Move FindAvailableLoadedValue isSafeToLoadUnconditionally out of

lib/Transforms/Utils and into lib/Analysis so that Analysis passes
can use them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104949 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 0 insertions, 223 deletions

diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index 2f1ae005a4..ec625b4cbb 100644
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -558,121 +558,3 @@ void llvm::FindFunctionBackedges(const Function &F,
   
   
 }
-
-
-
-/// AreEquivalentAddressValues - Test if A and B will obviously have the same
-/// value. This includes recognizing that %t0 and %t1 will have the same
-/// value in code like this:
-///   %t0 = getelementptr \@a, 0, 3
-///   store i32 0, i32* %t0
-///   %t1 = getelementptr \@a, 0, 3
-///   %t2 = load i32* %t1
-///
-static bool AreEquivalentAddressValues(const Value *A, const Value *B) {
-  // Test if the values are trivially equivalent.
-  if (A == B) return true;
-  
-  // Test if the values come from identical arithmetic instructions.
-  // Use isIdenticalToWhenDefined instead of isIdenticalTo because
-  // this function is only used when one address use dominates the
-  // other, which means that they'll always either have the same
-  // value or one of them will have an undefined value.
-  if (isa<BinaryOperator>(A) || isa<CastInst>(A) ||
-      isa<PHINode>(A) || isa<GetElementPtrInst>(A))
-    if (const Instruction *BI = dyn_cast<Instruction>(B))
-      if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
-        return true;
-  
-  // Otherwise they may not be equivalent.
-  return false;
-}
-
-/// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at the
-/// instruction before ScanFrom) checking to see if we have the value at the
-/// memory address *Ptr locally available within a small number of instructions.
-/// If the value is available, return it.
-///
-/// If not, return the iterator for the last validated instruction that the 
-/// value would be live through.  If we scanned the entire block and didn't find
-/// something that invalidates *Ptr or provides it, ScanFrom would be left at
-/// begin() and this returns null.  ScanFrom could also be left 
-///
-/// MaxInstsToScan specifies the maximum instructions to scan in the block.  If
-/// it is set to 0, it will scan the whole block. You can also optionally
-/// specify an alias analysis implementation, which makes this more precise.
-Value *llvm::FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB,
-                                      BasicBlock::iterator &ScanFrom,
-                                      unsigned MaxInstsToScan,
-                                      AliasAnalysis *AA) {
-  if (MaxInstsToScan == 0) MaxInstsToScan = ~0U;
-
-  // If we're using alias analysis to disambiguate get the size of *Ptr.
-  unsigned AccessSize = 0;
-  if (AA) {
-    const Type *AccessTy = cast<PointerType>(Ptr->getType())->getElementType();
-    AccessSize = AA->getTypeStoreSize(AccessTy);
-  }
-  
-  while (ScanFrom != ScanBB->begin()) {
-    // We must ignore debug info directives when counting (otherwise they
-    // would affect codegen).
-    Instruction *Inst = --ScanFrom;
-    if (isa<DbgInfoIntrinsic>(Inst))
-      continue;
-
-    // Restore ScanFrom to expected value in case next test succeeds
-    ScanFrom++;
-   
-    // Don't scan huge blocks.
-    if (MaxInstsToScan-- == 0) return 0;
-    
-    --ScanFrom;
-    // If this is a load of Ptr, the loaded value is available.
-    if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
-      if (AreEquivalentAddressValues(LI->getOperand(0), Ptr))
-        return LI;
-    
-    if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
-      // If this is a store through Ptr, the value is available!
-      if (AreEquivalentAddressValues(SI->getOperand(1), Ptr))
-        return SI->getOperand(0);
-      
-      // If Ptr is an alloca and this is a store to a different alloca, ignore
-      // the store.  This is a trivial form of alias analysis that is important
-      // for reg2mem'd code.
-      if ((isa<AllocaInst>(Ptr) || isa<GlobalVariable>(Ptr)) &&
-          (isa<AllocaInst>(SI->getOperand(1)) ||
-           isa<GlobalVariable>(SI->getOperand(1))))
-        continue;
-      
-      // If we have alias analysis and it says the store won't modify the loaded
-      // value, ignore the store.
-      if (AA &&
-          (AA->getModRefInfo(SI, Ptr, AccessSize) & AliasAnalysis::Mod) == 0)
-        continue;
-      
-      // Otherwise the store that may or may not alias the pointer, bail out.
-      ++ScanFrom;
-      return 0;
-    }
-    
-    // If this is some other instruction that may clobber Ptr, bail out.
-    if (Inst->mayWriteToMemory()) {
-      // If alias analysis claims that it really won't modify the load,
-      // ignore it.
-      if (AA &&
-          (AA->getModRefInfo(Inst, Ptr, AccessSize) & AliasAnalysis::Mod) == 0)
-        continue;
-      
-      // May modify the pointer, bail out.
-      ++ScanFrom;
-      return 0;
-    }
-  }
-  
-  // Got to the start of the block, we didn't find it, but are done for this
-  // block.
-  return 0;
-}
-
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index d03f7a69c5..b9fcfd5f5f 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.
 //