search for: isctrl

...nt to use the patch [1] I sent before as an example. Could someone give me advice/guideline here? Also, I have another question. Sometimes the for-loop uses const_iterator, say for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); I != E; ++I) if (I->isCtrl()) NumberDeps++; Can we rewrite above code as, for (auto &Succ : SU->Succs) if (Succ.isCtrl()) NumberDeps++; Or do we need to use `const auto &` instead, like this for ( ​const ​ auto &Succ : SU->Succs) if (Succ.isCtrl()) NumberDeps++; Thank...

Hello again, Sorry -- I think I found the problem somewhere else. I was a bit confused and missed the fact that adjustChainDeps() is called a few lines down and does just what I wanted :-) I would like to instead ask another question: Why is I->isCtrl() used in code like // Iterate over chain dependencies only. for (SUnit::const_succ_iterator I = SUb->Succs.begin(), E = SUb->Succs.end(); I != E; ++I) if (I->isCtrl()) iterateChainSucc (AA, MFI, SUa, I->getSUnit(), ExitSU, Depth, Visited); ? I thought only chain edges are...

Hi, Thank you for the reply. >It looks to me like we can choose any subset of edges here and be correct. We're basically trying to prune/pinch the DAG edges here. They can easily blow up with AA sched. I would guess that isCtrl() edges are good ones to bypass because they could be a low-latecy edges, whereas true data dependencies from a load are expected to be >higher latency, so they are good candidates to stop the search. I cannot say I understand your answer, unfortunately, and to clarify all this eventually, I wi...

...1. Is it too aggressive in searching predecessors and successors? Should the algorithm give up and assume the worst if the depth of search reaches a predefined limit? 2. Should the initial search for 'SetUp1' and 'Destroy1' only search along chains? viz conditional upon II->isCtrl() 3. Is it possible to input a DAG for testing? What is the best way to construct the test case? Using an IR as input does not guarantee the required DAG will be output for testing. 4. Where should the test be placed? (How do I test for no-assert?) Please do comment. Robert -------...

...e in searching predecessors and successors? > Should the algorithm give up and assume the worst if the depth of > search reaches a predefined limit? > > 2. Should the initial search for 'SetUp1' and 'Destroy1' only search along > chains? viz conditional upon II->isCtrl() > The code is a kludge to work around a particular symptom of a deeper bug in the underlying scheduling algorithm. It's entirely possible that you've found a real bug in it; feel free to check in the fix if you're confident it's right. > 3. Is it possible to input a DAG f...

Hi, Can anyone help me to understand the ScheduleDAGInstrs::buildSchedGraph() method? I find the handling of AliasChain is disturbing since: 1. A new alias chain add deps to all possibly aliasing SUs, and then clears those lists. 2. When AliasChain is present, the addChainDependency() method is called, but the target hook areMemAccessesTriviallyDisjoint() called inside

sorry, Just noticed that the diagrams have 'Destroy' & 'SetUp' the wrong way around! Robert ________________________________ From: llvmdev-bounces at cs.uiuc.edu [llvmdev-bounces at cs.uiuc.edu] on behalf of Robert Lytton [robert at xmos.com] Sent: 21 August 2013 18:34 To: llvmdev at cs.uiuc.edu Subject: Re: [LLVMdev] PrescheduleNodesWithMultipleUses() causing failure in

Hi, I have reasoned through and believe the problem is with the PrescheduleNodesWithMultipleUses. Take the following DAG (arrow to predecessor): Destroy Destroy ^ ^ | | | | SetUp----->PredSU <-----SU ^ ^ ^ | | | | | | ----------- |