similar to: Loop unrolling parameters

If count > MAX_UINT-4 your loop loops indefinitely with an increment of 4, I think. On Thu, Oct 13, 2016 at 4:42 PM, Charith Mendis via llvm-dev < llvm-dev at lists.llvm.org> wrote: > So, I tried unrolling the following simple loop. > > int unroll(unsigned * a, unsigned * b, unsigned *c, unsigned count){ > > for(unsigned i=0; i<count; i++){ > > a[i] =

Thanks for the explanation. But I am a little confused with the following fact. Can't LLVM keep vectorizable_elements as a symbolic value and convert the loop to say; for(unsigned i = 0; i < vectorizable_elements ; i += 2){ //main loop } for(unsigned i=0 ; i < vectorizable_elements % 2; i++){ //fix up } Why does it have to reason about the range of vectorizable_elements? Even

On 16/01/2014, 23:47 , Andrew Trick wrote: > > On Jan 15, 2014, at 4:13 PM, Diego Novillo <dnovillo at google.com > <mailto:dnovillo at google.com>> wrote: > >> Chandler also pointed me at the vectorizer, which has its own >> unroller. However, the vectorizer only unrolls enough to serve the >> target, it's not as general as the runtime-triggered

Hi all, Attached herewith is a simple vectorized function with loops performing a simple shuffle. I want all loops (inner and outer) to be unrolled by 2 and as such used -unroll-count=2 The inner loops(with k as the induction variable and having constant trip counts) unroll fully, but the outer loop with (j) fails to unroll. The llvm code is also attached with inner loops fully unrolled. To

I am starting to use the sample profiler to analyze new performance opportunities. The loop unroller has popped up in several of the benchmarks I'm running. In particular, libquantum. There is a ~12% opportunity when the runtime unroller is triggered. This helps functions like quantum_sigma_x (http://sourcecodebrowser.com/libquantum/0.2.4/gates_8c_source.html#l00149). The function accounts

I just wanted to add to Krzysztof's response. I'm not sure if you're referring to the case when a compile-time trip count loop is completely unrolled or for a loop with a run-time trip count, which would be partially unrolled. For Hexagon, if we partially unroll a loop, we'd also like to use our hardware loop instructions. That is, unrolling and hardware loops are

On Mon, Jan 30, 2017 at 3:51 PM Mehdi Amini via llvm-dev < llvm-dev at lists.llvm.org> wrote: > On Jan 30, 2017, at 10:49 AM, Dehao Chen via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > > Currently, loop fully unroller shares the same default threshold as loop > dynamic unroller and partial unroller. This seems conservative because > unlike dynamic/partial

> On Jan 30, 2017, at 4:56 PM, Dehao Chen <dehao at google.com> wrote: > > > > On Mon, Jan 30, 2017 at 3:56 PM, Chandler Carruth <chandlerc at google.com <mailto:chandlerc at google.com>> wrote: > On Mon, Jan 30, 2017 at 3:51 PM Mehdi Amini via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: >> On Jan 30,

The loop rotation pass does modify the function, which I'm guessing means that a FunctionPassManager can be used to run LoopPasses (this is not obvious to me after looking through the FunctionPassManager code). Unfortunately none of the other passes I'm using (ScalarEvolution, LCSSA, IndVarSimplify, and LoopUnroll) appear to have an effect. I verified that the function can be loop

Hi, We've a target which has hardware support for zero-overhead loops. Currently, we cannot detect them because the loop unroller is unrolling them before entering into the codegen. Looking at its implementation, it seems that it checks if it is profitable to unroll it or not based on certain parameters. Given that zero cost loops building is based more or less on the same constraints

On 11/21/2012 10:31 AM, Ivan Llopard wrote: > > Does Hexagon provides the same loop support? How have you addressed this? Yes, Hexagon has hardware support for loops: you set up the loop start address, number of iterations and indicate where the loop ends, and the hardware would execute the code repeatedly until the count goes down to zero. I'm not aware of any specific changes that

On Mon, Jan 30, 2017 at 3:56 PM, Chandler Carruth <chandlerc at google.com> wrote: > On Mon, Jan 30, 2017 at 3:51 PM Mehdi Amini via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> On Jan 30, 2017, at 10:49 AM, Dehao Chen via llvm-dev < >> llvm-dev at lists.llvm.org> wrote: >> >> Currently, loop fully unroller shares the same default

In r200270 I added support to unroll conditional stores in the loop vectorizer. It is currently off pending further benchmarking and can be enabled with "-mllvm -vectorize-num-stores-pred=1”. Furthermore, I added a heuristic to unroll until load/store ports are saturated “-mllvm enable-loadstore-runtime-unroll” instead of the pure size based heuristic. Those two together with a patch that

On Mon, Jan 30, 2017 at 4:59 PM Mehdi Amini <mehdi.amini at apple.com> wrote: > > > Another question is about PGO integration: is it already hooked there? > Should we have a more aggressive threshold in a hot function? (Assuming > we’re willing to spend some binary size there but not on the cold path). > > > I would even wire the *unrolling* the other way: just

Currently, loop fully unroller shares the same default threshold as loop dynamic unroller and partial unroller. This seems conservative because unlike dynamic/partial unrolling, fully unrolling will not affect LSD/ICache performance. In https://reviews.llvm.org/D28368, I proposed to double the threshold for loop fully unroller. This will change the codegen of several SPECCPU benchmarks: Code

Recollected the data from trunk head with stddev data and more threshold data points attached: Performance: stddev/mean 300 450 600 750 403 0.37% 0.11% 0.11% 0.09% 0.79% 433 0.14% 0.51% 0.25% -0.63% -0.29% 445 0.08% 0.48% 0.89% 0.12% 0.83% 447 0.16% 3.50% 2.69% 3.66% 3.59% 453 0.11% 1.49% 0.45% -0.07% 0.78% 464 0.17% 0.75% 1.80% 1.86% 1.54% Code size: 300 450 600 750 403 0.56% 2.41% 2.74% 3.75%

On 11/08/2011 03:36 PM, Hal Finkel wrote: > On Tue, 2011-11-08 at 12:12 +0100, Tobias Grosser wrote: >> On 11/08/2011 11:45 AM, Hal Finkel wrote: >>> I've attached the latest version of my autovectorization patch. >>> >>> Working through the test suite has proved to be a productive >>> experience ;) -- And almost all of the bugs that it revealed

Hi Brendon, Krzysztof, Thanks for your responses. On 21/11/2012 20:49, Brendon Cahoon wrote: > I just wanted to add to Krzysztof's response. I'm not sure if you're > referring to the case when a compile-time trip count loop is completely > unrolled or for a loop with a run-time trip count, which would be partially > unrolled. For Hexagon, if we partially unroll a loop,

There's been some recent noise on the mailing list about requiring -fno-rtti; http://lists.llvm.org/pipermail/llvm-dev/2015-August/089010.html Could that be it? On Sat, Aug 22, 2015 at 12:21 AM, Xiangyang Guo via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi, James and Philip, Thanks for your help. > > Based on your advice, I downloaded llvm-3.7. However, with this new

Hi, I want to use loop unrolling pass, however, I find that loop unrolling will introduces conditional branch at end of every "unrolled" part. For example, consider the following code *void foo( int n, int array_x[])* *{* * for (int i=0; i < n; i++)* * array_x[i] = i; * *}* Then I use this command "opt-3.5 try.bc -mem2reg -loops -loop-simplify -loop-rotate -lcssa