This patch ensures the `IsGPU` flag is set by the OpenMPOpt pass, so
that it can be relied upon by `OpenMPIRBuilder` methods when called by
that pass as well.
Since currently there are very limited callers for the
`OpenMPIRBuilder::isGPU()` method, no assertions are being triggered by
the lack of initialization of this flag. However, when more
offloading-related features are implemented, it will eventually start
happening.
If we can't transform the region to SPMD, we should not wait till the
end to decide that. Other AAs might assume SPMD, and we did set the
constant initializer to indicate SPMD, but we did not change the code
properly.
This reverts commit e592c2dcf5b7d2da6c2564f5d9990aa34079bad4.
We can finally reland the PR since the issue that caused the PR to be
reverted has been resolved in
https://github.com/llvm/llvm-project/pull/104051.
We don't have any legacy pass manager CGSCC passes that modify the call
graph (we only use it in the codegen pipeline to run function passes in
call graph order). This is the beginning of removing CallGraphUpdater
and making all the relevant CGSCC passes directly use the new pass
manager APIs.
Since `raw_string_ostream` doesn't own the string buffer, it is
desirable (in terms of memory safety) for users to directly reference
the string buffer rather than use `raw_string_ostream::str()`.
Work towards TODO comment to remove `raw_string_ostream::str()`.
This is a helper to avoid writing `getModule()->getDataLayout()`. I
regularly try to use this method only to remember it doesn't exist...
`getModule()->getDataLayout()` is also a common (the most common?)
reason why code has to include the Module.h header.
Uses the new InsertPosition class (added in #94226) to simplify some of
the IRBuilder interface, and removes the need to pass a BasicBlock
alongside a BasicBlock::iterator, using the fact that we can now get the
parent basic block from the iterator even if it points to the sentinel.
This patch removes the BasicBlock argument from each constructor or call
to setInsertPoint.
This has no functional effect, but later on as we look to remove the
`Instruction *InsertBefore` argument from instruction-creation
(discussed
[here](https://discourse.llvm.org/t/psa-instruction-constructors-changing-to-iterator-only-insertion/77845)),
this will simplify the process by allowing us to deprecate the
InsertPosition constructor directly and catch all the cases where we use
instructions rather than iterators.
This is a followup to #81014 and #84582: Before this patch, Clang
would accept `__attribute__((assume))` and `[[clang::assume]]` as
nonstandard spellings for the `[[omp::assume]]` attribute; this
resulted in a potentially very confusing name clash with C++23’s
`[[assume]]` attribute (and GCC’s `assume` attribute with the same
semantics).
This pr replaces every usage of `__attribute__((assume))` with
`[[omp::assume]]` and makes `__attribute__((assume))` and
`[[clang::assume]]` alternative spellings for C++23’s `[[assume]]`;
this shouldn’t cause any problems due to differences in appertainment
and because almost no-one was using this variant spelling to begin
with (a use in libclc has already been changed to use a different
attribute).
As part of the RemoveDIs project we need LLVM to insert instructions using
iterators wherever possible, so that the iterators can carry a bit of
debug-info. This commit implements some of that by updating the contents of
llvm/lib/Transforms/Utils to always use iterator-versions of instruction
constructors.
There are two general flavours of update:
* Almost all call-sites just call getIterator on an instruction
* Several make use of an existing iterator (scenarios where the code is
actually significant for debug-info)
The underlying logic is that any call to getFirstInsertionPt or similar
APIs that identify the start of a block need to have that iterator passed
directly to the insertion function, without being converted to a bare
Instruction pointer along the way.
Noteworthy changes:
* FindInsertedValue now takes an optional iterator rather than an
instruction pointer, as we need to always insert with iterators,
* I've added a few iterator-taking versions of some value-tracking and
DomTree methods -- they just unwrap the iterator. These are purely
convenience methods to avoid extra syntax in some passes.
* A few calls to getNextNode become std::next instead (to keep in the
theme of using iterators for positions),
* SeparateConstOffsetFromGEP has it's insertion-position field changed.
Noteworthy because it's not a purely localised spelling change.
All this should be NFC.
The deduplication of the calls to `omp_get_thread_limit` used to be
legal when originally added in
<e28936f613 (diff-de101c82aff66b2bda2d1f53fde3dde7b0d370f14f1ff37b7919ce38531230dfR123)>,
as the result (thread_limit) was immutable.
However, now that we have `thread_limit` clause, we no longer have
immutability; therefore `omp_get_thread_limit()` is not a deduplicable
runtime call.
Thus, removing `omp_get_thread_limit` from the
`DeduplicableRuntimeCallIDs` array.
Here's a simple example:
```
#include <omp.h>
#include <stdio.h>
int main()
{
#pragma omp target thread_limit(4)
{
printf("\n1:target thread_limit: %d\n", omp_get_thread_limit());
}
#pragma omp target thread_limit(3)
{
printf("\n2:target thread_limit: %d\n", omp_get_thread_limit());
}
return 0;
}
```
GCC-compiled binary execution: https://gcc.godbolt.org/z/Pjv3TWoTq
```
1:target thread_limit: 4
2:target thread_limit: 3
```
Clang/LLVM-compiled binary execution:
https://clang.godbolt.org/z/zdPbrdMPn
```
1:target thread_limit: 4
2:target thread_limit: 4
```
By my reading of the OpenMP spec GCC does the right thing here; cf.
<https://www.openmp.org/spec-html/5.2/openmpse12.html#x34-330002.4>:
> If a target construct with a thread_limit clause is encountered, the
thread-limit-var ICV from the data environment of the generated initial
task is instead set to an implementation defined value between one and
the value specified in the clause.
The common subexpression elimination (CSE) of the second call to
`omp_get_thread_limit` by LLVM does not seem to be correct, as it's not
an available expression at any program point(s) (in the scope of the
clause in question) after the second target construct with a
`thread_limit` clause is encountered.
Compiling with `-Rpass=openmp-opt -Rpass-analysis=openmp-opt
-Rpass-missed=openmp-opt` we have:
https://clang.godbolt.org/z/G7dfhP7jh
```
<source>:8:42: remark: OpenMP runtime call omp_get_thread_limit deduplicated. [OMP170] [-Rpass=openmp-opt]
8 | printf("\n1:target thread_limit: %d\n",omp_get_thread_limit());
| ^
```
OMP170 has the following explanation:
https://openmp.llvm.org/remarks/OMP170.html
> This optimization remark indicates that a call to an OpenMP runtime
call was replaced with the result of an existing one. This occurs when
the compiler knows that the result of a runtime call is immutable.
Removing duplicate calls is done by replacing all calls to that function
with the result of the first call. This cannot be done automatically by
the compiler because the implementations of the OpenMP runtime calls
live in a separate library the compiler cannot see.
This optimization will trigger for known OpenMP runtime calls whose
return value will not change.
At the same time I do not believe we have an analysis checking whether
this precondition holds here: "This occurs when the compiler knows that
the result of a runtime call is immutable."
AFAICT, such analysis doesn't appear to exist in the original patch
introducing deduplication, either:
-
9548b74a83
- https://reviews.llvm.org/D69930
The fix is to remove it from `DeduplicableRuntimeCallIDs`, effectively
reverting the addition in this commit (noting that `omp_get_max_threads`
is not present in `DeduplicableRuntimeCallIDs`, so it's possible this
addition was incorrect in the first place):
- [OpenMP][Opt] Annotate known runtime functions and deduplicate more,
-
e28936f613 (diff-de101c82aff66b2bda2d1f53fde3dde7b0d370f14f1ff37b7919ce38531230dfR123)
As a result, we're no longer unsoundly deduplicating the OpenMP runtime
call `omp_get_thread_limit` as illustrated by the test case: Note the
(correctly) repeated `call i32 @omp_get_thread_limit()`.
---------
Co-authored-by: Joseph Huber <huberjn@outlook.com>
Using the LoopInfo from OMPInfoCache after the Attributor ran resulted
in a crash due to it being in an invalid state.
---------
Co-authored-by: Ivan Radanov Ivanov <ivanov2@llnl.gov>
The specialisation will not be valid when ConstantInt gains native
support for vector types.
This is largely a mechanical change but with extra attention paid to constant
folding, InstCombineVectorOps.cpp, LoopFlatten.cpp and Verifier.cpp to
remove the need to call `getIntegerType()`.
Co-authored-by: Nikita Popov <github@npopov.com>
* Remove a call to CreatePointerBitCastOrAddrSpaceCast which merely adds
a no-op ptr-to-ptr bitcast.
* Most of the diff is from removing checks for no-op ptr-to-ptr bitcasts
in relevant LIT tests
Added support for LLVM IR code generation which is used for handling omp
target parallel code. The call for __kmpc_parallel_51 is generated and
the parallel region is outlined to separate function.
The proper setup of kmpc_target_init mode is not included in the commit.
It is assumed that the SPMD mode for target initialization is properly
set by other codegen functions.
Summary:
Part of the work done in the `libc` project is to provide host services
for things like `printf` or `malloc`, or generally any syscall-like
behaviour. This scheme works by emitting an externally visible global
called `__llvm_libc_rpc_client` that the host runtime can pick up to get
a handle to the global memory associated with the client. We use the
presence of this symbol to indicate whether or not we need to run an RPC
server. Normally, this symbol is only present if something requiring an
RPC server was linked in, such as `printf`. However, if this call to
`printf` was subsequently optimizated out, the symbol would remain and
cannot be removed (rightfully so) because of its linkage. This patch
adds a special-case optimization to remove this symbol so we can
indicate that an RPC server is no longer needed.
This patch puts this logic in `OpenMPOpt` as the most readily available
place for it. In the future, we should think how to move this somewhere
more generic. Furthermore, we use a hard-coded runtime name (which isn't
uncommon given all the other magic symbol names). But it might be nice
to abstract that part away.
We used to pass the min/max threads/teams values through different paths
from the frontend to the middle end. This simplifies the situation by
passing the values once, only when we will create the KernelEnvironment,
which contains the values. At that point we also manifest the metadata,
as appropriate. Some footguns have also been removed, e.g., our target
check is now triple-based, not calling convention-based, as the latter
is dependent on the ordering of operations. The types of the values have
been unified to int32_t.
This reverts commit ddbaa11e9f43a38d50d62a9b9b07c3653b6bf8ab.
Reapply the original commit, the broken test was repaired in 5e51363f38d083ab326736c0d4d1b5f9fe0de080 in the meantime.
The runtime needs to know about the acceptable launch bounds, especially
if the compiler (middle- or backend) assumed those bounds. While this
patch does not yet inform the runtime, it stores the bounds in a place
that can/will be accessed and is associated with the kernel.
If we update the state, or indicate a pessimistic fixpoint, we need to
consider NestedParallelism too.
Fixes part of https://github.com/llvm/llvm-project/issues/66708
That said, the reproducer still needs malloc which we don't support on
AMD GPU. Will be added later.
Barrier removal in OpenMPOpt normally removes barriers by proving that
they are redundant with barriers preceding them. However, it can't do
this with the "pseudo-barrier" at the end of kernels because that can't
be removed. Instead, it removes the barriers preceding the end of the
kernel which that end-of-kernel barrier is redundant with. However,
these barriers aren't always redundant with the end-of-kernel barrier
when loops are involved, and removing them can lead to incorrect results
in compiled code.
This change fixes this by requiring that these pre-end-of-kernel
barriers also have the kernel end as a unique successor before removing
them. It also changes the initialization of `ExitED` for kernels since
the kernel end is not an aligned barrier.
Current OpenMPOpt assumes all kernels are OpenMP kernels (aka. with
"kernel"
attribute). This doesn't hold if we mix OpenMP code and CUDA code by
lingking
them together because CUDA kernels are not annotated with the attribute.
This
patch removes the assumption and added a new counter for those
non-OpenMP
kernels.
Fix#66687.
The associated function can be a nullptr if it is an indirect call.
This causes a crash in `CheckCallee` which always assumes the callee
is a valid pointer.
Fix#66904.
The Attributor has gained support for indirect calls but it is opt-in.
This patch makes AAKernelInfoCallSite able to handle multiple potential
callees.
Before, we checked the parallel region only once, and ignored updates in
the KernelInfo for the parallel region that happened later. This caused
us to think nested parallel sections are not present even if they are,
among other things.
When we remove barriers, we might need to remove llvm.assume
assumptions as well. However, doing this early, thus in the module pass,
will cause us to miss out on information we might need. There are few
situations we can eliminate barriers across functions, for now we simply
disable elimination of barriers that require assumptions to be removed
during the early module pass.
AAIndirectCallInfo will collect information and specialize indirect call
sites. It is similar to our IndirectCallPromotion but runs as part of
the Attributor (so with assumed callee information). It also expands
more calls and let's the rest of the pipeline figure out what is UB, for
now. We use existing call promotion logic to improve the result,
otherwise we rely on the (implicit) function pointer cast.
This effectively "fixes" #60327 as it will undo the type punning early
enough for the inliner to work with the (now specialized, thus direct)
call.
Fixes: https://github.com/llvm/llvm-project/issues/60327
Clang does not create a wrapper function for SPMD kernels. If it does
not, we still want to collect the parallel region, even if we have no
use for it right now.
When other AAs query the current value of KernelEnvC via the callback
KernelConfigurationSimplifyCB we need to ensure they are now dependent
on the AAKernelInfo that is in charge of the KernelEnvC.
Since we no longer support typed LLVM IR pointer types, the code can
be simplified into for example using PointerType::get directly instead
of using Type::getInt8PtrTy and Type::getInt32PtrTy etc.
Differential Revision: https://reviews.llvm.org/D156733
This patch introduces per kernel environment. Previously, flags such as execution mode are set through global variables with name like `__kernel_name_exec_mode`. They are accessible on the host by reading the corresponding global variable, but not from the device. Besides, some assumptions, such as no nested parallelism, are not per kernel basis, preventing us applying per kernel optimization in the device runtime.
This is a combination and refinement of patch series D116908, D116909, and D116910.
Depend on D155886.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D142569
This patch introduces per kernel environment. Previously, flags such as execution mode are set through global variables with name like `__kernel_name_exec_mode`. They are accessible on the host by reading the corresponding global variable, but not from the device. Besides, some assumptions, such as no nested parallelism, are not per kernel basis, preventing us applying per kernel optimization in the device runtime.
This is a combination and refinement of patch series D116908, D116909, and D116910.
Depend on D155886.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D142569
AANonNull is now the first AA that is always queried via the new APIs
and not created manually. Others will follow shortly to avoid trivial
AAs whenever possible.
This commit introduced some helper logic that will make it simpler to
port the next one. It also untangles AADereferenceable and AANonNull
such that the former does not keep a handle on the latter. Finally,
we stop deducing `nonnull` for `undef`, which was incorrect.
A kernel can be exited in a non-aligned fashion, so we cannot pretend it
always ends in an aligned barrier. Instead, we require an explicit
aligned barrier as we lack a divergence analysis at this point.
