//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/LLVMContext.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Target/TargetLowering.h"
-#include "llvm/ADT/STLExtras.h"
using namespace llvm;
Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
Instruction::CastOps Op,
BasicBlock::iterator IP) {
+ // This function must be called with the builder having a valid insertion
+ // point. It doesn't need to be the actual IP where the uses of the returned
+ // cast will be added, but it must dominate such IP.
+ // We use this precondition to produce a cast that will dominate all its
+ // uses. In particular, this is crucial for the case where the builder's
+ // insertion point *is* the point where we were asked to put the cast.
+ // Since we don't know the builder's insertion point is actually
+ // where the uses will be added (only that it dominates it), we are
+ // not allowed to move it.
+ BasicBlock::iterator BIP = Builder.GetInsertPoint();
+
+ Instruction *Ret = NULL;
+
// Check to see if there is already a cast!
for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
if (U->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(U))
if (CI->getOpcode() == Op) {
- // If the cast isn't where we want it, fix it.
- if (BasicBlock::iterator(CI) != IP) {
+ // If the cast isn't where we want it, create a new cast at IP.
+ // Likewise, do not reuse a cast at BIP because it must dominate
+ // instructions that might be inserted before BIP.
+ if (BasicBlock::iterator(CI) != IP || BIP == IP) {
// Create a new cast, and leave the old cast in place in case
// it is being used as an insert point. Clear its operand
// so that it doesn't hold anything live.
- Instruction *NewCI = CastInst::Create(Op, V, Ty, "", IP);
- NewCI->takeName(CI);
- CI->replaceAllUsesWith(NewCI);
+ Ret = CastInst::Create(Op, V, Ty, "", IP);
+ Ret->takeName(CI);
+ CI->replaceAllUsesWith(Ret);
CI->setOperand(0, UndefValue::get(V->getType()));
- rememberInstruction(NewCI);
- return NewCI;
+ break;
}
- rememberInstruction(CI);
- return CI;
+ Ret = CI;
+ break;
}
}
// Create a new cast.
- Instruction *I = CastInst::Create(Op, V, Ty, V->getName(), IP);
- rememberInstruction(I);
- return I;
+ if (!Ret)
+ Ret = CastInst::Create(Op, V, Ty, V->getName(), IP);
+
+ // We assert at the end of the function since IP might point to an
+ // instruction with different dominance properties than a cast
+ // (an invoke for example) and not dominate BIP (but the cast does).
+ assert(SE.DT->dominates(Ret, BIP));
+
+ rememberInstruction(Ret);
+ return Ret;
}
/// InsertNoopCastOfTo - Insert a cast of V to the specified type,
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
- while (isa<PHINode>(IP) || isa<DbgInfoIntrinsic>(IP) ||
- isa<LandingPadInst>(IP))
+ while (isa<PHINode>(IP) || isa<LandingPadInst>(IP))
++IP;
return ReuseOrCreateCast(I, Ty, Op, IP);
}
}
// Save the original insertion point so we can restore it when we're done.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
+ BuilderType::InsertPointGuard Guard(Builder);
// Move the insertion point out of as many loops as we can.
while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
// If we haven't found this binop, insert it.
Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
- BO->setDebugLoc(SaveInsertPt->getDebugLoc());
+ BO->setDebugLoc(Loc);
rememberInstruction(BO);
- // Restore the original insert point.
- if (SaveInsertBB)
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
-
return BO;
}
const SCEV *&Remainder,
const SCEV *Factor,
ScalarEvolution &SE,
- const TargetData *TD) {
+ const DataLayout *TD) {
// Everything is divisible by one.
if (Factor->isOne())
return true;
// of the given factor.
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
if (TD) {
- // With TargetData, the size is known. Check if there is a constant
+ // With DataLayout, the size is known. Check if there is a constant
// operand which is a multiple of the given factor. If so, we can
// factor it.
const SCEVConstant *FC = cast<SCEVConstant>(Factor);
return true;
}
} else {
- // Without TargetData, check if Factor can be factored out of any of the
+ // Without DataLayout, check if Factor can be factored out of any of the
// Mul's operands. If so, we can just remove it.
for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
const SCEV *SOp = M->getOperand(i);
const SCEV *Start = A->getStart();
if (!FactorOutConstant(Start, Remainder, Factor, SE, TD))
return false;
- // FIXME: can use A->getNoWrapFlags(FlagNW)
- S = SE.getAddRecExpr(Start, Step, A->getLoop(), SCEV::FlagAnyWrap);
+ S = SE.getAddRecExpr(Start, Step, A->getLoop(),
+ A->getNoWrapFlags(SCEV::FlagNW));
return true;
}
AddRecs.push_back(SE.getAddRecExpr(Zero,
A->getStepRecurrence(SE),
A->getLoop(),
- // FIXME: A->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ A->getNoWrapFlags(SCEV::FlagNW)));
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
Ops[i] = Zero;
Ops.append(Add->op_begin(), Add->op_end());
// without the other.
SplitAddRecs(Ops, Ty, SE);
+ Type *IntPtrTy = SE.TD
+ ? SE.TD->getIntPtrType(PTy)
+ : Type::getInt64Ty(PTy->getContext());
+
// Descend down the pointer's type and attempt to convert the other
// operands into GEP indices, at each level. The first index in a GEP
// indexes into the array implied by the pointer operand; the rest of
// array indexing.
SmallVector<const SCEV *, 8> ScaledOps;
if (ElTy->isSized()) {
- const SCEV *ElSize = SE.getSizeOfExpr(ElTy);
+ const SCEV *ElSize = SE.getSizeOfExpr(IntPtrTy, ElTy);
if (!ElSize->isZero()) {
SmallVector<const SCEV *, 8> NewOps;
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
// An empty struct has no fields.
if (STy->getNumElements() == 0) break;
if (SE.TD) {
- // With TargetData, field offsets are known. See if a constant offset
+ // With DataLayout, field offsets are known. See if a constant offset
// falls within any of the struct fields.
if (Ops.empty()) break;
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
}
}
} else {
- // Without TargetData, just check for an offsetof expression of the
+ // Without DataLayout, just check for an offsetof expression of the
// appropriate struct type.
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Ops[i])) {
V = InsertNoopCastOfTo(V,
Type::getInt8PtrTy(Ty->getContext(), PTy->getAddressSpace()));
+ assert(!isa<Instruction>(V) ||
+ SE.DT->dominates(cast<Instruction>(V), Builder.GetInsertPoint()));
+
// Expand the operands for a plain byte offset.
Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
}
// Save the original insertion point so we can restore it when we're done.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPointGuard Guard(Builder);
// Move the insertion point out of as many loops as we can.
while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
Value *GEP = Builder.CreateGEP(V, Idx, "uglygep");
rememberInstruction(GEP);
- // Restore the original insert point.
- if (SaveInsertBB)
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
-
return GEP;
}
// Save the original insertion point so we can restore it when we're done.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPoint SaveInsertPt = Builder.saveIP();
// Move the insertion point out of as many loops as we can.
while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
rememberInstruction(GEP);
// Restore the original insert point.
- if (SaveInsertBB)
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+ Builder.restoreIP(SaveInsertPt);
return expand(SE.getAddExpr(Ops));
}
return RelevantLoops[D] = Result;
}
llvm_unreachable("Unexpected SCEV type!");
- return 0;
}
namespace {
SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
A->getStepRecurrence(SE),
A->getLoop(),
- // FIXME: A->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ A->getNoWrapFlags(SCEV::FlagNW)));
}
if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
Base = A->getOperand(A->getNumOperands()-1);
return isNormalAddRecExprPHI(PN, IncV, L);
}
-/// Determine if this cyclic phi is in a form that would have been generated by
-/// LSR. We don't care if the phi was actually expanded in this pass, as long
-/// as it is in a low-cost form, for example, no implied multiplication. This
-/// should match any patterns generated by getAddRecExprPHILiterally and
-/// expandAddtoGEP.
-bool SCEVExpander::isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV,
- const Loop *L) {
+/// getIVIncOperand returns an induction variable increment's induction
+/// variable operand.
+///
+/// If allowScale is set, any type of GEP is allowed as long as the nonIV
+/// operands dominate InsertPos.
+///
+/// If allowScale is not set, ensure that a GEP increment conforms to one of the
+/// simple patterns generated by getAddRecExprPHILiterally and
+/// expandAddtoGEP. If the pattern isn't recognized, return NULL.
+Instruction *SCEVExpander::getIVIncOperand(Instruction *IncV,
+ Instruction *InsertPos,
+ bool allowScale) {
+ if (IncV == InsertPos)
+ return NULL;
+
switch (IncV->getOpcode()) {
+ default:
+ return NULL;
// Check for a simple Add/Sub or GEP of a loop invariant step.
case Instruction::Add:
- case Instruction::Sub:
- return IncV->getOperand(0) == PN
- && L->isLoopInvariant(IncV->getOperand(1));
+ case Instruction::Sub: {
+ Instruction *OInst = dyn_cast<Instruction>(IncV->getOperand(1));
+ if (!OInst || SE.DT->dominates(OInst, InsertPos))
+ return dyn_cast<Instruction>(IncV->getOperand(0));
+ return NULL;
+ }
case Instruction::BitCast:
- IncV = dyn_cast<GetElementPtrInst>(IncV->getOperand(0));
- if (!IncV)
- return false;
- // fall-thru to GEP handling
- case Instruction::GetElementPtr: {
- // This must be a pointer addition of constants (pretty) or some number of
- // address-size elements (ugly).
+ return dyn_cast<Instruction>(IncV->getOperand(0));
+ case Instruction::GetElementPtr:
for (Instruction::op_iterator I = IncV->op_begin()+1, E = IncV->op_end();
I != E; ++I) {
if (isa<Constant>(*I))
continue;
- // ugly geps have 2 operands.
- // i1* is used by the expander to represent an address-size element.
+ if (Instruction *OInst = dyn_cast<Instruction>(*I)) {
+ if (!SE.DT->dominates(OInst, InsertPos))
+ return NULL;
+ }
+ if (allowScale) {
+ // allow any kind of GEP as long as it can be hoisted.
+ continue;
+ }
+ // This must be a pointer addition of constants (pretty), which is already
+ // handled, or some number of address-size elements (ugly). Ugly geps
+ // have 2 operands. i1* is used by the expander to represent an
+ // address-size element.
if (IncV->getNumOperands() != 2)
- return false;
+ return NULL;
unsigned AS = cast<PointerType>(IncV->getType())->getAddressSpace();
if (IncV->getType() != Type::getInt1PtrTy(SE.getContext(), AS)
&& IncV->getType() != Type::getInt8PtrTy(SE.getContext(), AS))
- return false;
- // Ensure the operands dominate the insertion point. I don't know of a
- // case when this would not be true, so this is somewhat untested.
- if (L == IVIncInsertLoop) {
- for (User::op_iterator OI = IncV->op_begin()+1,
- OE = IncV->op_end(); OI != OE; ++OI)
- if (Instruction *OInst = dyn_cast<Instruction>(OI))
- if (!SE.DT->dominates(OInst, IVIncInsertPos))
- return false;
- }
+ return NULL;
break;
}
- IncV = dyn_cast<Instruction>(IncV->getOperand(0));
- if (IncV && IncV->getOpcode() == Instruction::BitCast)
- IncV = dyn_cast<Instruction>(IncV->getOperand(0));
- return IncV == PN;
+ return dyn_cast<Instruction>(IncV->getOperand(0));
}
- default:
+}
+
+/// hoistStep - Attempt to hoist a simple IV increment above InsertPos to make
+/// it available to other uses in this loop. Recursively hoist any operands,
+/// until we reach a value that dominates InsertPos.
+bool SCEVExpander::hoistIVInc(Instruction *IncV, Instruction *InsertPos) {
+ if (SE.DT->dominates(IncV, InsertPos))
+ return true;
+
+ // InsertPos must itself dominate IncV so that IncV's new position satisfies
+ // its existing users.
+ if (isa<PHINode>(InsertPos)
+ || !SE.DT->dominates(InsertPos->getParent(), IncV->getParent()))
return false;
+
+ // Check that the chain of IV operands leading back to Phi can be hoisted.
+ SmallVector<Instruction*, 4> IVIncs;
+ for(;;) {
+ Instruction *Oper = getIVIncOperand(IncV, InsertPos, /*allowScale*/true);
+ if (!Oper)
+ return false;
+ // IncV is safe to hoist.
+ IVIncs.push_back(IncV);
+ IncV = Oper;
+ if (SE.DT->dominates(IncV, InsertPos))
+ break;
+ }
+ for (SmallVectorImpl<Instruction*>::reverse_iterator I = IVIncs.rbegin(),
+ E = IVIncs.rend(); I != E; ++I) {
+ (*I)->moveBefore(InsertPos);
}
+ return true;
+}
+
+/// Determine if this cyclic phi is in a form that would have been generated by
+/// LSR. We don't care if the phi was actually expanded in this pass, as long
+/// as it is in a low-cost form, for example, no implied multiplication. This
+/// should match any patterns generated by getAddRecExprPHILiterally and
+/// expandAddtoGEP.
+bool SCEVExpander::isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV,
+ const Loop *L) {
+ for(Instruction *IVOper = IncV;
+ (IVOper = getIVIncOperand(IVOper, L->getLoopPreheader()->getTerminator(),
+ /*allowScale=*/false));) {
+ if (IVOper == PN)
+ return true;
+ }
+ return false;
}
/// expandIVInc - Expand an IV increment at Builder's current InsertPos.
if (LSRMode) {
if (!isExpandedAddRecExprPHI(PN, IncV, L))
continue;
+ if (L == IVIncInsertLoop && !hoistIVInc(IncV, IVIncInsertPos))
+ continue;
}
else {
if (!isNormalAddRecExprPHI(PN, IncV, L))
continue;
+ if (L == IVIncInsertLoop)
+ do {
+ if (SE.DT->dominates(IncV, IVIncInsertPos))
+ break;
+ // Make sure the increment is where we want it. But don't move it
+ // down past a potential existing post-inc user.
+ IncV->moveBefore(IVIncInsertPos);
+ IVIncInsertPos = IncV;
+ IncV = cast<Instruction>(IncV->getOperand(0));
+ } while (IncV != PN);
}
// Ok, the add recurrence looks usable.
// Remember this PHI, even in post-inc mode.
InsertedValues.insert(PN);
// Remember the increment.
rememberInstruction(IncV);
- if (L == IVIncInsertLoop)
- do {
- if (SE.DT->dominates(IncV, IVIncInsertPos))
- break;
- // Make sure the increment is where we want it. But don't move it
- // down past a potential existing post-inc user.
- IncV->moveBefore(IVIncInsertPos);
- IVIncInsertPos = IncV;
- IncV = cast<Instruction>(IncV->getOperand(0));
- } while (IncV != PN);
return PN;
}
}
// Save the original insertion point so we can restore it when we're done.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPointGuard Guard(Builder);
// Another AddRec may need to be recursively expanded below. For example, if
// this AddRec is quadratic, the StepV may itself be an AddRec in this
IVIncInsertPos : Pred->getTerminator();
Builder.SetInsertPoint(InsertPos);
Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
-
+ if (isa<OverflowingBinaryOperator>(IncV)) {
+ if (Normalized->getNoWrapFlags(SCEV::FlagNUW))
+ cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
+ if (Normalized->getNoWrapFlags(SCEV::FlagNSW))
+ cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
+ }
PN->addIncoming(IncV, Pred);
}
- // Restore the original insert point.
- if (SaveInsertBB)
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
-
// After expanding subexpressions, restore the PostIncLoops set so the caller
// can ensure that IVIncrement dominates the current uses.
PostIncLoops = SavedPostIncLoops;
Normalized = cast<SCEVAddRecExpr>(
SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
Normalized->getLoop(),
- // FIXME: Normalized->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ Normalized->getNoWrapFlags(SCEV::FlagNW)));
}
// Strip off any non-loop-dominating component from the addrec step.
PostLoopScale = Step;
Step = SE.getConstant(Normalized->getType(), 1);
Normalized =
- cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start, Step,
- Normalized->getLoop(),
- // FIXME: Normalized
- // ->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
+ cast<SCEVAddRecExpr>(SE.getAddRecExpr(
+ Start, Step, Normalized->getLoop(),
+ Normalized->getNoWrapFlags(SCEV::FlagNW)));
}
// Expand the core addrec. If we need post-loop scaling, force it to
!ExpandTy->isPointerTy() && Step->isNonConstantNegative();
if (useSubtract)
Step = SE.getNegativeSCEV(Step);
- // Expand the step somewhere that dominates the loop header.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
- Value *StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin());
- // Restore the insertion point to the place where the caller has
- // determined dominates all uses.
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
+ Value *StepV;
+ {
+ // Expand the step somewhere that dominates the loop header.
+ BuilderType::InsertPointGuard Guard(Builder);
+ StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin());
+ }
Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
}
}
// Re-apply any non-loop-dominating scale.
if (PostLoopScale) {
+ assert(S->isAffine() && "Can't linearly scale non-affine recurrences.");
Result = InsertNoopCastOfTo(Result, IntTy);
Result = Builder.CreateMul(Result,
expandCodeFor(PostLoopScale, IntTy));
for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
- // FIXME: S->getNoWrapFlags(FlagNW)
- SCEV::FlagAnyWrap));
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ S->getNoWrapFlags(SCEV::FlagNW)));
BasicBlock::iterator NewInsertPt =
llvm::next(BasicBlock::iterator(cast<Instruction>(V)));
+ BuilderType::InsertPointGuard Guard(Builder);
while (isa<PHINode>(NewInsertPt) || isa<DbgInfoIntrinsic>(NewInsertPt) ||
isa<LandingPadInst>(NewInsertPt))
++NewInsertPt;
V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0,
NewInsertPt);
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
if (!S->getStart()->isZero()) {
SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
NewOps[0] = SE.getConstant(Ty, 0);
- // FIXME: can use S->getNoWrapFlags()
- const SCEV *Rest = SE.getAddRecExpr(NewOps, L, SCEV::FlagAnyWrap);
+ const SCEV *Rest = SE.getAddRecExpr(NewOps, L,
+ S->getNoWrapFlags(SCEV::FlagNW));
// Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
// comments on expandAddToGEP for details.
Header->begin());
rememberInstruction(CanonicalIV);
+ SmallSet<BasicBlock *, 4> PredSeen;
Constant *One = ConstantInt::get(Ty, 1);
for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
BasicBlock *HP = *HPI;
+ if (!PredSeen.insert(HP))
+ continue;
+
if (L->contains(HP)) {
// Insert a unit add instruction right before the terminator
// corresponding to the back-edge.
}
Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty,
- Instruction *I) {
- BasicBlock::iterator IP = I;
- while (isInsertedInstruction(IP) || isa<DbgInfoIntrinsic>(IP))
- ++IP;
+ Instruction *IP) {
Builder.SetInsertPoint(IP->getParent(), IP);
return expandCodeFor(SH, Ty);
}
// there) so that it is guaranteed to dominate any user inside the loop.
if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
InsertPt = L->getHeader()->getFirstInsertionPt();
- while (isInsertedInstruction(InsertPt) || isa<DbgInfoIntrinsic>(InsertPt))
+ while (InsertPt != Builder.GetInsertPoint()
+ && (isInsertedInstruction(InsertPt)
+ || isa<DbgInfoIntrinsic>(InsertPt))) {
InsertPt = llvm::next(BasicBlock::iterator(InsertPt));
+ }
break;
}
// Check to see if we already expanded this here.
- std::map<std::pair<const SCEV *, Instruction *>,
- AssertingVH<Value> >::iterator I =
- InsertedExpressions.find(std::make_pair(S, InsertPt));
+ std::map<std::pair<const SCEV *, Instruction *>, TrackingVH<Value> >::iterator
+ I = InsertedExpressions.find(std::make_pair(S, InsertPt));
if (I != InsertedExpressions.end())
return I->second;
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPointGuard Guard(Builder);
Builder.SetInsertPoint(InsertPt->getParent(), InsertPt);
// Expand the expression into instructions.
//
// This is independent of PostIncLoops. The mapped value simply materializes
// the expression at this insertion point. If the mapped value happened to be
- // a postinc expansion, it could be reused by a non postinc user, but only if
+ // a postinc expansion, it could be reused by a non-postinc user, but only if
// its insertion point was already at the head of the loop.
InsertedExpressions[std::make_pair(S, InsertPt)] = V;
-
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
InsertedPostIncValues.insert(I);
else
InsertedValues.insert(I);
-
- // If we just claimed an existing instruction and that instruction had
- // been the insert point, adjust the insert point forward so that
- // subsequently inserted code will be dominated.
- if (Builder.GetInsertPoint() == I) {
- BasicBlock::iterator It = cast<Instruction>(I);
- do { ++It; } while (isInsertedInstruction(It) ||
- isa<DbgInfoIntrinsic>(It));
- Builder.SetInsertPoint(Builder.GetInsertBlock(), It);
- }
-}
-
-void SCEVExpander::restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I) {
- // If we acquired more instructions since the old insert point was saved,
- // advance past them.
- while (isInsertedInstruction(I) || isa<DbgInfoIntrinsic>(I)) ++I;
-
- Builder.SetInsertPoint(BB, I);
}
/// getOrInsertCanonicalInductionVariable - This method returns the
SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
// Emit code for it.
- BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
- BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+ BuilderType::InsertPointGuard Guard(Builder);
PHINode *V = cast<PHINode>(expandCodeFor(H, 0, L->getHeader()->begin()));
- if (SaveInsertBB)
- restoreInsertPoint(SaveInsertBB, SaveInsertPt);
return V;
}
-/// hoistStep - Attempt to hoist an IV increment above a potential use.
-///
-/// To successfully hoist, two criteria must be met:
-/// - IncV operands dominate InsertPos and
-/// - InsertPos dominates IncV
-///
-/// Meeting the second condition means that we don't need to check all of IncV's
-/// existing uses (it's moving up in the domtree).
-///
-/// This does not yet recursively hoist the operands, although that would
-/// not be difficult.
-///
-/// This does not require a SCEVExpander instance and could be replaced by a
-/// general code-insertion helper.
-bool SCEVExpander::hoistStep(Instruction *IncV, Instruction *InsertPos,
- const DominatorTree *DT) {
- if (DT->dominates(IncV, InsertPos))
- return true;
-
- if (!DT->dominates(InsertPos->getParent(), IncV->getParent()))
- return false;
-
- if (IncV->mayHaveSideEffects())
- return false;
-
- // Attempt to hoist IncV
- for (User::op_iterator OI = IncV->op_begin(), OE = IncV->op_end();
- OI != OE; ++OI) {
- Instruction *OInst = dyn_cast<Instruction>(OI);
- if (OInst && (OInst == InsertPos || !DT->dominates(OInst, InsertPos)))
- return false;
- }
- IncV->moveBefore(InsertPos);
- return true;
-}
-
-/// Sort Phis by integer width for replaceCongruentIVs.
-static bool width_descending(PHINode *lhs, PHINode *rhs) {
+/// Sort values by integer width for replaceCongruentIVs.
+static bool width_descending(Value *lhs, Value *rhs) {
// Put pointers at the back and make sure pointer < pointer = false.
if (!lhs->getType()->isIntegerTy() || !rhs->getType()->isIntegerTy())
return rhs->getType()->isIntegerTy() && !lhs->getType()->isIntegerTy();
/// the same context that SCEVExpander is used.
unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
SmallVectorImpl<WeakVH> &DeadInsts,
- const TargetLowering *TLI) {
+ const TargetTransformInfo *TTI) {
// Find integer phis in order of increasing width.
SmallVector<PHINode*, 8> Phis;
for (BasicBlock::iterator I = L->getHeader()->begin();
PHINode *Phi = dyn_cast<PHINode>(I); ++I) {
Phis.push_back(Phi);
}
- if (TLI)
+ if (TTI)
std::sort(Phis.begin(), Phis.end(), width_descending);
unsigned NumElim = 0;
PEnd = Phis.end(); PIter != PEnd; ++PIter) {
PHINode *Phi = *PIter;
+ // Fold constant phis. They may be congruent to other constant phis and
+ // would confuse the logic below that expects proper IVs.
+ if (Value *V = Phi->hasConstantValue()) {
+ Phi->replaceAllUsesWith(V);
+ DeadInsts.push_back(Phi);
+ ++NumElim;
+ DEBUG_WITH_TYPE(DebugType, dbgs()
+ << "INDVARS: Eliminated constant iv: " << *Phi << '\n');
+ continue;
+ }
+
if (!SE.isSCEVable(Phi->getType()))
continue;
PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
if (!OrigPhiRef) {
OrigPhiRef = Phi;
- if (Phi->getType()->isIntegerTy() && TLI
- && TLI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
+ if (Phi->getType()->isIntegerTy() && TTI
+ && TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
// This phi can be freely truncated to the narrowest phi type. Map the
// truncated expression to it so it will be reused for narrow types.
const SCEV *TruncExpr =
cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
// If this phi has the same width but is more canonical, replace the
- // original with it.
+ // original with it. As part of the "more canonical" determination,
+ // respect a prior decision to use an IV chain.
if (OrigPhiRef->getType() == Phi->getType()
- && !isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)
- && isExpandedAddRecExprPHI(Phi, IsomorphicInc, L)) {
+ && !(ChainedPhis.count(Phi)
+ || isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L))
+ && (ChainedPhis.count(Phi)
+ || isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
std::swap(OrigPhiRef, Phi);
std::swap(OrigInc, IsomorphicInc);
}
// Replacing the congruent phi is sufficient because acyclic redundancy
// elimination, CSE/GVN, should handle the rest. However, once SCEV proves
// that a phi is congruent, it's often the head of an IV user cycle that
- // is isomorphic with the original phi. So it's worth eagerly cleaning up
- // the common case of a single IV increment.
+ // is isomorphic with the original phi. It's worth eagerly cleaning up the
+ // common case of a single IV increment so that DeleteDeadPHIs can remove
+ // cycles that had postinc uses.
const SCEV *TruncExpr = SE.getTruncateOrNoop(SE.getSCEV(OrigInc),
IsomorphicInc->getType());
if (OrigInc != IsomorphicInc
- && TruncExpr == SE.getSCEV(IsomorphicInc) &&
- hoistStep(OrigInc, IsomorphicInc, DT)) {
+ && TruncExpr == SE.getSCEV(IsomorphicInc)
+ && ((isa<PHINode>(OrigInc) && isa<PHINode>(IsomorphicInc))
+ || hoistIVInc(OrigInc, IsomorphicInc))) {
DEBUG_WITH_TYPE(DebugType, dbgs()
<< "INDVARS: Eliminated congruent iv.inc: "
<< *IsomorphicInc << '\n');
Value *NewInc = OrigInc;
if (OrigInc->getType() != IsomorphicInc->getType()) {
- IRBuilder<> Builder(OrigInc->getNextNode());
+ Instruction *IP = isa<PHINode>(OrigInc)
+ ? (Instruction*)L->getHeader()->getFirstInsertionPt()
+ : OrigInc->getNextNode();
+ IRBuilder<> Builder(IP);
Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
NewInc = Builder.
CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);
}
return NumElim;
}
+
+namespace {
+// Search for a SCEV subexpression that is not safe to expand. Any expression
+// that may expand to a !isSafeToSpeculativelyExecute value is unsafe, namely
+// UDiv expressions. We don't know if the UDiv is derived from an IR divide
+// instruction, but the important thing is that we prove the denominator is
+// nonzero before expansion.
+//
+// IVUsers already checks that IV-derived expressions are safe. So this check is
+// only needed when the expression includes some subexpression that is not IV
+// derived.
+//
+// Currently, we only allow division by a nonzero constant here. If this is
+// inadequate, we could easily allow division by SCEVUnknown by using
+// ValueTracking to check isKnownNonZero().
+//
+// We cannot generally expand recurrences unless the step dominates the loop
+// header. The expander handles the special case of affine recurrences by
+// scaling the recurrence outside the loop, but this technique isn't generally
+// applicable. Expanding a nested recurrence outside a loop requires computing
+// binomial coefficients. This could be done, but the recurrence has to be in a
+// perfectly reduced form, which can't be guaranteed.
+struct SCEVFindUnsafe {
+ ScalarEvolution &SE;
+ bool IsUnsafe;
+
+ SCEVFindUnsafe(ScalarEvolution &se): SE(se), IsUnsafe(false) {}
+
+ bool follow(const SCEV *S) {
+ if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
+ const SCEVConstant *SC = dyn_cast<SCEVConstant>(D->getRHS());
+ if (!SC || SC->getValue()->isZero()) {
+ IsUnsafe = true;
+ return false;
+ }
+ }
+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
+ const SCEV *Step = AR->getStepRecurrence(SE);
+ if (!AR->isAffine() && !SE.dominates(Step, AR->getLoop()->getHeader())) {
+ IsUnsafe = true;
+ return false;
+ }
+ }
+ return true;
+ }
+ bool isDone() const { return IsUnsafe; }
+};
+}
+
+namespace llvm {
+bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE) {
+ SCEVFindUnsafe Search(SE);
+ visitAll(S, Search);
+ return !Search.IsUnsafe;
+}
+}
projects / oota-llvm.git / blobdiff