When complicated expressions are broken down into subexpressions
with multiplication by constants distributed through, occasionally those subexpressions can include both x and -x. For now, if this condition is discovered within LSR, just prune such cases away, as they won't be profitable. This fixes a "zero allocated in a base register" assertion failure. llvm-svn: 96177
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@ -2012,8 +2012,14 @@ void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx,
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F.BaseRegs.push_back(BaseReg);
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}
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if (Ops.size() > 1) {
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F.BaseRegs.push_back(SE.getAddExpr(Ops));
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(void)InsertFormula(LU, LUIdx, F);
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const SCEV *Sum = SE.getAddExpr(Ops);
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// TODO: If Sum is zero, it probably means ScalarEvolution missed an
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// opportunity to fold something. For now, just ignore such cases
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// rather than procede with zero in a register.
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if (!Sum->isZero()) {
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F.BaseRegs.push_back(Sum);
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(void)InsertFormula(LU, LUIdx, F);
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}
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}
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}
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