diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp')
-rw-r--r-- | contrib/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp | 54 |
1 files changed, 16 insertions, 38 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp b/contrib/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp index d6206a3..92ce500 100644 --- a/contrib/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp +++ b/contrib/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp @@ -193,44 +193,22 @@ BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, // If there are any PHI nodes in DestBB, we need to update them so that they // merge incoming values from NewBB instead of from TIBB. - if (PHINode *APHI = dyn_cast<PHINode>(DestBB->begin())) { - // This conceptually does: - // foreach (PHINode *PN in DestBB) - // PN->setIncomingBlock(PN->getIncomingBlock(TIBB), NewBB); - // but is optimized for two cases. - - if (APHI->getNumIncomingValues() <= 8) { // Small # preds case. - unsigned BBIdx = 0; - for (BasicBlock::iterator I = DestBB->begin(); isa<PHINode>(I); ++I) { - // We no longer enter through TIBB, now we come in through NewBB. - // Revector exactly one entry in the PHI node that used to come from - // TIBB to come from NewBB. - PHINode *PN = cast<PHINode>(I); - - // Reuse the previous value of BBIdx if it lines up. In cases where we - // have multiple phi nodes with *lots* of predecessors, this is a speed - // win because we don't have to scan the PHI looking for TIBB. This - // happens because the BB list of PHI nodes are usually in the same - // order. - if (PN->getIncomingBlock(BBIdx) != TIBB) - BBIdx = PN->getBasicBlockIndex(TIBB); - PN->setIncomingBlock(BBIdx, NewBB); - } - } else { - // However, the foreach loop is slow for blocks with lots of predecessors - // because PHINode::getIncomingBlock is O(n) in # preds. Instead, walk - // the user list of TIBB to find the PHI nodes. - SmallPtrSet<PHINode*, 16> UpdatedPHIs; - - for (Value::use_iterator UI = TIBB->use_begin(), E = TIBB->use_end(); - UI != E; ) { - Value::use_iterator Use = UI++; - if (PHINode *PN = dyn_cast<PHINode>(*Use)) { - // Remove one entry from each PHI. - if (PN->getParent() == DestBB && UpdatedPHIs.insert(PN)) - PN->setOperand(Use.getOperandNo(), NewBB); - } - } + { + unsigned BBIdx = 0; + for (BasicBlock::iterator I = DestBB->begin(); isa<PHINode>(I); ++I) { + // We no longer enter through TIBB, now we come in through NewBB. + // Revector exactly one entry in the PHI node that used to come from + // TIBB to come from NewBB. + PHINode *PN = cast<PHINode>(I); + + // Reuse the previous value of BBIdx if it lines up. In cases where we + // have multiple phi nodes with *lots* of predecessors, this is a speed + // win because we don't have to scan the PHI looking for TIBB. This + // happens because the BB list of PHI nodes are usually in the same + // order. + if (PN->getIncomingBlock(BBIdx) != TIBB) + BBIdx = PN->getBasicBlockIndex(TIBB); + PN->setIncomingBlock(BBIdx, NewBB); } } |