similar to: [LLVMdev] LoopSimplify : why to separate a loop with multiple backedges into a nested loop ?

I will try to reduce a test case for the regression I found and will update. Thanks, Balaram From: Friedman, Eli [mailto:efriedma at codeaurora.org] Sent: Friday, June 30, 2017 2:54 PM To: Balaram Makam <bmakam at codeaurora.org>; llvm-dev at lists.llvm.org Subject: Re: [llvm-dev] LoopSimplify pass prevents loop unrolling On 6/30/2017 11:38 AM, Balaram Makam wrote: Thanks Eli,

On 6/30/2017 11:38 AM, Balaram Makam wrote: > > Thanks Eli, > > I was looking at this code which keeps track of loop headers but is > checking if the destination of branch is a loop header sufficient? > This prevents merging empty preheaders into the loop headers as well. > There isn't really any reason to collapse preheaders anyway; LoopSimplify will recreate them,

On 6/30/2017 7:48 AM, Balaram Makam via llvm-dev wrote: > > Edit. Predecessor -> successor. > > *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] *On Behalf > Of *Balaram Makam via llvm-dev > *Sent:* Friday, June 30, 2017 10:47 AM > *To:* llvm-dev at lists.llvm.org > *Subject:* [llvm-dev] LoopSimplify pass prevents loop unrolling > > Hi All, > >

Hi All, In the attached test case there, is an unnested loop with 2 iterations. The loop latch block is terminated by an unconditional branch, so simplifycfg folds the almost empty latch block into its predecessor which is the loop header. This results in an additional backedge in the CFG, so when LoopRotate pass is called it canonicalizes the loop into a nested loop. However, now the loop

I am trying to add an analysis pass as a FunctionPass, and let LICM (LoopPass) depends upon it. So in LICM.cpp, I have the following: virtual void getAnalysisUsage(AnalysisUsage &AU) const { AU.setPreservesCFG(); AU.addRequired<DominatorTree>(); AU.addRequired<LoopInfo>(); AU.addRequiredID(LoopSimplifyID); AU.addRequired<AliasAnalysis>();

Hi Chris, Thanks. I will see what I can do for this. Junjie On Wed, May 19, 2010 at 3:45 PM, Chris Lattner <clattner at apple.com> wrote: > > On May 19, 2010, at 2:38 PM, Junjie Gu wrote: > >> Many compilers support per-loop pragma, such as loop unrolling (ie >> #pragma unroll=2).  Is there any LLVM project/effort going on >> in this area ? What is the expected

I'd like to add a pragma support in llvm. I am thinking about using a llvm intrinsic to represent each pragma, such as llvm.pragma (metadata, ...) where metadata describes a pragma. So if an application has: #pragma p1 .. #pragma p2... for (...) The llvm IR would be llvm.pragma (metadata..) // for p1 llvm.pragma (metadata..) // for p2 llvm IR for "for

Hi all, I would like to propose an improvement of the “almost dead” block elimination in Transforms/Local.cpp so that it will preserve the canonical loop form for loops with a volatile iteration variable. *** Problem statement Nested loops in LCALS Subset B (https://codesign.llnl.gov/LCALS.php) are not vectorized with LLVM -O3 because the LLVM loop vectorizer fails the test whether the loop

Thanks for comments/suggestions. Yes, attaching metadata to instructions will be good choices for many cases. But for loops, attaching metadata to back-edges requires that the front end to build loops, which is an additional task for the front end. And this task is really a backend's job, not the front end's. If the only concern is that it is hard for pragma intrinsics to stay with their

On Tue, Jun 1, 2010 at 5:42 PM, Junjie Gu <jgu222 at gmail.com> wrote: > Any suggestions/ideas ? IIUC, Chris suggested something like following ... header: br i1 %x, label %then, %label endif then: ... br i1 %y, label %loop_exit, label %header, !loop_pragma !1 endif: ... br i1 %z, label %loop_exit, label %header, !loop_pragma !2 loop_exit: ret i32 1 Where !1 and !2 are the

On May 19, 2010, at 2:38 PM, Junjie Gu wrote: > Many compilers support per-loop pragma, such as loop unrolling (ie > #pragma unroll=2). Is there any LLVM project/effort going on > in this area ? What is the expected way for implementing per-loop > pragma, or general pragma ? Suggestions/comments ? Hi Junjie, I don't know of anyone working on it, but it seems like a natural

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

2010/1/25 任坤 <hbrenkun at yahoo.cn>: > 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

On Wed, Sep 28, 2011 at 5:47 PM, Eli Friedman <eli.friedman at gmail.com> wrote: > On Wed, Sep 28, 2011 at 3:27 PM, Junjie Gu <jgu222 at gmail.com> wrote: >> Instrinsic llvm.memory.barrier does not work as expected.  Is it a bug >> or it has not been implemented yet ? > > It's going away in favor of the new fence instruction (and I'll remove > it as soon

If LLVM would like to support OpenMP pragma in the future, not sure if attaching metadata to instructions is still a good choice. Junjie On Wed, Jun 2, 2010 at 11:08 AM, Junjie Gu <jgu222 at gmail.com> wrote: > Thanks for comments/suggestions. > > Yes, attaching metadata to instructions will be good choices for many > cases. But for loops, > attaching metadata to back-edges

Hi, Dear Boissinot: 1. When I have irreducible CFG, I travel its nodes by DFS. search backedge for every node. After I finish one node, push it into a stack. [0, 1, 2, M] <---push. [0, 1, 2, M,...N] <---push. When resolving node M, find a edge from node N to node M, N is not in stack(M < N), It is a backedge. N is in stack(M > N), It is NOT a backedge.

Hi:    I want to do some optimization on MachineLoop. So I want to get MachineLoopInfo from MachineFunction. I reference MachineLICM.cpp. So I try to write a pass in Target/mytarget directory. I find there is Error. llvm/include/llvm/PassAnalysisSupport.h:198: AnalysisType& llvm::Pass::getAnalysisID(const llvm::PassInfo*) const [with AnalysisType = llvm::MachineLoopInfo]: Assertion

Many compilers support per-loop pragma, such as loop unrolling (ie #pragma unroll=2). Is there any LLVM project/effort going on in this area ? What is the expected way for implementing per-loop pragma, or general pragma ? Suggestions/comments ? Thanks Junjie

See http://llvm.org/docs/GettingStarted.html#brokengcc and then try building with something OTHER than GCC 4.1.2 . ----- Original Message ---- > From: Nick Johnson <npjohnso at cs.princeton.edu> > To: LLVM Developers Mailing List <llvmdev at cs.uiuc.edu> > Sent: Monday, May 11, 2009 3:01:12 PM > Subject: [LLVMdev] Pass Manager hangs with CallGraph and LoopSimplify >

Bhavani, A simple way that I'm not sure is 100% guaranteed to work is if the branch is to an earlier or later basic block. Micah -----Original Message----- From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of bhavani krishnan Sent: Wednesday, December 03, 2008 3:20 PM To: Nick Lewycky; LLVM Developers Mailing List Subject: [LLVMdev] Identifying