similar to: Inline Spiller spilling multiple duplicate copies

Hi Ryan, > On Mar 14, 2016, at 7:49 AM, Ryan Taylor via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > I looked at this again and it appears that while spillAroundUses sets the register as 'dead', there is no checking to see if it's dead in subsequent iterations of the bundle loop. > > Is this intentional? > > On Mon, Mar 7, 2016 at 3:28 PM, Ryan

Hi Quentin and llvm-dev, I've got a regalloc-related question that you might have an opinion or answer about. In our out-of-tree target we've been doing some bundling before register allocation for quite some time now, and last night a new problem popped up. What the fix should be depends on if this bundle is legal or not: BUNDLE %vreg39<imp-def,dead> *

Hello, for an architecture that doesn't have a good way to load/store a given register class to memory, is it instead easy to spill/fill from another register class instead? e.g. - storeRegToStack/loadRegFromStack use a pseudo instruction and add virtual register operand is not supported (spill optimization doesn't seem to like this). - AMDGPU backend seems to do sth. similar? The only

Ok, thanks. Except the question was meant slightly different. Less w.r.t. organizing the register classes, and more w.r.t. implementation. I've noticed for instance that when trying to model this straight forwardly by writing a vreg from spills and reading this from fills (not further elaborated here), that the spiller can't handle vreg def-use pairs: there are assertions making sure a

Hi all, I'm tracking down a register allocation problem and I'm trying to understand this piece of code in InlineSpiller::spillAroundUses: // Find the slot index where this instruction reads and writes OldLI. // This is usually the def slot, except for tied early clobbers. SlotIndex Idx = LIS.getInstructionIndex(*MI).getRegSlot(); if (VNInfo *VNI =

So I've been designing an experimental 6502 backend for LLVM. Link: <https://github.com/beholdnec/llvm-m6502> The 6502 only has a few registers, one accumulator and two indexes, none of which are large enough to hold an absolute pointer. Because of this, the backend really tests the power of LLVM's register allocator (RA). I've made a change to the RA that might be of interest

I think I'm getting a bit closer to the problem. I've found that the call to InlineSpiller::foldMemoryOperand() inside InlineSpiller::spillAroundUses() is causing the problems. As a test, I removed that call and with your yesterday's patch I'm not getting any errors at all, the code generated is the same one as with the call. This is happening when

Hi Quentin, On 08/19/14 18:58, Quentin Colombet wrote: [...] > It seems that you will have to debug further the *** Bad machine code: Instruction loads from dead spill slot *** before we can be of any help. Yes, I've done some more digging. Sorry for the long mail... I get: Inline spilling aN40_0_7:%vreg1954 [5000r,5056r:0)[5056r,5348r:1) 0 at 5000r 1 at 5056r At this point I have

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 Jun 28, 2017, at 5:10 PM, Quentin Colombet via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Oh wait, vreg1 is indeed used. > Yeah, having a dead flag here sounds wrong. I mean on the instruction itself. On the bundle, that’s debatable. That would fit the semantic “if no side effect you can kill it” (here there is side effect, we define other vregs). > >> On

On Jul 15, 2012, at 9:20 AM, Borja Ferrer <borja.ferav at gmail.com> wrote: > Jakob, one more hint, I've placed some asserts around the code you added and noticed that the InlineSpiller::insertReload() function is not being called. > > 2012/7/14 Borja Ferrer <borja.ferav at gmail.com> > Hello Jakob, > > I'm still getting the error, I can give you any other

On Jul 15, 2012, at 4:50 PM, Borja Ferrer <borja.ferav at gmail.com> wrote: > I think I'm getting a bit closer to the problem. I've found that the call to InlineSpiller::foldMemoryOperand() inside InlineSpiller::spillAroundUses() is causing the problems. > As a test, I removed that call and with your yesterday's patch I'm not getting any errors at all, the code

ola, ive been looking at adding support for an -msave-args option for use on x86_64. the short explanation of it is that it makes x86_64 function prologues store their register arguments on the stack. the purpose of this is to make the arguments trivially accessible for things like stack traces with arguments. as per https://blogs.oracle.com/sherrym/entry/obtaining_function_arguments_on_amd64,

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

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

Jeff Kunkel <jdkunk3 at gmail.com> writes: > Spiller::Spill( LiveInterval *li, >                           SmallVectorImpl<LiveInterval*> &newIntervals, >                           const SmallVectorImpl<LiveInterval*> &spillIs ); > > has two reference vectors which contain a small list of Live > Intervals. What is the register allocator's job to do

Hi Quentin, On 08/15/14 19:01, Quentin Colombet wrote: [...] >> The question is: How should true subregister definitions be >> expressed so that they do not interfere with each other? See the >> detailed problem description below. > > We do have a limitation in our current liveness tracking for > sub-register. Therefore, I am not sure that is possible. > >

Spiller::Spill( LiveInterval *li, SmallVectorImpl<LiveInterval*> &newIntervals, const SmallVectorImpl<LiveInterval*> &spillIs ); has two reference vectors which contain a small list of Live Intervals. What is the register allocator's job to do with these intervals other than analysis. What more needed other than to know

I am observing poor instruction scheduling in my out-of-tree target. The problem is an over-constrained scheduling DAG. In particular, the DAG includes spurious output dependencies on physical, non-register-allocatable registers. MISched already includes code to avoid this problem. However that code relies on information clobbered by the earlier pass LiveVariables. I wonder whether this is a