[PATCH] D132386: [AArch64][PAC] Lower auth/resign into checked sequence.

[Peter Smith via Phabricator via llvm-commits]

peter.smith added inline comments.


================
Comment at: llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp:1227
+
+  // We can expand AUT/AUTPAC into 3 possible sequences:
+  // - unchecked:
----------------
apazos wrote:
> Should the PAuth ABI for ELF documentation in 
> https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst 
> have a note on x16/x17 being used for lowering auth/resign sequences?
Not had a chance to reason through all of this in detail. My instinct is that this is already covered in the PCS (see below) if there are additional restrictions that are needed in the PAuthABI then it will be worth raising a github issue (or a pull request).

The x16/x17 registers are mentioned in the procedure call standard as corruptible by intra-procedure calls so compilers already have to assume that they may be corrupted on a function call https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#611general-purpose-registers 


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https://reviews.llvm.org/D132386