similar to: Deopt operand bundle behavior

> On Oct 31, 2014, at 5:28 PM, Sanjoy Das <sanjoy at playingwithpointers.com> wrote: > > Hi Kevin, > > Thank you for starting this discussion! Yes, sorry for being unresponsive for a few days. Sanjoy summarized the issues perfectly. > I think the distinction is really between whether the live values are > "live on call" or "live on return".

This is a follow up on a conversation some of us had at the hacker lab -- I noticed that sometimes I will get notified that a deopt value lives in a register that is not callee-save (caller-save I guess, but is there another term for this that is less similar to callee-save?). This surprised me quite a bit since those registers immediately got clobbered by the call inside the patchpoint, so we

On Wed, Feb 17, 2016 at 8:53 PM, Philip Reames <listmail at philipreames.com> wrote: > I think you're jumping ahead a bit here. I'm not sure the semantics are > anywhere near as weird as you're framing them to be. :) I now think this weirdness actually does not have to do anything with guard_on or bail_to_interpeter, but it has to do with deopt bundles itself. Our

This is a proposal to add guard intrinsics to LLVM. Couple of glossary items: when I say "interpreter" I mean "the most conservative tier in the compilation stack" which can be an actual interpreter, a "splat compiler" or even a regular JIT that doesn't make optimistic assumptions. By "bailing out to the interpreter" I mean "side exit" as

[+CC llvm-dev this time] Hi, As discussed in the review thread in http://reviews.llvm.org/D16439, the future plan around statepoints, deopt bundles, PlaceSafepoints etc. is to "constant fold" -spp-no-statepoints and -rs4gc-use-deopt-bundles to true. We (Azul) have moved to a representation of safepoint polls, deopt state etc. that enables us to do the above; and at this point I'm

On Wed, 9 Sep 2020 at 19:26, Nemanja Ivanovic <nemanja.i.ibm at gmail.com> wrote: > - Default (i.e. no -profile-deopt-cold): do nothing > - Option with no arg (i.e. -profile-deopt-cold): add attribute only to > functions that have an execution count of zero > - Option with an arg (i.e. -profile-deopt-cold=<N>): add attribute to > functions that account for <N>% of

Sanjoy gave the long answer, let me give the short one. :) "deopt" argument bundles are used in the middle end, they are lowered into a statepoint, and generate the existing stackmap format. i.e. one builds on the other. On 02/18/2016 11:43 AM, Eric Christopher wrote: > Hi Sanjoy, > > A quick question here. With the bailing to the interpreter support > that you're

As part of adding `"deopt"` operand bundles, we're aiming to change RewriteStatepointsForGC (called RS4GC henceforth) from rewriting existing `gc.statepoint` calls to transforming normal LLVM calls and invokes into `gc.statepoint` calls and invokes (i.e. to do PlaceSafepoints + RS4GC in one step). This will make `gc.statepoint` an artifact of the gc lowering strategy that only

Assuming everyone is on the same page, here's a rough high level agenda: # step A: Introduce an `interposable` function attribute We can bike shed on the name and the exact specification, but the general idea is that you cannot do IPA / IPO over callsites calling `interposable` functions without inlining them. This attribute will (usually) have to be used on function bodies that can

Hello Everyone, I want to raise a discussion about @llvm.experimental.guard intrinsic and reasons why we should give up using it. Here is an alternative approach to representation of guards that resolves some of fundamental flaws that the current guards have. Basically, this intrinsic was introduced to model the following situation: we want to check that some condition is true, and if it's

Hi, Sanjoy, On 2015-11-16 23:27, Sanjoy Das wrote: > Hi Vlad, > > vlad via llvm-dev wrote: >>> Vlad, >>> >>> My initial impression is that you've stumbled across a bug. I suspect >>> that we - the only active users of the deopt info in the statepoint I >>> know of - have been inverting the meaning of Direct and Indirect >>>

On Wed, 9 Sep 2020 at 14:27, Nemanja Ivanovic <nemanja.i.ibm at gmail.com> wrote: > A more aesthetic comment I have is that personally, I would prefer a > single option with a default percentage (say 0%) rather than having to > specify two options. > 0% doesn't mean "don't do it", just means "only do that to functions I didn't see running at

Hello, list I am not quite sure if what I'm experiencing is a bug or intentional behavior. In the code below the result of a function call is a deopt arg to llvm.experimental.gc.statepoint (http://llvm.org/docs/Statepoints.html#llvm-experimental-gc-statepoint-intrinsic). Therefore a Stack Map containing location of this variable is created upon code generation. Here's the complete

Just wanted to confirm that I too like where this is going. =] I think Philip and others have really handled the bulk of the review, and I'm very comfortable with them finishing the patch review. One issue where I wanted to chime in, hopefully just to add some clarity, is the "readonly" vs operand bundle set of (interrelated) issues. First, as I think Philip already said, I think

We would like to propose a new feature to disable optimizations on IR Functions that are considered “cold” by PGO profiles. The primary goal for this work is to improve code optimization speed (which also improves compilation and LTO speed) without making too much impact on target code performance. The mechanism is pretty simple: In the second phase (i.e. optimization phase) of PGO, we would add

Hi Sanjoy, Thanks for feedback! As for memory effects, currently I use " inaccessiblememonly " for it. It allows to prove that it doesn't alias with any other load/store in the function, but doesn't allow CSE to eliminate it. It is not actually super-cool, because there is no way that we can safely hoist it out of loop (and sometimes we want to, for example to make unswitching).

Replies inline. At a high level, it feels like we'll eventually need a new instruction to represent the kind of control flow a guard entails (to be clear: we should probably still start with an intrinsic) -- they are fairly well-behaved, i.e. readonly, nounwind etc. as far as the immediate "physical" caller is concerned, but not so as far as its callers's callers are concerned.

Hi Andy, Thanks for replying, responses inline below: On Fri, Feb 19, 2016 at 11:12 AM, Andrew Trick <atrick at apple.com> wrote: > This clearly doesn't need operand bundles, but using an intrinsic > would permit special code motion semantics. It could be hoisted and > merged with other traps, but the condition could never be widened > beyond the union of the original

We'd like to propose a scheme to attach "operand bundles" to call and invoke instructions. This is based on the offline discussion mentioned in http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-July/088748.html. # Motivation & Definition Our motivation behind this is to track the state required for deoptimization (described briefly later) through the LLVM pipeline as a

> Vlad, > > My initial impression is that you've stumbled across a bug. I suspect > that we - the only active users of the deopt info in the statepoint I > know of - have been inverting the meaning of Direct and Indirect > throughout our code. (i.e. we're consistent, but swapped on the > documented meaning) I've asked Sanjoy to confirm that, and if he >