Special-case unreachable If conditions in IRBuilder #7095
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When IRBuilder completes a scope that contains an unreachable expression, it has to find the last unreachable expression and drop any concretely typed expression that precedes it. If the original unreachable expression has been made a child of some other expression, that's usually fine because that other expression will become unreachable as well. However, if conditions are special because they can be unreachable without making their ifs unreachable, so we have to work harder to find unreachable if conditions.
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This is a simpler but arguably hackier alternative to #7094. |
kripken
reviewed
Nov 20, 2024
| sawUnreachable = true; | ||
| break; | ||
| } | ||
| } |
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Would it be simpler to change this?
Line 230 in e13bf0f
I think we could just make an if with an unreachable condition be unreachable, unless I'm missing a reason not to.
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(that would avoid special-casing here, and seems simpler overall: the code is dead, so let's mark it dead)
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I'm on board with this and this is what #7094 does, but it's not as simple as we would like. I'm still chasing down fuzz bugs on that PR.
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Closing this in favor of #7094. |
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When IRBuilder completes a scope that contains an unreachable
expression, it has to find the last unreachable expression and drop any
concretely typed expression that precedes it. If the original
unreachable expression has been made a child of some other expression,
that's usually fine because that other expression will become
unreachable as well. However, if conditions are special because they can
be unreachable without making their ifs unreachable, so we have to work
harder to find unreachable if conditions.