search for: dominated

Hi Tobias, 1) Daniel and Chandler have for a long time been talking about computing > dominance and post-dominance in one shot to reduce the cost of > post-dominance and make it (freely) available everywhere. Is this > covered by your current (or planned) work? I'm not sure what you exactly mean by one shot; I'll ask around tomorrow. I wanted to play a little bit with your

...dominates(block(%b), block(%a)) and > DT->dominates(%b, %a). > > LLVM special cases "not reachable from entry", and says that no matter what, > #2 is true if %a is unreachable. > > The code is, IMHO, not even self-consistent > > > // Any unreachable use is dominated, even if Def == User. > if (!isReachableFromEntry(UseBB)) > return true; > > // Unreachable definitions don't dominate anything. > if (!isReachableFromEntry(DefBB)) > return false; > > > > Riddle me this: If unreachable definitions dominate nothi...

...ble length objects exist. On Wed, Nov 13, 2013 at 5:01 AM, Henrique Santos < henrique.nazare.santos at gmail.com> wrote: > It seems that placing the calls to free at the predecessors of dominance >> frontier is inadequate. It is possible that there are exit blocks that are >> dominated by BB12 (calls to malloc). I guess we can also insert calls to >> free at these exit blocks too. > > That crossed my mind a few minutes later. : ) > > If you're interested, PRE.cpp existed last at r25315. It calculates the > "availability frontier" which is probab...

...> On Wed, Nov 13, 2013 at 5:01 AM, Henrique Santos < > henrique.nazare.santos at gmail.com> wrote: > >> It seems that placing the calls to free at the predecessors of dominance >>> frontier is inadequate. It is possible that there are exit blocks that are >>> dominated by BB12 (calls to malloc). I guess we can also insert calls to >>> free at these exit blocks too. >> >> That crossed my mind a few minutes later. : ) >> >> If you're interested, PRE.cpp existed last at r25315. It calculates the >> "availability fronti...

...Dominates(llvm::DomTreeNodeBase<llvm::BasicBlock> const*, llvm::DomTreeNodeBase<llvm::BasicBlock> const*) const in: ../../lib/libLLVMAnalysis.a(PostDominators.cpp.o) ../../lib/libLLVMCore.a(Dominators.cpp.o) duplicate symbol llvm::DominatorTreeBase<llvm::BasicBlock, true>::dominatedBySlowTreeWalk(llvm::DomTreeNodeBase<llvm::BasicBlock> const*, llvm::DomTreeNodeBase<llvm::BasicBlock> const*) const in: ../../lib/libLLVMAnalysis.a(PostDominators.cpp.o) ../../lib/libLLVMCore.a(Dominators.cpp.o) duplicate symbol llvm::DominatorTreeBase<llvm::BasicBlock, true&...

Like I said, i'm nearly positive there is a much faster way, as the sets are mostly shared except in the cyclic case, and in all reducible cyclic cases, removal of back-arcs does not affect dominance (because in any reducible flowgraph, v dominates u whenever u,v is a back-arc) On Tue, Apr 25, 2017 at 7:38 PM, Hongbin Zheng <etherzhhb at gmail.com> wrote: > Hi Daniel, > >

Hi Daniel, Thanks a lot for all these explanation, I will try it out. Hongbin On Tue, Apr 25, 2017 at 7:04 PM, Daniel Berlin <dberlin at dberlin.org> wrote: > > > On Tue, Apr 25, 2017 at 6:42 PM, Hongbin Zheng <etherzhhb at gmail.com> > wrote: > >> >> >> On Tue, Apr 25, 2017 at 6:32 PM, Daniel Berlin <dberlin at dberlin.org> >> wrote:

...ge from START to END). In contrast, it seems that the current LLVM post-dominator analysis only operates in a mode in which it generates a forest of post-dominator trees, with one rooted at each exit node. The problem this can cause is that, by nature, these trees omit some nodes which are not post-dominated by any one exit. This invalidates analyses which build on a traversal of the post-dominator tree. (In my case, I'm implementing Pingali & Bilardi's optimal control dependence algorithms: http://doi.acm.org/10.1145/256167.256217.) Consider, for example, a simple function with a single...

When looking into https://llvm.org/bugs/show_bug.cgi?id=24866, I discovered that the root cause of the crash is that I was expecting every basic block to have a corresponding Node in the dominator tree. Apparently, the "while.end" basic block in the example does not have a Node in the Dominator Tree. Can anyone tell me if this is expected? If so, under what circumstances?

Hi, In browsing through the LLVM source, I don't currently see an implementation for a control dependence graph builder. Am I overlooking something? It doesn't look like LLVM currently provides a way to build the post-dominance frontier of the reverse CFG, either. Dominators.h mentions forward dominators, but I believe all this is referring to is dominators as opposed to post-dominators,

On 25 February 2015 at 10:58, Daniel Berlin <dberlin at dberlin.org> wrote: > > > On Wed, Feb 25, 2015 at 6:26 AM, Rafael Espíndola > <rafael.espindola at gmail.com> wrote: >> >> > Maybe. >> > My view is the ideal is either no-unreachable code, or unreachable >> > blocks >> > only contain terminators. >> >> I am

Btw, here is another interesting paper about post-dominators and control dependence: https://pdfs.semanticscholar.org/cbb2/9a0e4895025bd9df24f9263217df12f1ed1e.pdf I think a great outcome of your internship would be some precise documentation regarding the guarantees the LLVM dominators give -- possibly also considering classic and weak control dependence and the difference between

Hi I run into an issue as part of splitting a critical edge during LICM. When a new basic block is created and needs to be added into the dominator tree, the block is already in the dominator tree. I print the dominator tree and I see it is added into the tree as child of node it is supposed to dominate. How do I debug to find out why/when its getting added into the tree. ? Tips/suggestions on

There is PostDominatorTree for determining post-dominance. Even if A post-dominates B and B is executed, that doesn't guarantee that A will be executed. For example, there could be an infinite loop in-between. Strong post-dominance makes the stronger guarantee that there will be no infinite loop from B to A. Do we have anything in LLVM for determining strong post-dominance and in general for

On Tue, Apr 25, 2017 at 6:32 PM, Daniel Berlin <dberlin at dberlin.org> wrote: > > > On Tue, Apr 25, 2017 at 6:17 PM, Hongbin Zheng <etherzhhb at gmail.com> > wrote: > >> Hi Daniel, >> >> I mean "*As a set*, B + C dominate D". >> >> On Tue, Apr 25, 2017 at 5:42 PM, Daniel Berlin <dberlin at dberlin.org> >> wrote:

...013 at 9:13 PM, Henrique Santos < henrique.nazare.santos at gmail.com> wrote: > PRE normally uses a latest placement algorithm to do something of the sort. > I don't know about GVN/PRE, but older version of PRE might have it. > Just placing the calls to free at the predecessors (dominated by BB12) of > the dominance frontier of BB12 seems to work, however. Is there anything > wrong with this? > It seems that placing the calls to free at the predecessors of dominance frontier is inadequate. It is possible that there are exit blocks that are dominated by BB12 (calls to malloc...

> > It seems that placing the calls to free at the predecessors of dominance > frontier is inadequate. It is possible that there are exit blocks that are > dominated by BB12 (calls to malloc). I guess we can also insert calls to > free at these exit blocks too. That crossed my mind a few minutes later. : ) If you're interested, PRE.cpp existed last at r25315. It calculates the "availability frontier" which is probably what you're looking...

Hi, Is there any way to quickly test if a set of basic block collectively dominate another basic block? Thanks Hongbin -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170425/b9336a6d/attachment.html>

Hi folks, This summer I'm working on improving dominators during my internship at Google. Below is an RFC on switching to dynamic dominators, which you can also read as a Google Doc <https://docs.google.com/document/d/1wPYeWykeO51YDPLYQEg4KNTlDIGIdyF65OTfhSMaNHQ/edit?usp=sharing> if you prefer so. Please let us know what you think. ~Kuba

...). In contrast, it > seems that the current LLVM post-dominator analysis only operates in a > mode in which it generates a forest of post-dominator trees, with one > rooted at each exit node. The problem this can cause is that, by > nature, these trees omit some nodes which are not post-dominated by > any one exit. This invalidates analyses which build on a traversal of > the post-dominator tree. > > (In my case, I'm implementing Pingali & Bilardi's optimal control > dependence algorithms: http://doi.acm.org/10.1145/256167.256217.) > > Consider, for example,...