#define DEBUG_TYPE "scalarrepl"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Constants.h"
-#include "llvm/DIBuilder.h"
-#include "llvm/DebugInfo.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Function.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/IRBuilder.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
-#include "llvm/Operator.h"
-#include "llvm/Pass.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/DIBuilder.h"
+#include "llvm/DebugInfo.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Operator.h"
+#include "llvm/Pass.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
STATISTIC(NumPromoted, "Number of allocas promoted");
STATISTIC(NumAdjusted, "Number of scalar allocas adjusted to allow promotion");
STATISTIC(NumConverted, "Number of aggregates converted to scalar");
-STATISTIC(NumGlobals, "Number of allocas copied from constant global");
namespace {
struct SROA : public FunctionPass {
private:
bool HasDomTree;
- TargetData *TD;
+ DataLayout *TD;
/// DeadInsts - Keep track of instructions we have made dead, so that
/// we can remove them after we are done working.
void RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI,
SmallVector<AllocaInst*, 32> &NewElts);
bool ShouldAttemptScalarRepl(AllocaInst *AI);
-
- static MemTransferInst *isOnlyCopiedFromConstantGlobal(
- AllocaInst *AI, SmallVector<Instruction*, 4> &ToDelete);
};
// SROA_DT - SROA that uses DominatorTree.
class ConvertToScalarInfo {
/// AllocaSize - The size of the alloca being considered in bytes.
unsigned AllocaSize;
- const TargetData &TD;
+ const DataLayout &TD;
unsigned ScalarLoadThreshold;
/// IsNotTrivial - This is set to true if there is some access to the object
bool HadDynamicAccess;
public:
- explicit ConvertToScalarInfo(unsigned Size, const TargetData &td,
+ explicit ConvertToScalarInfo(unsigned Size, const DataLayout &td,
unsigned SLT)
: AllocaSize(Size), TD(td), ScalarLoadThreshold(SLT), IsNotTrivial(false),
ScalarKind(Unknown), VectorTy(0), HadNonMemTransferAccess(false),
bool SROA::runOnFunction(Function &F) {
- TD = getAnalysisIfAvailable<TargetData>();
+ TD = getAnalysisIfAvailable<DataLayout>();
bool Changed = performPromotion(F);
- // FIXME: ScalarRepl currently depends on TargetData more than it
+ // FIXME: ScalarRepl currently depends on DataLayout more than it
// theoretically needs to. It should be refactored in order to support
// target-independent IR. Until this is done, just skip the actual
// scalar-replacement portion of this pass.
///
/// We can do this to a select if its only uses are loads and if the operand to
/// the select can be loaded unconditionally.
-static bool isSafeSelectToSpeculate(SelectInst *SI, const TargetData *TD) {
+static bool isSafeSelectToSpeculate(SelectInst *SI, const DataLayout *TD) {
bool TDerefable = SI->getTrueValue()->isDereferenceablePointer();
bool FDerefable = SI->getFalseValue()->isDereferenceablePointer();
///
/// We can do this to a select if its only uses are loads and if the operand to
/// the select can be loaded unconditionally.
-static bool isSafePHIToSpeculate(PHINode *PN, const TargetData *TD) {
+static bool isSafePHIToSpeculate(PHINode *PN, const DataLayout *TD) {
// For now, we can only do this promotion if the load is in the same block as
// the PHI, and if there are no stores between the phi and load.
// TODO: Allow recursive phi users.
/// direct (non-volatile) loads and stores to it. If the alloca is close but
/// not quite there, this will transform the code to allow promotion. As such,
/// it is a non-pure predicate.
-static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const TargetData *TD) {
+static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const DataLayout *TD) {
SetVector<Instruction*, SmallVector<Instruction*, 4>,
SmallPtrSet<Instruction*, 4> > InstsToRewrite;
return false;
}
-/// getPointeeAlignment - Compute the minimum alignment of the value pointed
-/// to by the given pointer.
-static unsigned getPointeeAlignment(Value *V, const TargetData &TD) {
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- if (CE->getOpcode() == Instruction::BitCast ||
- (CE->getOpcode() == Instruction::GetElementPtr &&
- cast<GEPOperator>(CE)->hasAllZeroIndices()))
- return getPointeeAlignment(CE->getOperand(0), TD);
-
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
- if (!GV->isDeclaration())
- return TD.getPreferredAlignment(GV);
-
- if (PointerType *PT = dyn_cast<PointerType>(V->getType()))
- return TD.getABITypeAlignment(PT->getElementType());
-
- return 0;
-}
-
-
// performScalarRepl - This algorithm is a simple worklist driven algorithm,
// which runs on all of the alloca instructions in the function, removing them
// if they are only used by getelementptr instructions.
if (AI->isArrayAllocation() || !AI->getAllocatedType()->isSized())
continue;
- // Check to see if this allocation is only modified by a memcpy/memmove from
- // a constant global whose alignment is equal to or exceeds that of the
- // allocation. If this is the case, we can change all users to use
- // the constant global instead. This is commonly produced by the CFE by
- // constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
- // is only subsequently read.
- SmallVector<Instruction *, 4> ToDelete;
- if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(AI, ToDelete)) {
- if (AI->getAlignment() <= getPointeeAlignment(Copy->getSource(), *TD)) {
- DEBUG(dbgs() << "Found alloca equal to global: " << *AI << '\n');
- DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
- for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
- ToDelete[i]->eraseFromParent();
- Constant *TheSrc = cast<Constant>(Copy->getSource());
- AI->replaceAllUsesWith(ConstantExpr::getBitCast(TheSrc, AI->getType()));
- Copy->eraseFromParent(); // Don't mutate the global.
- AI->eraseFromParent();
- ++NumGlobals;
- Changed = true;
- continue;
- }
- }
-
// Check to see if we can perform the core SROA transformation. We cannot
// transform the allocation instruction if it is an array allocation
// (allocations OF arrays are ok though), and an allocation of a scalar
continue;
ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPIt.getOperand());
- if (!IdxVal) {
- // Non constant GEPs are only a problem on arrays, structs, and pointers
- // Vectors can be dynamically indexed.
- // FIXME: Add support for dynamic indexing on arrays. This should be
- // ok on any subarrays of the alloca array, eg, a[0][i] is ok, but a[i][0]
- // isn't.
- if (!(*GEPIt)->isVectorTy())
- return MarkUnsafe(Info, GEPI);
- NonConstant = true;
- NonConstantIdxSize = TD->getTypeAllocSize(*GEPIt);
- }
+ if (!IdxVal)
+ return MarkUnsafe(Info, GEPI);
}
// Compute the offset due to this GEP and check if the alloca has a
/// HasPadding - Return true if the specified type has any structure or
/// alignment padding in between the elements that would be split apart
/// by SROA; return false otherwise.
-static bool HasPadding(Type *Ty, const TargetData &TD) {
+static bool HasPadding(Type *Ty, const DataLayout &TD) {
if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
Ty = ATy->getElementType();
return TD.getTypeSizeInBits(Ty) != TD.getTypeAllocSizeInBits(Ty);
return true;
}
-
-
-
-/// PointsToConstantGlobal - Return true if V (possibly indirectly) points to
-/// some part of a constant global variable. This intentionally only accepts
-/// constant expressions because we don't can't rewrite arbitrary instructions.
-static bool PointsToConstantGlobal(Value *V) {
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
- return GV->isConstant();
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- if (CE->getOpcode() == Instruction::BitCast ||
- CE->getOpcode() == Instruction::GetElementPtr)
- return PointsToConstantGlobal(CE->getOperand(0));
- return false;
-}
-
-/// isOnlyCopiedFromConstantGlobal - Recursively walk the uses of a (derived)
-/// pointer to an alloca. Ignore any reads of the pointer, return false if we
-/// see any stores or other unknown uses. If we see pointer arithmetic, keep
-/// track of whether it moves the pointer (with isOffset) but otherwise traverse
-/// the uses. If we see a memcpy/memmove that targets an unoffseted pointer to
-/// the alloca, and if the source pointer is a pointer to a constant global, we
-/// can optimize this.
-static bool
-isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
- bool isOffset,
- SmallVector<Instruction *, 4> &LifetimeMarkers) {
- // We track lifetime intrinsics as we encounter them. If we decide to go
- // ahead and replace the value with the global, this lets the caller quickly
- // eliminate the markers.
-
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
- User *U = cast<Instruction>(*UI);
-
- if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
- // Ignore non-volatile loads, they are always ok.
- if (!LI->isSimple()) return false;
- continue;
- }
-
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
- // If uses of the bitcast are ok, we are ok.
- if (!isOnlyCopiedFromConstantGlobal(BCI, TheCopy, isOffset,
- LifetimeMarkers))
- return false;
- continue;
- }
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
- // If the GEP has all zero indices, it doesn't offset the pointer. If it
- // doesn't, it does.
- if (!isOnlyCopiedFromConstantGlobal(GEP, TheCopy,
- isOffset || !GEP->hasAllZeroIndices(),
- LifetimeMarkers))
- return false;
- continue;
- }
-
- if (CallSite CS = U) {
- // If this is the function being called then we treat it like a load and
- // ignore it.
- if (CS.isCallee(UI))
- continue;
-
- // If this is a readonly/readnone call site, then we know it is just a
- // load (but one that potentially returns the value itself), so we can
- // ignore it if we know that the value isn't captured.
- unsigned ArgNo = CS.getArgumentNo(UI);
- if (CS.onlyReadsMemory() &&
- (CS.getInstruction()->use_empty() || CS.doesNotCapture(ArgNo)))
- continue;
-
- // If this is being passed as a byval argument, the caller is making a
- // copy, so it is only a read of the alloca.
- if (CS.isByValArgument(ArgNo))
- continue;
- }
-
- // Lifetime intrinsics can be handled by the caller.
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) {
- if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
- II->getIntrinsicID() == Intrinsic::lifetime_end) {
- assert(II->use_empty() && "Lifetime markers have no result to use!");
- LifetimeMarkers.push_back(II);
- continue;
- }
- }
-
- // If this is isn't our memcpy/memmove, reject it as something we can't
- // handle.
- MemTransferInst *MI = dyn_cast<MemTransferInst>(U);
- if (MI == 0)
- return false;
-
- // If the transfer is using the alloca as a source of the transfer, then
- // ignore it since it is a load (unless the transfer is volatile).
- if (UI.getOperandNo() == 1) {
- if (MI->isVolatile()) return false;
- continue;
- }
-
- // If we already have seen a copy, reject the second one.
- if (TheCopy) return false;
-
- // If the pointer has been offset from the start of the alloca, we can't
- // safely handle this.
- if (isOffset) return false;
-
- // If the memintrinsic isn't using the alloca as the dest, reject it.
- if (UI.getOperandNo() != 0) return false;
-
- // If the source of the memcpy/move is not a constant global, reject it.
- if (!PointsToConstantGlobal(MI->getSource()))
- return false;
-
- // Otherwise, the transform is safe. Remember the copy instruction.
- TheCopy = MI;
- }
- return true;
-}
-
-/// isOnlyCopiedFromConstantGlobal - Return true if the specified alloca is only
-/// modified by a copy from a constant global. If we can prove this, we can
-/// replace any uses of the alloca with uses of the global directly.
-MemTransferInst *
-SROA::isOnlyCopiedFromConstantGlobal(AllocaInst *AI,
- SmallVector<Instruction*, 4> &ToDelete) {
- MemTransferInst *TheCopy = 0;
- if (::isOnlyCopiedFromConstantGlobal(AI, TheCopy, false, ToDelete))
- return TheCopy;
- return 0;
-}
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