[PATCH] D64101: [LoopUnroll] fix cloning callbr

Wed Jul 3 15:54:25 PDT 2019

fhahn added a comment.

Maybe we could make the semantics of `callbr` a bit more explicit in LangRef?

Currently it only mentions that the only use is to implement asm goto's like in GCC. IIUC, asm goto cannot have outputs and the inputs are explicit, those can be updated while unrolling. According to https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html 6.47.2.7 Goto Labels, if the assembly in the asm goto modifies anything, it needs a "memory" clobber. I think this should be handled like regular inline assembly already in LLVM?

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D64101/new/

https://reviews.llvm.org/D64101