Summary:
Previous patches have made the `rpc.h` header independent of the `libc`
internals. This allows us to include it directly rather than providing
an indirect C API. This patch only does the work to move the header. A
future patch will pull out the `rpc_server` interface and simply replace
it with a single function that handles the opcodes.
Summary:
These functions were deprecated in ROCR 1.3 which was released quite
some time ago. The main functionality that was lost was modifying and
inspecting the code object indepedently of the executable, however we do
all of that custom through our ELF API. This should be within the
versions of other functions we use.
Summary:
Currently, the RPC interface uses a basic opcode to communicate with the
server. This currently is 16 bits. There's no reason for this to be 16
bits, because on the GPU a 32-bit write is the same as a 16-bit write
performance wise.
Additionally, I am now making all the `libc` based opcodes qualified
with the 'c' type, mimiciing how Linux handles `ioctls` all coming from
the same driver. This will make it easier to extend the interface when
it's exported directly.
We are finalizing the header inclusion policy, and for our public
headers in the `libc/include` folder, they must use relative path in
`"..."` when including each other.
This PR does the cleanup making sure that all the public header
inclusions in `libc/include` folder use relative paths.
---------
Co-authored-by: Nick Desaulniers <nickdesaulniers@users.noreply.github.com>
Summary:
I'm going to attempt to move the `rpc.h` header to a separate folder
that we can install and include outside of `libc`. Before doing this I'm
going to try to trim up the file so there's not as many things I need to
copy to make it work. This dependency on `cpp::functional` is a low
hanging fruit. I only did it so that I could overload the argument of
the work function so that passing the id was optional in the lambda,
that's not a *huge* deal and it makes it more explicit I suppose.
Summary:
Make a separate thread to run the server when we launch. This is
required by CUDA, which you can force with `export
CUDA_LAUNCH_BLOCKING=1`. I figured I might as well be consistent and do
it for the AMD implementation as well even though I believe it's not
necessary.
Summary:
It's safer to use the maximum size, as this prevents the runtime from
oversubscribing with multiple producers. Additionally we should set the
barrier bit to ensure that the queue entries block if multiple are
submitted (Which shouldn't happen for this tool).
Summary:
This function can easily be implemented by forwarding it to the host
process. This shows up in a few places that we might want to test the
GPU so it should be provided. Also, I find the idea of the GPU
offloading work to the CPU via `system` very funny.
The RPC server directly includes the printf code, but doesn't support
errno, so the %m conversion needs to be disabled there as well. This
patch does that.
Summary:
The loader is used as a test utility to run traditionally CPU based unit
tests on the GPU. This has issues when used with something like
`llvm-lit` because the GPU runtimes have a nasty habit of either running
out of resources or hanging when they are overloaded. To combat this, I
added this option to force each process to perform the GPU part
serially.
This is done right now with a simple file lock on the executing file. I
was originally thinking about using more complex IPC to allow N
processes to share execution, but that seemed overly complicated given
the incredibly large number of failure modes it introduces. File locks
are nice here because if the process crashes or is killed it will
release the lock automatically (at least on Linux). This is in contrast
to something like POSIX shared memory which will stick around until it's
unlinked, meaning that if someone did `sigkill` on the program it would
never get cleaned up and other threads might wait on a mutex that never
occurs.
Restricting this to one thread isn't overly ideal, given the fact that
the runtime can likely handle at least a *few* separate processes, but
this was easy and it works, so might as well start here. This will
hopefully unblock me on running `libcxx` tests, as those ran with so
much parallelism spurious failures were very common.
Summary:
This patch removes the ad-hoc parsing that I used previously and
replaces it with the LLVM CommnadLine interface. This doesn't change any
functionality, but makes it easier to maintain.
Summary:
We get the `strlen` to know how much memory to allocate here, but it
wasn't taking into account if the padding was larger than the string
itself. This patch sets it to an empty string so we always add the
minimum size. This implementation is slightly wasteful with memory, but
I am not concerned with a few extra bytes here and there for some memory
that gets immediately free'd.
Summary:
This patch implements the `printf` family of functions on the GPU using
the new variadic support. This patch adapts the old handling in the
`rpc_fprintf` placeholder, but adds an extra RPC call to get the size of
the buffer to copy. This prevents the GPU from needing to parse the
string. While it's theoretically possible for the pass to know the size
of the struct, it's prohibitively difficult to do while maintaining ABI
compatibility with NVIDIA's varargs.
Depends on https://github.com/llvm/llvm-project/pull/96015.
Summary:
Straightforward RPC implementation of the `remove` function for the GPU.
Copies over the string and calls `remove` on it, passing the result
back. This is required for building some `libc++` functionality.
Summary:
Currently we just print the error as seen, this makes it difficult if
something goes wrong to know where it failed. This patch just adds in
line numbers to all the error handling routines so you can trace it
back.
Summary:
This patch adds a temporary implementation that uses a struct-based
interface in lieu of varargs support. Once varargs support exists we
will move this implementation to the "real" printf implementation.
Conceptually, this patch has the client copy over its format string and
arguments to the server. The server will then scan the format string
searching for any specifiers that are actually a string. If it is a
string then we will send the pointer back to the server to tell it to
copy it back. This copied value will then replace the pointer when the
final formatting is done.
This will require a built-in extension to the varargs support to get
access to the underlying struct. The varargs used on the GPU will simply
be a struct wrapped in a varargs ABI.
Summary:
The current implementation of RPC tied everything to device IDs and
forced us to do init / shutdown to manage some global state. This turned
out to be a bad idea in situations where we want to track multiple
hetergeneous devices that may report the same device ID in the same
process.
This patch changes the interface to instead create an opaque handle to
the internal device and simply allocates it via `new`. The user will
then take this device and store it to interface with the attached
device. This interface puts the burden of tracking the device identifier
to mapped d evices onto the user, but in return heavily simplifies the
implementation.
Fixes#86546 and removes the macro `LIBC_HAS_BUILTIN`. This was
necessary to support older compilers that did not support
`__has_builtin`. All of the compilers we support already have this
builtin.
See: https://libc.llvm.org/compiler_support.html
All uses now use `__has_builtin` directly
cc @nickdesaulniers
This patch updates the construction of packet headers to replace the
usage of ACQUIRE/RELEASE with SCACQUIRE/SCRELEASE which is now
recommended.
The patch also ensures consistency across kernel dispatches.
Summary:
The libc build has a few utilties that need to be built before we can do
everything in the full build. The one requirement currently is the
`libc-hdrgen` binary. If we are doing a full build runtimes mode we
first add `libc` to the projects list and then only use the `projects`
portion to buld the `libc` portion. We also use utilities for the GPU
build, namely the loader utilities. Previously we would build these
tools on-demand inside of the cross-build, which tool some hacky
workarounds for the dependency finding and target triple. This patch
instead just builds them similarly to libc-hdrgen and then passses them
in. We now either pass it manually it it was built, or just look it up
like we do with the other `clang` tools.
Depends on https://github.com/llvm/llvm-project/pull/84664
Summary:
We previously changed the data layout for the RPC buffer to make it lane
size agnostic. I put off changing the size for the server case to make
the patch smaller. This patch simply reorganizes code by making the lane
size an argument to the port rather than a templtae size. Heavily
simplifies a lot of code, no more `std::variant`.
Summary:
These values were incorrectly flipped, setting the size of the blocks to
the threads and vice-versa. When I originally wrote the thread utilities
it was using COV4 which used an implicit format. Then when I updated I
accidentally flipped them and never noticed because nothing depended on
the size of the threads until I checked it manually.
Summary:
Recent changes added an include path in the float128 type that used the
internal `libc` path to find the macro. This doesn't work once it's
installed because we need to search from the root of the install dir.
This patch adds "include/" to the include path so that our inclusion
of installed headers always match the internal use.
Summary:
This directory is leftover from when we handled both AMDGPU and NVPTX in
the same build and merged them into a pseudo triple. Now the only thing
it contains is the RPC server header. This gets rid of it, but now that
it's in the base install directory we should make it clear that it's an
LLVM libc header.
Summary:
This is a massive patch because it reworks the entire build and
everything that depends on it. This is not split up because various bots
would fail otherwise. I will attempt to describe the necessary changes
here.
This patch completely reworks how the GPU build is built and targeted.
Previously, we used a standard runtimes build and handled both NVPTX and
AMDGPU in a single build via multi-targeting. This added a lot of
divergence in the build system and prevented us from doing various
things like building for the CPU / GPU at the same time, or exporting
the startup libraries or running tests without a full rebuild.
The new appraoch is to handle the GPU builds as strict cross-compiling
runtimes. The first step required
https://github.com/llvm/llvm-project/pull/81557 to allow the `LIBC`
target to build for the GPU without touching the other targets. This
means that the GPU uses all the same handling as the other builds in
`libc`.
The new expected way to build the GPU libc is with
`LLVM_LIBC_RUNTIME_TARGETS=amdgcn-amd-amdhsa;nvptx64-nvidia-cuda`.
The second step was reworking how we generated the embedded GPU library
by moving it into the library install step. Where we previously had one
`libcgpu.a` we now have `libcgpu-amdgpu.a` and `libcgpu-nvptx.a`. This
patch includes the necessary clang / OpenMP changes to make that not
break the bots when this lands.
We unfortunately still require that the NVPTX target has an `internal`
target for tests. This is because the NVPTX target needs to do LTO for
the provided version (The offloading toolchain can handle it) but cannot
use it for the native toolchain which is used for making tests.
This approach is vastly superior in every way, allowing us to treat the
GPU as a standard cross-compiling target. We can now install the GPU
utilities to do things like use the offload tests and other fun things.
Some certain utilities need to be built with
`--target=${LLVM_HOST_TRIPLE}` as well. I think this is a fine
workaround as we
will always assume that the GPU `libc` is a cross-build with a
functioning host.
Depends on https://github.com/llvm/llvm-project/pull/81557
Summary:
The RPC interface needs to handle an entire warp or wavefront at once.
This is currently done by using a compile time constant indicating the
size of the buffer, which right now defaults to some value on the client
(GPU) side. However, there are currently attempts to move the `libc`
library to a single IR build. This is problematic as the size of the
wave fronts changes between ISAs on AMDGPU. The builitin
`__builtin_amdgcn_wavefrontsize()` will return the appropriate value,
but it is only known at runtime now.
In order to support this, this patch restructures the packet. Now
instead of having an array of arrays, we simply have a large array of
buffers and slice it according to the runtime value if we don't know it
ahead of time. This also somewhat has the advantage of making the buffer
contiguous within a page now that the header has been moved out of it.
Summary:
The RPC interface uses several ports to provide parallel access. Right
now we begin the search at the beginning, which heavily contests the
early ports. Using the SMID allows us to stagger the starting index
based off of the cluster identifier that is executing the current warp.
Multiple warps can share an SM, but it will guaruntee that the
contention for the low indices is lower.
This also increases the maximum port size to around 4096, this is
because 512 isn't enough to cover the full hardare parallelism needed to
guarantee this doesdn't deadlock.
Prior to this change, we wouldn't build headers that aren't referenced
by other parts of the libc which would result in a build error during
installation. To address this, we make the header target a dependency of
the libc archive. Additionally, we also redo the install targets, moving
the install targets closer to build targets and simplifying the
hierarchy and generally matching what we do for other runtimes.
Summary:
This pointer has been causing issues. Allocating and reading from coarse
memory on the CPU is not guaranteed and varies depending on the kernel
version and support. Previously we attempted to pin the memory but this
caused unexpected failures. This should be a legal operation and work
around the problem as fine-grained memory should be always legal to
write to by both sides.
Summary:
This caused the bots to begin failing. Revert for now to get the bot
green.
This reverts commit 8bea804923a1b028e86b177caccb3258708ca01c.
This reverts commit e1395c7bdbe74b632ba7fbd90e2be2b4d82ee09e.
Summary:
This may be problematic to pin a stack pointer. Allocate it via the OS
allocator instead as the documentation suggests.
For some reason, if you attempt to free this pointer after the memory
region has been unlocked, it will return an invalid pointer.
