//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "early-cse"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/ScopedHashTable.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AssumptionTracker.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/PatternMatch.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/RecyclingAllocator.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Transforms/Utils/Local.h"
-#include <vector>
+#include <deque>
using namespace llvm;
+using namespace llvm::PatternMatch;
+
+#define DEBUG_TYPE "early-cse"
STATISTIC(NumSimplify, "Number of instructions simplified or DCE'd");
STATISTIC(NumCSE, "Number of instructions CSE'd");
return false;
CallInst *CI = dyn_cast<CallInst>(Inst);
- if (CI == 0 || !CI->onlyReadsMemory())
+ if (!CI || !CI->onlyReadsMemory())
return false;
return true;
}
/// cases.
class EarlyCSE : public FunctionPass {
public:
- const DataLayout *TD;
+ const DataLayout *DL;
const TargetLibraryInfo *TLI;
DominatorTree *DT;
+ AssumptionTracker *AT;
typedef RecyclingAllocator<BumpPtrAllocator,
ScopedHashTableVal<SimpleValue, Value*> > AllocatorTy;
typedef ScopedHashTable<SimpleValue, Value*, DenseMapInfo<SimpleValue>,
initializeEarlyCSEPass(*PassRegistry::getPassRegistry());
}
- bool runOnFunction(Function &F);
+ bool runOnFunction(Function &F) override;
private:
bool processNode(DomTreeNode *Node);
// This transformation requires dominator postdominator info
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<AssumptionTracker>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfo>();
AU.setPreservesCFG();
}
INITIALIZE_PASS_BEGIN(EarlyCSE, "early-cse", "Early CSE", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionTracker)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
INITIALIZE_PASS_END(EarlyCSE, "early-cse", "Early CSE", false, false)
// have invalidated the live-out memory values of our parent value. For now,
// just be conservative and invalidate memory if this block has multiple
// predecessors.
- if (BB->getSinglePredecessor() == 0)
+ if (!BB->getSinglePredecessor())
++CurrentGeneration;
/// LastStore - Keep track of the last non-volatile store that we saw... for
/// as long as there in no instruction that reads memory. If we see a store
/// to the same location, we delete the dead store. This zaps trivial dead
/// stores which can occur in bitfield code among other things.
- StoreInst *LastStore = 0;
+ StoreInst *LastStore = nullptr;
bool Changed = false;
continue;
}
+ // Skip assume intrinsics, they don't really have side effects (although
+ // they're marked as such to ensure preservation of control dependencies),
+ // and this pass will not disturb any of the assumption's control
+ // dependencies.
+ if (match(Inst, m_Intrinsic<Intrinsic::assume>())) {
+ DEBUG(dbgs() << "EarlyCSE skipping assumption: " << *Inst << '\n');
+ continue;
+ }
+
// If the instruction can be simplified (e.g. X+0 = X) then replace it with
// its simpler value.
- if (Value *V = SimplifyInstruction(Inst, TD, TLI, DT)) {
+ if (Value *V = SimplifyInstruction(Inst, DL, TLI, DT, AT)) {
DEBUG(dbgs() << "EarlyCSE Simplify: " << *Inst << " to: " << *V << '\n');
Inst->replaceAllUsesWith(V);
Inst->eraseFromParent();
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
// Ignore volatile loads.
if (!LI->isSimple()) {
- LastStore = 0;
+ LastStore = nullptr;
continue;
}
// generation, replace this instruction.
std::pair<Value*, unsigned> InVal =
AvailableLoads->lookup(Inst->getOperand(0));
- if (InVal.first != 0 && InVal.second == CurrentGeneration) {
+ if (InVal.first != nullptr && InVal.second == CurrentGeneration) {
DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst << " to: "
<< *InVal.first << '\n');
if (!Inst->use_empty()) Inst->replaceAllUsesWith(InVal.first);
// Otherwise, remember that we have this instruction.
AvailableLoads->insert(Inst->getOperand(0),
std::pair<Value*, unsigned>(Inst, CurrentGeneration));
- LastStore = 0;
+ LastStore = nullptr;
continue;
}
// If this instruction may read from memory, forget LastStore.
if (Inst->mayReadFromMemory())
- LastStore = 0;
+ LastStore = nullptr;
// If this is a read-only call, process it.
if (CallValue::canHandle(Inst)) {
// If we have an available version of this call, and if it is the right
// generation, replace this instruction.
std::pair<Value*, unsigned> InVal = AvailableCalls->lookup(Inst);
- if (InVal.first != 0 && InVal.second == CurrentGeneration) {
+ if (InVal.first != nullptr && InVal.second == CurrentGeneration) {
DEBUG(dbgs() << "EarlyCSE CSE CALL: " << *Inst << " to: "
<< *InVal.first << '\n');
if (!Inst->use_empty()) Inst->replaceAllUsesWith(InVal.first);
LastStore->eraseFromParent();
Changed = true;
++NumDSE;
- LastStore = 0;
- continue;
+ LastStore = nullptr;
+ // fallthrough - we can exploit information about this store
}
// Okay, we just invalidated anything we knew about loaded values. Try
bool EarlyCSE::runOnFunction(Function &F) {
- std::vector<StackNode *> nodesToProcess;
+ if (skipOptnoneFunction(F))
+ return false;
+
+ // Note, deque is being used here because there is significant performance gains
+ // over vector when the container becomes very large due to the specific access
+ // patterns. For more information see the mailing list discussion on this:
+ // http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120116/135228.html
+ std::deque<StackNode *> nodesToProcess;
- TD = getAnalysisIfAvailable<DataLayout>();
+ DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+ DL = DLP ? &DLP->getDataLayout() : nullptr;
TLI = &getAnalysis<TargetLibraryInfo>();
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ AT = &getAnalysis<AssumptionTracker>();
// Tables that the pass uses when walking the domtree.
ScopedHTType AVTable;
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