similar to: Problem of getting two unused registers in eliminateFrameIndex()

Hi! I started writing a LLVM backend for a custom architecture. I have some register and instruction .td files and some other files/classes like a MCStreamer for assembler output. At the moment I can compile some empty programs so far. I implemented the method ::eliminateFrameIndex() similar to the Sparc and ARM backend. The method looks like this: // frame pointer is in reg of class

I need to use ‘createVirtualRegister’ for a specific case in my ‘eliminateFrameIndex’ function implementation. However, whenever that code is executed, I get the assertion "MachineCopyPropagation should be run after register allocation!” at a later stage. I have seen that at least a couple of backend implementations (including ARM Thumb) create virtual registers in ‘eliminatedFrameIndex’.

Thanks Jon and Hal for the helpful pointers. By returning true from requiresRegisterScavenging() and requiresFrameIndexScavenging(), LLVM handled all the scavenging effort. That is nearly painless for the target, so why do some targets seem to do scavenging on their own? When the scavenged register is loaded with a simple immediate, is it safe to search the BB and replace other uses of the same

On 1/29/15 2:00 PM, Steve King wrote: > Hello LLVM, > The ARM target sometimes adds an instruction with a virtual register > in eliminateFrameIndex(): > > https://github.com/llvm-mirror/llvm/blob/master/lib/Target/ARM/ARMBaseRegisterInfo.cpp > > This looks late for a virtual register to appear. Where is this vreg made real? The register scavenger should take care of such

Hello LLVM, The ARM target sometimes adds an instruction with a virtual register in eliminateFrameIndex(): https://github.com/llvm-mirror/llvm/blob/master/lib/Target/ARM/ARMBaseRegisterInfo.cpp This looks late for a virtual register to appear. Where is this vreg made real? Thanks, -steve

----- Original Message ----- > From: "Steve King" <steve at metrokings.com> > To: jonathan at codesourcery.com > Cc: llvmdev at cs.uiuc.edu > Sent: Friday, January 30, 2015 10:52:19 AM > Subject: Re: [LLVMdev] creating a vreg in eliminateFrameIndex() > > Thanks Jon and Hal for the helpful pointers. By returning true from > requiresRegisterScavenging() and

On Fri, Jan 30, 2015 at 8:59 AM, Hal Finkel <hfinkel at anl.gov> wrote: >> When the scavenged register is loaded with a simple immediate, is it >> safe to search the BB and replace other uses of the same immediate >> with the reg? In my case this gives a code size reduction. The >> search would stop on finding another use of the scavenged register. > > Are you

The docs for the above-mentioned function say: This method may modify or replace the specified instruction, as long as it keeps the iterator pointing the the finished product. What does it mean to "keep an interator". Was "invalidates the iterator" intended, so something else. Another question, is how do I really replace the instruction. The operator= is private

On Oct 10, 2011, at 10:26 AM, Richard Osborne wrote: > I'm investigating a bug associated with debug information that manifests > itself in the XCore backend (PR11105). I'd like to understand what the > expected behavior of eliminateFrameIndex() is when it is called on a > dbg_value machine instruction. That is up to the target. The TII::emitFrameIndexDebugValue() hook is

I'm investigating a bug associated with debug information that manifests itself in the XCore backend (PR11105). I'd like to understand what the expected behavior of eliminateFrameIndex() is when it is called on a dbg_value machine instruction. Currently the XCore target replaces the frame index with the frame register and sets the next operand to the byte offset from the frame

> On Sep 26, 2017, at 2:39 PM, Geoff Berry via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hi all, > > Mikael reported a machine verification failure in his out-of-tree target with the MachineCopyPropagation changes to forward registers (which is currently reverted). The verification in question is: > > *** Bad machine code: Multiple connected components in live

On 9/26/2017 6:11 PM, Matthias Braun wrote: > >> On Sep 26, 2017, at 2:39 PM, Geoff Berry via llvm-dev <llvm-dev at lists.llvm.org> wrote: >> >> Hi all, >> >> Mikael reported a machine verification failure in his out-of-tree target with the MachineCopyPropagation changes to forward registers (which is currently reverted). The verification in question is:

> On Sep 26, 2017, at 3:33 PM, Geoff Berry <gberry at codeaurora.org> wrote: > > > > On 9/26/2017 6:11 PM, Matthias Braun wrote: >>> On Sep 26, 2017, at 2:39 PM, Geoff Berry via llvm-dev <llvm-dev at lists.llvm.org> wrote: >>> >>> Hi all, >>> >>> Mikael reported a machine verification failure in his out-of-tree target

Hi all, Mikael reported a machine verification failure in his out-of-tree target with the MachineCopyPropagation changes to forward registers (which is currently reverted). The verification in question is: *** Bad machine code: Multiple connected components in live interval *** - function: utils_la_suite_matmul_ref - interval: %vreg77

Hi, I have the following code: %a1<def> = COPY %a0<kill> ... %a0h<def> = COPY %a1l , as input to MachineCopyPropagation. The second copy is illegally erased! This is wrong, because it is the low part of a1 that is copied to the high part of a0. At a first glance, it seems that if (!ReservedRegs.test(Def) && (!ReservedRegs.test(Src) ||

On 10/10/11 19:19, Jakob Stoklund Olesen wrote: > On Oct 10, 2011, at 10:26 AM, Richard Osborne wrote: >> I'm investigating a bug associated with debug information that manifests >> itself in the XCore backend (PR11105). I'd like to understand what the >> expected behavior of eliminateFrameIndex() is when it is called on a >> dbg_value machine instruction. >

On 9/26/2017 6:47 PM, Matthias Braun wrote: > >> On Sep 26, 2017, at 3:33 PM, Geoff Berry <gberry at codeaurora.org >> <mailto:gberry at codeaurora.org>> wrote: >> >> >> >> On 9/26/2017 6:11 PM, Matthias Braun wrote: >>>> On Sep 26, 2017, at 2:39 PM, Geoff Berry via llvm-dev >>>> <llvm-dev at lists.llvm.org

> On Sep 26, 2017, at 8:24 PM, Geoff Berry via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > On 9/26/2017 6:47 PM, Matthias Braun wrote: >>> On Sep 26, 2017, at 3:33 PM, Geoff Berry <gberry at codeaurora.org <mailto:gberry at codeaurora.org> <mailto:gberry at codeaurora.org <mailto:gberry at codeaurora.org>>> wrote: >>> >>>

Hi, anyone know anything about copy propagation? Matthias, I see this was your code originally? Was there some assumptions you made? I'm hitting an assertion in MachineCopyPropagation::isNopCopy: if (Src == PreviousSrc) { assert(Def == PreviousDef); return true; } This code compares two COPY instruction to see whether they are effectively "the same". The assert assumes

Forgive me if these questions are naive or if I'm misunderstanding something. I'm certainly very interested in seeing the MachineCopyPropagation patch finally land and stick. 1. Wouldn't function live-ins and reserved registers have started life as physical registers already? For example, wouldn't a live-in be a copy from a physical register to a virtual one allowing the flag to