similar to: [LLVMdev] "Scheduling Hazards" on common architectures

On May 9, 2013, at 4:02 AM, Fraser Cormack <fraser at codeplay.com> wrote: > I have an instruction that takes no operands, and produces two results, in two consecutive cycles. > > I tried both of the following to my Schedule.td file: > > InstrItinData<IIMyInstr, [InstrStage<2, [FuncU]>], [1, 2]>, > InstrItinData<IIMyInstr, [InstrStage<1,

On 09/05/2013 18:25, Andrew Trick wrote: > > On May 9, 2013, at 4:02 AM, Fraser Cormack <fraser at codeplay.com > <mailto:fraser at codeplay.com>> wrote: > >> I have an instruction that takes no operands, and produces two >> results, in two consecutive cycles. >> >> I tried both of the following to my Schedule.td file: >> >>

Hello. Hal, the problem I have is that it doesn't advance at the next available instruction - it always gets the same store. This might be because I did not specify in a file like [Target]Schedule.td the functional units, processor and instruction itineraries. Regarding the Stalls argument to my method [Target]DispatchGroupSBHazardRecognizer::getHazardType() I always get the

I have an instruction that takes no operands, and produces two results, in two consecutive cycles. I tried both of the following to my Schedule.td file: InstrItinData<IIMyInstr, [InstrStage<2, [FuncU]>], [1, 2]>, InstrItinData<IIMyInstr, [InstrStage<1, [FuncU]>, InstrStage<1, [FuncU]>], [1, 2]>, From what I can see in examples, these say that the first

Hello. I am progressing a bit with difficulty with the post RA scheduler (PostRASchedulerList.cpp with ScoreboardHazardRecognizer) - the problem I have is that it doesn't advance at the next available instruction when the overridden ScoreboardHazardRecognizer::getHazardType() method returns NoopHazard and it gets stuck at the same instruction (store in my runs). Just to make sure:

Hello. Hal, thank you for the information. I managed to get inspired from PPCHazardRecognizers.cpp. So I created my very simple [Target]HazardRecognizers.cpp pass that is also derived from ScoreboardHazardRecognizer. My class only implements the method getHazardType(), which checks if, as stated in my first email, for example, I have a store instruction that is storing the value

Hello. I am new to the schedulers implemented in the back end of LLVM. I am trying to handle data hazards in my simple processor, with instructions that execute in 1 cycle. I have tried the standard post-RA scheduler, implemented in lib/CodeGen/PostRASchedulerList.cpp, (with a ScoreboardHazardRecognizer), but I have some issues with some consecutive instructions that are

On Nov 29, 2011, at 10:47 AM, Hal Finkel wrote: > Andy, > > I should have been more clear, the ARM implementation has: > void ARMHazardRecognizer::RecedeCycle() { > llvm_unreachable("reverse ARM hazard checking unsupported"); > } > > How does that work? > > Thanks again, > Hal Hal, My first answer was off the top of my head, so missed the subtle

Hi list, in our LLVM-based-project we are writing a backend for our processor. The architecture is a quite straight-forward RISC, but it does not have hardware interlocks, i.e. data hazards involving memory access must be resolved by the compiler, either by scheduling unrelated instructions or by inserting NOOPs into the load delay slots: ---- For example, code which looks like that: load

On Jan 19, 2009, at 9:17 AM, Patrick Boettcher wrote: > Hi list, > > in our LLVM-based-project we are writing a backend for our > processor. The > architecture is a quite straight-forward RISC, but it does not have > hardware interlocks, i.e. data hazards involving memory access must be > resolved by the compiler, either by scheduling unrelated > instructions or >

On Mon, 2011-12-19 at 22:14 -0800, Andrew Trick wrote: > On Dec 19, 2011, at 3:19 PM, Hal Finkel wrote: > > > On Mon, 2011-12-19 at 07:41 -0800, Andrew Trick wrote: > >> On Dec 19, 2011, at 6:51 AM, Hal Finkel <hfinkel at anl.gov> wrote: > >> > >>> On Tue, 2011-10-25 at 21:00 -0700, Andrew Trick wrote: > >>> Now, to generate the best

On Dec 19, 2011, at 3:19 PM, Hal Finkel wrote: > On Mon, 2011-12-19 at 07:41 -0800, Andrew Trick wrote: >> On Dec 19, 2011, at 6:51 AM, Hal Finkel <hfinkel at anl.gov> wrote: >> >>> On Tue, 2011-10-25 at 21:00 -0700, Andrew Trick wrote: >>> Now, to generate the best PPC schedules, there is one thing you may >>>> want to override. The

Hi, I've been thinking about how to implement a framework for attempting instruction scheduling of small blocks of code by using (GA/simulated annealing/etc) controlled timing-test-evaluations of various orderings. (I'm particularly interested small-ish numerical inner loop code in low-power CPUs like Atom and various ARMs where there CPU doesn't have the ability to

On Dec 20, 2011, at 10:29 AM, Hal Finkel wrote: > On Tue, 2011-12-20 at 10:35 -0600, Hal Finkel wrote: >> On Mon, 2011-12-19 at 23:20 -0800, Andrew Trick wrote: >>> >>> On Dec 19, 2011, at 10:53 PM, Hal Finkel wrote: >>> >>>> Here's my "thought experiment" (from PR11589): I have a bunch of >>>> load-fadd-store chains to

Hi, i'm working on a microblaze port extremely similar to microblaze that only has data hazards. The advice given to look at PPC and ARM is poor because neither of them check for data dependencies and are entirely complicated and different. The port has a 5 stage pipeline where the result of instruction can only be used at stage 3 and 5 only whereas load and store instructions require 4

Andy, I should have been more clear, the ARM implementation has: void ARMHazardRecognizer::RecedeCycle() { llvm_unreachable("reverse ARM hazard checking unsupported"); } How does that work? Thanks again, Hal On Tue, 2011-11-29 at 09:47 -0800, Andrew Trick wrote: > ARM can reuse all the default scoreboard hazard recognizer logic such as recede cycle (naturally since its the

On Mon, 2011-12-19 at 07:41 -0800, Andrew Trick wrote: > On Dec 19, 2011, at 6:51 AM, Hal Finkel <hfinkel at anl.gov> wrote: > > > On Tue, 2011-10-25 at 21:00 -0700, Andrew Trick wrote: > > Now, to generate the best PPC schedules, there is one thing you may > >> want to override. The scheduler's priority function has a > >> HasReadyFilter attribute

On Tue, 2011-12-20 at 10:35 -0600, Hal Finkel wrote: > On Mon, 2011-12-19 at 23:20 -0800, Andrew Trick wrote: > > > > On Dec 19, 2011, at 10:53 PM, Hal Finkel wrote: > > > > > Here's my "thought experiment" (from PR11589): I have a bunch of > > > load-fadd-store chains to schedule. A store takes two cycles to > > > clear > >

Dan: CellSPU could clearly benefit from the post-RA scheduler. In fact, we were thinking about writing a machine pass of our own. One thing that does "disturb" me is that both HazardRecognizer and post-RA sched assume there's only one kind of NOP. For Cell, there are two, depending upon the pipeline being filled. Pipe 0 takes "ENOP" whereas Pipe 1 take

On Sep 24, 2013, at 7:59 PM, Liu Xin <navy.xliu at gmail.com> wrote: > Hi, Andrew, > > Thank you for answering my question. > > What's the status of misched? is it experimental? I found it is disabled by default for all architectures(3.4svn). I also don't understand the algorithm. Could you point to me more papers or text materials about your approach? it seems