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Revert r219223, it creates invalid PHI nodes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219587 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -76,16 +76,6 @@ STATISTIC(NumSinkCommons, "Number of common instructions sunk down to the end bl
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STATISTIC(NumSpeculations, "Number of speculative executed instructions");
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namespace {
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// The first field contains the value that the switch produces when a certain
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// case group is selected, and the second field is a vector containing the cases
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// composing the case group.
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typedef SmallVector<std::pair<Constant *, SmallVector<ConstantInt *, 4>>, 2>
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SwitchCaseResultVectorTy;
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// The first field contains the phi node that generates a result of the switch
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// and the second field contains the value generated for a certain case in the switch
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// for that PHI.
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typedef SmallVector<std::pair<PHINode *, Constant *>, 4> SwitchCaseResultsTy;
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/// ValueEqualityComparisonCase - Represents a case of a switch.
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struct ValueEqualityComparisonCase {
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ConstantInt *Value;
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@ -3463,163 +3453,6 @@ GetCaseResults(SwitchInst *SI,
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return Res.size() > 0;
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}
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// MapCaseToResult - Helper function used to
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// add CaseVal to the list of cases that generate Result.
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static void MapCaseToResult(ConstantInt *CaseVal,
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SwitchCaseResultVectorTy &UniqueResults,
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Constant *Result) {
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for (auto &I : UniqueResults) {
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if (I.first == Result) {
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I.second.push_back(CaseVal);
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return;
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}
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}
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UniqueResults.push_back(std::make_pair(Result,
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SmallVector<ConstantInt*, 4>(1, CaseVal)));
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}
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// InitializeUniqueCases - Helper function that initializes a map containing
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// results for the PHI node of the common destination block for a switch
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// instruction. Returns false if multiple PHI nodes have been found or if
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// there is not a common destination block for the switch.
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static bool InitializeUniqueCases(
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SwitchInst *SI, const DataLayout *DL, PHINode *&PHI,
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BasicBlock *&CommonDest,
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SwitchCaseResultVectorTy &UniqueResults,
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Constant *&DefaultResult) {
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for (auto &I : SI->cases()) {
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ConstantInt *CaseVal = I.getCaseValue();
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// Resulting value at phi nodes for this case value.
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SwitchCaseResultsTy Results;
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if (!GetCaseResults(SI, CaseVal, I.getCaseSuccessor(), &CommonDest, Results,
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DL))
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return false;
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// Only one value per case is permitted
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if (Results.size() > 1)
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return false;
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MapCaseToResult(CaseVal, UniqueResults, Results.begin()->second);
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// Check the PHI consistency.
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if (!PHI)
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PHI = Results[0].first;
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else if (PHI != Results[0].first)
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return false;
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}
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// Find the default result value.
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SmallVector<std::pair<PHINode *, Constant *>, 1> DefaultResults;
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BasicBlock *DefaultDest = SI->getDefaultDest();
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GetCaseResults(SI, nullptr, SI->getDefaultDest(), &CommonDest, DefaultResults,
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DL);
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// If the default value is not found abort unless the default destination
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// is unreachable.
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DefaultResult =
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DefaultResults.size() == 1 ? DefaultResults.begin()->second : nullptr;
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if ((!DefaultResult &&
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!isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg())))
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return false;
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return true;
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}
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// ConvertTwoCaseSwitch - Helper function that checks if it is possible to
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// transform a switch with only two cases (or two cases + default)
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// that produces a result into a value select.
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// Example:
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// switch (a) {
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// case 10: %0 = icmp eq i32 %a, 10
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// return 10; %1 = select i1 %0, i32 10, i32 4
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// case 20: ----> %2 = icmp eq i32 %a, 20
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// return 2; %3 = select i1 %2, i32 2, i32 %1
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// default:
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// return 4;
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// }
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static Value *
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ConvertTwoCaseSwitch(const SwitchCaseResultVectorTy &ResultVector,
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Constant *DefaultResult, Value *Condition,
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IRBuilder<> &Builder) {
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assert(ResultVector.size() == 2 &&
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"We should have exactly two unique results at this point");
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// If we are selecting between only two cases transform into a simple
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// select or a two-way select if default is possible.
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if (ResultVector[0].second.size() == 1 &&
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ResultVector[1].second.size() == 1) {
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ConstantInt *const FirstCase = ResultVector[0].second[0];
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ConstantInt *const SecondCase = ResultVector[1].second[0];
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bool DefaultCanTrigger = DefaultResult;
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Value *SelectValue = ResultVector[1].first;
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if (DefaultCanTrigger) {
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Value *const ValueCompare =
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Builder.CreateICmpEQ(Condition, SecondCase, "switch.selectcmp");
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SelectValue = Builder.CreateSelect(ValueCompare, ResultVector[1].first,
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DefaultResult, "switch.select");
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}
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Value *const ValueCompare =
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Builder.CreateICmpEQ(Condition, FirstCase, "switch.selectcmp");
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return Builder.CreateSelect(ValueCompare, ResultVector[0].first, SelectValue,
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"switch.select");
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}
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return nullptr;
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}
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// RemoveSwitchAfterSelectConversion - Helper function to cleanup a switch
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// instruction that has been converted into a select, fixing up PHI nodes and
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// basic blocks.
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static void RemoveSwitchAfterSelectConversion(SwitchInst *SI, PHINode *PHI,
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Value *SelectValue,
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IRBuilder<> &Builder) {
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BasicBlock *SelectBB = SI->getParent();
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if (PHI->getBasicBlockIndex(SelectBB) >= 0)
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PHI->removeIncomingValue(SelectBB);
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PHI->addIncoming(SelectValue, SelectBB);
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Builder.CreateBr(PHI->getParent());
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// Remove the switch.
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for (unsigned i = 0, e = SI->getNumSuccessors(); i < e; ++i) {
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BasicBlock *Succ = SI->getSuccessor(i);
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if (Succ == PHI->getParent())
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continue;
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Succ->removePredecessor(SelectBB);
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}
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SI->eraseFromParent();
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}
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/// SwitchToSelect - If the switch is only used to initialize one or more
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/// phi nodes in a common successor block with only two different
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/// constant values, replace the switch with select.
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static bool SwitchToSelect(SwitchInst *SI, IRBuilder<> &Builder,
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const DataLayout *DL, AssumptionTracker *AT) {
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Value *const Cond = SI->getCondition();
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PHINode *PHI = nullptr;
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BasicBlock *CommonDest = nullptr;
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Constant *DefaultResult;
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SwitchCaseResultVectorTy UniqueResults;
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// Collect all the cases that will deliver the same value from the switch.
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if (!InitializeUniqueCases(SI, DL, PHI, CommonDest, UniqueResults,
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DefaultResult))
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return false;
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// Selects choose between maximum two values.
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if (UniqueResults.size() != 2)
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return false;
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assert(PHI != nullptr && "PHI for value select not found");
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Builder.SetInsertPoint(SI);
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Value *SelectValue = ConvertTwoCaseSwitch(
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UniqueResults,
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DefaultResult, Cond, Builder);
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if (SelectValue) {
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RemoveSwitchAfterSelectConversion(SI, PHI, SelectValue, Builder);
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return true;
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}
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// The switch couldn't be converted into a select.
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return false;
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}
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namespace {
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/// SwitchLookupTable - This class represents a lookup table that can be used
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/// to replace a switch.
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@ -4118,9 +3951,6 @@ bool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) {
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if (EliminateDeadSwitchCases(SI, DL, AT))
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return SimplifyCFG(BB, TTI, BonusInstThreshold, DL, AT) | true;
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if (SwitchToSelect(SI, Builder, DL, AT))
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return SimplifyCFG(BB, TTI, BonusInstThreshold, DL, AT) | true;
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if (ForwardSwitchConditionToPHI(SI))
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return SimplifyCFG(BB, TTI, BonusInstThreshold, DL, AT) | true;
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@ -47,7 +47,7 @@ T:
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}
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; PR9450
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define i32 @test4(i32 %v, i32 %w) {
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define i32 @test4(i32 %v) {
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; CHECK: entry:
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; CHECK-NEXT: switch i32 %v, label %T [
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; CHECK-NEXT: i32 3, label %V
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@ -67,7 +67,7 @@ SWITCH:
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default:
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unreachable
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U:
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ret i32 %w
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ret i32 1
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T:
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ret i32 2
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}
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@ -915,12 +915,8 @@ return:
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%x = phi i32 [ 3, %sw.default ], [ 7, %sw.bb1 ], [ 9, %entry ]
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ret i32 %x
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; CHECK-LABEL: @twocases(
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; CHECK-NOT: switch i32
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; CHECK: switch i32
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; CHECK-NOT: @switch.table
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; CHECK: %switch.selectcmp
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; CHECK-NEXT: %switch.select
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; CHECK-NEXT: %switch.selectcmp1
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; CHECK-NEXT: %switch.select2
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}
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; Don't build tables for switches with TLS variables.
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@ -1,72 +0,0 @@
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; RUN: opt < %s -simplifycfg -S | FileCheck %s
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; int foo1_with_default(int a) {
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; switch(a) {
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; case 10:
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; return 10;
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; case 20:
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; return 2;
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; }
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; return 4;
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; }
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define i32 @foo1_with_default(i32 %a) {
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; CHECK-LABEL: @foo1_with_default
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; CHECK: %switch.selectcmp = icmp eq i32 %a, 20
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; CHECK-NEXT: %switch.select = select i1 %switch.selectcmp, i32 2, i32 4
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; CHECK-NEXT: %switch.selectcmp1 = icmp eq i32 %a, 10
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; CHECK-NEXT: %switch.select2 = select i1 %switch.selectcmp1, i32 10, i32 %switch.select
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entry:
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switch i32 %a, label %sw.epilog [
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i32 10, label %sw.bb
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i32 20, label %sw.bb1
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]
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sw.bb:
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br label %return
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sw.bb1:
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br label %return
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sw.epilog:
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br label %return
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return:
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%retval.0 = phi i32 [ 4, %sw.epilog ], [ 2, %sw.bb1 ], [ 10, %sw.bb ]
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ret i32 %retval.0
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}
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; int foo1_without_default(int a) {
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; switch(a) {
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; case 10:
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; return 10;
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; case 20:
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; return 2;
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; }
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; __builtin_unreachable();
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; }
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define i32 @foo1_without_default(i32 %a) {
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; CHECK-LABEL: @foo1_without_default
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; CHECK: %switch.selectcmp = icmp eq i32 %a, 10
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; CHECK-NEXT: %switch.select = select i1 %switch.selectcmp, i32 10, i32 2
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; CHECK-NOT: %switch.selectcmp1
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entry:
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switch i32 %a, label %sw.epilog [
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i32 10, label %sw.bb
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i32 20, label %sw.bb1
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]
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sw.bb:
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br label %return
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sw.bb1:
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br label %return
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sw.epilog:
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unreachable
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return:
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%retval.0 = phi i32 [ 2, %sw.bb1 ], [ 10, %sw.bb ]
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ret i32 %retval.0
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}
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