//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "dse"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CaptureTracking.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
+#define DEBUG_TYPE "dse"
+
STATISTIC(NumFastStores, "Number of stores deleted");
STATISTIC(NumFastOther , "Number of other instrs removed");
const TargetLibraryInfo *TLI;
static char ID; // Pass identification, replacement for typeid
- DSE() : FunctionPass(ID), AA(0), MD(0), DT(0) {
+ DSE() : FunctionPass(ID), AA(nullptr), MD(nullptr), DT(nullptr) {
initializeDSEPass(*PassRegistry::getPassRegistry());
}
- virtual bool runOnFunction(Function &F) {
+ bool runOnFunction(Function &F) override {
+ if (skipOptnoneFunction(F))
+ return false;
+
AA = &getAnalysis<AliasAnalysis>();
MD = &getAnalysis<MemoryDependenceAnalysis>();
- DT = &getAnalysis<DominatorTree>();
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
TLI = AA->getTargetLibraryInfo();
bool Changed = false;
if (DT->isReachableFromEntry(I))
Changed |= runOnBasicBlock(*I);
- AA = 0; MD = 0; DT = 0;
+ AA = nullptr; MD = nullptr; DT = nullptr;
return Changed;
}
void RemoveAccessedObjects(const AliasAnalysis::Location &LoadedLoc,
SmallSetVector<Value*, 16> &DeadStackObjects);
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
- AU.addRequired<DominatorTree>();
+ AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<AliasAnalysis>();
AU.addRequired<MemoryDependenceAnalysis>();
AU.addPreserved<AliasAnalysis>();
- AU.addPreserved<DominatorTree>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
AU.addPreserved<MemoryDependenceAnalysis>();
}
};
char DSE::ID = 0;
INITIALIZE_PASS_BEGIN(DSE, "dse", "Dead Store Elimination", false, false)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_END(DSE, "dse", "Dead Store Elimination", false, false)
/// If ValueSet is non-null, remove any deleted instructions from it as well.
///
static void DeleteDeadInstruction(Instruction *I,
- MemoryDependenceAnalysis &MD,
- const TargetLibraryInfo *TLI,
- SmallSetVector<Value*, 16> *ValueSet = 0) {
+ MemoryDependenceAnalysis &MD,
+ const TargetLibraryInfo *TLI,
+ SmallSetVector<Value*, 16> *ValueSet = nullptr) {
SmallVector<Instruction*, 32> NowDeadInsts;
NowDeadInsts.push_back(I);
for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) {
Value *Op = DeadInst->getOperand(op);
- DeadInst->setOperand(op, 0);
+ DeadInst->setOperand(op, nullptr);
// If this operand just became dead, add it to the NowDeadInsts list.
if (!Op->use_empty()) continue;
/// describe the memory operations for this instruction.
static AliasAnalysis::Location
getLocForWrite(Instruction *Inst, AliasAnalysis &AA) {
+ const DataLayout *DL = AA.getDataLayout();
if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
return AA.getLocation(SI);
// If we don't have target data around, an unknown size in Location means
// that we should use the size of the pointee type. This isn't valid for
// memset/memcpy, which writes more than an i8.
- if (Loc.Size == AliasAnalysis::UnknownSize && AA.getDataLayout() == 0)
+ if (Loc.Size == AliasAnalysis::UnknownSize && DL == nullptr)
return AliasAnalysis::Location();
return Loc;
}
IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst);
- if (II == 0) return AliasAnalysis::Location();
+ if (!II) return AliasAnalysis::Location();
switch (II->getIntrinsicID()) {
default: return AliasAnalysis::Location(); // Unhandled intrinsic.
// If we don't have target data around, an unknown size in Location means
// that we should use the size of the pointee type. This isn't valid for
// init.trampoline, which writes more than an i8.
- if (AA.getDataLayout() == 0) return AliasAnalysis::Location();
+ if (!DL) return AliasAnalysis::Location();
// FIXME: We don't know the size of the trampoline, so we can't really
// handle it here.
AliasAnalysis &AA,
int64_t &EarlierOff,
int64_t &LaterOff) {
+ const DataLayout *DL = AA.getDataLayout();
const Value *P1 = Earlier.Ptr->stripPointerCasts();
const Value *P2 = Later.Ptr->stripPointerCasts();
// If we have no DataLayout information around, then the size of the store
// is inferrable from the pointee type. If they are the same type, then
// we know that the store is safe.
- if (AA.getDataLayout() == 0 &&
- Later.Ptr->getType() == Earlier.Ptr->getType())
+ if (DL == nullptr && Later.Ptr->getType() == Earlier.Ptr->getType())
return OverwriteComplete;
return OverwriteUnknown;
// Otherwise, we have to have size information, and the later store has to be
// larger than the earlier one.
if (Later.Size == AliasAnalysis::UnknownSize ||
- Earlier.Size == AliasAnalysis::UnknownSize ||
- AA.getDataLayout() == 0)
+ Earlier.Size == AliasAnalysis::UnknownSize || DL == nullptr)
return OverwriteUnknown;
// Check to see if the later store is to the entire object (either a global,
- // an alloca, or a byval argument). If so, then it clearly overwrites any
- // other store to the same object.
- const DataLayout *TD = AA.getDataLayout();
-
- const Value *UO1 = GetUnderlyingObject(P1, TD),
- *UO2 = GetUnderlyingObject(P2, TD);
+ // an alloca, or a byval/inalloca argument). If so, then it clearly
+ // overwrites any other store to the same object.
+ const Value *UO1 = GetUnderlyingObject(P1, DL),
+ *UO2 = GetUnderlyingObject(P2, DL);
// If we can't resolve the same pointers to the same object, then we can't
// analyze them at all.
// pointers are equal, then we can reason about the two stores.
EarlierOff = 0;
LaterOff = 0;
- const Value *BP1 = GetPointerBaseWithConstantOffset(P1, EarlierOff, TD);
- const Value *BP2 = GetPointerBaseWithConstantOffset(P2, LaterOff, TD);
+ const Value *BP1 = GetPointerBaseWithConstantOffset(P1, EarlierOff, DL);
+ const Value *BP2 = GetPointerBaseWithConstantOffset(P2, LaterOff, DL);
// If the base pointers still differ, we have two completely different stores.
if (BP1 != BP2)
// Self reads can only happen for instructions that read memory. Get the
// location read.
AliasAnalysis::Location InstReadLoc = getLocForRead(Inst, AA);
- if (InstReadLoc.Ptr == 0) return false; // Not a reading instruction.
+ if (!InstReadLoc.Ptr) return false; // Not a reading instruction.
// If the read and written loc obviously don't alias, it isn't a read.
if (AA.isNoAlias(InstReadLoc, InstStoreLoc)) return false;
DeleteDeadInstruction(SI, *MD, TLI);
- if (NextInst == 0) // Next instruction deleted.
+ if (!NextInst) // Next instruction deleted.
BBI = BB.begin();
else if (BBI != BB.begin()) // Revisit this instruction if possible.
--BBI;
AliasAnalysis::Location Loc = getLocForWrite(Inst, *AA);
// If we didn't get a useful location, fail.
- if (Loc.Ptr == 0)
+ if (!Loc.Ptr)
continue;
while (InstDep.isDef() || InstDep.isClobber()) {
Instruction *DepWrite = InstDep.getInst();
AliasAnalysis::Location DepLoc = getLocForWrite(DepWrite, *AA);
// If we didn't get a useful location, or if it isn't a size, bail out.
- if (DepLoc.Ptr == 0)
+ if (!DepLoc.Ptr)
break;
// If we find a write that is a) removable (i.e., non-volatile), b) is
if (!AA->isMustAlias(F->getArgOperand(0), DepPointer))
break;
- Instruction *Next = llvm::next(BasicBlock::iterator(Dependency));
+ Instruction *Next = std::next(BasicBlock::iterator(Dependency));
// DCE instructions only used to calculate that store
DeleteDeadInstruction(Dependency, *MD, TLI);
return MadeChange;
}
-namespace {
- struct CouldRef {
- typedef Value *argument_type;
- const CallSite CS;
- AliasAnalysis *AA;
-
- bool operator()(Value *I) {
- // See if the call site touches the value.
- AliasAnalysis::ModRefResult A =
- AA->getModRefInfo(CS, I, getPointerSize(I, *AA));
-
- return A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref;
- }
- };
-}
-
/// handleEndBlock - Remove dead stores to stack-allocated locations in the
/// function end block. Ex:
/// %A = alloca i32
DeadStackObjects.insert(I);
}
- // Treat byval arguments the same, stores to them are dead at the end of the
- // function.
+ // Treat byval or inalloca arguments the same, stores to them are dead at the
+ // end of the function.
for (Function::arg_iterator AI = BB.getParent()->arg_begin(),
AE = BB.getParent()->arg_end(); AI != AE; ++AI)
- if (AI->hasByValAttr())
+ if (AI->hasByValOrInAllocaAttr())
DeadStackObjects.insert(AI);
// Scan the basic block backwards
for (SmallVectorImpl<Value *>::iterator I = Pointers.begin(),
E = Pointers.end(); I != E; ++I) {
dbgs() << **I;
- if (llvm::next(I) != E)
+ if (std::next(I) != E)
dbgs() << ", ";
}
dbgs() << '\n');
// If the call might load from any of our allocas, then any store above
// the call is live.
- CouldRef Pred = { CS, AA };
- DeadStackObjects.remove_if(Pred);
+ DeadStackObjects.remove_if([&](Value *I) {
+ // See if the call site touches the value.
+ AliasAnalysis::ModRefResult A =
+ AA->getModRefInfo(CS, I, getPointerSize(I, *AA));
+
+ return A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref;
+ });
// If all of the allocas were clobbered by the call then we're not going
// to find anything else to process.
return MadeChange;
}
-namespace {
- struct CouldAlias {
- typedef Value *argument_type;
- const AliasAnalysis::Location &LoadedLoc;
- AliasAnalysis *AA;
-
- bool operator()(Value *I) {
- // See if the loaded location could alias the stack location.
- AliasAnalysis::Location StackLoc(I, getPointerSize(I, *AA));
- return !AA->isNoAlias(StackLoc, LoadedLoc);
- }
- };
-}
-
/// RemoveAccessedObjects - Check to see if the specified location may alias any
/// of the stack objects in the DeadStackObjects set. If so, they become live
/// because the location is being loaded.
}
// Remove objects that could alias LoadedLoc.
- CouldAlias Pred = { LoadedLoc, AA };
- DeadStackObjects.remove_if(Pred);
+ DeadStackObjects.remove_if([&](Value *I) {
+ // See if the loaded location could alias the stack location.
+ AliasAnalysis::Location StackLoc(I, getPointerSize(I, *AA));
+ return !AA->isNoAlias(StackLoc, LoadedLoc);
+ });
}
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