Hello,
I like this idea. I have a couple thoughts to add.
On 05/05/2025 09:46, Yangyu Chen wrote:
On 5 May 2025, at 16:34, Kyrylo Tkachov <ktkac...@nvidia.com> wrote:
On 4 May 2025, at 19:19, Yangyu Chen <c...@cyyself.name> wrote:
Hi everyone,
This patch series introduces support for the target_clones profile
option in GCC. This option enables users to specify target_clones
attributes in a separate file, allowing GCC to generate multiple
versions of the function with different ISA extensions based on the
specified profile. This is achieved using the -ftarget-profile
option.
Interesting idea, but the terminology is confusing as is.
In GCC “profile” usually refers to an execution profile gathered through PGO
instrumentation or perf.
Whereas here I think you use “profile” to mean a “RISC-V profile” which is
something like a set of target architecture extensions?
Thanks,
Kyrill
Sorry for the unclear information. The target profile here refers
to the target_clones attribute for each function. You can find an
example in the second patch.
I was also confused by the naming initially. Maybe something like
"-ffunction-clone-table" instead?
For instance, we want a function foo to generate default and RISC-V
vector targets, while a function bar should generate default and
zba,zbb targets. The corresponding source code could be as follows:
```
__attribute__((target_clones("default","arch=+v")))
void foo();
__attribute__((target_clones("default","arch=+zba,+zbb")))
void bar();
```
But if we have a target profile, we can describe it as follows in
a separate file:
```
foo:default#arch=+v
bar:default#arch=+zba,+zbb
```
As every function needs the default version it might be nice to make
that implicit. We can then avoid representing and subsequently
diagnosing invalid files. This could then be:
```
foo:arch=+v
bar:arch=+zba,+zbb#+v
```
Additionally, I think ideally the file can express functions
disambiguated by file, signature, and namespace.
I imagine we could use similar syntax to gdb supports?
For example:
```
foo |arch=+v
bar(int, char) |arch=+zba,+zbb
file.C:baz(char) |arch=+zba,+zbb#arch=+v
namespace::qux |arch=+v
```
Thanks,
Alfie Richards
Thanks,
Yangyu Chen
The primary objective of this patch series is to provide a
user-friendly way to specify target_clones attributes without
modifying the source code. This approach enhances the source code's
cleanliness, facilitates easier maintenance, and ensures portability
across different architectures and compiler versions.
The example usage of the target_clones profile option is detailed in
the commit message of the second patch.
I understand that this patch lacks comprehensive documentation and
test cases, as I am still in the process of writing them.
However, I would appreciate feedback on the implementation before
adding them. If the implementation is deemed acceptable, I
will proceed with writing the documentation and test cases.
Yangyu Chen (2):
Fortran: Do not make_decl_rtl in trans_function_start
Add target_clones profile option support
gcc/common.opt | 7 +++++++
gcc/fortran/trans-decl.cc | 3 ---
gcc/multiple_target.cc | 24 +++++++++++++++++++++++-
gcc/opts.cc | 23 +++++++++++++++++++++++
4 files changed, 53 insertions(+), 4 deletions(-)
--
2.49.0
