cc374d8056
Summary: Currently, OpenMP handles the `omp requires` clause by emitting a global constructor into the runtime for every translation unit that requires it. However, this is not a great solution because it prevents us from having a defined order in which the runtime is accessed and used. This patch changes the approach to no longer use global constructors, but to instead group the flag with the other offloading entires that we already handle. This has the effect of still registering each flag per requires TU, but now we have a single constructor that handles everything. This function removes support for the old `__tgt_register_requires` and replaces it with a warning message. We just had a recent release, and the OpenMP policy for the past four releases since we switched to LLVM is that we do not provide strict backwards compatibility between major LLVM releases now that the library is versioned. This means that a user will need to recompile if they have an old binary that relied on `register_requires` having the old behavior. It is important that we actively deprecate this, as otherwise it would not solve the problem of having no defined init and shutdown order for `libomptarget`. The problem of `libomptarget` not having a define init and shutdown order cascades into a lot of other issues so I have a strong incentive to be rid of it. It is worth noting that the current `__tgt_offload_entry` only has space for a 32-bit integer here. I am planning to overhaul these at some point as well.
85 lines
2.5 KiB
C
85 lines
2.5 KiB
C
// clang-format off
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// RUN: %libomptarget-compile-generic -DREQ=1 && %libomptarget-run-generic 2>&1 | %fcheck-generic -check-prefix=GOOD
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// RUN: %libomptarget-compile-generic -DREQ=2 && not %libomptarget-run-generic 2>&1 | %fcheck-generic -check-prefix=BAD
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// clang-format on
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/*
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Test for the 'requires' clause check.
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When a target region is used, the requires flags are set in the
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runtime for the entire compilation unit. If the flags are set again,
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(for whatever reason) the set must be consistent with previously
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set values.
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*/
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#include <omp.h>
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#include <stdio.h>
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// ---------------------------------------------------------------------------
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// Various definitions copied from OpenMP RTL
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typedef struct {
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void *addr;
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char *name;
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size_t size;
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int32_t flags;
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int32_t data;
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} __tgt_offload_entry;
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enum Flags {
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OMP_REGISTER_REQUIRES = 0x10,
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};
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typedef struct {
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void *ImageStart;
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void *ImageEnd;
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__tgt_offload_entry *EntriesBegin;
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__tgt_offload_entry *EntriesEnd;
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} __tgt_device_image;
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typedef struct {
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int32_t NumDeviceImages;
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__tgt_device_image *DeviceImages;
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__tgt_offload_entry *HostEntriesBegin;
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__tgt_offload_entry *HostEntriesEnd;
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} __tgt_bin_desc;
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void __tgt_register_lib(__tgt_bin_desc *Desc);
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void __tgt_unregister_lib(__tgt_bin_desc *Desc);
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// End of definitions copied from OpenMP RTL.
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// ---------------------------------------------------------------------------
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void run_reg_requires() {
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// Before the target region is registered, the requires registers the status
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// of the requires clauses. Since there are no requires clauses in this file
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// the flags state can only be OMP_REQ_NONE i.e. 1.
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// This is the 2nd time this function is called so it should print SUCCESS if
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// REQ is compatible with `1` and otherwise cause an error.
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__tgt_offload_entry entries[] = {{NULL, "", 0, OMP_REGISTER_REQUIRES, 1},
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{NULL, "", 0, OMP_REGISTER_REQUIRES, REQ}};
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__tgt_device_image image = {NULL, NULL, &entries[0], &entries[1] + 1};
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__tgt_bin_desc bin = {1, &image, &entries[0], &entries[1] + 1};
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__tgt_register_lib(&bin);
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printf("SUCCESS");
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__tgt_unregister_lib(&bin);
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// clang-format off
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// GOOD: SUCCESS
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// BAD: omptarget fatal error 2: '#pragma omp requires reverse_offload' not used consistently!
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// clang-format on
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}
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// ---------------------------------------------------------------------------
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int main() {
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run_reg_requires();
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// This also runs reg requires for the first time.
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#pragma omp target
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{}
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return 0;
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}
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