[PATCH] D158062: [RISCV] Teach RISCVMergeBaseOffset to handle inline asm

Thu Aug 31 13:53:58 PDT 2023

jrtc27 added a comment.

In D158062#4632464 <https://reviews.llvm.org/D158062#4632464>, @craig.topper wrote:

> In D158062#4632461 <https://reviews.llvm.org/D158062#4632461>, @nickdesaulniers wrote:
>
>> @samitolvanen is reporting that this is causing breakage for us in the Linux kernel: https://github.com/ClangBuiltLinux/linux/issues/1928.
>>
>> Please consider whether this can be fixed forward quickly, or should be reverted. Otherwise I will revert shortly.
>
> I think the problem is that atomic instructions don't have an immediate offset field so they are different than other instructions. I'm not sure we can generically do this patch for the "m" constraint. We should revert.

Doing it for m is fine. What's not fine is doing it for A, as used by Linux in the reported errors, which presumably presents itself close enough to m to not be caught by the code here. Presumably we need a constraint_A_with_global_1 test to catch this.

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https://reviews.llvm.org/D158062