similar to: unable to emit vectorized code in LLVM IR

I want to vectorize the user given inputs. when opt does vectorization user supplied inputs (from a text file) will be added using AVX vector instructions. as you pointed; When i changed my code to following: int main(int argc, char** argv) { int a[1000], b[1000], c[1000]; int aa=atoi(argv[1]), bb=atoi(argv[2]); for (int i=0; i<1000; i++) { a[i]=aa, b[i]=bb; c[i]=a[i] + b[i];

i removed printf from loop. Now getting no error. but the IR doesnot contain vectorized code. IR Output is as follows: ; ModuleID = 'sum-vec.ll' source_filename = "sum-vec.c" target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" ; Function Attrs: norecurse nounwind readnone uwtable define i32 @main(i32, i8**

even if i make my code as follows: vectorized instructions not get emitted. What to do? int main(int argc, char** argv) { int a[1000], b[1000], c[1000]; int g=0; int aa=atoi(argv[1]), bb=atoi(argv[2]); for (int i=0; i<1000; i++) { a[i]=aa, b[i]=bb; c[i]=a[i] + b[i]; g+=c[i]; } printf("sum: %d\n", g); return 0; } On Thu, Aug 17, 2017 at 10:03 PM, Craig Topper <craig.topper at

I assume compiler knows that your only have 2 input values that you just added together 1000 times. Despite the fact that you stored to a[i] and b[i] here, nothing reads them other than the addition in the same loop iteration. So the compiler easily removed the a and b arrays. Same with 'c', it's not read outside the loop so it doesn't need to exist. So the compiler turned your

Ok. I have managed to vectorize the second loop in the following code. But the first loop is still not vectorized? Why? int main(int argc, char** argv) { int a[1000], b[1000], c[1000]; int g=0; int aa=atoi(argv[1]), bb=atoi(argv[2]); for (int i=0; i<1000; i++) { a[i]=aa+i, b[i]=bb+i;} for (int i=0; i<1000; i++) { c[i]=a[i] + b[i]; g+=c[i]; } printf("sum: %d\n", g); return 0;

lli sum-vec03.ll 5 2 #0 0x0000000000c1f818 (lli+0xc1f818) #1 0x0000000000c1d90e (lli+0xc1d90e) #2 0x0000000000c1da5c (lli+0xc1da5c) #3 0x00007f987c2c3d10 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x10d10) #4 0x00007f987c6f0038 #5 0x0000000000989f8c (lli+0x989f8c) #6 0x00000000009383dc (lli+0x9383dc) #7 0x000000000057eedd (lli+0x57eedd) #8 0x00007f987b464a40 __libc_start_main

Does it happen due to loop carried dependence? if yes what is the solution to vectorize such codes? please reply. i m waiting. On Jul 1, 2017 12:30 PM, "hameeza ahmed" <hahmed2305 at gmail.com> wrote: > I even tried polly but still my llvm IR does not contain vector > instructions. i used the following command; > > clang -S -emit-llvm stencil.c -march=knl -O3

Hello, I am trying to vectorize following stencil code; #include <stdio.h> #define N 100351 // This function computes 2D-5 point Jacobi stencil void stencil(int a[restrict][N]) { int i, j, k; for (k = 0; k < 100; k++) { for (i = 1; i <= N-2; i++) { for (j = 1; j <= N-2; j++) { a[i][j] = 0.25 * (a[i][j] + a[i-1][j] + a[i+1][j] + a[i][j-1] +

I am able to vectorize it with the following code; #include <stdio.h> #define N 100351 // This function computes 2D-5 point Jacobi stencil void stencil(int a[][N], int b[][N]) { int i, j, k; for (k = 0; k < N; k++) { for (i = 1; i <= N-2; i++) for (j = 1; j <= N-2; j++) b[i][j] = 0.25 * (a[i][j] + a[i-1][j] + a[i+1][j] + a[i][j-1] + a[i][j+1]); for

<div> </div><div> </div><div>Hello,</div><div> </div><div>To me this is an issue in llvm loop vectorizer (if N is large enough to prevent complete unrolling of j-loop).</div><div> </div><div>Woud you mind to share stencil.ll than I would say more definitely what the issue

Hello, i am trying to vectorize a simple matrix multiplication in llvm; here is my code; #include <stdio.h> #define N 1000 // This function multiplies A[][] and B[][], and stores // the result in C[][] void multiply(int A[][N], int B[][N], int C[][N]) { int i, j, k; for (i = 0; i < N; i++) { for (j = 0; j < N; j++) { C[i][j] = 0;

Your problem is due to GVN partial reduction elimination (PRE) which introduces a PHI node the current loop vectorizer cannot handle: opt -O3 stencil.ll -pass-remarks=loop-vectorize -pass-remarks-missed=loop-vectorize -pass-remarks-analysis=loop-vectorize remark: <unknown>:0:0: loop not vectorized: value that could not be identified as reduction is used outside the loop remark:

Thank You. Right now to see the effect i did following changes; unsigned X86TTIImpl::getRegisterBitWidth(bool Vector) { if (Vector) { if (ST->hasAVX512()) return 65536; here i changed 512 to 65536. Then in loopvectorize.cpp i did following; assert(MaxVectorSize <= 2048 && "Did not expect to pack so many elements" " into

Hello, I need help here. I am able to adjust the vector width through WidestRegister value. When number of iterations=31 and I set vector width=32 it gives <16xi32> and <8xi32> instructions. However if i replicate same behavior with number of iterations=63 and I set vector width=64, no vector instructions are emitted. it should do as previous and gives <32xi32> and

Hello, I m unable to vectorize following kernel by opt tool; for (i = 0; i < _PB_NI; i++) for (j = 0; j < _PB_NJ; j++) { tmp[i][j] = 0; for (k = 0; k < _PB_NK; ++k) tmp[i][j] += alpha * A[i][k] * B[k][j]; } for (i = 0; i < _PB_NI; i++) for (j = 0; j < _PB_NL; j++) { D[i][j] *= beta; for (k = 0; k < _PB_NJ; ++k) D[i][j] +=

Thank You. I got it. Version issue. TTI.getRegisterBitWidth(true) How to put my target machine info in TTI? Please help. On Mon, Jul 23, 2018 at 11:33 PM, Friedman, Eli <efriedma at codeaurora.org> wrote: > On 7/23/2018 10:49 AM, hameeza ahmed via llvm-dev wrote: > > Thank You. > > But I cannot find your mentioned function

Hello, I m trying to set vector width using #pragma clang loop vectorize_width(32) but i m getting width 8 for the following kernel; #define M 128 #define N 128 #define SQRT_FUN(x) sqrtf(x) int main(int argc, char** argv) { /* Variable declaration/allocation. */ double float_n = (double)N; double data[N*M]; double corr[M*M]; double mean[M]; double stddev[M]; uint32_t

It would help if you sent the IR you're giving to opt or at least a complete C function and your clang command line. ~Craig On Wed, Mar 14, 2018 at 3:05 PM, hameeza ahmed <hahmed2305 at gmail.com> wrote: > Hello, > > I m unable to vectorize following kernel by opt tool; > > for (i = 0; i < _PB_NI; i++) > for (j = 0; j < _PB_NJ; j++) > { >

Hi Ahmed, >From what can be seen in the code snippet you provided, the reuse of XMM0 and XMM1 across loop-unroll instances does not inhibit instruction-level parallelism. Modern X86 processors use register renaming that can eliminate the dependencies in the instruction stream. In the example you provided, the processor should be able to identify the 2-vloads + vadd + vstore sequences as

Hi, Zvi, I agree. In the context of targeting the KNL, however, I'm a bit concerned about the addressing, and specifically, the size of the resulting encoding: > vmovdqu32 zmm0, zmmword ptr [rax + c+401280] ;load b[401280] in > zmm0 > > vpaddd zmm1, zmm1, zmmword ptr [rax + b+401344] > ; zmm1<-zmm1+b[401344] The KNL can only