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Hi, I've spent some time playing around with GlobalISel on the AMDGPU target, and I was wondering if there is any reason to have RegisterBankInfo::getInstrAlternativeMappings() and RegisterBankInfo::getInstrMapping() as separate functions. Could we instead replace these two functions with just one: RegisterBankInfo::getInstrMappings() and then just treat the first mapping in the list as the 'default' mapping to use for 'Fast' RegBankSelect mode? T...

...registers and creates the new vregs and rewrites as necessary. Is this the way this is intended to work? This sort of makes sense, since it is legal in the sense that applyMapping can deal with it. The cases that need to be rewritten can then have a very high, but not impossible cost in the case of getInstrAlternativeMappings. Lying about the actually legal banks seems counterintuitive to me. Should there be something like a new RepairingPlacement type for this to just create the vregs without inserting the copy? -Matt -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists...

...rectly being rewritten, but I haven’t finished handling every case to run into them yet. > >> This sort of makes sense, since it is legal in the sense that applyMapping can deal with it. The cases that need to be rewritten can then have a very high, but not impossible cost in the case of getInstrAlternativeMappings. >> >> Lying about the actually legal banks seems counterintuitive to me. > > Agree, that’s not the way it’s supposed to work. > >> Should there be something like a new RepairingPlacement type for this to just create the vregs without inserting the copy? > &g...