Find all backedges of CFG by MachineDominatorTree. please look at my jpg.

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Find all backedges of CFG by MachineDominatorTree. please look at my jpg.

 Hi: I hope to cut all backedges of MachineFunction CFG, then topological sort MachineBasicBlocks. 1. MachineDominatorTree *domintree = new MachineDominatorTree();    domintree->runOnMachineFunction(mf); 2. Then travel mf one by one.    When domintree->dominates(next,current) is true, there is a backedge from current node to next node. move this backedge form CFG.    But I find A LOOP in some CFG, there is backedge from current to next, dominates function reture "FALSE". So my algorithm find Graph can not be toplogical sort. 3. how do I find all backedges of CFG??? Thanks renkun       ___________________________________________________________   好玩贺卡等你发，邮箱贺卡全新上线！ http://card.mail.cn.yahoo.com/_______________________________________________ LLVM Developers mailing list [hidden email]         http://llvm.cs.uiuc.eduhttp://lists.cs.uiuc.edu/mailman/listinfo/llvmdev dominatorTree.jpg (95K) Download Attachment
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Re: Find all backedges of CFG by MachineDominatorTree. please look at my jpg.

 2010/1/25 任坤 <[hidden email]>: > Hi: > > I hope to cut all backedges of MachineFunction CFG, then topological sort MachineBasicBlocks. > > 1. MachineDominatorTree *domintree = new MachineDominatorTree(); >   domintree->runOnMachineFunction(mf); > > 2. Then travel mf one by one. >   When domintree->dominates(next,current) is true, there is a backedge from current node to next node. move this backedge form CFG. > >   But I find A LOOP in some CFG, there is backedge from current to next, dominates function reture "FALSE". So my algorithm find Graph can not be > toplogical sort. > > 3. how do I find all backedges of CFG??? For non-reducible graphs (as is the case for your example), it is no longer true that the target of a back-edge dominates the source. If you want back-edges, just do a depth-first search of the CFG, the back-edges are the edges going to an already processed node. If you want loop-edges (edges going to loop headers, that is more generic than back-edges), you'll need to build the loop nesting forest. Cheers, Benoit _______________________________________________ LLVM Developers mailing list [hidden email]         http://llvm.cs.uiuc.eduhttp://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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Re: Find all backedges of CFG by MachineDominatorTree. please look at my jpg.

 Dear Benoit:   Thanks for your answer. Best Regards. Ren Kun --- 10年1月25日，周一, Benoit Boissinot <[hidden email]> 写道： > 发件人: Benoit Boissinot <[hidden email]> > 主题: Re: [LLVMdev] Find all backedges of CFG by MachineDominatorTree.  please look at my jpg. > 收件人: "任坤" <[hidden email]> > 抄送: "llvm" <[hidden email]> > 日期: 2010年1月25日,周一,下午6:14 > 2010/1/25 任坤 <[hidden email]>: > > Hi: > > > > I hope to cut all backedges of MachineFunction CFG, > then topological sort MachineBasicBlocks. > > > > 1. MachineDominatorTree *domintree = new > MachineDominatorTree(); > >   domintree->runOnMachineFunction(mf); > > > > 2. Then travel mf one by one. > >   When > domintree->dominates(next,current) is true, there is a > backedge from current node to next node. move this backedge > form CFG. > > > >   But I find A LOOP in some CFG, there > is backedge from current to next, dominates function reture > "FALSE". So my algorithm find Graph can not be > > toplogical sort. > > > > 3. how do I find all backedges of CFG??? > > For non-reducible graphs (as is the case for your example), > it is no > longer true that the target of a back-edge dominates the > source. > > If you want back-edges, just do a depth-first search of the > CFG, the > back-edges are the edges going to an already processed > node. If you > want loop-edges (edges going to loop headers, that is more > generic > than back-edges), you'll need to build the loop nesting > forest. > > Cheers, > > Benoit >       ___________________________________________________________   好玩贺卡等你发，邮箱贺卡全新上线！ http://card.mail.cn.yahoo.com/_______________________________________________ LLVM Developers mailing list [hidden email]         http://llvm.cs.uiuc.eduhttp://lists.cs.uiuc.edu/mailman/listinfo/llvmdev