It is said that gcc implements loop unswitching on SSA and RTL representations. At the same time, in this link http://gcc.gnu.org/projects/tree-ssa/vectorization.html it is said that loop unswitching is not done to overcome branch statements to vectorize loops. When I run a simple code which has a loop with 'if' statement gcc-4.1.2 is unable to vectorize loop. The prg is at bottom. It was compiled as 'gcc -march=pentium4 -O3 -S -ftree-vectorize' -funswitch-loops 6.c Can anyone resolve this ambiguity? -------------------------------------------------------- 1 #include<stdio.h> 2 3 int main() 4 { 5 6 int c[100],a[100],b[100]; 7 int i,j,n=80; 8 for(i=0;i<n;i++) 9 a[i]=b[i]=c[i]=i; 10 11 for (i=0;i<n;i++) 12 { 13 a[i] = b[i]-1; 14 if(c[i]) 15 c[i]=b[i]*2; 16 //b[i+10] = a[i]+5; 17 } 18 19 for (i=0;i<n;i++) 20 printf("\n %d %d %d\n",b[i],c[i],a[i]); 21 } ___________________________________________________________ Yahoo! Answers - Got a question? Someone out there knows the answer. Try it now. http://uk.answers.yahoo.com/
