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Add a method to ScalarEvolution for telling it when a loop has been
modified in a way that may effect the trip count calculation. Change IndVars to use this method when it rewrites pointer or floating-point induction variables instead of using a doInitialization method to sneak these changes in before ScalarEvolution has a chance to see the loop. This eliminates the need for LoopPass to depend on ScalarEvolution. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64810 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -301,6 +301,11 @@ namespace llvm {
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/// an analyzable loop-invariant iteration count.
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bool hasLoopInvariantIterationCount(const Loop *L) const;
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/// forgetLoopIterationCount - This method should be called by the
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/// client when it has changed a loop in a way that may effect
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/// ScalarEvolution's ability to compute a trip count.
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void forgetLoopIterationCount(const Loop *L);
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/// deleteValueFromRecords - This method should be called by the
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/// client before it removes a Value from the program, to make sure
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/// that no dangling references are left around.
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@ -14,7 +14,6 @@
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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@ -173,8 +172,6 @@ void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
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// LPPassManager needs LoopInfo. In the long term LoopInfo class will
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// become part of LPPassManager.
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Info.addRequired<LoopInfo>();
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// Used by IndVar doInitialization.
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Info.addRequired<ScalarEvolution>();
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Info.setPreservesAll();
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}
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@ -1453,6 +1453,11 @@ namespace {
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/// an analyzable loop-invariant iteration count.
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bool hasLoopInvariantIterationCount(const Loop *L);
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/// forgetLoopIterationCount - This method should be called by the
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/// client when it has changed a loop in a way that may effect
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/// ScalarEvolution's ability to compute a trip count.
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void forgetLoopIterationCount(const Loop *L);
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/// getIterationCount - If the specified loop has a predictable iteration
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/// count, return it. Note that it is not valid to call this method on a
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/// loop without a loop-invariant iteration count.
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@ -1931,6 +1936,13 @@ SCEVHandle ScalarEvolutionsImpl::getIterationCount(const Loop *L) {
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return I->second;
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}
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/// forgetLoopIterationCount - This method should be called by the
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/// client when it has changed a loop in a way that may effect
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/// ScalarEvolution's ability to compute a trip count.
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void ScalarEvolutionsImpl::forgetLoopIterationCount(const Loop *L) {
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IterationCounts.erase(L);
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}
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/// ComputeIterationCount - Compute the number of times the specified loop
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/// will iterate.
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SCEVHandle ScalarEvolutionsImpl::ComputeIterationCount(const Loop *L) {
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@ -3091,6 +3103,10 @@ bool ScalarEvolution::hasLoopInvariantIterationCount(const Loop *L) const {
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return !isa<SCEVCouldNotCompute>(getIterationCount(L));
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}
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void ScalarEvolution::forgetLoopIterationCount(const Loop *L) {
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return ((ScalarEvolutionsImpl*)Impl)->forgetLoopIterationCount(L);
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}
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SCEVHandle ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) const {
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return ((ScalarEvolutionsImpl*)Impl)->getSCEVAtScope(getSCEV(V), L);
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}
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@ -74,8 +74,8 @@ namespace {
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static char ID; // Pass identification, replacement for typeid
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IndVarSimplify() : LoopPass(&ID) {}
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bool runOnLoop(Loop *L, LPPassManager &LPM);
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bool doInitialization(Loop *L, LPPassManager &LPM);
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virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<ScalarEvolution>();
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AU.addRequiredID(LCSSAID);
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@ -88,6 +88,8 @@ namespace {
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private:
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void RewriteNonIntegerIVs(Loop *L);
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void EliminatePointerRecurrence(PHINode *PN, BasicBlock *Preheader,
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SmallPtrSet<Instruction*, 16> &DeadInsts);
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void LinearFunctionTestReplace(Loop *L, SCEVHandle IterationCount,
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@ -411,16 +413,13 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L, SCEV *IterationCount) {
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DeleteTriviallyDeadInstructions(InstructionsToDelete);
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}
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bool IndVarSimplify::doInitialization(Loop *L, LPPassManager &LPM) {
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Changed = false;
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void IndVarSimplify::RewriteNonIntegerIVs(Loop *L) {
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// First step. Check to see if there are any trivial GEP pointer recurrences.
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// If there are, change them into integer recurrences, permitting analysis by
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// the SCEV routines.
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//
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BasicBlock *Header = L->getHeader();
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BasicBlock *Preheader = L->getLoopPreheader();
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SE = &LPM.getAnalysis<ScalarEvolution>();
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SmallPtrSet<Instruction*, 16> DeadInsts;
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for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
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@ -431,10 +430,14 @@ bool IndVarSimplify::doInitialization(Loop *L, LPPassManager &LPM) {
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HandleFloatingPointIV(L, PN, DeadInsts);
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}
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// If the loop previously had a pointer or floating-point IV, ScalarEvolution
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// may not have been able to compute a trip count. Now that we've done some
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// re-writing, the trip count may be computable.
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if (Changed)
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SE->forgetLoopIterationCount(L);
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if (!DeadInsts.empty())
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DeleteTriviallyDeadInstructions(DeadInsts);
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return Changed;
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}
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/// getEffectiveIndvarType - Determine the widest type that the
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@ -594,8 +597,12 @@ static void TestOrigIVForWrap(const Loop *L,
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bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
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LI = &getAnalysis<LoopInfo>();
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SE = &getAnalysis<ScalarEvolution>();
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Changed = false;
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// If there are any floating-point or pointer recurrences, attempt to
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// transform them to use integer recurrences.
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RewriteNonIntegerIVs(L);
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BasicBlock *Header = L->getHeader();
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BasicBlock *ExitingBlock = L->getExitingBlock();
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SmallPtrSet<Instruction*, 16> DeadInsts;
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