When a block has only a single, unconditional predecessor, we should merge it into its predecessor. We see this relatively frequently due to the way that cranelift-wasm creates blocks (which can certainly be improved, but I think can't fully solve this issue).
One option is to do this during CLIF construction in cranelift-frontend when we call seal_block, as that is when we are declaring that all predecessors for a block have been linked up.
Another option is to do this somewhere in the mid-end, either when building the e-graph or when elaborating out of it.
We might want to do both, since legalization can also introduce new blocks.
When a block has only a single, unconditional predecessor, we should merge it into its predecessor. We see this relatively frequently due to the way that
cranelift-wasmcreates blocks (which can certainly be improved, but I think can't fully solve this issue).One option is to do this during CLIF construction in
cranelift-frontendwhen we callseal_block, as that is when we are declaring that all predecessors for a block have been linked up.Another option is to do this somewhere in the mid-end, either when building the e-graph or when elaborating out of it.
We might want to do both, since legalization can also introduce new blocks.