1ec469cf4c
[OPENMP50]Codegen for scan directives in parallel for regions.
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Summary:
Added codegen for scan directives in parallel for regions.
Emits the code for the directive with inscan reductions.
Original code:
```
#pragma omp parallel for reduction(inscan, op : ...)
for() {
<input phase>;
#pragma omp scan (in)exclusive(...)
<scan phase>
}
```
is transformed to something:
```
#pragma omp parallel
{
size num_iters = <num_iters>;
<type> buffer[num_iters];
#pragma omp for
for (i: 0..<num_iters>) {
<input phase>;
buffer[i] = red;
}
#pragma omp barrier
for (int k = 0; k != ceil(log2(num_iters)); ++k)
for (size cnt = last_iter; cnt >= pow(2, k); --k)
buffer[i] op= buffer[i-pow(2,k)];
#pragma omp for
for (0..<num_iters>) {
red = InclusiveScan ? buffer[i] : buffer[i-1];
<scan phase>;
}
}
```
Reviewers: jdoerfert
Subscribers: yaxunl, guansong, sstefan1, cfe-commits, caomhin
Tags: #clang
Differential Revision: https://reviews.llvm.org/D81478
2020-06-18 11:56:55 -04:00
Saiyedul Islam