diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index a9b7f66..0d37c62 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -1903,8 +1903,6 @@ bool SelectionDAGBuilder::handleSmallSwitchRange(CaseRec& CR, const Value* SV, MachineBasicBlock *Default, MachineBasicBlock *SwitchBB) { - Case& BackCase = *(CR.Range.second-1); - // Size is the number of Cases represented by this range. size_t Size = CR.Range.second - CR.Range.first; if (Size > 3) @@ -1972,11 +1970,28 @@ bool SelectionDAGBuilder::handleSmallSwitchRange(CaseRec& CR, } } + // Order cases by weight so the most likely case will be checked first. + BranchProbabilityInfo *BPI = FuncInfo.BPI; + if (BPI) { + for (CaseItr I = CR.Range.first, IE = CR.Range.second; I != IE; ++I) { + uint32_t IWeight = BPI->getEdgeWeight(SwitchBB->getBasicBlock(), + I->BB->getBasicBlock()); + for (CaseItr J = CR.Range.first; J < I; ++J) { + uint32_t JWeight = BPI->getEdgeWeight(SwitchBB->getBasicBlock(), + J->BB->getBasicBlock()); + if (IWeight > JWeight) + std::swap(*I, *J); + } + } + } + // Rearrange the case blocks so that the last one falls through if possible. + Case &BackCase = *(CR.Range.second-1); if (NextBlock && Default != NextBlock && BackCase.BB != 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 (CaseItr I = CR.Range.first, E = CR.Range.second-1; I != E; ++I) { + // We start at the bottom as it's the case with the least weight. + for (CaseItr I = CR.Range.second-2, E = CR.Range.first-1; I != E; --I) { if (I->BB == NextBlock) { std::swap(*I, BackCase); break; |