#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachinePostDominators.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
class MachineSinking : public MachineFunctionPass {
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
- MachineRegisterInfo *MRI; // Machine register information
- MachineDominatorTree *DT; // Machine dominator tree
+ MachineRegisterInfo *MRI; // Machine register information
+ MachineDominatorTree *DT; // Machine dominator tree
+ MachinePostDominatorTree *PDT; // Machine post dominator tree
MachineLoopInfo *LI;
AliasAnalysis *AA;
MachineFunctionPass::getAnalysisUsage(AU);
AU.addRequired<AliasAnalysis>();
AU.addRequired<MachineDominatorTree>();
+ AU.addRequired<MachinePostDominatorTree>();
AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineDominatorTree>();
+ AU.addPreserved<MachinePostDominatorTree>();
AU.addPreserved<MachineLoopInfo>();
}
TRI = TM.getSubtargetImpl()->getRegisterInfo();
MRI = &MF.getRegInfo();
DT = &getAnalysis<MachineDominatorTree>();
+ PDT = &getAnalysis<MachinePostDominatorTree>();
LI = &getAnalysis<MachineLoopInfo>();
AA = &getAnalysis<AliasAnalysis>();
}
}
-/// isPostDominatedBy - Return true if A is post dominated by B.
-static bool isPostDominatedBy(MachineBasicBlock *A, MachineBasicBlock *B) {
-
- // FIXME - Use real post dominator.
- if (A->succ_size() != 2)
- return false;
- MachineBasicBlock::succ_iterator I = A->succ_begin();
- if (B == *I)
- ++I;
- MachineBasicBlock *OtherSuccBlock = *I;
- if (OtherSuccBlock->succ_size() != 1 ||
- *(OtherSuccBlock->succ_begin()) != B)
- return false;
-
- return true;
-}
-
/// isProfitableToSinkTo - Return true if it is profitable to sink MI.
bool MachineSinking::isProfitableToSinkTo(unsigned Reg, MachineInstr *MI,
MachineBasicBlock *MBB,
return false;
// It is profitable if SuccToSinkTo does not post dominate current block.
- if (!isPostDominatedBy(MBB, SuccToSinkTo))
- return true;
+ if (!PDT->dominates(SuccToSinkTo, MBB))
+ return true;
// Check if only use in post dominated block is PHI instruction.
bool NonPHIUse = false;
++MachineBasicBlock::iterator(DbgMI));
}
- // Conservatively, clear any kill flags, since it's possible that they are no
- // longer correct.
- MI->clearKillInfo();
+ // When sinking the instruction the live time of its operands can be extended
+ // bejond their original last use (marked with a kill flag). Conservatively
+ // clear the kill flag in all instructions that use the same operand
+ // registers.
+ for (auto &MO : MI->uses())
+ if (MO.isReg() && MO.isUse()) {
+ // Preserve the kill flag for this instruction.
+ bool IsKill = MO.isKill();
+ // Clear the kill flag in all instruction that use this operand.
+ MRI->clearKillFlags(MO.getReg());
+ // Restore the kill flag for only this instruction.
+ MO.setIsKill(IsKill);
+ }
return true;
}