similar to: [LLVMdev] SIV tests in LoopDependence Analysis, Sanjoy's patch

Hi Hal, Preston! Sorry for the delay! Got busy with some offline work. I've worked on my previous code to calculate direction and distance vectors whenever possible (strong SIV, basically). I think the current code is much clearer and would like your opinions on it. I have attached the patch and also pushed to the github repo I mentioned [1]. Thanks! [1]

Hi Sanjoy, Reading through LoopDependenceAnalysis::analyseStrongSIV(), I noticed one problem and one confusion. My confusion related to your naming of the two instructions as A and B. It's consistent all through LoopDependenceAnalysis. I'd prefer something like source and destination, so I can keep track of which is which. It didn't matter so much when you were simply proving or

Hi, Here is a preliminary (monolithic) version you can comment on. This is still buggy, however, and I'll be testing for and fixing bugs over the next few days. I've used your version of the strong siv test. Thanks! -- Sanjoy Das. http://playingwithpointers.com -------------- next part -------------- A non-text attachment was scrubbed... Name: patch.diff Type: application/octet-stream

Hi Sanjoy & Hal, Looking at LoopDependenceAnalysis::analyzeZIV ... I don't understand much about SCEV, but the code seems inadequate. Consider these three examples: int a = ...; // we can't be sure of the relationship between a and b int b = ...; // perhaps they are parameters, or the result of I/O for (int i = 0; i < n; i++) { v[a][i] = ...; v[a + 1][i] = ...; } for (int i

Hi, When I write various test cases and explore how they're handled by the code in LoopDependenceAnalysis::analysePair, I'm surprised. This loop collects pairs of subscripts from the source and destination refs. * // Collect GEP operand pairs (FIXME: use GetGEPOperands from BasicAA), adding* * // trailing zeroes to the smaller GEP, if needed.* * GEPOpdsTy destOpds, srcOpds;* *

Hi Preston, Thanks for the feedback! > In LoopDependenceAnalysis::AnalyzePair, what's going to happen if we > have something like this > > for (i = 0; i < n; i++) > for (j = 0; j < n; j++) > A[i][j]++; > > versus > > for (i = 0; i < n; i++) > for (j = 0; j < n; j++) > A[j][i]++; I think this can be fixed by ordering the subscripts

On Sat, Apr 21, 2012 at 6:08 AM, Sanjoy Das <sanjoy at playingwithpointers.com> wrote: > > Sorry for having been quiet for so long, I have my university exams > going on, and will be able to contribute only after the coming Friday. Gents, While you've been fooling around with exams, I have been focused with laser-like intensity, or something... Here are new versions of 4 SIV

Hi Sanjoy, Here's a version of Banerjee and Wolfe's Exact SIV test: https://sites.google.com/site/parallelizationforllvm/weak-siv-test It assumes you've already filtered out the easy cases handled by ZIV, strong SIV, etc. I'm not confident about my uses of APInt. If you have any comments, I'd love to hear them. Thanks, Preston On Thu, Apr 12, 2012 at 5:14 AM, Sanjoy Das

Hi Sanjoy, I reworked the code for analyzeStrongSIV to fix a couple of mistakes, plus squeeze all the advantage possible from the symbolic manipulation provided by the SCEVs. It's sketched out here: https://sites.google.com/site/parallelizationforllvm/strong-siv-test Does it makes sense to you? Thanks, Preston On Thu, Apr 5, 2012 at 4:09 PM, Preston Briggs <preston.briggs at

On Wed, 18 Apr 2012 18:16:47 -0700 Preston Briggs <preston.briggs at gmail.com> wrote: > Hi Sanjoy, > > Here's a version of Banerjee and Wolfe's Exact SIV test: > https://sites.google.com/site/parallelizationforllvm/weak-siv-test > It assumes you've already filtered out the easy cases handled by ZIV, > strong SIV, etc. > > I'm not confident about my

Hi all, Sorry for having been quiet for so long, I have my university exams going on, and will be able to contribute only after the coming Friday. Thanks! -- Sanjoy Das http://playingwithpointers.com

On Mon, 14 May 2012 11:46:02 -0700 Preston Briggs <preston.briggs at gmail.com> wrote: > On Sat, Apr 21, 2012 at 6:08 AM, Sanjoy Das > <sanjoy at playingwithpointers.com> wrote: > > > > Sorry for having been quiet for so long, I have my university exams > > going on, and will be able to contribute only after the coming > > Friday. > > Gents, >

Hi Sanjoy, I wondered: >> In LoopDependenceAnalysis::AnalyzePair, what's going to happen if we >> have something like this >> >> for (i = 0; i < n; i++) >>   for (j = 0; j < n; j++) >>     A[i][j]++; >> >> versus >> >> for (i = 0; i < n; i++) >>   for (j = 0; j < n; j++) >>     A[j][i]++; > I think this

Preston Briggs wrote: > On Sat, Apr 21, 2012 at 6:08 AM, Sanjoy Das > <sanjoy at playingwithpointers.com <mailto:sanjoy at playingwithpointers.com>> > wrote: > > > > Sorry for having been quiet for so long, I have my university exams > > going on, and will be able to contribute only after the coming Friday. > > Gents, > > While you've been

> > Here's a version of Banerjee and Wolfe's Exact SIV test: > > https://sites.google.com/site/parallelizationforllvm/weak-siv-test > > It assumes you've already filtered out the easy cases handled by ZIV, > > strong SIV, etc. > > > > I'm not confident about my uses of APInt. If you have any comments, > > I'd love to hear them. >

On Mon, May 14, 2012 at 1:30 PM, Hal Finkel <hfinkel at anl.gov> wrote: > Can you explain this comment: > > With minor algebra, this test can also be used for things like [c1 + > > a1*i + a2*j][c2]. It's really too simple to deserve mention... Given a subscript pair, [c1 + a1*i + a2*j] and [c2], we can test for dependence using the RDIV test by rewriting as [c1 + a1*i]

On Mon, 14 May 2012 13:54:19 -0700 Preston Briggs <preston.briggs at gmail.com> wrote: > On Mon, May 14, 2012 at 1:30 PM, Hal Finkel <hfinkel at anl.gov> wrote: > > > Can you explain this comment: > > > With minor algebra, this test can also be used for things like > > > [c1 + a1*i + a2*j][c2]. > > It's really too simple to deserve mention...

On Thu, 15 Mar 2012 09:57:00 -0700 Preston Briggs <preston.briggs at gmail.com> wrote: > Shanmukha Rao wrote: > > I am using LLVM for implementing LoopFission pass. > > I am using LoopPass. > > I know that for checking circular dependency in loop I have to use > > LoopDependenceAnalysis > > > > This is what i want to do. > >         for(int i =

On Mon, May 14, 2012 at 2:14 PM, Hal Finkel <hfinkel at anl.gov> wrote: >> > One thing that I would like to mention is that 'use' here should >> > also include user feedback. This means being able to pass >> > information back to the frontends about which loops are being >> > effectively analyzed, and for loops that are not, why not. >>

Shanmukha Rao wrote: > I am using LLVM for implementing LoopFission pass. > I am using LoopPass. > I know that for checking circular dependency in loop I have to use LoopDependenceAnalysis > > This is what i want to do. >         for(int i = 0; i< n ; i++){ > s1 : a[i] = a[i] + x[i]; > s2 : x[i] = x[i+1] + i*2 ; > } > >