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author | Chris Lattner <sabre@nondot.org> | 2005-10-26 17:18:16 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2005-10-26 17:18:16 +0000 |
commit | e9f15e538a87dcc92880ebd1ca5c3e88f1e1cb53 (patch) | |
tree | e6b386a60a96c93784d7a2d19983751854ac27f4 /lib/Transforms | |
parent | a7ad198f896d29aac57f48220ecefb8a51163393 (diff) | |
download | external_llvm-e9f15e538a87dcc92880ebd1ca5c3e88f1e1cb53.tar.gz external_llvm-e9f15e538a87dcc92880ebd1ca5c3e88f1e1cb53.tar.bz2 external_llvm-e9f15e538a87dcc92880ebd1ca5c3e88f1e1cb53.zip |
fold nested and's early to avoid inefficiencies in MaskedValueIsZero. This
fixes a very slow compile in PR639.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24011 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms')
-rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 9ba0512a78..f332509689 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -1725,6 +1725,15 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) { // and X, -1 == X if (AndRHS->isAllOnesValue()) return ReplaceInstUsesWith(I, Op0); + + // and (and X, c1), c2 -> and (x, c1&c2). Handle this case here, before + // calling MaskedValueIsZero, to avoid inefficient cases where we traipse + // through many levels of ands. + { + Value *X; ConstantInt *C1; + if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1)))) + return BinaryOperator::createAnd(X, ConstantExpr::getAnd(C1, AndRHS)); + } if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |