similar to: GlobalISel round table follow up: register bank select

Hi Quentin, thanks for picking up the conversation! > I think we should step back and check what we want before investing any time in some rewrite. That is a very fair point and I might have been getting ahead of myself in my last email. What I would like to see from RegBankSelect is to produce the mapping with the overall lowest cost. Keeping track of all different combinations of

Hi Quentin, Am 08.10.20 um 21:17 schrieb Quentin Colombet: > Hi Dominik, > >> On Oct 8, 2020, at 5:03 AM, Dominik Montada >> <dominik.montada at hightec-rt.com >> <mailto:dominik.montada at hightec-rt.com>> wrote: >> >> Hi Quentin, >> >> thanks for picking up the conversation! >> >> > I think we should step back and

Hi Quentin, thank you for the reply! I have a couple more questions that came up when I tried to implement this today. I hope you can help me out with this again! Am 09.03.20 um 23:31 schrieb Quentin Colombet: > I would expect that you could create a register class and register > bank for the special register. That way you have something to map to > when you do register bank select.

Hi Quentin, thank you for the reply! This clears up a lot of the questions I was having. It seems like we should definitely invest some time in rewriting some of our legalization rules then! I also posted some questions further down below. I would appreciate getting your opinion on them. > Hi Dominik, > > I’ll do a brief reply here and if you want more information we can talk further

Hi, GlobalISel currently drops all type information relating to the integer/FP distinction during the IR translation pass, as the LLT types only represent whether a value is a scalar/vector/pointer and it’s size/shape. To compensate, later passes use the FP operations on those values to guess what kind of value is being stored within that virtual register. This means that i32/float loads get

Hi Quentin, Hi Amara, I was following your discussion on D75086 regarding declaring types as legal even if they are smaller than the actual register class (e.g. s16 and gpr32). We are working on a backend which only has 32 and 64-bit registers and we recently had a problem regarding exactly this where we had to declare G_UNMERGE_VALUES and G_MERGE_VALUES with a smaller type of <s32 as

I don’t think bfloat should be handled this way. What Amara is suggesting is an optimization, i.e., if we drop the information we are still correct. With bfloat, if we do an operation on float16 instead of bfloat16 this is a correctness problem. So that means that either we need to have new opcodes for bfloat or we need to carry around the floating point type in MIR. I think it would be more

Hi, I've spent some time playing around with GlobalISel on the AMDGPU target, and I was wondering if there is any reason to have RegisterBankInfo::getInstrAlternativeMappings() and RegisterBankInfo::getInstrMapping() as separate functions. Could we instead replace these two functions with just one: RegisterBankInfo::getInstrMappings() and then just treat the first mapping in the list as the

Hi all, first of all thanks to Matt for hosting the round table yesterday and to everyone else for their time and the valuable discussions. As promised in the chat yesterday, here is the email regarding the legalizer / artifact combiner issue we talked about. I will send a separate email regarding the regbankselect discussion. In case someone on the list didn't attend the round table

> On May 5, 2020, at 2:45 PM, Ties Stuij <Ties.Stuij at arm.com> wrote: > > Quentin: Thanks for the info. I was under the impression that the LLVM community at large would prefer to extend the IR type to a bfloat MVT type. I've made a number of patches to implement this up to a point for AArch64. I can post those on Phab and start a thread to sample opinions. Sounds good to

> On May 1, 2020, at 10:28 AM, Arsenault, Matthew <Matthew.Arsenault at amd.com> wrote: > > [AMD Public Use] > > > It seems to me like you're looking for a workaround for the fact that nobody has put any serious optimization effort into RegBankSelect Practically speaking, we have a compile time budget, and spending that on reconstructing information which we

Hi Medhi, > On Dec 11, 2015, at 6:18 PM, Mehdi Amini <mehdi.amini at apple.com> wrote: > > Hi, > > Side note: shouldn’t RFCs rather go to llvm-dev? You’re right! I could have sworn I have sent it to llvm-dev! Moving it now. > >> On Dec 11, 2015, at 5:44 PM, Quentin Colombet via llvm-commits <llvm-commits at lists.llvm.org> wrote: >> >> Hi,

Hi Dominik, Thanks for your reply. In my case, the Defs is the cause of the problem. Or rather, it is part of the problem, because when I remove it from the instruction TableGen gives me a different error message which concerns a part which is deeper into the pattern tree, so at least it is able to proceed beyond that part of the pattern. I have also stepped TableGen inside gdb and

Hi Daniel, Thanks for replying; I was hoping to get in touch with you on this issue. I had a look at how SelectionIDAG does it when generating the matcher table, and it does consider the implicit defs as additional output. Here is the match table generated for the pattern: /* 0*/ OPC_CheckOpcode, TARGET_VAL(ISD::SIGN_EXTEND), /* 3*/ OPC_MoveChild0, /* 4*/ OPC_CheckOpcode,

Hi, We're working on adding exception handling support for a downstream bare-metal target. I read through the LLVM exception handling docs [1] and went through some patches from other backends to understand what parts we need to implement. We're now at a point were it feels like it should work, but unfortunately exceptions are still not getting caught. Our target uses DWARF

Hi all, After a recent upstream merge into our downstream sources we are suddenly encountering the freeze instruction in LLVM IR for div/rem pairs. This seems to be related to [1]. Our downstream target is GlobalISel only and unfortunately GlobalISel doesn't support this instruction yet, so most of our internal test-suite is now breaking due to GlobalISel not being able to translate this

I just landed these patches: commit c55051eea5d3cd57abfd9727f519b670517704d9 Author: Louis Dionne <ldionne at apple.com> Date: Thu Jun 25 12:02:43 2020 -0400 [libunwind] Allow specifying custom Lit config files This is the libunwind counterpart of 0c66af970c80. commit 33c9c10d183371edc95fa936705bef56f55ab611 Author: Louis Dionne <ldionne at

Hi Matt, thanks for responding. I left a couple of comments down below. Am 24.03.20 um 18:26 schrieb Matt Arsenault: > >> On Mar 24, 2020, at 12:24, Dominik Montada via llvm-dev <llvm-dev at lists.llvm.org> wrote: >> >> Hi all, >> >> recently when working with GlobalISel we have often encountered cases in the legalizer where instructions could not be

Hi all, recently when working with GlobalISel we have often encountered cases in the legalizer where instructions could not be narrowed because the narrowing code relies on G_UNMERGE_VALUES and therefore requires the source type to be a multiple of the narrow type. Often times these instructions can be widened without any problem to a fitting type. This has us writing legalization rules like

Hi Louis, sorry for bothering you once more about the libcxx test suite! I was wondering whether you could help with some of my problems again. After the recent discussion on the mailing list and your diff, I was able to set up cross-compilation and remote-execution of the libcxx test suite, so thank you for that! We have split up the build of the libraries into different stages, so libcxx,