similar to: Software pipeline using LLVM

Hi, I am extending LLVM for HPC applications. As one of them, I am trying to make MachinePipeliner available on AArch64 + Scalable Vector Extension environment. MachinePipeliner is currently used only by Hexagon CPU. Since it is a very portable implementation, I think that it will actually work just by adding a little code for many CPUs(See Code [2]). The current MachinePipeliner is written on

Sorry to bring this thread from 3 months ago back, but I’m running into this issue too. I do see that shouldIgnore is not called in the MachinePipeliner, however, James’ comment doesn’t really resolve the issue or make the story any clearer. My summary of the comment is: “Hexagon and PPC9 do not need to ignore any instructions. However, in the case that you do, such as when the indvar update is

Hi James, One last thing - is your target upstream? or are you working on a downstream target? Cheers, James On Tue, 8 Sep 2020 at 23:02, Nagurne, James <j-nagurne at ti.com> wrote: > I greatly appreciate you going back to gather that intel, James. It > actually helps my understanding of the whole pipeliner puzzle quite a bit! > > > > I did identify, like you, that the

Hi James, Having not worked on this for circa one year I've gone and refreshed my memory. We have a pretty capable implementation of swing modulo scheduling downstream, distinct from the MachinePipeliner implementation. Historically, MachinePipeliner had very tight coupling between the finding of a suitable schedule and emitting the code that adheres to that schedule. I spent quite a bit of

Hi all, I think there is a mistake in the machinepipeliner interface. In the TargetInstrInfo.h in the class PipelinerLoopInfo there is a function "bool shouldIgnoreForPipelining(const MachineInstr *MI)". The description says that if this function returns true for a given MachineInstr it will not be pipelined. However in reality it is not ignored and is being considered for

Hi, I have some questions about the implementation of Software pipeline in MachinePipeliner.cpp. First, in hexagon backend, between MachinePipeliner and regalloc pass, there're some other passes like phi eliminate, two-address, register coalescing, which may change or insert intructions like 'copy' in MBB, and swp kernel loop may be destroyed by these passes. Why not put

Hi Brendan (and friends of MachinePipeliner, +llvm-dev for openness), Over the past week or so I've been attempting to extend the MachinePipeliner to support different idioms of code generation. To make this a bit more concrete, there are two areas where the currently generated code could be improved depending on architecture: 1) The epilog blocks peel off the final iterations in reverse

Hi James, Adding Hendrik, who has taken over ownership of the downstream code involved. I can also add background about the rationale, of that helps? It was added to ignore induction variable update code (scalar code) that is rewritten when we unroll / peel the prolog epilog anyway. Targets like Hexagon or PPC with dedicated loop control instructions for pipelined loops don't need this, but

Hi James: Personally, I like the idea of refactoring and more abstraction, But unfortunately, I don't know enough about the edges cases either. BTW: the prototype is still causing quite some Asseertions in PowerPC - some nodes are not generated in correct order. Best, Jinsong Ji (纪金松), PhD. XL/LLVM on Power Compiler Development E-mail: jji at us.ibm.com From: James Molloy <james at

Hello, I'm working on integrating the MachinePipeliner.cpp pass into our VLIW backend, and so far we've managed to get it working with some nice speedups. Unlike Hexagon however, our backend doesn't generate hardware loop instructions and so all our loops are a combination of induction variables, comparisons and branches. So when it came to implementing reduceLoopCount for our

Hi James, I also think that refactoring the code generation part is a great idea. That code is very complicated and difficult to maintain. I’ve wanted to rewrite that code for a long time, but just have never got to it. There are quite a few edge cases to handle (at least in the current code). I’ll take a deeper look at your patch. The abstractions that you mention, Stage and Block, are good

Hi - I replied to the original sender only by mistake. Sorry about that. When we started working on the pipeliner, and added it before the scheduler, we also were concerned that the scheduler or other passes would undo the work of the pipeliner. The initial thought was that we would add information (using metadata or some other way like you've suggested) to the basic block to tell the

On 11/6/20 12:39 PM, Sjoerd Meijer wrote: Hello Simon, Thanks for your replies, very useful. And yes, thanks for the example and making the target differences clear: ; Some examples: ; RISC-V V & VE(*): ; %mask = (splat i1 1) ; %evl = min(256, %n - %i) ; MVE/SVE : ; %mask = get.active.lane.mask(%i, %n) ; %evl = call @llvm.vscale() ; AVX: ; %mask = icmp (%i + (seq

I want the optimization to be turned on at -O1 and above. In my case, it is a target independent back-end pass. (Eg: MachinePipeliner) On 2017-01-04 18:10, Mehdi Amini wrote: >> On Jan 4, 2017, at 4:03 PM, Sumanth Gundapaneni via llvm-dev >> <llvm-dev at lists.llvm.org> wrote: >> >> I see the BackendUtil.cpp of Clang creates the TargetMachine with >> the

On 11/6/20 8:49 AM, Roger Ferrer Ibáñez wrote: Hi Sjoerd, Trying to remember how everything fits together here, but could get.active.lane.mask not create the %mask of the VP intrinsics? Or in other words, in the vectoriser, who's producing the %mask and %evl that is consumed by the VP intrinsics? I'm not sure what would be the best way here. I think about the Loop Vectorizer. I imagine

getOptLevel() gets the level from TargetMachine which is created by the Backendutil in clang with either "Default", "None" or "Aggressive". Threre is no correspondence for "Less". This boils down to , if I pass "-O1", the Target Machine is created with CodeGenOpt::Default. I am available on IRC @ sgundapa. -----Original Message----- From:

Here is a problem scenario. I want to enable a backend pass at -O2 or above. if (TM->getOptLevel() >= CodeGenOpt::Default) addPass(&xxxxx); This pass will be run at -O1 too since clang is creating the TargetMachine with CodeGenOpt::Default for -O1. --Sumanth G -----Original Message----- From: mehdi.amini at apple.com [mailto:mehdi.amini at apple.com] Sent: Friday, January 6, 2017

On 05/26/2017 03:02 PM, Matthias Braun wrote: > >> Regarding SDAG, and given that poison is already there, we would need >> to adopt a similar solution to the IR. Maybe right now we can get >> away with it because nsw is not exploited significantly (as you say). >> Just because there’s no explicit poison in SDAG, just having nsw is >> sufficient to cause

On 17 August 2017 at 15:27, Hal Finkel <hfinkel at anl.gov> wrote: > Speaking of benchmarks, we might be able use the library, or some parts of > it, in our test suite for correctness and performance testing. I see some > stand-alone benchmarks that seem useful (e.g., > https://github.com/insideloop/InsideLoop/blob/master/il/benchmark/types/32-vs-64-bit-integers.cpp) > but

Hi all, At the Barcelona Supercomputing Center, we have been working on an end-to-end vectorizer using scalable vectors for RISC-V Vector extension in context of the EPI Project <https://www.european-processor-initiative.eu/accelerator/>. We earlier shared a demo of our prototype implementation  (https://repo.hca.bsc.es/epic/z/9eYRIF, see below) with the folks involved with LLVM