llvm-project/offload/test/offloading/target_update_strided_struct_partial_to.c
Amit Tiwari 230b437d05
[Clang][OpenMP] Handle check for non-contiguous mapping in pointer-based array sections (#157443)
### 1. ElementType deduction for pointer-based array sections

Problem: Pointer-based array sections were previously ignored during
`ElementType` deduction, leading to incorrect assumptions about array
item types.

This often resulted in out-of-bounds access, as seen in the assertion
failure:
```
Assertion `idx < size()' failed.
llvm-project/llvm/include/llvm/ADT/SmallVector.h:292:
reference llvm::SmallVectorTemplateCommon<llvm::Value *>::operatorsize_type
[T = llvm::Value *]

```
Fix: Added a check in clang/lib/CodeGen/CGOpenMPRuntime.cpp to ensure
`ElementType` is correctly detected for cases involving non-contiguous
updates with a base pointer.
Impact: Resolves failures in OpenMP_VV (formerly sollve_vv) and other
offload/clang-OpenMP tests:

All tests under:

https://github.com/OpenMP-Validation-and-Verification/OpenMP_VV/tree/master/tests/5.0/target_update

test_target_update_mapper_from_discontiguous.c
test_target_update_mapper_to_discontiguous.c
test_target_update_to_discontiguous.c
test_target_update_from_discontiguous.c



### 2. Zero-dimension propagation in struct member mappings

Problem: A zero-dimension entry for struct members introduced
inconsistencies in complex mapping logic within OMPIRBuilder.cpp.

Placeholder zeros propagated to emitNonContiguousDescriptor(), breaking
reverse indexing logic and corrupting IR:

Loops assume `Dims[I] >= 1`. When `Dims[I] == 0`:

Reverse indexing still stores pointers to uninitialized allocas or
mismatched slots. Runtime interprets `ArgSizes[I]` (derived from
`Dims[I])` as dimensionality, causing size/offset calculations to
collapse to zero → results in `size=0` async copy and plugin interface
errors.

Fix: Prepend a synthetic dimension of size 1 instead of appending a
zero, preserving correctness in `targetDataUpdate()` for non-contiguous
updates.
Impact: Added dedicated test cases that previously failed on main.
2025-12-23 12:57:12 +05:30

86 lines
1.9 KiB
C

// RUN: %libomptarget-compile-run-and-check-generic
// This test checks that #pragma omp target update to(s.data[0:2:3]) correctly
// updates every third element (stride 3) from the host to the device
// for struct member arrays.
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#define LEN 11
typedef struct {
double data[LEN];
int len;
} T;
int main() {
T s;
s.len = LEN;
// Initialize struct array on host with simple sequential values
for (int i = 0; i < LEN; i++)
s.data[i] = i;
printf("original host struct array values:\n");
for (int i = 0; i < LEN; i++)
printf("%.1f\n", s.data[i]);
printf("\n");
#pragma omp target data map(tofrom : s)
{
// Initialize all elements on device to 20
#pragma omp target map(tofrom : s)
{
for (int i = 0; i < s.len; i++)
s.data[i] = 20.0;
}
// Modify host struct data for elements that will be updated (set to 10)
s.data[0] = 10.0;
s.data[3] = 10.0;
// indices 0,3 only
#pragma omp target update to(s.data[0 : 2 : 3])
// Verify on device by adding 5 to all elements
#pragma omp target map(tofrom : s)
{
for (int i = 0; i < s.len; i++)
s.data[i] += 5.0;
}
}
printf("device struct array values after update to:\n");
for (int i = 0; i < LEN; i++)
printf("%.1f\n", s.data[i]);
// CHECK: original host struct array values:
// CHECK-NEXT: 0.0
// CHECK-NEXT: 1.0
// CHECK-NEXT: 2.0
// CHECK-NEXT: 3.0
// CHECK-NEXT: 4.0
// CHECK-NEXT: 5.0
// CHECK-NEXT: 6.0
// CHECK-NEXT: 7.0
// CHECK-NEXT: 8.0
// CHECK-NEXT: 9.0
// CHECK-NEXT: 10.0
// CHECK: device struct array values after update to:
// CHECK-NEXT: 15.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 15.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 25.0
// CHECK-NEXT: 25.0
return 0;
}