similar to: [LLVMdev] LLVM Scheduler and Itinieraries: Negative latency?

Forwarding to llvm-dev... ---------- Forwarded message ---------- From: Magnus Pettersson <mangepe at gmail.com> Date: Thu, Apr 14, 2011 at 21:33 Subject: Re: [LLVMdev] LLVM Scheduler and Itinieraries: Negative latency? To: Anton Korobeynikov <anton at korobeynikov.info> Hello Anton, I am trying to model a fairly simple five stage pipelined processor. The problem is that some

Hello Magnus, > I am trying to model a fairly simple five stage pipelined processor. Ok. > The problem is that some instructions need the last stage (write back) to be > finished so the correct operand is selected for a following instruction in > stage 3. Ok, this is pretty typical. > machine cycles and higher values for when the result is ready (3) and when > the operands are

----- Original Message ----- > From: "Rail Shafigulin via llvm-dev" <llvm-dev at lists.llvm.org> > To: "llvm-dev" <llvm-dev at lists.llvm.org> > Sent: Monday, November 9, 2015 10:09:07 AM > Subject: Re: [llvm-dev] Is there a way to convert between SchedMachineModel and Itineraries? > > > Anybody? Does anyone at all know how to do it? There is

Is there a way to convert between SchedMachineModel and Itineraries? I was trying to write a very simple VLIW packetizer (Hexagon was my starting point). It turns out that current DFAPacketizer is using itineraries, but my schedule is based on SchedMachineModel (I was recommended to use it since the itineraries are being phased out). I was wondering if there is an automated tool that would

> On Nov 9, 2015, at 10:49 AM, Rail Shafigulin <rail at esenciatech.com> wrote: > > On Mon, Nov 9, 2015 at 10:31 AM, Hal Finkel <hfinkel at anl.gov <mailto:hfinkel at anl.gov>> wrote: > ----- Original Message ----- > > From: "Rail Shafigulin via llvm-dev" <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> > > To:

Hi, What is the best way to model a scheduler for a VLIW in-order architecture? I've looked at the Hexagon and R600 architectures and they are using itineraries. I wanted to understand the benefit in using itineraries over the per operand scheduling. I also found this thread from almost 2 years ago: http://lists.llvm.org/pipermail/llvm-dev/2016-April/098763.html At that time it seemed the

> On Feb 4, 2018, at 9:15 AM, Yatsina, Marina via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hi, > > What is the best way to model a scheduler for a VLIW in-order architecture? > I’ve looked at the Hexagon and R600 architectures and they are using itineraries. I wanted to understand the benefit in using itineraries over the per operand scheduling. > > I

Hi Krzysztof, 2018-02-08 13:32 GMT+08:00 Andrew Trick via llvm-dev < llvm-dev at lists.llvm.org>: > > > On Feb 4, 2018, at 9:15 AM, Yatsina, Marina via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > > Hi, > > What is the best way to model a scheduler for a VLIW in-order architecture? > I’ve looked at the Hexagon and R600 architectures and they are using

We have a two different dimensions for each instruction: slot assignments, and operand timings. These two are unrelated to each other, and also each (or both) can change for any given instruction from one architecture version to the next. The main concern for us was which of these mechanisms contains all the information that we need. We cannot express all the scheduling details by hand, and

It it possible to specify an instruction latency in the itinerary through a command line option? We have several options for a hardware divider which have different latencies and it would be nice if I could specify it through a compiler option rather than changing the value in the code and recompiling llvm every time? Any help is appreciated. -- Rail Shafigulin Software Engineer Esencia

Hi Phil. You more or less answered your own question, but let me give you some more info. Maybe it is of use. >From what I understand the SchedMachineModel is the future, although it is not as powerful as itineraries at present. The mi-scheduler is mostly developed around out-of-orders cores, I believe (I love to hear arguments on the contrary). Some of the constraints that can be found in

Hi everyone I'm fairly new with LLVM and I've been searching around but couldn't find info on this subject. I started working on a target for a new cpu and I realizing my initial simple understanding of instruction itineraries may be completely off. I'm trying to model a CPU that has a latency of 2 cycles for multiplications fully pipelined (so it can start a new one after one

So if I use the SchedMachineModel method, can I just skip itineraries? Phil On Wed, Apr 20, 2016 at 12:29 PM, Sergei Larin <slarin at codeaurora.org> wrote: > Target does make a difference. VLIW needs more hand-holding. For what you > are describing it should be fairly simple. > > > > Best strategy – see what other targets do. ARM might be a good start for > generic

Hello Andy, Thank you for your offer to work together on implementing the your new scheduler on X86. I can start working on this right away. In case you were unaware, the new Silvermont micro-architecture is only out of order on the integer side. The SSE instructions are still in order, so the current postRA scheduler is very beneficial for code with lots of SSE instructions, such as the ISPC

Hi, I am having some trouble understanding the scheduling scheme for the C-A9. Looking at the ARMScheduleA9.td file I find this line that overrides the target SchedWrite with processor specific latencies. def : SchedAlias<WriteALU, A9WriteALU>; However, in this same file, I find the lines presented below, which are mapping the SchedReadWrite to, for example, the ANDri instruction. //

Hi, I just switched to the 2.5 release branch and noticed that llc runs into the following assert in ScheduleDAGList::ScheduleNodeTopDown() using our custom backend: assert(!I->isAssignedRegDep() && "The list-td scheduler doesn't yet support physreg dependencies!"); It turns out that the register dependency concerns the condition code register which is

The best fix is to teach this scheduler how to deal with these dependencies. :-) If you just want a check, I think it's easier to just check register class's copy cost. -1 means it's extremely expensive to copy registers in the particular register class. Evan On Feb 6, 2009, at 2:22 AM, Christian Sayer wrote: > Hi, > > I just switched to the 2.5 release branch and

On Mon, Aug 15, 2011 at 4:03 PM, Miguel G <miguel at esenciatech.com> wrote: > Hi everyone > I'm fairly new with LLVM and I've been searching around but couldn't find > info on this subject. > I started working on a target for a new cpu and I realizing my initial > simple understanding of instruction itineraries may be completely off. > I'm trying to model a

hi, LLVM, I found there is a flag DisableHazardRecognizer in TargetInstrImpl.cpp. I still don't understand how llvm detects data hazard in pre-RA-sched. pre-RA-sched is based on SDNode and all operands are vregs. Even you can calculate the operators of SDNodes, the data hazard in vreg are not same as physical register data hazard. Is it useful to optimize processor pipeline? thanks, --lx

Does anybody know how to specify instruction latency in the itinerary scheduling model? For some reason no matter what I do I get a latency of 1. -- Rail -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20151111/161bd6cb/attachment.html>