[all-commits] [llvm/llvm-project] 6e78a3: [OPENMP50]Codegen for scan directive in for simd r...

[Alexey Bataev via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 6e78a3086a7f563cc55d2ba83a8697b3320857fb
      https://github.com/llvm/llvm-project/commit/6e78a3086a7f563cc55d2ba83a8697b3320857fb
  Author: Alexey Bataev <a.bataev at hotmail.com>
  Date:   2020-06-16 (Tue, 16 Jun 2020)

  Changed paths:
    M clang/lib/CodeGen/CGStmtOpenMP.cpp
    A clang/test/OpenMP/for_simd_scan_codegen.cpp

  Log Message:
  -----------
  [OPENMP50]Codegen for scan directive in for simd regions.

Summary:
Added codegen for scan directives in parallel for regions.

Emits the code for the directive with inscan reductions.
Original code:
```
 #pragma omp for simd reduction(inscan, op : ...)
for(...) {
  <input phase>;
  #pragma omp scan (in)exclusive(...)
  <scan phase>
}
```
is transformed to something:
```
size num_iters = <num_iters>;
<type> buffer[num_iters];
 #pragma omp for simd
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 simd
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/D81658