if (SwitchMBB + 1 != FuncInfo.MF->end())
NextBlock = SwitchMBB + 1;
-
- // Create a vector of Cases, sorted so that we can efficiently create a binary
- // search tree from them.
- CaseVector Cases;
- Clusterify(Cases, SI);
-
- // Get the default destination MBB.
MachineBasicBlock *Default = FuncInfo.MBBMap[SI.getDefaultDest()];
- if (isa<UnreachableInst>(SI.getDefaultDest()->getFirstNonPHIOrDbg())) {
- // Replace an unreachable default destination with the most popular case
- // destination.
- DenseMap<const BasicBlock*, uint64_t> Popularity;
- uint64_t MaxPop = 0;
- const BasicBlock *MaxBB = nullptr;
- for (auto I : SI.cases()) {
- const BasicBlock *BB = I.getCaseSuccessor();
- if (++Popularity[BB] > MaxPop) {
- MaxPop = Popularity[BB];
- MaxBB = BB;
- }
- }
-
- // Set new default.
- Default = FuncInfo.MBBMap[MaxBB];
-
- // Remove cases that have been replaced by the default.
- CaseItr I = Cases.begin();
- while (I != Cases.end()) {
- if (I->BB == Default) {
- I = Cases.erase(I);
- continue;
- }
- ++I;
- }
- }
-
- // If there is only the default destination, go there directly.
- if (Cases.empty()) {
+ // If there is only the default destination, branch to it if it is not the
+ // next basic block. Otherwise, just fall through.
+ if (!SI.getNumCases()) {
// Update machine-CFG edges.
SwitchMBB->addSuccessor(Default);
// If this is not a fall-through branch, emit the branch.
- if (Default != NextBlock) {
- DAG.setRoot(DAG.getNode(ISD::BR, getCurSDLoc(), MVT::Other,
- getControlRoot(), DAG.getBasicBlock(Default)));
- }
+ if (Default != NextBlock)
+ DAG.setRoot(DAG.getNode(ISD::BR, getCurSDLoc(),
+ MVT::Other, getControlRoot(),
+ DAG.getBasicBlock(Default)));
+
return;
}
- // Get the Value to be switched on.
+ // If there are any non-default case statements, create a vector of Cases
+ // representing each one, and sort the vector so that we can efficiently
+ // create a binary search tree from them.
+ CaseVector Cases;
+ Clusterify(Cases, SI);
+
+ // Get the Value to be switched on and default basic blocks, which will be
+ // inserted into CaseBlock records, representing basic blocks in the binary
+ // search tree.
const Value *SV = SI.getCondition();
// Push the initial CaseRec onto the worklist