Where is restrict keyword used in dependence analysis?

[Bingfeng Mei]

Hello,

I am porting to GCC 4.3.0 for our VLIW processor, and try to utilize
improved restrict keyword support. Somehow, I find for normal data
types, including vector types up to 8bytes, the restrict keyword works
just fine. But for wider vector, such as 4 32-bit word type, the
restrict keyword doesn't work any more. For example, for the first two
following functions, compiler can unroll (-funroll-all-loops) loops and
produces good schedule, where load instructions of next iteration can be
moved beyond store instruction of this iteration.  But for the third
example, it is different. As suggested in .sched2 file, the compiler can
only resolve dependence of next load instructions after store
instruction of this iteration is scheduled. I tried to print out
tree-ssa files by using -fdump-tree-all. Unliked previous GCC (4.2.1),
the information in those files is not helpful at all.  I don't know
where to look at now. Could someone point me some files/functions/data
structures by which restrict keyword is used and passed to dependence
anaylsis part?  Thanks in advance.

Bingfeng Mei
Broadcom UK

Example code: 

typedef int    V4W  __attribute__ ((vector_size (16)));
typedef int    V2W  __attribute__ ((vector_size (8))); 

void tst(int * restrict a, int * restrict b, int * restrict c)
{
  int i;
  for(i = 0; i < 256; i++){
    c[i] = a[i] + b[i];
  }
}  
 
void tst2(int * restrict a, int * restrict b, int * restrict c)
{
  int i;
  for(i = 0; i < 256; i++){
    c[i] = a[i] + b[i];
  }
}  
 
void tst3(V4W * restrict a, V4W * restrict b, V4W * restrict c)
{
  int i;
  for(i = 0; i < 256; i++){
    c[i] = a[i] + b[i];
  }
}