similar to: [LLVMdev] Get Different Result for ScalarEvolution through ModulePass and FunctionPass

Which cases does this pass handle which aren't otherwise optimized out by passes like GlobalValueNumbering or DeadCodeElimination? Thanks, Jake VanAdrighem On Thu, Sep 10, 2015 at 2:35 PM, Steve King <steve at metrokings.com> wrote: > Hello LLVM, > It seems this thread has gone cold. Is there some low risk way for > the community to take the new pass for a test drive? >

On Wed, Sep 2, 2015 at 5:36 AM, James Molloy <james at jamesmolloy.co.uk> wrote: > Hi, > > Coremark really isn't a good enough test - have you run the LLVM test suite > with this patch, and what were the performance differences? For the test suite single source benches, the 235 tests improved performance, 2 regressed and 705 were unchanged. That seems very optimistic.

Hi, In my work applying -flto to Chrome, I need to set some names to be skipped by the InternalizePass; otherwise, the linking stage fails (i.e., when building the chrome binary). In the past, I had a tiny patch that I hadn't submitted to LLVM: it was something like: Index: Internalize.cpp =================================================================== --- Internalize.cpp (revision

Hi Andrew, The issue below refers to LSR, so I'll appreciate your feedback. It also refers to instruction combining and might impact backends other than X86, so if you know of others that might be interested you are more than welcome to add them. Thanks, Anat _____________________________________________ From: Shemer, Anat Sent: Tuesday, February 18, 2014 15:07 To: 'llvmdev at

On 8/8/2017 1:37 PM, Friedman, Eli wrote: > On 8/8/2017 10:22 AM, Geoff Berry via llvm-dev wrote: >> Hi all, >> >> I'm looking into resolving a FIXME in the LoopDataPrefetch (and FalkorMarkStridedAccesses) pass by marking both of these passes as preserving the ScalarEvolution analysis. Unfortunately, when this change is made, LSR will generate different code. One of the

> Of course, and the point is that, for example, on x86_64, the zext here is free. I'm still trying to understand the problem... > > In the example you provided in your previous e-mail, we choose the solution: > > `GEP @Global, zext(V)` -> `GEP (@Global + zext VStart), {i64 0,+,1}` > `V` -> `trunc({i64 0,+,1}) + VStart` > > instead of the actually-better

Hi all, I'm looking into resolving a FIXME in the LoopDataPrefetch (and FalkorMarkStridedAccesses) pass by marking both of these passes as preserving the ScalarEvolution analysis. Unfortunately, when this change is made, LSR will generate different code. One of the root causes seems to be that SCEV will return different nsw/nuw flags for the same Value, depending on what order the

This is related to an issue in loop strength reduction [1] that I've been trying to fix on and off for a while. [1] has a more detailed description of the issue and an example, but briefly put, I want LSR to consider formulae that have "Zext T" as base and/or scale registers, and to appropriately rate such formulae. My first attempt[2] at fixing this was buggy and had to be

I come across a situation that I am having a hard time to understand. When I compile the following code : char *tst( char *dest, const char *src, unsigned int len ) { for (int i=0 ; i<len ; i++) { dest[i] = src[i]; } return dest; } Clang generates this for the ‘for’ body: for.body: ; preds = %for.cond %arrayidx = getelementptr inbounds i8,

> I don't understand why you want to factor out the information, > exactly. It seems like what you need is a function like: > > unsigned getMinLeadingZeros(const SCEV *); > > then, if you want to get the non-extended expression, you can just > apply an appropriate truncation. I assume, however, that I'm missing > something. The problem is not about how to codegen

> To back up for a second, how much of this is self-inflicted damage? > IndVarSimplify likes to preemptively widen induction variables. Is > that why you have the extensions here in the first place? In the specific example I was talking about the zext came from our frontend (our FE used to insert these extensions for reasons that are no longer relevant). But you can easily get the same

While rototilling packet.c, I did some looking at cipher_encrypt in cipher.c. It ends up that for SSH_CIPHER_NONE in cipher_encrypt, it uses memcpy. However, it also appears that dest and src can be equal in cipher_encrypt. On most sane libc implementations, memcpy == memmove. However, ANSI C makes no such guarantee, and some implementations out there are bound to try to optimize memcpy

Hi all, I have data from an experiment with 3 independent variables, 2 are within and 1 is between. In addition to the dependent variable, I have a covariate that is a single measure per subject. Below I provide an example generated data set and my approach to implementing the ANCOVA. However the output confuses me; why does the covariate only appear in the first strata? Presumably it should

Mai, Haohui wrote: > Hi all, > > I'm working on a project which tries to prove an access to an array is > safe. For example, > > int foo(int s) { > int * p = malloc(s * sizeof int); > ... > int q = p[s - 2]; > } > > then the access of p[s - 2] always stays in bound. > > I implemented a prototype using the Scalar Evolution pass. Here are the

I have data from a design in which items are completely nested within subjects. Subject is the only second-level factor, but I have multiple first-level factors (IVs). Say there are 2 such independent variables that I am interested in. What is the proper syntax to fit a mixed-effects model with a by-subject random intercept, and by-subject random slopes for both the 2 IVs? I can

Hey LLVMDev, I'm working on a ModulePass that uses ScalarEvolution along with several other analyses. After some debugging, it looks to me like ScalarEvolutionWrapperPass does not handle memory correctly for this case. Here's my current understanding of the problem. ScalarEvolutionWrapperPass maintains a unique_ptr to a ScalarEvolution. Calling getSE() dereferences this pointer.

Nick, It might be a little bit difficult to handle SMax correctly. But is it possible to reduce A+(-A) to 0 in SAddExpr? Haohui On Wed, 2009-06-24 at 01:05 -0500, Mai, Haohui wrote: > On Tue, 2009-06-23 at 22:55 -0700, Nick Lewycky wrote: > > Mai, Haohui wrote: > > > Hi all, > > > > > > I'm working on a project which tries to prove an access to an array

Mai, Haohui wrote: > Nick, > > It might be a little bit difficult to handle SMax correctly. But is it > possible to reduce A+(-A) to 0 in SAddExpr? Yes, it should already do that. Here's a quick test I wrote up: $ cat x.ll define i8 @test(i8 %x) { %neg = sub i8 0, %x %sum = add i8 %x, %neg ret i8 %sum } $ llvm-as < x.ll | opt -analyze

On Tue, 2009-06-23 at 22:55 -0700, Nick Lewycky wrote: > Mai, Haohui wrote: > > Hi all, > > > > I'm working on a project which tries to prove an access to an array is > > safe. For example, > > > > int foo(int s) { > > int * p = malloc(s * sizeof int); > > ... > > int q = p[s - 2]; > > } > > > > then the access

Thanks for the suggestions Vedant. Synthetic debug info is an interesting idea that sounds worthwhile. Could this be implemented as a “wrapper” pass that automatically decorates debug info before and after a specific pass run in opt (or pipeline of passes)? It might be useful to be able to easily enable this for a wide range of tests without having to manually modify each run line, perhaps as an