > 1) {         // Found a multiply defined global...
+    // If there are no external declarations, and there is at most one
+    // externally visible instance of the global, then there is nothing to do.
+    //
+    bool HasExternal = false;
+    unsigned NumInstancesWithExternalLinkage = 0;
+
+    for (unsigned i = 0, e = Globals.size(); i != e; ++i) {
+      if (Globals[i]->isExternal())
+        HasExternal = true;
+      else if (!Globals[i]->hasInternalLinkage())
+        NumInstancesWithExternalLinkage++;
+    }
+
+    if (!HasExternal && NumInstancesWithExternalLinkage <= 1)
+      return false;  // Nothing to do?  Must have multiple internal definitions.
+
+    // There are a couple of special cases we don't want to print the warning
+    // for, check them now.
+    bool DontPrintWarning = false;
+    if (Concrete && Globals.size() == 2) {
+      GlobalValue *Other = Globals[Globals[0] == Concrete];
+      // If the non-concrete global is a function which takes (...) arguments,
+      // and the return values match (or was never used), do not warn.
+      if (Function *ConcreteF = dyn_cast<Function>(Concrete))
+        if (Function *OtherF = dyn_cast<Function>(Other))
+          if ((ConcreteF->getReturnType() == OtherF->getReturnType() ||
+               CallersAllIgnoreReturnValue(*OtherF)) &&
+              OtherF->getFunctionType()->isVarArg() &&
+              OtherF->getFunctionType()->getNumParams() == 0)
+            DontPrintWarning = true;
+
+      // Otherwise, if the non-concrete global is a global array variable with a
+      // size of 0, and the concrete global is an array with a real size, don't
+      // warn.  This occurs due to declaring 'extern int A[];'.
+      if (GlobalVariable *ConcreteGV = dyn_cast<GlobalVariable>(Concrete))
+        if (GlobalVariable *OtherGV = dyn_cast<GlobalVariable>(Other)) {
+          const Type *CTy = ConcreteGV->getType();
+          const Type *OTy = OtherGV->getType();
+
+          if (CTy->isSized())
+            if (!OTy->isSized() || !TD.getTypeSize(OTy) ||
+                TD.getTypeSize(OTy) == TD.getTypeSize(CTy))
+              DontPrintWarning = true;
+        }
+    }
+
+    if (0 && !DontPrintWarning) {
+      std::cerr << "WARNING: Found global types that are not compatible:\n";
+      for (unsigned i = 0; i < Globals.size(); ++i) {
+        std::cerr << "\t";
+        WriteTypeSymbolic(std::cerr, Globals[i]->getType(), &M);
+        std::cerr << " %" << Globals[i]->getName() << "\n";
+      }
+    }
+
+    if (!Concrete)
+      Concrete = Globals[0];
+    else if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Concrete)) {
+      // Handle special case hack to change globals if it will make their types
+      // happier in the long run.  The situation we do this is intentionally
+      // extremely limited.
+      if (GV->use_empty() && GV->hasInitializer() &&
+          GV->getInitializer()->isNullValue()) {
+        // Check to see if there is another (external) global with the same size
+        // and a non-empty use-list.  If so, we will make IT be the real
+        // implementation.
+        unsigned TS = TD.getTypeSize(Concrete->getType()->getElementType());
+        for (unsigned i = 0, e = Globals.size(); i != e; ++i)
+          if (Globals[i] != Concrete && !Globals[i]->use_empty() &&
+              isa<GlobalVariable>(Globals[i]) &&
+              TD.getTypeSize(Globals[i]->getType()->getElementType()) == TS) {
+            // At this point we want to replace Concrete with Globals[i].  Make
+            // concrete external, and Globals[i] have an initializer.
+            GlobalVariable *NGV = cast<GlobalVariable>(Globals[i]);
+            const Type *ElTy = NGV->getType()->getElementType();
+            NGV->setInitializer(Constant::getNullValue(ElTy));
+            cast<GlobalVariable>(Concrete)->setInitializer(0);
+            Concrete = NGV;
+            break;
+          }
+      }
+    }
+
+    if (isFunction)
+      return ResolveFunctions(M, Globals, cast<Function>(Concrete));
+    else
+      return ResolveGlobalVariables(M, Globals,
+                                    cast<GlobalVariable>(Concrete));
+  }
+  return false;
+}
+
+bool FunctionResolvingPass::runOnModule(Module &M) {
+  std::map<std::string, std::vector<GlobalValue*> > Globals;
+
+  // Loop over the globals, adding them to the Globals map.  We use a two pass
+  // algorithm here to avoid problems with iterators getting invalidated if we
+  // did a one pass scheme.
+  //
+  bool Changed = false;
+  for (Module::iterator I = M.begin(), E = M.end(); I != E; ) {
+    Function *F = I++;
+    if (F->use_empty() && F->isExternal()) {
+      M.getFunctionList().erase(F);
+      Changed = true;
+    } else if (!F->hasInternalLinkage() && !F->getName().empty() &&
+               !F->getIntrinsicID())
+      Globals[F->getName()].push_back(F);
+  }
+
+  for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ) {
+    GlobalVariable *GV = I++;
+    if (GV->use_empty() && GV->isExternal()) {
+      M.getGlobalList().erase(GV);
+      Changed = true;
+    } else if (!GV->hasInternalLinkage() && !GV->getName().empty())
+      Globals[GV->getName()].push_back(GV);
+  }
+
+  TargetData &TD = getAnalysis<TargetData>();
+
+  // Now we have a list of all functions with a particular name.  If there is
+  // more than one entry in a list, merge the functions together.
+  //
+  for (std::map<std::string, std::vector<GlobalValue*> >::iterator
+         I = Globals.begin(), E = Globals.end(); I != E; ++I)
+    Changed |= ProcessGlobalsWithSameName(M, TD, I->second);
+
+  // Now loop over all of the globals, checking to see if any are trivially
+  // dead.  If so, remove them now.
+
+  for (Module::iterator I = M.begin(), E = M.end(); I != E; )
+    if (I->isExternal() && I->use_empty()) {
+      Function *F = I;
+      ++I;
+      M.getFunctionList().erase(F);
+      ++NumResolved;
+      Changed = true;
+    } else {
+      ++I;
+    }
+
+  for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; )
+    if (I->isExternal() && I->use_empty()) {
+      GlobalVariable *GV = I;
+      ++I;
+      M.getGlobalList().erase(GV);
+      ++NumGlobals;
+      Changed = true;
+    } else {
+      ++I;
+    }
+
+  return Changed;
+}