Replaced CUDA builtin vars with LLVM intrinsics such that we don't need
definitions of those intrinsics.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D95013
[libomptarget][devicertl] Wrap source in declare target pragmas
Factored out of D93135 / D94745. C++ and cuda ignore unknown pragmas
so this is a NFC for the current implementation language. Removes noise
from patches for building deviceRTL as openmp.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D95048
[libomptarget][nvptx] Reduce calls to cuda header
Remove use of clock_t in favour of a builtin. Drop a preprocessor branch.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D94731
[libomptarget][nvptx][nfc] Move target_impl functions out of header
This removes most of the differences between the two target_impl.h.
Also change name mangling from C to C++ for __kmpc_impl_*_lock.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D94728
`omptarget-nvptx` is still a dependence for `check-libomptarget-nvtpx`
although it has been removed by D94573.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D94725
The comment said CUDA 9 header files use the `nv_weak` attribute which
`clang` is not yet prepared to handle. It's three years ago and now things have
changed. Based on my test, removing the definition doesn't have any problem on
my machine with CUDA 11.1 installed.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D94700
For NVPTX target, OpenMP provides a static library `libomptarget-nvptx`
built by NVCC, and another bitcode `libomptarget-nvptx-sm_{$sm}.bc` generated by
Clang. When compiling an OpenMP program, the `.bc` file will be fed to `clang`
in the second run on the program that compiles the target part. Then the generated
PTX file will be fed to `ptxas` to generate the object file, and finally the driver
invokes `nvlink` to generate the binary, where the static library will be appened
to `nvlink`.
One question is, why do we need two libraries? The only difference is, the static
library contains `omp_data.cu` and the bitcode library doesn't. It's unclear why
they were implemented in this way, but per D94565, there is no issue if we also
include the file into the bitcode library. Therefore, we can safely drop the
static library.
This patch is about the change in OpenMP. The driver will be updated as well if
this patch is accepted.
Reviewed By: jdoerfert, JonChesterfield
Differential Revision: https://reviews.llvm.org/D94573
Restore control of kernel launch tracing to be >= 1 as it was before
export LIBOMPTARGET_KERNEL_TRACE=1
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D94695
Constant static data member can be defined in the class without another
define after the class in C++17. Although it is C++17, Clang can still handle it
even w/o the flag for C++17. Unluckily, GCC cannot handle that.
Reviewed By: jhuber6
Differential Revision: https://reviews.llvm.org/D94541
[libomptarget][amdgpu][nfc] Fix build on centos
rtl.cpp replaced 224 with a #define from elf.h, but that
doesn't work on a centos 7 build machine with an old elf.h
Reviewed By: ronlieb
Differential Revision: https://reviews.llvm.org/D94528
Some LLVM headers are generated by CMake. Before the installation,
LLVM's headers are distributed everywhere, some of which are in
`${LLVM_SRC_ROOT}/llvm/include/llvm`, and some are in
`${LLVM_BINARY_ROOT}/include/llvm`. After intallation, they're all in
`${LLVM_INSTALLATION_ROOT}/include/llvm`.
OpenMP now depends on LLVM headers. Some headers depend on headers generated
by CMake. When building OpenMP along with LLVM, a.k.a via `LLVM_ENABLE_RUNTIMES`,
we need to tell OpenMP where it can find those headers, especially those still
have not been copied/installed.
Reviewed By: jdoerfert, jhuber6
Differential Revision: https://reviews.llvm.org/D94534
The lifetime of `libomptarget` and its opened plugins are not aligned
and it's hard for `libomptarget` to determine when the plugins are destroyed.
As a result, some issues (see D94256 for details) occur on some platforms.
Actually, if we take target memory as target resources, same as other resources,
such as CUDA streams, in each plugin, then the memory manager should also be in
the plugin. Also considering some platforms may want to opt out the feature, it
makes sense to move the memory manager to plugin, make it a common interface, and
let plguin developers determine whether they need it. This is what this patch does.
CUDA plugin is taken as example to show how to integrate it. In this way, we can
also get a bonus that different thresholds can be set for different platforms.
Reviewed By: jdoerfert, JonChesterfield
Differential Revision: https://reviews.llvm.org/D94379
For now `elf_common.c` is taken as a common part included into
different plugin implementations directly via
`#include "../../common/elf_common.c"`, which is not a best practice. Since it
is simple enough such that we don't need to create a real library for it, we just
take it as a interface library so that other targets can link it directly. Another
advantage of this method is, we don't need to add the folder into header search
path which can potentially pollute the search path.
VE and AMD platforms have not been tested because I don't have target machines.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D94443
Multiple `RTLInfoTy` objects are stored in a list `AllRTLs`. Since
`RTLInfoTy` contains a `std::mutex`, it is by default not a copyable object.
In order to support `AllRTLs.push_back(...)` which is currently used, a customized
copy constructor is provided. Every time we need to add a new data member into
`RTLInfoTy`, we should keep in mind not forgetting to add corresponding assignment
in the copy constructor. In fact, the only use of the copy constructor is to push
the object into the list, we can of course write it in a way that first emplace
a new object back, and then use the reference to the last element. In this way we
don't need the copy constructor anymore. If the element is invalid, we just need
to pop it, and that's what this patch does.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D94361
Summary:
Currently error messages from the CUDA plugins are only printed to the user if they have debugging enabled. Change this behaviour to always print the messages that result in offloading failure. This improves the error messages by indidcating what happened when the error occurs in the plugin library, such as a segmentation fault on the device.
Reviewed by: jdoerfert
Differential Revision: https://reviews.llvm.org/D94263
Wrong LLVM headers might be included if we don't set `include_directories`
to a right place. This will cause a compilation error if LLVM is installed in
system directories.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D93737
Currently all built libraries in OpenMP are anywhere if building along
with LLVM. It is not an issue if we don't execute any test. However, almost all
tests for `libomptarget` fails because in the lit configuration, we only set
`<build_dir>/libomptarget` to `LD_LIBRARY_PATH` and `LIBRARY_PATH`. Since those
libraries are everywhere, `clang` can no longer find `libomptarget.so` or those
deviceRTLs anymore.
In this patch, we set a unified path for all built libraries, no matter whether
it is built along with LLVM or not. In this way, our lit configuration can work
propoerly.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D93736
Summary:
This patch adds more fine-grained support over which information is output from the libomptarget runtime when run with the environment variable LIBOMPTARGET_INFO set. An extensible set of flags can be used to pick and choose which information the user is interested in.
Reviewers: jdoerfert JonChesterfield grokos
Differential Revision: https://reviews.llvm.org/D93727
[libomptarget][amdgpu] Call into deviceRTL instead of ockl
Amdgpu codegen presently emits a call into ockl. The same functionality
is already present in the deviceRTL. Adds an amdgpu specific entry point
to avoid the dependency. This lets simple openmp code (specifically, that
which doesn't use libm) run without rocm device libraries installed.
Reviewed By: ronlieb
Differential Revision: https://reviews.llvm.org/D93356
This patchs adds CMake variables to add subdirectories and include
directories for libomptarget and explicitly gives the location of source
files.
Differential Revision: https://reviews.llvm.org/D93290
[libomptarget][nfc] Replace static const with enum
Semantically identical. Replaces 0xff... with ~0 to spare counting the f.
Has the advantage that the compiler doesn't need to prove the 4/8 byte
value dead before discarding it, and sidesteps the compilation question
associated with what static means for a single source language.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D93328
[libomptarget][nfc] Remove data_sharing type aliasing
Libomptarget previous used __kmpc_data_sharing_slot to access values of type
__kmpc_data_sharing_{worker,master}_slot_static. This aliasing violation was
benign in practice. The master type has since been removed, so a single type
can be used instead.
This is particularly helpful for the transition to an openmp deviceRTL, as the
c++/openmp compiler for amdgcn currently rejects the flexible array member for
being an incomplete type. Serves the same purpose as abandoned D86324.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D93075
[libomptarget][amdgpu] Address compiler warnings, drive by fixes
Initialize some variables, remove unused ones.
Changes the debug printing condition to align with the aomp test suite.
Differential Revision: https://reviews.llvm.org/D92559
[libomptarget][cuda] Detect missing symbols in plugin at build time
Passes -z,defs to the linker. Error on unresolved symbol references.
Otherwise, those unresolved symbols present as target code running on the host
as the plugin fails to load. This is significantly harder to debug than a link
time error. Flag matches that passed by amdgcn and ve plugins.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D92143
This patch is the runtime support for https://reviews.llvm.org/D84192.
In order not to modify the tgt_target_data_update information but still be
able to pass the extra information for non-contiguous map item (offset,
count, and stride for each dimension), this patch overload arg when
the maptype is set as OMP_TGT_MAPTYPE_DESCRIPTOR. The origin arg is for
passing the pointer information, however, the overloaded arg is an
array of descriptor_dim:
```
struct descriptor_dim {
int64_t offset;
int64_t count;
int64_t stride
};
```
and the array size is the dimension size. In addition, since we
have count and stride information in descriptor_dim, we can replace/overload the
arg_size parameter by using dimension size.
Reviewed By: grokos, tianshilei1992
Differential Revision: https://reviews.llvm.org/D82245
Summary:
Add support for passing source locations to libomptarget runtime functions using the ident_t struct present in the rest of the libomp API. This will allow the runtime system to give much more insightful error messages and debugging values.
Reviewers: jdoerfert grokos
Differential Revision: https://reviews.llvm.org/D87946
Summary:
This patch adds basic support for priting the source location and names for the mapped variables. This patch does not support names for custom mappers. This is based on D89802.
Reviewers: jdoerfert
Differential Revision: https://reviews.llvm.org/D90172
Summary:
This patch adds support for passing in the original delcaration name in the source file to the libomptarget runtime. This will allow the runtime to provide more intelligent debugging messages. This patch takes the original expression parsed from the OpenMP map / update clause and provides a textual representation if it was explicitly mapped, otherwise it takes the name of the variable declaration as a fallback. The information in passed to the runtime in a global array of strings that matches the existing ident_t source location strings using ";name;filename;column;row;;"
Reviewers: jdoerfert
Differential Revision: https://reviews.llvm.org/D89802
This patch is the runtime support for https://reviews.llvm.org/D84192.
In order not to modify the tgt_target_data_update information but still be
able to pass the extra information for non-contiguous map item (offset,
count, and stride for each dimension), this patch overload arg when
the maptype is set as OMP_TGT_MAPTYPE_DESCRIPTOR. The origin arg is for
passing the pointer information, however, the overloaded arg is an
array of descriptor_dim:
```
struct descriptor_dim {
int64_t offset;
int64_t count;
int64_t stride
};
```
and the array size is the dimension size. In addition, since we
have count and stride information in descriptor_dim, we can replace/overload the
arg_size parameter by using dimension size.
Reviewed By: grokos
Differential Revision: https://reviews.llvm.org/D82245
There is a non-conforming use of variable-sized array in the test case `parallel_offloading_map.c`. This patch fixed it.
Reviewed By: protze.joachim
Differential Revision: https://reviews.llvm.org/D90642
Presently, there a number of global variables in libomptarget (devices,
RTLs, tables, mutexes, etc.) that are not placed within a struct. This
patch places them into a struct ``PluginManager``. All of the functions
that act on this data remain free.
Differential Revision: https://reviews.llvm.org/D90519
[AMDGPU] Add __builtin_amdgcn_grid_size
Similar to D76772, loads the data from the dispatch pointer. Marked invariant.
Patch also updates the openmp devicertl to use this builtin.
Reviewed By: yaxunl
Differential Revision: https://reviews.llvm.org/D90251
Summary:
This patch adds basic support for priting the source location and names for the
mapped variables. This patch does not support names for custom mappers. This is
based on D89802. The names information currently will be printed out only in
debug mode or using env LIBOMPTARGET_INFO during execution. But the information
is added when availible to the Device and Private data structures. To get the
information out the code must be built with debug symbols on using -g or
-Rpass=openmp-opt
Reviewers: jdoerfert
Differential Revision: https://reviews.llvm.org/D90172
Summary:
This patch adds support for passing in the original delcaration name in the
source file to the libomptarget runtime. This will allow the runtime to provide
more intelligent debugging messages. This patch takes the original expression
parsed from the OpenMP map / update clause and provides a textual
representation if it was explicitly mapped, otherwise it takes the name of the
variable declaration as a fallback. The information in passed to the runtime in
a global array of strings that matches the existing ident_t source location
strings using ";name;filename;column;row;;". See
clang/test/OpenMP/target_map_names.cpp for an example of the generated output
for a given map clause.
Reviewers: jdoervert
Differential Revision: https://reviews.llvm.org/D89802
The implementation of target nowait just wraps the target region into a task. The essential four parameters (base ptr, ptr, size, mapper) are taken as firstprivate such that they will be copied to the private location. When there is no user-defined mapper, the mapper variable will be nullptr. However, it will be still copied to the corresponding place. Therefore, a memcpy will be generated and the source pointer will be nullptr, causing a segmentation fault. The root cause is when calling `emitOffloadingArraysArgument`, the last argument `Options` has a field about whether it requires a task. It only takes depend clause into account. In this patch, the nowait clause is also included.
There're two things that will be done in another patches:
1. target data nowait has not been supported yet. D90099 added the support.
2. When there is no mapper, the mapper array can be nullptr no matter whether it requires outer task or not. It can avoid an unnecessary data copy. This is an optimization that is covered in D90101.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D89844
`size_t` has different width on 32- and 64-bit architecture, but the
computation to floor to power of two assumed it is 64-bit, which can cause an
integer overflow. In this patch, architecture detection is added so that the
operation for 64-bit `size_t`. Thank Luke for reporting the issue.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D89878
[libomptarget] Require LLVM source tree to build libomptarget
This is to permit reliably #including files from the LLVM tree in libomptarget,
as an improvement on the copy and paste that is currently in use. See D87841
for the first example of removing duplication given this new requirement.
The weekly openmp dev call reached consensus on this approach. See also D87841
for some alternatives that were considered. In the future, we may want to
introduce a new top level repo for shared constants, or start using the ADT
library within openmp.
This will break sufficiently exotic build systems, trivial fixes as below.
Building libomptarget as part of the monorepo will continue to work.
If openmp is built separately, it now requires a cmake macro indicating
where to find the LLVM source tree.
If openmp is built separately, without the llvm source tree already on disk,
the build machine will need a copy of a subset of the llvm source tree and
the cmake macro indicating where it is.
Reviewed By: protze.joachim
Differential Revision: https://reviews.llvm.org/D89426
[libomptarget][amdgcn] Refactor memcpy to eliminate maps
Builds on D89776 to remove now dead code.
Reviewed By: pdhaliwal
Differential Revision: https://reviews.llvm.org/D89888
The calls to atmi_memcpy presently determine the direction of copy (host to
device or device to host) by storing pointers in a map during malloc and
looking up the pointers during memcpy. As each call site already knows the
direction, this stash+lookup can be eliminated.
This NFC will be followed by a functional one that deletes those map lookups.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D89776
Change-Id: I1d9089bc1e56b3a9a30e334735fa07dee1f84990
[libomptarget][amdgcn] Implement missing symbols in deviceRTL
Malloc, wtime are stubs. Malloc needs a hostrpc implementation which is
a work in progress, wtime needs some experimentation to find out the
multiplier to get a time in seconds as documentation is scarce.
Reviewed By: ronlieb
Differential Revision: https://reviews.llvm.org/D89725
This patch fixes a problem whereby the pointee object of a PTR_AND_OBJ entry with a `map(to)` motion clause can be overwritten on the device even if its reference counter is >=1.
Currently, we check the reference counter of the parent struct in order to determine whether the motion clause should be respected, but since the pointee object is not part of the struct, it's got its own reference counter which should be used to enqueue the copy or discard it.
The same behavior has already been implemented in targetDataEnd (omptarget.cpp:539-540), but we somehow missed doing the same in targetDataBegin.
Differential Revision: https://reviews.llvm.org/D89597
[openmp][libomptarget] Include header from LLVM source tree
The change is to the amdgpu plugin so is unlikely to break anything.
The point of contention is whether libomptarget can depend on LLVM.
A community discussion was cautiously not opposed yesterday.
This introduces a compile time dependency on the LLVM source tree, in this case
expressed as skipping the building of the plugin if LLVM_MAIN_INCLUDE_DIR is not
set. One the source files will #include llvm/Frontend/OpenMP/OMPGridValues.h,
instead of copy&pasting the numbers across.
For users that download the monorepo, the llvm tree is already on disk. This will
inconvenience users who download only the openmp source as a tar, as they would
now also have to download (at least a file or two) from the llvm source, if they want
to build the parts of the openmp project that (post this patch) depend on llvm.
There was interest expressed in going further - using llvm tools as part of
building libomp, or linking against llvm libraries. That seems less clear cut
an improvement and worthy of further discussion. This patch seeks only to change
policy to support openmp depending on the llvm source tree. Including in the
other direction, or using libraries / tools etc, are purposefully out of scope.
Reviewers are a best guess at interested parties, please feel free to add others
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D87841
[libomptarget][amdgcn] Implement partial barrier
named_sync is used to coordinate non-spmd kernels. This uses bar.sync on nvptx.
There is no corresponding ISA support on amdgcn, so this is implemented using
shared memory, one word initialized to zero.
Each wave increments the variable by one. Whichever wave is last is responsible
for resetting the variable to zero, at which point it and the others continue.
The race condition on a wave reaching the barrier before another wave has
noticed that it has been released is handled with a generation counter, packed
into the same word.
Uses a shared variable that is not needed on nvptx. Introduces a new hook,
kmpc_impl_target_init, to allow different targets to do extra initialization.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D88602
Summary:
This patch changes the CMake files for Clang and Libomptarget to query the
system for its supported CUDA architecture. This makes it much easier for the
user to build optimal code without needing to set the flags manually. This
relies on the now deprecated FindCUDA method in CMake, but full support for
architecture detection is only availible in CMake >3.18
Reviewers: jdoerfert ye-luo
Subscribers: cfe-commits guansong mgorny openmp-commits sstefan1 yaxunl
Tags: #clang #OpenMP
Differential Revision: https://reviews.llvm.org/D87946
OpenMP 5.1 defines omp_get_initial_device to return the same value as omp_get_num_devices.
Since this change is also 5.0 compliant, no versioning is needed.
Differential Revision: https://reviews.llvm.org/D88149
[nfc][libomptarget] Drop parameter to named_sync
named_sync has one call site (in sync.cu) where it always passed L1_BARRIER.
Folding this into the call site and dropping the macro is a simplification.
amdgpu doesn't have ptx' bar.sync instruction. A correct implementation of
__kmpc_impl_named_sync in terms of shared memory is much easier if it can
assume that the barrier argument is this constant. Said implementation is left
for a second patch.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D88474
It allows customizing MAX_SM for non-flagship GPU and reduces graphic memory usage.
In addition, so far the size is hard-coded up to __CUDA_ARCH__ 700 and is already a hassle for 800.
Introduce MAX_SM for 800 and protect future arch
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D88185
If an error code can not be recognized by cuGetErrorString, errStr remains null and causes crashing at DP() printing.
Protect this case.
Reviewed By: jhuber6, tianshilei1992
Differential Revision: https://reviews.llvm.org/D87980
Summary:
This patch adds additonal support for priting infromation from Libomptarget for
already existing maps and printing the final data mapped on the device at
device destruction.
Reviewers: jdoerfort gkistanova
Subscribers: guansong openmp-commits sstefan1 yaxunl
Tags: #OpenMP
Differential Revision: https://reviews.llvm.org/D87722
Summary:
This patch starts adding support for adding information dumps to libomptarget
and rtl plugins. The information printing is controlled by the
LIBOMPTARGET_INFO environment variable introduced in D86483. The goal of this
patch is to provide the user with additional information about the device
during kernel execution and providing the user with information dumps in the
case of failure. This patch added the ability to dump the pointer mapping table
as well as printing the number of blocks and threads in the cuda RTL.
Reviewers: jdoerfort gkistanova ye-luo
Subscribers: guansong openmp-commits sstefan1 yaxunl ye-luo
Tags: #OpenMP
Differential Revision: https://reviews.llvm.org/D87165
The size of worker_rootS should have been DS_Max_Warp_Number.
This reduces memory usage by deviceRTL on AMDGPU from around 2.3GB
to around 770MB.
Reviewed By: JonChesterfield, jdoerfert
Differential Revision: https://reviews.llvm.org/D87084
Summary:
This patch consolidates the error handling and messaging routines to a single
file omptargetmessage. The goal is to simplify the error handling interface
prior to adding more error handling support
Reviewers: jdoerfert grokos ABataev AndreyChurbanov ronlieb JonChesterfield ye-luo tianshilei1992
Subscribers: danielkiss guansong jvesely kerbowa nhaehnle openmp-commits sstefan1 yaxunl
PrivateArgumentManager shall immediately allocate firstprivates if they
are bases for the next parameters and the next paramaters rely on the
fact that the base musst be allocated already.
Differential Revision: https://reviews.llvm.org/D86781
The test command in `private_mapping.c` was set to expect failure by mistake. It is fixed in this patch.
Reviewed By: ABataev
Differential Revision: https://reviews.llvm.org/D86758
Summary:
This patch changes the libomptarget runtime to always emit debug messages that
occur before offloading failure. The goal is to provide users with information
about why their application failed in the target region rather than a single
failure message. This is only done in regions that precede offloading failure
so this should not impact runtime performance. if the debug environment
variable is set then the message is forwarded to the debug output as usual.
A new environment variable was added for future use but does nothing in this
current patch. LIBOMPTARGET_INFO will be used to report runtime information to
the user if requrested, such as grid size, SPMD usage, or data mapping. It will
take an integer indicating the level of information verbosity and a value of 0
will disable it.
Reviewers: jdoerfort
Subscribers: guansong sstefan1 yaxunl ye-luo
Tags: #OpenMP
Differential Revision: https://reviews.llvm.org/D86483
In this patch, we pack all small first-private arguments, allocate and transfer them all at once to reduce the number of data transfer which is very expensive.
Let's take the test case as example.
```
int main() {
int data1[3] = {1}, data2[3] = {2}, data3[3] = {3};
int sum[16] = {0};
#pragma omp target teams distribute parallel for map(tofrom: sum) firstprivate(data1, data2, data3)
for (int i = 0; i < 16; ++i) {
for (int j = 0; j < 3; ++j) {
sum[i] += data1[j];
sum[i] += data2[j];
sum[i] += data3[j];
}
}
}
```
Here `data1`, `data2`, and `data3` are three first-private arguments of the target region. In the previous `libomptarget`, it called data allocation and data transfer three times, each of which allocated and transferred 12 bytes. With this patch, it only calls allocation and transfer once. The size is `(12+4)*3=48` where 12 is the size of each array and 4 is the padding to keep the address aligned with 8. It is implemented in this way:
1. First collect all information for those *first*-private arguments. _private_ arguments are not the case because private arguments don't need to be mapped to target device. It just needs a data allocation. With the patch for memory manager, the data allocation could be very cheap, especially for the small size. For each qualified argument, push a place holder pointer `nullptr` to the `vector` for kernel arguments, and we will update them later.
2. After we have all information, create a buffer that can accommodate all arguments plus their paddings. Copy the arguments to the buffer at the right place, i.e. aligned address.
3. Allocate a target memory with the same size as the host buffer, transfer the host buffer to target device, and finally update all place holder pointers in the arguments `vector`.
The reason we only consider small arguments is, the data transfer is asynchronous. Therefore, for the large argument, we could continue to do things on the host side meanwhile, hopefully, the data is also being transferred. The "small" is defined by that the argument size is less than a predefined value. Currently it is 1024. I'm not sure whether it is a good one, and that is an open question. Another question is, do we need to make it configurable via an environment variable?
Reviewed By: ye-luo
Differential Revision: https://reviews.llvm.org/D86307
Target memory manager is introduced in this patch which aims to manage target
memory such that they will not be freed immediately when they are not used
because the overhead of memory allocation and free is very large. For CUDA
device, cuMemFree even blocks the context switch on device which affects
concurrent kernel execution.
The memory manager can be taken as a memory pool. It divides the pool into
multiple buckets according to the size such that memory allocation/free
distributed to different buckets will not affect each other.
In this version, we use the exact-equality policy to find a free buffer. This
is an open question: will best-fit work better here? IMO, best-fit is not good
for target memory management because computation on GPU usually requires GBs of
data. Best-fit might lead to a serious waste. For example, there is a free
buffer of size 1960MB, and now we need a buffer of size 1200MB. If best-fit,
the free buffer will be returned, leading to a 760MB waste.
The allocation will happen when there is no free memory left, and the memory
free on device will take place in the following two cases:
1. The program ends. Obviously. However, there is a little problem that plugin
library is destroyed before the memory manager is destroyed, leading to a fact
that the call to target plugin will not succeed.
2. Device is out of memory when we request a new memory. The manager will walk
through all free buffers from the bucket with largest base size, pick up one
buffer, free it, and try to allocate immediately. If it succeeds, it will
return right away rather than freeing all buffers in free list.
Update:
A threshold (8KB by default) is set such that users could control what size of memory
will be managed by the manager. It can also be configured by an environment variable
`LIBOMPTARGET_MEMORY_MANAGER_THRESHOLD`.
Reviewed By: jdoerfert, ye-luo, JonChesterfield
Differential Revision: https://reviews.llvm.org/D81054
This patch contains the following changes:
1. Renamed the function `DeviceTy::data_exchange` to `DeviceTy::dataExchange`;
2. Changed the second argument `DeviceTy DstDev` to `DeviceTy &DstDev`;
3. Renamed the last argument.
Reviewed By: ye-luo
Differential Revision: https://reviews.llvm.org/D86238
Instead of calling `cuFuncGetAttribute` with
`CU_FUNC_ATTRIBUTE_MAX_THREADS_PER_BLOCK` for every kernel invocation,
we can do it for the first one and cache the result as part of the
`KernelInfo` struct. The only functional change is that we now expect
`cuFuncGetAttribute` to succeed and otherwise propagate the error.
Ignoring any error seems like a slippery slope...
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D86038
[libomptarget] Implement host plugin for amdgpu
Replacement for D71384. Primary difference is inlining the dependency on atmi
followed by extensive simplification and bugfixes. This is the latest version
from https://github.com/ROCm-Developer-Tools/amd-llvm-project/tree/aomp12 with
minor patches and a rename from hsa to amdgpu, on the basis that this can't be
used by other implementations of hsa without additional work.
This will not build unless the ROCM_DIR variable is passed so won't break other
builds. That variable is used to locate two amdgpu specific libraries that ship
as part of rocm:
libhsakmt at https://github.com/RadeonOpenCompute/ROCT-Thunk-Interface
libhsa-runtime64 at https://github.com/RadeonOpenCompute/ROCR-Runtime
These libraries build from source. The build scripts in those repos are for
shared libraries, but can be adapted to statically link both into this plugin.
There are caveats.
- This works well enough to run various tests and benchmarks, and will be used
to support the current clang bring up
- It is adequately thread safe for the above but there will be races remaining
- It is not stylistically correct for llvm, though has had clang-format run
- It has suboptimal memory management and locking strategies
- The debug printing / error handling is inconsistent
I would like to contribute this pretty much as-is and then improve it in-tree.
This would be advantagous because the aomp12 branch that was in use for fixing
this codebase has just been joined with the amd internal rocm dev process.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D85742
For example:
```
#pragma omp target data map(tofrom:arr[0:100])
{
#pragma omp target exit data map(delete:arr[0:100])
#pragma omp target enter data map(alloc:arr[98:2])
}
```
Without this patch, the transfer at the end of the target data region
is broken and fails depending on the target device. According to my
read of the spec, the transfer shouldn't even be attempted because
`arr[0:100]` isn't (fully) present there. To fix that, this patch
makes `DeviceTy::getTgtPtrBegin` return null for this case.
Reviewed By: grokos
Differential Revision: https://reviews.llvm.org/D85342
For example, without this patch, the following fails as expected with
or without the `present` modifier, but the `present` modifier doesn't
produce its usual diagnostic:
```
#pragma omp target data map(alloc: arr[0:2])
{
#pragma omp target map(present, tofrom: arr[0:100]) // not fully present
;
}
```
Reviewed By: grokos, vzakhari
Differential Revision: https://reviews.llvm.org/D85320
The standard way of printing `int64_t` data is via the PRId64 macro, `ld`
is for `long int` and int64_t is not guaranteed to be typedef'ed as `long int`
on all platforms. E.g. on Windows we get mismatch warnings.
Differential Revision: https://reviews.llvm.org/D85353
targetDataMapper function fills arrays with the mapping data in the
direct order. When this function is called by targetDataBegin or
tgt_target_update functions, it works as expected. But targetDataEnd
function processes mapped data in reverse order. In this case, the base
pointer might be deleted before the associated data is deleted. Need to
reverse data, mapped by mapper, too, since it always adds data that must
be deleted at the end of the buffer.
Fixes the test declare_mapper_target_update.cpp.
Also, reduces the memry fragmentation by preallocation the memory
buffers.
Differential Revision: https://reviews.llvm.org/D85216
OpenMP TR8 sec. 2.15.6 "target update Construct", p. 183, L3-4 states:
> If the corresponding list item is not present in the device data
> environment and there is no present modifier in the clause, then no
> assignment occurs to or from the original list item.
L10-11 states:
> If a present modifier appears in the clause and the corresponding
> list item is not present in the device data environment then an
> error occurs and the program termintates.
(OpenMP 5.0 also has the first passage but without mention of the
present modifier of course.)
In both passages, I assume "is not present" includes the case of
partially but not entirely present. However, without this patch, the
target update directive misbehaves in this case both with and without
the present modifier. For example:
```
#pragma omp target enter data map(to:arr[0:3])
#pragma omp target update to(arr[0:5]) // might fail on data transfer
#pragma omp target update to(present:arr[0:5]) // might fail on data transfer
```
The problem is that `DeviceTy::getTgtPtrBegin` does not return a null
pointer in that case, so `target_data_update` sees the data as fully
present, and the data transfer then might fail depending on the target
device. However, without the present modifier, there should never be
a failure. Moreover, with the present modifier, there should always
be a failure, and the diagnostic should mention the present modifier.
This patch fixes `DeviceTy::getTgtPtrBegin` to return null when
`target_data_update` is the caller. I'm wondering if it should do the
same for more callers.
Reviewed By: grokos, jdoerfert
Differential Revision: https://reviews.llvm.org/D85246
Without this patch, the following example fails but shouldn't
according to OpenMP TR8:
```
#pragma omp target enter data map(alloc:i)
#pragma omp target data map(present, alloc: i)
{
#pragma omp target exit data map(delete:i)
} // fails presence check here
```
OpenMP TR8 sec. 2.22.7.1 "map Clause", p. 321, L23-26 states:
> If the map clause appears on a target, target data, target enter
> data or target exit data construct with a present map-type-modifier
> then on entry to the region if the corresponding list item does not
> appear in the device data environment an error occurs and the
> program terminates.
There is no corresponding statement about the exit from a region.
Thus, the `present` modifier should:
1. Check for presence upon entry into any region, including a `target
exit data` region. This behavior is already implemented correctly.
2. Should not check for presence upon exit from any region, including
a `target` or `target data` region. Without this patch, this
behavior is not implemented correctly, breaking the above example.
In the case of `target data`, this patch fixes the latter behavior by
removing the `present` modifier from the map types Clang generates for
the runtime call at the end of the region.
In the case of `target`, we have not found a valid OpenMP program for
which such a fix would matter. It appears that, if a program can
guarantee that data is present at the beginning of a `target` region
so that there's no error there, that data is also guaranteed to be
present at the end. This patch adds a comment to the runtime to
document this case.
Reviewed By: grokos, RaviNarayanaswamy, ABataev
Differential Revision: https://reviews.llvm.org/D84422
This patch fixed the issue that target memory might be deallocated when
they're still being used or before they're used.
Reviewed By: ye-luo
Differential Revision: https://reviews.llvm.org/D84996
Refactored the function `targetDataEnd` to make preparation of fixing
the issue of ahead-of-time target memory deallocation. This patch only
renamed `targetDataEnd` related variables and functions to conform
with LLVM code standard.
Reviewed By: ye-luo
Differential Revision: https://reviews.llvm.org/D84991
Refactored the function `target` to make preparation for fixing the
issue of ahead-of-time device memory deallocation.
Reviewed By: ye-luo
Differential Revision: https://reviews.llvm.org/D84816
Need to map the base pointer for all directives, not only target
data-based ones.
The base pointer is mapped for array sections, array subscript, array
shaping and other array-like constructs with the base pointer. Also,
codegen for use_device_ptr clause was modified to correctly handle
mapping combination of array like constructs + use_device_ptr clause.
The data for use_device_ptr clause is emitted as the last records in the
data mapping array.
Reviewed By: ye-luo
Differential Revision: https://reviews.llvm.org/D84767
Need to map the base pointer for all directives, not only target
data-based ones.
The base pointer is mapped for array sections, array subscript, array
shaping and other array-like constructs with the base pointer. Also,
codegen for use_device_ptr clause was modified to correctly handle
mapping combination of array like constructs + use_device_ptr clause.
The data for use_device_ptr clause is emitted as the last records in the
data mapping array.
It applies only for global pointers.
Differential Revision: https://reviews.llvm.org/D84767
This patch implements OpenMP runtime support for the OpenMP TR8
`present` motion modifier for `omp target update` directives. The
previous patch in this series implements Clang front end support.
Reviewed By: grokos
Differential Revision: https://reviews.llvm.org/D84712
Shilei Tian