pengfei added a comment. In D84225#3305140 <https://reviews.llvm.org/D84225#3305140>, @rnk wrote:
> In D84225#3304189 <https://reviews.llvm.org/D84225#3304189>, @pengfei wrote: > >> It's not a workaround. We do need to avoid the merging sometime. For >> example, given we have 2 branches begin with inline asm of `endbr`. We have >> to use `nomerge` to stop them been merged out of the branches. `sideeffect` >> doesn't help with that. > > That doesn't sound sufficient to ensure that `endbr` will be the first > instruction in that basic block, which I'm guessing is a requirement. PHI > nodes might cause register copies / spills to appear before `endbr`, and > instrumentation passes typically insert code at the top of basic blocks. It > sounds like we might need a more complete solution for tracking indirect > branch target blocks. Maybe `indirectbr` and basic block addresses already > feed into this, but I'm out of my depth here. > > Anyway, I don't want to make a value judgment here. I'm in favor of this > change. We should allow users to apply `nomerge` to inline asm, whether it is > a workaround or not. Thanks @rnk . Yes, so we emit `endbr` in a backend pass rather than this way. I just want to demonstrate why we can't merge inline asm sometime. I don't have a better example at a short time :) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D84225/new/ https://reviews.llvm.org/D84225 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
