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LoopVectorize: Remove quadratic behavior the local CSE.

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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
This commit is contained in:
Benjamin Kramer 2013-11-02 13:39:00 +00:00
parent bd2affeab4
commit ff566d8f44
1 changed files with 40 additions and 26 deletions
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66
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -48,6 +48,7 @@
#include "llvm/Transforms/Vectorize.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/EquivalenceClasses.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
@ -2055,38 +2056,51 @@ Value *createMinMaxOp(IRBuilder<> &Builder,
return Select;
}
namespace {
struct CSEDenseMapInfo {
static bool canHandle(Instruction *I) {
return isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
isa<ShuffleVectorInst>(I) || isa<GetElementPtrInst>(I);
}
static inline Instruction *getEmptyKey() {
return DenseMapInfo<Instruction *>::getEmptyKey();
}
static inline Instruction *getTombstoneKey() {
return DenseMapInfo<Instruction *>::getTombstoneKey();
}
static unsigned getHashValue(Instruction *I) {
assert(canHandle(I) && "Unknown instruction!");
return hash_combine(I->getOpcode(), hash_combine_range(I->value_op_begin(),
I->value_op_end()));
}
static bool isEqual(Instruction *LHS, Instruction *RHS) {
if (LHS == getEmptyKey() || RHS == getEmptyKey() ||
LHS == getTombstoneKey() || RHS == getTombstoneKey())
return LHS == RHS;
return LHS->isIdenticalTo(RHS);
}
};
}
///\brief Perform cse of induction variable instructions.
static void cse(BasicBlock *BB) {
// Perform simple cse.
SmallPtrSet<Instruction*, 16> Visited;
SmallVector<Instruction*, 16> ToRemove;
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
Instruction *In = I;
SmallDenseMap<Instruction *, Instruction *, 4, CSEDenseMapInfo> CSEMap;
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
Instruction *In = I++;
if (!isa<InsertElementInst>(In) && !isa<ExtractElementInst>(In) &&
!isa<ShuffleVectorInst>(In) && !isa<GetElementPtrInst>(In))
continue;
if (!CSEDenseMapInfo::canHandle(In))
continue;
// Check if we can replace this instruction with any of the
// visited instructions.
for (SmallPtrSet<Instruction*, 16>::iterator v = Visited.begin(),
ve = Visited.end(); v != ve; ++v) {
if (In->isIdenticalTo(*v)) {
In->replaceAllUsesWith(*v);
ToRemove.push_back(In);
In = 0;
break;
}
}
if (In)
Visited.insert(In);
// Check if we can replace this instruction with any of the
// visited instructions.
if (Instruction *V = CSEMap.lookup(In)) {
In->replaceAllUsesWith(V);
In->eraseFromParent();
continue;
}
}
// Erase all of the instructions that we RAUWed.
for (SmallVectorImpl<Instruction *>::iterator v = ToRemove.begin(),
ve = ToRemove.end(); v != ve; ++v) {
assert((*v)->getNumUses() == 0 && "Can't remove instructions with uses");
(*v)->eraseFromParent();
CSEMap[In] = In;
}
}