Split the FunctionResolution pass out of CleanGCCOutput.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2742 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 223 insertions, 0 deletions

diff --git a/lib/Transforms/IPO/FunctionResolution.cpp b/lib/Transforms/IPO/FunctionResolution.cpp
new file mode 100644
index 0000000000..63ea3b1cd3
--- /dev/null
+++ b/lib/Transforms/IPO/FunctionResolution.cpp
@@ -0,0 +1,223 @@
+//===- FunctionResolution.cpp - Resolve declarations to implementations ---===//
+//
+// 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/CleanupGCCOutput.h"
+#include "llvm/Module.h"
+#include "llvm/Function.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/SymbolTable.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Pass.h"
+#include "llvm/iOther.h"
+#include "Support/StatisticReporter.h"
+#include <iostream>
+#include <algorithm>
+
+using std::vector;
+using std::string;
+using std::cerr;
+
+namespace {
+  Statistic<>NumResolved("funcresolve\t- Number of varargs functions resolved");
+
+  struct FunctionResolvingPass : public Pass {
+    const char *getPassName() const { return "Resolve Functions"; }
+
+    bool run(Module *M);
+  };
+}
+
+Pass *createFunctionResolvingPass() {
+  return new FunctionResolvingPass();
+}
+
+// ConvertCallTo - Convert a call to a varargs function with no arg types
+// specified to a concrete nonvarargs function.
+//
+static void ConvertCallTo(CallInst *CI, Function *Dest) {
+  const FunctionType::ParamTypes &ParamTys =
+    Dest->getFunctionType()->getParamTypes();
+  BasicBlock *BB = CI->getParent();
+
+  // Get an iterator to where we want to insert cast instructions if the
+  // argument types don't agree.
+  //
+  BasicBlock::iterator BBI = find(BB->begin(), BB->end(), CI);
+  assert(BBI != BB->end() && "CallInst not in parent block?");
+
+  assert(CI->getNumOperands()-1 == ParamTys.size()&&
+         "Function calls resolved funny somehow, incompatible number of args");
+
+  vector<Value*> Params;
+
+  // Convert all of the call arguments over... inserting cast instructions if
+  // the types are not compatible.
+  for (unsigned i = 1; i < CI->getNumOperands(); ++i) {
+    Value *V = CI->getOperand(i);
+
+    if (V->getType() != ParamTys[i-1]) { // Must insert a cast...
+      Instruction *Cast = new CastInst(V, ParamTys[i-1]);
+      BBI = BB->getInstList().insert(BBI, Cast)+1;
+      V = Cast;
+    }
+
+    Params.push_back(V);
+  }
+
+  // Replace the old call instruction with a new call instruction that calls
+  // the real function.
+  //
+  ReplaceInstWithInst(BB->getInstList(), BBI, new CallInst(Dest, Params));
+}
+
+
+bool FunctionResolvingPass::run(Module *M) {
+  SymbolTable *ST = M->getSymbolTable();
+  if (!ST) return false;
+
+  std::map<string, vector<Function*> > Functions;
+
+  // Loop over the entries in the symbol table. If an entry is a func pointer,
+  // then add it to the Functions map.  We do a two pass algorithm here to avoid
+  // problems with iterators getting invalidated if we did a one pass scheme.
+  //
+  for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
+    if (const PointerType *PT = dyn_cast<PointerType>(I->first))
+      if (isa<FunctionType>(PT->getElementType())) {
+        SymbolTable::VarMap &Plane = I->second;
+        for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
+             PI != PE; ++PI) {
+          const string &Name = PI->first;
+          Functions[Name].push_back(cast<Function>(PI->second));          
+        }
+      }
+
+  bool Changed = false;
+
+  // 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<string, vector<Function*> >::iterator I = Functions.begin(), 
+         E = Functions.end(); I != E; ++I) {
+    vector<Function*> &Functions = I->second;
+    Function *Implementation = 0;     // Find the implementation
+    Function *Concrete = 0;
+    for (unsigned i = 0; i < Functions.size(); ) {
+      if (!Functions[i]->isExternal()) {  // Found an implementation
+        assert(Implementation == 0 && "Multiple definitions of the same"
+               " function. Case not handled yet!");
+        Implementation = Functions[i];
+      } else {
+        // Ignore functions that are never used so they don't cause spurious
+        // warnings... here we will actually DCE the function so that it isn't
+        // used later.
+        //
+        if (Functions[i]->use_size() == 0) {
+          M->getFunctionList().remove(Functions[i]);
+          delete Functions[i];
+          Functions.erase(Functions.begin()+i);
+          Changed = true;
+          ++NumResolved;
+          continue;
+        }
+      }
+      
+      if (Functions[i] && (!Functions[i]->getFunctionType()->isVarArg())) {
+        if (Concrete) {  // Found two different functions types.  Can't choose
+          Concrete = 0;
+          break;
+        }
+        Concrete = Functions[i];
+      }
+      ++i;
+    }
+
+    if (Functions.size() > 1) {         // Found a multiply defined function...
+      // We should find exactly one non-vararg function definition, which is
+      // probably the implementation.  Change all of the function definitions
+      // and uses to use it instead.
+      //
+      if (!Concrete) {
+        cerr << "Warning: Found functions types that are not compatible:\n";
+        for (unsigned i = 0; i < Functions.size(); ++i) {
+          cerr << "\t" << Functions[i]->getType()->getDescription() << " %"
+               << Functions[i]->getName() << "\n";
+        }
+        cerr << "  No linkage of functions named '" << Functions[0]->getName()
+             << "' performed!\n";
+      } else {
+        for (unsigned i = 0; i < Functions.size(); ++i)
+          if (Functions[i] != Concrete) {
+            Function *Old = Functions[i];
+            const FunctionType *OldMT = Old->getFunctionType();
+            const FunctionType *ConcreteMT = Concrete->getFunctionType();
+            bool Broken = false;
+
+            assert(Old->getReturnType() == Concrete->getReturnType() &&
+                   "Differing return types not handled yet!");
+            assert(OldMT->getParamTypes().size() <=
+                   ConcreteMT->getParamTypes().size() &&
+                   "Concrete type must have more specified parameters!");
+
+            // Check to make sure that if there are specified types, that they
+            // match...
+            //
+            for (unsigned i = 0; i < OldMT->getParamTypes().size(); ++i)
+              if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
+                cerr << "Parameter types conflict for" << OldMT
+                     << " and " << ConcreteMT;
+                Broken = true;
+              }
+            if (Broken) break;  // Can't process this one!
+
+
+            // 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> (...)
+            //
+            for (unsigned i = 0; i < Old->use_size(); ) {
+              User *U = *(Old->use_begin()+i);
+              if (CastInst *CI = dyn_cast<CastInst>(U)) {
+                // Convert casts directly
+                assert(CI->getOperand(0) == Old);
+                CI->setOperand(0, Concrete);
+                Changed = true;
+                ++NumResolved;
+              } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
+                // Can only fix up calls TO the argument, not args passed in.
+                if (CI->getCalledValue() == Old) {
+                  ConvertCallTo(CI, Concrete);
+                  Changed = true;
+                  ++NumResolved;
+                } else {
+                  cerr << "Couldn't cleanup this function call, must be an"
+                       << " argument or something!" << CI;
+                  ++i;
+                }
+              } else {
+                cerr << "Cannot convert use of function: " << U << "\n";
+                ++i;
+              }
+            }
+          }
+        }
+    }
+  }
+
+  return Changed;
+}