diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index d6adbec02ac..63761d42723 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -973,6 +973,21 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) { if (Instruction *NarrowDiv = narrowUDivURem(I, Builder)) return NarrowDiv; + // If the udiv operands are non-overflowing multiplies with a common operand, + // then eliminate the common factor: + // (A * B) / (A * X) --> B / X (and commuted variants) + // TODO: The code would be reduced if we had m_c_NUWMul pattern matching. + // TODO: If -reassociation handled this generally, we could remove this. + Value *A, *B; + if (match(Op0, m_NUWMul(m_Value(A), m_Value(B)))) { + if (match(Op1, m_NUWMul(m_Specific(A), m_Value(X))) || + match(Op1, m_NUWMul(m_Value(X), m_Specific(A)))) + return BinaryOperator::CreateUDiv(B, X); + if (match(Op1, m_NUWMul(m_Specific(B), m_Value(X))) || + match(Op1, m_NUWMul(m_Value(X), m_Specific(B)))) + return BinaryOperator::CreateUDiv(A, X); + } + // (LHS udiv (select (select (...)))) -> (LHS >> (select (select (...)))) SmallVector<UDivFoldAction, 6> UDivActions; if (visitUDivOperand(Op0, Op1, I, UDivActions)) |
