search for: gvn

Displaying 20 results from an estimated 931 matches for "gvn".

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2011 May 03
3
[LLVMdev] GVN Infinite loop
Hi, GVN seems to be running in an infinite loop on my example. I have attached the output of one iteration. I cant seem to reduce the testcase either. Any pointers to how to reduce the test case. THanks, Arushi GVN iteration: 8 GVN WIDENED LOAD: %0 = load i8* getelementptr inbounds (%struct.CHESS_POSI...
2011 May 04
0
[LLVMdev] GVN Infinite loop
On May 3, 2011, at 3:25 PM, Arushi Aggarwal wrote: > Hi, > > GVN seems to be running in an infinite loop on my example. I have attached the output of one iteration. I cant seem to reduce the testcase either. > > Any pointers to how to reduce the test case. Bugzilla can reduce testcases that cause infinite loops (it has a -timeout flag), I'd try it....
2016 Nov 16
7
[RFC] NewGVN
...s/code are from Daniel Berlin (with a minor overhaul/splitting into submittable patches from me). The code has been around for a while (2012 or before), and we think it's getting ready to be committed upstream. ### Motivation To put things into context: my personal motivation for having a new GVN/PRE algorithm is LTO. It's not a secret that LLVM is getting slower and slower release after release, as Rafael discovered/pointed out in March [1] (and probably many others found out). I personally took a shot at profiling LTO on many internal/opensource applications (including clang itself) a...
2011 May 04
0
[LLVMdev] GVN Infinite loop
Mainline. ------------------------------ From: John Criswell Sent: Tuesday, May 03, 2011 8:34 PM To: Arushi Aggarwal Cc: LLVM Dev Subject: Re: [LLVMdev] GVN Infinite loop On 5/3/11 5:25 PM, Arushi Aggarwal wrote: Hi, GVN seems to be running in an infinite loop on my example. I have attached the output of one iteration. I cant seem to reduce the testcase either. Are you running with LLVM 2.9 or LLVM mainline? -- John T. Any pointers to how...
2017 Jan 13
4
Wrong code bug after GVN/PRE?
Hi, I've stumbled upon a case where I think gvn does a bad (wrong) optimization. It's a bit messy to debug though so I'm not sure if I should just write a PR about it a let someone who knows the code look at it instead. Anyway, for the bug to trigger I need to run the following passes in the same opt invocation: -sroa -instcombine...
2016 Nov 16
2
[RFC] NewGVN
On Wed, Nov 16, 2016 at 2:03 AM, David Chisnall via llvm-dev < llvm-dev at lists.llvm.org> wrote: > This is really great to see, as I’ve spent far too much of my life over > the past two years fighting with undocumented assumptions made by GVN. A > couple of quick questions about the new GVN, based on problems I’ve had > with the old one: > > Does it assume that it’s always safe to widen a load (or store) to a power > of two? I don't believe old gvn does widening any more, and new gvn certainly doesn't. > F...
2016 Feb 09
2
[GVN] same sequence of instructions in if and else branch
...uot;right thing" i mean it can hoist if you want and it can prove it will not extend the live range. Note that VBE (very busy expressions) is a code size optimization only. It does not save time. On Tue, Feb 9, 2016 at 12:26 PM, Daniel Berlin <dberlin at dberlin.org> wrote: > This GVN does not do that, this is correct. It is a very simple GVN. All > phi nodes are considered to have unique values. > GCC's GVN, and the one i'm developing for LLVM at > https://github.com/dberlin/llvm-gvn-rewrite does the right thing. > > > > On Tue, Feb 9, 2016 at 11:4...
2015 Dec 03
3
GlobalsAA from GVN
Hi James, Thanks for the help. From the log, I could infer that SLP vectorizer is not preserving alias analysis, preventing GVN from getting the info. Although the first function to get compiled has GlobalsAA available during GVN, rest of them do not as SLP vectorizer run on that function invalidates GlobalsAA which is a module pass. Is there a way to force re-computation of a particular analysis? As a side note, I didn...
2015 Dec 02
2
GlobalsAA from GVN
Hi, I've noticed that alias analysis queries arising from GVN do not use the results from GlobalsAA. The last call to AAResultsWrapperPass::runOnFunction() before GVN does not add GlobalsAAWrapperPass due to unavailability. This leads to the alias queries from GVN not having any globals mod-ref info. Is this a known issue? and is there any way to have global...
2010 Dec 02
2
[LLVMdev] Undefined symbol in Hello pass
On Thu, Dec 2, 2010 at 3:20 PM, Chris Lattner <clattner at apple.com> wrote: > > On Dec 2, 2010, at 3:13 PM, Scott Ricketts wrote: > >> The only Transforms check that fails is LLVM :: >> Transforms/GVN/null-aliases-nothing.ll >> >> Could that be related? > > running "opt -basicaa -gvn -S null-aliases-nothing.ll" should produce this output, what are you seeing? I get the same thing, except with 2 whitespaces of indent instead of 1.
2017 Feb 27
4
[Proposal][RFC] Epilog loop vectorization
...>>> these after the fact, then we should. >>>> >>>> +Danny >>>> >>>> Isn’t Extended SSA supposed to help with this? >>>> >>>> >>>> Yes, it will solve this with no issue already. GVN probably >>>> does already too. >>>> >>>> even if if you have >>>> >>>> if (a == b) >>>> if (a == c) >>>> if (a == d) >>>> if (a == e) >>>> if (a == g) >>...
2018 Apr 10
2
Miscompilation bugs in GVN.cpp and PromoteMemoryToRegister.cpp?
On Tue, Apr 10, 2018 at 10:28 AM, Friedman, Eli via llvm-dev < llvm-dev at lists.llvm.org> wrote: > On 4/9/2018 8:19 PM, Jeehoon Kang via llvm-dev wrote: > > Dear llvm-dev, > > > Hi! We're collecting mis-compilation bugs in gvn and mem2reg since > 3.7.1. Specifically, We're interested in bugs in the following files: > > llvm/lib/Transforms/Scalar/GVN.cpp > llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp > > > 3.7 was released over two years ago; there have been many bugfixes to both > GV...
2010 Dec 03
0
[LLVMdev] Undefined symbol in Hello pass
Here is the output of the test: ******************** FAIL: LLVM :: Transforms/GVN/null-aliases-nothing.ll (4084 of 5497) ******************** TEST 'LLVM :: Transforms/GVN/null-aliases-nothing.ll' FAILED ******************** Script: -- opt /Users/beresini/Desktop/workspace/downloads/llvm-2.8/test/Transforms/GVN/null-aliases-nothing.ll -gvn -S | FileCheck /Users/beresini/D...
2018 Apr 10
0
Miscompilation bugs in GVN.cpp and PromoteMemoryToRegister.cpp?
...t; > > On Tue, Apr 10, 2018 at 10:28 AM, Friedman, Eli via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> On 4/9/2018 8:19 PM, Jeehoon Kang via llvm-dev wrote: >> >> Dear llvm-dev, >> >> >> Hi! We're collecting mis-compilation bugs in gvn and mem2reg since >> 3.7.1. Specifically, We're interested in bugs in the following files: >> >> llvm/lib/Transforms/Scalar/GVN.cpp >> llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp >> >> >> 3.7 was released over two years ago; there have been m...
2016 Feb 09
2
[GVN] same sequence of instructions in if and else branch
...gt; Date: Tuesday, February 9, 2016 at 11:34 AM To: Taewook Oh <twoh at fb.com<mailto:twoh at fb.com>> Cc: "llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>" <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> Subject: Re: [llvm-dev] [GVN] same sequence of instructions in if and else branch And there's no PHI node after this that depends on the condition? -- Mats On 9 February 2016 at 19:30, Taewook Oh via llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote: Hello, I found that GVN do...
2017 Jan 13
2
Wrong code bug after GVN/PRE?
..., because they are pretty much crazytown. --Dan On Fri, Jan 13, 2017 at 10:31 AM, Friedman, Eli via llvm-dev < llvm-dev at lists.llvm.org> wrote: > On 1/13/2017 12:31 AM, Mikael Holmén via llvm-dev wrote: > >> Hi, >> >> I've stumbled upon a case where I think gvn does a bad (wrong) >> optimization. It's a bit messy to debug though so I'm not sure if I should >> just write a PR about it a let someone who knows the code look at it >> instead. >> >> Anyway, for the bug to trigger I need to run the following passes in the &...
2018 Apr 10
2
Miscompilation bugs in GVN.cpp and PromoteMemoryToRegister.cpp?
Dear llvm-dev, Hi! We're collecting mis-compilation bugs in gvn and mem2reg since 3.7.1. Specifically, We're interested in bugs in the following files: llvm/lib/Transforms/Scalar/GVN.cpp llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp We checked all reports in the LLVM bugzilla (https://bugs.llvm.org/), so I'd like to ask if you know any such a...
2015 Dec 03
2
GlobalsAA from GVN
...created a patch for the same, please review: http://reviews.llvm.org/D15185 >You can specifically insert it into the pass pipeline, but in this case, we should just fix SLP to preserve the analysis. @Hal, I tried doing this but it didn't seem to work. I added the GlobalsAA pass right before GVN but it didn't seem to help. In retrospect, looking at the way pass manager works, it looks like it wasn't of much use. Since GlobalsAA is a ModulePass, and FunctionPasses that are scheduled even later are run first, those FunctionPasses that invalidate it do so for good. I do not know if th...
2016 Jun 30
0
Optimizations hindered by GVN widening
Currently, the GVN optimization widens loads if the alignment permits it. There are some limitations that show up, as seen in example below: Initial IR: declare void @consume(i8) readonly define i8 @bar(i8* align 2 %a) { %1 = load i8, i8* %a %idx = getelementptr i8, i8* %a, i64 1 %2 = load i8, i8* %idx, alig...
2014 May 03
2
[LLVMdev] Testcases where GVN uses too much memory?
I've heard a few times, "GVN uses too much memory." The real fix is probably a rewrite of some sort, but that's not what this email is about. I have a few patches that should *incrementally* reduce its memory usage. Keyword being "should", because I haven't observed an improvement... in fact, I haven&...