call dependencies between BranchFolder::replaceTailWithBranchTo and BranchFolder::mergeCommonTails

[• pbrunet]

Summary

Both functions use LiveRegs but init is only done in mergeCommonTails. It creates a dependency between this function while an init instead of clear in replaceTailWithBranchTo would do the job.

Also, if MBB->predecessors is empty (I don't know if it is possible), the initialization would not be done.

[• pbrunet]

Update line numbers as previous diff was on an old branch.

lib/CodeGen/BranchFolding.cpp

   if (UpdateLiveIns) {
     // OldInst should always point to an instruction.
     MachineBasicBlock &OldMBB = *OldInst->getParent();
-    LiveRegs.clear();
+    LiveRegs.init(*TRI);
     LiveRegs.addLiveOuts(OldMBB);
     // Move backward to the place where will insert the jump.
     MachineBasicBlock::iterator I = OldMBB.end();