Introduce ImmutableCallSite, useful for contexts where no mutation

is necessary. Inherits from new templated baseclass CallSiteBase<>
which is highly customizable. Base CallSite on it too, in a configuration
that allows full mutation.
Adapt some call sites in analyses to employ ImmutableCallSite.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100100 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 66 insertions, 64 deletions

diff --git a/lib/Transforms/IPO/DeadArgumentElimination.cpp b/lib/Transforms/IPO/DeadArgumentElimination.cpp
index 4868100..227602d 100644
--- a/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ b/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -129,11 +129,11 @@ namespace {
 
   private:
     Liveness MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses);
-    Liveness SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses,
+    Liveness SurveyUse(Value::const_use_iterator U, UseVector &MaybeLiveUses,
                        unsigned RetValNum = 0);
-    Liveness SurveyUses(Value *V, UseVector &MaybeLiveUses);
+    Liveness SurveyUses(const Value *V, UseVector &MaybeLiveUses);
 
-    void SurveyFunction(Function &F);
+    void SurveyFunction(const Function &F);
     void MarkValue(const RetOrArg &RA, Liveness L,
                    const UseVector &MaybeLiveUses);
     void MarkLive(const RetOrArg &RA);
@@ -310,10 +310,10 @@ DAE::Liveness DAE::MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses) {
 /// RetValNum is the return value number to use when this use is used in a
 /// return instruction. This is used in the recursion, you should always leave
 /// it at 0.
-DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses,
-                             unsigned RetValNum) {
-    User *V = *U;
-    if (ReturnInst *RI = dyn_cast<ReturnInst>(V)) {
+DAE::Liveness DAE::SurveyUse(Value::const_use_iterator U,
+                             UseVector &MaybeLiveUses, unsigned RetValNum) {
+    const User *V = *U;
+    if (const ReturnInst *RI = dyn_cast<ReturnInst>(V)) {
       // The value is returned from a function. It's only live when the
       // function's return value is live. We use RetValNum here, for the case
       // that U is really a use of an insertvalue instruction that uses the
@@ -322,7 +322,7 @@ DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses,
       // We might be live, depending on the liveness of Use.
       return MarkIfNotLive(Use, MaybeLiveUses);
     }
-    if (InsertValueInst *IV = dyn_cast<InsertValueInst>(V)) {
+    if (const InsertValueInst *IV = dyn_cast<InsertValueInst>(V)) {
       if (U.getOperandNo() != InsertValueInst::getAggregateOperandIndex()
           && IV->hasIndices())
         // The use we are examining is inserted into an aggregate. Our liveness
@@ -334,7 +334,7 @@ DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses,
       // we don't change RetValNum, but do survey all our uses.
 
       Liveness Result = MaybeLive;
-      for (Value::use_iterator I = IV->use_begin(),
+      for (Value::const_use_iterator I = IV->use_begin(),
            E = V->use_end(); I != E; ++I) {
         Result = SurveyUse(I, MaybeLiveUses, RetValNum);
         if (Result == Live)
@@ -342,9 +342,9 @@ DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses,
       }
       return Result;
     }
-    CallSite CS = CallSite::get(V);
-    if (CS.getInstruction()) {
-      Function *F = CS.getCalledFunction();
+
+    if (ImmutableCallSite CS = V) {
+      const Function *F = CS.getCalledFunction();
       if (F) {
         // Used in a direct call.
 
@@ -359,7 +359,7 @@ DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses,
           return Live;
 
         assert(CS.getArgument(ArgNo)
-               == CS.getInstruction()->getOperand(U.getOperandNo())
+               == CS->getOperand(U.getOperandNo())
                && "Argument is not where we expected it");
 
         // Value passed to a normal call. It's only live when the corresponding
@@ -378,11 +378,11 @@ DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses,
 /// Adds all uses that cause the result to be MaybeLive to MaybeLiveRetUses. If
 /// the result is Live, MaybeLiveUses might be modified but its content should
 /// be ignored (since it might not be complete).
-DAE::Liveness DAE::SurveyUses(Value *V, UseVector &MaybeLiveUses) {
+DAE::Liveness DAE::SurveyUses(const Value *V, UseVector &MaybeLiveUses) {
   // Assume it's dead (which will only hold if there are no uses at all..).
   Liveness Result = MaybeLive;
   // Check each use.
-  for (Value::use_iterator I = V->use_begin(),
+  for (Value::const_use_iterator I = V->use_begin(),
        E = V->use_end(); I != E; ++I) {
     Result = SurveyUse(I, MaybeLiveUses);
     if (Result == Live)
@@ -399,7 +399,7 @@ DAE::Liveness DAE::SurveyUses(Value *V, UseVector &MaybeLiveUses) {
 // We consider arguments of non-internal functions to be intrinsically alive as
 // well as arguments to functions which have their "address taken".
 //
-void DAE::SurveyFunction(Function &F) {
+void DAE::SurveyFunction(const Function &F) {
   unsigned RetCount = NumRetVals(&F);
   // Assume all return values are dead
   typedef SmallVector<Liveness, 5> RetVals;
@@ -411,8 +411,8 @@ void DAE::SurveyFunction(Function &F) {
   // MaybeLive. Initialized to a list of RetCount empty lists.
   RetUses MaybeLiveRetUses(RetCount);
 
-  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
-    if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
+  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+    if (const ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
       if (RI->getNumOperands() != 0 && RI->getOperand(0)->getType()
           != F.getFunctionType()->getReturnType()) {
         // We don't support old style multiple return values.
@@ -431,17 +431,18 @@ void DAE::SurveyFunction(Function &F) {
   unsigned NumLiveRetVals = 0;
   const Type *STy = dyn_cast<StructType>(F.getReturnType());
   // Loop all uses of the function.
-  for (Value::use_iterator I = F.use_begin(), E = F.use_end(); I != E; ++I) {
+  for (Value::const_use_iterator I = F.use_begin(), E = F.use_end();
+       I != E; ++I) {
     // If the function is PASSED IN as an argument, its address has been
     // taken.
-    CallSite CS = CallSite::get(*I);
-    if (!CS.getInstruction() || !CS.isCallee(I)) {
+    ImmutableCallSite CS(*I);
+    if (!CS || !CS.isCallee(I)) {
       MarkLive(F);
       return;
     }
 
     // If this use is anything other than a call site, the function is alive.
-    Instruction *TheCall = CS.getInstruction();
+    const Instruction *TheCall = CS.getInstruction();
     if (!TheCall) {   // Not a direct call site?
       MarkLive(F);
       return;
@@ -454,9 +455,9 @@ void DAE::SurveyFunction(Function &F) {
     if (NumLiveRetVals != RetCount) {
       if (STy) {
         // Check all uses of the return value.
-        for (Value::use_iterator I = TheCall->use_begin(),
+        for (Value::const_use_iterator I = TheCall->use_begin(),
              E = TheCall->use_end(); I != E; ++I) {
-          ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(*I);
+          const ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(*I);
           if (Ext && Ext->hasIndices()) {
             // This use uses a part of our return value, survey the uses of
             // that part and store the results for this index only.
@@ -493,7 +494,7 @@ void DAE::SurveyFunction(Function &F) {
   // Now, check all of our arguments.
   unsigned i = 0;
   UseVector MaybeLiveArgUses;
-  for (Function::arg_iterator AI = F.arg_begin(),
+  for (Function::const_arg_iterator AI = F.arg_begin(),
        E = F.arg_end(); AI != E; ++AI, ++i) {
     // See what the effect of this use is (recording any uses that cause
     // MaybeLive in MaybeLiveArgUses).
@@ -690,7 +691,8 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
     AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
 
   // Reconstruct the AttributesList based on the vector we constructed.
-  AttrListPtr NewPAL = AttrListPtr::get(AttributesVec.begin(), AttributesVec.end());
+  AttrListPtr NewPAL = AttrListPtr::get(AttributesVec.begin(),
+                                        AttributesVec.end());
 
   // Work around LLVM bug PR56: the CWriter cannot emit varargs functions which
   // have zero fixed arguments.
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index d8e97a2..ddff5ef 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -119,7 +119,7 @@ struct GlobalStatus {
   /// null/false.  When the first accessing function is noticed, it is recorded.
   /// When a second different accessing function is noticed,
   /// HasMultipleAccessingFunctions is set to true.
-  Function *AccessingFunction;
+  const Function *AccessingFunction;
   bool HasMultipleAccessingFunctions;
 
   /// HasNonInstructionUser - Set to true if this global has a user that is not
@@ -140,11 +140,11 @@ struct GlobalStatus {
 // by constants itself.  Note that constants cannot be cyclic, so this test is
 // pretty easy to implement recursively.
 //
-static bool SafeToDestroyConstant(Constant *C) {
+static bool SafeToDestroyConstant(const Constant *C) {
   if (isa<GlobalValue>(C)) return false;
 
-  for (Value::use_iterator UI = C->use_begin(), E = C->use_end(); UI != E; ++UI)
-    if (Constant *CU = dyn_cast<Constant>(*UI)) {
+  for (Value::const_use_iterator UI = C->use_begin(), E = C->use_end(); UI != E; ++UI)
+    if (const Constant *CU = dyn_cast<Constant>(*UI)) {
       if (!SafeToDestroyConstant(CU)) return false;
     } else
       return false;
@@ -156,26 +156,26 @@ static bool SafeToDestroyConstant(Constant *C) {
 /// structure.  If the global has its address taken, return true to indicate we
 /// can't do anything with it.
 ///
-static bool AnalyzeGlobal(Value *V, GlobalStatus &GS,
-                          SmallPtrSet<PHINode*, 16> &PHIUsers) {
-  for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
-    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
+static bool AnalyzeGlobal(const Value *V, GlobalStatus &GS,
+                          SmallPtrSet<const PHINode*, 16> &PHIUsers) {
+  for (Value::const_use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
+    if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
       GS.HasNonInstructionUser = true;
 
       if (AnalyzeGlobal(CE, GS, PHIUsers)) return true;
 
-    } else if (Instruction *I = dyn_cast<Instruction>(*UI)) {
+    } else if (const Instruction *I = dyn_cast<Instruction>(*UI)) {
       if (!GS.HasMultipleAccessingFunctions) {
-        Function *F = I->getParent()->getParent();
+        const Function *F = I->getParent()->getParent();
         if (GS.AccessingFunction == 0)
           GS.AccessingFunction = F;
         else if (GS.AccessingFunction != F)
           GS.HasMultipleAccessingFunctions = true;
       }
-      if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+      if (const LoadInst *LI = dyn_cast<LoadInst>(I)) {
         GS.isLoaded = true;
         if (LI->isVolatile()) return true;  // Don't hack on volatile loads.
-      } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+      } else if (const StoreInst *SI = dyn_cast<StoreInst>(I)) {
         // Don't allow a store OF the address, only stores TO the address.
         if (SI->getOperand(0) == V) return true;
 
@@ -185,14 +185,13 @@ static bool AnalyzeGlobal(Value *V, GlobalStatus &GS,
         // value, not an aggregate), keep more specific information about
         // stores.
         if (GS.StoredType != GlobalStatus::isStored) {
-          if (GlobalVariable *GV = dyn_cast<GlobalVariable>(SI->getOperand(1))){
+          if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(SI->getOperand(1))){
             Value *StoredVal = SI->getOperand(0);
             if (StoredVal == GV->getInitializer()) {
               if (GS.StoredType < GlobalStatus::isInitializerStored)
                 GS.StoredType = GlobalStatus::isInitializerStored;
             } else if (isa<LoadInst>(StoredVal) &&
                        cast<LoadInst>(StoredVal)->getOperand(0) == GV) {
-              // G = G
               if (GS.StoredType < GlobalStatus::isInitializerStored)
                 GS.StoredType = GlobalStatus::isInitializerStored;
             } else if (GS.StoredType < GlobalStatus::isStoredOnce) {
@@ -212,7 +211,7 @@ static bool AnalyzeGlobal(Value *V, GlobalStatus &GS,
         if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
       } else if (isa<SelectInst>(I)) {
         if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
-      } else if (PHINode *PN = dyn_cast<PHINode>(I)) {
+      } else if (const PHINode *PN = dyn_cast<PHINode>(I)) {
         // PHI nodes we can check just like select or GEP instructions, but we
         // have to be careful about infinite recursion.
         if (PHIUsers.insert(PN))  // Not already visited.
@@ -230,7 +229,7 @@ static bool AnalyzeGlobal(Value *V, GlobalStatus &GS,
       } else {
         return true;  // Any other non-load instruction might take address!
       }
-    } else if (Constant *C = dyn_cast<Constant>(*UI)) {
+    } else if (const Constant *C = dyn_cast<Constant>(*UI)) {
       GS.HasNonInstructionUser = true;
       // We might have a dead and dangling constant hanging off of here.
       if (!SafeToDestroyConstant(C))
@@ -1029,23 +1028,23 @@ static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
 /// LoadUsesSimpleEnoughForHeapSRA - Verify that all uses of V (a load, or a phi
 /// of a load) are simple enough to perform heap SRA on.  This permits GEP's
 /// that index through the array and struct field, icmps of null, and PHIs.
-static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
-                              SmallPtrSet<PHINode*, 32> &LoadUsingPHIs,
-                              SmallPtrSet<PHINode*, 32> &LoadUsingPHIsPerLoad) {
+static bool LoadUsesSimpleEnoughForHeapSRA(const Value *V,
+                              SmallPtrSet<const PHINode*, 32> &LoadUsingPHIs,
+                              SmallPtrSet<const PHINode*, 32> &LoadUsingPHIsPerLoad) {
   // We permit two users of the load: setcc comparing against the null
   // pointer, and a getelementptr of a specific form.
-  for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
-    Instruction *User = cast<Instruction>(*UI);
+  for (Value::const_use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
+    const Instruction *User = cast<Instruction>(*UI);
     
     // Comparison against null is ok.
-    if (ICmpInst *ICI = dyn_cast<ICmpInst>(User)) {
+    if (const ICmpInst *ICI = dyn_cast<ICmpInst>(User)) {
       if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
         return false;
       continue;
     }
     
     // getelementptr is also ok, but only a simple form.
-    if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
+    if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
       // Must index into the array and into the struct.
       if (GEPI->getNumOperands() < 3)
         return false;
@@ -1054,7 +1053,7 @@ static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
       continue;
     }
     
-    if (PHINode *PN = dyn_cast<PHINode>(User)) {
+    if (const PHINode *PN = dyn_cast<PHINode>(User)) {
       if (!LoadUsingPHIsPerLoad.insert(PN))
         // This means some phi nodes are dependent on each other.
         // Avoid infinite looping!
@@ -1081,13 +1080,13 @@ static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
 
 /// AllGlobalLoadUsesSimpleEnoughForHeapSRA - If all users of values loaded from
 /// GV are simple enough to perform HeapSRA, return true.
-static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV,
+static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(const GlobalVariable *GV,
                                                     Instruction *StoredVal) {
-  SmallPtrSet<PHINode*, 32> LoadUsingPHIs;
-  SmallPtrSet<PHINode*, 32> LoadUsingPHIsPerLoad;
-  for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E; 
+  SmallPtrSet<const PHINode*, 32> LoadUsingPHIs;
+  SmallPtrSet<const PHINode*, 32> LoadUsingPHIsPerLoad;
+  for (Value::const_use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E; 
        ++UI)
-    if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
+    if (const LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
       if (!LoadUsesSimpleEnoughForHeapSRA(LI, LoadUsingPHIs,
                                           LoadUsingPHIsPerLoad))
         return false;
@@ -1099,16 +1098,16 @@ static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV,
   // that all inputs the to the PHI nodes are in the same equivalence sets. 
   // Check to verify that all operands of the PHIs are either PHIS that can be
   // transformed, loads from GV, or MI itself.
-  for (SmallPtrSet<PHINode*, 32>::iterator I = LoadUsingPHIs.begin(),
+  for (SmallPtrSet<const PHINode*, 32>::const_iterator I = LoadUsingPHIs.begin(),
        E = LoadUsingPHIs.end(); I != E; ++I) {
-    PHINode *PN = *I;
+    const PHINode *PN = *I;
     for (unsigned op = 0, e = PN->getNumIncomingValues(); op != e; ++op) {
       Value *InVal = PN->getIncomingValue(op);
       
       // PHI of the stored value itself is ok.
       if (InVal == StoredVal) continue;
       
-      if (PHINode *InPN = dyn_cast<PHINode>(InVal)) {
+      if (const PHINode *InPN = dyn_cast<PHINode>(InVal)) {
         // One of the PHIs in our set is (optimistically) ok.
         if (LoadUsingPHIs.count(InPN))
           continue;
@@ -1116,7 +1115,7 @@ static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV,
       }
       
       // Load from GV is ok.
-      if (LoadInst *LI = dyn_cast<LoadInst>(InVal))
+      if (const LoadInst *LI = dyn_cast<LoadInst>(InVal))
         if (LI->getOperand(0) == GV)
           continue;
       
@@ -1664,7 +1663,7 @@ static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
 /// it if possible.  If we make a change, return true.
 bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
                                       Module::global_iterator &GVI) {
-  SmallPtrSet<PHINode*, 16> PHIUsers;
+  SmallPtrSet<const PHINode*, 16> PHIUsers;
   GlobalStatus GS;
   GV->removeDeadConstantUsers();
 
@@ -1715,12 +1714,13 @@ bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
         GS.AccessingFunction->hasExternalLinkage() &&
         GV->getType()->getAddressSpace() == 0) {
       DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV);
-      Instruction* FirstI = GS.AccessingFunction->getEntryBlock().begin();
+      Instruction& FirstI = const_cast<Instruction&>(*GS.AccessingFunction
+                                                     ->getEntryBlock().begin());
       const Type* ElemTy = GV->getType()->getElementType();
       // FIXME: Pass Global's alignment when globals have alignment
-      AllocaInst* Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), FirstI);
+      AllocaInst* Alloca = new AllocaInst(ElemTy, NULL, GV->getName(), &FirstI);
       if (!isa<UndefValue>(GV->getInitializer()))
-        new StoreInst(GV->getInitializer(), Alloca, FirstI);
+        new StoreInst(GV->getInitializer(), Alloca, &FirstI);
 
       GV->replaceAllUsesWith(Alloca);
       GV->eraseFromParent();
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index b15df2a..546b7b6 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -1717,7 +1717,7 @@ static bool AddressIsTaken(const GlobalValue *GV) {
         return true;  // Storing addr of GV.
     } else if (isa<InvokeInst>(U) || isa<CallInst>(U)) {
       // Make sure we are calling the function, not passing the address.
-      CallSite CS((Instruction*)U);
+      ImmutableCallSite CS(cast<Instruction>(U));
       if (!CS.isCallee(UI))
         return true;
     } else if (const LoadInst *LI = dyn_cast<LoadInst>(U)) {