similar to: [LLVMdev] Making optimization passes do less

Hello David, I am having an issue with some custom intrinsics that return a token value: InstCombine deletes the users of the token but not the instruction that creates the token itself. The IR is still valid but it's wasted. The source of the issue is coming from an old patch of yours: commit 7204cff0a121ebc770cf81f7f94679ae7324daae Author: David Majnemer <david.majnemer at

Hi Mark, It is not clear to me at all that preventing the merging is the right solution. There are a large number of analysis, including alias analysis, and optimizations that use GetUnderlyingObject, and related routines to search back through GEPs. They only do this up to some small finite depth (six, IIRC). So reducing the GEP depth is likely the right solution for InstCombine (which has the

Yes, it's still respected in this case, as the only instructions that will be deleted have been RAUW with undef. Originally, all instructions where RAUW but only non-EHPad were deleted (that means EHPad were RAUW but not deleted). Then it was later patched by not RAUW token instructions and now not deleting EHPad nor token instructions. My assumption is that the instructions we wanted to

> There should be no difference between using llvm-gcc at some -O > level, and running it at -O0 and using opt to run the passes on > the unoptimized bitcode. However, you wrote earlier: > Finally, llvm-gcc runs the following passes on each function > immediately after it is created: > > CFGSimplification, PromoteMemoryToRegister, > ScalarReplAggregates,

On 3/21/06, Chris Lattner <sabre at nondot.org> wrote: > On Mon, 20 Mar 2006, Michael McCracken wrote: > > > Hi, I'm trying to access an analysis pass from the Inliner pass, and > > I'm having a lot of trouble getting that to work - I can verify that > > my pass is loaded and run (it is a dynamically loaded pass that is > > part of an analysisgroup),

On Nov 30, 2007, at 20:59, Jon Harrop wrote: > Does LLVM hoist bounds checks out of inner loops? In practice, LLVM is frequently going to have conservative behaviors which will prevent hoisting the explicit bounds checks your front-end must generate. Specifically, LLVM must use alias analysis to disprove the hypothesis that the array length variable is updated by the body of the loop.

I did not observe any assertion. In addition, the documentation ( https://llvm.org/docs/LangRef.html#undefined-values) says: The string ‘undef’ can be used anywhere a constant is expected, and indicates that the user of the value may receive an unspecified bit-pattern. Undefined values may be of any type (other than ‘label’ or ‘ void’) and be used anywhere a constant is permitted. Either way,

On Mon, Feb 23, 2015 at 2:17 PM, Hal Finkel <hfinkel at anl.gov> wrote: > ----- Original Message ----- > > From: "Francois Pichet" <pichet2000 at gmail.com> > > To: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu> > > Sent: Sunday, February 22, 2015 5:34:11 PM > > Subject: [LLVMdev] Question about shouldMergeGEPs in

Hi all, > If I read the standard correctly, the properties of these address spaces can > be fully captured by defining the relationship between every pair of address > spaces (disjoint, identical, subset/superset). > > I think it would make sense to make these relationships backend/platform > specific, but for clang and the optimization passes to properly work with > address

A On 3/21/06, Michael McCracken <michael.mccracken at gmail.com> wrote: > On 3/21/06, Chris Lattner <sabre at nondot.org> wrote: > > On Mon, 20 Mar 2006, Michael McCracken wrote: > > > > > Hi, I'm trying to access an analysis pass from the Inliner pass, and > > > I'm having a lot of trouble getting that to work - I can verify that > >

/Volumes/mrs5/net/llvm/llvm/lib/Transforms/Scalar/ InstructionCombining.cpp: In member function ‘llvm::Instruction*<unnamed>::InstCombiner::visitAnd (llvm::BinaryOperator&)’: /Volumes/mrs5/net/llvm/llvm/lib/Transforms/Scalar/ InstructionCombining.cpp:3597: warning: ‘RHSCC’ may be used uninitialized in this function /Volumes/mrs5/net/llvm/llvm/lib/Transforms/Scalar/

Hi all, I've been fiddling around with debug info generated by clang, with the goal of propagating line number info to our custom backend (which is not an llvm backend, but does use llvm IR as its input). I've created a small pass which strips all debug info except for stop points, which are currently the only things we're interested in. Leaving only stop points in actually works

Hello all, I have evaluated the compile-time and execution-time performance of Polly canonicalization passes. Details can be referred to http://188.40.87.11:8000/db_default/v4/nts/recent_activity. There are four runs: pollyBasic (run 45): clang -O3 -Xclang -load -Xclang LLVMPolly.so pollyNoGenSCEV (run 44): clang -O3 -Xclang -load -Xclang LLVMPolly.so -mllvm -polly -mllvm -polly-codegen-scev

On Jul 23, 2008, at 8:08 AM, Matthijs Kooijman wrote: > Hi Chris, > >> I just meant -O3 as an example. I'd expect all -O levels to have the >> same behavior. -O3 may run passes which are more "lossy" than -O1 >> does though, and I'd expect us to put the most effort into making >> passes run at -O1 update debug info. > I'm not really sure

Hi Chris, > I just meant -O3 as an example. I'd expect all -O levels to have the > same behavior. -O3 may run passes which are more "lossy" than -O1 > does though, and I'd expect us to put the most effort into making > passes run at -O1 update debug info. I'm not really sure that you could divide passes into "lossy" and "not so lossy"

Hi all, The InstructionCombining pass causes alignment of globals to be ignored. I've attached a replacement of Fibonacci.cpp which reproduces this (I used 2.3 release). Here's the x86 code it produces: 03C20019 movaps xmm0,xmmword ptr ds:[164E799h] 03C20020 mulps xmm0,xmmword ptr ds:[164E79Ah] 03C20027 movaps xmmword ptr ds:[164E799h],xmm0 03C2002E

I think it would make sense for (1) and (2). I am not sure if (3) is feasible in instcombine. (I am not too familiar with LoopInfo) For the Octasic's Opus platform, I modified shouldMergeGEPs in our fork to: if (GEP.hasAllZeroIndices() && !Src.hasAllZeroIndices() && !Src.hasOneUse()) return false; return Src.hasAllConstantIndices(); // was return false;

Does LLVM hoist bounds checks out of inner loops? -- Dr Jon D Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/products/?e

Hi Sanjay, 2017-01-30 22:22 GMT+01:00 Sanjay Patel <spatel at rotateright.com>: > My minimal patch idea is to ease the restriction in ShouldChangeType > because i1 is special. I tried the patch below, and it works on the > example...and nothing in 'make check' failed. :) > Yeah, that would work for me as well, I just wasn't sure about the implications that has.

If you're able to reproduce the infinite loop with -O3 then you should be able to dump out the IR that causes `opt -instcombine` to infloop, unless the bug is truly esoteric (e.g. only caused by a specific use-list ordering). Maybe take a closer look at the output from `opt -print-before-all -O3`? Alternatively you can use bugpoint to minimize the IR to get a small reproducer that causes