(if there are any) and use the one which remains available for the longest
rather than just using the first one. This should help enable better re-use
of the loaded frame index values. rdar://
7318760
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107847
91177308-0d34-0410-b5e6-
96231b3b80d8
/// getRegsUsed - return all registers currently in use in used.
void getRegsUsed(BitVector &used, bool includeReserved);
+ /// getRegsAvailable - Return all available registers in the register class
+ /// in Mask.
+ void getRegsAvailable(const TargetRegisterClass *RC, BitVector &Mask);
+
/// FindUnusedReg - Find a unused register of the specified register class.
/// Return 0 if none is found.
unsigned FindUnusedReg(const TargetRegisterClass *RegClass) const;
+ /// findSurvivorReg - Return the candidate register that is unused for the
+ /// longest after StartMI. UseMI is set to the instruction where the search
+ /// stopped.
+ ///
+ /// No more than InstrLimit instructions are inspected.
+ unsigned findSurvivorReg(MachineBasicBlock::iterator StartMI,
+ BitVector &Candidates,
+ unsigned InstrLimit,
+ MachineBasicBlock::iterator &UseMI);
+
/// setScavengingFrameIndex / getScavengingFrameIndex - accessor and setter of
/// ScavengingFrameIndex.
void setScavengingFrameIndex(int FI) { ScavengingFrameIndex = FI; }
/// Add Reg and its aliases to BV.
void addRegWithAliases(BitVector &BV, unsigned Reg);
- unsigned findSurvivorReg(MachineBasicBlock::iterator MI,
- BitVector &Candidates,
- unsigned InstrLimit,
- MachineBasicBlock::iterator &UseMI);
-
};
} // End llvm namespace
// Scavenge a new scratch register
CurrentVirtReg = Reg;
const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
- CurrentScratchReg = RS->FindUnusedReg(RC);
- if (CurrentScratchReg == 0)
+ const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
+ BitVector Candidates(TRI->getNumRegs());
+ RS->getRegsAvailable(RC, Candidates);
+
+ // If there are any registers available, use the one that's
+ // unused for the longest after this instruction. That increases
+ // the ability to reuse the value.
+ if (Candidates.any()) {
+ MachineBasicBlock::iterator UMI;
+ CurrentScratchReg = RS->findSurvivorReg(I, Candidates, 25, UMI);
+ } else {
// No register is "free". Scavenge a register.
CurrentScratchReg = RS->scavengeRegister(RC, I, SPAdj);
+ }
PrevValue = Value;
}
return 0;
}
+/// getRegsAvailable - Return all available registers in the register class
+/// in Mask.
+void RegScavenger::getRegsAvailable(const TargetRegisterClass *RC,
+ BitVector &Mask) {
+ for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
+ I != E; ++I)
+ if (!isAliasUsed(*I))
+ Mask.set(*I);
+}
+
/// findSurvivorReg - Return the candidate register that is unused for the
-/// longest after MBBI. UseMI is set to the instruction where the search
+/// longest after StargMII. UseMI is set to the instruction where the search
/// stopped.
///
/// No more than InstrLimit instructions are inspected.