[llvm-commits] [llvm] r136100 - in /llvm/trunk: include/llvm/Analysis/ScalarEvolution.h lib/Analysis/ScalarEvolution.cpp
Andrew Trick
atrick at apple.com
Tue Jul 26 10:19:55 PDT 2011
Author: atrick
Date: Tue Jul 26 12:19:55 2011
New Revision: 136100
URL: http://llvm.org/viewvc/llvm-project?rev=136100&view=rev
Log:
SCEV: Added a data structure for storing not-taken info per loop
exit. Added an interfaces for querying either the loop's exact/max
backedge taken count or a specific loop exit's not-taken count.
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=136100&r1=136099&r2=136100&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Tue Jul 26 12:19:55 2011
@@ -241,31 +241,93 @@
///
ValueExprMapType ValueExprMap;
+ /// ExitLimit - Information about the number of loop iterations for
+ /// which a loop exit's branch condition evaluates to the not-taken path.
+ /// This is a temporary pair of exact and max expressions that are
+ /// eventually summarized in ExitNotTakenInfo and BackedgeTakenInfo.
+ struct ExitLimit {
+ const SCEV *Exact;
+ const SCEV *Max;
+
+ /*implicit*/ ExitLimit(const SCEV *E) : Exact(E), Max(E) {}
+
+ ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {}
+
+ /// hasAnyInfo - Test whether this ExitLimit contains any computed
+ /// information, or whether it's all SCEVCouldNotCompute values.
+ bool hasAnyInfo() const {
+ return !isa<SCEVCouldNotCompute>(Exact) ||
+ !isa<SCEVCouldNotCompute>(Max);
+ }
+ };
+
+ /// ExitNotTakenInfo - Information about the number of times a particular
+ /// loop exit may be reached before exiting the loop.
+ struct ExitNotTakenInfo {
+ BasicBlock *ExitBlock;
+ const SCEV *ExactNotTaken;
+ PointerIntPair<ExitNotTakenInfo*, 1> NextExit;
+
+ ExitNotTakenInfo() : ExitBlock(0), ExactNotTaken(0) {}
+
+ /// isCompleteList - Return true if all loop exits are computable.
+ bool isCompleteList() const {
+ return NextExit.getInt() == 0;
+ }
+
+ void setIncomplete() { NextExit.setInt(1); }
+
+ /// getNextExit - Return a pointer to the next exit's not-taken info.
+ ExitNotTakenInfo *getNextExit() const {
+ return NextExit.getPointer();
+ }
+
+ void setNextExit(ExitNotTakenInfo *ENT) { NextExit.setPointer(ENT); }
+ };
+
/// BackedgeTakenInfo - Information about the backedge-taken count
/// of a loop. This currently includes an exact count and a maximum count.
///
- struct BackedgeTakenInfo {
- /// Exact - An expression indicating the exact backedge-taken count of
- /// the loop if it is known, or a SCEVCouldNotCompute otherwise.
- const SCEV *Exact;
+ class BackedgeTakenInfo {
+ /// ExitNotTaken - A list of computable exits and their not-taken counts.
+ /// Loops almost never have more than one computable exit.
+ ExitNotTakenInfo ExitNotTaken;
/// Max - An expression indicating the least maximum backedge-taken
/// count of the loop that is known, or a SCEVCouldNotCompute.
const SCEV *Max;
- /*implicit*/ BackedgeTakenInfo(const SCEV *exact) :
- Exact(exact), Max(exact) {}
+ public:
+ BackedgeTakenInfo() : Max(0) {}
- BackedgeTakenInfo(const SCEV *exact, const SCEV *max) :
- Exact(exact), Max(max) {}
+ /// Initialize BackedgeTakenInfo from a list of exact exit counts.
+ BackedgeTakenInfo(
+ SmallVectorImpl< std::pair<BasicBlock *, const SCEV *> > &ExitCounts,
+ bool Complete, const SCEV *MaxCount);
/// hasAnyInfo - Test whether this BackedgeTakenInfo contains any
/// computed information, or whether it's all SCEVCouldNotCompute
/// values.
bool hasAnyInfo() const {
- return !isa<SCEVCouldNotCompute>(Exact) ||
- !isa<SCEVCouldNotCompute>(Max);
+ return ExitNotTaken.ExitBlock || !isa<SCEVCouldNotCompute>(Max);
}
+
+ /// getExact - Return an expression indicating the exact backedge-taken
+ /// count of the loop if it is known, or SCEVCouldNotCompute
+ /// otherwise. This is the number of times the loop header can be
+ /// guaranteed to execute, minus one.
+ const SCEV *getExact(ScalarEvolution *SE) const;
+
+ /// getExact - Return the number of times this loop exit may fall through
+ /// to the back edge. The loop is guaranteed not to exit via this block
+ /// before this number of iterations, but may exit via another block.
+ const SCEV *getExact(BasicBlock *ExitBlock, ScalarEvolution *SE) const;
+
+ /// getMax - Get the max backedge taken count for the loop.
+ const SCEV *getMax(ScalarEvolution *SE) const;
+
+ /// clear - Invalidate this result and free associated memory.
+ void clear();
};
/// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
@@ -365,64 +427,59 @@
/// loop will iterate.
BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L);
- /// ComputeBackedgeTakenCountFromExit - Compute the number of times the
- /// backedge of the specified loop will execute if it exits via the
- /// specified block.
- BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L,
- BasicBlock *ExitingBlock);
-
- /// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the
- /// backedge of the specified loop will execute if its exit condition
- /// were a conditional branch of ExitCond, TBB, and FBB.
- BackedgeTakenInfo
- ComputeBackedgeTakenCountFromExitCond(const Loop *L,
- Value *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB);
-
- /// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of
- /// times the backedge of the specified loop will execute if its exit
- /// condition were a conditional branch of the ICmpInst ExitCond, TBB,
- /// and FBB.
- BackedgeTakenInfo
- ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
- ICmpInst *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB);
+ /// ComputeExitLimit - Compute the number of times the backedge of the
+ /// specified loop will execute if it exits via the specified block.
+ ExitLimit ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock);
+
+ /// ComputeExitLimitFromCond - Compute the number of times the backedge of
+ /// the specified loop will execute if its exit condition were a conditional
+ /// branch of ExitCond, TBB, and FBB.
+ ExitLimit ComputeExitLimitFromCond(const Loop *L,
+ Value *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB);
+
+ /// ComputeExitLimitFromICmp - Compute the number of times the backedge of
+ /// the specified loop will execute if its exit condition were a conditional
+ /// branch of the ICmpInst ExitCond, TBB, and FBB.
+ ExitLimit ComputeExitLimitFromICmp(const Loop *L,
+ ICmpInst *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB);
- /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition
+ /// ComputeLoadConstantCompareExitLimit - Given an exit condition
/// of 'icmp op load X, cst', try to see if we can compute the
/// backedge-taken count.
- BackedgeTakenInfo
- ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI,
- Constant *RHS,
- const Loop *L,
- ICmpInst::Predicate p);
+ ExitLimit ComputeLoadConstantCompareExitLimit(LoadInst *LI,
+ Constant *RHS,
+ const Loop *L,
+ ICmpInst::Predicate p);
- /// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute
- /// a constant number of times (the condition evolves only from constants),
+ /// ComputeExitCountExhaustively - If the loop is known to execute a
+ /// constant number of times (the condition evolves only from constants),
/// try to evaluate a few iterations of the loop until we get the exit
/// condition gets a value of ExitWhen (true or false). If we cannot
- /// evaluate the backedge-taken count of the loop, return CouldNotCompute.
- const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L,
- Value *Cond,
- bool ExitWhen);
+ /// evaluate the exit count of the loop, return CouldNotCompute.
+ const SCEV *ComputeExitCountExhaustively(const Loop *L,
+ Value *Cond,
+ bool ExitWhen);
- /// HowFarToZero - Return the number of times a backedge comparing the
- /// specified value to zero will execute. If not computable, return
+ /// HowFarToZero - Return the number of times an exit condition comparing
+ /// the specified value to zero will execute. If not computable, return
/// CouldNotCompute.
- BackedgeTakenInfo HowFarToZero(const SCEV *V, const Loop *L);
+ ExitLimit HowFarToZero(const SCEV *V, const Loop *L);
- /// HowFarToNonZero - Return the number of times a backedge checking the
- /// specified value for nonzero will execute. If not computable, return
+ /// HowFarToNonZero - Return the number of times an exit condition checking
+ /// the specified value for nonzero will execute. If not computable, return
/// CouldNotCompute.
- BackedgeTakenInfo HowFarToNonZero(const SCEV *V, const Loop *L);
+ ExitLimit HowFarToNonZero(const SCEV *V, const Loop *L);
- /// HowManyLessThans - Return the number of times a backedge containing the
- /// specified less-than comparison will execute. If not computable, return
- /// CouldNotCompute. isSigned specifies whether the less-than is signed.
- BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
- const Loop *L, bool isSigned);
+ /// HowManyLessThans - Return the number of times an exit condition
+ /// containing the specified less-than comparison will execute. If not
+ /// computable, return CouldNotCompute. isSigned specifies whether the
+ /// less-than is signed.
+ ExitLimit HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
+ const Loop *L, bool isSigned);
/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
/// (which may not be an immediate predecessor) which has exactly one
@@ -653,6 +710,11 @@
bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
+ // getExitCount - Get the expression for the number of loop iterations for
+ // which this loop is guaranteed not to exit via ExitBlock. Otherwise return
+ // SCEVCouldNotCompute.
+ const SCEV *getExitCount(Loop *L, BasicBlock *ExitBlock);
+
/// getBackedgeTakenCount - If the specified loop has a predictable
/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
/// object. The backedge-taken count is the number of times the loop header
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=136100&r1=136099&r2=136100&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Tue Jul 26 12:19:55 2011
@@ -3813,6 +3813,13 @@
// Iteration Count Computation Code
//
+// getExitCount - Get the expression for the number of loop iterations for which
+// this loop is guaranteed not to exit via ExitBlock. Otherwise return
+// SCEVCouldNotCompute.
+const SCEV *ScalarEvolution::getExitCount(Loop *L, BasicBlock *ExitBlock) {
+ return getBackedgeTakenInfo(L).getExact(ExitBlock, this);
+}
+
/// getBackedgeTakenCount - If the specified loop has a predictable
/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
/// object. The backedge-taken count is the number of times the loop header
@@ -3825,14 +3832,14 @@
/// hasLoopInvariantBackedgeTakenCount).
///
const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
- return getBackedgeTakenInfo(L).Exact;
+ return getBackedgeTakenInfo(L).getExact(this);
}
/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
/// return the least SCEV value that is known never to be less than the
/// actual backedge taken count.
const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
- return getBackedgeTakenInfo(L).Max;
+ return getBackedgeTakenInfo(L).getMax(this);
}
/// PushLoopPHIs - Push PHI nodes in the header of the given loop
@@ -3849,33 +3856,31 @@
const ScalarEvolution::BackedgeTakenInfo &
ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
- // Initially insert a CouldNotCompute for this loop. If the insertion
+ // Initially insert an invalid entry for this loop. If the insertion
// succeeds, proceed to actually compute a backedge-taken count and
// update the value. The temporary CouldNotCompute value tells SCEV
// code elsewhere that it shouldn't attempt to request a new
// backedge-taken count, which could result in infinite recursion.
std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
- BackedgeTakenCounts.insert(std::make_pair(L, getCouldNotCompute()));
+ BackedgeTakenCounts.insert(std::make_pair(L, BackedgeTakenInfo()));
if (!Pair.second)
return Pair.first->second;
- BackedgeTakenInfo Result = getCouldNotCompute();
- BackedgeTakenInfo Computed = ComputeBackedgeTakenCount(L);
- if (Computed.Exact != getCouldNotCompute()) {
- assert(isLoopInvariant(Computed.Exact, L) &&
- isLoopInvariant(Computed.Max, L) &&
+ // ComputeBackedgeTakenCount may allocate memory for its result. Inserting it
+ // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
+ // must be cleared in this scope.
+ BackedgeTakenInfo Result = ComputeBackedgeTakenCount(L);
+
+ if (Result.getExact(this) != getCouldNotCompute()) {
+ assert(isLoopInvariant(Result.getExact(this), L) &&
+ isLoopInvariant(Result.getMax(this), L) &&
"Computed backedge-taken count isn't loop invariant for loop!");
++NumTripCountsComputed;
-
- // Update the value in the map.
- Result = Computed;
- } else {
- if (Computed.Max != getCouldNotCompute())
- // Update the value in the map.
- Result = Computed;
- if (isa<PHINode>(L->getHeader()->begin()))
- // Only count loops that have phi nodes as not being computable.
- ++NumTripCountsNotComputed;
+ }
+ else if (Result.getMax(this) == getCouldNotCompute() &&
+ isa<PHINode>(L->getHeader()->begin())) {
+ // Only count loops that have phi nodes as not being computable.
+ ++NumTripCountsNotComputed;
}
// Now that we know more about the trip count for this loop, forget any
@@ -3883,7 +3888,7 @@
// conservative estimates made without the benefit of trip count
// information. This is similar to the code in forgetLoop, except that
// it handles SCEVUnknown PHI nodes specially.
- if (Computed.hasAnyInfo()) {
+ if (Result.hasAnyInfo()) {
SmallVector<Instruction *, 16> Worklist;
PushLoopPHIs(L, Worklist);
@@ -3928,7 +3933,12 @@
/// compute a trip count, or if the loop is deleted.
void ScalarEvolution::forgetLoop(const Loop *L) {
// Drop any stored trip count value.
- BackedgeTakenCounts.erase(L);
+ DenseMap<const Loop*, BackedgeTakenInfo>::iterator BTCPos =
+ BackedgeTakenCounts.find(L);
+ if (BTCPos != BackedgeTakenCounts.end()) {
+ BTCPos->second.clear();
+ BackedgeTakenCounts.erase(BTCPos);
+ }
// Drop information about expressions based on loop-header PHIs.
SmallVector<Instruction *, 16> Worklist;
@@ -3984,6 +3994,84 @@
}
}
+/// getExact - Get the exact loop backedge taken count considering all loop
+/// exits. If all exits are computable, this is the minimum computed count.
+const SCEV *
+ScalarEvolution::BackedgeTakenInfo::getExact(ScalarEvolution *SE) const {
+ // If any exits were not computable, the loop is not computable.
+ if (!ExitNotTaken.isCompleteList()) return SE->getCouldNotCompute();
+
+ // We need at least one computable exit.
+ if (!ExitNotTaken.ExitBlock) return SE->getCouldNotCompute();
+ assert(ExitNotTaken.ExactNotTaken && "uninitialized not-taken info");
+
+ const SCEV *BECount = 0;
+ for (const ExitNotTakenInfo *ENT = &ExitNotTaken;
+ ENT != 0; ENT = ENT->getNextExit()) {
+
+ assert(ENT->ExactNotTaken != SE->getCouldNotCompute() && "bad exit SCEV");
+
+ if (!BECount)
+ BECount = ENT->ExactNotTaken;
+ else
+ BECount = SE->getUMinFromMismatchedTypes(BECount, ENT->ExactNotTaken);
+ }
+ return BECount;
+}
+
+/// getExact - Get the exact not taken count for this loop exit.
+const SCEV *
+ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitBlock,
+ ScalarEvolution *SE) const {
+ for (const ExitNotTakenInfo *ENT = &ExitNotTaken;
+ ENT != 0; ENT = ENT->getNextExit()) {
+
+ if (ENT->ExitBlock == ExitBlock)
+ return ENT->ExactNotTaken;
+ }
+ return SE->getCouldNotCompute();
+}
+
+/// getMax - Get the max backedge taken count for the loop.
+const SCEV *
+ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
+ return Max ? Max : SE->getCouldNotCompute();
+}
+
+/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
+/// computable exit into a persistent ExitNotTakenInfo array.
+ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
+ SmallVectorImpl< std::pair<BasicBlock *, const SCEV *> > &ExitCounts,
+ bool Complete, const SCEV *MaxCount) : Max(MaxCount) {
+
+ if (!Complete)
+ ExitNotTaken.setIncomplete();
+
+ unsigned NumExits = ExitCounts.size();
+ if (NumExits == 0) return;
+
+ ExitNotTaken.ExitBlock = ExitCounts[0].first;
+ ExitNotTaken.ExactNotTaken = ExitCounts[0].second;
+ if (NumExits == 1) return;
+
+ // Handle the rare case of multiple computable exits.
+ ExitNotTakenInfo *ENT = new ExitNotTakenInfo[NumExits-1];
+
+ ExitNotTakenInfo *PrevENT = &ExitNotTaken;
+ for (unsigned i = 1; i < NumExits; ++i, PrevENT = ENT, ++ENT) {
+ PrevENT->setNextExit(ENT);
+ ENT->ExitBlock = ExitCounts[i].first;
+ ENT->ExactNotTaken = ExitCounts[i].second;
+ }
+}
+
+/// clear - Invalidate this result and free the ExitNotTakenInfo array.
+void ScalarEvolution::BackedgeTakenInfo::clear() {
+ ExitNotTaken.ExitBlock = 0;
+ ExitNotTaken.ExactNotTaken = 0;
+ delete[] ExitNotTaken.getNextExit();
+}
+
/// ComputeBackedgeTakenCount - Compute the number of times the backedge
/// of the specified loop will execute.
ScalarEvolution::BackedgeTakenInfo
@@ -3992,38 +4080,31 @@
L->getExitingBlocks(ExitingBlocks);
// Examine all exits and pick the most conservative values.
- const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
- bool CouldNotComputeBECount = false;
+ bool CouldComputeBECount = true;
+ SmallVector<std::pair<BasicBlock *, const SCEV *>, 4> ExitCounts;
for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
- BackedgeTakenInfo NewBTI =
- ComputeBackedgeTakenCountFromExit(L, ExitingBlocks[i]);
-
- if (NewBTI.Exact == getCouldNotCompute()) {
+ ExitLimit EL = ComputeExitLimit(L, ExitingBlocks[i]);
+ if (EL.Exact == getCouldNotCompute())
// We couldn't compute an exact value for this exit, so
// we won't be able to compute an exact value for the loop.
- CouldNotComputeBECount = true;
- BECount = getCouldNotCompute();
- } else if (!CouldNotComputeBECount) {
- if (BECount == getCouldNotCompute())
- BECount = NewBTI.Exact;
- else
- BECount = getUMinFromMismatchedTypes(BECount, NewBTI.Exact);
- }
+ CouldComputeBECount = false;
+ else
+ ExitCounts.push_back(std::make_pair(ExitingBlocks[i], EL.Exact));
+
if (MaxBECount == getCouldNotCompute())
- MaxBECount = NewBTI.Max;
- else if (NewBTI.Max != getCouldNotCompute())
- MaxBECount = getUMinFromMismatchedTypes(MaxBECount, NewBTI.Max);
+ MaxBECount = EL.Max;
+ else if (EL.Max != getCouldNotCompute())
+ MaxBECount = getUMinFromMismatchedTypes(MaxBECount, EL.Max);
}
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return BackedgeTakenInfo(ExitCounts, CouldComputeBECount, MaxBECount);
}
-/// ComputeBackedgeTakenCountFromExit - Compute the number of times the backedge
-/// of the specified loop will execute if it exits via the specified block.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExit(const Loop *L,
- BasicBlock *ExitingBlock) {
+/// ComputeExitLimit - Compute the number of times the backedge of the specified
+/// loop will execute if it exits via the specified block.
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock) {
// Okay, we've chosen an exiting block. See what condition causes us to
// exit at this block.
@@ -4081,95 +4162,91 @@
}
// Proceed to the next level to examine the exit condition expression.
- return ComputeBackedgeTakenCountFromExitCond(L, ExitBr->getCondition(),
- ExitBr->getSuccessor(0),
- ExitBr->getSuccessor(1));
+ return ComputeExitLimitFromCond(L, ExitBr->getCondition(),
+ ExitBr->getSuccessor(0),
+ ExitBr->getSuccessor(1));
}
-/// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the
+/// ComputeExitLimitFromCond - Compute the number of times the
/// backedge of the specified loop will execute if its exit condition
/// were a conditional branch of ExitCond, TBB, and FBB.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L,
- Value *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB) {
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeExitLimitFromCond(const Loop *L,
+ Value *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB) {
// Check if the controlling expression for this loop is an And or Or.
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
if (BO->getOpcode() == Instruction::And) {
// Recurse on the operands of the and.
- BackedgeTakenInfo BTI0 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(0), TBB, FBB);
- BackedgeTakenInfo BTI1 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(1), TBB, FBB);
+ ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB);
+ ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB);
const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
if (L->contains(TBB)) {
// Both conditions must be true for the loop to continue executing.
// Choose the less conservative count.
- if (BTI0.Exact == getCouldNotCompute() ||
- BTI1.Exact == getCouldNotCompute())
+ if (EL0.Exact == getCouldNotCompute() ||
+ EL1.Exact == getCouldNotCompute())
BECount = getCouldNotCompute();
else
- BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max == getCouldNotCompute())
- MaxBECount = BTI1.Max;
- else if (BTI1.Max == getCouldNotCompute())
- MaxBECount = BTI0.Max;
+ BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
+ if (EL0.Max == getCouldNotCompute())
+ MaxBECount = EL1.Max;
+ else if (EL1.Max == getCouldNotCompute())
+ MaxBECount = EL0.Max;
else
- MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
} else {
// Both conditions must be true at the same time for the loop to exit.
// For now, be conservative.
assert(L->contains(FBB) && "Loop block has no successor in loop!");
- if (BTI0.Max == BTI1.Max)
- MaxBECount = BTI0.Max;
- if (BTI0.Exact == BTI1.Exact)
- BECount = BTI0.Exact;
+ if (EL0.Max == EL1.Max)
+ MaxBECount = EL0.Max;
+ if (EL0.Exact == EL1.Exact)
+ BECount = EL0.Exact;
}
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return ExitLimit(BECount, MaxBECount);
}
if (BO->getOpcode() == Instruction::Or) {
// Recurse on the operands of the or.
- BackedgeTakenInfo BTI0 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(0), TBB, FBB);
- BackedgeTakenInfo BTI1 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(1), TBB, FBB);
+ ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB);
+ ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB);
const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
if (L->contains(FBB)) {
// Both conditions must be false for the loop to continue executing.
// Choose the less conservative count.
- if (BTI0.Exact == getCouldNotCompute() ||
- BTI1.Exact == getCouldNotCompute())
+ if (EL0.Exact == getCouldNotCompute() ||
+ EL1.Exact == getCouldNotCompute())
BECount = getCouldNotCompute();
else
- BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max == getCouldNotCompute())
- MaxBECount = BTI1.Max;
- else if (BTI1.Max == getCouldNotCompute())
- MaxBECount = BTI0.Max;
+ BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
+ if (EL0.Max == getCouldNotCompute())
+ MaxBECount = EL1.Max;
+ else if (EL1.Max == getCouldNotCompute())
+ MaxBECount = EL0.Max;
else
- MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
+ MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
} else {
// Both conditions must be false at the same time for the loop to exit.
// For now, be conservative.
assert(L->contains(TBB) && "Loop block has no successor in loop!");
- if (BTI0.Max == BTI1.Max)
- MaxBECount = BTI0.Max;
- if (BTI0.Exact == BTI1.Exact)
- BECount = BTI0.Exact;
+ if (EL0.Max == EL1.Max)
+ MaxBECount = EL0.Max;
+ if (EL0.Exact == EL1.Exact)
+ BECount = EL0.Exact;
}
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return ExitLimit(BECount, MaxBECount);
}
}
// With an icmp, it may be feasible to compute an exact backedge-taken count.
// Proceed to the next level to examine the icmp.
if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond))
- return ComputeBackedgeTakenCountFromExitCondICmp(L, ExitCondICmp, TBB, FBB);
+ return ComputeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB);
// Check for a constant condition. These are normally stripped out by
// SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
@@ -4185,17 +4262,17 @@
}
// If it's not an integer or pointer comparison then compute it the hard way.
- return ComputeBackedgeTakenCountExhaustively(L, ExitCond, !L->contains(TBB));
+ return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
}
-/// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of times the
+/// ComputeExitLimitFromICmp - Compute the number of times the
/// backedge of the specified loop will execute if its exit condition
/// were a conditional branch of the ICmpInst ExitCond, TBB, and FBB.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
- ICmpInst *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB) {
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeExitLimitFromICmp(const Loop *L,
+ ICmpInst *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB) {
// If the condition was exit on true, convert the condition to exit on false
ICmpInst::Predicate Cond;
@@ -4207,8 +4284,8 @@
// Handle common loops like: for (X = "string"; *X; ++X)
if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
- BackedgeTakenInfo ItCnt =
- ComputeLoadConstantCompareBackedgeTakenCount(LI, RHS, L, Cond);
+ ExitLimit ItCnt =
+ ComputeLoadConstantCompareExitLimit(LI, RHS, L, Cond);
if (ItCnt.hasAnyInfo())
return ItCnt;
}
@@ -4247,36 +4324,36 @@
switch (Cond) {
case ICmpInst::ICMP_NE: { // while (X != Y)
// Convert to: while (X-Y != 0)
- BackedgeTakenInfo BTI = HowFarToZero(getMinusSCEV(LHS, RHS), L);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_EQ: { // while (X == Y)
// Convert to: while (X-Y == 0)
- BackedgeTakenInfo BTI = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_SLT: {
- BackedgeTakenInfo BTI = HowManyLessThans(LHS, RHS, L, true);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowManyLessThans(LHS, RHS, L, true);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_SGT: {
- BackedgeTakenInfo BTI = HowManyLessThans(getNotSCEV(LHS),
+ ExitLimit EL = HowManyLessThans(getNotSCEV(LHS),
getNotSCEV(RHS), L, true);
- if (BTI.hasAnyInfo()) return BTI;
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_ULT: {
- BackedgeTakenInfo BTI = HowManyLessThans(LHS, RHS, L, false);
- if (BTI.hasAnyInfo()) return BTI;
+ ExitLimit EL = HowManyLessThans(LHS, RHS, L, false);
+ if (EL.hasAnyInfo()) return EL;
break;
}
case ICmpInst::ICMP_UGT: {
- BackedgeTakenInfo BTI = HowManyLessThans(getNotSCEV(LHS),
+ ExitLimit EL = HowManyLessThans(getNotSCEV(LHS),
getNotSCEV(RHS), L, false);
- if (BTI.hasAnyInfo()) return BTI;
+ if (EL.hasAnyInfo()) return EL;
break;
}
default:
@@ -4290,8 +4367,7 @@
#endif
break;
}
- return
- ComputeBackedgeTakenCountExhaustively(L, ExitCond, !L->contains(TBB));
+ return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
}
static ConstantInt *
@@ -4338,15 +4414,16 @@
return Init;
}
-/// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition of
+/// ComputeLoadConstantCompareExitLimit - Given an exit condition of
/// 'icmp op load X, cst', try to see if we can compute the backedge
/// execution count.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeLoadConstantCompareBackedgeTakenCount(
- LoadInst *LI,
- Constant *RHS,
- const Loop *L,
- ICmpInst::Predicate predicate) {
+ScalarEvolution::ExitLimit
+ScalarEvolution::ComputeLoadConstantCompareExitLimit(
+ LoadInst *LI,
+ Constant *RHS,
+ const Loop *L,
+ ICmpInst::Predicate predicate) {
+
if (LI->isVolatile()) return getCouldNotCompute();
// Check to see if the loaded pointer is a getelementptr of a global.
@@ -4547,15 +4624,14 @@
}
}
-/// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute a
+/// ComputeExitCountExhaustively - If the loop is known to execute a
/// constant number of times (the condition evolves only from constants),
/// try to evaluate a few iterations of the loop until we get the exit
/// condition gets a value of ExitWhen (true or false). If we cannot
/// evaluate the trip count of the loop, return getCouldNotCompute().
-const SCEV *
-ScalarEvolution::ComputeBackedgeTakenCountExhaustively(const Loop *L,
- Value *Cond,
- bool ExitWhen) {
+const SCEV * ScalarEvolution::ComputeExitCountExhaustively(const Loop *L,
+ Value *Cond,
+ bool ExitWhen) {
PHINode *PN = getConstantEvolvingPHI(Cond, L);
if (PN == 0) return getCouldNotCompute();
@@ -4949,7 +5025,7 @@
/// now expressed as a single expression, V = x-y. So the exit test is
/// effectively V != 0. We know and take advantage of the fact that this
/// expression only being used in a comparison by zero context.
-ScalarEvolution::BackedgeTakenInfo
+ScalarEvolution::ExitLimit
ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L) {
// If the value is a constant
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
@@ -5061,7 +5137,7 @@
/// HowFarToNonZero - Return the number of times a backedge checking the
/// specified value for nonzero will execute. If not computable, return
/// CouldNotCompute
-ScalarEvolution::BackedgeTakenInfo
+ScalarEvolution::ExitLimit
ScalarEvolution::HowFarToNonZero(const SCEV *V, const Loop *L) {
// Loops that look like: while (X == 0) are very strange indeed. We don't
// handle them yet except for the trivial case. This could be expanded in the
@@ -5774,7 +5850,7 @@
/// HowManyLessThans - Return the number of times a backedge containing the
/// specified less-than comparison will execute. If not computable, return
/// CouldNotCompute.
-ScalarEvolution::BackedgeTakenInfo
+ScalarEvolution::ExitLimit
ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
const Loop *L, bool isSigned) {
// Only handle: "ADDREC < LoopInvariant".
@@ -5881,7 +5957,7 @@
if (isa<SCEVCouldNotCompute>(MaxBECount))
MaxBECount = BECount;
- return BackedgeTakenInfo(BECount, MaxBECount);
+ return ExitLimit(BECount, MaxBECount);
}
return getCouldNotCompute();
@@ -6089,6 +6165,15 @@
FirstUnknown = 0;
ValueExprMap.clear();
+
+ // Free any extra memory created for ExitNotTakenInfo in the unlikely event
+ // that a loop had multiple computable exits.
+ for (DenseMap<const Loop*, BackedgeTakenInfo>::iterator I =
+ BackedgeTakenCounts.begin(), E = BackedgeTakenCounts.end();
+ I != E; ++I) {
+ I->second.clear();
+ }
+
BackedgeTakenCounts.clear();
ConstantEvolutionLoopExitValue.clear();
ValuesAtScopes.clear();
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