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Diffstat (limited to 'lib/Analysis/InstructionSimplify.cpp')
| -rw-r--r-- | lib/Analysis/InstructionSimplify.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index 1d4ff0fc9e..f737354b36 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -593,6 +593,12 @@ static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, match(Op0, m_Add(m_Specific(Op1), m_Value(X)))) return X; + // (X*2) - X -> X + // (X<<1) - X -> X + if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) || + match(Op0, m_Shl(m_Specific(Op1), m_One()))) + return Op1; + // i1 sub -> xor. if (MaxRecurse && Op0->getType()->isIntegerTy(1)) if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1)) |