[PATCH] D67185: [RISCV] Add support for -ffixed-xX flags

[Simon Cook via Phabricator via cfe-commits]

simoncook added a comment.

For added context, I have gone and double-checked with GCC's implementation both for AArch64 and RISC-V and for registers used by the calling convention the compiler will still use them for argument passing and return values, but otherwise won't use it for any temporaries/register allocation purposes, which does have the side effect of confusing behaviour unless carefully documented.

I can implement errors for using calling convention registers when there are functions that take arguments, but this would be an explicit deviation in behaviour between the two compilers. I presume we would want to do that anyway because it's safer/more clear?


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https://reviews.llvm.org/D67185