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(#136729)
Summary:
Currently we build the OpenMP device runtime as part of the `offload/`
project. This is problematic because it has several restrictions when
compared to the normal offloading runtime. It can only be built with an
up-to-date clang and we need to set the target appropriately. Currently
we hack around this by creating the compiler invocation manually, but
this patch moves it into a separate runtimes build.
This follows the same build we use for libc, libc++, compiler-rt, and
flang-rt. This also moves it from `offload/` into `openmp/` because it
is still the `openmp/` runtime and I feel it is more appropriate. We do
want a generic `offload/` library at some point, but it would be trivial
to then add that as a separate library now that we have the
infrastructure that makes adding these new libraries trivial.
This most importantly will require that users update their build
configs, mostly adding the following lines at a minimum. I was debating
whether or not I should 'auto-upgrade' this, but I just went with a
warning.
```
-DLLVM_RUNTIME_TARGETS='default;amdgcn-amd-amdhsa;nvptx64-nvidia-cuda' \
-DRUNTIMES_nvptx64-nvidia-cuda_LLVM_ENABLE_RUNTIMES=openmp \
-DRUNTIMES_amdgcn-amd-amdhsa_LLVM_ENABLE_RUNTIMES=openmp \
```
This also changed where the `.bc` version of the library lives, but it's
still created.
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Avoid altering existing function signatures of the kmpc interface to fix
regressions in the runtime optimization (OpenMPOpt).
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OpenMP 6.0 12.1.2 specifies the behavior of the strict modifier for the
num_threads clause on parallel directives, along with the message and
severity clauses. This commit implements necessary device runtime
changes.
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Kernels which are marked as SPMD-No-Loop should be launched with
sufficient number of teams and threads to cover loop iteration space.
No-Loop mode is described in RFC:
https://discourse.llvm.org/t/rfc-no-loop-mode-for-openmp-gpu-kernels/87517/
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Currently, Flang can generate no-loop kernels for all OpenMP target
kernels in the program if the flags
-fopenmp-assume-teams-oversubscription or
-fopenmp-assume-threads-oversubscription are set.
If we add an additional parameter, we can choose
in the future which OpenMP kernels should be generated as no-loop
kernels.
This PR doesn't modify current behavior of oversubscription flags.
RFC for no-loop kernels:
https://discourse.llvm.org/t/rfc-no-loop-mode-for-openmp-gpu-kernels/87517
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Summary:
This patch enables the OpenMP runtime to use the general-purpose
`malloc` interface in `libc` if the user built OpenMP with it enabled.
All this requires is keeping `malloc` as an external function so it will
be resolved later by the linker.
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The generic GPU barrier implementation checked if it was the main thread
in generic mode to identify single threaded regions. This doesn't work
since inside of a non-active (=sequential) parallel, that thread becomes
the main thread of a team, and is not the main thread in generic mode.
At least that is the implementation of the APIs today.
To identify single threaded regions we now check the team size
explicitly.
This exposed three other issues; one is, for now, expected and not a
bug, the second one is a bug and has a FIXME in the
single_threaded_for_barrier_hang_1.c file, and the final one is also
benign as described in the end.
The non-bug issue comes up if we ever initialize a thread state.
Afterwards we will never run any region in parallel. This is a little
conservative, but I guess thread states are really bad for performance
anyway.
The bug comes up if we optimize single_threaded_for_barrier_hang_1 and
execute it in Generic-SPMD mode. For some reason we loose all the
updates to b. This looks very much like a compiler bug, but could also
be another logic issue in the runtime. Needs to be investigated.
Issue number 3 comes up if we have nested parallels inside of a target
region. The clang SPMD-check logic gets confused, determines SPMD (which
is fine) but picks an unreasonable thread count. This is all benign, I
think, just weird:
```
#pragma omp target teams
#pragma omp parallel num_threads(64)
#pragma omp parallel num_threads(10)
{}
```
Was launched with 10 threads, not 64.
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Summary:
We treated the missing kernel environment as a unique mode, but it was
kind of this random bool that was doing the same thing and it explicitly
expects the kernel environment to be zero. It broke after the previous
change since it used to default to SPMD and didn't handle zero in any of
the other cases despite being used. This fixes that and queries for it
without needing to consume an error.
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Summary:
Currently we depend on a single LLVM include directory. This is actually
only required to define one enum, which is highly unlikely to change.
THis patch makes the `Environment.h` include directory more hermetic so
we no long depend on other libraries. In exchange, we get a simpler
dependency list for the price of hard-coding `1` somewhere. I think it's
a valid trade considering that this flag is highly unlikely to change at
this point.
@ronlieb AMD version
https://gist.github.com/jhuber6/3313e6f957be14dc79fe85e5126d2cb3
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(#126143)
Summary:
Currently, we build a single `libomptarget.devicertl.a` which is a
fatbinary. It is a host object file that contains the embedded archive
files for both the NVIDIA and AMDGPU targets. This was done primarily as
a convenience due to naming conflicts. Now that the clang driver for the
GPU targets can appropriate link via the per-target runtime-dir, we can
just make two separate static libraries and remove the indirection.
This patch creates two new static libraries that get installed into
```
/lib/amdgcn-amd-amdhsa/libomp.a
/lib/nvptx64-nvidia-cuda/libomp.a
```
for AMDGPU and NVPTX respectively. The link job created by the linker
wrapper now simply needs to do `-lomp` and it will search those
directories and link those static libraries. This requires far less
special handling.
This patch is a precursor to changing the build system entirely to be a
runtimes based one. Soon this target will be a standard `add_library`
and done through the GPU runtime targets.
NOTE that this actually does remove an additional optimization step.
Previously we merged all of the files into a single bitcode object and
forcibly internalized some definitions. This, instead, just treats them
like a normal static library. This may possibly affect performance for
some files, but I think it's better overall to use static library
semantics because it allows us to have an 'include-what-you-use'
relationship with the library.
Performance testing will be required. If we really need the merged blob
then we can simply pack that into a new static library.
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Summary:
Previously, we removed the special handling for the code object version
global. I erroneously thought that this meant we cold get rid of this
weird `-Xclang` option. However, this also emits an LLVM IR module flag,
which will then cause linking issues.
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This patch removes the addition of 1 to the number of iterations when
calling the following DeviceRTL functions:
- `__kmpc_distribute_for_static_loop*`
- `__kmpc_distribute_static_loop*`
- `__kmpc_for_static_loop*`
Calls to these functions are currently only produced by the OMPIRBuilder
from flang, which already passes the correct number of iterations to
these functions. By adding 1 to the received `num_iters` variable,
worksharing can produce incorrect results. This impacts flang OpenMP
offloading of `do`, `distribute` and `distribute parallel do`
constructs.
Expecting the application to pass `tripcount - 1` as the argument seems
unexpected as well, so rather than updating flang I think it makes more
sense to update the runtime.
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When building with asserts enabled, this can actually cause strange
miscompilations because an incorrect llvm.assume is generated at the
point of the assertion.
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Summary:
Port more instructions. AMD version is at
https://gist.github.com/jhuber6/235d7ee95f747c75f9a3cfd8eedac6aa
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Noticed while extracting the smartstack as a test case
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This reverts commit c02b935a9be888bbdf9f8cb0bf980bd411ae5893.
Failed a check-offload test under CI
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Summary:
This patch ports the runtime to use `gpuintrin.h` instead of calling the
builtins for most things. The `lanemask_gt` stuff was left for now with
a fallback.
AMD version for Ron
https://gist.github.com/jhuber6/42014d635b9a8158727640876bf47226.
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Spirv doesn't have implicit conversions between address spaces (at least
at present, we might need to change that) and address space qualified
*this pointers are not handled well by clang. This commit changes the
single instance of the smartstack to be explicitly a singleton, for
fractionally simpler IR generation (no this pointer) and to sidestep the
work in progress spirv64-- openmp target not being able to compile the
original version.
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Summary:
This definition is more portable since it defines the correct value for
the target. I got rid of the helper mostly because I think it's easy
enough to use now that it's a type and being explicit about what's
`undef` or `poison` is good.
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Summary:
This removes the use of OpenMP offloading to build the device runtime.
The main benefit here is that we no longer need to rely on offloading
semantics to build a device only runtime. Things like variants are now
no longer needed and can just be simple if-defs. In the future, I will
remove most of the special handling here and fold it into calls to the
`<gpuintrin.h>` functions instead. Additionally I will rework the
compilation to make this a separate runtime.
The current plan is to have this, but make including OpenMP and
offloading either automatically add it, or print a warning if it's
missing. This will allow us to use a normal CMake workflow and delete
all the weird 'lets pull the clang binary out of the build' business.
```
-DRUNTIMES_amdgcn-amd-amdhsa_LLVM_ENABLE_RUNTIMES=offload
-DLLVM_RUNTIME_TARGETS=amdgcn-amd-amdhsa
```
After that, linking the OpenMP device runtime will be `-Xoffload-linker
-lomp`. I.e. no more fat binary business.
Only look at the most recent commit since this includes the two
dependencies
(fix to AMDGPUEmitPrintfBinding and the PointerToMember bug).
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https://github.com/codespell-project/codespell
% `codespell
--ignore-words-list=archtype,hsa,identty,inout,iself,nd,te,ths,vertexes
--write-changes`
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(#118661)
Summary:
Currently, we only use `-mlink-builtin-bitcode` for non-LTO NVIDIA
compiliations. This has the problem that it will internalize the RPC
client symbol which needs to be visible to the host. To counteract that,
I put `retain` on it, but this also prevents optimizations on the global
itself, so the passes we have that remove the symbol don't work on
OpenMP anymore. This patch does the dumbest solution, adding a special
string check for it in clang. Not the best solution, the runner up would
be to have a clang attribute for `externally_initialized` because those
can't be internalized, but that might have some unfortunate
side-effects. Alternatively we could make NVIDIA compilations do LTO all
the time, but that would affect some users and it's harder than I
thought.
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Summary:
Right now we just default to device for each type, and mix an ad-hoc
scope with the one used by the compiler's builtins. Unify this can make
each version take the scope optionally.
For @ronlieb, this will remove the need for `add_system` in the fork as
well as the extra `cas` with system scope, just pass `system`.
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Summary:
We used to avoid a lot of this stuff because we didn't properly handle
variadics in device code. That's been solved for now, so we can just
make an internal printf handler that forwards to the external `vprintf`
function. This is either provided by NVIDIA's SDK or by the GPU libc
implementation.
The main reason for doing this is because it prevents the stupid AMDGPU
printf pass from mangling our beautiful printfs!
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Summary:
Use a normal bitcast, remove from the shared utils since it's not
available in
GCC 7.4
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Summary:
Previously we had some indirection here, this patch updates these
utilities to just be normal template functions. We use SFINAE to manage
the special case handling for floats. Also this strips address spaces so
it can be used more generally.
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Summary:
We previously built this for every single architecture to deal with
incompatibility. This patch updates it to use the 'generic' IR that
`libc` and other projects use. Who knows if this will have any
side-effects, probably worth testing more but it passes the tests I
expect to pass on my side.
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Summary:
This is a hack that only NVPTX needs.
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Summary:
This is simpler and more common. I would've replaced the CUDA uses and
made this the same but currently it doesn't codegen these fences fully
and just emits a full system wide barrier as a fallback.
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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.
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Summary:
This is going to be deprecated in
https://github.com/llvm/llvm-project/pull/112849. This patch ports it to
use the builtin instead. This isn't a compile constant, so it could
slightly negatively affect codegen. There really should be an IR pass to
turn it into a constant if the function has known attributes.
Using the builtin is correct when we just do it for knowing the size
like we do here. Obviously guarding w32/w64 code with this check would
be broken.
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Summary:
We define this on AMDGCN but not NVPTX, which leads to some failures
dependong on the target.
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(#100280)
We had three `utils::` namespaces, all with different "meaning" (host,
device, hsa_utils). We should, when we can, keep "include/Shared"
accessible from host and device, thus RefCountTy has been moved to a
separate header. `hsa_utils` was introduced to make `utils::` less
overloaded. And common functionality was de-duplicated, e.g.,
`utils::advance` and `utils::advanceVoidPtr` -> `utils:advancePtr`. Type
punning now checks for the size of the result to make sure it matches
the source type.
No functional change was intended.
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This pull request is a revised version of #76587. This pull request
fixes some build issues that were present in the previous version of
this change.
> This pull request is the first part of an ongoing effort to extends
PGO instrumentation to GPU device code. This PR makes the following
changes:
>
> - Adds blank registration functions to device RTL
> - Gives PGO globals protected visibility when targeting a supported
GPU
> - Handles any addrspace casts for PGO calls
> - Implements PGO global extraction in GPU plugins (currently only
dumps info)
>
> These changes can be tested by supplying `-fprofile-instrument=clang`
while targeting a GPU.
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Summary:
The 'omp_alloc' function should be callable from a target region. This
patch implemets it by simply calling `malloc` for every non-default
trait value allocator. All the special access modifiers are
unimplemented and return null. The null allocator returns null as the
spec states it should not be usable from the target.
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This reverts commit fea5914c926e2f013a8b5e27eaa74c7047fb2c71.
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This reverts commit 069e8bcd82c4420239f95c7e6a09e1f756317cfc.
Summary:
Some tests failing, revert this for now.
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Summary:
Currently there are several layers to handle `printf`. Since we now have
varargs and an implementation of `printf` this can be heavily
simplified.
1. The frontend renames `printf` into `omp_vprintf` and gives it an
argument buffer.
Removing 1. triggered some code in the AMDGPU backend menat for HIP /
OpenCL, so I hadded an exception to it.
2. Forward this to CUDA vprintf or ignore it.
We no longer need special handling for it since we have varargs. So now
we just forward this to CUDA vprintf if we have libc, otherwise just
leave `printf` as an external function and expect that `libc` will be
linked in.
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Summary:
The C library is intended to provide `__assert_fail`, so in the cases
that we have both we should defer to that. This means that if you build
the C library for GPUs you'll get the RPC based asser, and if not you'll
get the trap based one.
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Summary:
These functions provide special-case implementations internal to the
OpenMP device runtime. This can potentially conflict with the symbols
pulled in from the actual GPU `libc`. This patch makes these weak, so in
the case that the GPU libc functions exist they will be overridden. This
should not impact performance in the average case because the old
`-mlink-builtin-bitcode` version does internalization, deleting weak,
and the new LTO path will resolve to the strong reference and then
internalize it.
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This patch fixes the dynamic schedule tracking.
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This reverts commit 5fd2af38e461445c583d7ffc2fe23858966eee76. It caused build issues and broke the buildbot.
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This pull request is the first part of an ongoing effort to extends PGO
instrumentation to GPU device code. This PR makes the following changes:
- Adds blank registration functions to device RTL
- Gives PGO globals protected visibility when targeting a supported GPU
- Handles any addrspace casts for PGO calls
- Implements PGO global extraction in GPU plugins (currently only dumps
info)
These changes can be tested by supplying `-fprofile-instrument=clang`
while targeting a GPU.
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This reverts commit 7b4865582299294455bc816358fd88a9c6e5e0be.
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This reverts commit 9b31cc71d66064dfaf2afabf4a835211321bb4a0.
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This reverts commit 098c6dfa8157681699a71fce9e3d94515e66311f.
This reverts commit 8c718a3a91df4ab68dc3f1ca3887ea730c9aed84.
This reverts commit 4fb02de9d490d0773441aa30124bb4d1272230d3.
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This patch adds the support for `ballot_sync` in ompx.
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