Files
llvm/offload/test/offloading/strided_update.c
Amit Tiwari 2074e1320f [Clang][OpenMP] Non-contiguous strided update (#144635)
This patch handles the strided update in the `#pragma omp target update
from(data[a:b:c])` directive where 'c' represents the strided access
leading to non-contiguous update in the `data` array when the offloaded
execution returns the control back to host from device using the `from`
clause.

Issue: Clang CodeGen where info is generated for the particular
`MapType` (to, from, etc), it was failing to detect the strided access.
Because of this, the `MapType` bits were incorrect when passed to
runtime. This led to incorrect execution (contiguous) in the
libomptarget runtime code.

Added a minimal testcase that verifies the working of the patch.
2025-08-12 19:32:15 +05:30

55 lines
1.3 KiB
C

// This test checks that "update from" clause in OpenMP is supported when the
// elements are updated in a non-contiguous manner. This test checks that
// #pragma omp target update from(data[0:4:2]) correctly updates only every
// other element (stride 2) from the device to the host
// RUN: %libomptarget-compile-run-and-check-generic
#include <omp.h>
#include <stdio.h>
int main() {
int len = 8;
double data[len];
#pragma omp target map(tofrom : len, data[0 : len])
{
for (int i = 0; i < len; i++) {
data[i] = i;
}
}
// Initial values
printf("original host array values:\n");
for (int i = 0; i < len; i++)
printf("%f\n", data[i]);
printf("\n");
#pragma omp target data map(to : len, data[0 : len])
{
// Modify arrays on device
#pragma omp target
for (int i = 0; i < len; i++) {
data[i] += i;
}
#pragma omp target update from(data[0 : 4 : 2])
}
// CHECK: 0.000000
// CHECK: 1.000000
// CHECK: 4.000000
// CHECK: 3.000000
// CHECK: 8.000000
// CHECK: 5.000000
// CHECK: 12.000000
// CHECK: 7.000000
// CHECK-NOT: 2.000000
// CHECK-NOT: 6.000000
// CHECK-NOT: 10.000000
// CHECK-NOT: 14.000000
printf("from target array results:\n");
for (int i = 0; i < len; i++)
printf("%f\n", data[i]);
printf("\n");
return 0;
}