diff options
| -rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp index 9786d2b3e9..fa4407def5 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp @@ -936,6 +936,19 @@ void SelectionDAGLowering::visitSwitch(SwitchInst &I) { // use bit manipulation to do two compares at once. For example: // "if (X == 6 || X == 4)" -> "if ((X|2) == 6)" + // Rearrange the case blocks so that the last one falls through if possible. + if (NextBlock && Default != NextBlock && Cases.back().second != NextBlock) { + // The last case block won't fall through into 'NextBlock' if we emit the + // branches in this order. See if rearranging a case value would help. + for (unsigned i = 0, e = Cases.size()-1; i != e; ++i) { + if (Cases[i].second == NextBlock) { + std::swap(Cases[i], Cases.back()); + break; + } + } + } + + // Create a CaseBlock record representing a conditional branch to // the Case's target mbb if the value being switched on SV is equal // to C. |