[RISCV] Support .option (no)autocompress #122483
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This is the implementation of a new assembler-only option to allow the automatic compression of RISC-V instructions to be switched off without changing the currently enabled architectural features. This allows users better control over the autocompression feature of the assembler, so they can get the exact instructions they want. This will become more useful as the following things happen: - `.option norvc` is deprecated/removed (which is sometimes used for this purpose). - Extensions are added where the destination instruction cannot be disabled separately to the source instruction, either because the destination is in the base architecture, or because it is in the same extension as the source. - Extensions wider than 32-bits are added, which make CompressPats more complex to use intuitively, especially if the destination is a 32-bit instruction.
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The assembly manual proposal is here: riscv-non-isa/riscv-asm-manual#122 |
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Thanks for doing this. Kito and I have talked about something similar in the past. .option rvc has been broken since Zca/Zcf/Zcd was introduced. |
Yeah. Just like EF_RVC conflates two things (C extension being present and IALIGN=16), |
MaskRay
reviewed
Jan 11, 2025
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| # RUN: llvm-mc -triple riscv32 -show-encoding -mattr=+c < %s \ | |||
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This is the implementation of a new assembler-only option to allow the automatic compression of RISC-V instructions to be switched off without changing the currently enabled architectural features.
This allows users better control over the autocompression feature of the assembler, so they can get the exact instructions they want.
This will become more useful as the following things happen:
.option norvcis deprecated/removed (which is sometimes used for this purpose).