diff options
| -rw-r--r-- | llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp b/llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp index 5d5a5689d0e..79b78abe95a 100644 --- a/llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp +++ b/llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp @@ -178,6 +178,17 @@ uint64_t RegBankSelect::getRepairCost( // the repairing. if (MO.isDef()) std::swap(CurRegBank, DesiredRegBrank); + // TODO: It may be possible to actually avoid the copy. + // If we repair something where the source is defined by a copy + // and the source of that copy is on the right bank, we can reuse + // it for free. + // E.g., + // RegToRepair<BankA> = copy AlternativeSrc<BankB> + // = op RegToRepair<BankA> + // We can simply propagate AlternativeSrc instead of copying RegToRepair + // into a new virtual register. + // We would also need to propagate this information in the + // repairing placement. unsigned Cost = RBI->copyCost(*DesiredRegBrank, *CurRegBank, RegisterBankInfo::getSizeInBits(MO.getReg(), *MRI, *TRI)); |
