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91f5f974cb
Summary: This patch adds an RPC interface that lives directly in the OpenMP device runtime. This allows OpenMP to implement custom opcodes. Currently this is only providing the host call interface, which is the raw version of reverse offloading. Previously this lived in `libc/` as an extension which is not the correct place. The interface here uses a weak symbol for the RPC client by the same name that the `libc` interface uses. This means that it will defer to the libc one if both are present so we don't need to set up multiple instances. The presense of this symbol is what controls whether or not we set up the RPC server. Because this is an external symbol it normally won't be optimized out, so there's a special pass in OpenMPOpt that deletes this symbol if it is unused during linking. That means at `O0` the RPC server will always be present now, but will be removed trivially if it's not used at O1 and higher.
63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
// RUN: %libomptarget-compile-run-and-check-generic
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#include <assert.h>
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#include <omp.h>
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#include <stdio.h>
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#pragma omp begin declare variant match(device = {kind(gpu)})
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// Extension provided by the 'libc' project.
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unsigned long long __llvm_omp_host_call(void *fn, void *args, size_t size);
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#pragma omp declare target to(__llvm_omp_host_call) device_type(nohost)
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#pragma omp end declare variant
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#pragma omp begin declare variant match(device = {kind(cpu)})
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// Dummy host implementation to make this work for all targets.
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unsigned long long __llvm_omp_host_call(void *fn, void *args, size_t size) {
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return ((unsigned long long (*)(void *))fn)(args);
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}
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#pragma omp end declare variant
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typedef struct args_s {
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int thread_id;
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int block_id;
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} args_t;
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// CHECK-DAG: Thread: 0, Block: 0
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// CHECK-DAG: Thread: 1, Block: 0
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// CHECK-DAG: Thread: 0, Block: 1
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// CHECK-DAG: Thread: 1, Block: 1
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// CHECK-DAG: Thread: 0, Block: 2
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// CHECK-DAG: Thread: 1, Block: 2
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// CHECK-DAG: Thread: 0, Block: 3
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// CHECK-DAG: Thread: 1, Block: 3
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unsigned long long foo(void *data) {
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assert(omp_is_initial_device() && "Not executing on host?");
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args_t *args = (args_t *)data;
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printf("Thread: %d, Block: %d\n", args->thread_id, args->block_id);
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return 42;
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}
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void *fn_ptr = NULL;
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#pragma omp declare target to(fn_ptr)
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int main() {
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fn_ptr = (void *)&foo;
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#pragma omp target update to(fn_ptr)
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int failed = 0;
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#pragma omp target teams num_teams(4) map(tofrom : failed)
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#pragma omp parallel num_threads(2)
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{
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args_t args = {omp_get_thread_num(), omp_get_team_num()};
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unsigned long long res =
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__llvm_omp_host_call(fn_ptr, &args, sizeof(args_t));
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if (res != 42)
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#pragma omp atomic write
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failed = 1;
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}
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// CHECK: PASS
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if (!failed)
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printf("PASS\n");
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}
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