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
diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index fd3d534..c533d6e 100644
--- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -13,6 +13,7 @@
#include "InstCombine.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/Analysis/Loads.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index ca8ab49..eb13df5 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -35,6 +35,7 @@
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Analysis/PHITransAddr.h"
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index df05b71..0352c6e 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -18,6 +18,7 @@
#include "llvm/Pass.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LazyValueInfo.h"
+#include "llvm/Analysis/Loads.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
diff --git a/lib/Transforms/Scalar/TailRecursionElimination.cpp b/lib/Transforms/Scalar/TailRecursionElimination.cpp
index 5ad5de2..f8d051e 100644
--- a/lib/Transforms/Scalar/TailRecursionElimination.cpp
+++ b/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -60,6 +60,7 @@
#include "llvm/Pass.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/InlineCost.h"
+#include "llvm/Analysis/Loads.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/CFG.h"
#include "llvm/ADT/Statistic.h"
diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
index 2f1ae00..ec625b4 100644
--- a/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -558,121 +558,3 @@
}
-
-
-
-/// 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 d03f7a6..b9fcfd5 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.
//