diff options
| -rw-r--r-- | llvm/lib/CodeGen/RegisterCoalescer.cpp | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp index 5d958a61e6a..a8fcd950268 100644 --- a/llvm/lib/CodeGen/RegisterCoalescer.cpp +++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp @@ -194,7 +194,7 @@ namespace { /// If the source of a copy is defined by a /// trivial computation, replace the copy by rematerialize the definition. - bool reMaterializeTrivialDef(CoalescerPair &CP, MachineInstr *CopyMI, + bool reMaterializeTrivialDef(const CoalescerPair &CP, MachineInstr *CopyMI, bool &IsDefCopy); /// Return true if a copy involving a physreg should be joined. @@ -851,7 +851,7 @@ static bool definesFullReg(const MachineInstr &MI, unsigned Reg) { return false; } -bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP, +bool RegisterCoalescer::reMaterializeTrivialDef(const CoalescerPair &CP, MachineInstr *CopyMI, bool &IsDefCopy) { IsDefCopy = false; @@ -929,6 +929,29 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP, TII->reMaterialize(*MBB, MII, DstReg, SrcIdx, DefMI, *TRI); MachineInstr *NewMI = std::prev(MII); + // A situation like the following: + // %vreg0:subX = instr ; DefMI + // %vregY = copy %vreg:subX ; CopyMI + // does not need subregisters/regclass widening after rematerialization, just + // do: + // %vregY = instr + const TargetRegisterClass *NewRC = CP.getNewRC(); + if (DstIdx != 0) { + MachineOperand &DefMO = NewMI->getOperand(0); + if (DefMO.getSubReg() == DstIdx) { + assert(SrcIdx == 0 && CP.isFlipped() + && "Shouldn't have SrcIdx+DstIdx at this point"); + const TargetRegisterClass *DstRC = MRI->getRegClass(DstReg); + const TargetRegisterClass *CommonRC = + TRI->getCommonSubClass(DefRC, DstRC); + if (CommonRC != nullptr) { + NewRC = CommonRC; + DstIdx = 0; + DefMO.setSubReg(0); + } + } + } + LIS->ReplaceMachineInstrInMaps(CopyMI, NewMI); CopyMI->eraseFromParent(); ErasedInstrs.insert(CopyMI); @@ -948,7 +971,6 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP, } if (TargetRegisterInfo::isVirtualRegister(DstReg)) { - const TargetRegisterClass *NewRC = CP.getNewRC(); unsigned NewIdx = NewMI->getOperand(0).getSubReg(); if (DefRC != nullptr) { |
