similar to: Loop Unroll

This is my example (for.c): #include <stdio.h> int add(int a, int b) { return a + b; } int main() { int a, b, c, d; a = 5; b = 15; c = add(a, b); d = 0; for(int i=0;i<16;i++) d = add(c, d); } I run: $ clang -O0 -Xclang -disable-O0-optnone -emit-llvm for.c -S -o forO0.ll $ opt -O0 -S --loop-unroll --unroll-count=4 -view-cfg forO0.ll -o for-opt00-unroll4.ll

Awesome, thanks! Now I have another question. I have a matrix multiplication code. This is my code: #include <stdio.h> #include <stdlib.h> #define n 4 int main(int argc, char *argv[]) { int i, j, k; int A[n][n], B[n][n], C[n][n]; for(i=0;i<n;i++){ for(j=0;j<n;j++){ A[i][j] = 1; B[i][j] = 2; C[i][j] = 0; } }

Hi, I just tried llvm-3.8 (LLVM SVN Repository). With this version, -fno-rtti can help me to compile my code and -irce can help me to do a better job for loop unrolling. However, I still have one question. If I use Clang to compile a piece of c++ code to .bc and then use 'opt -loop-rotate -loop-unroll -irce', I can get what I want. I mean, there is no conditional branch at the end of each

Hi, Mehdi, For example, I have this very simple source code: void foo( int n, int array_x[]) { for (int i=0; i < n; i++) array_x[i] = i; } After I use "clang -emit-llvm -o bc_from_clang.bc -c try.cc", I get bc_from_clang.bc. With my code (using LLVM IRbuilder API), I get bc_from_api.bc. Attachment please find thse two files. I also past the IR here.

Thanks for your point that out. I just add DataLayout in my code such as "mod->setDataLayout("e-m:e-i64:64-f80:128-n8:16:32:64-S128");", still no luck. I'm really confused about this. Do I need to add more passes before -loop-unroll? On Sat, Aug 22, 2015 at 11:36 AM, Mehdi Amini <mehdi.amini at apple.com> wrote: > > On Aug 22, 2015, at 7:27 AM, Xiangyang

First off, I just want to say wow and thank you. This kind of data is amazing. =D On Thu, Feb 16, 2017 at 2:46 AM Kristof Beyls <Kristof.Beyls at arm.com> wrote: > The biggest relative code size increases indeed didn't happen for the > biggest programs, but instead for a few programs weighing in at about 100KB. > I'm assuming the Google benchmark set covers much bigger

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

Hi Xiangyang, The algorithm for loop unrolling was changed post-3.5 to do more what you'd expect. If you use 3.6 or 3.7 you'll likely get better results. Cheers, James On Thu, 20 Aug 2015 at 18:09 Philip Reames via llvm-dev < llvm-dev at lists.llvm.org> wrote: > On 08/20/2015 07:38 AM, Xiangyang Guo via llvm-dev wrote: > > Hi, > > I want to use loop unrolling

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, You might want to try running -loops -loop-simplify before loop unroll. >From loop simplify.cpp This pass performs several transformations to transform natural loops into a00011 // simpler form, which makes subsequent analyses and transformations simpler and00012 // more effective. Arushi On Tue, May 3, 2011 at 2:17 PM, Manish Gupta <mgupta.iitr at gmail.com> wrote: > You

Even after all the sequence of commands below bit-code is not showing any effect of loop-unrolling *manish at manish:~/Test2$ llvm-gcc-4.2 -O2 -emit-llvm Hello.c -c -o Hello.bc* *manish at manish:~/Test2$ opt-2.8 -loops Hello.bc -o Hello1.bc* *manish at manish:~/Test2$ opt-2.8 -loopsimplify Hello1.bc -o Hello2.bc* *manish at manish:~/Test2$ opt-2.8 -indvars Hello2.bc -o Hello3.bc* *manish at

On Wed, Jan 15, 2014 at 5:30 PM, Nadav Rotem <nrotem at apple.com> wrote: > Was the vectorizer successful in unrolling the loop in quantum_sigma_x? I > wonder if 'size’ is typically high or low. No. The vectorizer stated that it wasn't going to bother with the loop because it wasn't profitable. Specifically: LV: Checking a loop in "quantum_sigma_x" LV: Found a

On Mon, Feb 27, 2012 at 9:30 AM, Benjamin Kramer <benny.kra at googlemail.com> wrote: > > On 27.02.2012, at 17:13, Николай Лихогруд wrote: > >> Dear LLVM, >> >>     Consider two loops with one interation - >>     First with constant lower bound, second with usual non-constant lower bound: >> >>     int main(int argc, char ** argv) >>     {

1. You should run the passes in the same opt command, for passes like loops which is an analysis pass provides results to the following passes. 2. You can pass a -debug flag to opt to see the some debugging info. 3. I tried this opt -mem2reg -loops -loopsimplify -loop-unroll -unroll-count=3 -debug loop.o -o tt.bc and got this message. Loop Size = 14 Can't unroll; loop not terminated by

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

On 27.02.2012, at 18:49, Eli Friedman wrote: > On Mon, Feb 27, 2012 at 9:30 AM, Benjamin Kramer > <benny.kra at googlemail.com> wrote: >> >> On 27.02.2012, at 17:13, Николай Лихогруд wrote: >> >>> Dear LLVM, >>> >>> Consider two loops with one interation - >>> First with constant lower bound, second with usual

Hello, I've come across another example: I'm compiling with clang -S -emit-llvm -std=gnu99 -O3 clang version 2.9 (trunk 118238) Target: x86_64-unknown-linux-gnu Thread model: posix I take the code: int loops(int x) { int ret = 0; for(int i = 0; i < x; i++) { for(int j = 0; j < x; j++) { ret += 1; } } return ret; } and the

Hi All, I am trying to unroll the below loop, but couldn't as SCEV returns TripCount as 0. void foo(int x) { int p, i = 1; int mat[6][6][6]; for (p = x+3 ; p<= x+6 ;p++) mat[x][p][i] = mat[x][p][i] + 5; } For a quick reference I have added the generated IR compiled with clang using -O3. Please let me know if this is an known issue in SCEV or I am missing something here ? ;

> On Feb 16, 2017, at 4:41 PM, Xinliang David Li via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > > > On Thu, Feb 16, 2017 at 3:45 PM, Chandler Carruth via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: > First off, I just want to say wow and thank you. This kind of data is amazing. =D > > On Thu, Feb 16, 2017 at

I have modified the example test case for UB error, still it didn’t unroll void foo(int x) { int p, i = 1; int mat[9][9][9]; for (p = (x+1) ; p < (x+3) ;p++) mat[x][p-1][i] = mat[x][p-1][i] + 5; } Regard, Deepali From: Kevin Choi [mailto:code.kchoi at gmail.com] Sent: Friday, September 16, 2016 1:20 PM To: Rai, Deepali Cc: llvm-dev at lists.llvm.org Subject: Re: [llvm-dev] SCEV