similar to: Function attributes for memory side-effects

On 4/29/20 4:12 PM, Reid Kleckner via llvm-dev wrote: > On Tue, Apr 28, 2020 at 12:58 PM Ejjeh, Adel via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> Specifically, I want to be able to know when a called function does not >> have any side effects (e.g. math library functions like sqrt) >> > > Apologies for the pedantry, but I believe sqrt may

Hi all, I am trying to use the dependence analyzer in a pass that I am writing and I was surprised to see an incorrect behavior when I try to query DependenceInfo for dependences between instructions. Specifically, if the two instructions are loads/stores accessing an array in a loop, the depend() method would return a dependence regardless of the order of instructions specified. (i.e. if the two

Hello All I am looking for an LLVM pass that is able to detect branches whose condition is known if they are reached. To illustrate what I mean, I attached a screenshot showing a partial CFG of a function. The branch in basic block for.cond.cleanup3 tests the same condition as the branch in the entry block, and has the same target BB if the condition is false. Also, if you inspect the graph

Hello With the legacy pass manager, we could invoke a Function Pass within the runOnModule() of a Module Pass by simply passing the Function reference to the getAnalysis<>() method. Can the same be achieved using the new Pass Manager? I am writing a Module Pass which requires to access analyses for the different functions, and I need the new pass manager because I need different copies of

Hello I am developing a backend that generates OpenCL from llvm bitcode. I start with a revived fork of the original LLVM C-Backend and have been modifying it. One thing that the backend lacked was generating proper loop structures; instead it relied on labels and goto statements. Therefore, I am trying to find a way to identify the loop structure and print it out in the backend. So far, the main

Hi László, On 8/13/20 5:21 PM, László Radnai via llvm-dev wrote: > (Sorry I clicked reply instead of reply to all) > I'm fighting with my email client, I hope the quoted text contains > what I want it to contain. > > ---------- Forwarded message ---------- > From: László Radnai <radlaci97 at gmail.com> > Date: Fri, 14 Aug 2020 00:11:35 +0200 > Subject:

Hi! I'm interested in what attributes in LLVM mean, specifically how to say that the result is always the same for the given input parameters. The main thing would be to merge two calls with the same parameters when the function is declared but not defined. (just like two stores). I'll call this property mergability. %1 := call @test(%0) %2 := call @test(%0) and the optimization would

Hi Rob, You need to set attribute ReadOnly on the sin / cos functions, using Function::addFnAttr(Attribute) for example. Best regards, -- Arnaud de Grandmaison -----Original Message----- From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Rob Pieke Sent: Monday, November 15, 2010 11:41 AM To: llvmdev at cs.uiuc.edu Subject: [LLVMdev] Optimization of calls

In http://llvm.org/docs/tutorial/LangImpl4.html#jit there's an example that optimizes calls to functions without side effects. Specifically, ready> extern sin(x); ready> extern cos(x); ready> def foo(x) sin(x)*sin(x) + cos(x)*cos(x); Read function definition: define double @foo(double %x) { entry: %calltmp = call double @sin(double %x) %multmp = fmul double %calltmp,

Hi all, My name is Fahad Nayyar. I am an undergraduate student from India. I am interested to participate in GSOC under the project “Improve inter-procedural analyses and optimizations”. I have been using LLVM for the past 8 months. I have written various intra-procedural analysis in LLVM as FunctionPass for my course projects and research projects. But I’ve not contributed to the LLVM

Hi Farad, > I tried to do this for the NoUnwind attribute Hmm, I don't have experience with this attribute but it seems like a good starting point since it doesn't do much. First of all, be sure that you run with: opt -passes=attributor -attributor-disable=false This uses the new pass manager which is another discussion. Now, to the point: If you open nounwind.ll, it has a bunch of

Hi Fahad, > > Improve dynamic memory related capabilities of Attributor. For example > Improve HeapToStackConversions. Maybe such deductions can help safety > (dis)provers. For example, can we improve the use-after-free bug detection > using some attributes? > Stefan should know more about H2S. Regarding the use-after-free, I don't > think there's currently any plans

Currently LLVM removes infinite recursion in readnone functions as dead code. I assume this falls under the same language rules that allow removal of infinite loops. But I need to be certain. Can someone confirm? Standard citations welcome. Otherwise this is wrong: bool mayHaveSideEffects() const { return mayWriteToMemory() || mayThrow() || !mayReturn(); } Note: For non-C support, it

Hi Rob, > I'm using the gvn pass, not sure about basic-aa. if you are using LLVM from svn then you need to specify the basic-aa analysis, otherwise gvn won't unify calls to readonly/readnone functions. This is new behaviour introduced by Dan; probably the tutorial should be updated. Ciao, Duncan. > > I've copied the code as-is from

Hi Suresh, thanks for reporting this! I thought I fixed this with 8d94d3c3b44c3a27a69b153cef9be4b8e481150e. Did you run before or after that commit? Cheers, Johannes On 5/15/20 7:17 AM, Mani, Suresh via llvm-dev wrote: > [AMD Public Use] > > Hi , > > Please ignore the earlier header of Internal and Official use only. > > Thanks > M Suresh > > From: llvm-dev

I'm using the gvn pass, not sure about basic-aa. I've copied the code as-is from http://llvm.org/docs/tutorial/LangImpl4.html#code and added "F->addFnAttr( Attribute::ReadOnly )" after "Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule)". The passes it sets up are: // Set up the optimizer pipeline. Start with registering info about

[AMD Official Use Only - Internal Distribution Only] Hi , There seems to be some issue with attributor, exactly in File Attributor.cpp, Function Attributor::rewriteFunctionSignatures(), Line No: 1600 (approrimate). The llvm source code at above address is as follows: // Eliminate the instructions *after* we visited all of them. for (auto &CallSitePair : CallSitePairs) {

Still no luck after switching to: theFPM->add( new llvm::TargetData( *theExecutionEngine->getTargetData() ) ); theFPM->add( llvm::createBasicAliasAnalysisPass() ); theFPM->add( llvm::createInstructionCombiningPass() ); theFPM->add( llvm::createReassociatePass() ); theFPM->add( llvm::createGVNPass() ); theFPM->add( llvm::createCFGSimplificationPass() ); Based on output

Thank you Hal and Stefan! Bug report is filed: https://bugs.llvm.org/show_bug.cgi?id=46717 And Stefan, I think 'attributor' is a really nice pass, and can infer more precise and useful attributes, which may give more opportunities for optimization. But we shouldn't depend on 'attributor' to correct wrong function attributes, because we cannot run 'attributor' after

On 03/16, Fahad Nayyar wrote: > I can see that Johanned have put up some issues for GSOC aspirants. I think > that [2] <https://github.com/llvm/llvm-project/issues/179> ([Attributor] > Cleanup and upstream `Attribute::MaxObjectSize`) will be a very good issue > for me, It seems doable and I can get familiar with the whole process of > writing a patch for an issue. How should I