[LLVMdev] Auto-vectorization in GCC 4.0

[Devang Patel]

llvmgcc4 emits LLVM byte code before executing GCC optimizations, so  
one can say that llvmgcc4 disables all GCC optimizations.

On Jul 31, 2006, at 11:01 AM, Zhiru Zhang wrote:

> Hi,
> I am trying to turn on the new GCC auto-vectorization feature  
> within llvmgcc4. Below is the command I used, but nothing was  
> vectorized. Does it mean that llvmgcc4 has disabled this  
> optimization and all I can do is to embed SSE intrinsics in the  
> source code by hand?
>
> Thanks!
>
> ./llvm-gcc4-x86/bin/llvm-gcc -c -O2 -ftree-vectorize -msse -ftree- 
> vectorizer-verbose=5 -emit-llvm vec.c -o vec.bc
>
> ////////////////////vec.c/////////////////////////
> int a[256], b[256], c[256];
> foo () {
>   int i;
>   for (i=0; i<256; i++){
>     a[i] = b[i] + c[i];
>   }
> }
>
>
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-
Devang



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