diff options
Diffstat (limited to 'lib/CodeGen/BranchFolding.cpp')
| -rw-r--r-- | lib/CodeGen/BranchFolding.cpp | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp index 23e2aa70d0c7..5dacbf9e6b02 100644 --- a/lib/CodeGen/BranchFolding.cpp +++ b/lib/CodeGen/BranchFolding.cpp @@ -776,9 +776,8 @@ bool BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB, } static void -mergeMMOsFromMemoryOperations(MachineBasicBlock::iterator MBBIStartPos, - MachineBasicBlock &MBBCommon) { - // Merge MMOs from memory operations in the common block. +mergeOperations(MachineBasicBlock::iterator MBBIStartPos, + MachineBasicBlock &MBBCommon) { MachineBasicBlock *MBB = MBBIStartPos->getParent(); // Note CommonTailLen does not necessarily matches the size of // the common BB nor all its instructions because of debug @@ -808,8 +807,18 @@ mergeMMOsFromMemoryOperations(MachineBasicBlock::iterator MBBIStartPos, "Reached BB end within common tail length!"); assert(MBBICommon->isIdenticalTo(*MBBI) && "Expected matching MIIs!"); + // Merge MMOs from memory operations in the common block. if (MBBICommon->mayLoad() || MBBICommon->mayStore()) MBBICommon->setMemRefs(MBBICommon->mergeMemRefsWith(*MBBI)); + // Drop undef flags if they aren't present in all merged instructions. + for (unsigned I = 0, E = MBBICommon->getNumOperands(); I != E; ++I) { + MachineOperand &MO = MBBICommon->getOperand(I); + if (MO.isReg() && MO.isUndef()) { + const MachineOperand &OtherMO = MBBI->getOperand(I); + if (!OtherMO.isUndef()) + MO.setIsUndef(false); + } + } ++MBBI; ++MBBICommon; @@ -928,8 +937,8 @@ bool BranchFolder::TryTailMergeBlocks(MachineBasicBlock *SuccBB, continue; DEBUG(dbgs() << "BB#" << SameTails[i].getBlock()->getNumber() << (i == e-1 ? "" : ", ")); - // Merge MMOs from memory operations as needed. - mergeMMOsFromMemoryOperations(SameTails[i].getTailStartPos(), *MBB); + // Merge operations (MMOs, undef flags) + mergeOperations(SameTails[i].getTailStartPos(), *MBB); // Hack the end off BB i, making it jump to BB commonTailIndex instead. ReplaceTailWithBranchTo(SameTails[i].getTailStartPos(), MBB); // BB i is no longer a predecessor of SuccBB; remove it from the worklist. |