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Add RISC-V Profiles format #36
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Add RISC-V Profiles format. Signed-off-by: Jiawei <jiawei@iscas.ac.cn>
README.mkd
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### Profile-based format | ||
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Profiles should be recognized and used in the `-march=` option. | ||
The benefit is that it is easy for toolchain parsing the profiles string and expanding it into normal extensions combinations. It’s also easy to combine a profile with any extensions. |
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I'm not sure this is the right place to be advocating for why profiles make sense.
Regarding "It's also easy to combine a profile with any extensions" - this patch should give an example of that.
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Fixed in new version, remove this descriptions, give an example behind.
README.mkd
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If the 'C' (compressed) instruction set extension is targeted, the compiler | ||
will generate compressed instructions where possible. |
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Those two lines should move before ### Profile-based format
?
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Thanks for your metion, moved~
README.mkd
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which include all the mandatory extensions required by this profile. | ||
Here we are `not dealing with optional extensions` to profiles in the toolchain. | ||
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Moreover, some extensions are still not ratified yet. So the toolchain only keeps their name strings only. |
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I would prefer drop that, RVA22 ratified, and means those ext. defined in RVA22 also ratified.
[1] https://github.com/riscv/riscv-profiles/releases/tag/v1.0
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Droped these two lines.
Update profiles format descriptions, follow all comments in discuss. Thanks Alex Bradbury and Kito Cheng's review. Signed-off-by: Jiawei <jiawei@iscas.ac.cn>
README.mkd
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`-march` option is easy for toolchain parsing the profiles string and expanding | ||
it into normal extensions combinations. | ||
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Profiles format has the following form `-march=<profile-name>[+<option-ext>]+`. |
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I would suggest define that in BNF.
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Updated, thanks for the suggestions.
This got briefly brought up during the SIG toolchain meeting today, but got rapidly derailed into a process discussion. Since the root point seems important, I am repeating it here. In addition to defining the syntax for the -march string for profiles, there is a separate set of task items required to define and implement support for each of the new extensions which were defined in the ratified profile document. From the perspective of LLVM, my current intent is to make the support for all the various extensions a blocker for merging the -march profile parsing support. This may evolve, and I'm open to the arguments on why we should adopt a different posture, but that argument will need to be explicitly made. |
You are right, Christoph added a comment here riscv-admin/dev-partners#16 (comment). In fact, we need to nothing until those new extensions are actually ratified(more details are needed in extenisons specification to approach). So I think maybe is a good idea that only implements the new extensions' names in toolchain Profiles support. |
README.mkd
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`-march = rv64imafdc_zicsr_ziccif_ziccrse_ziccamoa_zicclsm_za128rs_zba_zbb_zbc_zbs` | ||
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and `-march = rva20u64` is an illegal profile input, it not use uppercase letters. |
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"it not use" -> "it does not use"
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Updated, thanks for your checking.
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Isn't this incorrect due to the spaces around the '=' character?
-march = rv64imafdc_zicsr_ziccif_ziccrse_ziccamoa_zicclsm_za128rs_zba_zbb_zbc_zbs
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I think you are right, remove the incorrect spaces, thanks!
Update the syntax of description. Signed-off-by: Jiawei <jiawei@iscas.ac.cn>
To distinguish between ordinary extension input and input with profiles, | ||
profiles are assumed to be entered `at the beginning of the -march option`, and | ||
then input other extensions. Profiles `should use uppercase letters` in the `-march` | ||
option. |
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Incorrect placement of code (backtick) markup?
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I'm trying to emphasize here the rules for using, do you have any good solutions?
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To distinguish between ordinary extension input and input with profiles, | |
profiles are assumed to be entered `at the beginning of the -march option`, and | |
then input other extensions. Profiles `should use uppercase letters` in the `-march` | |
option. | |
To distinguish between ordinary extension input and input with profiles, | |
profiles are assumed to be entered `at the beginning of the -march option`, and | |
then input other extensions. Profiles *should use uppercase letters* in the `-march` | |
option. |
README.mkd
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e.g. `-march = RVA20U64` is a legal profile input, it will be expanded into: | ||
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`-march = rv64imafdc_zicsr_ziccif_ziccrse_ziccamoa_zicclsm_za128rs`, | ||
which include all the mandatory extensions required by this profile. | ||
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`-march = RVA20U64+zba_zbb_zbc_zbs` is also a legal profile input, it will add | ||
four new extensions after expanded profile strings: | ||
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`-march = rv64imafdc_zicsr_ziccif_ziccrse_ziccamoa_zicclsm_za128rs_zba_zbb_zbc_zbs` | ||
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and `-march = rva20u64` is an illegal profile input, it does not use uppercase letters. |
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Spaces around '=' character are incorrect?
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Removed, thank you!
Remove incorrect spaces using. Signed-off-by: Jiawei <jiawei@iscas.ac.cn>
The status of the profiles support was briefly discussed in today's SIG toolchain call:
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An initial patch was sent to the GCC mailing list today: https://gcc.gnu.org/pipermail/gcc-patches/2023-November/637490.html |
Uppercase strings being required in things like -march is very unusual; I would be much more in favour of keeping things lowercase |
The architecture review committee has sent out the following text about how profiles support in toolchains should look like:
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Draft LLVM implementation: llvm/llvm-project#76357. |
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string. We may need to pass it to backend so that we can emit an ELF attr proposed by riscv-non-isa/riscv-elf-psabi-doc#409.
Reverse ping. Is there any progress? |
The GCC implementation is tracked here: riscv-admin/dev-partners#16. There was a request to wait on the GCC patch regarding the adoption of profiles in toolchain components: https://gcc.gnu.org/pipermail/gcc-patches/2023-December/641025.html. So, at this point, we have clear guidelines from RVI regarding the adoption. We have this PR, and we have patches for GCC and LLVM. This can all move forward if upstream maintainers are fine with it. Given the relatively low impact on toolchains, I'm fine with waiting until the GCC 15 branch opens up. |
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string.
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string.
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string.
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string.
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string.
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string. This is recommitted as 66f88de was reverted because of failures caused by lacking `--target` option.
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string.
This PR implements the draft riscv-non-isa/riscv-toolchain-conventions#36. Currently, we replace specified profile in `-march` with standard arch string. This is recommitted as 66f88de was reverted because of failures caused by lacking `--target` option.
LLVM support landed upstream a few days ago (see also llvm/llvm-project#76357). |
The text in this PR currently differs from the ARC decision mentioned in #36 (comment) and the implementation in LLVM in llvm/llvm-project#76357 in two significant ways:
I worry that this inconsistency might cause compatibility issues. |
@pz9115 Hi Jiawei, can you please update the RFC according to the comment?
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This is a subset work form #26.
Add RISC-V Profiles format only. The doc record in:
https://docs.google.com/document/d/1TZXRIgVfQHWQ6xrZflHXUCSav6xNmliojrW2bEsvPno/edit.