diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/CodeGen/TwoAddressInstructionPass.cpp | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp index e0dba3f..e312642 100644 --- a/lib/CodeGen/TwoAddressInstructionPass.cpp +++ b/lib/CodeGen/TwoAddressInstructionPass.cpp @@ -372,12 +372,19 @@ static bool isPlainlyKilled(MachineInstr *MI, unsigned Reg, /// normal heuristics commute the (two-address) add, which lets /// coalescing eliminate the extra copy. /// +/// If allowFalsePositives is true then likely kills are treated as kills even +/// if it can't be proven that they are kills. static bool isKilled(MachineInstr &MI, unsigned Reg, const MachineRegisterInfo *MRI, const TargetInstrInfo *TII, - LiveIntervals *LIS) { + LiveIntervals *LIS, + bool allowFalsePositives) { MachineInstr *DefMI = &MI; for (;;) { + // All uses of physical registers are likely to be kills. + if (TargetRegisterInfo::isPhysicalRegister(Reg) && + (allowFalsePositives || MRI->hasOneUse(Reg))) + return true; if (!isPlainlyKilled(DefMI, Reg, LIS)) return false; if (TargetRegisterInfo::isPhysicalRegister(Reg)) @@ -1028,7 +1035,7 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, assert(TargetRegisterInfo::isVirtualRegister(regB) && "cannot make instruction into two-address form"); - bool regBKilled = isKilled(MI, regB, MRI, TII, LIS); + bool regBKilled = isKilled(MI, regB, MRI, TII, LIS, true); if (TargetRegisterInfo::isVirtualRegister(regA)) scanUses(regA); @@ -1048,7 +1055,7 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, if (regCIdx != ~0U) { regC = MI.getOperand(regCIdx).getReg(); - if (!regBKilled && isKilled(MI, regC, MRI, TII, LIS)) + if (!regBKilled && isKilled(MI, regC, MRI, TII, LIS, false)) // If C dies but B does not, swap the B and C operands. // This makes the live ranges of A and C joinable. TryCommute = true; |