diff options
Diffstat (limited to 'lib/CodeGen/MachineBasicBlock.cpp')
| -rw-r--r-- | lib/CodeGen/MachineBasicBlock.cpp | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp index 18d021d521..4406c89aba 100644 --- a/lib/CodeGen/MachineBasicBlock.cpp +++ b/lib/CodeGen/MachineBasicBlock.cpp @@ -982,7 +982,6 @@ MachineBasicBlock::LivenessQueryResult MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI, unsigned Reg, MachineInstr *MI, unsigned Neighborhood) { - unsigned N = Neighborhood; MachineBasicBlock *MBB = MI->getParent(); @@ -997,14 +996,18 @@ MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI, MachineOperandIteratorBase::PhysRegInfo Analysis = MIOperands(I).analyzePhysReg(Reg, TRI); - if (Analysis.Kills) + if (Analysis.Defines) + // Outputs happen after inputs so they take precedence if both are + // present. + return Analysis.DefinesDead ? LQR_Dead : LQR_Live; + + if (Analysis.Kills || Analysis.Clobbers) // Register killed, so isn't live. return LQR_Dead; - else if (Analysis.DefinesOverlap || Analysis.ReadsOverlap) + else if (Analysis.ReadsOverlap) // Defined or read without a previous kill - live. - return (Analysis.Defines || Analysis.Reads) ? - LQR_Live : LQR_OverlappingLive; + return Analysis.Reads ? LQR_Live : LQR_OverlappingLive; } while (I != MBB->begin() && --N > 0); } @@ -1036,7 +1039,7 @@ MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI, return (Analysis.Reads) ? LQR_Live : LQR_OverlappingLive; - else if (Analysis.DefinesOverlap) + else if (Analysis.Clobbers || Analysis.Defines) // Defined (but not read) therefore cannot have been live. return LQR_Dead; } |