similar to: Why LLVM cannot optimize this?

Hi, Yes SCEV is pretty limited on this aspect. This kind of code can trigger LLVM to explode in time/memory: https://llvm.org/bugs/show_bug.cgi?id=18606 <https://llvm.org/bugs/show_bug.cgi?id=18606> See also this llvm-dev thread: SCEV implementation and limitations, do we need "pow"? : http://lists.llvm.org/pipermail/llvm-dev/2014-February/070062.html CC: Sanjoy who may have an

Hi, I'm working on a slow-compile problem caused by SCEV (PR28830), and I need your suggestions on how to fix it. The loop below causes ScalarEvolution::getMulExpr to hang. int get(unsigned n) { unsigned i, j, mult = 1; for (i = 0; i < 1; i++) { for (j = 0; j < 30; j++) { mult *= n++; } } return mult; } the inner loop is completed unrolled

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:

Hi Nick, Thanks for looking into it. I have tried that as well but it didn't worked. "AddExpr->getOperand(0))" node is: " (4 * (sext i32 {2,+,2}<%for.body4> to i64))<nsw>" When I cast this to "SCEVAddRecExpr" it returns NULL. Regards, Ashutosh -----Original Message----- From: Nick Lewycky [mailto:nicholas at mxc.ca] Sent: Thursday, March 19,

Hi, I'm trying to cast one of the SCEV node to "SCEVAddRecExpr". Every time cast return NULL, and I'm unable to do this. SCEV Node: ((4 * (sext i32 {2,+,2}<%for.body4> to i64))<nsw> + %var)<nsw> Casting: const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SCEVNode); 'var' is of type float pointer (float*). Without 'sext' it works, but

Hi, I wonder how many of you are familiar with scalar evolution pass. I met a problem regarding to the SCEVAddRecExpr. Say for the code: const int N = 100; int a[N]; for(int i=0;i<N;i++) a[i] = 0; For the access of a[i], the pass will transform this a[i] to a SCEVAddRecExpr <@a, +, sizeof(int)><BB_Name>, which means the access of the array `a' starts from the address `a' and

Hi, You may try function "getSCEVAtScope" of the ScalarEvolution analysis: /// getSCEVAtScope - Return a SCEV expression for the specified value /// at the specified scope in the program. The L value specifies a loop /// nest to evaluate the expression at, where null is the top-level or a /// specified loop is immediately inside of the loop. /// /// This method can be used to compute

Sorry typo in test case, Please ignore previous mail. Consider below case: for (j=1; j < itr; j++) { - - - - for (i=1; i < itr; i++) { { temp= var[i << 1]; - - - - - } } In the above example, we are unable to get "SCEVAddRecExpr" for "var[i << 1]" Its "SCEVAddRecExpr" is computable in *Outer Loop* I

How do you generate a SCEVAddRecExpr from a SCEV? It tried dyn_casting and it seems like that the SCEV returned by getSCEV is not a SCEVAddRecExpr. Thanks On Fri, Sep 30, 2016 at 4:16 PM, Friedman, Eli <efriedma at codeaurora.org> wrote: > On 9/30/2016 12:16 PM, Charith Mendis via llvm-dev wrote: > >> >> Hi all, >> >> What is the best way to get the symbolic

Hi there, I've got this vector: -84 -87 -90 -90 -89 -86 NA NA NA NA NA NA NA NA NA NA NA NA -96 -99 -100 -99 -96 -92 -89 -87 -87 -88 -90 -92 -94 -95 -96 -97 -97 -97 -96 -95 Is there a function in R which replaces the NAs with "interpolated" values between -86 and -96? Thanks, Sven

Hi all, What is the best way to get the symbolic expression for an address calculation in llvm specially when memory addresses are calculated within a loop. Use case: I want to know what loop induction variables are used for a particular address calculation and in what symbolic context. Thereby, I want to identify which stores and loads will be contiguous in memory if I unroll each of the

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>

> On Mar 20, 2015, at 8:02 PM, Nema, Ashutosh <Ashutosh.Nema at amd.com> wrote: > > > Yes, this is what I was proposing above and here ;): > Thanks Adam it’s for confirming J NP :). > > > No, not hasLoopInvariantStore but hasAccessToLoopInvariantAddress. > Its only for invariant stores[not loads], Using ‘hasLoopInvariantStore’ (or a name with invariant store)

Hi Fellows, The goal is to find the induction variable for a loop, where the induction variable increments with the multiplication, division or shift operations, like this one: sz = 8; do { ... ... sz = sz / 2; } while (sz) Is SCEV capable of detecting the induction variable 'sz' in this case? The code snippet I am using to solve the problem is for each basic-block in a

I now understand that IndVarSimplify.cpp is capable of reproducing array references when the pointer initialization from the array address is found inside the immediately enclosing loop, such that in the following code: int A[20000], B[100], Z; int main() { int i, j, *a, *b; for ( a = &A[0], i = 0; i != 200; i++ ) for ( b = &B[0], j = 0; j != 100; j++

I am not yet a R user but I will be soon. I am looking for the R command and syntax to compute the roots of Bessel function i.e. computing the z values that lead to Jnu(z)=0 where J is a Bessel function or order nu. May You help me ? thanks in advance. Dr Catherine COUTAND Institut National de la Recherche Agronomique (INRA) umr Physiologie Int?grative de l'Arbre Fruitier et Forestier

Hello, I'm studying how the SCEV analyzis works and how to use it and I could not create an example where the SCEV analyzis identifies an expression as "SCEVAddRecExpr". Aren't the expressions below the kind of pattern that should be represented as a "AddRecExpr" ? SCEV: (1 + (2 * %3) or SCEV: (%1 + (2 * %3) or SCEV: (%1 + (%2 * %3) In my experiments they are

I've been doing some digging in this area (scev, wrapping arithmetic), learning as much as I can, and have reached a point where I'm fairly confused about the semantics of nuw in scalar evolution expressions. Consider the following program: define void @foo(i32 %begin) { entry: br label %loop loop: %idx = phi i32 [ %begin, %entry ], [ %idx.dec, %loop ] %idx.dec = sub nuw i32

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

I am testing vectorization on the following test case: float x[1024], y[1024]; void myloop1() { for (long int k = 0; k < 512; k++) { x[2*k] = x[2*k]+y[k]; } } Vectorization failed due to "unsafe dependent memory operation". I traced the LoopAccessAnalysis.cpp and found the reason is the NoWrapFlag for SCEVAddRecExpr is not set and consequently the