diff options
| author | Chris Lattner <sabre@nondot.org> | 2005-01-19 17:29:49 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2005-01-19 17:29:49 +0000 |
| commit | 88218ef706ba6fffc3b3f3c894910eea0f59abb1 (patch) | |
| tree | bc89d71f6389dbd9448a93dab8905d5fd02883b6 /lib/CodeGen/SelectionDAG/SelectionDAG.cpp | |
| parent | c3c021bcadd580a0764e12527f58a94389ae81ce (diff) | |
Know some simple identities. This improves codegen for (1LL << N).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19698 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/SelectionDAG/SelectionDAG.cpp')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 3da2f5fe7a..3b106d192d 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -615,6 +615,19 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT, std::swap(N1, N2); } } + + switch (Opcode) { + default: break; + case ISD::SHL: // shl 0, X -> 0 + if (N1C->isNullValue()) return N1; + break; + case ISD::SRL: // srl 0, X -> 0 + if (N1C->isNullValue()) return N1; + break; + case ISD::SRA: // sra -1, X -> -1 + if (N1C->isAllOnesValue()) return N1; + break; + } } if (N2C) { |