[PATCH] D116465: [SPIRV 6/6] Add 2 essential passes and the simplest tests

[Renato Golin via Phabricator via llvm-commits]

rengolin added a comment.

I didn't mean the duplicated types/constants would survive into codegen, but I get your meaning, it would have to be commoned up at some point.

So, what about a singleton emitter for types and constants?

Instead of just `get_next_id()` you could have a `get_type(...)` and `get_constant(...)` that returns a cached MIR node if it has created a similar one already, or creates a new one, caches and returns it.

In this way, there's only ever one copy of each and they're only generated once, with no need to deduplicate.

The only issue with this implementation is that types, constants, functions, instructions will all have intertwined IDs, but never refer to larger IDs, by design.

When emitting "int foo()", if `int` hadn't been emitted before, it'd get the next id (say, %23) and then `foo` would get %24 and would refer to %23 as its type.

Eventually, all types used in the program would have been emitted already and be brought up from the cache every time.

This way, there's no need to renumber or common up and the space is still optimal.

What am I missing?


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