From e2ff29c17c1a7c121e22789cf1654d923467b472 Mon Sep 17 00:00:00 2001 From: Anton Korobeynikov Date: Sat, 10 Mar 2007 16:46:28 +0000 Subject: [PATCH] Use range tests in LowerSwitch, where possible git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35057 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/LowerSwitch.cpp | 145 +++++++++++++++++++------ test/Transforms/LowerSwitch/feature.ll | 50 +++++++++ 2 files changed, 164 insertions(+), 31 deletions(-) create mode 100644 test/Transforms/LowerSwitch/feature.ll diff --git a/lib/Transforms/Utils/LowerSwitch.cpp b/lib/Transforms/Utils/LowerSwitch.cpp index 652833c4598..17ebd098803 100644 --- a/lib/Transforms/Utils/LowerSwitch.cpp +++ b/lib/Transforms/Utils/LowerSwitch.cpp @@ -40,26 +40,38 @@ namespace { AU.addPreservedID(LowerInvokePassID); AU.addPreservedID(LowerAllocationsID); } - - typedef std::pair Case; - typedef std::vector::iterator CaseItr; + + struct CaseRange { + Constant* Low; + Constant* High; + BasicBlock* BB; + + CaseRange(Constant* _Low = NULL, Constant* _High = NULL, + BasicBlock* _BB = NULL): + Low(_Low), High(_High), BB(_BB) { } + }; + + typedef std::vector CaseVector; + typedef std::vector::iterator CaseItr; private: void processSwitchInst(SwitchInst *SI); BasicBlock* switchConvert(CaseItr Begin, CaseItr End, Value* Val, BasicBlock* OrigBlock, BasicBlock* Default); - BasicBlock* newLeafBlock(Case& Leaf, Value* Val, + BasicBlock* newLeafBlock(CaseRange& Leaf, Value* Val, BasicBlock* OrigBlock, BasicBlock* Default); + unsigned Clusterify(CaseVector& Cases, SwitchInst *SI); }; /// The comparison function for sorting the switch case values in the vector. + /// WARNING: Case ranges should be disjoint! struct CaseCmp { - bool operator () (const LowerSwitch::Case& C1, - const LowerSwitch::Case& C2) { + bool operator () (const LowerSwitch::CaseRange& C1, + const LowerSwitch::CaseRange& C2) { - const ConstantInt* CI1 = cast(C1.first); - const ConstantInt* CI2 = cast(C2.first); - return CI1->getValue().ult(CI2->getValue()); + const ConstantInt* CI1 = cast(C1.Low); + const ConstantInt* CI2 = cast(C2.High); + return CI1->getValue().slt(CI2->getValue()); } }; @@ -91,19 +103,20 @@ bool LowerSwitch::runOnFunction(Function &F) { // operator<< - Used for debugging purposes. // -std::ostream& operator<<(std::ostream &O, - const std::vector &C) { +static std::ostream& operator<<(std::ostream &O, + const LowerSwitch::CaseVector &C) { O << "["; - for (std::vector::const_iterator B = C.begin(), + for (LowerSwitch::CaseVector::const_iterator B = C.begin(), E = C.end(); B != E; ) { - O << *B->first; + O << *B->Low << " -" << *B->High; if (++B != E) O << ", "; } return O << "]"; } -OStream& operator<<(OStream &O, const std::vector &C) { + +static OStream& operator<<(OStream &O, const LowerSwitch::CaseVector &C) { if (O.stream()) *O.stream() << C; return O; } @@ -121,14 +134,16 @@ BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, return newLeafBlock(*Begin, Val, OrigBlock, Default); unsigned Mid = Size / 2; - std::vector LHS(Begin, Begin + Mid); + std::vector LHS(Begin, Begin + Mid); DOUT << "LHS: " << LHS << "\n"; - std::vector RHS(Begin + Mid, End); + std::vector RHS(Begin + Mid, End); DOUT << "RHS: " << RHS << "\n"; - Case& Pivot = *(Begin + Mid); + CaseRange& Pivot = *(Begin + Mid); DEBUG( DOUT << "Pivot ==> " - << cast(Pivot.first)->getValue().toStringSigned(10) + << cast(Pivot.Low)->getValue().toStringSigned(10) + << " -" + << cast(Pivot.High)->getValue().toStringSigned(10) << "\n"); BasicBlock* LBranch = switchConvert(LHS.begin(), LHS.end(), Val, @@ -142,7 +157,7 @@ BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, BasicBlock* NewNode = new BasicBlock("NodeBlock"); F->getBasicBlockList().insert(OrigBlock->getNext(), NewNode); - ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_ULT, Val, Pivot.first, "Pivot"); + ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT, Val, Pivot.Low, "Pivot"); NewNode->getInstList().push_back(Comp); new BranchInst(LBranch, RBranch, Comp, NewNode); return NewNode; @@ -154,7 +169,7 @@ BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, // can't be another valid case value, so the jump to the "default" branch // is warranted. // -BasicBlock* LowerSwitch::newLeafBlock(Case& Leaf, Value* Val, +BasicBlock* LowerSwitch::newLeafBlock(CaseRange& Leaf, Value* Val, BasicBlock* OrigBlock, BasicBlock* Default) { @@ -162,19 +177,49 @@ BasicBlock* LowerSwitch::newLeafBlock(Case& Leaf, Value* Val, BasicBlock* NewLeaf = new BasicBlock("LeafBlock"); F->getBasicBlockList().insert(OrigBlock->getNext(), NewLeaf); - // Make the seteq instruction... - ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_EQ, Val, - Leaf.first, "SwitchLeaf"); - NewLeaf->getInstList().push_back(Comp); + // Emit comparison + ICmpInst* Comp = NULL; + if (Leaf.Low == Leaf.High) { + // Make the seteq instruction... + Comp = new ICmpInst(ICmpInst::ICMP_EQ, Val, Leaf.Low, + "SwitchLeaf", NewLeaf); + } else { + // Make range comparison + if (cast(Leaf.Low)->isMinValue(true /*isSigned*/)) { + // Val >= Min && Val <= Hi --> Val <= Hi + Comp = new ICmpInst(ICmpInst::ICMP_SLE, Val, Leaf.High, + "SwitchLeaf", NewLeaf); + } else if (cast(Leaf.Low)->isZero()) { + // Val >= 0 && Val <= Hi --> Val <=u Hi + Comp = new ICmpInst(ICmpInst::ICMP_ULE, Val, Leaf.High, + "SwitchLeaf", NewLeaf); + } else { + // Emit V-Lo <=u Hi-Lo + Constant* NegLo = ConstantExpr::getNeg(Leaf.Low); + Instruction* Add = BinaryOperator::createAdd(Val, NegLo, + Val->getName()+".off", + NewLeaf); + Constant *UpperBound = ConstantExpr::getAdd(NegLo, Leaf.High); + Comp = new ICmpInst(ICmpInst::ICMP_ULE, Add, UpperBound, + "SwitchLeaf", NewLeaf); + } + } // Make the conditional branch... - BasicBlock* Succ = Leaf.second; + BasicBlock* Succ = Leaf.BB; new BranchInst(Succ, Default, Comp, NewLeaf); // If there were any PHI nodes in this successor, rewrite one entry // from OrigBlock to come from NewLeaf. for (BasicBlock::iterator I = Succ->begin(); isa(I); ++I) { PHINode* PN = cast(I); + // Remove all but one incoming entries from the cluster + uint64_t Range = cast(Leaf.High)->getSExtValue() - + cast(Leaf.Low)->getSExtValue(); + for (uint64_t j = 0; j < Range; ++j) { + PN->removeIncomingValue(OrigBlock); + } + int BlockIdx = PN->getBasicBlockIndex(OrigBlock); assert(BlockIdx != -1 && "Switch didn't go to this successor??"); PN->setIncomingBlock((unsigned)BlockIdx, NewLeaf); @@ -183,6 +228,44 @@ BasicBlock* LowerSwitch::newLeafBlock(Case& Leaf, Value* Val, return NewLeaf; } +// Clusterify - Transform simple list of Cases into list of CaseRange's +unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) { + unsigned numCmps = 0; + + // Start with "simple" cases + for (unsigned i = 1; i < SI->getNumSuccessors(); ++i) + Cases.push_back(CaseRange(SI->getSuccessorValue(i), + SI->getSuccessorValue(i), + SI->getSuccessor(i))); + sort(Cases.begin(), Cases.end(), CaseCmp()); + + // Merge case into clusters + if (Cases.size()>=2) + for (CaseItr I=Cases.begin(), J=++(Cases.begin()), E=Cases.end(); J!=E; ) { + int64_t nextValue = cast(J->Low)->getSExtValue(); + int64_t currentValue = cast(I->High)->getSExtValue(); + BasicBlock* nextBB = J->BB; + BasicBlock* currentBB = I->BB; + + // If the two neighboring cases go to the same destination, merge them + // into a single case. + if ((nextValue-currentValue==1) && (currentBB == nextBB)) { + I->High = J->High; + J = Cases.erase(J); + } else { + I = J++; + } + } + + for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) { + if (I->Low != I->High) + // A range counts double, since it requires two compares. + ++numCmps; + } + + return numCmps; +} + // processSwitchInst - Replace the specified switch instruction with a sequence // of chained if-then insts in a balanced binary search. // @@ -216,14 +299,14 @@ void LowerSwitch::processSwitchInst(SwitchInst *SI) { PN->setIncomingBlock((unsigned)BlockIdx, NewDefault); } - std::vector Cases; + // Prepare cases vector. + CaseVector Cases; + unsigned numCmps = Clusterify(Cases, SI); - // Expand comparisons for all of the non-default cases... - for (unsigned i = 1; i < SI->getNumSuccessors(); ++i) - Cases.push_back(Case(SI->getSuccessorValue(i), SI->getSuccessor(i))); - - std::sort(Cases.begin(), Cases.end(), CaseCmp()); + DOUT << "Clusterify finished. Total clusters: " << Cases.size() + << ". Total compares: " << numCmps << "\n"; DOUT << "Cases: " << Cases << "\n"; + BasicBlock* SwitchBlock = switchConvert(Cases.begin(), Cases.end(), Val, OrigBlock, NewDefault); diff --git a/test/Transforms/LowerSwitch/feature.ll b/test/Transforms/LowerSwitch/feature.ll new file mode 100644 index 00000000000..cb88e31c16c --- /dev/null +++ b/test/Transforms/LowerSwitch/feature.ll @@ -0,0 +1,50 @@ +; RUN: llvm-as %s -o - | opt -lowerswitch | llvm-dis | grep slt | wc -l | grep 10 && +; RUN: llvm-as %s -o - | opt -lowerswitch | llvm-dis | grep ule | wc -l | grep 3 && +; RUN: llvm-as %s -o - | opt -lowerswitch | llvm-dis | grep eq | wc -l | grep 9 + +define i32 @main(i32 %tmp158) { +entry: + switch i32 %tmp158, label %bb336 [ + i32 -2, label %bb338 + i32 -3, label %bb338 + i32 -4, label %bb338 + i32 -5, label %bb338 + i32 -6, label %bb338 + i32 0, label %bb338 + i32 1, label %bb338 + i32 2, label %bb338 + i32 3, label %bb338 + i32 4, label %bb338 + i32 5, label %bb338 + i32 6, label %bb338 + i32 7, label %bb + i32 8, label %bb338 + i32 9, label %bb322 + i32 10, label %bb324 + i32 11, label %bb326 + i32 12, label %bb328 + i32 13, label %bb330 + i32 14, label %bb332 + i32 15, label %bb334 + ] +bb: + ret i32 2 +bb322: + ret i32 3 +bb324: + ret i32 4 +bb326: + ret i32 5 +bb328: + ret i32 6 +bb330: + ret i32 7 +bb332: + ret i32 8 +bb334: + ret i32 9 +bb336: + ret i32 10 +bb338: + ret i32 11 +}