search for: optimised

Hi all, I am trying to understand the effectiveness of various llvm optimisations when a language targets llvm (or C) as its backend. The following is my approach (please correct me if I did anything wrong): I am trying to explicitly control the optimisations passes in llvm. I disable optimisation in clang, but instead emit unoptimized llvm IR, and use opt to optimise that. These are what I

Have -O0 on your clang command line causes all functions to get marked with an 'optnone' attribute that prevents opt from being able to optimize them later. You should also add "-Xclang -disable-O0-optnone" to your command line. ~Craig On Thu, Sep 21, 2017 at 10:04 PM, Yi Lin via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi all, > > I am trying to

...6/41) * x + (9/41)) + 24 * log((23/82) + (18/41) * x - 2 * x^2) opt2 <- optimise(ex2, lower=0, upper=(9/41), maximum=T) x <- seq(0,9/41,0.001) plot(x,ex2(x),type="l") abline(v=opt2$maximum, col="red") The two functions are not only of theoretical interest but have to be optimised as likelihood functions when dealing with SNP data. I observed this problem on Windows XP and Open Suse 10.0. Other platforms have to be tested. Some informations: Open Suse 10.0 platform i686-pc-linux-gnu arch i686 os linux-gnu system i686, linux-gnu statu...

I am often asked what optimisations "our" compiler performs at each level. But "our" compiler is actually CLang/LLVM which we have retargeted to our proprietary target. Most of the work we do is in maintaining our target specific backend. Certainly there are optimisations that we do to take best advantage of our instruction set during lowering and instruction selection, and

I noticed that there is a '-run-pass' argument for llc. I am wondering if I can do a similar approach with machine level optimisations/passes for llc. Are those passes optional (so I can turn them off)? And how can I get MIR format as llc expects with '-run-pass'? Thanks a lot. Cheers, Yi On 22/9/17 15:10, Craig Topper wrote: > Have -O0 on your clang command line causes

Right but then you'll have to call each opt level. Have u looked in the pass manager? On Jun 24, 2017 3:52 PM, "Sean Silva via llvm-dev" <llvm-dev at lists.llvm.org> wrote: > The most definitive list you can probably hope to get will be obtained by > passing -mllvm -debug-pass=Structure to a clang invocation. > > -- Sean Silva > > On Jun 24, 2017 7:10 AM,

On Mon, Jun 26, 2017 at 5:04 AM, ORiordan, Martin <martin.oriordan at intel.com > wrote: > Thanks Sean and Silva. > > > > I guess what I was seeking was a URL that I could point (non-compiler) > people at, but I guess no such reference exists. What I can do if > reference bot the source manager and use ‘-mllvm -debug-pass=Structure’ > for each optimisation level,

Hi there, I have a piece of Matlab code I use to optimise a trding strategy. If there are any Matlab/R specialists out there, I would appreciate your help in doing the exact same optimisation in R. I suspect I would use nlm() in R but am not sure where to define my constraints. I have attached my Matlab code below for reference. Many thanks. Constraints function [c,ceq]=TriskellConstraints(X)

I agree, it's much clearer, it just takes runs at multiple opt levels and therefore I don't find it to be a "one stop shop". On Jun 24, 2017 8:44 PM, "Sean Silva" <chisophugis at gmail.com> wrote: > Looking at PassManagerBuilder can be useful because there are sometimes > comments giving some idea of the intent of the particular choice of passes, > but

With LLVM v5.0, I found failures in some of the 'gcc.c-torture/execute' tests due to a change in the optimisation where undefined behaviour is involved. The tests that fail are the '20040409-[123].c' tests. The underlying failure is due to the optimisation of the following: int test2(int x) { return x + INT_MIN; } from using an ADD instruction to using an OR instruction.

Hi Sanjoy, Yes these are C tests (from 'gcc.c-torture/execute'), and as I indicated in my original message, the tests are not valid because the behaviour is undefined. However, it was while investigating these new failures in these tests that I realised that this optimisation existed. The optimisation itself is perfectly valid, but it does mean that integer underflow will no longer be

Hello, We have developed a compiler analysis for multi-threaded codes that identifies functions which do not modify global variables. Furthermore, the analysis checks that accesses performed before the function call, do not target the same location as accesses performed after the call (hence, the variables accessed before and after the call do not alias). We want to integrate this analysis

...pport. What can i do, to reduce RAM consumption? I mean very serious RAM optimisations. Deleting not used structure fields, etc... May be I can do something with alloc... Help me to determine that it is possible to throw out. What is best result(in RAM optimisation)? Also i am going to use TI optimised FFT.

> As far as I know, ObjectFile is either COFF, ELF or MachO format, > statically compiled. But the pass manager for applying optimisation > passes works only on llvm-ir. I would not need to apply optimisations on the parts of the program in the object file. These are meant to be optimised beforehand. The only parts I want to run passes on are specific function that I know beforehand. > What you can do is to isolate the function you want to jit by > extracting it to a new module. Load this module during runtime, > apply your pass and jitting it. Yes this is exactly...

...to the new function. This leaves us with two functions that have the same semantic effect: - One has its address taken, and may have external visibility. Just calls the other. - One does not have its address taken and has internal visibility Direct call sites to the outer wrapper/trampoline can be optimised to direct calls to the new internal function, leaving no net change other than enabling other optimisations. Uses of the address of the symbol are unchanged as the original function is still present. Indirect call sites now go through this trampoline to share the code. There's the runtime cost...

...either and the optimisation doesn't happen at all. Is there a way of tracing what "clang" actually does and extracting the intermediate representation between the phases? Or is this a question for cfe-dev? (I'm currently trying to understand how some conditional expressions are optimised.) Thanks for any advice. -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or...

Hello, I would like to build samba at different optimisation levels with debug symbols, in order to test a static analysis tool I have developed. I have found the configure option "--enable-developer", which I presume enables debug symbols and sets optimisation to O0, however I would also like to be able to enable debug symbols and set the optimisation level to O2. I cannot find a way

...10 at 8:18 AM, Pekka Nikander <pekka.nikander at nomadiclab.com> wrote: > I am working on heavily optimising unusually static C++ code, and have encountered a situation where I basically want an optimiser that would speculatively unroll a loop to see if the first round of the loop could be optimised further.  (I happen to know that it is possible.)  The previous optimisations that produce the loop in the first place already do a magical job (relying heavily on constant propagation), transforming cross-class tail recursion into the loop that I am now addressing. Hence, there is probably little...

I'm fairly new to LLVM, and am writing an optimisation pass to be run by 'opt'. However, i'd like this pass to be parameterisable; as such i'd like to be able to pass an option to it (preferably via the command line to 'opt'). e.g. so i can do something like this "opt -load mypass.so -MyPass=MyPassOption < inputfile.bc ..." (for example one thing I would

...ions 27 CentOS 6 guest on CentOS 5 host with no optimisations 32 CentOS 6 guest on CentOS 5 host with no optimisations Here are the figures a CentOS 6 guest running on the CentOS 6 host with various optimisations. Even with these optimisations, performance doesn't come close to the un-optimised guest running on the CentoOS 5 host: 5 No optimisations (i.e. same configuration as on CentOS 5) 4 deadline scheduler 5 deadline scheduler 15 noatime,nodiratime 14 noatime,nodiratime 15 noatime 15 noatime + deadline scheduler 13 virtio 13 virtio 10 virtio + noatime 9 virt...