[llvm-dev] Auto-vectorization option

[Nigel Perks via llvm-dev]

Try   opt -S   to get text IR instead of bitcode.

The second group of commands use   clang -c   so produce a compiled object file. For text IR you need   -S -emit-llvm   like in the first group.

Nigel


From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of Sudakshina Dutta via llvm-dev
Sent: 14 May 2021 04:17
To: LLVM Development List <llvm-dev at lists.llvm.org>
Subject: [llvm-dev] Auto-vectorization option

Dear all,

Greetings. I want to generate the intermediate code (.ll file) after having LLVM auto-vectorization transformation on the source C file. I have the following code  (find_max.c) on which I want to apply auto-vectorization.

int main()
{
    int i, n, max, arr[50];
    for(i = 0; i < 35; i++)
    {
        printf("arr[%d] = ", i);
        scanf("%d", &arr[i]);
    }
    max = arr[0];
    for(i = 1; i < 35; i++)
    {
        if(arr[i] > max)
        {
            max = arr[i];
        }
    }

}

I have tried the following.


  1.  clang  -S -emit-llvm find_max.c -o find_max.ll
  2.  opt -loop-vectorize -force-vector-width=8 find_max.ll -o find_max_opt.ll
and

  1.  clang -O3 -c find_max.c -Rpass=vector -Rpass-analysis=vector
  2.  clang -O3 -c find_max.c -Rpass=vector -Rpass-analysis=vector -o find_max.ll

All the above options generate binary files. I request you to please help.

Thanks and regards,
Sudakshina
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