https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100059
Bug ID: 100059
Summary: [OpenMP] wrong code with 'declare target link' and a
scalar variable
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Keywords: openmp, wrong-code
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
CC: jakub at gcc dot gnu.org
Target Milestone: ---
Target: nvptx-none
Created attachment 50578
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50578&action=edit
Testcase, compile with 'gcc -fopenmp' with an (nvptx) offloading enabled
compiler
The attached testcase has four global vars:
int a[N], b[N], c[N];
int i = 0;
which are used with:
#pragma omp declare target link(a,c,b,i)
and
#pragma omp target map(to: i) map(tofrom: a, b, c)
update();
After the call, the one array is not updated but has the previous host value:
* For 'declare target link(a,c,b,i)': not updated array is 'b'
* For 'declare target link(a,b,c,i)': not updated array is 'c'
Namely, the testcase shows:
i=5: A=5, B=6, C=7 // Original host value
i=5: A=6, B=6, C=10 // target call to 'update': 'B' is not updated
i=5: A=7, B=8, C=13 // host update, OK
Additionally, when using 'for (int i' in 'update': The error only shows up if
there is 'i'
And it occurs for the item before 'i', namely:
link(a,c,b,i) → 'b' is wrong
link(a,c,i,b) → 'c' is wrong
The issue occurs with nvptx. It works without offloading and I think it works
with GCN (did not show up in the test logs, but I have not manually verified).
