[SCEV][NFC] More efficient caching in CompareValueComplexity
Currently, we use a set of pairs to cache responces like `CompareValueComplexity(X, Y) == 0`. If we had proved that `CompareValueComplexity(S1, S2) == 0` and `CompareValueComplexity(S2, S3) == 0`, this cache does not allow us to prove that `CompareValueComplexity(S1, S3)` is also `0`. This patch replaces this set with `EquivalenceClasses` that merges Values into equivalence sets so that any two values from the same set are equal from point of `CompareValueComplexity`. This, in particular, allows us to prove the fact from example above. Differential Revision: https://reviews.llvm.org/D40429 llvm-svn: 319153
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@ -549,10 +549,10 @@ bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
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/// Since we do not continue running this routine on expression trees once we
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/// Since we do not continue running this routine on expression trees once we
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/// have seen unequal values, there is no need to track them in the cache.
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/// have seen unequal values, there is no need to track them in the cache.
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static int
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static int
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CompareValueComplexity(SmallSet<std::pair<Value *, Value *>, 8> &EqCache,
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CompareValueComplexity(EquivalenceClasses<Value *> &EqCache,
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const LoopInfo *const LI, Value *LV, Value *RV,
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const LoopInfo *const LI, Value *LV, Value *RV,
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unsigned Depth) {
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unsigned Depth) {
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if (Depth > MaxValueCompareDepth || EqCache.count({LV, RV}))
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if (Depth > MaxValueCompareDepth || EqCache.isEquivalent(LV, RV))
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return 0;
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return 0;
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// Order pointer values after integer values. This helps SCEVExpander form
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// Order pointer values after integer values. This helps SCEVExpander form
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@ -619,7 +619,7 @@ CompareValueComplexity(SmallSet<std::pair<Value *, Value *>, 8> &EqCache,
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}
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}
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}
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}
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EqCache.insert({LV, RV});
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EqCache.unionSets(LV, RV);
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return 0;
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return 0;
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}
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}
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@ -649,7 +649,7 @@ static int CompareSCEVComplexity(
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const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
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const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
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const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
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const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
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SmallSet<std::pair<Value *, Value *>, 8> EqCache;
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EquivalenceClasses<Value *> EqCache;
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int X = CompareValueComplexity(EqCache, LI, LU->getValue(), RU->getValue(),
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int X = CompareValueComplexity(EqCache, LI, LU->getValue(), RU->getValue(),
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Depth + 1);
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Depth + 1);
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if (X == 0)
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if (X == 0)
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