diff options
Diffstat (limited to 'llvm/lib/Analysis/ScalarEvolution.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolution.cpp | 61 |
1 files changed, 44 insertions, 17 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 0bb624c9081..8de2c15160b 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -127,6 +127,11 @@ static cl::opt<unsigned> MulOpsInlineThreshold( cl::desc("Threshold for inlining multiplication operands into a SCEV"), cl::init(1000)); +static cl::opt<unsigned> + MaxCompareDepth("scalar-evolution-max-compare-depth", cl::Hidden, + cl::desc("Maximum depth of recursive compare complexity"), + cl::init(32)); + //===----------------------------------------------------------------------===// // SCEV class definitions //===----------------------------------------------------------------------===// @@ -475,8 +480,8 @@ bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const { static int CompareValueComplexity(SmallSet<std::pair<Value *, Value *>, 8> &EqCache, const LoopInfo *const LI, Value *LV, Value *RV, - unsigned DepthLeft = 2) { - if (DepthLeft == 0 || EqCache.count({LV, RV})) + unsigned Depth) { + if (Depth > MaxCompareDepth || EqCache.count({LV, RV})) return 0; // Order pointer values after integer values. This helps SCEVExpander form @@ -537,21 +542,23 @@ CompareValueComplexity(SmallSet<std::pair<Value *, Value *>, 8> &EqCache, for (unsigned Idx : seq(0u, LNumOps)) { int Result = CompareValueComplexity(EqCache, LI, LInst->getOperand(Idx), - RInst->getOperand(Idx), DepthLeft - 1); + RInst->getOperand(Idx), Depth + 1); if (Result != 0) return Result; - EqCache.insert({LV, RV}); } } + EqCache.insert({LV, RV}); return 0; } // Return negative, zero, or positive, if LHS is less than, equal to, or greater // than RHS, respectively. A three-way result allows recursive comparisons to be // more efficient. -static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, - const SCEV *RHS) { +static int CompareSCEVComplexity( + SmallSet<std::pair<const SCEV *, const SCEV *>, 8> &EqCacheSCEV, + const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS, + unsigned Depth = 0) { // Fast-path: SCEVs are uniqued so we can do a quick equality check. if (LHS == RHS) return 0; @@ -561,6 +568,8 @@ static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, if (LType != RType) return (int)LType - (int)RType; + if (Depth > MaxCompareDepth || EqCacheSCEV.count({LHS, RHS})) + return 0; // Aside from the getSCEVType() ordering, the particular ordering // isn't very important except that it's beneficial to be consistent, // so that (a + b) and (b + a) don't end up as different expressions. @@ -570,7 +579,11 @@ static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, const SCEVUnknown *RU = cast<SCEVUnknown>(RHS); SmallSet<std::pair<Value *, Value *>, 8> EqCache; - return CompareValueComplexity(EqCache, LI, LU->getValue(), RU->getValue()); + int X = CompareValueComplexity(EqCache, LI, LU->getValue(), RU->getValue(), + Depth + 1); + if (X == 0) + EqCacheSCEV.insert({LHS, RHS}); + return X; } case scConstant: { @@ -605,11 +618,12 @@ static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, // Lexicographically compare. for (unsigned i = 0; i != LNumOps; ++i) { - long X = CompareSCEVComplexity(LI, LA->getOperand(i), RA->getOperand(i)); + int X = CompareSCEVComplexity(EqCacheSCEV, LI, LA->getOperand(i), + RA->getOperand(i), Depth + 1); if (X != 0) return X; } - + EqCacheSCEV.insert({LHS, RHS}); return 0; } @@ -628,11 +642,13 @@ static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, for (unsigned i = 0; i != LNumOps; ++i) { if (i >= RNumOps) return 1; - long X = CompareSCEVComplexity(LI, LC->getOperand(i), RC->getOperand(i)); + int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getOperand(i), + RC->getOperand(i), Depth + 1); if (X != 0) return X; } - return (int)LNumOps - (int)RNumOps; + EqCacheSCEV.insert({LHS, RHS}); + return 0; } case scUDivExpr: { @@ -640,10 +656,15 @@ static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS); // Lexicographically compare udiv expressions. - long X = CompareSCEVComplexity(LI, LC->getLHS(), RC->getLHS()); + int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getLHS(), RC->getLHS(), + Depth + 1); if (X != 0) return X; - return CompareSCEVComplexity(LI, LC->getRHS(), RC->getRHS()); + X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getRHS(), RC->getRHS(), + Depth + 1); + if (X == 0) + EqCacheSCEV.insert({LHS, RHS}); + return X; } case scTruncate: @@ -653,7 +674,11 @@ static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS); // Compare cast expressions by operand. - return CompareSCEVComplexity(LI, LC->getOperand(), RC->getOperand()); + int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getOperand(), + RC->getOperand(), Depth + 1); + if (X == 0) + EqCacheSCEV.insert({LHS, RHS}); + return X; } case scCouldNotCompute: @@ -675,19 +700,21 @@ static int CompareSCEVComplexity(const LoopInfo *const LI, const SCEV *LHS, static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops, LoopInfo *LI) { if (Ops.size() < 2) return; // Noop + + SmallSet<std::pair<const SCEV *, const SCEV *>, 8> EqCache; if (Ops.size() == 2) { // This is the common case, which also happens to be trivially simple. // Special case it. const SCEV *&LHS = Ops[0], *&RHS = Ops[1]; - if (CompareSCEVComplexity(LI, RHS, LHS) < 0) + if (CompareSCEVComplexity(EqCache, LI, RHS, LHS) < 0) std::swap(LHS, RHS); return; } // Do the rough sort by complexity. std::stable_sort(Ops.begin(), Ops.end(), - [LI](const SCEV *LHS, const SCEV *RHS) { - return CompareSCEVComplexity(LI, LHS, RHS) < 0; + [&EqCache, LI](const SCEV *LHS, const SCEV *RHS) { + return CompareSCEVComplexity(EqCache, LI, LHS, RHS) < 0; }); // Now that we are sorted by complexity, group elements of the same |
