The loop count (n) directive indicates the loop count is likely to be n. The syntax for this directive is:
#pragma loop count (n)
where n is an integer constant. The value of loop count affects heuristics used in software pipelining, vectorization and loop-transformations.
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#pragma loop count (10000)
for(i=0; i<m; i++) { //swp likely to occur in this loop a[i]=b[i]+1.2; } |
The distribute point directive indicates to the compiler a preference of performing loop distribution. The syntax for this directive is:
#pragma distribute point
Loop distribution may cause large loops be distributed into smaller ones. This may enable software pipelining for more loops. If the directive is placed inside a loop, the distribution is performed after the directive and any loop-carried dependency is ignored. If the directive is placed before a loop, the compiler will determine where to distribute and data dependency is observed. Only one distribute directive is supported when placed inside the loop.
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#pragma distribute point
for(i=1; i<m; i++) { b[i]=a[i]+1;
...
//Compiler will automatically //decide where to distribute. //Data dependency is observed.
c[i]=a[i]+b[i];
...
d[i]=c[i]+1; }
for(i=1; i<m; i++) { b[i]=a[i]+1;
...
#pragma distribute point
//Distribution will start here, //ignoring all loop-carried dependency.
sub(a,n); c[i]=a[i]+b[i];
...
d[i]=c[i]+1; } |