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-rw-r--r--lib/Analysis/ScalarEvolutionExpander.cpp229
-rw-r--r--lib/Transforms/Scalar/IndVarSimplify.cpp8
-rw-r--r--lib/Transforms/Scalar/LoopStrengthReduce.cpp26
3 files changed, 137 insertions, 126 deletions
diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index e2f75aa0ea..0f7475673a 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -38,8 +38,11 @@ Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
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, fix it. All new or reused
+ // instructions must strictly dominate the Builder's InsertPt to
+ // ensure that the expression's expansion dominates its uses.
+ if (BasicBlock::iterator(CI) != IP
+ || IP == Builder.GetInsertPoint()) {
// 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.
@@ -867,61 +870,108 @@ bool SCEVExpander::isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV,
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) {
- if (ChainedPhis.count(PN))
- return true;
+/// 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->properlyDominates(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->properlyDominates(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->properlyDominates(IncV, InsertPos))
+ return true;
+
+ // InsertPos must itself dominate IncV so that IncV's new position satisfies
+ // its existing users.
+ if (!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->properlyDominates(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.
@@ -981,26 +1031,28 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
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;
}
}
@@ -1404,10 +1456,7 @@ Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
}
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);
}
@@ -1445,8 +1494,11 @@ Value *SCEVExpander::expand(const SCEV *S) {
// 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;
}
@@ -1481,23 +1533,9 @@ void SCEVExpander::rememberInstruction(Value *I) {
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);
}
@@ -1525,49 +1563,6 @@ SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
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) {
- // Phi nodes are strangely positional but don't follow normal rules for
- // instruction dominance. Handle them immediately.
- if (isa<PHINode>(InsertPos))
- return isa<PHINode>(IncV);
- else if (isa<PHINode>(IncV))
- return false;
-
- 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 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.
@@ -1632,10 +1627,13 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
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);
}
@@ -1649,7 +1647,8 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
IsomorphicInc->getType());
if (OrigInc != IsomorphicInc
&& TruncExpr == SE.getSCEV(IsomorphicInc)
- && hoistStep(OrigInc, IsomorphicInc, DT)) {
+ && ((isa<PHINode>(OrigInc) && isa<PHINode>(IsomorphicInc))
+ || hoistIVInc(OrigInc, IsomorphicInc))) {
DEBUG_WITH_TYPE(DebugType, dbgs()
<< "INDVARS: Eliminated congruent iv.inc: "
<< *IsomorphicInc << '\n');
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 6d52b22e01..ac1209f46f 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -846,7 +846,7 @@ protected:
const SCEVAddRecExpr* GetExtendedOperandRecurrence(NarrowIVDefUse DU);
- Instruction *WidenIVUse(NarrowIVDefUse DU);
+ Instruction *WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter);
void pushNarrowIVUsers(Instruction *NarrowDef, Instruction *WideDef);
};
@@ -990,7 +990,7 @@ const SCEVAddRecExpr *WidenIV::GetWideRecurrence(Instruction *NarrowUse) {
/// WidenIVUse - Determine whether an individual user of the narrow IV can be
/// widened. If so, return the wide clone of the user.
-Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU) {
+Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter) {
// Stop traversing the def-use chain at inner-loop phis or post-loop phis.
if (isa<PHINode>(DU.NarrowUse) &&
@@ -1058,7 +1058,7 @@ Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU) {
// NarrowUse.
Instruction *WideUse = 0;
if (WideAddRec == WideIncExpr
- && SCEVExpander::hoistStep(WideInc, DU.NarrowUse, DT))
+ && Rewriter.hoistIVInc(WideInc, DU.NarrowUse))
WideUse = WideInc;
else {
WideUse = CloneIVUser(DU);
@@ -1163,7 +1163,7 @@ PHINode *WidenIV::CreateWideIV(SCEVExpander &Rewriter) {
// Process a def-use edge. This may replace the use, so don't hold a
// use_iterator across it.
- Instruction *WideUse = WidenIVUse(DU);
+ Instruction *WideUse = WidenIVUse(DU, Rewriter);
// Follow all def-use edges from the previous narrow use.
if (WideUse)
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index baf566906b..42f45ae627 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1573,9 +1573,11 @@ class LSRInstance {
BasicBlock::iterator
HoistInsertPosition(BasicBlock::iterator IP,
const SmallVectorImpl<Instruction *> &Inputs) const;
- BasicBlock::iterator AdjustInsertPositionForExpand(BasicBlock::iterator IP,
- const LSRFixup &LF,
- const LSRUse &LU) const;
+ BasicBlock::iterator
+ AdjustInsertPositionForExpand(BasicBlock::iterator IP,
+ const LSRFixup &LF,
+ const LSRUse &LU,
+ SCEVExpander &Rewriter) const;
Value *Expand(const LSRFixup &LF,
const Formula &F,
@@ -4131,9 +4133,10 @@ LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,
/// AdjustInsertPositionForExpand - Determine an input position which will be
/// dominated by the operands and which will dominate the result.
BasicBlock::iterator
-LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator IP,
+LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP,
const LSRFixup &LF,
- const LSRUse &LU) const {
+ const LSRUse &LU,
+ SCEVExpander &Rewriter) const {
// Collect some instructions which must be dominated by the
// expanding replacement. These must be dominated by any operands that
// will be required in the expansion.
@@ -4168,9 +4171,13 @@ LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator IP,
}
}
+ assert(!isa<PHINode>(LowestIP) && !isa<LandingPadInst>(LowestIP)
+ && !isa<DbgInfoIntrinsic>(LowestIP) &&
+ "Insertion point must be a normal instruction");
+
// Then, climb up the immediate dominator tree as far as we can go while
// still being dominated by the input positions.
- IP = HoistInsertPosition(IP, Inputs);
+ BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs);
// Don't insert instructions before PHI nodes.
while (isa<PHINode>(IP)) ++IP;
@@ -4181,6 +4188,11 @@ LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator IP,
// Ignore debug intrinsics.
while (isa<DbgInfoIntrinsic>(IP)) ++IP;
+ // Set IP below instructions recently inserted by SCEVExpander. This keeps the
+ // IP consistent across expansions and allows the previously inserted
+ // instructions to be reused by subsequent expansion.
+ while (Rewriter.isInsertedInstruction(IP) && IP != LowestIP) ++IP;
+
return IP;
}
@@ -4195,7 +4207,7 @@ Value *LSRInstance::Expand(const LSRFixup &LF,
// Determine an input position which will be dominated by the operands and
// which will dominate the result.
- IP = AdjustInsertPositionForExpand(IP, LF, LU);
+ IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter);
// Inform the Rewriter if we have a post-increment use, so that it can
// perform an advantageous expansion.
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-04-27 07:04:40 +0000