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Teach EmitLiveInCopies to omit copies for unused virtual registers,
and to clean up unused incoming physregs from the live-in list. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106805 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -182,21 +182,32 @@ MachineRegisterInfo::EmitLiveInCopies(MachineBasicBlock *EntryMBB,
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const TargetRegisterInfo &TRI,
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const TargetInstrInfo &TII) {
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// Emit the copies into the top of the block.
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for (MachineRegisterInfo::livein_iterator LI = livein_begin(),
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E = livein_end(); LI != E; ++LI)
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if (LI->second) {
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const TargetRegisterClass *RC = getRegClass(LI->second);
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bool Emitted = TII.copyRegToReg(*EntryMBB, EntryMBB->begin(),
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LI->second, LI->first, RC, RC,
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DebugLoc());
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assert(Emitted && "Unable to issue a live-in copy instruction!\n");
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(void) Emitted;
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}
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for (unsigned i = 0, e = LiveIns.size(); i != e; ++i)
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if (LiveIns[i].second) {
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if (use_empty(LiveIns[i].second)) {
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// The livein has no uses. Drop it.
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//
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// It would be preferable to have isel avoid creating live-in
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// records for unused arguments in the first place, but it's
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// complicated by the debug info code for arguments.
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LiveIns.erase(LiveIns.begin() + i);
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--i; --e;
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} else {
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// Emit a copy.
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const TargetRegisterClass *RC = getRegClass(LiveIns[i].second);
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bool Emitted = TII.copyRegToReg(*EntryMBB, EntryMBB->begin(),
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LiveIns[i].second, LiveIns[i].first,
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RC, RC, DebugLoc());
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assert(Emitted && "Unable to issue a live-in copy instruction!\n");
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(void) Emitted;
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// Add function live-ins to entry block live-in set.
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for (MachineRegisterInfo::livein_iterator I = livein_begin(),
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E = livein_end(); I != E; ++I)
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EntryMBB->addLiveIn(I->first);
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// Add the register to the entry block live-in set.
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EntryMBB->addLiveIn(LiveIns[i].first);
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}
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} else {
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// Add the register to the entry block live-in set.
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EntryMBB->addLiveIn(LiveIns[i].first);
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}
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}
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void MachineRegisterInfo::closePhysRegsUsed(const TargetRegisterInfo &TRI) {
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