Currently clang does not emit device template variables
instantiated only in host functions, however, nvcc is
able to do that:
https://godbolt.org/z/fneEfferY
This patch fixes this issue by refactoring and extending
the existing mechanism for emitting static device
var ODR-used by host only. Basically clang records
device variables ODR-used by host code and force
them to be emitted in device compilation. The existing
mechanism makes sure these device variables ODR-used
by host code are added to llvm.compiler-used, therefore
they are guaranteed not to be deleted.
It also fixes non-ODR-use of static device variable by host code
causing static device variable to be emitted and registered,
which should not.
Reviewed by: Artem Belevich
Differential Revision: https://reviews.llvm.org/D102237
Add device variables to llvm.compiler.used if they are
ODR-used by either host or device functions.
This is necessary to prevent them from being
eliminated by whole-program optimization
where the compiler has no way to know a device
variable is used by some host code.
Reviewed by: Artem Belevich
Differential Revision: https://reviews.llvm.org/D98814
The internalization pass only internalizes global variables
with no users. If the global variable has some dead user,
the internalization pass will not internalize it.
To be able to internalize global variables with dead
users, a global dce pass is needed before the
internalization pass.
This patch adds that.
Reviewed by: Artem Belevich, Matt Arsenault
Differential Revision: https://reviews.llvm.org/D98783
Recently atomicrmw started to support fadd/fsub:
https://reviews.llvm.org/D53965
However clang atomic builtins fetch add/sub still does not support
emitting atomicrmw fadd/fsub.
This patch adds that.
Reviewed by: John McCall, Artem Belevich, Matt Arsenault, JF Bastien,
James Y Knight, Louis Dionne, Olivier Giroux
Differential Revision: https://reviews.llvm.org/D71726
Clang test CodeGenCUDA/kernel-stub-name.cu uses never defined DKERN
variable in a CHECK-NOT directive. This commit replace the variable by a
regex, thereby avoiding the issue.
Reviewed By: yaxunl
Differential Revision: https://reviews.llvm.org/D99832
Commit 8129521318 changed a line defining
PREFIX in clang test CodeGenCUDA/device-stub.cu into a CHECK-NOT
directive. All following lines using PREFIX are therefore using an
undefined variable since the pattern defining PREFIX is not supposed to
occur and CHECK-NOT are checked independently.
This commit replaces all uses of PREFIX by the regex used to define it,
thereby avoiding the problem.
Reviewed By: yaxunl
Differential Revision: https://reviews.llvm.org/D99831
Add builtin function __builtin_get_device_side_mangled_name
to get device side manged name for functions and global
variables, which can be used to get symbol address of kernels
or variables by mangled name in dynamically loaded
bundled code objects at run time.
Reviewed by: Artem Belevich
Differential Revision: https://reviews.llvm.org/D99301
Currently clang uses stub function to launch kernel. This is inconvenient
to interop with C++ programs since the stub function has different name
as kernel, which is required by ROCm debugger.
This patch emits a variable symbol which has the same name as the kernel
and uses it to register and launch the kernel. This allows C++ program to
launch a kernel by using the original kernel name.
Reviewed by: Artem Belevich
Differential Revision: https://reviews.llvm.org/D86376
An global value in the `llvm.used` list does not have GC root semantics on ELF targets.
This will be changed in a subsequent backend patch.
Change some `llvm.used` in the ELF code path to use `llvm.compiler.used` to
prevent undesired GC root semantics.
Change one extern "C" alias (due to `__attribute__((used))` in extern "C") to use `llvm.compiler.used` on all targets.
GNU ld has a rule "`__start_/__stop_` references from a live input section retain the associated C identifier name sections",
which LLD may drop entirely (currently refined to exclude SHF_LINK_ORDER/SHF_GROUP) in a future release (the rule makes it clumsy to GC metadata sections; D96914 added a way to try the potential future behavior).
For `llvm.used` global values defined in a C identifier name section, keep using `llvm.used` so that
the future LLD change will not affect them.
rnk kindly categorized the changes:
```
ObjC/blocks: this wants GC root semantics, since ObjC mainly runs on Mac.
MS C++ ABI stuff: wants GC root semantics, no change
OpenMP: unsure, but GC root semantics probably don't hurt
CodeGenModule: affected in this patch to *not* use GC root semantics so that __attribute__((used)) behavior remains the same on ELF, plus two other minor use cases that don't want GC semantics
Coverage: Probably want GC root semantics
CGExpr.cpp: refers to LTO, wants GC root
CGDeclCXX.cpp: one is MS ABI specific, so yes GC root, one is some other C++ init functionality, which should form GC roots (C++ initializers can have side effects and must run)
CGDecl.cpp: Changed in this patch for __attribute__((used))
```
Differential Revision: https://reviews.llvm.org/D97446
For -fgpu-rdc mode, static device vars in different TU's may have the same name.
To support accessing file-scope static device variables in host code, we need to give them
a distinct name and external linkage. This can be done by postfixing each static device variable with
a distinct CUID (Compilation Unit ID) hash.
Since the static device variables have different name across compilation units, now we let
them have external linkage so that they can be looked up by the runtime.
Reviewed by: Artem Belevich, and Jon Chesterfield
Differential Revision: https://reviews.llvm.org/D85223
Currently managed variables are emitted as undefined symbols, which
causes difficulty for diagnosing undefined symbols for non-managed
variables.
This patch transforms managed variables in device compilation so that
they can be emitted as normal variables.
Reviewed by: Artem Belevich
Differential Revision: https://reviews.llvm.org/D96195
For -fgpu-rdc, shadow variables should not be internalized, otherwise
they cannot be accessed by other TUs. This is necessary because
the shadow variable of external device variables are always
emitted as undefined symbols, which need to resolve to a global
symbols.
Managed variables need to be emitted as undefined symbols
in device compilations.
Reviewed by: Artem Belevich
Differential Revision: https://reviews.llvm.org/D95901
- The failures are all cc1-based tests due to the missing `-aux-triple` options,
which is always prepared by the driver in CUDA/HIP compilation.
- Add extra check on the missing aux-targetinfo to prevent crashing.
[hip][cuda] Enable extended lambda support on Windows.
- On Windows, extended lambda has extra issues due to the numbering
schemes are different between the host compilation (Microsoft C++ ABI)
and the device compilation (Itanium C++ ABI. Additional device side
lambda number is required per lambda for the host compilation to
correctly mangle the device-side lambda name.
- A hybrid numbering context `MSHIPNumberingContext` is introduced to
number a lambda for both host- and device-compilations.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D69322
This reverts commit 4874ff0241.
- On Windows, extended lambda has extra issues due to the numbering
schemes are different between the host compilation (Microsoft C++ ABI)
and the device compilation (Itanium C++ ABI. Additional device side
lambda number is required per lambda for the host compilation to
correctly mangle the device-side lambda name.
- A hybrid numbering context `MSHIPNumberingContext` is introduced to
number a lambda for both host- and device-compilations.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D69322
This patch implements codegen for __managed__ variable attribute for HIP.
Diagnostics will be added later.
Differential Revision: https://reviews.llvm.org/D94814
Defaulted destructor was treated inconsistently, compared to other
compiler-generated functions.
When Sema::IdentifyCUDATarget() got called on just-created dtor which didn't
have implicit __host__ __device__ attributes applied yet, it would treat it as a
host function. That happened to (sometimes) hide the error when dtor referred
to a host-only functions.
Even when we had identified defaulted dtor as a HD function, we still treated it
inconsistently during selection of usual deallocators, where we did not allow
referring to wrong-side functions, while it is allowed for other HD functions.
This change brings handling of defaulted dtors in line with other HD functions.
Differential Revision: https://reviews.llvm.org/D94732
This patch removes the -f[no-]trapping-math flags from the -cc1 command line. These flags are ignored in the command line parser and their semantics is fully handled by -ffp-exception-mode.
This patch does not remove -f[no-]trapping-math from the driver command line. The driver flags are being used and do affect compilation.
Reviewed By: dexonsmith, SjoerdMeijer
Differential Revision: https://reviews.llvm.org/D93395
ELF -cc1 -mrelocation-model pic will default to no semantic interposition plus
setting dso_local on default visibility external linkage definitions, so that
COFF, Mach-O and ELF output will be similar.
This patch makes tests immune to the differences.
For a default visibility external linkage definition, dso_local is set for ELF
-fno-pic/-fpie and COFF and Mach-O. Since default clang -cc1 for ELF is similar
to -fpic ("PIC Level" is not set), this nuance causes unneeded binary format differences.
To make emitted IR similar, ELF -cc1 -fpic will default to -fno-semantic-interposition,
which sets dso_local for default visibility external linkage definitions.
To make this flip smooth and enable future (dso_local as definition default),
this patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `.
This patch diagnoses invalid references of global host variables in device,
global, or host device functions.
Differential Revision: https://reviews.llvm.org/D91281
In C++ when a reference variable is captured by copy, the lambda
is supposed to make a copy of the referenced variable in the captures
and refer to the copy in the lambda. Therefore, it is valid to capture
a reference to a host global variable in a device lambda since the
device lambda will refer to the copy of the host global variable instead
of access the host global variable directly.
However, clang tries to avoid capturing of reference to a host global variable
if it determines the use of the reference variable in the lambda function is
not odr-use. Clang also tries to emit load of the reference to a global variable
as load of the global variable if it determines that the reference variable is
a compile-time constant.
For a device lambda to capture a reference variable to host global variable
and use the captured value, clang needs to be taught that in such cases the use of the reference
variable is odr-use and the reference variable is not compile-time constant.
This patch fixes that.
Differential Revision: https://reviews.llvm.org/D91088
Recently HIP toolchain made a change to use clang instead of opt/llc to do compilation
(https://reviews.llvm.org/D81861). The intention is to make HIP toolchain canonical like
other toolchains.
However, this change introduced an unintentional change regarding backend fp fuse
option, which caused regressions in some HIP applications.
Basically before the change, HIP toolchain used clang to generate bitcode, then use
opt/llc to optimize bitcode and generate ISA. As such, the amdgpu backend takes
the default fp fuse mode which is 'Standard'. This mode respect contract flag of
fmul/fadd instructions and do not fuse fmul/fadd instructions without contract flag.
However, after the change, HIP toolchain now use clang to generate IR, do optimization,
and generate ISA as one process. Now amdgpu backend fp fuse option is determined
by -ffp-contract option, which is 'fast' by default. And this -ffp-contract=fast language option
is translated to 'Fast' fp fuse option in backend. Suddenly backend starts to fuse fmul/fadd
instructions without contract flag.
This causes wrong result for some device library functions, e.g. tan(-1e20), which should
return 0.8446, now returns -0.933. What is worse is that since backend with 'Fast' fp fuse
option does not respect contract flag, there is no way to use #pragma clang fp contract
directive to enforce fp contract requirements.
This patch fixes the regression by introducing a new value 'fast-honor-pragmas' for -ffp-contract
and use it for HIP by default. 'fast-honor-pragmas' is equivalent to 'fast' in frontend but
let the backend to use 'Standard' fp fuse option. 'fast-honor-pragmas' is useful since 'Fast'
fp fuse option in backend does not honor contract flag, it is of little use to HIP
applications since all code with #pragma STDC FP_CONTRACT or any IR from a
source compiled with -ffp-contract=on is broken.
Differential Revision: https://reviews.llvm.org/D90174
Add an option -munsafe-fp-atomics for AMDGPU target.
When enabled, clang adds function attribute "amdgpu-unsafe-fp-atomics"
to any functions for amdgpu target. This allows amdgpu backend to use
unsafe fp atomic instructions in these functions.
Differential Revision: https://reviews.llvm.org/D91546
arguments.
* Adds 'nonnull' and 'dereferenceable(N)' to 'this' pointer arguments
* Gates 'nonnull' on -f(no-)delete-null-pointer-checks
* Introduces this-nonnull.cpp and microsoft-abi-this-nullable.cpp tests to
explicitly test the behavior of this change
* Refactors hundreds of over-constrained clang tests to permit these
attributes, where needed
* Updates Clang12 patch notes mentioning this change
Reviewed-by: rsmith, jdoerfert
Differential Revision: https://reviews.llvm.org/D17993
- In certain cases, a generic pointer could be assumed as a pointer to
the global memory space or other spaces. With a dedicated target hook
to query that address space from a given value, infer-address-space
pass could infer and propagate that to all its users.
Differential Revision: https://reviews.llvm.org/D91121
- If an aggregate argument is indirectly accessed within kernels, direct
passing results in unpromotable `alloca`, which degrade performance
significantly. InferAddrSpace pass is enhanced in
[D91121](https://reviews.llvm.org/D91121) to take the assumption that
generic pointers loaded from the constant memory could be regarded
global ones. The need for the coercion on aggregate arguments is
mitigated.
Differential Revision: https://reviews.llvm.org/D89980
Currently for explicit template function instantiation in CUDA/HIP device
compilation clang emits instantiated kernel with external linkage
and instantiated device function with internal linkage.
This is fine for -fno-gpu-rdc since there is only one TU.
However this causes duplicate symbols for kernels for -fgpu-rdc if
the same instantiation happen in multiple TU. Or missing symbols
if a device function calls an explicitly instantiated template function
in a different TU.
To make explicit template function instantiation work for
-fgpu-rdc we need to follow the C++ linkage paradigm, i.e.
use weak_odr linkage.
Differential Revision: https://reviews.llvm.org/D90311
D17779: host-side shadow variables of external declarations of device-side
global variables have internal linkage and are referenced by
`__cuda_register_globals`.
nvcc from CUDA 11 does not allow `__device__ inline` or `__device__ constexpr`
(C++17 inline variables) but clang has incorrectly supported them for a while:
```
error: A __device__ variable cannot be marked constexpr
error: An inline __device__/__constant__/__managed__ variable must have internal linkage when the program is compiled in whole program mode (-rdc=false)
```
If such a variable (which has a comdat group) is discarded (a copy from another
translation unit is prevailing and selected), accessing the variable from
outside the section group (`__cuda_register_globals`) is a violation of the ELF
specification and will be rejected by linkers:
> A symbol table entry with STB_LOCAL binding that is defined relative to one of a group's sections, and that is contained in a symbol table section that is not part of the group, must be discarded if the group members are discarded. References to this symbol table entry from outside the group are not allowed.
As a workaround, don't register such inline variables for now.
(If we register the variables in all TUs, we will keep multiple instances of the shadow and break the C++ semantics for inline variables).
We should reject such variables in Sema but our internal users need some time to migrate.
Reviewed By: tra
Differential Revision: https://reviews.llvm.org/D88786
To facilitate faster loading of device binaries and share them among processes,
HIP runtime favors their alignment being 4096 bytes. HIP runtime can load
unaligned device binaries, however, aligning them at 4096 bytes results in
faster loading and less shared memory usage.
This patch adds an option -bundle-align to clang-offload-bundler which allows
bundles to be aligned at specified alignment. By default it is 1, which is NFC
compared to existing format.
This patch then aligns embedded fat binary and device binary inside fat binary
at 4096 bytes.
It has been verified this change does not cause significant overall file size increase
for typical HIP applications (less than 1%).
Differential Revision: https://reviews.llvm.org/D88734
A static device variable may be accessed in host code through
cudaMemCpyFromSymbol etc. Currently clang does not
emit the static device variable if it is only referenced by
host code, which causes host code to fail at run time.
This patch fixes that.
Differential Revision: https://reviews.llvm.org/D88115
- After loading builtin bitcode for linking, skip adding default
function attributes on LLVM intrinsics as their attributes are
well-defined and retrieved directly from internal definitions. Adding
extra attributes on intrinsics results in inconsistent result when
`-save-temps` is present. Also, that makes few optimizations
conservative.
Differential Revision: https://reviews.llvm.org/D87761
Temporarily revert commit 04abbb3a78
due to regressions in some HIP apps due backend issues revealed by
this change.
Will re-commit it when backend issues are fixed.
- Skip generating profile data on `__global__` function in the host
compilation. It's a host-side stub function only and don't have
profile instrumentation generated on the real function body. The extra
profile data results in the malformed instrumentation profile data.
- Skip generating region mapping on functions in the wrong-side, i.e.,
+ For the device compilation, skip host-only functions; and,
+ For the host compilation, skip device-only functions (including
`__global__` functions.)
- As the device-side profiling is not ready yet, only host-side profile
code generation is checked.
Differential Revision: https://reviews.llvm.org/D85276
Steffen Larsen