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May 14, 2024
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[NFC] add explanation to register flags doc #91803

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fmayer May 10, 2024
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14 changes: 14 additions & 0 deletions llvm/docs/MIRLangRef.rst
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Expand Up @@ -540,41 +540,55 @@ Register Flags
The table below shows all of the possible register flags along with the
corresponding internal ``llvm::RegState`` representation:

..
Keep this in sync with MachineInstrBuilder.h
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Does this appear in the generated output?

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No: https://github.com/llvm/llvm-project/blob/6dab9ff72a1410989553285490f2a077c707c855/llvm/docs/MIRLangRef.rst


.. list-table::
:header-rows: 1

* - Flag
- Internal Value
- Meaning

* - ``implicit``
- ``RegState::Implicit``
- Not emitted register (e.g. carry, or temporary result).

* - ``implicit-def``
- ``RegState::ImplicitDefine``
- ``implicit`` and ``def``

* - ``def``
- ``RegState::Define``
- Register definition.

* - ``dead``
- ``RegState::Dead``
- Unused definition.

* - ``killed``
- ``RegState::Kill``
- The last use of a register.

* - ``undef``
- ``RegState::Undef``
- Value of the register doesn't matter.

* - ``internal``
- ``RegState::InternalRead``
- Register reads a value that is defined inside the same instruction or bundle.

* - ``early-clobber``
- ``RegState::EarlyClobber``
- Register definition happens before uses.
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This one probably needs more elaboration


* - ``debug-use``
- ``RegState::Debug``
- Register 'use' is for debugging purpose.

* - ``renamable``
- ``RegState::Renamable``
- Register that may be renamed.
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Also probably needs more explanation


.. _subregister-indices:

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