[LLHD] Remove drive-only signals in Sig2Reg pass #8629
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| })) { | ||
| LLVM_DEBUG(llvm::dbgs() << " - Removing drive-only signal " | ||
| << sigOp.getName() << "\n"); | ||
| for (auto *user : sigOp->getUsers()) |
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I think early increment is necessary
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Nice catch, thanks! 👍
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LGTM!
Could you add this as canonicalization as well in a follow-up?
This pass currently assumes that you don't care about tracking signals by their name afterward (e.g., in simulation). I don't think we want this by default in canonicalization. We might even want to add an option to this pass to insert hw.wire or similar operations to the promoted SSA values to keep the name references in the future.
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@uenoku @maerhart Do you remember what our stance was on canonicalizer complexity? Replacing signals with the driven value would be nice to have as a canonicalization, but I remember discussing that walking all users of an op in a canonicalizer might be too costly -- is that a "policy" we settled on? |
Extend the Sig2Reg LLHD pass to completely remove a signal and all its associated drives if the signal is only driven, but never probe or used in any other way.
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Extend the Sig2Reg LLHD pass to completely remove a signal and all its associated drives if the signal is only driven, but never probe or used in any other way.
Extend the Sig2Reg LLHD pass to completely remove a signal and all its associated drives if the signal is only driven, but never probe or used in any other way.