similar to: [LLVMdev] Hint about how to contribute to LLVM

Displaying 20 results from an estimated 2000 matches similar to: "[LLVMdev] Hint about how to contribute to LLVM"

2011 Mar 09
1
[LLVMdev] Is InstructionSimplify still a good place to contribute?
I'm looking for some opportunities to contribute to the LLVM core without too big of a learning curve. The open projects page<http://llvm.org/OpenProjects.html#misc_imp>suggests moving logic from the instruction combining transformation to the InstructionSimplify analysis. But it looks like some work has been done there since the projects page was last edited. Is there more benefit to
2015 Sep 24
3
Comparing stack addresses and function args (Was: [llvm] r174131 - Add a comment explaining an unavailable optimization)
Apologies if this has come up before. I couldn't find any previous discussion, but I did find this commit. I was wondering why LLVM cannot optimize this code (which GCC does optimize): int f(int *p) { int x; return p == &x; } it would seem that this must always return 0. (This occurs as a self-assignment check in the code I was looking at; I was hoping we could fold that check away.)
2016 Jul 20
2
Hitting assertion failure related to vectorization + instcombine
Hi folks, I'm hitting the below assertion failure when compiling this small piece of C code (repro.c, attached). My command line is: bin/clang --target=aarch64-linux-gnu -c -O2 repro.c clang is built from top of trunk as of this morning. It only happens at -O2, and it doesn't happen with the default target (x86_64). I tried to reproduce using just 'llc -O2' but didn't
2015 Sep 24
2
Comparing stack addresses and function args (Was: [llvm] r174131 - Add a comment explaining an unavailable optimization)
On Thu, Sep 24, 2015 at 12:06 PM, Aaron Ballman <aaron at aaronballman.com> wrote: > On Thu, Sep 24, 2015 at 2:42 PM, Hans Wennborg <hans at chromium.org> wrote: >> I was wondering why LLVM cannot optimize this code (which GCC does optimize): >> >> int f(int *p) { int x; return p == &x; } >> >> it would seem that this must always return 0. (This
2016 Jul 25
2
Hitting assertion failure related to vectorization + instcombine
Sure. David, what do you think about merging this to 3.9? Sanjay: are you saying I'd just apply that diff to InstructionSimplify.cpp, not InstCombineSelect.cpp? On Fri, Jul 22, 2016 at 7:08 AM, Sanjay Patel <spatel at rotateright.com> wrote: > Hi Hans - > > Yes, I think this is a good patch for 3.9 (cc'ing David Majnemer as code > owner). The functional change was
2016 Jul 20
2
Hitting assertion failure related to vectorization + instcombine
Thanks for notifying me. Yes, this was a recent change. Taking a look now. On Wed, Jul 20, 2016 at 1:49 PM, Michael Kuperstein <mkuper at google.com> wrote: > +Sanjay, who touched this last. :-) > > On Wed, Jul 20, 2016 at 12:44 PM, Ismail Badawi (ibadawi) via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> Hi folks, >> >> I'm hitting the
2016 Jul 27
0
Hitting assertion failure related to vectorization + instcombine
David, Sanjay: ping? On Mon, Jul 25, 2016 at 11:07 AM, Hans Wennborg <hans at chromium.org> wrote: > Sure. David, what do you think about merging this to 3.9? > > Sanjay: are you saying I'd just apply that diff to > InstructionSimplify.cpp, not InstCombineSelect.cpp? > > On Fri, Jul 22, 2016 at 7:08 AM, Sanjay Patel <spatel at rotateright.com> wrote: >> Hi
2015 Sep 25
2
Comparing stack addresses and function args (Was: [llvm] r174131 - Add a comment explaining an unavailable optimization)
On 09/24/2015 06:04 PM, Hans Wennborg wrote: > I tried your patch on a Clang build to see if it would fire. It > reduced the size of a bootstrap with 8500 bytes. Not huge, but it > seems like a nice improvement. And maybe it could be made more > powerful: not just checking if the address is a param or alloca, but > an address based on such values. Yeah, I realized after posting that
2016 Jul 28
1
Hitting assertion failure related to vectorization + instcombine
LGTM On Wednesday, July 27, 2016, Hans Wennborg <hans at chromium.org> wrote: > David, Sanjay: ping? > > On Mon, Jul 25, 2016 at 11:07 AM, Hans Wennborg <hans at chromium.org > <javascript:;>> wrote: > > Sure. David, what do you think about merging this to 3.9? > > > > Sanjay: are you saying I'd just apply that diff to > >
2015 Sep 24
3
Comparing stack addresses and function args (Was: [llvm] r174131 - Add a comment explaining an unavailable optimization)
I threw together a patch which implements this (attached.) If we decide that this is actually a legal transform, I'm happy to post this for review. In addition to the version proposed here, I also implemented a case where a trivially escaped alloca's address is not equal to any other value. I believe both are valid, but we should confirm. Philip On 09/24/2015 02:34 PM, Aaron
2016 Jul 22
2
Hitting assertion failure related to vectorization + instcombine
Sanjay: let me know if this is something that will apply to 3.9. Thanks, Hans On Wed, Jul 20, 2016 at 5:59 PM, Sanjay Patel via llvm-dev <llvm-dev at lists.llvm.org> wrote: > Quick update - the bug existed before I refactored that chunk in > InstSimplify with: > https://reviews.llvm.org/rL275911 > > In fact, as discussed in https://reviews.llvm.org/D22537 - because we have a
2010 Nov 11
5
[LLVMdev] Simplifying selects + arm stuff
<cc'ing llvmdev> On Nov 10, 2010, at 6:38 AM, Duncan Sands wrote: > Hi Chris, in commit 12800 you introduced the following transform: > > Implement select.ll:test12* > > This transforms code like this: > > %C = or %A, %B > %D = select %cond, %C, %A > into: > %C = select %cond, %B, 0 > %D = or %A, %C > > Since B is often a
2017 Mar 30
2
InstructionSimplify: adding a hook for shufflevector instructions
As Sanjay noted in D31426<https://reviews.llvm.org/D31426#712701>, InstructionSimplify is missing the following simplification: This function: define <4 x i32> @splat_operand(<4 x i32> %x) { %splat = shufflevector <4 x i32> %x, <4 x i32> undef, <4 x i32> zeroinitializer %shuf = shufflevector <4 x i32> %splat, <4 x i32> undef, <4 x i32>
2014 Aug 27
2
[LLVMdev] Bug 16257 - fmul of undef ConstantExpr not folded to undef
Hi Duncan, Thank you a lot for your time to provide that great and informative explanation. Now the "undef" logic makes much more sense for me. >> /You are wrong to say that "div undef, %X" is folded to "undef" by InstructionSimplify, it is folded to zero./ My mistake. I meant to say "*f****div* undef, %X" is folded to "undef" (not
2014 Aug 27
3
[LLVMdev] Bug 16257 - fmul of undef ConstantExpr not folded to undef
Duncan, > Hi Oleg, > >> >> /This is either a mistake, or a decision that in LLVM IR snans >> are always >> considered to be signalling. / >> Yes, this seems to be an agreement to treat "undef" as a SNaN for >> "fdiv". > > "undef" is whatever bit pattern you want it to be, i.e. the compiler > can assume it is any
2016 Jun 12
2
Regarding a TODO in InstructionCombining
Hi, This is regarding a TODO mentioned in getIdentityValue function in InstructionCombining.cpp file. //TODO: We can handle other cases e.g. Instruction::And, Instruction::Or etc. I wanted to know what could be the use cases of implementing these. When I tried implementing these and wrote test cases for the same, the test cases would be optimized in InstructionSimplify before hitting the code
2013 Jan 15
2
[LLVMdev] [cfe-dev] no-alias generated as result of restrict function arguments
On Wed, Dec 12, 2012 at 01:59:55PM -0800, Dan Gohman wrote: > The bug here isn't in clang's use of noalias or in BasicAliasAnalysis' > implementation of noalias; it's in the code that's optimizing the > icmp. Let's come back to this. The attached patch decouples InstSimplify from the alias analysis and provides the conservative logic for when pointers are not
2016 Mar 17
2
How to let LLVM handle undefined behavior more gracefully?
Hi, There are cases where LLVM is able to detect some UB but clang is not. For example, unsigned int foo(unsigned int x) { int ret = 0; for(int i = 0; i <= 32; ++i) ret += x >> i; return ret; } When the loop is unrolled, LLVM InstructionSimplify will catch it and return a UNDEF value. How can we let LLVM report some warning message to help developers correct the error?
2014 Aug 26
2
[LLVMdev] Bug 16257 - fmul of undef ConstantExpr not folded to undef
Hi Duncan, Thank you for your comment to the bug 16257. I am new to LLVM, so not all the aspects of LLVM's /"undef"/ seem clear to me yet. I read and understood the examples from the LLVM documentation: http://llvm.org/docs/LangRef.html#undefined-values However, those examples do not cover all of the possible contexts where /"undef"/ can appear. E.g., I can't
2020 Nov 16
1
Complex proposal v3 + roundtable agenda
On Fri, Nov 13, 2020 at 3:01 PM Florian Hahn <florian_hahn at apple.com> wrote: > > > > On Nov 12, 2020, at 21:36, Cameron McInally <cameron.mcinally at nyu.edu> wrote: > > On Thu, Nov 12, 2020 at 2:47 PM Florian Hahn <florian_hahn at apple.com> wrote: > > There certainly is some pieces around the edges that will need adjusting or become obsolete, but I