Re-commit my previous SSAUpdater changes. The previous version naively tried

[oota-llvm.git] / lib / Transforms / Utils / Local.cpp

diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 425f5572969247c8cb68f9b579d8f1d345bb32d7..d03f7a69c5a1df18fa8da929bad09c33930e4431 100644 (file)
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -46,7 +46,7 @@ using namespace llvm;
 static Value *getUnderlyingObjectWithOffset(Value *V, const TargetData *TD,
                                             uint64_t &ByteOffset,
                                             unsigned MaxLookup = 6) {
-  if (!isa<PointerType>(V->getType()))
+  if (!V->getType()->isPointerTy())
     return V;
   for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
@@ -65,7 +65,7 @@ static Value *getUnderlyingObjectWithOffset(Value *V, const TargetData *TD,
     } else {
       return V;
     }
-    assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
+    assert(V->getType()->isPointerTy() && "Unexpected operand type!");
   }
   return V;
 }
@@ -75,31 +75,40 @@ static Value *getUnderlyingObjectWithOffset(Value *V, const TargetData *TD,
 /// specified pointer, we do a quick local scan of the basic block containing
 /// ScanFrom, to determine if the address is already accessed.
 bool llvm::isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom,
-                                       const TargetData *TD) {
+                                       unsigned Align, const TargetData *TD) {
   uint64_t ByteOffset = 0;
   Value *Base = V;
   if (TD)
     Base = getUnderlyingObjectWithOffset(V, TD, ByteOffset);
 
   const Type *BaseType = 0;
-  if (const AllocaInst *AI = dyn_cast<AllocaInst>(Base))
-    // If it is an alloca it is always safe to load from.
+  unsigned BaseAlign = 0;
+  if (const AllocaInst *AI = dyn_cast<AllocaInst>(Base)) {
+    // An alloca is safe to load from as load as it is suitably aligned.
     BaseType = AI->getAllocatedType();
-  else if (const GlobalValue *GV = dyn_cast<GlobalValue>(Base)) {
+    BaseAlign = AI->getAlignment();
+  } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(Base)) {
     // Global variables are safe to load from but their size cannot be
     // guaranteed if they are overridden.
-    if (!isa<GlobalAlias>(GV) && !GV->mayBeOverridden())
+    if (!isa<GlobalAlias>(GV) && !GV->mayBeOverridden()) {
       BaseType = GV->getType()->getElementType();
+      BaseAlign = GV->getAlignment();
+    }
   }
 
-  if (BaseType) {
-    if (!TD)
-      return true; // Loading directly from an alloca or global is OK.
-    if (BaseType->isSized()) {
+  if (BaseType && BaseType->isSized()) {
+    if (TD && BaseAlign == 0)
+      BaseAlign = TD->getPrefTypeAlignment(BaseType);
+
+    if (Align <= BaseAlign) {
+      if (!TD)
+        return true; // Loading directly from an alloca or global is OK.
+
       // Check if the load is within the bounds of the underlying object.
       const PointerType *AddrTy = cast<PointerType>(V->getType());
       uint64_t LoadSize = TD->getTypeStoreSize(AddrTy->getElementType());
-      if (ByteOffset + LoadSize <= TD->getTypeAllocSize(BaseType))
+      if (ByteOffset + LoadSize <= TD->getTypeAllocSize(BaseType) &&
+          (Align == 0 || (ByteOffset % Align) == 0))
         return true;
     }
   }
@@ -481,6 +490,17 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, Pass *P) {
   // Splice all the instructions from PredBB to DestBB.
   PredBB->getTerminator()->eraseFromParent();
   DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
+
+  // Zap anything that took the address of DestBB.  Not doing this will give the
+  // address an invalid value.
+  if (DestBB->hasAddressTaken()) {
+    BlockAddress *BA = BlockAddress::get(DestBB);
+    Constant *Replacement =
+      ConstantInt::get(llvm::Type::getInt32Ty(BA->getContext()), 1);
+    BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement,
+                                                     BA->getType()));
+    BA->destroyConstant();
+  }
   
   // Anything that branched to PredBB now branches to DestBB.
   PredBB->replaceAllUsesWith(DestBB);