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LoopVectorize: Remove quadratic behavior the local CSE.
Doing this with a hash map doesn't change behavior and avoids calling isIdenticalTo O(n^2) times. This should probably eventually move into a utility class shared with EarlyCSE and the limited CSE in the SLPVectorizer. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193926 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -48,6 +48,7 @@
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#include "llvm/Transforms/Vectorize.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/EquivalenceClasses.h"
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#include "llvm/ADT/Hashing.h"
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#include "llvm/ADT/MapVector.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/SmallPtrSet.h"
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@ -2055,38 +2056,51 @@ Value *createMinMaxOp(IRBuilder<> &Builder,
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return Select;
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}
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namespace {
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struct CSEDenseMapInfo {
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static bool canHandle(Instruction *I) {
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return isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
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isa<ShuffleVectorInst>(I) || isa<GetElementPtrInst>(I);
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}
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static inline Instruction *getEmptyKey() {
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return DenseMapInfo<Instruction *>::getEmptyKey();
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}
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static inline Instruction *getTombstoneKey() {
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return DenseMapInfo<Instruction *>::getTombstoneKey();
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}
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static unsigned getHashValue(Instruction *I) {
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assert(canHandle(I) && "Unknown instruction!");
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return hash_combine(I->getOpcode(), hash_combine_range(I->value_op_begin(),
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I->value_op_end()));
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}
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static bool isEqual(Instruction *LHS, Instruction *RHS) {
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if (LHS == getEmptyKey() || RHS == getEmptyKey() ||
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LHS == getTombstoneKey() || RHS == getTombstoneKey())
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return LHS == RHS;
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return LHS->isIdenticalTo(RHS);
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}
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};
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}
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///\brief Perform cse of induction variable instructions.
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static void cse(BasicBlock *BB) {
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// Perform simple cse.
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SmallPtrSet<Instruction*, 16> Visited;
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SmallVector<Instruction*, 16> ToRemove;
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
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Instruction *In = I;
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SmallDenseMap<Instruction *, Instruction *, 4, CSEDenseMapInfo> CSEMap;
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
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Instruction *In = I++;
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if (!isa<InsertElementInst>(In) && !isa<ExtractElementInst>(In) &&
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!isa<ShuffleVectorInst>(In) && !isa<GetElementPtrInst>(In))
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continue;
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if (!CSEDenseMapInfo::canHandle(In))
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continue;
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// Check if we can replace this instruction with any of the
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// visited instructions.
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for (SmallPtrSet<Instruction*, 16>::iterator v = Visited.begin(),
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ve = Visited.end(); v != ve; ++v) {
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if (In->isIdenticalTo(*v)) {
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In->replaceAllUsesWith(*v);
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ToRemove.push_back(In);
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In = 0;
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break;
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}
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}
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if (In)
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Visited.insert(In);
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// Check if we can replace this instruction with any of the
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// visited instructions.
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if (Instruction *V = CSEMap.lookup(In)) {
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In->replaceAllUsesWith(V);
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In->eraseFromParent();
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continue;
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}
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}
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// Erase all of the instructions that we RAUWed.
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for (SmallVectorImpl<Instruction *>::iterator v = ToRemove.begin(),
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ve = ToRemove.end(); v != ve; ++v) {
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assert((*v)->getNumUses() == 0 && "Can't remove instructions with uses");
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(*v)->eraseFromParent();
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CSEMap[In] = In;
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}
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}
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