similar to: [IndVarSimplify] Narrow IV's are not eliminated resulting in inefficient code

Hi Sanjoy, Thank you for looking into this! Yes, your patch does fix my larger test case too. My algorithm gets double performance improvement with the patch, as the loop now has a smaller instruction set and succeeds to unroll w/o any extra #pragma's. I also ran the LLVM tests against the patch. There are 6 new failures: Analysis/LoopAccessAnalysis/number-of-memchecks.ll

Dear All, Is the following patch to ScalarEvolution correct? It seems that without it, the enclosing for loop could skip over SCEVAddRecExpr's in the Ops[] array. -- John T. -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: scpatch URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20080222/3ff8edd7/attachment.ksh>

Hi folks, I'm trying to analyse this piece of IR: for.body: ; preds = %for.body, %entry %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ] %0 = shl nsw i64 %indvars.iv, 1 %arrayidx = getelementptr inbounds i32* %b, i64 %0 %1 = load i32* %arrayidx, align 4, !tbaa !1 %add = add nsw i32 %1, %I %arrayidx3 = getelementptr

On Nov 13, 2013, at 3:39 AM, Renato Golin <renato.golin at linaro.org> wrote: > Hi folks, > > I'm trying to analyse this piece of IR: > > for.body: ; preds = %for.body, %entry > %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ] > %0 = shl nsw i64 %indvars.iv, 1 > %arrayidx = getelementptr inbounds

On 16 November 2013 06:56, Andrew Trick <atrick at apple.com> wrote: > - getMulExpr constructs a new AddRec with NSW: > > Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW)); > const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags); > Hi Andrew, Thanks for looking at this. Clearing the flags here makes sense, but it's being too

Thanks for sharing the known problem. I think to solve the problem properly, we need to fully understand why that assumption about dominance is there and the implications of removing it. It would be good if you could be more specific about your idea of nullptr or SCEV_unknown (eg which function would return those values and when), but returning nullptr from getAddExpr or getSCEVAtScope may be

Hi, Thanks for the input. In my ptr_test.O1.ll, the two loops should fall into the last case due to loop rotations. And I think we should handle that case. I propose to check the dominance relation between loop predecessor blocks of the two loops if there is no dominance relation between their loop headers just like case three. The only thing I'm not pretty sure is that is there guarantee to

Hi Jimmy, It's good to know that the problem is not specific to the case I ran into. May be you can provide your example as well, since Philip seems to be interested in some specific examples. If the assertion in getAddrExpr is deemed necessary, then I think a condition check would be the next best solution as it helps client code guard against such cases and make alternative arrangements to

Hi, Recently I got a crash when I tried to analysis a program with ScalarEvolution AliasAnalysis(SCEV-AA for short). It turns out to be a (possibly) incorrect assertion inside the CompareSCEVComplexity routine. The simplest solution would be just remove that assertion but I also found that the surrounding logics on calculating SCEV cost seems to be incorrect either. Thus I want to discuss with

I'd like a value, call it Bottom, such that SE->getAddExpr(Bottom, X) => Bottom SE->getMulExpr(Bottom, X,) => Bottom isKnownPredicate(any, Bottom, X) => false etc. I can write code to make NULL work like I want, but it would be simpler if something was already defined. I'm wondering about SCEV::Unknown. The documentation suggests I could perhaps use it for a

Hello all, I wanted to get some feedback on this patch for ScalarEvolution. It addresses a performance problem I am seeing for simple benchmark. Starting with this C code: 01: signed char foo(void) 02: { 03: const int count = 8000; 04: signed char result = 0; 05: int j; 06: 07: for (j = 0; j < count; ++j) { 08: result += (result_t)(3); 09: } 10: 11: return result; 12: } I

On Sun, 7 Oct 2012 18:53:59 -0700 Preston Briggs <preston.briggs at gmail.com> wrote: > I'd like a value, call it Bottom, such that > > SE->getAddExpr(Bottom, X) => Bottom > SE->getMulExpr(Bottom, X,) => Bottom > isKnownPredicate(any, Bottom, X) => false > etc. > > > I can write code to make NULL work like I want, but it would be > simpler

Hello, I Have a question related to the RT check on pointers during Loop Access Analysis pass. There is a testcase with loop code that consist of 4 different memory operations referring two global objects of different address spaces. One from global constant (address space 4, addr_size = 64) and the other from local, LDS (address space 3, addr_size= 32). (Details of various address spaces

> I'm not following your example.  If you have two sibling loops with the same parent, one will frequently, but not always dominate the other.  Can you give a specific example of when forming a recurrence between two siblings (without one dominating the other), is useful? The situation can happen with guarded loops or with a user guard like below: if (c) { for (i = 0; i < n; i++)

Hi Stefanos, Attached the testcase. I tried to reduce it further, but the problem goes away when I remove the instructions further. There is a nested loop and the fault occurs while processing the inner loop (for.body) To reproduce the crash: opt -O3 testcase.ll -o out.ll > `groupChecks()` will only try to group pointers that are on the same alias set. If that’s true, the RT check

Hi Preston, I was wondering ... "Bottom" is a bit overloaded as far as terms go. Would SCEVNaN be a better name for this beast? Sameer. > -----Original Message----- > From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On > Behalf Of Sameer Sahasrabuddhe > Sent: Monday, October 08, 2012 9:16 AM > To: preston.briggs at gmail.com > Cc: LLVM

hi all, i have SCEVAddRec {{(32 + @edge.8265),+,32}<Loop0>,+,4}<Loop1> where Loop0 and Loop1 are brothers (loops at the same level of the loopnest), and Loop0 have a computable backedge taken count. when i call getSCEVAtScope({{(32 + @edge.8265),+,32}<Loop0>,+,4}<Loop1> , Loop1), it just give me a {{(32 + @edge.8265),+,32}<Loop0>,+,4}<Loop1>, instead of

Yes, I can get "SCEVAddRecExpr" from operands of "(sext i32 {2,+,2}<%for.body4> to i64)". So whenever SCEV cast to "SCEVAddRecExpr" fails, we have drill down for such patterns ? Is that the right way ? Regards, Ashutosh -----Original Message----- From: Nick Lewycky [mailto:nicholas at mxc.ca] Sent: Thursday, March 19, 2015 1:02 PM To: Nema, Ashutosh Cc:

On Tue, Sep 18, 2012 at 10:59 PM, Andrew Trick <atrick at apple.com> wrote: > > On Sep 18, 2012, at 8:21 PM, Preston Briggs <preston.briggs at gmail.com> > wrote: > > Given the following SCEV, > > *(sext i32 {2,+,1}<nw><%for.body> to i64)* > > > from the following C source, > > *void strong3(int *A, int *B, int n) {* > * for (int i =

Hi, I have a SCEV like this: {16,+,8}. Say that this came from a loop like: int64_t *p; for (int64_t i = 0; i < ...; ++i) p[i+2]... And assuming that I'm on a 64-bit machine. What I would like to do is normalize it like that, basically this: {2,+,1} i.e. map it to the index. Now, I tried to get the underlying element size of the pointer, then getUDivExpr(OriginalSCEV, ElementSize); But