[PATCH] Enable unrolling of multi-exit loops
Jingyue Wu
jingyue at google.com
Tue Sep 30 21:17:43 PDT 2014
LGTM. You may want to mention your change to MustExit and ControlsExit in the description. Thanks for working on this!
================
Comment at: lib/Analysis/ScalarEvolution.cpp:4723
@@ -4469,3 +4722,3 @@
//
// (a) Its ExitLimit.MustExit flag must be set which indicates that the exit
// test condition cannot be skipped (the tested variable has unit stride or
----------------
Since MustExit is gone, comments need to be updated.
================
Comment at: lib/Analysis/ScalarEvolution.cpp:6045
@@ -5800,3 +6044,3 @@
const SCEV *Exact =
- getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
- return ExitLimit(Exact, Exact, /*MustExit=*/false);
+ getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
+ return ExitLimit(Exact, Exact);
----------------
Can we use getUDivExactExpr when R is zero?
================
Comment at: lib/Analysis/ScalarEvolution.cpp:7104
@@ -6868,213 +7103,3 @@
R1->getValue(), R2->getValue()))) {
- if (CB->getZExtValue() == false)
- std::swap(R1, R2); // R1 is the minimum root now.
-
- // Make sure the root is not off by one. The returned iteration should
- // not be in the range, but the previous one should be. When solving
- // for "X*X < 5", for example, we should not return a root of 2.
- ConstantInt *R1Val = EvaluateConstantChrecAtConstant(this,
- R1->getValue(),
- SE);
- if (Range.contains(R1Val->getValue())) {
- // The next iteration must be out of the range...
- ConstantInt *NextVal =
- ConstantInt::get(SE.getContext(), R1->getValue()->getValue()+1);
-
- R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
- if (!Range.contains(R1Val->getValue()))
- return SE.getConstant(NextVal);
- return SE.getCouldNotCompute(); // Something strange happened
- }
-
- // If R1 was not in the range, then it is a good return value. Make
- // sure that R1-1 WAS in the range though, just in case.
- ConstantInt *NextVal =
- ConstantInt::get(SE.getContext(), R1->getValue()->getValue()-1);
- R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
- if (Range.contains(R1Val->getValue()))
- return R1;
- return SE.getCouldNotCompute(); // Something strange happened
- }
- }
- }
-
- return SE.getCouldNotCompute();
-}
-
-namespace {
-struct FindUndefs {
- bool Found;
- FindUndefs() : Found(false) {}
-
- bool follow(const SCEV *S) {
- if (const SCEVUnknown *C = dyn_cast<SCEVUnknown>(S)) {
- if (isa<UndefValue>(C->getValue()))
- Found = true;
- } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
- if (isa<UndefValue>(C->getValue()))
- Found = true;
- }
-
- // Keep looking if we haven't found it yet.
- return !Found;
- }
- bool isDone() const {
- // Stop recursion if we have found an undef.
- return Found;
- }
-};
-}
-
-// Return true when S contains at least an undef value.
-static inline bool
-containsUndefs(const SCEV *S) {
- FindUndefs F;
- SCEVTraversal<FindUndefs> ST(F);
- ST.visitAll(S);
-
- return F.Found;
-}
-
-namespace {
-// Collect all steps of SCEV expressions.
-struct SCEVCollectStrides {
- ScalarEvolution &SE;
- SmallVectorImpl<const SCEV *> &Strides;
-
- SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S)
- : SE(SE), Strides(S) {}
-
- bool follow(const SCEV *S) {
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
- Strides.push_back(AR->getStepRecurrence(SE));
- return true;
- }
- bool isDone() const { return false; }
-};
-
-// Collect all SCEVUnknown and SCEVMulExpr expressions.
-struct SCEVCollectTerms {
- SmallVectorImpl<const SCEV *> &Terms;
-
- SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T)
- : Terms(T) {}
-
- bool follow(const SCEV *S) {
- if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S)) {
- if (!containsUndefs(S))
- Terms.push_back(S);
-
- // Stop recursion: once we collected a term, do not walk its operands.
- return false;
- }
-
- // Keep looking.
- return true;
- }
- bool isDone() const { return false; }
-};
-}
-
-/// Find parametric terms in this SCEVAddRecExpr.
-void SCEVAddRecExpr::collectParametricTerms(
- ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &Terms) const {
- SmallVector<const SCEV *, 4> Strides;
- SCEVCollectStrides StrideCollector(SE, Strides);
- visitAll(this, StrideCollector);
-
- DEBUG({
- dbgs() << "Strides:\n";
- for (const SCEV *S : Strides)
- dbgs() << *S << "\n";
- });
-
- for (const SCEV *S : Strides) {
- SCEVCollectTerms TermCollector(Terms);
- visitAll(S, TermCollector);
- }
-
- DEBUG({
- dbgs() << "Terms:\n";
- for (const SCEV *T : Terms)
- dbgs() << *T << "\n";
- });
-}
-
-static const APInt srem(const SCEVConstant *C1, const SCEVConstant *C2) {
- APInt A = C1->getValue()->getValue();
- APInt B = C2->getValue()->getValue();
- uint32_t ABW = A.getBitWidth();
- uint32_t BBW = B.getBitWidth();
-
- if (ABW > BBW)
- B = B.sext(ABW);
- else if (ABW < BBW)
- A = A.sext(BBW);
-
- return APIntOps::srem(A, B);
-}
-
-static const APInt sdiv(const SCEVConstant *C1, const SCEVConstant *C2) {
- APInt A = C1->getValue()->getValue();
- APInt B = C2->getValue()->getValue();
- uint32_t ABW = A.getBitWidth();
- uint32_t BBW = B.getBitWidth();
-
- if (ABW > BBW)
- B = B.sext(ABW);
- else if (ABW < BBW)
- A = A.sext(BBW);
-
- return APIntOps::sdiv(A, B);
-}
-
-namespace {
-struct FindSCEVSize {
- int Size;
- FindSCEVSize() : Size(0) {}
-
- bool follow(const SCEV *S) {
- ++Size;
- // Keep looking at all operands of S.
- return true;
- }
- bool isDone() const {
- return false;
- }
-};
-}
-
-// Returns the size of the SCEV S.
-static inline int sizeOfSCEV(const SCEV *S) {
- FindSCEVSize F;
- SCEVTraversal<FindSCEVSize> ST(F);
- ST.visitAll(S);
- return F.Size;
-}
-
-namespace {
-
-struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> {
-public:
- // Computes the Quotient and Remainder of the division of Numerator by
- // Denominator.
- static void divide(ScalarEvolution &SE, const SCEV *Numerator,
- const SCEV *Denominator, const SCEV **Quotient,
- const SCEV **Remainder) {
- assert(Numerator && Denominator && "Uninitialized SCEV");
-
- SCEVDivision D(SE, Numerator, Denominator);
-
- // Check for the trivial case here to avoid having to check for it in the
- // rest of the code.
- if (Numerator == Denominator) {
- *Quotient = D.One;
- *Remainder = D.Zero;
- return;
- }
-
- if (Numerator->isZero()) {
- *Quotient = D.Zero;
- *Remainder = D.Zero;
- return;
- }
+ if (CB->getZExtValue() == false)
+ std::swap(R1, R2); // R1 is the minimum root now.
----------------
Looks like the diff tool is not doing a good job :) Are the remaining differences in this file simply copy and paste?
http://reviews.llvm.org/D5550
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