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-rw-r--r--lib/Transforms/Utils/Local.cpp113
1 files changed, 5 insertions, 108 deletions
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index d03f7a69c5a1..0b48a8fce78b 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -35,111 +35,6 @@
using namespace llvm;
//===----------------------------------------------------------------------===//
-// Local analysis.
-//
-
-/// getUnderlyingObjectWithOffset - Strip off up to MaxLookup GEPs and
-/// bitcasts to get back to the underlying object being addressed, keeping
-/// track of the offset in bytes from the GEPs relative to the result.
-/// This is closely related to Value::getUnderlyingObject but is located
-/// here to avoid making VMCore depend on TargetData.
-static Value *getUnderlyingObjectWithOffset(Value *V, const TargetData *TD,
- uint64_t &ByteOffset,
- unsigned MaxLookup = 6) {
- if (!V->getType()->isPointerTy())
- return V;
- for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
- if (!GEP->hasAllConstantIndices())
- return V;
- SmallVector<Value*, 8> Indices(GEP->op_begin() + 1, GEP->op_end());
- ByteOffset += TD->getIndexedOffset(GEP->getPointerOperandType(),
- &Indices[0], Indices.size());
- V = GEP->getPointerOperand();
- } else if (Operator::getOpcode(V) == Instruction::BitCast) {
- V = cast<Operator>(V)->getOperand(0);
- } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
- if (GA->mayBeOverridden())
- return V;
- V = GA->getAliasee();
- } else {
- return V;
- }
- assert(V->getType()->isPointerTy() && "Unexpected operand type!");
- }
- return V;
-}
-
-/// isSafeToLoadUnconditionally - Return true if we know that executing a load
-/// from this value cannot trap. If it is not obviously safe to load from the
-/// 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,
- unsigned Align, const TargetData *TD) {
- uint64_t ByteOffset = 0;
- Value *Base = V;
- if (TD)
- Base = getUnderlyingObjectWithOffset(V, TD, ByteOffset);
-
- const Type *BaseType = 0;
- 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();
- 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()) {
- BaseType = GV->getType()->getElementType();
- BaseAlign = GV->getAlignment();
- }
- }
-
- 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) &&
- (Align == 0 || (ByteOffset % Align) == 0))
- return true;
- }
- }
-
- // Otherwise, be a little bit aggressive by scanning the local block where we
- // want to check to see if the pointer is already being loaded or stored
- // from/to. If so, the previous load or store would have already trapped,
- // so there is no harm doing an extra load (also, CSE will later eliminate
- // the load entirely).
- BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
-
- while (BBI != E) {
- --BBI;
-
- // If we see a free or a call which may write to memory (i.e. which might do
- // a free) the pointer could be marked invalid.
- if (isa<CallInst>(BBI) && BBI->mayWriteToMemory() &&
- !isa<DbgInfoIntrinsic>(BBI))
- return false;
-
- if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
- if (LI->getOperand(0) == V) return true;
- } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
- if (SI->getOperand(1) == V) return true;
- }
- }
- return false;
-}
-
-
-//===----------------------------------------------------------------------===//
// Local constant propagation.
//
@@ -537,9 +432,11 @@ static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
// Use that list to make another list of common predecessors of BB and Succ
BlockSet CommonPreds;
for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
- PI != PE; ++PI)
- if (BBPreds.count(*PI))
- CommonPreds.insert(*PI);
+ PI != PE; ++PI) {
+ BasicBlock *P = *PI;
+ if (BBPreds.count(P))
+ CommonPreds.insert(P);
+ }
// Shortcut, if there are no common predecessors, merging is always safe
if (CommonPreds.empty())