//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "iv-users"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/IVUsers.h"
-#include "llvm/Constants.h"
-#include "llvm/Instructions.h"
-#include "llvm/Type.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Type.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
using namespace llvm;
+#define DEBUG_TYPE "iv-users"
+
char IVUsers::ID = 0;
INITIALIZE_PASS_BEGIN(IVUsers, "iv-users",
"Induction Variable Users", false, true)
-INITIALIZE_PASS_DEPENDENCY(LoopInfo)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
-INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
INITIALIZE_PASS_END(IVUsers, "iv-users",
"Induction Variable Users", false, true)
/// form.
static bool isSimplifiedLoopNest(BasicBlock *BB, const DominatorTree *DT,
const LoopInfo *LI,
- SmallPtrSet<Loop*,16> &SimpleLoopNests) {
- Loop *NearestLoop = 0;
+ SmallPtrSetImpl<Loop*> &SimpleLoopNests) {
+ Loop *NearestLoop = nullptr;
for (DomTreeNode *Rung = DT->getNode(BB);
Rung; Rung = Rung->getIDom()) {
BasicBlock *DomBB = Rung->getBlock();
return true;
}
-/// AddUsersIfInteresting - Inspect the specified instruction. If it is a
+/// AddUsersImpl - Inspect the specified instruction. If it is a
/// reducible SCEV, recursively add its users to the IVUsesByStride set and
/// return true. Otherwise, return false.
-bool IVUsers::AddUsersIfInteresting(Instruction *I,
- SmallPtrSet<Loop*,16> &SimpleLoopNests) {
+bool IVUsers::AddUsersImpl(Instruction *I,
+ SmallPtrSetImpl<Loop*> &SimpleLoopNests) {
+ const DataLayout &DL = I->getModule()->getDataLayout();
+
// Add this IV user to the Processed set before returning false to ensure that
// all IV users are members of the set. See IVUsers::isIVUserOrOperand.
- if (!Processed.insert(I))
+ if (!Processed.insert(I).second)
return true; // Instruction already handled.
if (!SE->isSCEVable(I->getType()))
return false; // Void and FP expressions cannot be reduced.
+ // IVUsers is used by LSR which assumes that all SCEV expressions are safe to
+ // pass to SCEVExpander. Expressions are not safe to expand if they represent
+ // operations that are not safe to speculate, namely integer division.
+ if (!isa<PHINode>(I) && !isSafeToSpeculativelyExecute(I))
+ return false;
+
// LSR is not APInt clean, do not touch integers bigger than 64-bits.
// Also avoid creating IVs of non-native types. For example, we don't want a
// 64-bit IV in 32-bit code just because the loop has one 64-bit cast.
uint64_t Width = SE->getTypeSizeInBits(I->getType());
- if (Width > 64 || (TD && !TD->isLegalInteger(Width)))
+ if (Width > 64 || !DL.isLegalInteger(Width))
+ return false;
+
+ // Don't attempt to promote ephemeral values to indvars. They will be removed
+ // later anyway.
+ if (EphValues.count(I))
return false;
// Get the symbolic expression for this instruction.
return false;
SmallPtrSet<Instruction *, 4> UniqueUsers;
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- if (!UniqueUsers.insert(User))
+ for (Use &U : I->uses()) {
+ Instruction *User = cast<Instruction>(U.getUser());
+ if (!UniqueUsers.insert(User).second)
continue;
// Do not infinitely recurse on PHI nodes.
BasicBlock *UseBB = User->getParent();
// A phi's use is live out of its predecessor block.
if (PHINode *PHI = dyn_cast<PHINode>(User)) {
- unsigned OperandNo = UI.getOperandNo();
+ unsigned OperandNo = U.getOperandNo();
unsigned ValNo = PHINode::getIncomingValueNumForOperand(OperandNo);
UseBB = PHI->getIncomingBlock(ValNo);
}
bool AddUserToIVUsers = false;
if (LI->getLoopFor(User->getParent()) != L) {
if (isa<PHINode>(User) || Processed.count(User) ||
- !AddUsersIfInteresting(User, SimpleLoopNests)) {
+ !AddUsersImpl(User, SimpleLoopNests)) {
DEBUG(dbgs() << "FOUND USER in other loop: " << *User << '\n'
<< " OF SCEV: " << *ISE << '\n');
AddUserToIVUsers = true;
}
- } else if (Processed.count(User)
- || !AddUsersIfInteresting(User, SimpleLoopNests)) {
+ } else if (Processed.count(User) || !AddUsersImpl(User, SimpleLoopNests)) {
DEBUG(dbgs() << "FOUND USER: " << *User << '\n'
<< " OF SCEV: " << *ISE << '\n');
AddUserToIVUsers = true;
if (AddUserToIVUsers) {
// Okay, we found a user that we cannot reduce.
- IVUses.push_back(new IVStrideUse(this, User, I));
- IVStrideUse &NewUse = IVUses.back();
+ IVStrideUse &NewUse = AddUser(User, I);
// Autodetect the post-inc loop set, populating NewUse.PostIncLoops.
// The regular return value here is discarded; instead of recording
// it, we just recompute it when we need it.
+ const SCEV *OriginalISE = ISE;
ISE = TransformForPostIncUse(NormalizeAutodetect,
ISE, User, I,
NewUse.PostIncLoops,
*SE, *DT);
+
+ // PostIncNormalization effectively simplifies the expression under
+ // pre-increment assumptions. Those assumptions (no wrapping) might not
+ // hold for the post-inc value. Catch such cases by making sure the
+ // transformation is invertible.
+ if (OriginalISE != ISE) {
+ const SCEV *DenormalizedISE =
+ TransformForPostIncUse(Denormalize, ISE, User, I,
+ NewUse.PostIncLoops, *SE, *DT);
+
+ // If we normalized the expression, but denormalization doesn't give the
+ // original one, discard this user.
+ if (OriginalISE != DenormalizedISE) {
+ DEBUG(dbgs() << " DISCARDING (NORMALIZATION ISN'T INVERTIBLE): "
+ << *ISE << '\n');
+ IVUses.pop_back();
+ return false;
+ }
+ }
DEBUG(if (SE->getSCEV(I) != ISE)
dbgs() << " NORMALIZED TO: " << *ISE << '\n');
}
return true;
}
+bool IVUsers::AddUsersIfInteresting(Instruction *I) {
+ // SCEVExpander can only handle users that are dominated by simplified loop
+ // entries. Keep track of all loops that are only dominated by other simple
+ // loops so we don't traverse the domtree for each user.
+ SmallPtrSet<Loop*,16> SimpleLoopNests;
+
+ return AddUsersImpl(I, SimpleLoopNests);
+}
+
IVStrideUse &IVUsers::AddUser(Instruction *User, Value *Operand) {
IVUses.push_back(new IVStrideUse(this, User, Operand));
return IVUses.back();
}
void IVUsers::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<LoopInfo>();
- AU.addRequired<DominatorTree>();
- AU.addRequired<ScalarEvolution>();
+ AU.addRequired<AssumptionCacheTracker>();
+ AU.addRequired<LoopInfoWrapperPass>();
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addRequired<ScalarEvolutionWrapperPass>();
AU.setPreservesAll();
}
bool IVUsers::runOnLoop(Loop *l, LPPassManager &LPM) {
L = l;
- LI = &getAnalysis<LoopInfo>();
- DT = &getAnalysis<DominatorTree>();
- SE = &getAnalysis<ScalarEvolution>();
- TD = getAnalysisIfAvailable<TargetData>();
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(
+ *L->getHeader()->getParent());
+ LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
- // SCEVExpander can only handle users that are dominated by simplified loop
- // entries. Keep track of all loops that are only dominated by other simple
- // loops so we don't traverse the domtree for each user.
- SmallPtrSet<Loop*,16> SimpleLoopNests;
+ // Collect ephemeral values so that AddUsersIfInteresting skips them.
+ EphValues.clear();
+ CodeMetrics::collectEphemeralValues(L, AC, EphValues);
// Find all uses of induction variables in this loop, and categorize
// them by stride. Start by finding all of the PHI nodes in the header for
// this loop. If they are induction variables, inspect their uses.
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I)
- (void)AddUsersIfInteresting(I, SimpleLoopNests);
+ (void)AddUsersIfInteresting(&*I);
return false;
}
void IVUsers::print(raw_ostream &OS, const Module *M) const {
OS << "IV Users for loop ";
- WriteAsOperand(OS, L->getHeader(), false);
+ L->getHeader()->printAsOperand(OS, false);
if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
OS << " with backedge-taken count "
<< *SE->getBackedgeTakenCount(L);
for (ilist<IVStrideUse>::const_iterator UI = IVUses.begin(),
E = IVUses.end(); UI != E; ++UI) {
OS << " ";
- WriteAsOperand(OS, UI->getOperandValToReplace(), false);
+ UI->getOperandValToReplace()->printAsOperand(OS, false);
OS << " = " << *getReplacementExpr(*UI);
for (PostIncLoopSet::const_iterator
I = UI->PostIncLoops.begin(),
E = UI->PostIncLoops.end(); I != E; ++I) {
OS << " (post-inc with loop ";
- WriteAsOperand(OS, (*I)->getHeader(), false);
+ (*I)->getHeader()->printAsOperand(OS, false);
OS << ")";
}
OS << " in ";
- UI->getUser()->print(OS);
+ if (UI->getUser())
+ UI->getUser()->print(OS);
+ else
+ OS << "Printing <null> User";
OS << '\n';
}
}
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void IVUsers::dump() const {
print(dbgs());
}
+#endif
void IVUsers::releaseMemory() {
Processed.clear();
I != E; ++I)
if (const SCEVAddRecExpr *AR = findAddRecForLoop(*I, L))
return AR;
- return 0;
+ return nullptr;
}
- return 0;
+ return nullptr;
}
const SCEV *IVUsers::getStride(const IVStrideUse &IU, const Loop *L) const {
if (const SCEVAddRecExpr *AR = findAddRecForLoop(getExpr(IU), L))
return AR->getStepRecurrence(*SE);
- return 0;
+ return nullptr;
}
void IVStrideUse::transformToPostInc(const Loop *L) {
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